Publications
547 results found
Wang S, Wang K, Teng F, et al., 2017, Optimal Allocation of ESSs for Mitigating Fluctuation in Active Distribution Network, 9th International Conference on Applied Energy (ICAE), Publisher: ELSEVIER SCIENCE BV, Pages: 3572-3577, ISSN: 1876-6102
Zhang X, Strbac G, Djapic P, et al., 2017, Optimization of Heat Sector Decarbonization Strategy through Coordinated Operation with Electricity System, Energy Procedia, Vol: 142, Pages: 2858-2863, ISSN: 1876-6102
De Paola A, Angeli D, Strbac G, 2017, Price-Based Schemes for Distributed Coordination of Flexible Demand in the Electricity Market, IEEE TRANSACTIONS ON SMART GRID, Vol: 8, Pages: 3104-3116, ISSN: 1949-3053
Tzelepis D, Rousis AO, Dysko A, et al., 2017, A new fault-ride-through strategy for MTDC networks incorporating wind farms and modular multi-level converters, INTERNATIONAL JOURNAL OF ELECTRICAL POWER & ENERGY SYSTEMS, Vol: 92, Pages: 104-113, ISSN: 0142-0615
De Paola A, Angeli D, Strbac G, 2017, A semi-decentralized scheme for integration of price-responsive appliances in the electricity market, 20th IFAC World Congress, Publisher: Elsevier, Pages: 6729-6736, ISSN: 1474-6670
A novel semi-decentralized control strategy is proposed for the integration in the power system of large populations of flexible loads, such as electric vehicles and “smart” appliances. To characterize the interactions between the single agents and their effects on the grid, a game theory framework is adopted. The price responsive appliances are modelled as competing players, characterizing a stable and efficient solution as a Nash equilibrium (no device has unilateral interest in changing its scheduled power consumption when the final electricity price is considered). We extend previous results on distributed control of flexible demand, proposing a partial centralization of the power scheduling at critical time instants. In this way, it is possible to ensure convergence to a Nash equilibrium for a wider range of scenarios, considering higher penetration levels of flexible demand and a wider range of parameters for the devices. The effectiveness of the proposed scheme is theoretically proved and its performance is evaluated in simulations, considering a future UK grid with high penetration of flexible demand.
Teng F, Aunedi M, Moreira R, et al., 2017, Business case for distributed energy storage, 24th International Conference & Exhibition on Electricity Distribution (CIRED), Pages: 1605-1608
© 2017 The Institution of Engineering and Technology. All rights reserved. This study presents the analysis carried out to quantify the value that distributed energy storage (ES) installation may deliver to its owner by simultaneously providing multiple services to a number of entities in the electricity sector. In this analysis, a full spectrum of services that ES may deliver are considered: energy arbitrage, balancing services, supporting low-carbon generation, network support, frequency regulation services, and capacity market. The results demonstrate that the net revenues from any single service would be difficult to justify the relatively high investment cost. Optimised provision of multiple services is therefore the key route for ES to make a profitable business case in the market. The potential synergies and conflicts between TSO and DNO services supplied by ES are also analysed.
Djapic P, Strbac G, 2017, Economically efficient distribution network design, 24th International Conference & Exhibition on Electricity Distribution (CIRED) 12-15 June 2017, Publisher: IET, Pages: 2241-2245
Decarbonisation of electricity sector, potential increase in electricity demand driven by incorporation of segments of heat and transport sectors, and conditional asset replacement drive the desire for cost-effectiveness of the use of existing assets and use of non-network solutions. A Working Group is tasked to review present and, if needed, propose a new security of supply standard. This study reports on the part of work carried within review. It describes drivers and objective for review, used analytical methodology, and relevant drivers. The results of case studies carried out on illustrative high-voltage networks topology show breakeven value of lost load and economically efficient degree of redundancy for different values of drivers. The study concludes with the key findings of the study.
Konstantelos I, Djapic P, Strbac G, et al., 2017, Contribution of energy storage and demand-side response to security of distribution networks, CIRED 2017, Publisher: IEEE, Pages: 1650-1654, ISSN: 2515-0855
The smart grid paradigm envisages the wide penetration of distributed energy resources, such as demand-side response (DSR) schemes and energy storage (ES). Despite their potential to improve security of supply at the distribution level, existing design standards in most jurisdictions consider solely conventional assets; conceptual and methodological gaps prevent DSR and ES from being embedded into formal network design practices. As such, the crucial question that arises is how to assess the security contribution of these technologies so as to level the playing field and encourage the transition to a smart grid. Here, the authors introduce two capacity metrics: equivalent firm capacity and equivalent load-carrying capability. The authors describe their application to DSR and ES, showcase results from the UK Power Networks' Smarter Network Storage and Low Carbon London projects, and provide suggestions on the incorporation of smart assets in future design standards.
Pudjianto D, Strbac G, Boyer D, 2017, Virtual power plant: managing synergies and conflicts between transmission system operator and distribution system operator control objectives, CIRED 24th International Conference on Electricity Distribution, Publisher: IET, Pages: 2049-2052, ISSN: 2515-0855
In this study, the implementation of virtual power plant (VPP) as a means to coordinate the use of distributed resources for different control objectives by transmission system operator and distribution system operator is described. In order to illustrate the concept, a range of illustrative studies demonstrating the application of VPP concept on a real 11 kV system in Brixton will be presented, using data from the Low Carbon London project. The studies demonstrate the changes in the operating characteristics of the VPP area over a range of system operating conditions.
Huyghues-Beaufond N, Jakeman A, Tindemans S, et al., 2017, Challenges in model and data merging for the implementation of a distribution network contingency analysis tool, 24th International Conference & Exhibition on Electricity Distribution (CIRED), Publisher: IET, Pages: 1621-1624, ISSN: 2515-0855
The electricity network in the South East of England has become more challenging to manage both for the transmission and distribution network operators due to increased distributed generation connection and increased power flows on transmission interconnectors to and from continental Europe. UK Power Networks (UKPN), the distribution network operator (DNO), has trialled for the first time online contingency analysis on a distribution network in Great Britain. The Kent Active System Management project aims to demonstrate the benefits of using a contingency analysis system for both operational and planning time frames. This study describes challenges and the recommended approach to overcome data exchange and data-quality challenges when developing a real-time power flow model from existing datasets. It provides a real-world example of dealing with data exchange and also highlights the need for transmission system operator/DNO coordination.
Djapic P, Strbac G, 2017, Value of load transfer capacity in distribution network design, IET International Conference on Resilience of Transmission and Distribution Networks (RTDN 2017), Publisher: Institution of Engineering and Technology
A fundamental review of the philosophy of distribution network operation and design is carried out to inform the industry, consumers, regulator and government, and facilitate a cost effective delivery of the UK Government energy policy objectives. Within the review potential benefit of load transfer capacity used to improve the reliability performance of the system is quantified. This is the subject addressed within this paper, showing used methodology and analysed case studies. The cost-benefit analysis is used to establish the reliability and cost performance of various network designs and emergency operation strategies. Potential benefit of load transfer capacity is calculated for different drivers: network loading, topology, voltage level, construction, and assets failure rate. It is found that the value of LTC is higher in low reliable networks and in systems with higher load. The value of LTC is less sensitive towards the number of supplied substations.
Rousis AO, Pipelzadeh Y, Green TC, et al., 2017, Benefits of distributed power generation for voltage support in GB transmission system: Case study on the south-east region, IET International Conference on Resilience of Transmission and Distribution Networks (RTDN 2017), Publisher: Institution of Engineering and Technology
Distributed Generation (DG) has lately attracted great interest by energy market players due to its potential for independent provision of active and reactive power. High penetration of renewable energy sources can, however, adversely affect the power system. As such, the power system needs to be reinforced or expanded to be able to successfully cope with potential issues. It has been argued, though, that support from DG could form part of the solution as a means of driving down network reinforcement costs. In this context, this work particularly focuses on the potential of DG to support the voltage of the transmission system by providing reactive power when requested to. The south-east region of National Grid's transmission system in Great Britain is used as a case study to demonstrate the benefit from utilization of DG. The main contribution of this paper is to specifically demonstrate that distributed allocation of reactive power sources can alleviate imminent voltage instability issues, while minimising transmission reinforcement costs.
Pudjianto D, Strbac G, Boyer D, 2017, Virtual power plant: managing synergies and conflicts between transmission system operator and distribution system operator control objectives, CIRED, ISSN: 2515-0855
Chilvers J, Foxon TJ, Galloway S, et al., 2017, Realising transition pathways for a more electric, low-carbon energy system in the United Kingdom: Challenges, insights and opportunities, PROCEEDINGS OF THE INSTITUTION OF MECHANICAL ENGINEERS PART A-JOURNAL OF POWER AND ENERGY, Vol: 231, Pages: 440-477, ISSN: 0957-6509
Strbac G, Aunedi M, Konstantelos I, et al., 2017, Opportunities for Energy Storage: Assessing Whole-System Economic Benefits of Energy Storage in Future Electricity Systems, IEEE Power and Energy Magazine, ISSN: 1540-7977
Pudjianto D, Strbac G, 2017, Assessing the value and impact of demand side response using whole-system approach, PROCEEDINGS OF THE INSTITUTION OF MECHANICAL ENGINEERS PART A-JOURNAL OF POWER AND ENERGY, Vol: 231, Pages: 498-507, ISSN: 0957-6509
This paper describes the whole-system based model called Whole-electricity System Investment Model to quantify the benefits of demand flexibility. Whole-electricity System Investment Model is a holistic and comprehensive electricity system analysis model, which simultaneously optimises the long-term investment decisions against real-time operation decisions taking into account the flexibility provided by demand. The optimisation considers the impact of demand side response across all power subsystems, i.e. generation, transmission and distribution systems, in a coordinated fashion. This allows the model to capture the potential conflicts and synergies between different applications of demand side response in supporting particularly intermittency management at the national level, improving capacity margin, and minimising the cost of electrification. The impact and value of demand side response driven by whole-system approach are compared against the impact and value of distribution system operator or transmission system operator centric (silo approaches) demand side response applications and the importance of control coordination between distribution system operator and transmission system operator for optimal demand side response is discussed and highlighted.
Djapic P, Strbac G, McKenna R, et al., 2017, Assessing the implications of socioeconomic diversity for low carbon technology uptake in electrical distribution networks, Applied Energy
Ye Y, Papadaskalopoulos, Moreira, et al., 2017, Strategic Capacity Withholding by Energy Storage in Electricity Markets, 12th IEEE PES PowerTech Conference, Publisher: IEEE
Abstract:Although previous work has demonstrated the ability of large energy storage (ES) units to exercise market power by withholding their capacity, it has adopted modeling approaches exhibiting certain limitations and has not analyzed the dependency of the extent of exercised market power on ES operating properties. In this paper, the decision making process of strategic ES is modeled through a bi-level optimization problem; the upper level determines the optimal extent of capacity withholding at different time periods, maximizing the ES profit, while the lower level represents endogenously the market clearing process. This problem is solved after converting it to a Mathematical Program with Equilibrium Constraints (MPEC) and linearizing the latter through suitable techniques. Case studies on a test market quantitatively analyze the extent of capacity withholding and its impact on ES profit and social welfare for different scenarios regarding the power and energy capacity of ES.
Fatouros P, Konstantelos I, Papadaskalopoulos D, et al., 2017, A stochastic dual dynamic programming approach for optimal operation of DER aggregators, IEEE PowerTech 2017, Publisher: IEEE
The operation of aggregators of distributed energy resources (DER) is a highly complex task that is affected by numerous factors of uncertainty such as renewables injections, load levels and market conditions. However, traditional stochastic programming approaches neglect information around temporal dependency of the uncertain variables due to computational tractability limitations. This paper proposes a novel stochastic dual dynamic programming (SDDP) approach for the optimal operation of a DER aggregator. The traditional SDDP framework is extended to capture temporal dependency of the uncertain wind power output, through the integration of an n-order autoregressive (AR) model. This method is demonstrated to achieve a better trade-off between solution efficiency and computational time requirements compared to traditional stochastic programming approaches based on the use of scenario trees.
Trovato V, Tindemans S, Strbac G, 2017, Understanding aggregate flexibility of thermostatically controlled loads, 12th IEEE Power and Energy Society PowerTech Conference 2017, Publisher: IEEE
Thermostatically controlled loads (TCLs) are an attractive source of responsive demand. This paper aims to provides a better understanding of the relation between thermal properties of TCLs and their suitability to provide energy arbitrage and frequency services. An approximate analysis on the basis of dimensionless parameters is used to visualise the relative abilities of eight classes of TCLs. The results are compared to those obtained from a formal optimisation approach, in the context of a GB case study. Additional studies are performed to investigate the impact of increasingly flexible frequency services and physical variations of TCL thermal models (thermal conductance and temperature deadband).
Ameli H, Abbasi E, Ameli MT, et al., 2017, A fuzzy-logic-based control methodology for secure operation of a microgrid in interconnected and isolated modes, International Transactions on Electrical Energy Systems, Vol: 27, ISSN: 2050-7038
Due to the global concerns regarding the climate change, integration of renewable energy sources is considered as a mitigation approach in electric power generation. This requires advanced frequency and voltage control methodologies to overcome the challenges especially in microgrids. This paper presents a 2-step frequency and voltage control methodology for microgrids with high penetration of variable renewable energy sources. An optimized Proportional-Integral controller is designed for a Superconductor Magnetic Energy Storage System to minimize the transient frequency deviations. In cases that the Superconductor Magnetic Energy Storage System cannot stabilize the microgrid frequency in the isolated mode, the microgrid controller activates the next level of the frequency control. In the second level, an intelligent fuzzy-logic frequency controller is designed to adjust controllable loads, controllable generation units as well as perform load shedding. In the interconnected mode, the microgrid controller is able to activate the second level to contribute to the system frequency control. Finally, an intelligent fuzzy-logic voltage controller, realized through distribution static synchronous compensator, is devised to control the voltage magnitude of the main feeders of the microgrid. In this work, a real-time operation algorithm for frequency as well as voltage control is proposed and has been tested by set of simulations on a low voltage benchmark network.
Tindemans S, Strbac G, 2017, Robust estimation of risks from small samples, Philosophical Transactions A: Mathematical, Physical and Engineering Sciences, Vol: 375, ISSN: 1471-2962
Data-driven risk analysis involves the inference of probability distributions from measured or simulated data. In the case of a highly reliable system, such as the electricity grid, the amount of relevant data is often exceedingly limited, but the impact of estimation errors may be very large. This paper presents a robust non-parametric Bayesian method to infer possible underlying distributions. The method obtains rigorous error bounds even for small samples taken from ill-behaved distributions. The approach taken has a natural interpretation in terms of the intervals between ordered observations, where allocation of probability mass across intervals is well specified, but the location of that mass within each interval is unconstrained. This formulation gives rise to a straightforward computational resampling method: Bayesian interval sampling. In a comparison with common alternative approaches, it is shown to satisfy strict error bounds even for ill-behaved distributions.
Giannelos S, Konstantelos I, Strbac G, 2017, A new class of planning models for option valuation of storage technologies under decision-dependent innovation uncertainty
Huyghues-Beaufond N, Jakeman A, Tindemans S, et al., 2017, Enhancing distribution network visibility using contingency analysis tools, International Conference on Resilience of Transmission and Distribution Networks (RTDN 2017), Publisher: IET
The East Kent area in the South East of England is the good example of how the uptake of distributed generation is changing the way electricity networks operate. This paper identifies the technical and operational challenges facing transmission and distribution networks in the East Kent area. It introduces the Kent Active System Management (KASM) project, which develops an online contingency analysis solution designed to assist UK Power Networks (UKPN) in maximising asset utilisation while maintaining the network security.
Jamieson M, Strbac G, Tindemans S, et al., 2017, A simulation framework to analyse weather-induced faults, RTDN 2017: International Conference on Resilience of Transmission and Distribution Networks, Publisher: IET
A framework for simulating weather-induced dependent faults across networks is proposed and demonstrated on a truncated GB network representative of the Scottish and Northern English network. Different weather scenarios are simulated on the test network considering location and wind-speed intensity, analysed using Monte-Carlo simulation. The sensitivity of the network to co-occurrence of faults is simulated by changing the sensitivity of network assets to wind speed via an exponential function. Greater sensitivity to wind speed induces a significant increase in outages, as reflected by risk metrics, specifically Expected Energy Not Served and Expected Maximum Load Shed.
Ameli H, Strbac, Qadrdan, 2017, Value of gas network infrastructure flexibility in supporting cost effective operation of power systems, Applied Energy, Vol: 202, Pages: 571-580, ISSN: 1872-9118
The electricity system balancing is becoming increasingly challenging due to the integration of Renewable Energy Sources (RES). At the same time, the dependency of electricity network on gas supply system is expected to increase, as a result of employing flexible gas generators to support the electricity system balancing. Therefore the capability of the gas supply system to deliver gas to generators under a range of supply and demand scenarios is of a great importance. As potential solutions to improve security of gas and electricity supply, this paper investigates benefits of employing flexible multi-directional compressor stations as well as adopting a fully integrated approach to operate gas and electricity networks. A set of case studies for a GB gas and electricity networks in 2030 have been defined to quantify the value of an integrated operation paradigm versus sequential operation of gas and electricity networks. The results indicate there are significant overall system benefits (up to 65% in extreme cases) to be gained from integrated optimization of gas and electricity systems, emphasizing the important role of gas network infrastructure flexibility in efficiently accommodating the expected expansion of intermittent RES in future power systems.
Moreira A, strbac G, Moreno R, et al., 2017, A Five-Level MILP Model for Flexible Transmission Network Planning under Uncertainty: A Min-Max Regret Approach, IEEE Transactions on Power Systems, Vol: 33, Pages: 486-501, ISSN: 0885-8950
The benefits of new transmission investment significantly depend on deployment patterns of renewable electricity generation that are characterized by severe uncertainty. In this context, this paper presents a novel methodology to solve the transmission expansion planning (TEP) problem under generation expansion uncertainty in a min-max regret fashion, when considering flexible network options and n 1 security criterion. To do so, we propose a five-level mixed integer linear programming (MILP) based model that comprises: (i) the optimal network investment plan (including phase shifters), (ii) the realization of generation expansion, (iii) the co-optimization of energy and reserves given transmission and generation expansions, (iv) the realization of system outages, and (v) the decision on optimal post-contingency corrective control. In order to solve the fivelevel model, we present a cutting plane algorithm that ultimately identifies the optimal min-max regret flexible transmission plan in a finite number of steps. The numerical studies carried out demonstrate: (a) the significant benefits associated with flexible network investment options to hedge transmission expansion plans against generation expansion uncertainty and system outages, (b) strategic planning-under-uncertainty uncovers the full benefit of flexible options which may remain undetected under deterministic, perfect information, methods and (c) the computational scalability of the proposed approach.
Teng F, Mu Y, Jia H, et al., 2017, Challenges on primary frequency control and potential solution from EVs in the future GB electricity system, Applied Energy, Vol: 194, Pages: 353-362, ISSN: 0306-2619
System inertia reduction, driven by the integration of renewables, imposes significant challenges on the primary frequency control. Electrification of road transport not only reduces carbon emission by shifting from fossil fuel consumption to cleaner electricity consumption, but also potentially provide flexibility to facilitate the integration of renewables, such as supporting primary frequency control. In this context, this paper develops a techno-economic evaluation framework to quantify the challenges on primary frequency control and assess the benefits of EVs in providing primary frequency response. A simplified GB power system dynamic model is used to analyze the impact of declining system inertia on the primary frequency control and the technical potential of primary frequency response provision from EVs. Furthermore, an advanced stochastic system scheduling tool with explicitly modeling of inertia reduction effect is applied to assess the cost and emission driven by primary frequency control as well as the benefits of EVs in providing primary frequency response under two representative GB 2030 system scenarios. This paper also identifies the synergy between PFR provision from EVs and “smart charging” strategy as well as the impact of synthetic inertia from wind turbines.
Konstantelos I, Moreno R, Strbac G, 2017, Coordination and uncertainty in strategic network investment: Case on the North Seas Grid, ENERGY ECONOMICS, Vol: 64, Pages: 131-148, ISSN: 0140-9883
The notion of developing a transnational offshore grid in the North Sea has attracted considerable attention in the past years due to its potential for substantial capital savings and increased scope for cross-border trade, sparking a European-wide policy debate on incentivizing integrated transmission solutions. However, one important aspect that has so far received limited attention is that benefits will largely depend on the eventual deployment pattern of electricity infrastructure which is currently characterized by severe locational, sizing and timing uncertainty. Given the lack of coordination between generation and network developments across Europe, there is a real risk for over-investment or a premature lock-in to options that exhibit limited adaptability. In the near future, important choices that have to be made concerning the network topology and amount of investment. In this paper we identify the optimal, in terms of reduced cost, network investment (including topology) in the North Seas countries under four deployment scenarios and five distinct policy choices differing in the level of offshore coordination and international market integration. By drawing comparisons between the study results, we quantify the net benefit of enabling different types of coordination under each scenario. Furthermore, we showcase a novel min–max regret optimization model and identify minimum regret first-stage commitments which could be deployed in the near future in order to enhance strategic optionality, increase adaptability to different future conditions and hence reduce any potential sub-optimality of the initial network design. In view of the above, we put forward specific policy recommendations regarding the adoption of a flexible anticipatory expansion framework for the identification of attractive investment opportunities under uncertainty.
Trovato V, Martinez Sanz I, Chaudhuri B, et al., 2017, Advanced control of thermostatic loads for rapid frequency response in Great Britain, IEEE Transactions on Power Systems, Vol: 32, Pages: 2106-2117, ISSN: 0885-8950
In the Great Britain power system, reduced system inertia (particularly during low demand conditions) and larger possible infeed loss would make grid frequency regulation extremely challenging in future. Traditional primary frequency response could be insufficient to limit the frequency variation within acceptable range. This paper shows that thermostatically controlled loads (TCLs) (domestic refrigerators) can be controlled without real-time communication and in a nondisruptive way to collectively enhance the network frequency response. The aggregated power consumption of TCLs, distributed across the system, could be controlled as a `linear' function of the locally measured frequency and its rate of change. Alternatively, their aggregated consumption could be made to follow a `pre-set' power profile depending on the estimated infeed loss. A novel technique for accurate estimation of infeed loss and consequent postfault TCL power reduction is also proposed. The effectiveness of the two TCL control strategies is compared for primary and secondary frequency response through a case study on a 36 busbar reduced equivalent of the Great Britain power system. The effect of spatial variation of transient frequencies and the time delays in frequency measurement and filtering are considered to show how the TCLs can realistically provide rapid frequency response.
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