| 1. |
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| 2. |
- Ahlgren, Erik, 1962, et al.
(författare)
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Produktionsrelaterade systemstudier
- 2006
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- I denna rapport, Produktionsrelaterade systemstudier – flexibla el- och värmesystem, har kortfattat ett antal områden som kan tänkas få betydelse för utvecklingen av de svenska el- och värmeförsörjningssystemen analyserats. Målet har varit att ge en bakgrundsbeskrivning av ett antal tekniska och teknisk-ekonomiska områden som kommer att påverkas av och/eller påverka framtida el- och värmeförsörjning. Författarna har utgått från de övergripande frågorna, såsom försörjningstrygghet i en avreglerad marknad och energisektorns miljöpåverkan speciellt med avseende på klimatpåverkan. Systemgränsen runt el- och värmesektorn har avsiktligt dragits mycket brett så att också bebyggelse- och industrisektorerna är inkluderade, eftersom dessa är de klart dominerande sektorerna både med avseende på elanvändning och med total energianvändning. Avsikten med detta har varit att peka på den stora betydelse som ändrade energiefterfrågemönster inom bebyggelsesektorn och än annan syn på industrisektorn, inte bara som energianvändare utan också delvis som energileverantör, kan få för det framtida el- och värmeförsörjningssystemet. Studien behandlar produktionsrelaterade elsystemfrågor, men med ett perspektiv av interaktion mellan tillgång och efterfrågan. Ett stort antal tillförseltekniker och –system har kort berörts. Vissa av dessa dominerar systemet idag, andra kan tänkas få en inte oväsentlig betydelse i framtida system. Genomgående trycks på behovet av en integrerad analys där hänsyn tas till samspel mellan tillförsel och användning, mellan teknik och ekonomi, mellan kort och lång sikt, mellan el och värme och även transporter, för att uppnå en högre verkningsgrad och därmed minskad miljöbelastning. Verkningsgraden har betraktats utgående från ett systemperspektiv snarare än från ett anläggnings-perspektiv. Slutsatsen av analysen är att det fortfarande finns ett antal markanta kunskapsluckor, och att dessa framför allt finns på systemnivå i samspelet, eller det möjliga samspelet, mellan ovan nämnda områden; tillförsel och användning; el, värme och transporter; samt betydelsen för försörjningssystemet av förväntade ändringar med tiden av såväl el- och värmeefterfrågan, som av tillgängliga tekniska lösningar.
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| 3. |
- Altintas, Atilla, 1979, et al.
(författare)
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Forecasting of Day-Ahead Wind Speed/electric Power by Using a Hybrid Machine Learning Algorithm
- 2023
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Ingår i: Lecture Notes of the Institute for Computer Sciences, Social-Informatics and Telecommunications Engineering. - 1867-8211 .- 1867-822X. ; 502 LNICST, s. 3-11
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Konferensbidrag (refereegranskat)abstract
- The amount of energy that has to be delivered for the following day is currently predicted by power system operators using day-ahead load forecasts. With the use of this forecast, generation resources can be committed a day in advance, some of them may require several hours’ notice to be ready to produce power the following day. In order to determine how much wind power will be available for each hour of the following day, power systems with large penetrations of wind generation rely on day-ahead predictions. The main objective of this study is to improve the day-ahead forecasting of wind power by improving the forecasting method using machine learning. A hybrid approach, which combines a mode decomposition method, Empirical Mode Decomposition (EMD), with Support Vector Regression (SVR), is used. The results suggest that using Support Vector Regression together with the hybrid method, which includes the Empirical Mode Decomposition to predictions can improve the accuracy of predictions. Higher accuracy forecasting of wind power is expected to improve the planning of dispatchable energy generation and pricing for the day-ahead power market.
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| 4. |
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| 5. |
- Antoniadou-Plytaria, Kyriaki, 1989, et al.
(författare)
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Chalmers Campus as a Testbed for Intelligent Grids and Local Energy Systems
- 2019
-
Ingår i: IEEE International Conference on Smart Energy Systems and Technologies (SEST). - 9781728111568
-
Konferensbidrag (refereegranskat)abstract
- This paper presents an overview of a testbed for intelligent distribution grids, local energy systems, and energy flexible buildings, which is being developed at the campus of Chalmers University of Technology in Gothenburg, Sweden. It describes the test sites, the functionalities, and the planned demonstration activities within the scope of on-going research projects. The proposed demonstrations include a local energy market platform, energy management solutions for microgrids and smart buildings, as well as voltage control in distribution grids. The paper aims to show how the physical energy supply systems of the university are being adapted to integrate the communication and control set-ups that provide the technical requirements for smart grid interoperability. As an example, the on-site implementation of remote battery control is presented, where initial results show the feasibility and potential benefits of the external control. Finally, challenges and lessons learned during the development of the testbed are highlighted.
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| 6. |
- Antoniadou-Plytaria, Kyriaki, 1989, et al.
(författare)
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Effect of Short-term and High-resolution Load Forecasting Errors on Microgrid Operation Costs
- 2022
-
Ingår i: IEEE PES Innovative Smart Grid Technologies Conference Europe. - 9781665480321 ; 2022-October
-
Konferensbidrag (refereegranskat)abstract
- The aim of this paper is to evaluate the effect of the load forecasting errors to the operation costs of a grid-connected microgrid. To this end, a microgrid energy scheduling optimization model was tested with deterministic and stochastic formulations under two solution approaches i.e., day-ahead and rolling horizon optimization. In total, twelve simulation test cases were designed receiving as input the forecasts provided by one of the three implemented machine learning models: linear regression, artificial neural network with backpropagation, and long short-term memory. Simulation results of the weekly operation of a real residential building (HSB Living Lab) showed no significant differences among the costs of the test cases for a daily mean absolute percentage forecast error of about 12%. These results suggest that operators of similar microgrid systems could use simplifying approaches, such as day-ahead deterministic optimization, and forecasts of similar, non-negligible accuracy without substantially affecting the microgrid's total cost as compared to the ideal case of perfect forecast. Improving the accuracy would mainly reduce the microgrid's peak power cost as shown by its 20.2% increase in comparison to the ideal case.
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| 7. |
- Antoniadou-Plytaria, Kyriaki, 1989, et al.
(författare)
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Energy Scheduling Strategies for Grid-connected Microgrids: A Case Study on Chalmers Campus
- 2019
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Ingår i: Proceedings of 2019 IEEE PES Innovative Smart Grid Technologies Europe, ISGT-Europe 2019.
-
Konferensbidrag (refereegranskat)abstract
- This paper focuses on the optimal energy management of grid-connected microgrids with battery energy storage systems. The microgrid energy management and the optimal power flow of the distribution network are formulated as mixed-integer linear optimization problems to evaluate microgrid energy scheduling strategies including cost minimization, maximum use of own resources, and minimum energy exchange with the upstream network. The real distribution network of Chalmers University of Technology campus is used as a case study. The study results show that economic optimization yields an annual microgrid cost reduction of 4%. Alternatively, if the microgrid minimizes the energy exchange, virtual islanding operation (zero energy exchange) for 3211 hours can be achieved within a year. The results also present the effects on the operation and cost of the distribution system and highlight a trade-off between microgrid cost minimization and battery lifetime.
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| 8. |
- Antoniadou-Plytaria, Kyriaki, 1989, et al.
(författare)
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Market-based Energy Management Model of a Building Microgrid Considering Battery Degradation
- 2021
-
Ingår i: IEEE Transactions on Smart Grid. - 1949-3053 .- 1949-3061. ; 12:2, s. 1794-1804
-
Tidskriftsartikel (refereegranskat)abstract
- This paper presents a model for energy management system of a building microgrid coupled with a battery energy storage. The model can be used to dispatch the battery as a flexible energy resource using a market-based setting. The battery is modeled considering battery degradation and real-life operation characteristics derived from measurements at a residential building. The performance of the model was evaluated first with simulations and integrated afterwards to an energy management system, which was demonstrated at a real residential building (HSB Living Lab) equipped with photovoltaic and battery storage systems. The simulation results showed that the building owner, and subsequently the residents, could benefit from the proposed model in reduced annual cost up to 3.1% under the considered pricing scheme. The demonstration results showed that dispatch under the measurement-based model could decrease the undelivered energy over the daily requested amount from the battery from 13.3% to 3.7%. Thus, the proposed model, which couples the measurement-based dispatch with battery degradation, can lead to a more accurate estimation of the building operation cost and an improved overall performance of battery as a flexible resource in building microgrids.
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| 9. |
- Antoniadou-Plytaria, Kyriaki, 1989, et al.
(författare)
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Scenario-based Stochastic Optimization for Energy and Flexibility Dispatch of a Microgrid
- 2022
-
Ingår i: IEEE Transactions on Smart Grid. - 1949-3053 .- 1949-3061. ; 13:5, s. 3328-3341
-
Tidskriftsartikel (refereegranskat)abstract
- Energy storage is one of the most important components of microgrids with non-dispatchable generators and can offer both energy and flexibility services when the microgrid operates in grid-connected mode. This paper proposes a scenario-based stochastic optimization model that can be used to determine the energy and flexibility dispatch of a residential microgrid with solar and stationary battery systems. The objective of the model is to minimize the expected energy and peak power cost as well as the battery aging cost, while maximizing the expected revenue from flexibility. The formulated stochastic optimization problem is solved in rolling horizon with the uncertainty model being dynamically updated to consider the most recent forecast profiles for solar power and electricity demand. The benefits of the proposed approach were demonstrated by simulating the daily operation of a real building. The results showed that the estimated flexibility was successfully dispatched yielding an economic value of at least 7% of the operation cost of the building microgrid. The model can be used by flexibility providers to assess their flexibility and design a bidding strategy as well as by system operators to design incentives for flexibility providers.
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| 10. |
- Babaei, Saman, et al.
(författare)
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Effects of PHEVs in power distribution systems: reviews and analyses
- 2010
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Ingår i: CIRED Workshop on Sustainable Distribution Asset Management and Financing, 7-8 June 2010, Lyon, France.
-
Konferensbidrag (refereegranskat)abstract
- This paper deals with the analysis of the impacts of plug-in hybrid electric vehicles (PHEVs) on the power system, with focus on the low voltage power distribution system. First a review of the technical challenges in the power system due to the mass introduction of PHEVs in the transportation sector is given. Then the paper shows on an analysis of the overloading effects of PHEVs on the distribution system with normal charging and quick charging of PHEVs for an IEEE 13-node distribution test system using power flow analysis. The results of the study show that introduction of PHEVs in the transportation sector will lead to overloading of distribution system and cause voltage problems at the end-users. The paper also analyzes the effects of PHEVs in the transmission system, using the Nordic 32-bus test system. The study results showed that the overloading problem is not prominent. However, one interesting and important result is that PHEVs may lead to overvoltages in some buses in the transmission system which requires the voltage control measures. PHEVs would also lead to increased number of network violations in the contingency analysis.
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| 11. |
- Babaei, Saman, et al.
(författare)
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Effects of Plug-in Electric Vehicles on Distribution Systems: The Real Case of Gothenburg
- 2010
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Ingår i: IEEE PES Conference on Innovative Smart Grid Technologies Europe, Gothenburg, Sweden, October 10-13, 2010. - 9781424485109
-
Konferensbidrag (refereegranskat)abstract
- The electric power system is changing and, especially, the electrical distribution system will meet new features. One of the large changes is a transformation of the transportation sector with the use of electricity, with introduction of electrical vehicles and Plug-in Electric Vehicles (PEVs). This will pose new challenges and opportunities for the electric distribution companies. This paper analyzes the effects of PEVs charging on the local 400 V and 10 kV electric distribution systems in the city of Gothenburg, Sweden, using steady-state power flow analysis. Two different areas representing residential area and commercial area have been simulated for the worst-case scenario, which is simultaneous charging of all the vehicles during the peak load period. The number of PEVs used has been estimated based on the load level at each customer location. The study results have shown that overloading of lines would occur when simultaneous charging of the vehicles during the peak load period. There would, however, be no problem with the voltage drop at the customer’s location during PEVs charging. An iterative method is proposed to estimate the maximum number of possible vehicles charging in the distribution system without resulting in any line overloaded. This method is also applied when one of the feeders is on outage to ensure the N-1 reliability criterion.
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| 12. |
- Balram, Pavan, 1986, et al.
(författare)
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Comparative study of MPC based coordinated voltage control in LV distribution systems with photovoltaics and battery storage
- 2018
-
Ingår i: International Journal of Electrical Power and Energy Systems. - : Elsevier BV. - 0142-0615. ; 95, s. 227-238
-
Tidskriftsartikel (refereegranskat)abstract
- This paper compares traditional local voltage control strategy with coordinated, optimization-based ones in LV distribution systems with photovoltaics and battery energy storage systems. Optimization-based strategies are formulated within a model predictive control (MPC) framework. Three strategies based on MPC are proposed and implemented, namely, centralized, decentralized and distributed MPC. The formulated strategies for voltage control are compared in a case study using a modified CIGRE European 3-area low-voltage network. Results indicate that decentralized MPC gives a better voltage profile in the network when compared to local voltage control strategy, since the latter inherently fails to maintain voltages of buses in the network not connected to photovoltaics or battery storage system within limits. Centralized MPC strategy is able to provide the optimal voltage profile across the network but utilizes 13% higher reactive power from the control devices to achieve this when compared to decentralized MPC. The latter performs well as long as the reactive power reserves within an area is sufficient but faces drawbacks similar to that of local voltage control strategy when the reactive reserves are completely exhausted. Distributed MPC utilizes 1:3% higher amount of reactive power reserves compared to centralized MPC in order to provide a network voltage profile similar to that of the latter while also yielding architectural advantages of decentralized MPC.
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| 13. |
- Balram, Pavan, 1986, et al.
(författare)
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Demonstration of Voltage Control in a Real Distribution System using Model Predictive Control
- 2017
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Ingår i: IET Generation, Transmission and Distribution. - : Institution of Engineering and Technology (IET). - 1751-8687 .- 1751-8695. ; 11:16, s. 3922-3929
-
Tidskriftsartikel (refereegranskat)abstract
- This paper presents the results from field tests that were carried out with the aim of verifying the performance of a model predictive control-based voltage controller. A voltage source converter capable of producing or consuming 4 MVAr was used as the reactive power source, which was able to influence the voltage magnitude at a remote bus within a real distribution system in Gothenburg, Sweden. The voltage controller is designed to maintain the remote bus voltage within a pre-defined range while respecting the reactive power output capability of the voltage source converter and an objective of minimum changes to the reference value of its local reactive power controller. Results from the field tests demonstrate that the voltage controller was able to successfully regulate the voltage even with significant errors in the state-space prediction model. An important lesson learned from the field test is that a smoothened voltage measurement feedback is critical to a satisfactory functioning of the controller. Furthermore, it is recommended to design the voltage controller to observe an initial delay, before it is activated for bus voltage control- this would deter it from unnecessarily reacting at the very instant it is brought online.
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| 14. |
- Balram, Pavan, 1986, et al.
(författare)
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Predictive voltage control of batteries and tap changers in distribution system with photovoltaics
- 2016
-
Ingår i: Power Systems Computation Conference (PSCC). - 9788894105124
-
Konferensbidrag (refereegranskat)abstract
- This paper proposes a model predictive control approach for coordinated secondary voltage control of on-load tap changing transformers and battery energy storage systems in a distribution system to maintain the bus voltage levels in the presence of photovoltaic generation. Optimal control actions are obtained based on a quadratic objective function with linear constraints. The control actions are implemented in a case study using a modified CIGRÉ European low voltage distribution network with corresponding models of the constituent devices and their local controllers. The results indicate that battery energy storage system could aid the system voltages and reduce the number of transformer tap operations if the control is performed in a coordinated manner enabled by the model predictive control framework.
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| 15. |
- Bertling, Lina, 1973, et al.
(författare)
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Integration of plug in hybrid electric vehicles and electric vehicles - Experience from Sweden
- 2010
-
Ingår i: Power and Energy Society General Meeting, 2010 IEEE. - 9781424483570
-
Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- Integration of plug in hybrid electric vehicles and electric vehicles (PHEVs and EVs) includes a wide area of topics like grid effects, different charging concepts, charger designs, harmonics from the charger etc. This short paper gives an introduction to ongoing work within this field in Sweden, and shows on research work within the topic at Chalmers University of Technology. ©2010 IEEE.
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| 16. |
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| 17. |
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| 18. |
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| 19. |
- Carlson, Ola, 1955, et al.
(författare)
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Development and Demonstration of New Technology for the use of Wind Turbines on Ships
- 2014
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- Technology to substantially reduce commercial ship fuel consumption by harnessing sea winds forsimultaneous generation of electricity and thrust, has been developed by the company PROPit AB.The basic idea is to apply conventional wind turbine technology for the marine environment, wherethe turbine will also take the function of sails. Primary target market is tankers or bulk ships with alarge and open deck space. Chalmers, in a study co-sponsored by the Swedish Energy Agency andChalmers Energy Centre, 2011, confirmed fuel saving estimates around 15-30 % for optimal routes,but with higher uncertainties.
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| 20. |
- Carlson, Ola, 1955, et al.
(författare)
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Grid Code Testing of Wind Turbine by VSC-based Test Equipment
- 2017
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Ingår i: Wind Energy Science Conference 2017, DTU Lyngby, June 2017.
-
Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- To fulfill the EU target of large amount of wind power in the electric power system, several technical barriers have to be overcome. The main challenge for the wind energy development is to make the wind turbines efficient in respect of costs and safe operation. An important design criterion is the fulfillment of the Grid Codes given by the transmission system operators. The Grid Codes state how wind turbines/farms must behave when connected to the grid in normal and abnormal conditions. In this regard, wind turbine manufactures must show how well their wind turbines can withstand an abnormal condition. This is done by simulations and some simplified tests. Tests of the Grid Code compliance for voltage dips in the grid are today carried out by use of coils and contactors mounted in a container that is connected between the wind turbine and the grid. This equipment has limited testing capability while been able to test only a part of the technical requirements given in the Grid Codes. For example, wind turbine operation with the grid frequency of 49 Hz cannot be tested, but still the requirement exists in today´s Grid Codes. Another solution to realize the grid code tests is to use fully-rated Voltage Source Converter (VSC) in back-to-back configuration. By controlling the turbine-side output of the converter system, a wider spectrum of grid faults can be emulated. Thanks to the full controllability of the applied voltage in terms of magnitude, phase and frequency, the use of VSC-based testing equipment, provides more flexibility as compared with the standard impedance-based test equipment. In addition, the AC grid is decoupled from the tested object when performing the test; meaning that the strength of the grid is not a major limitation. The test results are from the test of the 4 MW wind turbine and the 8 MW test equipment, located in Gothenburg, Sweden. In the tests the wind turbine operates at rated power when the voltage dip is applied. The turbine copes very well with the dip while a minor influence on the current and in the reactive and active power is observed.
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| 21. |
- Carlson, Ola, 1955, et al.
(författare)
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Harnessing energy flows: technologies for renewable power production
- 2014
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Ingår i: Systems Perspectives on Renewable Power 2014. - 9789198097405 ; , s. 32-45
-
Bokkapitel (övrigt vetenskapligt/konstnärligt)abstract
- In this chapter, the technologies for renewable power production of today andin the near future will be described and explained. Renewable power productionis electric power production without using a fuel that will end some day in thefuture. In this chapter, as in this book, power production based on renewable fuels(biomass) is excluded1.Some of the technologies such as wind or solar has reached industry massproduction in recent years, hydro power has been in operation more than 100years and others like wave or ocean current power have still some development todo before robust power production units are available.
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| 22. |
- Carlson, Ola, 1955, et al.
(författare)
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Integration of Wind Power by DC-Power Systems
- 2005
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- The world climate changing is driving the electric power production towards renewable energy sources. The development of wind turbines has reached the power level of 5 MW and wind farms up to 1000 MW are planned. Investigations have shown that the cost for production of wind energy is in the same level as coal and gas. The large amount of hydro power in the Nordic countries can be used tocompensate for the irregularity of producing wind power in Europe. High voltage direct current connections between Sweden and Germany, with a wind farm between can be a solution in the future.
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| 23. |
- Carlson, Ola, 1955, et al.
(författare)
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Power System Voltage Stability Related to Wind Power Generation
- 2006
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Ingår i: 2006 European Wind Energy Conference and Exhibition, Athens, Greece.
-
Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- As is well known the amount of installed wind power increases every day. In the past single wind turbines were installed separately, today wind turbines often are connected to the grid as a group of many turbines, i.e. wind parks. Grid integration considerations have moved from flicker phenomena in the low voltage grid to voltage stability analyses in the transmission grid. This paper starts with an overview of the voltage stability phenomena in a transmission system. Suitable models of wind power generation for power system stability studies - both long and short-term stability - are presented. Different levels of detail of the wind generation models are investigated carefully considering the type of stability study, result accuracy and simulation efficiency. Important aspects such as protection, fault ride-through capability and the capability of producing reactive power are taken into account. The models are then validated against measurements.Three types of wind turbines are considered in this study; fixed speed with induction generator, variable speed operation with doubly fed induction generator and variable speed turbine with full power converter.The main phenomenon that determines the behaviour of a system where fixed speed wind turbines are connected is the large reactive power consumed by the induction machines immediately after the fault has been cleared. This mechanism leads to a voltage stability problem with a risk of voltage collapse as a final consequence. Investigations in short and long term voltage stability have examined the factors affecting the stability limit such as: generated power, fault types, fault duration, fault clearing time, fault voltage and remaining voltage. Variable speed wind turbines with power electronic converter are capable of producing active power at unity power factor. Possibility lies to control reactive power during grid disturbance with the help of an over-rated grid side converter. In this paper the long- and short-term voltage stability aspects of variable speed wind turbines with power electronic converters are illustrated by case studies. Large scale wind power integration at the transmission level has the possibility to improve long term voltage stability of the grid by injecting reactive power. The possibility to produce reactive power increases with a decreased active power production. As well small scale integration at the distribution level can increase short-term voltage stability of the local grid by utilizing its fast reactive power control capability.Finally, several issues related to the modelling and the compatibility of wind power generation in typical power system simulation tools is discussed.
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| 24. |
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| 25. |
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| 26. |
- Carlson, Ola, 1955, et al.
(författare)
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Wind Turbines on Ships
- 2015
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- The start-up company PROPit AB together with Division of Electric Power Engineering has developed a concept for harnessing sea winds for simultaneous electricity generation and thrust, by using conventional, but modified wind turbines onboard merchant vessels. The primary market should be tankers and bulk ships with large and open deck space, operating on routes and in areas with favourable wind conditions. The business idea is to create substantial fuel savings while simultaneously reducing harmful greenhouse gas emissions.
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| 27. |
- Cutululis, Nicolaos Antonio, et al.
(författare)
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Challenges Towards the Deployment of Offshore Grids: the OffshoreDC Project
- 2014
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Ingår i: 13th International Workshop on Large-Scale Integration of Wind Power into Power Systems as well as on Transmission Networks for Offshore Wind Plants, Berlin, Germany, 11-13 Nov. 2014. - 9783981387094
-
Konferensbidrag (refereegranskat)abstract
- This paper summarizes challenges towards the deployment of offshore grids which are dealt with in the Nordic OffshoreDC project. The OffshoreDC project studies the techno-economic challenges related to assessment of the value and use of optimization in the design of offshore grids. The project also studies the technical challenges related to control, protection and provision of ancillary services from HVDC grids with connected wind power plants. Finally, the transients in the DC grids are studied in the project.
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| 28. |
- Ellsen, Magnus, 1961, et al.
(författare)
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Drift, utveckling och dokumentation vid Chalmers provstation för vindenergiforskning
- 2009
-
Rapport (övrigt vetenskapligt/konstnärligt)abstract
- The objective of the project is to carry out research, maintain and run the Wind Turbine at the Hönö test station. Another objective of the project is to make documentation and measurements available on the web. The station is used in research projects as well as a demonstration and a lab facility. The turbine is equipped with a permanent magnet direct driven generator and an electrical system with a DC link suited for variable speed operation. Research is focused mainly on the generator and its electrical system. In this study the generator electrical system has been rebuilt for series compensation. An investigation of series compensation of the PM generator has been made in an earlier study. (”Drift av Hönö provstation – HÖNÖ”, Chalmers, December 2006) That earlier study showed that the use of capacitors in series with the generator windings in comparison to parallel capacitors could increase the power output from the generator by 60%. Measurements made on the rebuilt electrical system confirm this. Several study visits and an Open House are arranged annually. The test station is financed by Göteborg Energi. The report is made within the project ”Drift, utveckling och dokumentation vid Chalmers provstation för vindenergiforskning”.
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| 29. |
- Ellsen, Magnus, 1961, et al.
(författare)
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Series and Parallel Compensation for the Permanent Magnet Synchronous Generator at Chalmers Test Wind Turbine
- 2006
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Ingår i: NORDIC WIND POWER ONFERENCE, 22-23 MAY 2006, ESPOO, FINLAND. ; , s. 10-
-
Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- The objective of the work at Chalmers test station is to carry out research, maintain and run the wind turbine at the plant. The station is used for research projects and as a demonstration and lab facility. The turbine is equipped with a permanent magnet direct-driven generator and an electrical system with a DC link suited for variable speed operation. Research focuses mainly on the generator and its electrical system. Series compensation of the PM generator is investigated. Theoretical studies show that the use of capacitors in series with generator windings in comparison to the present parallel capacitors can increase power output from the generator at a certain design speed interval. Both theoretical calculations and practical tests show that an increase in power by 60 % is possible.
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| 30. |
- Ellsen, Magnus, 1961, et al.
(författare)
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Teknisk slutrapport i projektet Drift av Hönö provstation - HÖNÖ
- 2006
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- The objective of the project is to carry out research, maintain and run the Wind Turbine at the Hönö test station. The station is used in research projects as well as a demonstration and a lab facility. The turbine is equipped with a permanent magnet direct driven generator and an electrical system with a DC link suited for variable speed operation. Research is focused mainly on the generator and its electrical system. An investigation of series compensation of the PM generator has been made. Theoretical studies have shown that the use of capacitors in series with the generator windings in comparison to the present parallel capacitors could increase the power output from the generator. Both theoretical calculations and practical tests show that an increase of the power by 60 % is possible. Several study visits and an Open House are arranged annually. The test station is financed by the Swedish Energy Board and Göteborg Energi. The report is made within the project 'Drift av Hönö provstation - HÖNÖ'. The report describes research and other activities at the test station from the project start 1 July, 2002 until the project end in 30 July, 2005.
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| 31. |
- Espinoza, Nicolas, 1984, et al.
(författare)
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Field-test of wind turbine by voltage source converter
- 2019
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Ingår i: Wind Energy Science. - : Copernicus GmbH. - 2366-7451 .- 2366-7443. ; 4:3, s. 465-477
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Tidskriftsartikel (refereegranskat)abstract
- One of the main challenges for wind energy development is making wind turbines efficient in terms of costs whilst maintaining safe and reliable operation. An important design criterion is to fulfil the grid codes given by the transmission system operators. Grid codes state how wind farms must perform when connected to the grid under normal and abnormal conditions. In this regard, it is well-known that not all technical requirements can be tested by using actual impedance-based test equipment. Therefore, test equipment comprising a fully rated voltage source converter in back-to-back configuration is proposed. Thanks to the full controllability of the applied voltage in terms of magnitude, phase and frequency, the use of voltage-source-converter-based test equipment provides more flexibility compared to actual test systems. As demonstrated in this paper, the investigated test device not only can recreate any type of fault, including its recovery ramp, but also can carry out steady-state tests, such as frequency variations and frequency scan, on the test object. Finally, test results from a 4.1 MW wind turbine and 8 MW test equipment located in Gothenburg, Sweden, are shown to validate the investigated grid code test methodology.
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| 32. |
- Espinoza, Nicolas, 1984, et al.
(författare)
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Frequency Characterization of Type-IV Wind Turbine Systems
- 2016
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Ingår i: 2016 IEEE Energy Conversion Congress and Exposition (ECCE), Milwaukee, WI, USA, 2016. - 2329-3721. - 9781509007370 ; , s. Article no 7855126-
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Konferensbidrag (refereegranskat)abstract
- The continuous need for renewable energy sources is a driving force for a fast development of wind turbine technologies. It is well known that control interactions can arise if the wind farms and the interconnecting system, for example ac collector system or high voltage direct current (HVDC)-link, are not properly integrated. One tool to assess the stability of the system is to analyse the input impedance of the wind farm together with the connecting grid impedance. In this regard, this paper investigates the impact of different system parameters in the input admittance of the generating unit. The admittance is analysed for a wide range of frequencies. Moreover, the passive and non-passive behavior of the admittance is highlighted and the risk of interaction between the wind turbine and other elements of the grid is discussed.The system under consideration consists of a multi megawatt type-IV wind turbine system and a fully-rated voltage source converter (VSC)-based testing equipment used as verification tool for frequency scanning. First, the mathematical model of the system and the scanning method are presented. The input admittance is calculated for a variety of operating conditions including variations of control settings such as phase-locked loop (PLL) and close-loop current control bandwidth and system parameters, such as the output filter configuration. Finally, the investigated methodology is verified using time-domain simulations and field test results.
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| 33. |
- Espinoza, Nicolas, 1984, et al.
(författare)
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Grid code testing of full power converter based wind turbines using back-to-back voltage source converter system
- 2013
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Ingår i: EWEA Annual Event 2013 conference proceedings. ; 2
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Konferensbidrag (refereegranskat)abstract
- This paper presents an alternative approach of grid code testing for wind turbines (WTs) using back-to-back Voltage Source Converter (VSC). In particular, this paper focuses on grid code analysis for WTs, and low voltage ride through (LVRT) testing for full power converter (FPC) based WTs. Recent European grid codes are analyzed and selected for testing according to their strictness and wind power penetration in each country. The investigated testing setup consists of a 4 MW FPC-based WT and an 8 MW back-to-back VSC system, operated as a test equipment. The effectiveness of the investigated grid code testing method is validated using the simulation tool PSCAD/EMTDC, where the electrical systems of the WT as well as the test equipment are modeled in detail. A control strategy for the WT is given; in addition, hardware and control algorithms for the converter-based test equipment are described, with special focus on their limitations for testing procedures. The results demonstrate the capability of the investigated testing device in producing a controllable voltage dip at the terminals of the WT, at the same time that is being fed with short circuit currents. Moreover, its flexibility in emulating the behavior of the grid in continuous and dynamic condition is highlighted and discussed in extent.
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| 34. |
- Espinoza, Nicolas, 1984, et al.
(författare)
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Novel LVRT Testing Method for Wind Turbines Using Flexible VSC Technology
- 2015
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Ingår i: IEEE Transactions on Sustainable Energy. - : Institute of Electrical and Electronics Engineers (IEEE). - 1949-3029 .- 1949-3037. ; 6:3, s. 1140-1149
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Tidskriftsartikel (refereegranskat)abstract
- Wind energy is one of the fastest growing renewable energy sources. For this reason, several countries have included requirements in their grid codes to guarantee proper operation of wind turbines under stable operations of the power systems as well as under grid disturbances. This paper presents a novel methodology for grid code testing of wind turbines based on voltage source converter (VSC) technology. In particular, this paper focuses on a low voltage ride through (LVRT) test of a full size converter-based wind turbine. The investigated testing setup consists of a 4-MW wind turbine and an 8-MW back-to-back VSC system, operated as test equipment. The control algorithm of the testing device is derived in detail and validated through time-domain simulations. The risk of poorly damped resonances and possible interaction between the testing equipment and the tested object is investigated through small signal analysis. The obtained results demonstrate the flexibility of the proposed approach in controlling the voltage at the wind turbine terminals, including the ability in emulating the short-circuit impedance of the grid at the connection point.
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| 35. |
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| 36. |
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| 37. |
- Haghbin, Saeid, 1977, et al.
(författare)
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A Combined Motor/Drive/Battery Charger Based on a Split-Windings PMSM
- 2011
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Ingår i: 7th IEEE Vehicle Power and Propulsion Conference, VPPC 2011, Chicago, 6-9 September 2011. - 9781612842486
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Konferensbidrag (refereegranskat)abstract
- An integrated motor/drive/battery charger is proposed, designed and simulated for vehicles using grid power to charge the system batteries. The machine stator windings are re-configured by a relay-based switching device for charging to constitute a special grid connected generator. This rotary generator (machine with re-configured windings) provides an isolated three-phase power source for the inverter to make a three-phase boost battery charger. The system design and operation in the charging and traction modes are explained for the proposed integrated motor/drive/battery charger. The charging power is half of the traction power for the proposed system. Simulation results are provided to verify the proper operation for the proposed system.
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| 38. |
- Haghbin, Saeid, 1977, et al.
(författare)
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A trigonometric velocity estimator using a resolver sensor in drive system applications
- 2012
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Ingår i: IECON Proceedings (Industrial Electronics Conference). - 2162-4704 .- 2577-1647. - 9781467324199 ; , s. 2889 - 2894
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Konferensbidrag (refereegranskat)abstract
- Resolver sensors are widely used in the industry to measure the rotor angle position in high performance drive applications. Different methods are employed to estimate the velocity by measuring the rotor angle position. A novel trigonometric velocity estimator is described in this paper that has a simple structure for implementation and there is no need for parameter tuning. The proposed method is practically verified in a permanent magnet motor drive system. The results confirm that the proposed trigonometric velocity estimator has a good dynamic and steady state response subjected to different speed command profiles.
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| 39. |
- Haghbin, Saeid, 1977, et al.
(författare)
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An Integrated 20-kW Motor Drive and Isolated Battery Charger for Plug-In Vehicles
- 2013
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Ingår i: IEEE transactions on power electronics. - 0885-8993 .- 1941-0107. ; 28:8, s. 4013-4029
-
Tidskriftsartikel (refereegranskat)abstract
- For vehicles using grid power to charge the battery, traction circuit components are not normally engaged during the charging time, so there is a possibility to use them in the charger circuit to have an on-board integrated motor drive and battery charger. An isolated high-power three-phase integrated motor drive and charger based on a split-phase permanent magnet motor is presented in this paper. The motor winding connections are reversible by a relay-based switching device for traction and battery charging. In traction mode, the motor is a classical three-phase motor, but in charging mode it is a rotating isolating transformer providing a three-phase voltage source for the inverter to charge the battery. A mathematical model of the motor with six stator windings is presented for an arbitrary phase shift in windings. For the charging mode, the split-phase motor grid synchronization process and charge control are explained including the developed controller. A 20-kW system is designed and implemented to verify the proper operation of the proposed system. Simulation and practical results are provided to show the system performance in terms of functionality, dynamic response, and efficiency. Moreover, some discussions, recommendations, and limitations are provided to give more practical insights.
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| 40. |
- Haghbin, Saeid, 1977, et al.
(författare)
-
An integrated charger for plug-in hybrid electric vehicles based on a special interior permanent magnet motor
- 2010
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Ingår i: Vehicle Power and Propulsion Conference (VPPC) Proceedings, Sep. 2010, Lille, France. - 9781424482191
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Konferensbidrag (refereegranskat)abstract
- For a plug-in hybrid electric vehicle (PHEV), the battery needs to be charged from the grid while the vehicle is parked. The traction system components are normally not engaged during the charging time so there is a possibility to use them in the charger system to develop an integrated charger. An innovative high power isolated three-phase bi-directional integrated charger with unit power factor operation is introduced for PHEVs based on a special configuration of the ac motor. The winding of the machine is re-arranged in charging mode to have a three-phase boost based high power battery charger. The system configuration, the device model (machine with multiple windings), traction and charging system functionality and charger control are presented in this paper.
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| 41. |
- Haghbin, Saeid, 1977, et al.
(författare)
-
An integrated split-phase dual-inverter permanent magnet motor drive and battery charger for grid-connected electric or hybrid vehicles
- 2012
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Ingår i: 2012 20th International Conference on Electrical Machines, ICEM 2012, Marseille, 2 - 5 September 2012. - 9781467301428 ; , s. 1941-1947
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Konferensbidrag (refereegranskat)abstract
- Multi-phase machines have some features such as reduced power electronic components rating, reduced torque ripple, and increased reliability that make them a favorable option in some applications, for instance in the area of highpower drive systems. A combined motor drive and battery charger based on a split-phase interior permanent magnet synchronous motor and dual inverters is proposed and explained in this paper. By connecting the two motor winding star points to a single-phase ac supply, it is possible to charge the battery through the inverters from a commonly available single-phase outlet. In this way, a separate battery charger is not needed. A double dq model of the motor is presented and based upon a maximum torque per ampere control strategy is used for the traction mode. To eliminate the look up table to obtain the reference value of the current q component from the torque error, a linearized version of the controller is used that is explained. The system operation in the charging mode including the equivalent circuit and inverter control is also explained. Moreover, simulation results are provided to verify the proper operation of the proposed system.
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| 42. |
- Haghbin, Saeid, 1977, et al.
(författare)
-
An Isolated High-Power Integrated Charger in Electrified-Vehicle Applications
- 2011
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Ingår i: IEEE Transactions on Vehicular Technology. - 1939-9359 .- 0018-9545. ; 60:9, s. 4115-4126
-
Tidskriftsartikel (refereegranskat)abstract
- For electric and hybrid vehicles that use grid power to charge the battery, traction circuit components are not normally engaged during the charging time; hence, there is a possibility of using the traction circuit components in the charger circuit to have an onboard integrated charger. An isolated high-power integrated charger based on a special electrical machine with a double set of stator windings is described. Through the reconfiguration of the motor stator windings in the charging mode, a six-terminal machine is achieved. The so-called motor/generator acts as an isolated three-phase power source after synchronization with the utility grid in the charging mode. This rotary isolated power source constitutes a three-phase boost rectifier (battery charger) with full utilization of the inverter. The motor windings are reconfigured by a relay-based switching device for the charging and traction modes. This paper presents the mathematical model of the motor/generator and explains the system's functionality for the traction and charging modes. Furthermore, the charger grid synchronization and charge control are described. Finally, the simulation results are presented for a practically designed system with a traction power of 25 kW and a possible charge power of 12.5 kW.
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| 43. |
- Haghbin, Saeid, 1977, et al.
(författare)
-
Grid-Connected Integrated Battery Chargers in Vehicle Applications: Review and New Solution
- 2013
-
Ingår i: IEEE Transactions on Industrial Electronics. - 0278-0046 .- 1557-9948. ; 60:2, s. 459-473
-
Tidskriftsartikel (refereegranskat)abstract
- For vehicles using grid power to charge the battery, traction circuit components are not engaged during the charging time, so there is a possibility to use them in the charger circuit to have an onboard integrated charger. The battery charger can be galvanically isolated or nonisolated from the grid. Different examples of isolated or nonisolated integrated chargers are reviewed and explained. Moreover, a novel isolated-high-power three-phase battery charger based on a split-phase permanent-magnet motor and its winding configuration is presented in this paper. The proposed charger is a bidirectional high-power charger with a unity power factor operation capability that has high efficiency.
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| 44. |
- Haghbin, Saeid, 1977, et al.
(författare)
-
Integrated chargers for EV's and PHEV's: examples and new solutions
- 2010
-
Ingår i: XIX IEEE International Conference on Electrical Machines (ICEM), Rome, Italy, 2010. - 9781424441747
-
Konferensbidrag (refereegranskat)abstract
- The battery is an important component in an electric vehicle (EV) or a plug-in hybrid electric vehicle (PHEV) and it should be charged from the grid in a cost efficient, preferably fast and definitely safe way. The charger could be an on board or an off board charger. For an on board charger it is possible to use available hardware of the traction system, mainly the inverter and the electric motor, in the charger circuit. This is called an integrated charger. In this paper, different examples of integrated chargers are reviewed and explained. Additionally, other possible solutions of integrated chargers are described.
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| 45. |
- Haghbin, Saeid, 1977, et al.
(författare)
-
Integrated Motor Drive and Non-Isolated Battery Charger Based on the Split-Phase PM Motors for Plug-in Vehicles
- 2014
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Ingår i: The Journal of Engineering. - 2051-3305.
-
Tidskriftsartikel (refereegranskat)abstract
- A novel integrated motor drive and non-isolated battery charger based on a split-phase permanent magnet (PM) motor is presented and described for a plug-in vehicle. The motor windings are reconfigured by a relay for the traction and charging operation. In traction mode, the motor is like a normal three-phase motor, whereas in the charging mode, after windings reconnection, the system is a three-phase Boost rectifier. One important challenge to use the motor as three inductors in charger circuit is to have it in standstill during the battery charging. Based on the presented mathematical model of a split-phase PM motor, the zero-torque condition of the motor is explained which led to a proper windings reconnection for the charging. Simulation and experimental results of two separate practical systems are provided to verify the proposed integrated battery charger. Some practical limitations and design recommendations are provided to achieve a more realistic practical system.
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| 46. |
- Haghbin, Saeid, 1977, et al.
(författare)
-
Modal Field-Oriented Control of a Split-Phase PM Motor with Dual Inverters
- 2013
-
Ingår i: Journal of Electrical and Control Engineering. - 2226-2881. ; 3, s. 7-16
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Tidskriftsartikel (refereegranskat)abstract
- Multiphase machines have a higher efficiency, greater fault tolerance, lower torque ripple and reduced rated power electronics rating compared to their three-phase counterparts. However, the drive system and control is more complicated for the multiphase machines. A novel drive system for a split-phase permanent magnet motor and dual inverters is presented and explained in this paper. Field-oriented control (FOC) is utilized for the speed controlwhich a new decoupled current controllers are exploited to remove the tight coupling between the d and q current components. An eigenvalue decomposition method is used to transform the system state-space equations to its modal form. Based upon, the decoupled PI current controllers are proposed including the design procedure. A maximum torque per ampere (MTPA) strategy is developed to determine the reference values for the current controllers. Simulation results are provided to show that the proposed drive system has a good dynamic and steady state performance in a speed control system.
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| 47. |
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| 48. |
- Hagmar, Hannes, 1990, et al.
(författare)
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A Survey of Voltage Stability Indicators Based on Local Synchronized Phasor Measurements
- 2018
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Ingår i: 2018 North American Power Symposium (NAPS).
-
Konferensbidrag (refereegranskat)abstract
- This paper reviews and evaluates the main types of voltage stability indicators (VSIs) based on local measurements and further provides a background to their development. Due to weaknesses during dynamic conditions, the bus VSIs based on Thévenin’s equivalent impedance methods are in general found to be unsuitable for most corrective applications, but may instead be used to estimate local loadability margin to voltage instability. Line VSIs, although requiring some data communication, are in general found to be more robust and may in most cases be used both for predictive and corrective applications. Sensitivitybased VSIs are typically more accurate for detecting voltage instability, but are instead sensitive to measurement noise and are highly nonlinear when the system is close to a voltage collapse, consequently being unsuitable for estimating stability margins. The VSIs based on the local identification of voltage emergency situations (LIVES) concept can take into account the delayed effects from load tap changers, making them suitable for corrective applications and to use in local protection schemes.
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| 49. |
- Hagmar, Hannes, 1990, et al.
(författare)
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Integration Aspects of Full Converter Wind Turbines and the Impact on Long-term Voltage Stability
- 2019
-
Ingår i: IEEE Power and Energy Society General Meeting. - 1944-9925 .- 1944-9933. ; 2019-August
-
Konferensbidrag (refereegranskat)abstract
- This paper examines how various integration aspects of full converter wind turbines, such as grid code design, control aspects, and placement of turbines, impact the long-term voltage stability of a power system. The simulations are conducted on a modified version of the Nordic32 test system. Different cases have been analyzed and show, for example, that if over-dimensioning of converters is implemented, it is mainly the converters’ current capacity that should be increased since the voltage limitation of converters seldom is reached during voltage instability events. Furthermore, a restrictive reactive control scheme is tested, with the aim of minimizing the wear and maintenance of converter components. Although found to generally reduce the voltage stability, the proposed control scheme could be adopted during specific conditions where the local need of voltage support is low. The placement of larger wind farms was found to have the largest impact, both on long-term voltage stability of the system itself, and on the effect that the analyzed design and control aspects had on the system stability. Consequently, the placement of WFs is found be an important factor to consider when designing ancillary services and grid codes for wind power.
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| 50. |
- Hagmar, Hannes, 1990, et al.
(författare)
-
On-line Voltage Instability Prediction using an Artificial Neural Network
- 2019
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Ingår i: 2019 IEEE Milan PowerTech, PowerTech 2019.
-
Konferensbidrag (refereegranskat)abstract
- In this paper, a predictive method to detect voltage instability using an artificial neural network is presented. The proposed method allows transmission system operators to predict long-term voltage instability far before the system voltage stability has been degraded, allowing swift and cost-effective control actions. The predictor is tested and trained on the Nordic32 test system for a wide range of different contingencies. The predictor proves to be accurate in providing early warnings of impending voltage instability, allowing 96.3 % of all test cases being correctly classified only seconds after a contingency. The method is proposed to be used as an effective tool for supplementary voltage instability detection for transmission system operators.
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