Fault section locating method and recovery strategy of pole-to-ground fault for medium voltage direct current (MVDC) distribution network

Abstract

High-resistance clamping grounding is a common grounding mode of modular multilevel converter (MMC) based DC distribution network. Due to the current limiting function of grounding resistor, pole-to-ground fault can only cause limited steady-state fault current. Consequently, it is very difficult to locate fault section. Besides, there are a few research works on pole-to-ground fault recovery strategy of a DC distribution system. This study purposes a fault criterion based on DC pole-to-ground voltage amplitude and changing rate. Then, by extracting polarities of a DC feeder current travelling wave using the method of wavelet transform modulus maximum, a rapid fault section locating method is presented. Furthermore, a feasible pole-to-ground fault recovery strategy is introduced, which can reduce outage range and time on the premise of guaranteeing system stability. The performances of the proposed methodologies were validated by numerical simulation.

Keywords

• resistors
• fault currents
• power distribution faults
• power transmission faults
• power distribution protection
• fault location
• wavelet transforms
• distribution networks
• earthing
• common grounding mode
• MMC-based DC distribution network
• grounding resistor
• steady-state fault
• pole-to-ground fault recovery strategy
• DC distribution system
• fault criterion
• DC pole-to-ground voltage amplitude
• changing rate
• DC feeder current travelling wave
• rapid fault section locating method
• MVDC distribution network
• high-resistance clamping grounding