Analysis of Short-Term Voltage Stability Influencing Factors and Mechanisms in Low Inertia Active Distribution Networks

Driven by the call for low-carbon operation of distribution networks, the penetration of renewable energy sources and dynamic loads keeps increasing, which also critically lowered the inertia of the whole system and stressed the short-term voltage stability (STVS) issue. Due to the high-order and nonlinear nature of the system nature, however, STVS is conventionally evaluated by a black-box model either via time-domain simulations or learning approaches. Hence, mathematical analytics are absent, thus making the investigation of STVS mechanism technically intractable to date. This paper attempts to investigate the mechanism of STVS in active distribution networks with respect to loading level, network structure and renewable energy generation. A procedure to identify the key influencing factors of STVS based on an attribution analysis model is proposed. And the impact and distribution of critical nodes on STVS are discovered. The analysis is verified via case studies on an IEEE standard benchmark.