基于改进电容模型的直流开关振荡回路参数计算方法

Calculation Method of DC Switch Oscillation Loop Parameters Based on Improved Capacitance Model

特高压直流开关在特高压直流输电工程中是不可或缺的一次主设备,它的运行状况直接影响到直流输电系统的安全可靠运行,直流断路器在交流断路器的基础上还增加了振荡、吸能回路,使得它的结构更加复杂。直流开关中的振荡回路提供振荡电流来供开断,对其研究具有重要意义。为了实时准确地获取直流开关的运行状态和各项参数指标,提出了改进的直流开关振荡回路参数计算方法。该方法采用改进电容模型、高频采样,利用程序提取出电流的正负峰值点,采用最小二乘法,不断利用相邻2个正(负)峰值点数据求出振荡回路参数RLC值。以±1100 kV某换流站GRTS数据为例,通过与传统峰值点计算法比较,得出本文方法可将误差减小至3%以内,实验结果充分证明了计算方法的精确性与可行性。

UHV DC switch is an indispensable primary equipment in UHV DC transmission project. Its operating condition directly affects the safe and reliable operation of HVDC transmission system. DC circuit breaker also increases oscillation on the basis of AC circuit breaker. The energy absorption loop makes its structure more complicated. The oscillating circuit in the DC switch provides oscillating current for breaking,w hich is of great significance for its research. In order to accurately obtain the operating state and various parameter indexes of the DC switch in real time,an improved calculation method of DC switch oscillation circuit parameters is proposed. The method adopts the improved capacitance model and high-frequency sampling,and uses the program to extract the positive and negative peak points of the current. Using the least squares method,the adjacent two positive( negative) peak point data are continuously used to obtain the oscillation circuit parameter RLC value.Taking certain ±1100kV station GRTS data as an example, compared with the traditional peak point calculation method,it is concluded that the method can reduce the error to less than 3%. The experimental results fully prove the accuracy and feasibility of the calculation method.