Cyber Stability Region of Power System with Distributed EV Integration

This paper investigates the stability of a power system with distributed EV integration embedded by cyber delays in the cyber-physical system. An efficient stability region extraction method based on infinitesimal generator transformation is used to extract all stabilizing values in cyber delay space. We obtain the disrupted time-delay stability region for the power system with a single and double EV aggregators and investigate the interaction among the delay margins and PI controller gains. Verification of theoretical stability region boundaries is shown by time-domain simulations for test points selected from stability regions. Through the case study, it is revealed that with the integration of distributed EVs into the power system, there is no longer a definite time-delay stability margin like the traditional power system, but under some parameter settings, the system stability region is disrupted by several intervals and presents periodic changes. And the cyber delay in EV aggregator with the higher participation ratio has a smaller range of cyber delay region. Results also show that an increase in the integrator gain reduces the stability region, while the range of stability region in time-delay space increases and then decreases as increases, which introduces cyber stability challenges to traditional frequency dynamics. It is expected that the proposed criteria can help to guide the determination of delay requirements for EV aggregators participating in frequency regulation service.