电力电容器地局部放电测量.ppt

* * Lecture 7 PD Detection in Power Capacitors 电力电容器的局部放电测量 Contents 1. Partial Discharge in Power Capacitors 电力电容器中的局部放电 2. Parameters and Standard 测试参数及相关规程 3. Electrical Detection of PD in Capacitor 电力电容器的局部放电电测法 1. Partial Discharge in Power Capacitors 1.1 the characteristics of power capacitors Insulation structure of capacitors: oil-impregnated papers, oil-impregnated dielectric membrane and their combination. 绝缘结构：油浸纸，浸渍薄膜及其组合 Extremely high electrical field stress exists in capacitors and partial discharges are very possible to occur inside. 介质工作场强特别高，内部特别容易发生局部放电 电力电容器的特点 1.2 Inception and damage of PD in power capacitor 1. Partial Discharge in Power Capacitors The lifetime of capacitor suffering from PD decreases exponentially. PD is a key factor that results in expanding and incipient fault of power capacitor. 在局部放电作用下，寿命是随着电场的增加而呈指数形式下降的 局部放电是造成电容器膨胀和早期损坏的一个重要因素 2. Parameters and Specification 2.1 Parameters to estimate the PD of capacitor Apparent charge, q Inception voltage, Ui The AC voltage across the capacitor at which the discharge magnitude exceeds a given value qg. 视在放电量 升压过程中，观测到的放电量超过某个规定值时的最低电压 Inception voltage (stress): The AC voltage (stress) across the sample at which discharges start to occur when the voltage is increased . Extinction voltage, Ue 降压过程中，观测到放电量低于某个规定值的最高电压值。 The AC voltage across the capacitor at which the discharge magnitude is less than the given magnitude qg. a is better than b 2. Parameters and Specification Change of q with voltage applying time 放电量随加压时间的变化 2.2 Procedure of PD detection 2. Parameters and Standards U1:pre-applied Voltage 预加电压 Type U1 (kV) U2 (kV) U3 (kV) Requirement Note Shunt capacitors 2.15 u n , 1s 1.2 u n , 10 min 1.5 u n , 10min Series - connected capacit ors 4. 5 u n , 1s 1.6 u n , 1 0 min Breaker capacitors 1.8 u n , 1s 1. 1 u n , 10 min D uring last 10 min , no PD impulses with increased magnitude are observed. u