535kV耦合负压式直流断路器短路电流开断试验研究

Research on Short-circuit Current Breaking Test of 535 kV DC Circuit Breakers Based on Coupled Negative Voltage Commutation

直流断路器是柔性直流电网的关键设备,肩负着数毫秒内切除故障设备或线路的作用,短路电流开断试验用于考核直流断路器开断故障电流的能力,是直流断路器型式试验的核心。该文基于张北±500k V柔性直流输电工程,首先阐述了耦合负压式直流断路器的主要技术参数及工作原理,然后详细介绍了短路电流开断试验要求以及试验方法,并基于交流单频振荡法搭建了试验平台,试验平台主要包括直流充电电源、电容器塔、电抗器、放电电阻以及各种开关等设备。试验结果表明:该试验平台能够满足短路电流开断试验要求,以535 kV耦合负压式直流断路器为试品,完成了7.5 kA、15 kA和25 kA短路电流开断试验,从直流断路器接到分闸指令至试验回路电流开始下降的时间均小于3 ms,开断时直流断路器端间过电压峰值均未超过800 kV,满足直流断路器设计要求,可为直流断路器短路电流开断试验提供参考依据。

DC circuit breaker,which is responsible for cutting off faulty equipment or line within several milliseconds,is a key device in flexible DC grid.The short-circuit current breaking test,which is used to evaluate the ability of DC circuit breaker to cut off fault current,is the core of type test of DC circuit breaker.Based on Zhangbei±500 kV flexible HVDC transmission project,firstly,the main parameters and working principle of the coupled negative-voltage DC circuit breaker are introduced in this paper.Furthermore,the requirements and the method of the short-circuit current breaking test are expounded in detail,and a test platform based on AC single frequency oscillation is built accordingly.The test platform mainly consists of DC charging power supply,capacitor tower,reactor,discharge resistors,and a series of switches.The test results show that the platform can meet the requirements of short-circuit current breaking test.The 535 kV DC circuit breaker has been tested with a referenced consequence of 7.5 kA,15 kA and 25 kA short-circuit current breaking.During each procedure,the time from the DC circuit breaker receiving the switching instruction to the beginning of current decline in the test circuit is less than 3 ms,and the peak overvoltage between the terminals of the DC circuit breaker does not exceed 800 kV when the DC circuit breaker is opening,which meets the design requirements of the DC circuit breaker and can provide a reference for the DC circuit breaker short-circuit current breaking test.