Project Title: Cyber-Physical Dynamic System (CPDS) Modeling for Frequency Regulation and AGC Services of Distributed Energy Resources
Date: 1/2022 – 12/2022
Affiliation: University of Tennessee, Knoxville; NREL
Advisor: Fangxing Fran Li, Xin Fang (MSU), Wenbo Wang (NREL)
This project aims to develop an open-source, scalable, transmission, distribution, and communication, dynamic co-simulation framework to study the impacts of communication failures of distributed energy resources (DERs) providing frequency regulation services on electric power system stability.
As part of this project, Jinning focused on exploring the use of electric vehicles (EVs) to provide secondary frequency regulation services. By integrating EVs into the grid for this purpose, the project aims to address critical aspects of grid frequency stability.
The source paper of EV providing SFR can be found in [1], and the full project report can be found in [2].
More details can be found in the project homepage LTB.
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.
@article{wang_electric_2024,title={Electric {Vehicles} {Charging} {Time} {Constrained} {Deliverable} {Provision} of {Secondary} {Frequency} {Regulation}},issn={1949-3053, 1949-3061},url={https://ieeexplore.ieee.org/document/10411057/},doi={10.1109/TSG.2024.3356948},urldate={2024-01-23},journal={IEEE Transactions on Smart Grid},author={Wang, Jinning and Li, Fangxing and Fang, Xin and Wang, Wenbo and Cui, Hantao and Zhang, Qiwei and She, Buxin},year={2024},volume={15},number={4},pages={3892-3903},dimensions={true},}
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.
@techreport{wang_cyber-physical_2022,title={Cyber-{Physical} {Dynamic} {System} ({CPDS}) {Modeling} for {Frequency} {Regulation} and {AGC} {Services} of {Distributed} {Energy} {Resources}},url={https://www.osti.gov/servlets/purl/1882191/},language={en},number={NREL/TP-6A40-82644, 1882191, MainId:83417},urldate={2023-01-09},author={Wang, Wenbo and Fang, Xin and Cui, Hantao and Wang, Jinning and Li, Fangxing and Liu, Yijing and Overbye, Thomas and Cai, Mengmeng and Irwin, Chris},month=aug,year={2022},doi={10.2172/1882191},keywords={JWang},pages={NREL/TP--6A40--82644, 1882191, MainId:83417},dimensions={true},}
