可控避雷器的静态电位分布计算方法

Calculation Method for Voltage Distribution of Controlled Metal Oxide Arresters

可控避雷器的晶闸管开关中晶闸管的等效电容CT随端电压UT的变化而变化,在计算可控避雷器静态电位分布时,须考虑该特点。将"场路结合法"与CT随UT的变化规律相结合,提出了可控避雷器静态电位分布计算方法,即先建立受控元件、固定元件和晶闸管均压电阻的电场数值计算模型,求出等效杂散电容网络;再通过试验检测和曲线拟合,求出晶闸管CT和UT之间的函数关系;然后建立可控避雷器等效电路模型,将CT和UT之间的函数代入电路模型中,通过反复迭代,求得各电极电位UFi与避雷器端电压Us之间的函数;最后将UFi与Us之间的函数代入电场数值计算模型中,求出可控避雷器静态电位分布随Us的变化规律。经试验验证,该计算方法用于求解可控避雷器静态电位分布是有效的。

Equivalent capacitances of thyristors of thyristor switch in the controlled metal oxide arrester （CMOA）, CT, changes with voltage, UT. When the voltage distribution of CMOA is calculated, such characteristic should be fully considered. Combining field-circuit combination method and variation rule of CT with UT, a calculation program was put forward. Firstly, electromagnetic-field numerical calculation models of controlled component, fixed component and resistance of thyristor were established and an equivalent capacitance network was set up. Then the relation between CT and Ur, was solved by test and curve fitting. Secondly, an equivalent circuit of CMOA was founded, the relation between CT and UT was substituted to the circuit, then the function between the electrode voltage, UFi, and the CMOA voltage, Us could be calculated by iterations. Finally, the function between UFi and Us was substituted to the electromagnetic-field numerical calculation model, the variation rule of voltage distribution with Us was solved. The calculation program was verified by tests. Results indicated that it is effective to calculate the voltage distribution of CMOA.