高低阀串联型特高压柔性直流不控整流异步充电时分压特性及其对系统的影响

Voltage Partial Characteristics of Uncontrolled Rectifier Asynchronous Charging and Its Influence on VSC-UHVDC System with High and Low Valves in Series

乌东德特高压多端混合直流输电工程是目前世界电压等级最高、容量最大的柔性直流输电工程,具备无闭锁直流故障穿越能力,然而该工程为全桥+半桥混连结构,不控整流异步充电时交流断路器未合闸的阀组全桥模块被动充电,阀组直流端口呈现感应电压,某些接线方式甚至出现感应电压过高而引起系统跳闸停运。针对异步充电问题,从几种主要接线方式分析了阀组异步充电的分压特性和感应充电对系统的影响,提出了通过直流短接充电隔离阀组的方法解决阀组分压的问题,并根据异步充电特性提出了缩短异步充电时间间隔的方法解决阀组分压的问题。

Wudongde hybrid multi-terminal UHVDC is nowadays the world's highest voltage and largest capacity flexible DC transmission project.It has the ability of non-blocking DC fault ride through.However,the project is a mixed structure of full bridge and half bridge.When the AC circuit breaker of uncontrolled rectifier asynchronous charging is not closed,the full bridge modules of the valve group are charged passively,and the DC port of the valve group presents induced voltage.In some connection modes,the induced voltages are very high,which cause the system to trip.Aiming at the problem of asynchronous charging,the partial voltage characteristics of valve group asynchronous charging from several main connection modes and the influence of induction charging on the system are analyzed.The method of isolating valve group by DC short circuit charging is proposed to solve the problem of valve group partial voltage,and according to the characteristics of asynchronous charging,the method of shortening asynchronous charging time interval is proposed to solve the problem of valve group partial voltage.