Fault detection of AC distribution systems nearby VSC MVDC systems by combination of wavelet analysis and current index

Nowadays, the growth of AC distribution networks joined to DC transmission is increasing due to renewable energy sources and necessary requirements for conversion of sustainable energy to expendable energy in the main grid. This paper investigates impacts of medium voltage direct current system on transient states of AC distribution system integrated with it, consists of circuit breaker operation and faults. We propose a wavelet based approach for distinguishing between act of circuit breaker and faults and then obtaining the detection of faults. Simulation of a MW MVDC system that connected to AC distribution system is done. Types of different faults and circuit breaker reclosing occur in AC side near to invertor. Results show that while traditional protections are not sufficient for fault detection, proposed scheme is totally capable of protecting faults.