| 1. |
- Bakas, Panagiotis, et al.
(författare)
-
Hybrid alternate-common-arm converter with high power capability : Potential and limitations
- 2020
-
Ingår i: IEEE transactions on power electronics. - : IEEE. - 0885-8993 .- 1941-0107. ; 35:12, s. 12909-12928
-
Tidskriftsartikel (refereegranskat)abstract
- This paper studies a new hybrid converter thatutilizes thyristors and full-bridge (FB) arms for achieving higherpower capability than the full-bridge (FB) modular multilevel converter (MMC) with reduced semiconductor requirements. The study covers the theoretical analysis of the energy balancing,the dimensioning principles, the maximum power capability, and the limitations imposed by the discontinuous operation of theconverter. Based on the analysis of these aspects, the theoretical analysis is concluded by identifying the design constraints that need to be fulfilled for achieving the maximum power capabilityof the converter. It is concluded that the maximum power capability can be achieved for a certain range of modulation indices and is limited by both the commutation time of the thyristors andthe power angle. Finally, simulation and experimental results that confirm the theoretical analysis and the feasibility of the studied converter are presented and discussed.
|
|
| 2. |
- Ciftci, Baris, et al.
(författare)
-
Wireless control of modular multilevel converter autonomous submodules : 23rd European Conference on Power Electronics and Applications
- 2021
-
Ingår i: Proceedings 23rd European Conference on Power Electronics and Applications. - : Institute of Electrical and Electronics Engineers (IEEE).
-
Konferensbidrag (refereegranskat)abstract
- The wireless control of modular multilevel converter (MMC) submodules might offer advantages for MMCs with a high number of submodules. However, the control system should tolerate the stochastic nature of the wireless communication, continue the operation flawlessly or, at least, avoid overcurrents, overvoltages, and component failures. The previously proposed control methods enabled to control the submodules wirelessly with consecutive communication errors up to hundreds of control cycles. The submodule control method in this paper facilitates the MMC to safely overcome communication errors that last longer and when the MMC experiences significant electrical disturbances during the errors. The submodules are proposed to operate autonomously by implementing a replica of the central controller in the submodules and drive the replicas based on the local variables and the previously received data. The simulation and experimental results verify the proposed control method.
|
|
| 3. |
- Ciftci, Baris, 1987-
(författare)
-
Wireless Control of Modular Multilevel Converter Submodules
- 2022
-
Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The modular multilevel converter (MMC) has extensively been used in high-voltage, high-power applications such as high-voltage dc transmission systems and flexible alternating current transmission systems. The control of MMC submodules is conventionally realized using wired communication systems. However, MMCs in high-power applications consist of up to thousands of submodules. Significant issues arise with the wired communication systems in the MMC valve halls of these applications, including considerable workforce and time requirements for the cable deployment.The main objective of this thesis is to propose a wireless control method for MMC submodules. Wireless communication has fundamental differences from wired communication regarding latency and reliability. Since the control of submodules is a time-critical process, the MMC internal control and modulation methods used with wired communication systems are not directly applicable to wireless communication systems.A wireless control method is proposed for the MMC submodules. The proposal is based on the distributed control of MMCs, where the control and modulation tasks are shared between a central controller and the submodule controllers. The fundamental data to transmit wirelessly is the insertion indices for each of the MMC arms and the synchronization signal for the modulation carriers generated in the submodules. The amount and the cycle time of the time-critical wireless data are in the range of tens of bytes and hundreds of microseconds and are independent of the total number of submodules. The proposal is experimentally verified on a laboratory-scale MMC.The original proposal is enhanced against the communication errors such that the submodules suffering from the errors can continue their modulation smoothly and uninterruptedly. If continuing the modulation is not feasible in case of very long-lasting communication errors, the submodules switch to a safe operation mode to avoid faults in the MMC. Moreover, wireless control of submodules with ac-side faults is analyzed. The MMC rides through the ac-side faults even with a complete loss of communication before or after the fault instant.A wireless communication network based on 5G New Radio is designed theoretically for an example full-scale MMC valve hall according to the proposed wireless control method. It is evaluated that the latency and reliability of the proposed communication solution can correspond to the proposed wireless control method requirements. Finally, the electromagnetic interference from the MMC submodules is measured as below 500 MHz, which does not affect a wireless communication held in the multi-GHz range.
|
|
| 4. |
- Ciftci, Baris, et al.
(författare)
-
Wireless control of modular multilevel converter submodules under ac-side faults
- 2021
-
Konferensbidrag (refereegranskat)abstract
- Wireless control of modular multilevel converter (MMC) submodules has been offered recently with potentially lower cost and higher availability advantages for the converter station. In this paper, the wireless control of MMC submodules under ac-side faults is investigated. The central controller of the MMC is equipped for the unbalanced grid conditions. Local current controllers in the submodules are operated autonomously in case of loss of wireless communication during the fault. A set of simulations with single line-to-ground, line-to-line, and three-phase-to-ground faults reveal that the MMC rides through the faults in all the cases with the expected communication conditions or when the communication is lost before or after the fault instant.
|
|
| 5. |
- Ciftci, Baris, et al.
(författare)
-
Wireless Control of Modular Multilevel Converter Submodules With Communication Errors
- 2022
-
Ingår i: IEEE Transactions on Industrial Electronics. - : Institute of Electrical and Electronics Engineers (IEEE). - 0278-0046 .- 1557-9948. ; 69:11, s. 11644-11653
-
Tidskriftsartikel (refereegranskat)abstract
- Wireless control of modular multilevel converter (MMC) submodules can benefit from different points of view, such as lower converter cost and shorter installation time. In return for the advantages, the stochastic performance of wireless communication networks necessitates an advanced converter control system immune to the losses and delays of the wirelessly transmitted data. This paper proposes an advancement to the distributed control of MMCs to utilize in wireless submodule control. Using the proposed method, the operation of the MMC continues smoothly and uninterruptedly during wireless communication errors. The previously proposed submodule wireless control concept relies on implementing the modulation and individual submodule-capacitor-voltage control in the submodules using the insertion indices transmitted from a central controller. This paper takes the concept as a basis and introduces to synthesize the indices autonomously in the submodules during the communication errors. This new approach allows the MMC continue its operation when one, some, or all submodules suffer from communication errors for a limited time. The proposal is validated experimentally on a laboratory-scale MMC.
|
|
| 6. |
- Arévalo-Soler, Josep, et al.
(författare)
-
Dynamic Converter Control Role Configuration in Grid of Grids
- 2023
-
Ingår i: 2023 25th European Conference on Power Electronics and Applications, EPE 2023 ECCE Europe. - : Institute of Electrical and Electronics Engineers (IEEE).
-
Konferensbidrag (refereegranskat)abstract
- The control role of power converters conforming an HVDC link is generally static, i.e. changing the control role of the power converters is not considered in the power system operation. In this paper a lab-scaled demonstration on the control role reconfiguration while an AC/DC/AC link is in operation is presented.
|
|
| 7. |
- Bessegato, Luca, 1989-, et al.
(författare)
-
Control and Admittance Modeling of an AC/AC Modular Multilevel Converter for Railway Supplies
- 2020
-
Ingår i: IEEE transactions on power electronics. - : IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC. - 0885-8993 .- 1941-0107. ; 35:3, s. 2411-2423
-
Tidskriftsartikel (refereegranskat)abstract
- Modular multilevel converters (MMCs) can be configured to perform ac/ac conversion, which makes them suitable as railway power supplies. In this paper, a hierarchical control scheme for ac/ac MMCs for railway power supplies is devised and evaluated, considering the requirements and the operating conditions specific to this application. Furthermore, admittance models of the ac/ac MMC are developed, showing how the suggested hierarchical control scheme affects the three-phase and the single-phase side admittances of the converter. These models allow for analyzing the stability of the interconnected system using the impedance-based stability criterion and the passivity-based stability assessment. Finally, the findings presented in this paper are validated experimentally, using a down-scaled MMC.
|
|
| 8. |
- Blinov, Andrei, et al.
(författare)
-
High Gain DC-AC High-Frequency Link Inverter With Improved Quasi-Resonant Modulation
- 2022
-
Ingår i: IEEE Transactions on Industrial Electronics. - : Institute of Electrical and Electronics Engineers (IEEE). - 0278-0046 .- 1557-9948. ; 69:2, s. 1465-1476
-
Tidskriftsartikel (refereegranskat)abstract
- This article presents a high gain pure sine- wave inverter based on the full-bridge dc-ac high-frequency link cycloconverter topology for telecom or general-purpose applications. The improved quasi-resonant modulation method allows reduction of ringing and turn-off losses of the dc-side switches. This is achieved with minimal energy circulation and requires no multi-mode operation or extra auxiliary clamping circuits. The soft switching can be provided even if relatively large lossless snubber capacitors are connected across the input side transistors. Moreover, two of the switches at the ac side operate at fundamental frequency, while the rest feature zero current turn-off. A 48 V-DC to 230 V-AC, 1.2 kW sine-wave inverter prototype was developed to verify the proposed concept.
|
|
| 9. |
- Chaffey, Geraint, et al.
(författare)
-
Design of backup protection for the DC interconnection of adjacent point-to-point HVDC systems
- 2022
-
Ingår i: Proceedings 16th International Conference on Developments in Power System Protection, DPSP 2022. - : Institution of Engineering and Technology (IET). ; , s. 25-30
-
Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- In order to provide additional flexibility in future power systems, it could be beneficial to connect existing point-to-point highvoltage direct-current (HVDC) systems at the DC-side into a multiterminal network. Such a network would allow increased operational flexibility, continued operation in case of maintenance, and could reduce the end-to-end losses in the overall system. The protection of such a system, however, poses interesting challenges with constraints which differ slightly from typical HVDC grid protection studies. This paper focuses on the trade-offs surrounding the backup protection strategy following failure of a DC circuit breaker in the primary protection role. For this particular application, where a control retrofit should be avoided, the focus is on enabling quicker recovery rather than attempting to maintain continuous operation on a charged and healthy network. Therefore, the functional requirements on the backup switchgear are in some respects reduced compared to that required for primary protection. The benefits of reduced voltage switchgear for this backup protection application are therefore investigated.
|
|
| 10. |
- Ciftci, Baris, 1987-, et al.
(författare)
-
Wireless Communication in Modular Multilevel Converters and Electromagnetic Interference Characterization
- 2022
-
Ingår i: IEEE Access. - : Institute of Electrical and Electronics Engineers (IEEE). - 2169-3536. ; , s. 38189-38201
-
Tidskriftsartikel (refereegranskat)abstract
- The wireless control of modular multilevel converter (MMC) submodules was recently proposed. The success of the control depends on specialized control methods suitable for wireless communication and a properly designed wireless communication network in the MMC valve hall while aiming for low latency and high reliability. The wireless communication in the hall can be affected by the electromagnetic interference (EMI) of MMC submodules, voltage and current transients. In this article, firstly, a wireless communication network based on 5G New Radio is designed for an example full-scale MMC valve hall. After that, the radiated EMI characteristics of the MMC submodules with different voltage and current ratings and two dc circuit breakers are measured. The effects of EMI on wireless communication in the multi-GHz frequency band are tested. The interference from the components is confined below 500 MHz, and the wireless communication with 5825 MHz center frequency is not affected by the interference.
|
|
| 11. |
- Ciftci, Baris, et al.
(författare)
-
Wireless Control of Modular Multilevel Converter Submodules
- 2021
-
Ingår i: IEEE transactions on power electronics. - : Institute of Electrical and Electronics Engineers (IEEE). - 0885-8993 .- 1941-0107. ; 36:7, s. 8439-8453
-
Tidskriftsartikel (refereegranskat)abstract
- Wireless control of modular multilevel converter (MMC) submodules offers several potential benefits to exploit, such as decreased converter costs and ease in converter installation. However, wireless control comes with several challenging engineering requirements. The control methods used with wired communication networks are not directly applicable to the wireless control due to the latency and reliability differences of wired and wireless networks. This article reviews the existing control architectures of MMCs and proposes a control and communication method for wireless submodule control. Also, a synchronization method for pulsewidth modulation carriers is proposed suitable for wireless control. The imperfections of wireless communication, such as higher latency and packet losses compared to wired communication, are analyzed for the operation of MMCs. The latency is fixed with a proper controller and wireless network design. The converter is rendered immune to the packet losses by decreasing the closed-loop control bandwidth. The functionality of the proposal is verified, for the first time, experimentally on a laboratory-scale MMC using a simple wireless network. It is shown that wireless control of MMC submodules with the proposed approach can perform comparably to the wired control.
|
|
| 12. |
- Heinig, Stefanie, et al.
(författare)
-
Auxiliary Power Supplies for High-Power Converter Submodules : State of the Art and Future Prospects
- 2022
-
Ingår i: IEEE transactions on power electronics. - : Institute of Electrical and Electronics Engineers (IEEE). - 0885-8993 .- 1941-0107. ; 37:6, s. 6807-6820
-
Tidskriftsartikel (refereegranskat)abstract
- Recent developments in medium-voltage (MV) silicon and silicon carbide (SiC) power semiconductor devices are challenging state-of-the-art converter and auxiliary power supply (APS) designs. The APS is an important converter component, which energizes the gate-drive units and, therefore, has an influence on the overall reliability and efficiency of the converter system. There has, however, been comparably little research on how the APS of high-power converter submodules can be realized, in particular, for high-voltage applications. New, or improved, solutions may build on state-of-the-art topologies in the near future, but utilize MV SiC technology in the APS circuit itself to enable improved efficiency, reliability, simplicity, and compactness. Externally-fed APS concepts could provide several further advantages. Their various benefits on converter and system level may enable them to be a competitive solution for future APS concepts. Especially, light-based power supply systems are considered most useful since they offer extreme voltage isolation capability and immunity to electromagnetic interference. This article presents a review of the wide range of solutions for APSs, possible implementation options, and the most important design considerations. The different solutions are evaluated in a qualitative fashion, providing an overview of available APS concepts with regard to the requirements for high-power converter applications.
|
|
| 13. |
- Heinig, Stefanie, et al.
(författare)
-
Auxiliary Power Supplies for High-Power Converter Submodules: State-of-the-Art and Future Prospects
- 2020
-
Annan publikation (övrigt vetenskapligt/konstnärligt)abstract
- Recent developments in high-voltage (HV) silicon and silicon carbide (SiC) power semiconductor devices are challenging state-of-the-art converter and auxiliary power supply (APS) designs. There has been comparably little research on how the APS of converter submodules can be realized. The APS is, however, an important converter component, which energizes the gate-drive units and, therefore, has an influence on the overall reliability and efficiency of the converter system. The wide range of possible solutions for APSs motivates an overview of state-ofthe- art and alternative concepts. Such a review is presented in this article, along with a qualitative evaluation regarding APS requirements for high-power converter applications.Moreover, future prospects of internal and external APS designs are discussed. Internal solutions may build on state-of-the-art topologies in the near future, but utilize HV SiC technology in the APS circuit itself to enable improved efficiency, reliability, simplicity, and compactness. The active voltage-divider-based APS is a promising concept if the required power is relatively low. Series-connected bootstrap circuits or snubber-based power tapping could provide a reduction of complexity and cost.It is recognized that several advantages are achievable by employing external APS concepts. Light-based power supply systems, comparably expensive today but under rapid development and with optimistic cost predictions, are considered most useful in this respect. Their extreme voltage isolation capability and immunity to electromagnetic interference, combined with various benefits on converter and system level, enable them to be a competitive solution for future APS concepts
|
|
| 14. |
- Heinig, Stefanie
(författare)
-
Main Circuits, Submodules, and Auxiliary Power Concepts for Converters in HVDC Grids
- 2020
-
Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- In order to enable the massive introduction of renewable energies the need for high-voltage direct current (HVDC) grids is anticipated. Large, globally interconnected HVDC networks will likely be the most cost-efficient means to balance electricity demand and available generation. In a meshed system it is important to ensure reliability, robustness, failure management, and fast protection of equipment. In case of a failure somewhere in the grid, the remaining system must be kept operational. State-of-the-art converter implementations are either not adapted to future system requirements or lead to increased losses, cost, and converter footprint. Therefore, this thesis examines several aspects of how to improve the HVDC converter design and functionality with the ultimate aim of developing reliable, highly efficient, cost-effective, more compact and lightweight converters.Advancements are made on several levels of the converter hardware hierarchy. Main circuits, submodule (SM) topologies, and auxiliary power supply (APS) concepts are investigated and new solutions are proposed. On main-circuit level, different voltage-source converters (VSCs) are evaluated in terms of their energy storage elements. This is useful to compare the physical volume of capacitors required by each topology and, thus, to address the need to develop more compact converter stations. The theoretical analysis indicates that the required energy storage of the alternate arm converter (AAC) is smaller compared to the modular multilevel converter (MMC).On SM level, new topologies are evaluated with the goal to find topologies, which enable efficient handling of dc-side short circuits, reduction of power loss, and lower SM capacitance. The semi-full-bridge (SFB) SM is identified as one of the most promising topologies from this point of view and is investigated in detail. A control concept for capacitor balancing and several options for improved operation of the SFB are presented. Furthermore, a novel SM cluster topology is proposed which features low conduction losses and increased protection against explosion.The availability of a reliable APS system is crucial for equipment in future HVDC grids. Therefore, APS solutions are investigated considering design complexity, reliable performance, and power consumption. This thesis presents a novel combined optical power and data transmission concept which is tailored to the specific requirements of HVDC converters employing high-voltage (HV) silicon carbide (SiC) devices. The proposed concept offers a robust solution for isolated APS and signal transmission across any voltage barrier.
|
|
| 15. |
- Heinig, Stefanie, et al.
(författare)
-
Single-Fiber Combined Optical Power and Data Transmission for High-Voltage Applications
- 2020
-
Ingår i: Proceedings of the 46th Annual Conference of the IEEE Industrial Electronics Society, IECON 2020. - : Institute of Electrical and Electronics Engineers (IEEE).
-
Konferensbidrag (refereegranskat)abstract
- In this paper, power-over-fiber technology is used for combined power and data transfer applying amplitude-modulated light representing a pulse-width modulated signal that could be used for control of, for instance, power semiconductor devices in high-power converters. Even though the concept is generally applicable, an experimental verification aiming for a gate-driver of a switch in a modular multilevel converter is presented. In order to achieve a good resilience against electromagnetic noise, a concept where the modulated light is demodulated as a comparably powerful current signal is employed. A 5 MHz boost converter steps up the voltage to 15-20 V, such that silicon or silicon-carbide based power devices could be controlled. From the results, it can be concluded that it is possible to achieve transmission of a control signal with a latency of less than 500 ns for a gate drive unit of a high-power converter. The concept can easily be scaled up to powers of several watt.
|
|
| 16. |
- Huang, Tianqi, et al.
(författare)
-
Failure Characterization of Discrete SiC MOSFETs under Forward Power Cycling Test
- 2024
-
Ingår i: Energies. - : MDPI AG. - 1996-1073. ; 17:11
-
Tidskriftsartikel (refereegranskat)abstract
- Silicon carbide (SiC)-based metal-oxide-semiconductor field-effect transistors (MOSFETs) hold promising application prospects in future high-capacity high-power converters due to their excellent electrothermal characteristics. However, as nascent power electronic devices, their long-term operational reliability lacks sufficient field data. The power cycling test is an important experimental method to assess packaging-related reliability. In order to obtain data closest to actual working conditions, forward power cycling is utilized to carry out SiC MOSFET degradation experiments. Due to the wide bandgap characteristics of SiC MOSFETs, the short-term drift of the threshold voltage is much more serious than that of silicon (Si)-based devices. Therefore, an offline threshold voltage measurement circuit is implemented during power cycling tests to minimize errors arising from this short-term drift. Different characterizations are performed based on power cycling tests, focused on measuring the on-state resistance, thermal impedance, and threshold voltage of the devices. The findings reveal that the primary failure mode under forward power cycling tests, with a maximum junction temperature of 130 degrees C, is bond-wire degradation. Conversely, the solder layer and gate oxide exhibit minimal degradation tendencies under these conditions.
|
|
| 17. |
- Jacobs, Keijo, et al.
(författare)
-
Comparative Evaluation of Voltage Source Converters With Silicon Carbide Semiconductor Devices for High-Voltage Direct Current Transmission
- 2021
-
Ingår i: IEEE transactions on power electronics. - : Institute of Electrical and Electronics Engineers (IEEE). - 0885-8993 .- 1941-0107. ; 36:8, s. 8887-8906
-
Tidskriftsartikel (refereegranskat)abstract
- Recent advancements in silicon carbide (SiC) power semiconductor technology enable developments in the high-power sector, e.g., high-voltage-direct-current (HVdc) converters for transmission, where today silicon (Si) devices are state-of-the-art. New submodule (SM) topologies for modular multilevel converters offer benefits in combination with these new SiC semiconductors. This article reviews developments in both fields, SiC power semiconductor devices and SM topologies, and evaluates their combined performance in relation to core requirements for HVdc converters: grid code compliance, reliability, and cost. A detailed comparison of SM topologies regarding their structural properties, design and control complexity, voltage capability, losses, and fault handling is given. Alternatives to state-of-the-art SMs with Si insulated-gate bipolar transistors (IGBTs) are proposed, and several promising design approaches are discussed. Most advantages can be gained from three technology features. First, SM bipolar capability enables dc fault handling and reduced the energy storage requirements. Second, SM topologies with parallel conduction paths in combination with SiC metal-oxide-semiconductor field-effect transistors offer reduced losses. Third, a higher SM voltage enabled by a higher blocking voltage of SiC devices results in a reduced converter complexity. For the latter, ultrahigh-voltage bipolar devices, such as SiC IGBTs and SiC gate turn-off thyristors, are envisioned.
|
|
| 18. |
- Jacobs, Keijo, 1988-
(författare)
-
Silicon-Carbide-Based High-Voltage Submodules for HVDC Voltage-Source Converters
- 2020
-
Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- In order to transition to renewable energy sources and simultaneously meet the increasing demand for electrical energy, highly flexible and efficient grids are required. High-voltage direct-current (HVDC) transmission and grids are foreseen to be a vital part of the future electricity grid. Voltage source converters (VSCs), interfacing between HVDC and high-voltage alternating current (HVAC) technology, need to comply with grid code, and offer high reliability and cost efficiency. The state-of-the-art VSC topology is the modular multilevel converter (MMC), which offers tailored harmonic performance, modularity, fault handling, redundancy, and low losses.This thesis investigates improvements for VSCs enabled by novel silicon carbide (SiC) power semiconductor devices. These devices feature lower losses, higher blocking voltage, and higher maximum operation temperature. However, a co-design of the different hardware levels (i.e., converter, submodule (SM), power device, and semiconductor) is required to unleash their full potential. The thesis features contributions on several of these hardware levels, aiming at improvements regarding defined technical requirements for VSCs.It has been shown that, on converter level, future ultrahigh-voltage (UHV) SiC bipolar devices with blocking voltages of up to 50 kV have the potential for significant reduction of converter complexity, volume, and losses. The increased SM voltage is a challenge for internal fault handling, which can be met by a proposed novel SM feature, the discharge loop.On SM level, additional improvements are enabled by synergies between power semiconductor device technology and SM topology. A comparative evaluation of a large variety of SM topologies in combination with different SiC power semiconductor device technologies identifies several promising design approaches for future SMs. An alternative to the state-of-the-art half-bridge and full-bridge SM is the semi-full-bridge, which is investigated intensively. It features lower switch count and lower losses compared to the full-bridge, while offering DC fault handling capability. Another topology, the double-connected double-zero SM, features additional conduction loss reduction in combination with SiC metal-oxide-semiconductor field-effect transistors (MOSFETs), which is enabled by parallel current paths during certain switching states. A SM cluster enhancing this effect is proposed.Finally, results on the optimization of SiC PiN diodes via different charge carrier lifetime tailoring methods are presented. The target application is a high-voltage high-frequency LCC converter. In the future, such diodes will also be required as anti-parallel diodes for novel UHV bipolar SiC devices, as bootstrap diodes in gate drivers, and as a part of snubber circuits.
|
|
| 19. |
- Jahn, Ilka, et al.
(författare)
-
A holistic method for optimal design of HVDC grid protection
- 2021
-
Ingår i: Electric power systems research. - : Elsevier BV. - 0378-7796 .- 1873-2046. ; 196
-
Tidskriftsartikel (refereegranskat)abstract
- Protection system design for high-voltage direct-current (HVDC) grids using DC circuit breakers (DCCBs) is not straightforward. Both hardware parameters, such as line inductors and DCCBs, as well as software parameters, such as protection threshold settings and protection margins, have to be taken into account and interact. Previous studies focused on the impact of specific parameters (e.g., line inductors) while other parameters (e.g., maximum DCCB currents) were checked manually for compliance with constraints. This paper presents a new holistic method for HVDC grid protection design. The approach is no longer exclusively based on parameter sweeps but solves HVDC grid protection as a classic optimization problem with an optimization goal and constraints. Electromagnetic transient (EMT) simulations are embedded into the optimization tool such that the system dynamic response is taken into account. Results for two example test cases and two example optimization goals are provided. For instance, the method can achieve a reduced sum of line inductors compared to an initial guess. The proposed method is useful to find a more optimally designed HVDC protection system, and practical because it makes sure that the constraints (e.g., maximum DCCB current, no converter blocking and large protection margins) are fulfilled.
|
|
| 20. |
- Jahn, Ilka, et al.
(författare)
-
A MISO Fault Detection for HVDC Grids
- 2021
-
Konferensbidrag (refereegranskat)abstract
- Research on fault detection for high-voltage direct current (HVDC) grids has had a focus on single-ended DC fault detection using information from only the local line end. This paper proposes the use of additional information from neighbouring lines around the same busbar in a multiple-input single-output (MISO) fault detection. Simulations results show that the protection’s dependability and security margins are increased which is particularly useful for remote faults in long lines with small line inductors. A discussion on practical implementation taking into account possible intellectual property (IP) aspects is added. A MISO fault detection can be useful to overcome some of the uncertainties due to missing knowledge about implementation details.
|
|
| 21. |
- Jahn, Ilka, et al.
(författare)
-
An Architecture for a Multi-Vendor VSC-HVDC Station With Partially Open Control and Protection
- 2022
-
Ingår i: IEEE Access. - : Institute of Electrical and Electronics Engineers (IEEE). - 2169-3536. ; 10, s. 13555-13569
-
Tidskriftsartikel (refereegranskat)abstract
- High voltage direct current (HVDC) grids are envisioned for large-scale grid integration of renewable energy sources. Upon realization, components from multiple vendors have to be coordinated and interoperability problems can occur. To address these problems, a multi-vendor HVDC system can benefit from a partially open control and protection system. Unwanted interactions can be investigated and solved more easily in partially open software compared to when applying black-boxed and vendor-specific software. Although a partially open approach offers these advantages, practical aspects, such as the implementation in a real station architecture, have to be addressed carefully. This paper covers this important topic, first by reviewing the required control and protection functions and second by discussing the choice for certain open and closed software parts, their implementation in physical units as well as the required communication and interfaces. The result from this discussion is a first proposal of a station architecture for a multi-vendor HVDC system using partially open control and protection. This architecture will be a helpful starting point to industry and academia working with research and harmonization on this topic as ad-hoc solutions in terms of practical aspects can be avoided.
|
|
| 22. |
- Jahn, Ilka, et al.
(författare)
-
An Open-Source Protection IED for Research and Education in Multiterminal HVDC Grids
- 2020
-
Ingår i: IEEE Transactions on Power Systems. - : Institute of Electrical and Electronics Engineers (IEEE). - 0885-8950 .- 1558-0679. ; 35:4, s. 2949-2958
-
Tidskriftsartikel (refereegranskat)abstract
- The integration of large amounts of renewable energy will require multiterminal high-voltage direct-current (MTDC) grids to reliably transport the energy over long distances. However, before building an MTDC grid, a functional protection system design is needed. Realistic and industrial studies are required to validate the functionality of such a system. In addition, further academic research as well as education in the field are needed. This paper presents an open-source, low-cost protection intelligent electronic device (IED) prototype for use in a laboratory environment. In particular, the IED design, its fastest measured performance, example results for different fault scenarios, and an assessment of its use in education are shown. The open-source IED is useful to accelerate industrial and academic research, as well as to enable education in protection for MTDC grids.
|
|
| 23. |
- Jahn, Ilka, et al.
(författare)
-
Moving Beyond Open-Source Modelling : Why Open Control and Protection Software in Real Converters Will Be Useful
- 2022
-
Ingår i: 1st International Workshop on Open Source Modelling and Simulation of Energy Systems, OSMSES 2022 - Proceedings. - : Institute of Electrical and Electronics Engineers (IEEE).
-
Konferensbidrag (refereegranskat)abstract
- Software plays an essential role in the design and maintenance of the electric power system. To understand the studied phenomena and the underlying modelling tool, a certain degree of openness is needed. For that reason, open-source modelling has been gaining momentum regarding open (i.e., non-black-boxed) models and actual open-source modelling tools. However, the actual electric power system is also becoming more software-defined, in particular, due to the emergence of more and more power electronic converters. The control and protection software of power electronic converters can cause unwanted interactions in the power system. This paper provides an overview of such unwanted interactions and implemented solutions. Because of many unknowns in the changing power system, this paper argues that open control and protection software for power electronic converters can be a valuable complement to standardization.
|
|
| 24. |
- Jahn, Ilka
(författare)
-
Protection for Multiterminal HVDC Grids - A Digital Contribution
- 2021
-
Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The aim of this thesis is to (1) enhance understanding of mechanisms that are important for the protection of high-voltage direct-current (HVDC) grids, and (2) suggest possible technical solutions. To that end, digital technologies were used both in simulation, as well as in a laboratory environment.Literature studies were carried out on fault detection algorithms and substation communication leading to a recommendation to use a combination of single- and double-ended algorithms for fault detection, as well as to use the EtherCAT protocol for substation communication.A limitation of simulation studies are possible parameter uncertainties. For that reason, large protection margins by design are important. The simulation part of this thesis includes, firstly, a study concerning protection margins showing the detrimental effect of not being able to share information in a multi-vendor context. Secondly, a new method is presented for holistic protection system design taking into account a large variety of parameters and making sure that no hardware or software constraints are violated. For this, genetic optimization was found to be the most suitable technique. It is found that the holistic method is particularly useful for complex optimization problems, such as HVDC grids with different DC circuit breaker opening times and no converter blocking. In one test case, the genetic optimization resulted in a 71% decrease of total inductor size compared to the initial dimensioning provided by an engineer.Due to the destructive nature of faults, HVDC protection can obviously not be systematically tested full-scale or even in a laboratory environment. Still, real-time testing using real controllers or protection devices is useful because it is more realistic than offline, electromagnetic transient simulations. In this thesis, an intelligent electronic device (IED) prototype for HVDC grid protection was developed, providing a crucial device for subsequent studies on IED type testing and HVDC protection system testing, both of which were conducted outside of this PhD work. A test of the IED prototype with actual fault recordings from an operational HVDC link further increased confidence in HVDC protection, because the successful testing is based on both a real protection IED, and a real fault recording, and not a simulation that could be subject to inaccuracies.Finally, based on the need to share information during design of a multivendor HVDC protection system, as well as control-related problems reported from the field, a proposal for open-source HVDC control and protection is put forward, aiming to enhance vendor-interoperability.
|
|
| 25. |
- Jahn, Ilka, et al.
(författare)
-
Requirements for open specifications in multivendor HVDC protection systems
- 2020
-
Konferensbidrag (refereegranskat)abstract
- Integrating multiterminal high-voltage direct-current (HVDC) connections into the existing alternating current (AC) power transmission system is a possible solution for transport of large amounts of renewable energy. Protection is considered a key enabler for multiterminal HVDC (MTDC) grids. Designing such a protection system is a challenge, in particular in a multivendor setup. Fault detection during transients might be required to achieve the stringent speed requirements for HVDC protection. This in turn requires knowledge about the expected system behaviour during faults and involves knowledge from all vendors supplying equipment in MTDC grid. Traditionally, HVDC projects are, however, supplied as turn-key solutions and the control and protection systems are the intellectual property of the vendors and not open for the HVDC end-users. This paper aims to provide a starting point on the discussion which information has to be shared between vendorsand HVDC end-users when designing MTDC grid protection. Simulations results show that missing information about certain aspects can lead to a failure of the protection system. A discussion on organization of the available information is added. Open specifications of the used equipment are useful to design safe and reliable MTDC grid protection.
|
|
| 26. |
- Jahn, Ilka, et al.
(författare)
-
Testing of an HVDC IED Prototype Using Field Recordings
- 2021
-
Ingår i: 2021 23rd European Conference on Power Electronics and Applications, EPE 2021 ECCE Europe. - : Institute of Electrical and Electronics Engineers (IEEE).
-
Konferensbidrag (refereegranskat)abstract
- Testing of protection intelligent electronic devices (IEDs) for high-voltage direct-current (HVDC) systems is usually constrained to simulated HVDC faults because systematic testing with faults on full-scale HVDC systems is not feasible. However, all simulations are subject to inaccuracies. In this paper, an HVDC IED prototype is tested with real fault recordings from an operational point-to-point HVDC link. Firstly, the successful response of the prototype HVDC IED to fault recordings from a real system is presented. Secondly, the behaviour of different protection algorithms and filters is analysed, leading to conclusions about the applicability in a real system. The results are useful because the gained knowledge is based on both a real prototype HVDC IED and a real fault recording, and not a simulation.
|
|
| 27. |
- Jain, Rishabh, et al.
(författare)
-
Model-Based Design and System on Chip Implementation of DTC and PWM Techniques
- 2022
-
Ingår i: 2022 IEEE Delhi Section Conference, DELCON 2022. - : Institute of Electrical and Electronics Engineers (IEEE).
-
Konferensbidrag (refereegranskat)abstract
- This paper presents the implementation procedure of three Pulse Width Modulation (PWM) techniques and a closed-loop motor control method using a model-based design approach. The implemented PWM techniques are the Sinusoidal Pulse Width Modulation (SPWM), Space Vector Pulse Width Modulation (SVPWM), and Selective Harmonic Elimination Pulse Width Modulation (SHEPWM), whereas the closed-loop motor control method is the Direct Torque Control (DTC). These techniques are implemented using a ZedBoard development board which contains a System on a Chip (SoC) Xilinx Zynq-7000. The procedure of implementing these techniques on the ZedBoard and required considerations are discussed. The model-based design approach facilitates rapid implementation without prior knowledge of HDL and ARM programming, which makes it advantageous for students and research work. To verify the integrity of the implemented designs, the ZedBoard is used to control an induction machine (IM), and the results are presented.
|
|
| 28. |
- Johannesson, Daniel, et al.
(författare)
-
Evaluation of Ultrahigh-Voltage 4H-SiC Gate Turn-Off Thyristors and Insulated-Gate Bipolar Transistors for High-Power Applications
- 2021
-
Ingår i: IEEE transactions on power electronics. - : Institute of Electrical and Electronics Engineers (IEEE). - 0885-8993 .- 1941-0107. ; 37:4, s. 4133-4147
-
Tidskriftsartikel (refereegranskat)abstract
- Technology-based computer-aided design (TCAD) models have been used to predict the static and dynamic performance of ultrahigh-voltage (UHV) 4H-Silicon Carbide (SiC) PiN diodes, insulated-gate bipolar transistors (IGBTs), and gate turn-off (GTO) thyristors designed for 2050 kV blocking voltage capability. The simulated forward voltage drops of 2050 kV device designs range between 3.15.6 V for PiN diodes, 4.210.0 V for IGBTs, and 3.47.8 V for GTO thyristors at 20 A/cm2 for room temperature operation. Moreover, with a low switching frequency application (i.e., 150 Hz) in mind, the switching energy losses using an 30 kV SiC GTO thyristor design are approximately EON/EOFF_GTO = 268/640 mJ, EON/EOFF_FWD = 388/6 mJ diode recovery losses, and EON/EOFF_SNUB = 954/22 mJ snubber component losses. The corresponding values for a SiC IGBT design are EON/EOFF_IGBT = 983/748 mJ, both operated at 448 K, A = 20 s, and with 30 A/cm2. The simulation output is used in a benchmark evaluation for a 1 GW, 640 kV application case, employing modular multilevel high-power converter legs comprising series-connected UHV SiC devices and state-of-the-art 4.5 kV Si bi-mode insulated-gate transistors (BiGTs). It is concluded that the high-voltage SiC power electronic building blocks present promising alternatives to existing high-voltage Si device counterparts in terms of system compactness and efficiency.
|
|
| 29. |
- Johannesson, Daniel, et al.
(författare)
-
Static and Dynamic Performance Prediction of Ultra-High-Voltage Silicon Carbide Insulated-Gate Bipolar Transistors
- 2021
-
Ingår i: IEEE transactions on power electronics. - 0885-8993 .- 1941-0107. ; 36:5, s. 5874-5891
-
Tidskriftsartikel (refereegranskat)abstract
- The performance of theoretical ultra-high-voltagepower semiconductor devices has been predicted by means ofnumerical simulations using the Sentaurus technology computeraideddesign tool. A general silicon carbide punch-throughinsulated-gate bipolar transistor (IGBT) structure has beenimplemented with suitable physics-based models and parametersto reflect the device characteristics in a wide range of deviceblocking voltages from 20 to 50 kV. The models for 20 kV classIGBTs have been implicitly validated by means of publishedexperimental results. Mixed-mode simulations were performedthat predicted total switching energy loss densities of 335, 629,906 and 999 mJ/cm2 for 20, 30, 40 and 50 kV class devicesrespectively, at 25ºC, JC = 20 A/cm2 and an ambipolar carrierlifetime of 20 μs. While the IGBT on-state forward voltage dropreduces, the switching losses increase with higher charge-carrierlifetime for a given current density (e.g., 20 A/cm2). The largespan of simulation results will be used as an input support to thedesign of future high-power converters.
|
|
| 30. |
- Johannesson, Daniel
(författare)
-
Ultrahigh-Voltage Silicon Carbide Device Performance, Requirements, and Limitations in High-Power Applications
- 2021
-
Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The increased awareness of the on-going climate change accelerates the electric energy system transformation from fossil-fueled power sources towards systems with larger portions of renewable energy sources. Moreover, the grid infrastructure requires reinforcements to cope with increasing electrical energy demand. Flexible AC transmission systems (FACTS) and high-voltage DC (HVDC) transmission systems allow higher grid capacity, efficient transmission over long distances and sub-sea electrical energy transfer. Efficient sub-sea transmission is required for off-shore wind- and intercontinental grid connections. It is predicted that basic power electronic building blocks (PEBB) utilizing SiC-based semiconductor devices will provide converter system benefits (e.g., reduced number of series connected devices, less complex system, lower energy losses, lower cooling requirements and smaller station footprint), in comparison to systems employing Si-based semiconductor devices. The main objective of this thesis is to design, evaluate and identify the performance, requirements, and limitations of high-voltage SiC devices suitable for high-power applications. The SiC semiconductor device characteristics have been investigated by two-dimensional numerical simulations and experiments to assess the suitability in high-power applications. A calibrated set of technology computer-aided design (TCAD) simulation models are used as foundation for estimating the performance of SiC PiN diodes, SiC insulated-gate bipolar transistors (IGBTs) and SiC gate turn-off (GTO) thyristors with blocking voltage capabilities in the range of 20–50 kV. The static and dynamic device performances are assessed along with related gate driver requirements and snubber design requirements. The devices characteristic are studied using physical parameters of device layer structures, device processing parameters, and varying circuit parameters using mixed-mode simulations that results in a wide range of data for device performance predictability. Moreover, the experimental characterization of 10 kV, 100 A SiC metal-oxide semiconductorfield-effect transistor (MOSFET) power modules are demonstrated and compared to Si counterparts. The junction termination extension (JTE) design aspects for 20, 30, 40, and 50 kV devices are investigated where the results are used to predict the active area ratio for each blocking voltage class. In addition, the limit of critical operating conditions such as dynamic avalanche and current filamentation are derived by TCAD simulations, which indicates that the critical operation points are significantly higher than that of Si-based counterparts. The wide-range simulation data have been used in benchmarking SiC-based devices with Si counterparts in an application case of a 1 GW, 640 kV, modular multilevel converter (MMC)-based HVDC system. The analytical benchmark model indicates an energy loss reduction to approximately half by employing SiC device configurations compared to state-of-the-art Si bi-mode insulated gate transistors (BiGTs). The low energy losses along with the benefits by reduction of system complexity, control hardware, cables, and fibers (due to a lower amount of PEBBs), the SiC converter design presents a promising alternative to existing Si-based high-power modular multilevel converters.
|
|
| 31. |
- Johannesson, Daniel, et al.
(författare)
-
Wide-Range Prediction of Ultra-High Voltage SiC IGBT Static Performance Using Calibrated TCAD Model
- 2020
-
Ingår i: Materials Science Forum. ; , s. 911-916
-
Konferensbidrag (refereegranskat)abstract
- In this paper, a technology computer-aided design (TCAD) model of a silicon carbide (SiC) insulated-gate bipolar transistor (IGBT) has been calibrated against previously reported experimental data. The calibrated TCAD model has been used to predict the static performance of theoretical SiC IGBTs with ultra-high blocking voltage capabilities in the range of 20-50 kV. The simulation results of transfer characteristics, IC-VGE, forward characteristics, IC-VCE, and blocking voltage characteristics are studied. The threshold voltage is approximately 5 V, and the forward voltage drop is ranging from VF = 4.2-10.0 V at IC = 20 A, using a charge carrier lifetime of τA = 20 μs. Furthermore, the forward voltage drop impact for different process dependent parameters (i.e., carrier lifetimes, mobility/scattering and trap related defects) and junction temperature are investigated in a parametric sensitivity analysis. The wide-range simulation results may be used as an input to facilitate high power converter design and evaluation. In this case, the TCAD simulated static characteristics of SiC IGBTs is compared to silicon (Si) IGBTs in a modular multilevel converter in a general highpower application. The results indicate several benefits and lower conduction energy losses using ultra-high voltage SiC IGBTs compared to Si IGBTs.
|
|
| 32. |
- Johannesson, Niclas
(författare)
-
Multi-terminal HVDC protections based on transient line modeling
- 2022
-
Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- High voltage direct current (HVDC) is considered one of the critical technologies required for the power system to enable the transition toward renewables. With an increasing geographical density of HVDC converters, there is a potential for optimization by connecting more than two converters into a shared DC transmission system, thus forming a multi-terminal HVDC (MTDC) system.Larger MTDC systems are expected to require HVDC circuit breakers, thereby allowing disconnection of system subsections in case of faults rather than a complete shutdown of all converters. Thus, the protection system in MTDC systems with DC breakers differs from a conventional point-to-point system, as differentiation between DC faults is required to ensure that only the minimum subsection of the system is disconnected in the event of a fault. The main topic of this thesis is to achieve reliable detection of DC line faults (i.e., underground/submarine cables or overhead lines) in MTDC systems.In this thesis, two different methods are proposed. The first is based solely on locally obtained measurements, thus requiring a reactor at the opposite end to provide a boundary of the protection zone. The method extracts the incident traveling wave using time-domain modeling techniques to represent the frequency-dependent characteristic admittance, thereby making it independent of line terminal reflections. Differentiation between internal and external faults is achieved by determining the steepness of the incident wave-front.The second method, traveling wave differential protection, requires telecommunication between the two ends of a line, thereby not requiring a reactor to differentiate between internal and external faults. The method is based on a differential calculation of traveling waves obtained from voltages and currents at both ends and the frequency-dependent representations of the characteristic admittance and propagation function. Compared with other telecommunication-based methods, it is found that the method can operate faster because of the included wave propagation time in the differential calculation. The traveling wave differential protection relies on the transmission line parameters to accurately calculate and compare the traveling waves at both ends of a line. Thus, parameter errors will result in a false non-zero differential current during external disturbances, potentially causing false operation and reducing reliability. Therefore, the method's sensitivity was evaluated in a cable application using a procedure to automatically generate cable models with parameter variations and perform a transient simulation of an external fault. It was found that the propagation time used for synchronizing the waves in the differential calculation was the most critical parameter. Therefore, a method was developed to minimize any time-shift errors that otherwise would result in a false differential current.
|
|
| 33. |
- Johannesson, Niclas, et al.
(författare)
-
Sensitivity of Cable Model Parameters for Traveling Wave Differential Protections in MTDC Systems
- 2020
-
Ingår i: IEEE Transactions on Power Delivery. - : Institute of Electrical and Electronics Engineers (IEEE). - 0885-8977 .- 1937-4208. ; 35:5, s. 2212-2221
-
Tidskriftsartikel (refereegranskat)abstract
- Multi-terminal HVDC systems equipped with multiple DC breakers require a protection system that selectively detects faults within a few milliseconds. In the development and application of such protection algorithms, time-domain simulation studies of various faults are essential when determining the setting and verifying the performance. However, when such protections are applied in practice, it should be expected that the models will not perfectly represent the behavior of the real system or transmission line, thereby possibly causing protections to operate unreliably. This paper presents a simulation process that evaluates the consequences for a protection algorithm when the transmission line parameters are varied. More specifically, the false differential current due to cable model parameter errors is evaluated in a traveling-wave differential protection applied in a multi-terminal HVDC system during an external fault. The purpose is to identify the most critical parameters and evaluate how inaccuracies influence the protection performance when applied in practice. It is shown that the parameters which significantly influence the propagation delay are critical for achieving the ideal performance - a strictly zero differential current during external faults.
|
|
| 34. |
- Nahalparvari, Mehrdad, et al.
(författare)
-
AC-Side Impedance-Based Stability Assessment in Grid-Forming Modular Multilevel Converters
- 2024
-
Ingår i: IEEE Access. - : Institute of Electrical and Electronics Engineers (IEEE). - 2169-3536. ; 12, s. 23514-23528
-
Tidskriftsartikel (refereegranskat)abstract
- Grid-forming converters can emulate the behavior of a synchronous generator through frequency droop control. The stability of grid-forming modular multilevel converters can be studied via the impedance-based stability criterion. This paper presents an ac-side impedance model of a grid-forming modular multilevel converter which includes a complete grid-forming control structure. The impact of different control schemes and parameters on the closed-loop output impedance of the converter is thoroughly analyzed and the learnings have been used in mitigating undesired control interactions with the grid. The results are verified through simulations in time- and frequency-domains along with experiments on a down-scaled laboratory prototype.
|
|
| 35. |
- Nahalparvari, Mehrdad, et al.
(författare)
-
DC-Side Impedance Estimation of a Modular Multilevel Converter Through System Identification of a Partially Black-Boxed Control System
- 2022
-
Ingår i: IEEE transactions on energy conversion. - : Institute of Electrical and Electronics Engineers (IEEE). - 0885-8969 .- 1558-0059. ; 37:4, s. 2708-2721
-
Tidskriftsartikel (refereegranskat)abstract
- The stability of a power electronics system can be assessed by means of the impedance-based stability criterion. Impedance modeling is a useful tool to analyze the effect of different circuit parameters and control schemes on the behavior of a converter. Modeling the input impedance of a power electronics converter is often successful when having full knowledge of the converter topology, the circuit parameters, and the parameters and implementation of the control system. However, due to the proprietary nature of voltage source converter-based high voltage direct current systems, their exact control structure is often concealed. This complicates the calculation of the impedance of a modular multilevel converter, known for its complex internal dynamics. This paper proposes a method to estimate the impedance of a modular multilevel converter with partially black-boxed converter control. A discussion on partitioning the control system into open and closed parts is made, and the results are verified with simulations in time and frequency domains.
|
|
| 36. |
- Nahalparvari, Mehrdad, et al.
(författare)
-
DC-Side Impedance Interaction Analysis in an MMC-Based Back-to-Back VSC-HVDC System
- 2021
-
Ingår i: IECON 2021 - 47Th Annual Conference Of The Ieee Industrial Electronics Society. - : Institute of Electrical and Electronics Engineers (IEEE).
-
Konferensbidrag (refereegranskat)abstract
- In this paper, harmonic stability of a back-to-back modular multilevel converter based voltage source converter high voltage direct current system is analyzed. These systems are prone to ac- and dc-side resonances and interactions between the converter and its interconnected systems. The stability of the system can be predicted by the impedance based stability criterion, which requires the modeled or measured converter impedance. The analysis in this paper focuses on interoperability when the converters employ different control schemes in order to utilize the inherent damping properties of the sum capacitor voltage balancing control loops.
|
|
| 37. |
- Nahalparvari, Mehrdad, et al.
(författare)
-
DC-Side Impedance Modeling and Stability Assessment in Grid-Forming Modular Multilevel Converters
- 2023
-
Ingår i: 2023 25th European Conference on Power Electronics and Applications, EPE 2023 ECCE Europe. - : Institute of Electrical and Electronics Engineers (IEEE).
-
Konferensbidrag (refereegranskat)abstract
- Incorporation of inverter-based resources is progressively increasing in modern power systems. The absence of inherent physical inertia in converter-based systems has resulted in a decrease in the total inertia of the grid. Grid-forming control of voltage source converters emulates the workings of a conventional synchronous generator through frequency droop control, allowing the converter to provide inertial support while contributing to the support of grid voltage. This paper presents a dc-side impedance model of a grid-forming modular multilevel converter. A control interaction between a grid-forming and a grid-following converter in a back-to-back structure is investigated and a stabilizing compensator is proposed.
|
|
| 38. |
- Norrga, Staffan, 1968-, et al.
(författare)
-
DC Interconnection of Adjacent Point-to-Point HVDC Links as an Enabling Step towards Deployment of Multiterminal HVDC Systems
- 2022
-
Ingår i: Proceedings CIGRE Session 2022. - : CIGRE.
-
Konferensbidrag (refereegranskat)abstract
- A transition from point-to-point HVDC links to multiterminal systems can save much investment cost, since the number of converter stations can be reduced. In addition, security of supply is improved since power can be routed in alternative paths in case of a converter or cable fault. Grid losses and unavailability are reduced as power flows through fewer converters. Finally, using fewer converters also reduces the environmental and visual impact as well as the planning and permitting issues. The equipment required for implementing multiterminal HVDC networks is rapidly gaining technical maturity. Several feasible solutions for DC circuit breakers (DCCBs) exist and have been demonstrated. Standardisation and testing of the DCCBs has evolved greatly. Furthermore, the development of controland protection methods for multiterminal systems has taken great strides recently. Still, however, the actual deployment of multiterminal or meshed HVDC systems has been almost non-existent outside China. The main reason is that HVDC operators wanting to benefit from multiterminal HVDC systemsface a vicious circle: practical experience in multiterminal HVDC is lacking, but cannot be gained because of the risks associated with a deployment when there is insufficient experience. The question is, therefore, how the risks can be mitigated. This paper proposes to create a direct DC connection between two existing, or planned, point-to-point HVDC links which both terminate in the same location. A particular case, involving the two links the SouthWest Link in Sweden, and the Hansa Power Bridge, linking Sweden and Germany, is studied in detail. By the proposed methodology, multiterminal operation and protection aspects can be verified at full scale at minimum risk. In the unlikely event that multiterminal operation cannot be achieved it is always possible to operate the links as point-to-point, i.e., as initially intended. The paper investigates several aspects of the proposed DC connection. First, a technical analysis looks into the load-flow and protection aspects. Notably, the combined system differs from multiterminal systems studied in literature in that there are several converters at the middle node and that both point-to-point and multiterminal operation should be possible. Load flow is managed by a power and voltage droop control of the converter stations. For protection, DCCBs will be employed in the DC connection, to ensure unimpeded operation of one of the links in case of a fault on the other link. The study considers two different types of DCCBs: hybrid and mechanical. These differ in terms of cost and speed ofoperation. A multitude of simulations verifies the function of the protection scheme. Furthermore, a detailed cost-benefit analysis (CBA) looks into the economic aspects of the DCconnection. Apart from the CAPEX and the running cost, the CBA indicates the substantial saving resulting from avoiding converter losses for power routed directly between the end nodes. Moreover, an expected improvement in availability of the overall link is shown. Several scenarios with regard to the power flows are evaluated. In addition, the socioeconomic welfare gain and the redispatch savings are considered. The mentioned cost savings could make the DC connection profitable. Finally, the legal and regulatory aspects of the DC connection are also evaluated considering that eventhough the DC connection will be located on Swedish territory it would also influence socioeconomic welfare in Germany.
|
|
| 39. |
- Sharifabadi, Kamran, et al.
(författare)
-
Open-Source HVDC Control – a High-Level Perspective
- 2020
-
Konferensbidrag (refereegranskat)abstract
- Future multivendor, and multiterminal high-voltage direct-current (HVDC) grids are considered an enabling technology to efficiently integrate large amounts of renewable energy into the existing grid. However, already in today's existing point-to-point HVDC links, control and harmonic interaction issues and instabilities related to the control and protection system of the converters have been reported. The converter control software is usually black-boxed and issues are therefore solved in close cooperation with the HVDC vendor. This paper discusses a possible paradigm shift in HVDC technology: an open-source HVDC control system. In particular, it covers the control design including technical and non-technical aspects. The open-source approach can be useful to solve current as well as future control-related problems, both in point-to-point links as well as in multiterminal, and multivendor HVDC grids.
|
|
| 40. |
- Singh, B. P., et al.
(författare)
-
Analysis of the Performance of Different Packaging Technologies of SiC Power Modules during Power Cycling Test
- 2023
-
Ingår i: 2023 29TH INTERNATIONAL WORKSHOP ON THERMAL INVESTIGATIONS OF ICS AND SYSTEMS, THERMINIC. - : Institute of Electrical and Electronics Engineers (IEEE).
-
Konferensbidrag (refereegranskat)abstract
- Commercialization of SiC MOSFETs and electrification of the automotive sector has resulted in the accelerated development of power semiconductor devices. To take the most advantage of the SiC properties and make the power semiconductor modules automotive graded, the power module packaging technologies are developing at a rapid pace. New materials are being introduced and more innovative ways are being investigated to operate the SiC die at high temperatures while maintaining high reliability. Silver (Ag) sinter, due to its superior properties, has been introduced as a state-of-the-art die-attaching technology, while different ways are being investigated to either eliminate the aluminium (Al) bondwires or replace them with copper (Cu) counterparts. In this study, we will use the Finite Element (FE) method to investigate the impact of different packaging aspects like using copper foil and Ag sinter on thermal and mechanical performance of the power module. We will also investigate the effect of different packaging on power module reliability.
|
|
| 41. |
- Singh, Bhanu Pratap, et al.
(författare)
-
Analysis of the Thermo-mechanical Performance of Double-Sided Cooled Power Modules
- 2024
-
Ingår i: 2024 25th International Conference on Thermal, Mechanical and Multi-Physics Simulation and Experiments in Microelectronics and Microsystems, EuroSimE 2024. - : Institute of Electrical and Electronics Engineers (IEEE).
-
Konferensbidrag (refereegranskat)abstract
- Double-sided cooled (DSC) power semiconductor modules have garnered increased interest over the past decade due to their ability to offer an additional path for heat removal, facilitating higher power density operation while reducing junction temperatures and thermal stresses. Nevertheless, when operating at similar junction temperatures, DSC modules might exhibit elevated thermo-mechanical stress compared to single-sided cooled (SSC) modules. This increase can be attributed to restricted vertical movement within the DSC modules. Furthermore, the integration of various spacers within the DSC modules, which enable bond wire connections to gate terminals, can significantly influence both the thermal performance and induced thermo-mechanical stresses. Depending on the materials used in the spacer, the thermal performance and thermo-mechanical stresses inside the module can vary. In this study, we have first analysed the thermal performance of the DSC power modules employing different spacers. Following that, we have also performed thermo-mechanical analysis in different solder layers. Finally, fatigue analysis is done to demonstrate the weakest solder layer inside the package.
|
|
| 42. |
- Singh, Bhanu Pratap, et al.
(författare)
-
Analyzing the Impact of Die Positions inside the Power Module on the Reliability of Solder Layers for Different Power Cycling Scenarios
- 2023
-
Ingår i: 2023 24th International Conference on Thermal, Mechanical and Multi-Physics Simulation and Experiments in Microelectronics and Microsystems, EuroSimE 2023. - : Institute of Electrical and Electronics Engineers (IEEE).
-
Konferensbidrag (refereegranskat)abstract
- Solder layers, used as bonding material inside the power module to attach the semiconductor die on Direct Bond Copper (DBC) substrate and DBC substrate on baseplate, are one of the regions most prone to failure. The failure usually occurs in the form of solder cracks and depends on various operating conditions, such as-maximum temperature, temperature swing, and heating time. The cracks generated inside the solder layers can eventually result in its delamination. Power modules are usually power cycled to estimate the failure sites and mechanisms. However, the failure mechanisms can vary depending on the frequency, amplitude, and range of the temperature in the Power Cycling Tests (PCT). In this study, we have used the Finite Element Method (FEM) in COMSOL Multiphysics to analyse the impact of the PCT on both die attach, and baseplate attach solder layers. Additionally, the effect of the degree of asymmetry in the die position on the reliability of both the solder layers are analysed. The FEA (Finite Element Analysis) results are analysed to have a better understanding about the aspects impacting the lifetime of the power module.
|
|
| 43. |
- Singh, B. P., et al.
(författare)
-
Change in SiC MOSFET body-diode voltage drop in TO-247 packages during inverse-mode and forward-mode power cycling test
- 2022
-
Ingår i: ETG-Fachbericht. - : VDE Verlag GmbH. ; , s. 423-428
-
Konferensbidrag (refereegranskat)abstract
- Body-diode voltage drop has been identified as a reliable parameter for both as a temperature-sensitive electrical parameter (TSEP) to estimate the SiC MOSFET junction temperature and as a failure precursor to identify any package related degradation. However, in the inverse-mode power-cycling test (PCT), it is found that the body-diode voltage drop changes at a fixed temperature. It is known from the previous research that the increase in a body-diode voltage drop at heating current acts as a failure precursor, indicating package related degradation. However, the change in the voltage drop at a low measurement current, due to degradation, is not well investigated. This study aims to analyse how the body-diode voltage drop at low current changes in TO-247 packaged SiC MOSFETs during inverse and forward-mode PCT.
|
|
