Parameter Optimization of MOSA for MVDC Circuit Breakers Based on Required Performance Using Short-Circuit Current Test-Bed Simulation

Abstract

Medium Voltage Direct Current (MVDC) systems are increasingly connected with renewable energy sources and DC loads for more flexible and efficient power transmission. Stable operation requires minimizing fault impacts and rapid fault isolation. This necessitates effective protection strategies, including fast-acting MVDC circuit breakers with optimized characteristics like fast fault detection, current zero-crossing mechanisms, high dielectric strength, and large energy absorption capability. The absorption energy of Metal Oxide Surge Arresters (MOSAs) in MVDC circuit breakers is influenced by system cable characteristics and increased when reactors are used to limit fault currents, requiring optimization. This paper presents a shortcircuit current test-bed using a low-frequency AC source to optimize MOSA for MVDC circuit breakers. Simulations in PSCAD/EMTDC were performed for 21 kV/1 MJ and 42 kV/2 MJ cases, analyzing MOSA absorption energy.