publications
Most of the source papers can be found on my ResearchGate profile.
2024
- Electric Vehicles Charging Time Constrained Deliverable Provision of Secondary Frequency RegulationJinning Wang, Fangxing Li, Xin Fang, and 4 more authorsIEEE Transactions on Smart Grid, 2024
Aggregation of electric vehicles (EVs) is a promising technique for providing secondary frequency regulation (SFR) in highly renewable energy-penetrated power systems. Equipped with energy storage devices, EV aggregation can provide reliable SFR. However, the main challenge is to guarantee reliable intra-interval SFR capacities and inter-interval delivery following the automatic generation control (AGC) signal. Furthermore, aggregated EV SFR provision will be further complicated by the EV charging time anxiety because SFR provision might extend EV’s charging time. This paper proposes a deliverable EV SFR provision with a charging-time-constrained control strategy. First, a charging-time-constrained EV aggregation is proposed to address the uncertainty of EV capacity based on the state-space model considering the charging-time restriction of EV owners. Second, a real-time economic dispatch and time domain simulation (RTED-TDS) cosimulation framework is proposed to verify financial results and the dynamic performance of the EV SFR provision. Last, the proposed charging time-constrained EV aggregation is validated on the IEEE 39-bus system. The results demonstrate that with charging time-constrained EV aggregation, the dynamic performance of the system can be improved with a marginal increase in total cost. More importantly, the charging time constraint can be respected in the proposed SFR provision of the EV aggregation.
- Distributed cooperation optimization of multi-microgrids under grid tariff uncertainty: A nash bargaining game approach with cheating behaviorsJianan Du, Xiaoqing Han, and Jinning WangInternational Journal of Electrical Power & Energy Systems, Jan 2024
Multi-microgrid system (MMGs) has drawn extensive attention recently because of its high energy efficiency. However, MMGs’ operational efficiency can be affected by market price fluctuations and intermittent renewable energy. This paper proposes an energy-sharing model based on the Nash bargaining game between multi-microgrids. The proposed model provides a robust energy trading schedule to deal with uncertainties brought by grid tariffs and renewable energy. To ensure the model is tractable, the original game problem is equivalently converted into a system benefit maximization subproblem and an additional profit distribution subproblem to get optimal energy sharing power and prices. In addition, microgrid has the motivation to cheat for maximizing its benefits which may lead to the breakdown of cooperation. Furthermore, cheating behaviors in energy transaction are analyzed; the energy sharing scheme based on cheating equilibrium is derived by proposing an intermediary transaction mode. Finally, the alternating direction method of multipliers (ADMM) is used to protect the players’ privacies in a distributed way. Simulation results show that the proposed model can realize stable cooperation, effectively reduce operating costs and immunize against multiple uncertainties and cheating behaviors.
- Siting and Sizing of DG Units Considering Energy Equity: Model, Solution, and GuidelinesChenchen Li, Fangxing Li, Sufan Jiang, and 2 more authorsIEEE Transactions on Smart Grid, Jan 2024
Low-income communities have challenges obtaining equal access to electricity, so it is important to implement energy justice. Meanwhile, increasing installations of distributed generators (DGs) in distribution systems is a viable means to promote energy equity. Therefore, this work explores a new planning method for a DG units’ siting and sizing problem with an energy equity constraint embedded in the model, and concluding guidelines can be used as a rule of thumb for future DG planning considering energy equity. In this paper, first, the DG siting and sizing problem is formulated as a stochastic bi-level model, where energy equity is considered as an energy burden constraint. The upper level determines the optimal sites and sizes of DGs under investment and energy burden constraints, while the lower level optimizes the distribution operation. Next, a solution method is proposed by applying the Karush-Kuhn-Tucker optimality conditions to convert the stochastic bi-level model to a single-level model. A decomposition approach and Progressive Hedging Algorithm are used to further simplify the single-level model into multiple easy-to-solve subproblems. Finally, numerical studies are performed on two systems to verify the effectiveness of the proposed model. Technical rule-of-thumb guidelines are presented for siting and sizing DGs considering energy equity.
2023
- DiME and AGVis: A Distributed Messaging Environment and Geographical Visualizer for Large-Scale Power System SimulationNicholas Parsly, Jinning Wang, Nick West, and 3 more authorsIn 2023 North American Power Symposium (NAPS), Oct 2023
This paper introduces the messaging environment and the geographical visualization tools of the CURENT Large-scale Testbed (LTB) that can be used for large-scale power system closed-loop simulation. First, Distributed Messaging Environment (DiME) is presented as an asynchronous shared workspace to enable high-concurrent data exchange. Second, Another Grid Visualizer (AGVis) is presented as a geovisualization tool that facilitates the visualization of real-time power system simulation. Third, case studies show the use of DiME and AGVis in power system research. The results demonstrate that, with the modular structure of DiME and AGVis, the LTB is capable of not only federal use for real-time, large-scale power system simulation, but also independent use for customized power system research.
- Virtual Inertia Scheduling (VIS) for Real-time Economic Dispatch of IBRs-penetrated Power SystemsBuxin She, Fangxing Li, Hantao Cui, and 3 more authorsIEEE Transactions on Sustainable Energy, Oct 2023
A new concept called virtual inertia scheduling (VIS) is proposed to efficiently handle the increasing penetration of inverter-based resources (IBRs) in power systems. VIS is an inertia management framework that targets security-constrained and economy-oriented inertia scheduling and generation dispatch with a large scale of renewable generations. Specifically, it determines the appropriate power setting points and reserved capacities of synchronous generators and IBRs, as well as the control modes and control parameters of IBRs to provide secure and cost-effective inertia support. First, a uniform system model is employed to quantify the frequency dynamics of the IBRs-penetrated power systems after disturbances. Leveraging this model, the s -domain and time-domain analytical responses of IBRs with inertia support capability are derived. Then, VIS-based real-time economic dispatch (VIS-RTED) is formulated to minimize generation and reserve costs, with full consideration of dynamic frequency constraints and derived inertia support reserve constraints. The virtual inertia and damping of IBRs are formulated as decision variables. A deep learning-assisted linearization approach is further employed to address the non-linearity of dynamic constraints. Finally, VIS-RTED is demonstrated on a two-machine system and a modified IEEE 39-bus system. A full-order time-domain simulation is performed to verify the scheduling results and ensure their feasibility.
- Decentralized and Coordinated V-f Control for Islanded Microgrids Considering DER Inadequacy and Demand ControlBuxin She, Fangxing Li, Hantao Cui, and 4 more authorsIEEE Transactions on Energy Conversion, Sep 2023
This paper proposes a decentralized and coordinated voltage and frequency (V-f) control framework for islanded microgrids, with full consideration of the limited capacity of distributed energy resources (DERs) and V-f dependent load. First, the concept of DER inadequacy is illustrated with the challenges it poses. Then, a decentralized and coordinated control framework is proposed to regulate the output of inverter-based generations and reallocate limited DER capacity for V-f control. The control framework is composed of a power regulator and a V-f regulator, which generates the supplementary signals for the primary controller. The power regulator regulates the output of grid-forming inverters according to the real-time capacity constraints of DERs, while the V-f regulator improves the V-f deviation by leveraging the load sensitivity to V-f. Next, the static feasibility and small signal stability of the proposed method are rigorously proven through mathematical formulation and eigenvalue analysis. Finally, a MATLAB-Simulink simulation demonstrates the functionalities of the control framework. A few goals are fulfilled within the decentralized and coordinated framework, such as making the best use of limited DERs’ capacity, enhancing the DC side stability of inverter-based generations, and reducing involuntary load shedding.
2022
- Disturbance Propagation in Power Grids With High Converter PenetrationHantao Cui, Stavros Konstantinopoulos, Denis Osipov, and 4 more authorsProceedings of the IEEE, Sep 2022
High penetration of converter-interfaced renewable energy resources will significantly change the swing dynamics between synchronous generators (SGs) in future power systems. This article examines the impact of high converter penetration on wave-like disturbance propagation arising from sudden generator and load losses in radial (1-D) and meshed (2-D) power systems. To keep the uniformity assumption as converters are introduced, the rating of each SG is decreased with a converter resource making up for the reduction. Numerical simulations demonstrate that as the penetration level of constant-power grid-following (GFL) converters increases, the speed of disturbance propagation increases due to the reduced system inertia. Naturally, converters with the capabilities to positively respond to disturbances would in turn reduce the propagation speed. Analytical studies based on continuum models are presented for the 2-D system with SGs and constant-power GFL converters in order to visualize the disturbance propagation and validate numerical simulations based on differential-algebraic equations. In addition, fast active power control of converters can slow down the electromechanical wave (EMW) propagation and even contain it. These concepts are illustrated on the idealized radial and meshed systems and a reduced model of the U.S. eastern interconnection.
- Transmission-Distribution Dynamic Co-simulation of Electric Vehicles Providing Grid Frequency ResponseYijing Liu, Thomas J. Overbye, Wenbo Wang, and 4 more authorsIn 2022 IEEE Power & Energy Society General Meeting (PESGM), Jul 2022
This paper investigates the impacts of electric vehicles (EVs) on power system frequency regulation based on an open-source transmission-and-distribution (T&D) dynamic cosimulation framework. The development of an EV dynamic model based on an Western Electricity Coordinating Council dynamic model is introduced first, then the T&D dynamic co-simulation platform is described. The advantage of the overall platform is that distributed energy resources, such as distributed photovoltaics and EVs, are modeled explicitly in both transmission and distribution simulators for frequency and voltage dynamics, respectively. The case studies simulate the frequency responses (i.e., primary and/or secondary) of the EVs after the system is exposed to an N-1 contingency, such as a generation trip. Various EV frequency regulation participation strategies are also investigated to study their impacts on system frequency response. The studies shows that EVs have the potential capability to provide effective frequency regulation services.
- Cyber-Physical Dynamic System (CPDS) Modeling for Frequency Regulation and AGC Services of Distributed Energy ResourcesWenbo Wang, Xin Fang, Hantao Cui, and 6 more authorsAug 2022
The substantial integration of renewable energy brings significant challenges to balance the system in real time because of the variability and intermittency of renewable power. For the reliable system operation, the frequency regulation service is used to stabilize the system frequency through automatically balancing the system generation and load. On one hand, with the substantially increasing deployment of renewable energy in electricity system, the requirement of frequency regulation (FR) services increases significantly. On the other hand, the current main resource of FR services, the controllable conventional generation, is continuously decreasing in the system generation mix. This means that in the future high renewable penetration power system, additional and alternative reliable FR services providers such as distributed energy storage (DES) resources should be explored. Although the capability of utility-scale energy storage to provide FR services has been demonstrated, the integrated control and dynamic modeling of distributed energy resource (DER) providing frequency regulation grid services has been rarely explored. There are several challenges to adopt DERs to provide reliable grid services as illustrated in FERC 755. First, the distributed installation of DES requires a comprehensive cyber-physical dynamic system (CPDS) modeling to fully consider the impacts of the communication latency variability on its real time FR provision capability. Unlike the conventional generators, there are two-layer communication between DERs and system operators which increase the communication delay. Second, unlike the conventional generators whose dynamic models have been comprehensively studied, the difference among individual DER components’ power-dynamic characteristic brings challenges in the accurate dynamic AGC modeling of its power-frequency relationship. Third, the temporal dependent state of charge uncertainty of DERs challenges DERs’ power and frequency regulation capacities scheduling in the look-ahead generation scheduling. Therefore, the aggregator should optimize the frequency regulation provision from individual DER in real time. To overcome these challenges, this project proposes a cyber-physical dynamic system (CPDS) model to handle the uncertainty of DERs two-layer communication latency and power dynamics. The variability of DERs’ communication delay and dynamic constraints will be comprehensively modeled. The DERs’ AGC model with communication delay is designed to validate DESs’ frequency regulation services. Like current performance-based frequency regulation evaluation, the delivery of DERs’ frequency regulation will be assessed through post-analysis of the actual AGC response with respect to the AGC control signal from system operators. Consequently, the reliability improvement with DERs providing reliable frequency regulation services can be evaluated from a comprehensive perspective considering all the dynamics of communication and power.
- Electricity consumption variation versus economic structure during COVID-19 on metropolitan statistical areas in the USJinning Wang, Fangxing Li, Hantao Cui, and 2 more authorsNature Communications, Nov 2022
The outbreak of novel coronavirus disease (COVID-19) has resulted in changes in productivity and daily life patterns, and as a result electricity consumption (EC) has also shifted. In this paper, we construct estimates of EC changes at the metropolitan level across the continental U.S., including total EC and residential EC during the initial two months of the pandemic. The total and residential data on the state level were broken down into the county level, and then metropolitan level EC estimates were aggregated from the counties included in each metropolitan statistical area (MSA). This work shows that the reduction in total EC is related to the shares of certain industries in an MSA, whereas regardless of the incidence level or economic structure, the residential sector shows a trend of increasing EC across the continental U.S. Since the MSAs account for 86% of the total population and 87% of the total EC of the continental U.S., the analytical result in this paper can provide important guidelines for future social-economic crises.
- Profit-Oriented BESS Siting and Sizing in Deregulated Distribution SystemsXiaofei Wang, Fangxing Li, Qiwei Zhang, and 2 more authorsIEEE Transactions on Smart Grid, Nov 2022
Within the deregulation process of distribution systems, the distribution locational marginal price (DLMP) provides effective market signals for future unit investment. In that context, this paper proposes a two-stage stochastic bilevel programming (TS-SBP) model for investors to best allocate battery energy storage systems (BESSs). The first stage obtains the optimal siting and sizing of BESSs on a limited budget. The second stage, a bilevel BESS arbitrage model, maximizes the arbitrage revenue in the upper level and clears the distribution market in the lower level. Karush-Kuhn-Tucker (KKT) optimality conditions, strong duality theory, and the big-M method are utilized to transform the TS-SBP model into a tractable two-stage stochastic mixed-integer linear programming (TS-SMILP) model. A novel statistics-based scenario extraction algorithm is proposed to generate a series of typical operating scenarios. Then, scale reduction strategies for BESS candidate buses and inactive voltage constraints are proposed to reduce the scale of the TS-SMILP model. Finally, case studies on the IEEE 33-bus and 123-bus systems validate the effectiveness of the DLMP in incentivizing BESS planning and the efficiency of the two proposed scale reduction strategies.
2021
- Impacts of VSG Control on Frequency Response in Power Systems with High-Penetration RenewablesJinning Wang, Fangxing Li, Hantao Cui, and 1 more authorIn 2021 IEEE 5th Conference on Energy Internet and Energy System Integration (EI2), Oct 2021
With the increase of renewable energy into power systems, the system inertia continuously decreases, which poses challenges to the existing frequency regulating strategy. To improve system frequency response in the low-inertia system, Virtual Synchronous Generator (VSG) has been proposed in the literature. This paper investigates the VSG frequency response model and verifies the implementation at large scale. First, the frequency response model of VSC is investigated. In addition, the frequency response performance of the conventional synchronous generator (SG), the renewable power plant, and the renewable power plant with VSG are compared under different penetration levels of renewable energy. The simulation results show the capability of the CURENT Large-scale Testbed (LTB) for real-world, large-scale power system simulation in future scenarios and indicate that VSG-configured renewable power plants can provide the power grid with adequate frequency regulation ability under high renewable energy penetration.