Abstract
When a short circuit fault occurs on the DC side line, the fault current reaches the peak within a few milliseconds, and the voltage drops significantly. This phenomenon can cause overcurrent flowing through the DC line, semiconductor devices, and AC side, which is a major threat to the operation of the entire system. To solve this problem, this paper proposes a fault location scheme based on parameter identification. Firstly, the entire DC distribution system is regarded as a graph. The intersections of the distribution system lines are regarded as vertices. The current flow of each line is regarded as a directed edge. The network topology matrix is constructed and a fault type recognition algorithm is proposed based on graph theory. Secondly, the mathematical model of the pole-to-pole short-circuit fault and pole-to-ground short-circuit fault are analyzed with double-ended electrical quantities. Transform the fault location problem into a parameter identification problem, four parameters to be identified are extracted, and the fitness function is constructed separately for two kinds of fault cases. Thirdly, a genetic algorithm (GA) is adopted to identify the value of parameters. Considering the fault types, transition resistance and fault location, the Matlab/Simulink simulation platform is used to simulate 18 fault conditions. The simulation results show that the positioning error of the fault location method is less than 1%, which is not affected by the transition resistance and has strong robustness.
Highlights
In recent years, the rapid increase of distributed power sources, such as wind power and solar power, has prompted the development of flexible DC distribution networks [1,2] which are based on voltage source converters (VSCs)
Since the process of a short-circuit fault on the DC side is transient, the DC circuit breaker cannot cut off the fault directly and quickly, which results in a greater threat to the entire DC system [4]
Considering that the probability and the degree of harm of disconnection fault are small, this paper mainly investigates investigates fault fault location location methods methods for for pole-to-pole pole‐to‐pole short-circuit short‐circuit faults faults and and pole-to-ground pole‐to‐ground mainly short‐circuit faults
Summary
The rapid increase of distributed power sources, such as wind power and solar power, has prompted the development of flexible DC distribution networks [1,2] which are based on voltage source converters (VSCs). Aiming at the deficiencies of the traveling wave method, an improved electromagnetic time-reversal (EMTR)-based method is proposed for fault-location in VSC multi-terminal high-voltage direct current system (VSC-MTDC) transmission lines [12]. This method has good performance when dealing with high impedance and failure of different types of DC lines. The literature [14] proposes a fault location method for DC lines based on a non-traveling wave principle, which only adopts single terminal electric quantity to realize the fault location. Proposed a non-traveling wave principle and this fault location method only uses the single-ended electric quantity of DC lines. The simulation on Matlab/Simulink platform verifies the positioning method
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