Pilot Protection Method for DC Distribution Networks Based on Transient Voltage Cosine Similarity of Current-Limiting Reactor
When a short circuit or grounding fault occurs in a DC distribution network,its fault characteristics are complex,and a fast and reliable fault protection method is the key to ensuring the safe operation of the DC distribution network.A fast and reliable fault protection method is an important guarantee for the safe operation of DC distribution networks.A DC distribution network pilot protection method is proposed based on the cosine similarity of the transient voltage of the current-limiting reactor.Firstly,the differ-ences in the voltage characteristics of current-limiting reactors at both ends of the DC line are analyzed when a single line-to-ground or line-to-line faults occur inside and outside the DC distribution network,and according to the principle of cosine similarity,a fault discrimination method based on the cosine similarity of transient voltages of current-limiting reactors is proposed for the fast identification of internal/external DC fault.Then,the voltage surge ratio between the positive and negative poles of the current-limiting reactor is used to identify the type and polarity of DC faults,based on which corresponding protective measures are taken.Finally,a simulation model of a multi-terminal radiated DC distribution network is built using PSCAD/EMTDC simulation software.The effectiveness of the proposed protection method is verified.The simulation results show that the method has a certain degree of resistance to fault resistance and can better meet the rapidity and selectivity requirements of DC distribution network protection.
DC distribution networkcurrent limiting reactorfault protectionline-to-line faultsingle line-to-ground
万方数据
维普
