Publications
541 results found
Giannelos S, Konstantelos I, Strbac G, 2015, Option value of Soft Open Points in distribution networks, IEEE Powertech, Publisher: IEEE
We propose a novel stochastic planning model thatconsiders investment in conventional assets as well as in SoftOpen Points, as a means of treating voltage and thermalconstraints caused by the increased penetration of renewabledistributed generation (DG) sources. Soft Open Points areshown to hold significant option value under uncertainty;however, their multiple value streams remain undetected undertraditional deterministic planning approaches, potentiallyundervaluing this technology and leading to a higher risk ofstranded assets.
Strbac G, Konstantinidis CV, Moreno R, et al., 2015, It's All About Grids, IEEE POWER & ENERGY MAGAZINE, Vol: 13, Pages: 61-75, ISSN: 1540-7977
Ye Y, Papadaskalopoulos D, Strbac G, 2015, Factoring Flexible Demand Non-Convexities in Electricity Markets, IEEE TRANSACTIONS ON POWER SYSTEMS, Vol: 30, Pages: 2090-2099, ISSN: 0885-8950
Calvo JL, Ramirez Torrealba PJ, Tindemans S, et al., 2015, Cost-Benefit Analysis of Unreliable System Protection Scheme Operation, IEEE PowerTech 2015, Publisher: IEEE
System Protection Schemes (SPS) have the potential to greatly enhance the utilization of the network, often by automatically disconnecting generators in response to contingency events. However, malfunctions of such systems may expose the system to harmful blackouts. The operation of unreliable SPS is therefore subject to a cost-benefit balance between the benefits of increased system utilization and the risk of outages. This paper studies this trade-off in a year-round basis. The problem is firstly stated from a centralized perspective to probabilistically minimize the operational costs for a whole operating year. A case study based on a basic simple representation of the Great Britain system is considered. The results show great annual benefits from equipping the SPS with multiple generation disconnection systems, which are mainly associated with critical operating conditions. However, it is demonstrated that redundant SPS configurations do not necessarily reduce the levels of operational risk exposure.
Tindemans SH, Trovato V, Strbac G, 2015, Frequency control using thermal loads under the proposed ENTSO-E Demand Connection Code, PowerTech 2015, Publisher: IEEE, Pages: 1-6
Thermal loads such as refrigerators and electric space heaters use temperature hysteresis controllers that are insensitive to small temperature fluctuations. This results in an ability to modulate their power consumption, thus providing cost-effective frequency support, balancing services and energy arbitrage. In order to partially realise these benefits, ENTSO-E has proposed a mandatory frequency support service for thermal loads in its Network Code on Demand Connection. This is to be implemented as a proportional shift of the setpoint temperature in accordance with frequency deviations. In this paper we argue that this implementation choice results in an unpredictable response that depends strongly on controller details. Furthermore, it restricts the flexibility to implement advanced controllers that deliver multiple services simultaneously. We present a case study that demonstrates very different frequency response patterns from three controllers that are each compatible with the proposed Code. Alternative implementations of the code and controllers are presented to illustrate the scope for improvement.
Strbac G, Vasilakos Konstantinidis C, Moreno Vieyra R, et al., 2015, It’s All About Grids: The Importance of Transmission Pricing and Investment Coordination in Integrating Renewables, IEEE Power and Energy Magazine, ISSN: 1540-7977
Schofield J, Carmichael R, Tindemans S, et al., 2015, Experimental validation of residential consumer responsiveness to dynamic time-of-use pricing, 23rd International Conference on Electricity Distribution (CIRED)
This paper describes the first analysis from the LowCarbon London (LCL), residential dynamic time-of-use(dToU) pricing trial that took place in the London areaduring 2013. High price induced peak reductions fornetwork constraint management are investigatedalongside the temporal availability of demand responsefor supply balancing. By examining both these use caseswe identify potential conflicts between network andsystem objectives. Demand response results are stratifiedby a ranking metric for engagement with the dToU tariffas well as household occupancy and socio-economicclassification.
Ustinova T, Woolf M, Ortega Calderon JE, et al., 2015, Analysis of Customers' Performance in Industrial & Commercial Demand Side Response Trials, 23rd International Conference on Electricity Distribution (CIRED 2015)
Papadaskalopoulos D, Strbac G, 2015, Nonlinear and Randomized Pricing for Distributed Management of Flexible Loads, IEEE Transactions on Smart Grid, Vol: 7, Pages: 1137-1146, ISSN: 1949-3061
Price-based management of distributed energy resources within microgrids is continuously gaining ground due to scalability and privacy limitations of centralized architectures. However, the concentration of flexible loads' response to the lowest-priced periods yields inefficient solutions. A previously proposed measure imposing a flexibility restriction on flexible loads might raise acceptability and feasibility concerns by the users. This paper develops a novel fully price-based approach where this hard restriction is replaced by a soft nonlinear price signal. This signal is customized to the operating properties of the different flexible load types by penalizing the square of the demand and the duration of cycle delay of loads with continuously adjustable power levels and deferrable cycles, respectively. This approach is shown to produce more efficient solutions than the flexibility restriction measure for both types of loads. For the latter type, randomization of the nonlinear prices brings additional benefits, especially in low operating diversity cases. These contributions are supported by case studies on a microgrid test system with electric vehicles and wet appliances used as representative examples of the above flexible load types.
Trutnevyte E, Strachan N, Dodds PE, et al., 2015, Synergies and trade-offs between governance and costs in electricity system transition, Energy Policy, Vol: 85, Pages: 170-181, ISSN: 1873-6777
Affordability and costs of an energy transition are often viewed as the most influential drivers. Conversely, multi-level transitions theory argues that governance and the choices of key actors, such as energy companies, government and civil society, drive the transition, not only on the basis of costs. This paper combines the two approaches and presents a cost appraisal of the UK transition to a low-carbon electricity system under alternate governance logics. A novel approach is used that links qualitative governance narratives with quantitative transition pathways (electricity system scenarios) and their appraisal. The results contrast the dominant market-led transition pathway (Market Rules) with alternate pathways that have either stronger governmental control elements (Central Co-ordination), or bottom-up proactive engagement of civil society (Thousand Flowers). Market Rules has the lowest investment costs by 2050. Central Co-ordination is more likely to deliver the energy policy goals and possibly even a synergistic reduction in the total system costs, if policies can be enacted and maintained. Thousand Flowers, which envisions wider participation of the society, comes at the expense of higher investment and total system costs. The paper closes with a discussion of the policy implications from cost drivers and the roles of market, government and society.
Trovato V, Tindemans SH, Strbac G, 2015, Designing effective frequency response patterns for flexible thermostatic loads, 2015 IEEE 15th International Conference on Environment and Electrical Engineering (EEEIC), Publisher: IEEE, Pages: 1003-1008
Future power systems will have to integrate large amounts of wind and solar generation to drastically reduce CO2 emissions. Achieving this goal comes at the cost of a reduced level of the system inertia and an increased need for fast response services. Previous research has shown the effectiveness of thermostatically controlled loads (TCLs) providing frequency response, and the ability to accurately control the aggregate power consumption of TCLs. In this paper, we explore the design space of frequency response patterns of flexible TCLs. Two distinct frequency response implementations are presented. The first makes the TCLs' power consumption a linear function of system frequency and/or its rate of change; in the second, TCLs respond to a frequency event tracking a pre-programmed reference power profile. Computer simulations illustrate strengths and weaknesses of the proposed implementations in the context of the GB 2020 Gone Green scenario.
Pipelzadeh Y, Moreno Vieyra R, Chaudhuri B, et al., 2015, Role of Smart Grid Technology and Corrective Control in Enhancing Network Capacity Utilisation in Great Britain with HVDC links, CIGRE SYMPOSIUM, Publisher: CIGRE
A range of advanced, technically effective and economically efficient corrective (or postfault) actions has been proposed to release latent transmission network capacity of the existing system and thus reduce network congestion and accommodate increased connection of low-carbon generation. Although the increased use of corrective control that can manage post-fault transmission overloads has proven to be clearly beneficial from an economic perspective, there are concerns related to the consequent stability (angular and voltage) of transmission systems. In this context, this paper demonstrates various corrective control measures (that can be undertaken by Special Protection Schemes –SPS–) including rapid response of generation and demand against double line outages (N-2) under extremely high power transfer conditions. To demonstrate these benefits, case studies are carried out on a detailed (full) dynamic system model of the Great Britain (GB) transmission network in DIgSILENT, which includes the Western Line-Commutated Converter based High Voltage Direct Current (LCC-HVDC). The value of corrective control measures, based on generationand demand response accompanied by Transient Assistive Measures (TAM) such as rapid changes in DC power order to improve system stability is demonstrated. It is shown that such measures can significantly increase the power transfers through the England-Scotland inter-connector while maintaining N-2 security. Moreover, it is demonstrated that although a generation ramp up/down response is naturally slower than a step-change tripping action over generation and demand (tripping actions are preferred in SPS) and therefore more prone to transient instability problems, generation-only operational measures can be deployed to deal with double circuit (N-2) outages under extremely high power transfers, given that the right portfolio of TAM is deployed. Thus TAM can effectively enhance the set of correctivecontrol measures considered b
Strbac G, Hatziargyriou N, Lopes JP, et al., 2015, Microgrids, IEEE Power & Energy Magazine, Vol: 13, Pages: 35-43, ISSN: 1540-7977
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- Citations: 103
Teng F, Pudjianto D, Strbac G, et al., 2015, Potential value of energy storage in the UK electricity system, Proceedings of the ICE - Energy, Vol: 168, Pages: 107-117, ISSN: 1751-4223
This paper assesses the value of distributed energy storage and informs the business case for its multiple applications in the UK electricity system. In contrast to earlier studies that focus on the benefits of energy storage for system operation and development, this work analyses the value that it may deliver to the owner. For this purpose, three models are proposed and applied to analyse the benefit of energy storage with applications in energy and ancillary service markets, revenue maximisation in the context of feed-in tariffs and reduction of carbon dioxide emissions. A large set of studies is carried out to quantify the commercial and emissions benefits of energy storage for those applications. Sensitivity analysis across various scenarios is performed to understand the key drivers for the value of energy storage and how it is affected by energy storage parameters and other factors such as network constraints, prices of energy and ancillary services, and inherent energy system characteristics. A review of current and near-term storage technology costs and functionality is also presented.
Welsch M, Howells M, Hesamzadeh MR, et al., 2015, Supporting security and adequacy in future energy systems: The need to enhance long-term energy system models to better treat issues related to variability, INTERNATIONAL JOURNAL OF ENERGY RESEARCH, Vol: 39, Pages: 377-396, ISSN: 0363-907X
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- Citations: 46
De Paola A, Angeli D, Strbac G, 2015, Distributed Control of Micro-Storage Devices With Mean Field Games, IEEE Transactions on Smart Grid, Vol: 7, Pages: 1119-1127, ISSN: 1949-3061
This paper proposes a fully distributed control strategyfor the management of micro-storage devices that performenergy arbitrage. For large storage populations the problem canbe approximated as a differential game with infinite players(Mean Field Game). Through the resolution of coupled partialdifferential equations (PDEs), it is possible to determine, as afixed point, the optimal feedback strategy for each player andthe resulting price of energy if that strategy is applied. Oncethis price is calculated, it can be communicated to the deviceswhich are able to independently determine their optimal chargeprofile. Simulation results are provided, calculating the fixedpoint through numerical integration of the PDEs. The originalmodel is then extended in order to consider additional elementssuch as multiple population of devices and demand uncertainty.
Green RJ, Strbac, 2015, Storage in the energy market, IEEE Power and Energy Society General Meeting 2015
Strbac G, Aunedi M, Papadaskalopoulos D, et al., 2015, Modelling Requirements for Least-Cost and Market-Driven Whole-System Analysis
Konstantelos I, Strbac G, 2015, Valuation of flexible transmission investment options under uncertainty, IEEE Transactions on Power Systems, Vol: 30, Pages: 1047-1055, ISSN: 0885-8950
Significant uncertainty surrounds the future development of electricity systems, primarily in terms of size, location and type of new renewable generation to be connected. In this paper we assess the potential for flexible network technologies, such as phase-shifting transformers, and non-network solutions, such as energy storage and demand-side management, to constitute valuable interim measures within a long-term planning strategy. The benefit of such flexible assets lies not only in the transmission services provided but also in the way they can facilitate and de-risk subsequent decisions by deferring commitment to capital-intensive projects until more information on generation development becomes available. A novel stochastic formulation for transmission expansion planning is presented that includes consideration of investment in these flexible solutions. The proposed framework is demonstrated with a case study on the IEEE-RTS where flexible technologies are shown to constitute valuable investment options when facing uncertainties in future renewable generation development.
Strbac G, Konstantelos I, Moreno Vieyra R, 2015, Emerging Modelling Capabilities for System Operations, Emerging Modelling Capabilities for System Operations, Publisher: Institute of Engineering and Technology (IET)
The Institution of Engineering and Technology was commissioned by the Council of Science and Technology(CST) to research the emerging challenges for modelling electricity systems and how Britain’s capabilitieswould need to be adapted to assess electricity system resilience as GB makes the transition to a low carbonelectricity system.
Moreno R, Moreira R, Strbac G, 2015, A MILP model for optimising multi-service portfolios of distributed energy storage, Applied Energy, Vol: 137, Pages: 554-566, ISSN: 0306-2619
Energy storage has the potential to provide multiple services to several sectors in electricity industry and thus support activities related to generation, network and system operation. Hence aggregating the value delivered by storage to these sectors is paramount for promoting its efficient deployment in the near future, which will provide the level of flexibility needed to deal with the envisaged high renewables share and the increase in peak demand driven by transport and heating electrification. In this context, we develop a Mixed Integer Linear Programming (MILP) model to schedule operation of distributed storage by coordinating provision of a range of system services which are rewarded at different market prices. The model maximises distributed storage’s net profit while providing distribution network congestion management, energy price arbitrage and various reserve and frequency regulation services through both active and reactive power control. We demonstrate benefits associated with the coordination of these services and its impacts on commercial strategies to determine optimal multi-service portfolios in the long term. We also demonstrate the value of reactive power control to support not only distribution network congestion management, but also efficient trading of energy and balancing services which are usually treated through active power-only control. In addition, we use the model to price the service of distribution network congestion management and propose an efficient investment policy to upgrade distribution network capacity in the presence of distributed storage. Finally, several case studies under current market conditions in Great Britain (GB) demonstrate that distributed storage revenues associated with frequency control services are significantly more profitable.
Sanz IM, Chaudhuri B, Strbac G, et al., 2015, Corrective Control through Western HVDC link in Future Great Britain Transmission System, General Meeting of the IEEE-Power-and-Energy-Society, Publisher: IEEE, ISSN: 1944-9925
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- Citations: 3
Tsoutsos T, Tournaki S, Weiss I, et al., 2015, Photovoltaics competitiveness in Middle East and North Africa countries the European project PV PARITY, INTERNATIONAL JOURNAL OF SUSTAINABLE ENERGY, Vol: 34, Pages: 202-210, ISSN: 1478-6451
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- Citations: 3
Papadaskalopoulos D, Fatouros P, Strbac G, 2015, Addressing Demand Response Concentration under Dynamic Pricing, PowerTech, 2015 IEEE Eindhoven, Publisher: IEEE
Teng F, Strbac G, 2015, Evaluation of Synthetic Inertia Provision from Wind Plants, General Meeting of the IEEE-Power-and-Energy-Society, Publisher: IEEE, ISSN: 1944-9925
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- Citations: 6
Tindemans S, Djapic P, Schofield J, et al., 2014, Resilience performance of smart distribution networks, Report D4 for the “Low Carbon London” LCNF project
Trovato V, Tindemans SH, Strbac G, 2014, Security constrained economic dispatch with flexible thermostatically controlled loads, IEEE PES ISGT Europe 2014
Thermostatically controlled loads (TCLs) such as refrigerators and air conditioners are natural candidates for short term demand response. In this paper we quantify the value associated with the TCLs' ability to provide system security and transmission constraint management services. The analysis builds on recent results that enable the aggregate control of TCLs as a leaky storage unit. We incorporate this model in a security constrained economic dispatch (SCED) that minimizes the system operational cost of a two bus-bar system, subject to frequency response and transmission constraints. Further sensitivity studies assess the impact of different penetration levels of controllable loads and transmission flow constraints.
Strbac G, Pollitt M, Konstantinidis CV, et al., 2014, Electricity transmission arrangements in Great Britain: Time for change?, Energy Policy, Vol: 73, Pages: 298-311, ISSN: 0301-4215
In Great Britain (GB) and across Europe significant investment in electricity transmission is expected over the coming years as decarbonisation and market integration efforts are intensified. However, there is also significant uncertainty with the amount, location and timing of new generation connection, which in turn will drive the transmission investment needs. Given the absence of efficient market design, we identify three key areas of concern with the current transmission investment arrangements: (i) a mis-aligned incentives framework for transmission investment and operation; (ii) lack of coordination of investment and operation; and (iii) conflicts of interest. We then propose three options for future evolution of transmission regimes, which cover the full spectrum of institutional arrangements with respect to transmission planning and delivery, i.e. how and who plans, owns, builds and operates the transmission system. For each option we present: key characteristics; evolution of the current regimes; the ability of the option to address the concerns; and key strengths and weaknesses. Overall, we conclude in the case of GB (this conclusion could be extended to other European countries) that the most appropriate option would be that of an Independent System Operator (ISO) who would be responsible for planning and operating the transmission system.
Papadaskalopoulos D, Pudjianto D, Strbac G, 2014, Decentralized Coordination of Microgrids With Flexible Demand and Energy Storage, IEEE TRANSACTIONS ON SUSTAINABLE ENERGY, Vol: 5, Pages: 1406-1414, ISSN: 1949-3029
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- Citations: 55
Ye Y, Papadaskalopoulos D, Strbac G, 2014, Factoring Flexible Demand Non-Convexities in Electricity Markets, IEEE Transactions on Power Systems, Vol: 30, Pages: 2090-2099, ISSN: 0885-8950
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