Comparison of short-circuit ratios of converter control for high-voltage DC power transmission systems

Abstract

Renewable energy (RE) is being rapidly introduced for decarbonization, and research on high-voltage direct current (HVDC) transmission for offshore wind power generation over long distances and high efficiency is highly expected. On the other hand, in the onshore AC power transmission and distribution system, there are problems such as voltage and frequency fluctuations due to the mass introduction of distributed energy resources (DERs). The movement to install the control function of smart inverters, which contribute to the stabilization of the AC system, in the grid-connected inverters of DERs is accelerating. Virtual synchronous generator (VSG) control is one of the smart inverter controls expected to contribute to the stabilization of the AC system. Therefore, in this study, conventional power control and VSG control are applied to the control of the modular multi-level converter (MMC)-based poles of the HVDC transmission system, and the AC/DC system fault tolerances of the entire system with various short circuit ratios (SCRs) are reported.