可控避雷器晶闸管阀串联均压方法

Voltage Sharing Method for Series-Connected Thyristor Valves of Controllable Metal Oxide Arrester

可控避雷器晶闸管阀主要由反并联晶闸管对串联而成,为保证各个晶闸管承受电压的一致性,必须采取适当的均压措施。根据晶闸管阀串联均压的技术要求,利用电力电子系统设计程序,对传统RC均压方法的可行性进行了计算分析。研究得出RC均压方法可能严重破坏可控避雷器的静态电位分布,不适用于晶闸管阀。提出采用晶闸管与金属氧化物电阻片一对一并联的均压方法,利用金属氧化物电阻片良好的非线性伏安特性限制晶闸管的过电压,并对电阻片的均压效果进行了仿真计算。结果表明,合理选择电阻片的串、并联数和尺寸参数,可以将串联晶闸管的开通过冲电压均限制在要求的范围内。

Thyristor valve of the controllable metal oxide arrester （CMOA） was mainly composed of series-connected inverse parallel thyristor pairs. To ensure the consistency of withstanding voltages of all thyristors, it was necessary to take proper measure of voltage sharing. According to technical requirements of voltage sharing for series-connected thyristor valves and using design program for power electronic system, the feasibility of traditional RC voltage sharing method was calculated and analyzed, and analysis results showed that in view of the fact that the static state potential distribution of CMOA might be seriously affected by RC voltage sharing, therefore it was inapplicable to thyristor valves. A new voltage sharing measure for CMOA was proposed： by means of adopting the voltage sharing method based on one-to-one parallel connection of thyristor with metal oxide resistor （MOR） the overvoltage of thyristors could be effectively restricted by the good nonlinear VA characteristic of MOR. The voltage sharing effect of MOR was simulated, and simulation results showed that as long as reasonably choosing the number of parallel-connected MOA and the number of series-connected MOA as well as the parameters of MOA size, the open voltage of thyristor could be restricted within the required region.