Examination of fast frequency response capacity requirements considering frequency ride-through capabilities in distributed generators with legacy inverters

Abstract

Given the rapid increase in inverter-based distributed generators (IBDGs), their response and subsequent impacts on power system stability during abnormal power system conditions are becoming important. Recent events have shown that an unexpected loss of IBDGs triggered by their outdated frequency ride-through (FRT) capability can occur, which in turn can lead to a power system frequency below the secure operation region. As FRT characteristics of IBDGs are dependent on their time of installation and capability to update FRT parameters, IBDGs with different ride-through characteristics are mixed within the power system. In this study, the potential impacts of FRT capabilities of IBDGs with legacy inverters have been investigated. The analysis was conducted considering the penetration level of IBDGs and complying with FRT characteristics. Furthermore, the required amount of fast frequency response resources, which are generally provided by battery energy storage systems, was evaluated along with the secure operating envelope that can aid in future power system planning. Case studies on modified New England 10-machine test system and Korean power system were conducted to validate the effectiveness of the analysis.