Modeling and Simulation of ±10 kV DC Transmission System based on Mechanical DC Circuit Breaker

Abstract

In order to simulate the interruption process of mechanical DC circuit breaker in actual DC power grid and obtain various stress characteristics of DC circuit breaker in actual interruption process, it is necessary to establish a stable and effective flexible DC system model with good dynamic performance. In this paper, the controller models of system level, converter station level and converter valve level are established for the 10kV flexible DC system, and then the steady-state characteristics and dynamic characteristics of power step of the system are simulated. After analyzing the variation of voltage, current and power and dynamic response speed of converter station, the simulation results show that DC voltage and active power of the system operate stably according to the reference value and the fluctuation error of DC voltage is less than 1%. The internal and external loop controllers all track the dynamic changes of their respective command values rapidly within 0.5s. The control performance of the flexible DC system model can meet the requirement of the interruption simulation of DC circuit breakers.