Fault detection and location in multi-terminal DC microgrid based on local measurement

Abstract

This paper presents a fault detection and location method for multi-terminal DC microgrid based on local measurement. Firstly, a new concept called pseudo voltage is defined and illustrated in this paper. In order to find out the conditions for distinguishing between internal and external faults, the line voltage characteristics after DC microgrid faults are analyzed. And then, the fault detection scheme based on pseudo voltage principle is proposed. Using only the local measurements, the scheme can realize the protection of the whole DC line without communication. Meanwhile, this paper also presents a fault location scheme, which adds an auxiliary capacitor to the inner side of DC circuit breaker. Considering the voltage and current of the capacitor, which is a function of the fault distance and the fault resistance, the fault location is obtained. A five-terminal ring-type DC microgrid model is employed as the test system. The results show that the proposed method can quickly detect the fault segment of the DC line and accurately locate the fault point.