| 1. |
- Mai, Tam T., et al.
(författare)
-
An overview of grid-edge control with the digital transformation
- 2021
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Ingår i: Electrical Engineering. - : Springer Science and Business Media LLC. - 1432-0487 .- 0948-7921. ; 103:4, s. 1989-2007
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Tidskriftsartikel (refereegranskat)abstract
- Distribution networks are evolving to become more responsive with increasing integration of distributed energy resources (DERs) and digital transformation at the grid edges. This evolution imposes many challenges to the operation of the network, which then calls for new control and operation paradigms. Among others, a so-called grid-edge control is emerging to harmonise the coexistence of the grid control system and DER’s autonomous control. This paper provides a comprehensive overview of the grid-edge control with various control architectures, layers, and strategies. The challenges and opportunities for such an approach at the grid edge with the integration of DERs and digital transformation are summarised. The potential solutions to support the network operation by using the inherent controllability of DER and the availability of the digital transformation at the grid edges are discussed.
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| 2. |
- Nguyen, Anh, et al.
(författare)
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Wind Power in Power Markets: Opportunities and Challenges
- 2007
-
Ingår i: Nordic Wind Power Conference, 1-2 November 2007, Roskilde, Denmark.
-
Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- This paper provides a comprehensive review of the opportunities and challenges from trading of wind power in power markets. The opportunities are the low operating costs, government incentive/subsidy program, reduction of market price, reduction of carbon dioxide emission, reduction of network loss, etc. The challenges would be technical requirement for power system integration, high investment cost, increased requirement on regulation power due to wind forecast error, more price volatile, more market competition for other generations, etc. The opportunities and challenges are discussed from different market players’ perspectives. Some suggestions for possible measures to overcome those challenges are presented.
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| 3. |
- Srivastava, Ankur, 1989, et al.
(författare)
-
Development of a DSO Support Tool for Congestion Forecast
- 2021
-
Ingår i: IET Generation, Transmission and Distribution. - : Institution of Engineering and Technology (IET). - 1751-8687 .- 1751-8695. ; 15:23, s. 3345-3359
-
Tidskriftsartikel (refereegranskat)abstract
- This paper presents a novel DSO support tool with visualisation capability for forecasting network congestion in distribution systems with a high level of renewables. To incorporate the uncertainties in the distribution systems, the probabilistic power flow framework has been utilised. An advanced photovoltaic production forecast based on sky images and a load forecast using an artificial neural network is used as the input to the tool. In addition, advanced load models and operating modes of photovoltaic inverters have been incorporated into the tool. The tool has been applied in case studies to perform congestion forecasts for two real distribution systems to validate its usability and scalability. The results from case studies demonstrated that the tool performs satisfactorily for both small and large networks and is able to visualise the cumulative probabilities of nodes voltage deviation and network components (branches and transformers) congestion for a variety of forecast horizons as desired by the DSO. The results have also shown that explicit inclusion of load-voltage dependency models would improve the accuracy of the congestion forecast. For demonstrating the applicability of the tool, it has been integrated into an existing distribution management system via the IoT platform of a DMS vendor, Atos Worldgrid.
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| 4. |
- Wang, Feng, 1975, et al.
(författare)
-
An extended OPF incorporating multi-terminal VSC-HVDC and its application on transmission loss evaluation
- 2013
-
Ingår i: 2013 IEEE Grenoble Conference PowerTech, POWERTECH 2013. - 9781467356695
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Konferensbidrag (refereegranskat)abstract
- This paper proposes an extension of the traditional ac Optimal Power Flow (OPF) model to incorporate the Voltage Source Converter based Multi-terminal High Voltage Direct Current system (VSC-MTDC). In the extended OPF model, the detailed VSC-MTDC system model is included, and the key technical limits of VSC (e.g., the maximum VSC valve current and the maximum dc voltage) are used as the operating constraints of the VSC-MTDC system. The extended OPF model is applied to a case study using the Nordic 32-bus system to evaluate the contribution of the embedded VSC-MTDC system on the overall system loss reduction. The study results show that the overall system loss of an ac transmission grid is not necessarily reduced by embedding a VSC-MTDC system into it. The reduction of the system loss by embedded VSC-MTDC system depends on their configuration and location, and the VSC station loss ratio as well.
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| 5. |
- Agathokleous, Christos, 1993, et al.
(författare)
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Stochastic Operation Scheduling Model for a Swedish Prosumer with PV and BESS in Nordic Day-Ahead Electricity Market
- 2019
-
Ingår i: 2019 IEEE Milan PowerTech, PowerTech 2019.
-
Konferensbidrag (refereegranskat)abstract
- In this paper, an optimal stochastic operation scheduling model is proposed for a prosumer owning photovoltaic (PV) facility coupled with a Battery Energy Storage System (BESS). The objective of the model is to maximize the prosumer’s expected profits. A two-stage stochastic mixed-integer nonlinear optimization (SMINLP) approach is used to cope with the parameters’ uncertainties. Artificial Neural Networks (ANN) are used to forecast the markets’ prices and the standard scenario reduction algorithms are applied to handle the computational tractability of the problem. The model is applied to a case study using data from the Nordic electricity markets and historical PV production data from the Chalmers University of Technology campus, considering a scaled up 5MWp power capacity. The results show that the proposed approach could increase the revenue for the prosumer by up to 11.6% as compared to the case without any strategy. Furthermore, the sensitivity analysis of BESS’s size on the expected profit shows that increasing BESS size could lead to an increase in the net profits.
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| 6. |
- Alghamdi, Baheej, et al.
(författare)
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A Comparative Study on SVC and STATCOM in Dynamic Voltage Stability Improvement of a System with Different Load Characteristics
- 2017
-
Ingår i: 2017 SAUDI ARABIA SMART GRID CONFERENCE (SASG). - 9781538618769
-
Konferensbidrag (refereegranskat)abstract
- This paper presents a comparison between the dynamic performance of Static Var Compensators (SVC) and Static Synchronous Compensators (STATCOM) in improving the voltage stability of the system and reducing the post disturbance voltage recovery time. The dynamic simulation has been done on the Nordic-32 test system which mimics the characteristics of the Swedish transmission system. The simulation has been carried out using a time-domain simulation software called PSS/E. The simulation has been done while taking into account different load characteristics including induction motor loads which are prevalent in the Swedish power grid. A methodology for sizing and placement of the SVC and STATCOM has been proposed to mitigate the voltage instability of the system. It has been found that STATCOMs have shown superior performance over SVCs in improving the post-disturbance voltage recovery time and the voltage stability of the system. It has been found that the post disturbance voltage recovery time was reduced down by 60% for the case with STATCOM while for the case with SVC, the voltage recovery time was reduced down by 26% for the same capacitive rating as that of the STATCOM(1).
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| 7. |
- Alghamdi, Baheej, et al.
(författare)
-
A comparative study on SVC and STATOCM in dynamic voltage stability improvement of a system with different load characteristics
- 2018
-
Ingår i: 2017 Saudi Arabia Smart Grid Conference, SASG 2017. ; , s. 1-5
-
Konferensbidrag (refereegranskat)abstract
- This paper presents a comparison between the dynamic performance of Static Var Compensators (SVC) and Static Synchronous Compensators (STATCOM) in improving the voltage stability of the system and reducing the post disturbance voltage recovery time. The dynamic simulation has been done on the Nordic-32 test system which mimics the characteristics of the Swedish transmission system. The simulation has been carried out using a time-domain simulation software called PSS/E. The simulation has been done while taking into account different load characteristics including induction motor loads which are prevalent in the Swedish power grid. A methodology for sizing and placement of the SVC and STATCOM has been proposed to mitigate the voltage instability of the system. It has been found that STATCOMs have shown superior performance over SVCs in improving the post-disturbance voltage recovery time and the voltage stability of the system. It has been found that the post-disturbance voltage recovery time was reduced down by 60% for the case with STATCOM while for the case with SVC, the voltage recovery time was reduced down by 26% for the same capacitive rating as that of the STATCOM1.
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| 8. |
- Alghamdi, Baheej, 1985, et al.
(författare)
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Investigation of Impacts of Solar PV on Transmission System Voltage Stability Considering Load Characteristics and Protection
- 2017
-
Ingår i: 7th International Workshop on the Integration of Solar Power into Power Systems, 24-25 October 2017, Berlin, Germany.
-
Konferensbidrag (refereegranskat)abstract
- This paper presents an investigation on possible effects of large scale integration of solar photovoltaics (PVs) on the voltage stability of the transmission grid. The time-domain simulation approach has been used in a case study using the Nordic-32 test system which approximately represents the Swedish transmission system. The simulation study has been carried out in PSS/E for different penetration levels of solar PVs and solar irradiance conditions considering different load characteristics and detailed model of distance relays. The main question to be addressed by the study is how the location and size of the PV plants, load characteristics and the transmission system distance protection can adversely affect the post-disturbance voltage recovery time and thereby the overall voltage stability. It has been found that the post-disturbance voltage recovery time increased by 100% with 30% PV penetration. Another interesting finding is that in the case of high PV penetration, the PV plants can either support or adversely affect the voltage stability of the system, depending on changes in the irradiance and the load level during the day. That is that during periods when the PV plants produce their rated active power, the system was more prone to voltage instability after being subjected to a disturbance compared to the periods where the PV plants produce only reactive power which supports the voltage stability.
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| 9. |
- Alvarez Quispe, Erik Fransisco, et al.
(författare)
-
Values and Impacts of Incorporating Local Flexibility Services in Transmission Expansion Planning
- 2022
-
Ingår i: Electric Power Systems Research. - : Elsevier BV. - 0378-7796. ; 212
-
Tidskriftsartikel (refereegranskat)abstract
- This paper presents a cost-based TSO-DSO coordination model to quantify the value of local flexibility services and analyze its impact on the transmission grid expansion and the system operation. Flexibility is provided to the DC power flow transmission grid model by microgrids within the integrated AC power flow distribution grid model. The model's objective is to minimize the overall cost of transmission investments and procured flexibility and is achieved using a bilevel optimization approach where the power exchanges on all connected grid interfaces are controlled. Case studies using a combined test system of the IEEE RTS-96 transmission network interfacing multiple 33-bus distribution grids were performed to validate the model and assess the values and impacts of local flexibility on the transmission system expansion. The results showed that the proposed model modified the investment plan and dispatch of flexibility resources reducing the investment and operation cost of the transmission system.
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| 10. |
- Antoniadou-Plytaria, Kyriaki, 1989, et al.
(författare)
-
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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| 11. |
- Antoniadou-Plytaria, Kyriaki, 1989, et al.
(författare)
-
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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| 12. |
- 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
-
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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| 13. |
- Antoniadou-Plytaria, Kyriaki, 1989, et al.
(författare)
-
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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| 14. |
- Antoniadou-Plytaria, Kyriaki, 1989, et al.
(författare)
-
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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| 15. |
- Antonis, Papaemmanouil, et al.
(författare)
-
A cost-benefit analysis of transmission network reinforcement driven by generation capacity expansion
- 2010
-
Ingår i: IEEE Power & Energy Society (PES) General Meeting 2010, Minneapolis, USA, July 25 - 29, 2010. - 9781424483570
-
Konferensbidrag (refereegranskat)abstract
- This paper assesses the effects of the future European power generation system with strict CO2 emission reduction targets on the planning of cross-border interconnection lines. Results from a techno-economic energy systems model have been used as input to this work, regarding the development of the European power generation system until the year 2050, meeting the EU 2020 CO2 target and a 85% emissions reduction until the year 2050. A simplified UCTE power system model was developed in order to analyze how the cross-border interconnections in continental Europe are affected by the generation plans using an iterative method. The paper also attempts to identify the congestion points and proposes solutions based on nodal price modeling. A cost-benefit analysis (CBA) is used to evaluate the appropriate transmission planning strategy, with the costs being the long-term investment costs and the benefits being both the avoided environmental costs and the total congestion costs. The effects of new investments on the nodal prices are also studied. The results show that the profitability of the investments is influenced by the available production mix and the forecasted CO2 prices. The avoided congestion costs participate rather insignificantly in the CBA, which means that congestions are not relieved, showing that many interconnections are insufficient for nodal pricing market structure.
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| 16. |
- Antonis, Papaemmanouil, et al.
(författare)
-
Improved Cost-Benefit Analysis for Market-Based Transmission Planning, A European Perspective
- 2013
-
Ingår i: Energy Policy. - : Elsevier BV. - 0301-4215. ; 63, s. 215-223
-
Tidskriftsartikel (refereegranskat)abstract
- This paper addresses the problem of transmission planning in interconnected power systems under the uncertainty of future generation parks and fast varying marginal production costs. The decision maker has to consider many different aspects during the denition of dierent transmission planning strategies, that sometimes might even be contradicting. Major contributions are the incorporation of energy policy measurements in the evaluation process of candidate transmission plans and the inclusion of short and long-term uncertainties. The proposed methodology, so called C-TRAP, is based on a semi-dynamic heuristic approach, that solves the social welfare maximization problem for several discrete steps considering different preferences for energy policy and transmission network reinforcements. The flexibility provided through the heuristic analysis is very important for decision makers in the new uncertain environment in power systems.
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| 17. |
- Antonis, Papaemmanouil, et al.
(författare)
-
Improved cost-benefit analysis for reliable long-term transmission planning
- 2011
-
Ingår i: 2011 IEEE PES Trondheim PowerTech: The Power of Technology for a Sustainable Society, POWERTECH 2011; Trondheim; 19 June 2011 through 23 June 2011. - 9781424484195
-
Konferensbidrag (refereegranskat)abstract
- The aim of this paper is to incorporate reliabilityaspects in the transmission planning process presentedin previous work. The decision maker has to consider manydifferent aspects during the definition of transmission planning strategy, that sometimes might be contradicting. In the whole planning framework the decision is made by combining economic, environmental, and security of supply criteria in a single pseudodynamic algorithm. However, here only the part of security of supply is analyzed. After a sensitivity analysis for identification of critical/important transmission lines, a contingency analysis is performed and the probability of expected unserved energy is calculated together with the costs of expected unserved energy as an indicator. It is also shown that the amount of expected unserved energy is decreasing when additional transmission capacity is added to the connected lines of an unbalanced node. However, this may not be enough to reach zero unserved energy due to limitations of other transmission lines. After all,transmission network reinforcements can be evaluated based on benefits in avoided environmental costs, avoided congestion costs and avoided unserved energy costs in order to provide sufficient information to the decision maker.
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| 18. |
- Arafat, Yasir, 1985, et al.
(författare)
-
Customer-Utility Interface for 2030 - Identification of functionalities and applications
- 2015
-
Rapport (övrigt vetenskapligt/konstnärligt)abstract
- Smart metering is considered to become a central part in distribution grid management in the future and will be able to provide a lot of new functions if they have the right specifications. Many DSOs are in the process of preparing for the next generation of Smart Meters (SMs) – which is referred to as the future customer-utility interface (CUI) and thereby needs to know the required specifications. This report is proposed to assist in this process by providing suggestions of research to establish minimum technical CUI specifications with regards to the different possible functionalities of CUI. To investigate the requirement of new functionalities, the report addresses how both the distribution system operator (DSOs) and customers could benefit from the new functionalities and what challenges the functionalities can meet. The project focused specifications for increasing the efficiency of grid management. Moreover, the report discuss functionalities required to enable customers’ participation in Demand Response (DR). The report is based on a literature review on functionalities requirement for the future CUI which satisfy the general requirement by the European Commission (EC) and Swedish Energy Market Inspectorate (EI) and at the same time will enhance the operation and planning practices of the DSOs, and promote more active customers. Based on how the grid may look like in 2030 in terms of electric power generations, loads and equipment of the grid and the expected changes in electricity demand but also other demands from the rest of the society is research issues selected and discussed. In the end the challenges are ranked and the risk of congesting due to higher covariant between loads and due to customer’s participation in different types of markets may be the most challenging is considered the most challenges in the nearby future for the distribution grid. There is therefore an urgent need to developing methods for more load forecasting and market modelling to understand where in the grid problem will appear before they actually happen. There are different methods on how to meet the congestions but more load modelling is needed to explore the potential of changes between different operation strategies. Finally there is also a need to develop a method to be able to compare the different method to find the most cost efficient way to solve each problem.
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| 19. |
- Babaei, Saman, et al.
(författare)
-
Effects of PHEVs in power distribution systems: reviews and analyses
- 2010
-
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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| 20. |
- Babaei, Saman, et al.
(författare)
-
Effects of Plug-in Electric Vehicles on Distribution Systems: The Real Case of Gothenburg
- 2010
-
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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| 21. |
- Bachiller, Raul, et al.
(författare)
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Optimal Market Settlements Incorporating Voltage Stability
- 2008
-
Ingår i: 2008 IEEE International Conference on Sustainable Energy Technologies, ICSET 2008; Singapore; Singapore; 24 November 2008 through 27 November 2008. - 9781424418886 ; , s. 1145-1150
-
Konferensbidrag (refereegranskat)abstract
- This study aims at investigating the changes in power market transaction levels when taking into account the voltage stability consideration in the market settlement scheme. The study is based on a security constrained optimal power flow (SC-OPF) framework for a combined bilateral-and-pool electricity market. An IEEE 30-bus test system is used in the study. It is found that the voltage security constraints could help independent market operators to include a sufficient margin for allowable power transactions to ensure the system security while maximizing the social welfare. In that case, the power systems will be operating with a larger security margin. It is, however, important to note that the social welfare is compromised with the increased security margin.
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| 22. |
- Balram, Pavan, 1986, et al.
(författare)
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Centralized charging control of plug-in electric vehicles and effects on day-ahead electricity market price
- 2015
-
Ingår i: Plug In Electric Vehicles in Smart Grids. - Singapore : Springer. - 9789812873163 - 9789812873170 ; 88, s. 267-299
-
Bokkapitel (refereegranskat)abstract
- Global policy targets to reduce greenhouse gas emissions have led to increased interest in plug-in electric vehicles (PEV) and their integration into the electricity network. Existing electricity markets, however, are not well suited to encourage direct participation of flexible demand from small consumers such as PEV owners. The introduction of an aggregator agent with the functions of gathering, aggregating, controlling and representing the energy needs of PEV owners in the electricity market could prove useful in this regard. In this chapter, a mathematical model of PEV aggregator for participation in the day-ahead electricity market is described. The modeling is done by treating each of the individual vehicle batteries as a single large battery. The centralized charging and discharging of this battery is then scheduled based on the traveling needs of the PEV owners determined by an aggregated driving profile and the cumulative electrical energy needs of vehicles over the optimization horizon. Two methods for scheduling PEV demand named as joint scheduling method (JSM) and aggregator scheduling method (ASM) are presented. The two methods are subsequently used to observe the effects of introducing flexible scheduling of PEVs on the day-ahead market price in an IEEE test system and a Nordic test system. Results from the IEEE test system case studies will indicate that the scheduling of PEV energy through direct centralized control at high PEV penetration levels of 50 % or greater could lead to potential lowering of day-ahead market prices as compared to an indirect control method such as the use of fixed period charging. Results from the Nordic test system case study shows that controlled scheduling of PEV demand could lead to only a small increase in day-ahead market price of electricity.
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| 23. |
- Balram, Pavan, 1986, et al.
(författare)
-
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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| 24. |
- Balram, Pavan, 1986, et al.
(författare)
-
Demonstration of Voltage Control in a Real Distribution System using Model Predictive Control
- 2017
-
Ingår i: IET Generation, Transmission and Distribution. - : Institution of Engineering and Technology (IET). - 1751-8687 .- 1751-8695. ; 11:16, s. 3922-3929
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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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| 25. |
- Balram, Pavan, 1986, et al.
(författare)
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Effects of Plug-in Electric Vehicle Charge Scheduling on the Day-ahead Electricity Market Price
- 2012
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Ingår i: IEEE PES Innovative Smart Grid Technologies 2012. - 2165-4816. - 9781467325950 ; , s. 8-
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Konferensbidrag (refereegranskat)abstract
- With the advent of plug-in electric vehicles (EV), it becomes increasingly important to study the impact of charge scheduling of a large number of EVs on the day-ahead electricity market price. In this paper, two scheduling models are proposed- joint scheduling model and aggregator scheduling model. They are used to study the effects of scheduling of EV charging on the day-ahead market price of electricity at various penetration levels of the EVs. Results from studies on an IEEE 30-bus test system show that, at lower penetration of EVs, a simple scheduling method using fixed-period charging during low demand periods can be used, without a large increase in market price. But at higher penetration levels, the opposite holds true, requiring advanced scheduling methods such as proposed in this paper. Between the two, joint scheduling model results in a lower increase in electricity price and is further tested on a simplified Nordic day-ahead market model. An overall conclusion is that the Nordic day-ahead market can accommodate large penetration of EVs without a significant increase in market price.
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