高压直流输电保护定值整定依据及配合关系探讨

Discussion on Basis and Coordination Relationships of Settings for High Voltage Direct Current Transmission Protection

在中国30余年的高压直流输电工程实践中形成了一套高压直流输电保护系统定值体系。文中结合近年来在应用中出现的复杂案例,对以下保护的定值整定依据开展了进一步探讨:阀短路保护启动定值需避开与换流阀并联的阻容回路的充电电流;换流器过流保护过负荷段定值整定依据是直流控制系统失控造成直流运行电流超过控制的过负荷目标值,以及控制目标电流超过所设定的运行时间;直流低电压保护阈值及延时定值的整定需兼顾保护的后备功能,不确保与换相失败保护双桥原理长延时段配合。另外,深入探讨了交直流系统间、金属回线运行方式下直流保护间,以及高压线路再启动与低压再启动间的定值配合问题。最后,提出了高压直流输电保护系统的定值及定值间的配合应有一定的规范性和适度的灵活性的建议。

A set of high voltage direct current(HVDC)protection system setting system has been established in the engineering practice of HVDC in China for more than 30 years.For the complicated cases in application in recent years,this paper discusses the setting basis for the following protections:the starting setting of valve short-circuit protection needs to avoid the charging current of the resistance-capacitance circuit in parallel with the converter valve.And the over-current protection over-load section of the converter aims at the over-load target value of the DC operation current caused by the control failures,and the control target current exceeding the set running time.The setting of DC low-voltage protection threshold and delay-time should take into account the backup function of protection,and can not match with the long delay time period of the double-bridge principle of commutation failure protection.In addition,in-depth discussions are conducted on the coordination problems of setting between AC and DC systems,between DC protections in metal-return operating mode,and between high-voltage line restart and low-voltage restart.Finally,it is suggested that the setting and coordination between the setting values of HVDC transmission protection system should have certain standardization and moderate flexibility.