92 results found
Hou X, Sun K, Zhang N, et al., 2022, Priority-driven self-optimizing power control scheme for interlinking converters of hybrid AC/DC microgrid clusters in decentralized manner, IEEE Transactions on Power Electronics, Vol: 37, Pages: 5970-5983, ISSN: 0885-8993
Hybrid AC/DC microgrid clusters are key building blocks of smart grid to support sustainable and resilient urban power systems. In microgrid clusters, the subgrid load-priorities and power quality requirements for different areas vary significantly. To realize optimal power exchanges among microgrid clusters, this paper proposes a decentralized self-optimizing power control scheme for interlinking converters (ILC) of hybrid microgrid clusters. A priority-driven optimal power exchange model of ILCs is built considering the priorities and capacities in subgrids. The optimization objective is to minimize the total DC-voltage/AC-frequency state deviations of subgrids. To realize the decentralized power flow control, an optimal-oriented quasi-droop control strategy of ILCs is introduced to not only achieve a flexible self-optimizing power flow management, but also provide an ancillary function of voltage support. Consequently, as each of ILCs only monitors the local AC-side frequency and DC-side voltage signals, the whole optimal power control of the wide-area microgrid clusters is achieved in a decentralized manner without any communication link. Thus, the proposed control algorithm has the features of decreased cost, increased scalability, reduced geographic restrictions and high resilience in terms of communication faults. Finally, the proposed method is validated by case studies with four interconnected microgrids through hardware-in-loop tests.
Bellizio F, Xu W, Qiu D, et al., 2022, Transition to Digitalized Paradigms for Security Control and Decentralized Electricity Market, PROCEEDINGS OF THE IEEE, ISSN: 0018-9219
Hua W, Jiang J, Sun H, et al., 2022, Consumer-centric decarbonization framework using Stackelberg game and Blockchain, APPLIED ENERGY, Vol: 309, ISSN: 0306-2619
Ge P, Teng F, Konstantinou C, et al., 2022, A resilience-oriented centralised-to-decentralised framework for networked microgrids management, Applied Energy, Vol: 308, ISSN: 0306-2619
This paper proposes a cyber–physical cooperative mitigation framework to enhance power systems resilience against power outages caused by extreme events, e.g., earthquakes and hurricanes. Extreme events can simultaneously damage the physical-layer electric power infrastructure and the cyber-layer communication facilities. Microgrid (MG) has been widely recognised as an effective physical-layer response to such events, however, the mitigation strategy in the cyber lay is yet to be fully investigated. Therefore, this paper proposes a resilience-oriented centralised-to-decentralised framework to maintain the power supply of critical loads such as hospitals, data centres, etc., under extreme events. For the resilient control, controller-to-controller (C2C) wireless network is utilised to form the emergency regional communication when centralised base station being compromised. Owing to the limited reliable bandwidth that reserved as a backup, the inevitable delays are dynamically minimised and used to guide the design of a discrete-time distributed control algorithm to maintain post-event power supply. The effectiveness of the cooperative cyber–physical mitigation framework is demonstrated through extensive simulations in MATLAB/Simulink.
O'Malley C, Badesa L, Teng F, et al., 2021, Probabilistic scheduling of UFLS to secure credible contingencies in low inertia systems, IEEE Transactions on Power Systems, ISSN: 0885-8950
The reduced inertia levels in low-carbon power grids necessitate explicit constraints to limit frequency's nadir and rate of change during scheduling. This can result in significant curtailment of renewable energy due to the minimum generation of thermal plants that are needed to provide frequency response (FR) and inertia. Additional consideration of fast FR, a dynamically reduced largest loss and under frequency load shedding (UFLS) allows frequency security to be achieved more cost effectively. This paper derives a novel constraint from the swing equation to contain the frequency nadir using all of these services. The expected cost of UFLS is found probabilistically to facilitate its comparison to the other frequency services. We demonstrate that this constraint can be accurately and conservatively approximated for moderate UFLS levels with a second order cone (SOC), resulting in highly tractable convex problems. Case studies performed on a Great Britain 2030 system demonstrate that UFLS as an option to contain single plant outages can reduce annual operational costs by up to 559m, 52% of frequency security costs. The sensitivity of this value to wind penetration, abundance of alternative frequency services, UFLS amount and cost is explored.
Badesa L, Teng F, Strbac G, 2021, Conditions for regional frequency stability in power system scheduling—Part II: application to unit commitment, IEEE Transactions on Power Systems, Vol: 36, Pages: 5567-5577, ISSN: 0885-8950
In Part I of this paper we have introduced the closed-form conditions for guaranteeing regional frequency stability in a power system. Here we propose a methodology to represent these conditions in the form of linear constraints and demonstrate their applicability by implementing them in a generation-scheduling model. This model simultaneously optimises energy production and ancillary services for maintaining frequency stability in the event of a generation outage, by solving a frequency-secured Stochastic Unit Commitment (SUC). We consider the Great Britain system, characterised by two regions that create a non-uniform distribution of inertia: England in the South, where most of the load is located, and Scotland in the North, containing significant wind resources. Through several case studies, it is shown that inertia and frequency response cannot be considered as system-wide magnitudes in power systems that exhibit inter-area oscillations in frequency, as their location in a particular region is key to guarantee stability. In addition, securing against a medium-sized loss in the low-inertia region proves to cause significant wind curtailment, which could be alleviated through reinforced transmission corridors. In this context, the proposed constraints allow to find the optimal volume of ancillary services to be procured in each region.
Chu Z, Zhang N, Teng F, 2021, Frequency-Constrained Resilient Scheduling of Microgrid: A Distributionally Robust Approach, IEEE TRANSACTIONS ON SMART GRID, Vol: 12, Pages: 4914-4925, ISSN: 1949-3053
Badesa L, Teng F, Strbac G, 2021, Conditions for regional frequency stability in power system scheduling—Part I: theory, IEEE Transactions on Power Systems, Vol: 36, Pages: 5558-5566, ISSN: 0885-8950
This paper considers the phenomenon of distinct regional frequencies recently observed in some power systems. First, a reduced-order mathematical model describing this behaviour is developed. Then, techniques to solve the model are discussed, demonstrating that the post-fault frequency evolution in any given region is equal to the frequency evolution of the Centre Of Inertia plus certain inter-area oscillations. This finding leads to the deduction of conditions for guaranteeing frequency stability in all regions of a power system, a deduction performed using a mixed analytical-numerical approach that combines mathematical analysis with regression methods on simulation samples. The proposed stability conditions are linear inequalities that can be implemented in any optimisation routine allowing the co-optimisation of all existing ancillary services for frequency support: inertia, multi-speed frequency response, load damping and an optimised largest power infeed. This is the first reported mathematical framework with explicit conditions to maintain frequency stability in a power system exhibiting inter-area oscillations in frequency.
Zhao P, Gu C, Cao Z, et al., 2021, Data-Driven Multi-Energy Investment and Management Under Earthquakes, IEEE TRANSACTIONS ON INDUSTRIAL INFORMATICS, Vol: 17, Pages: 6939-6950, ISSN: 1551-3203
Xiang Y, Wang Y, Xia S, et al., 2021, Charging Load Pattern Extraction for Residential Electric Vehicles: A Training-Free Nonintrusive Method, IEEE TRANSACTIONS ON INDUSTRIAL INFORMATICS, Vol: 17, Pages: 7028-7039, ISSN: 1551-3203
Yong P, Zhang N, Hou Q, et al., 2021, Evaluating the Dispatchable Capacity of Base Station Backup Batteries in Distribution Networks, IEEE TRANSACTIONS ON SMART GRID, Vol: 12, Pages: 3966-3979, ISSN: 1949-3053
Zhao J, Wu Q, Hatziargyriou ND, et al., 2021, Decentralized Data-Driven Load Restoration in Coupled Transmission and Distribution System With Wind Power, IEEE TRANSACTIONS ON POWER SYSTEMS, Vol: 36, Pages: 4435-4444, ISSN: 0885-8950
Li H, Qiao Y, Lu Z, et al., 2021, Frequency-Constrained Stochastic Planning Towards a High Renewable Target Considering Frequency Response Support From Wind Power, IEEE TRANSACTIONS ON POWER SYSTEMS, Vol: 36, Pages: 4632-4644, ISSN: 0885-8950
Heylen E, Teng F, Strbac G, 2021, Challenges and opportunities of inertia estimation and forecasting in low-inertia power systems, Renewable and Sustainable Energy Reviews, Vol: 147, Pages: 1-12, ISSN: 1364-0321
Accurate inertia estimates and forecasts are crucial to support the system operation in future low-inertia power systems. A large literature on inertia estimation methods is available. This paper aims to provide an overview and classification of inertia estimation methods. The classification considers the time horizon the methods are applicable to, i.e., offline post mortem, online real time and forecasting methods, and the scope of the inertia estimation, e.g., system-wide, regional, generation, demand, individual resource. The framework presented in this paper facilitates objective comparisons of the performance of newly developed or improved inertia estimation methods with the state-of-the-art methods in their respective time horizon and with their respective scope. Moreover, shortcomings of the existing inertia estimation methods have been identified and suggestions for future work have been made.
Pan G, Gu W, Hu Q, et al., 2021, Cost and low-carbon competitiveness of electrolytic hydrogen in China, ENERGY & ENVIRONMENTAL SCIENCE, Vol: 14, Pages: 4868-4881, ISSN: 1754-5692
Chu Z, Teng F, 2021, Short circuit current constrained UC in the high IBG-penetrated power systems, IEEE Transactions on Power Systems, Vol: 36, Pages: 3776-3785, ISSN: 0885-8950
Inverter Based Generators (IBGs) have been increasing significantly in power systems. Due to the demanding thermal rating of Power Electronics (PE), their contribution to the system Short Circuit Current (SCC) is much less than that from the conventional Synchronous Generators (SGs) thus reducing the system strength and posing challenges to system protection and stability. This paper proposes a Unit Commitment (UC) model with SCC constraint in high IBG-penetrated systems to ensure minimum operation cost while maintaining the SCC level at each bus in the system. The SCC from synchronous generators as well as the IBGs are explicitly modeled in the formulation leading to an SCC constraint involving decision-dependent matrix inverse. This highly nonlinear constraint is further reformulated into linear form conservatively. The influence of the SCC constraint on the system operation and its interaction with the frequency regulation are demonstrated through simulations on IEEE 30- and 118-bus systems.
Li P, Chen B, Chu Z, et al., 2021, Estimation of Time-varying Frequency and its Rate of Change in Low-inertia Power Systems
In this paper, a hierarchical estimation scheme is designed to track the frequency and its rate of change of non-stationary power signals. The frequency is retrieved by a kernel-based parameter estimator in the first step. Subsequently, the frequency estimates are injected into a kernel-based numerical differentiator to extract its changing rate. Thanks to the deployed Volterra integral operator and suitably designed kernel-functions, the proposed estimator can achieve very fast convergence speed without compromising the robustness against noise. Therefore, the real-time estimates are able to follow the time-varying frequency and its rate of change with satisfactory accuracy. The effectiveness and robustness of the proposed method are verified by numerical experiments considering typical practical scenarios under the disturbance of noise. The results of the proposed method are compared with a highly-concerned quadrature phase-locked-loop (QPLL) method.
Tosatto A, Misyris G, Junyent-Ferre A, et al., 2021, Towards optimal coordination between regional groups: HVDC supplementary power control, IEEE Transactions on Power Systems, Vol: 37, Pages: 1-1, ISSN: 0885-8950
With Europe dedicated to limiting climate change and greenhouse gas emissions, large shares of Renewable Energy Sources (RES) are being integrated in the national grids, phasing out conventional generation. The new challenges arising from the energy transition will require a better coordination between neighboring system operators to maintain system security. To this end, this paper studies the benefit of exchanging primary frequency reserves between asynchronous areas using the Supplementary Power Control (SPC) functionality of High-Voltage Direct-Current (HVDC) lines. First, we focus on the derivation of frequency metrics for asynchronous AC systems coupled by HVDC interconnectors. We compare two different control schemes for HVDC converters, which allow for unilateral or bilateral exchanges of reserves between neighboring systems. Second, we formulate frequency constraints and include them in a unit commitment problem to ensure the N-1 security criterion. A data-driven approach is proposed to better represent the frequency nadir constraint by means of cutting hyperplanes. Our results suggest that the exchange of primary reserves through HVDC can reduce up to 10% the cost of reserve procurement while maintaining the system N-1 secure.
Higgins M, Mayes K, Teng F, 2021, Enhanced cyber-physical security using attack-resistant cyber nodes and event-triggered moving target defence, IET Cyber-Physical Systems: Theory & Applications, Vol: 6, Pages: 12-26, ISSN: 2398-3396
A cyber‐physical authentication strategy to protect power system infrastructure against false data injection (FDI) attacks is outlined. The authors demonstrate that it is feasible to use small, low‐cost, yet highly attack‐resistant security chips as measurement nodes, enhanced with an event‐triggered moving target defence (MTD), to offer effective cyber‐physical security. At the cyber layer, the proposed solution is based on the MULTOS Trust‐Anchor chip, using an authenticated encryption protocol, offering cryptographically protected and chained reports at up to 12/s. The availability of the Trust‐Anchors allows the grid controller to delegate aspects of passive anomaly detection, supporting local as well as central alarms. In this context, a distributed event‐triggered MTD protocol is implemented at the physical layer to complement cyber side enhancement. This protocol applies a distributed anomaly detection scheme based on Holt‐Winters seasonal forecasting in combination with MTD implemented via inductance perturbation. The scheme is shown to be effective at preventing or detecting a wide range of attacks against power system measurement system.
Ge P, Zhu Y, Green TC, et al., 2021, Resilient secondary voltage control of islanded microgrids: an ESKBF-based distributed fast terminal sliding mode control approach, IEEE Transactions on Power Systems, Vol: 36, Pages: 1059-1070, ISSN: 0885-8950
This paper proposes a distributed secondary voltage control method based on extended state Kalman-Bucy filter (ESKBF) and fast terminal sliding mode (FTSM) control for the resilient operation of an islanded microgrid (MG) with inverter-based distributed generations (DGs). To tackle the co-existence of multiple uncertainties, a unified modelling framework is proposed to represent the set of different types of disturbances, including parameter perturbation, measurement noise, and immeasurably external variables, by an extended state method. Kalman-Bucy filter is then applied to accurately estimate the state information of the extended DG model. In addition, based on the accurate estimation, a fast terminal sliding mode (FTSM) surface with terminal attractors is designed to maintain the system stability and accelerate the convergence of consensus tracking, which significantly improves the performance of secondary voltage control under both normal and plug-and-play operation. Finally, case studies are conducted in both MATLAB/Simulink and an experimental testbed to demonstrate the effectiveness of the proposed method.
Heylen E, Browell J, Teng F, 2021, Probabilistic Day-ahead Inertia Forecasting, IEEE Transactions on Power Systems, ISSN: 0885-8950
Power system inertia is declining and is increasingly variable and uncertain in regions where the penetration of non-synchronous generation and interconnectors is growing. This presents a challenge to power system operators who must take appropriate actions to ensure the stability and security of power systems relying on short-term forecasts of the system's inertial response. Existing models to forecast inertia fail to quantify uncertainty, which may prevent their utilization given the risk aversion of the system operators when handling stability issues. This paper is the first to develop a model to produce calibrated, data-driven probabilistic forecasts of the inertia contribution of transmission-connected synchronous generators. The model provides a necessary tool for system operators to quantify forecast uncertainty, allowing them to manage the risk of frequency instability cost-effectively. The paper demonstrates that the assumption of a Gaussian distribution of uncertainty applied in existing models is not acceptable to accurately forecast the inertial response and provides a satisfactory forecast model by combining non-parametric density forecasting with parametric tail distributions. Moreover, the paper shows that satisfactory predictive performance can only be achieved by adopting a rolling horizon forecast approach to deal with the rapidly changing characteristics of the inertial response in power systems.
Higgins M, Zhang J, Zhang N, et al., 2021, Topology Learning Aided False Data Injection Attack without Prior Topology Information, ISSN: 1944-9925
False Data Injection (FDI) attacks against power system state estimation are a growing concern for operators. Previously, most works on FDI attacks have been performed under the assumption of the attacker having full knowledge of the underlying system without clear justification. In this paper, we develop a topology-learning-aided FDI attack that allows stealthy cyber-attacks against AC power system state estimation without prior knowledge of system information. The attack combines topology learning technique, based only on branch and bus power flows, and attacker-side pseudo-residual assessment to perform stealthy FDI attacks with high confidence. This paper, for the first time, demonstrates how quickly the attacker can develop full-knowledge of the grid topology and parameters and validates the full knowledge assumptions in the previous work.
Ge P, Konstantinou C, Teng F, 2021, Cyber-Physical Disaster Response of Power Supply Using a Centralised-to-Distributed Framework, Pages: 214-219
This paper proposes a cyber-physical cooperative recovery framework to maintain critical power supply, enhancing power systems resilience under extreme events such as earthquakes and hurricanes. Extreme events can possibly damage critical infrastructure in terms of power supply, on both cyber and physical layers. Microgrid (MG) has been widely recognised as the physical-side response to such blackouts, however, the recovery of cyber side is yet fully investigated, especially the cooperatively recovery of cyber-physical power supply. Therefore, a centralised-to-distributed resilient control framework is designed to maintain the power supply of critical loads. In such resilient control, controller-to-controller (C2C) wireless network is utilised to form the emergency distributed communication without a centralised base station. Owing to the limited reliable bandwidth that can be employed in C2C networks, the inevitable delay is considered in designing a discrete control framework, and the corresponding stability criteria are given quantitatively. Finally, the cyber-physical recovery framework is demonstrated effectively through simulations in MATLAB/Simulink.
Chhachhi S, Teng F, 2021, Market Value of Differentially-Private Smart Meter Data, IEEE-Power-and-Energy-Society Innovative Smart Grid Technologies Conference (ISGT), Publisher: IEEE, ISSN: 2167-9665
Xiang Y, Meng J, Huo D, et al., 2020, Reliability-oriented optimal planning of charging stations in electricity-transportation coupled networks, IET RENEWABLE POWER GENERATION, Vol: 14, Pages: 3690-3698, ISSN: 1752-1416
Yang J, Zhang S, Xiang Y, et al., 2020, LSTM auto-encoder based representative scenario generation method for hybrid hydro-PV power system, IET GENERATION TRANSMISSION & DISTRIBUTION, Vol: 14, Pages: 5935-5943, ISSN: 1751-8687
Luo J, Teng F, Bu S, 2020, Stability-constrained power system scheduling: a review, IEEE Access, Vol: 8, Pages: 219331-219343, ISSN: 2169-3536
Power system scheduling mainly concerns economic optimization issues of the power system, which is also commonly known as the unit commitment (UC) problem. However, improper planning in the generation schedule may pose a negative impact on power system stability. Additionally, the trend of large-scale integration of renewable energy in the future power system brings critical challenges to power system stability. In consequence, it is necessary to integrate the stability constraints into power system scheduling. According to the classic classification of power system stability (i.e. voltage stability, frequency stability, and rotor angle stability), stability constraints can be constructed accordingly to guarantee system stability when solving UC problems, which ensures both the economic efficiency and technical feasibility of the UC solutions. This paper reviews typical stability constraints and how to apply these constraints in solving UC problems. Representative works are summarized to provide a guidance for addressing the stability constrained scheduling problems in the future power system operation.
Zhang Y, Shan Q, Li T, et al., 2020, Energy Dispatch Scheme on Ship Integrated Energy System with Photovoalatic and CHP, Pages: 3339-3344
Maritime industry with huge energy consumption and pollution, has become an urgent problem, which promotes us to consider the ship integrated energy system (IES) . A kind of ship IES has been concerned in this paper, which consists of electrical and heating system. An energy dispatch scheme has been proposed as well, which promotes the coupling efficiency of electrical and heating energy for ships. This paper integrates combined heating and power device (CHPD), energy storage system (ESS), renewable generation device like photovolatic in the energy system (ES) to ensure the eco-friendly sailing. Moreover, a penalty coefficient, relating to the state and outputs of ESS, has been considered in the dispatch scheme which can promote cost function to be more flexible. Through the proposed power dispatch scheme, the heating and electrical power outputs of each generation device during every period of time can be dispatched efficiently. Corresponding objective function with correlation parameters can be solved by dynamic programming (DP). Finally, the simulation illustrates the effectiveness of the proposed scheme.
Badesa L, Teng F, Strbac G, 2020, Optimal portfolio of distinct frequency response services in low-inertia systems, IEEE Transactions on Power Systems, Vol: 35, Pages: 4459-4469, ISSN: 0885-8950
A reduced level of system inertia due to renewable integration increases the need for cost-effective provision of ancillary services, such as Frequency Response (FR). In this paper a closed-form solution to the differential equation describing frequency dynamics is proposed, which allows to obtain frequency-security algebraic constraints to be implemented in optimization routines. This is done while considering any finite number of FR services with distinguished characteristics, such as different delivery times and activation delays. The problem defined by these frequency-security constraints can be formulated as a Mixed-Integer Second-Order Cone Program (MISOCP), which can be efficiently handled by off-the-shelf conic optimization solvers. This paper also takes into account the uncertainty in inertia contribution from the demand side by formulating the frequency-security conditions as chance constraints, for which an exact convex reformulation is provided. Finally, case studies highlighting the effectiveness of this frequency-secured formulation are presented.
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