Optimal Grid-Support Strategy With Inverter-Interfaced Distributed Generators for Short-Term Voltage Stability Improvement

With the increasing integration of renewable energy sources into distribution networks, short-term voltage stability (STVS) has become a prominent issue. Considering grid impedance and maximum rated current, a novel dynamic voltage support (DVS) control strategy for inverter-interfaced distributed generators (IIDGs) is proposed in this article for improving STVS. Furthermore, the impact mechanism of load dynamics and load spatial distribution on the STVS-support strategy are elucidated. For maximizing the STVS of the system, due to the difficulty of obtaining analytical closed-form expressions, a practical optimization method for multi-IIDG is proposed for the optimal control parameters. The optimization is solved alternately based on the time-domain simulation (TDS) and the simultaneous perturbation stochastic approximation (SPSA) algorithm. The STVS is evaluated by a proposed quantitative indicator. According to the operation state of the system, the control strategy can be adjusted online. The effectiveness of the proposed method is verified based on two test systems. Compared with other DVS capabilities, the STVS is further improved by considering distributed dynamic loads. The applicability and computational efficiency of the proposed method are discussed under various key conditions.