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第篇电力系统过电压与绝缘配合.ppt

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电电气气信信息息学学院院SEEISEEISchool of Electrical Engineering and InformationSchool of Electrical Engineering and Information Sichuan University 线路和绕组的波过程电电气气信信息息学学院院SEEISEEISchool of Electrical Engineering and InformationSchool of Electrical Engineering and Information Sichuan University 过电压的概念超过额定的最高运行电压称为过电压过电压大气过电压内部过电压直击雷过电压感应雷过电压操作过电压谐振过电压电电气气信信息息学学院院SEEISEEISchool of Electrical Engineering and InformationSchool of Electrical Engineering and Information Sichuan University 一.波沿均匀无损单导线的传播1.什么是波过程电力系统中的电力系统中的过电压过电压绝大多数发源于绝大多数发源于输电线路输电线路，在发生雷，在发生雷击或进行操作时，线路上部可能产生以击或进行操作时，线路上部可能产生以行波形式行波形式出现的过电压出现的过电压波。

波在研究输电线路波过程时，如果从电磁场方程组出发，将在研究输电线路波过程时，如果从电磁场方程组出发，将是比较繁复的，为了方便起见，一般都采用以积分量是比较繁复的，为了方便起见，一般都采用以积分量u和和i表示表示的关系式的关系式不过这时不能象在工频电源和线路不长的情况下那样，用不过这时不能象在工频电源和线路不长的情况下那样，用某些某些集中参数等值电路集中参数等值电路来表示输电线路，来表示输电线路，而是必须用分布参数而是必须用分布参数电路和行波理论来进行分析电路和行波理论来进行分析这是因为过电压波的变化速度很这是因为过电压波的变化速度很快、延续时间很短快、延续时间很短电电气气信信息息学学院院SEEISEEISchool of Electrical Engineering and InformationSchool of Electrical Engineering and Information Sichuan University 电电气气信信息息学学院院SEEISEEISchool of Electrical Engineering and InformationSchool of Electrical Engineering and Information Sichuan University 2.波是怎样沿着导线传布的电电气气信信息息学学院院SEEISEEISchool of Electrical Engineering and InformationSchool of Electrical Engineering and Information Sichuan University 3.波阻抗电电气气信信息息学学院院SEEISEEISchool of Electrical Engineering and InformationSchool of Electrical Engineering and Information Sichuan University 4.波速电电气气信信息息学学院院SEEISEEISchool of Electrical Engineering and InformationSchool of Electrical Engineering and Information Sichuan University 二.波动方程线路上点在时间的电压和电流的波动方程电电气气信信息息学学院院SEEISEEISchool of Electrical Engineering and InformationSchool of Electrical Engineering and Information Sichuan University 电电气气信信息息学学院院SEEISEEISchool of Electrical Engineering and InformationSchool of Electrical Engineering and Information Sichuan University 波动方程的通解电电气气信信息息学学院院SEEISEEISchool of Electrical Engineering and InformationSchool of Electrical Engineering and Information Sichuan University 1.波动方程通解的物理意义(1).电压和电流均有两个部分组成：前行波和反行波电电气气信信息息学学院院SEEISEEISchool of Electrical Engineering and InformationSchool of Electrical Engineering and Information Sichuan University (2).电压与电流的方向的规定电电气气信信息息学学院院SEEISEEISchool of Electrical Engineering and InformationSchool of Electrical Engineering and Information Sichuan University (3).关于波阻抗的特点电电气气信信息息学学院院SEEISEEISchool of Electrical Engineering and InformationSchool of Electrical Engineering and Information Sichuan University a.表示同一方向电压波与电流波大小的比值，电磁波通过Z时，以电磁波的形式储存在周围介质中；b.导线上既有前行波又有反行波时，Z≠U/Ic. Z的数值与线路长度无关电电气气信信息息学学院院SEEISEEISchool of Electrical Engineering and InformationSchool of Electrical Engineering and Information Sichuan University 三.行波的折射与反射1.折射与反射电电气气信信息息学学院院SEEISEEISchool of Electrical Engineering and InformationSchool of Electrical Engineering and Information Sichuan University (1) 折射波与反射波电压波折射系数电电气气信信息息学学院院SEEISEEISchool of Electrical Engineering and InformationSchool of Electrical Engineering and Information Sichuan University 电压波反射系数与之间的关系电电气气信信息息学学院院SEEISEEISchool of Electrical Engineering and InformationSchool of Electrical Engineering and Information Sichuan University (2) 几种特殊条件下的折、反射波a. 线路末端开路电电气气信信息息学学院院SEEISEEISchool of Electrical Engineering and InformationSchool of Electrical Engineering and Information Sichuan University b. 线路末端短路电电气气信信息息学学院院SEEISEEISchool of Electrical Engineering and InformationSchool of Electrical Engineering and Information Sichuan University c. 线路末端接负截电阻R电电气气信信息息学学院院SEEISEEISchool of Electrical Engineering and InformationSchool of Electrical Engineering and Information Sichuan University 2. 彼德逊法则电电气气信信息息学学院院SEEISEEISchool of Electrical Engineering and InformationSchool of Electrical Engineering and Information Sichuan University 要计算分布参数线路上节点的电压可用集中参数等值电路计算：a.线路波阻抗用数值相等的集中参数等值电阻代替b.把线路上的入射电压波的两倍作为等值电压源电电气气信信息息学学院院SEEISEEISchool of Electrical Engineering and InformationSchool of Electrical Engineering and Information Sichuan University 例题一变电所母线上接有n 条线路，每条线路波阻抗为Z，当一条线路落雷，电压u(t)入侵变电所，求母线上电压。

电电气气信信息息学学院院SEEISEEISchool of Electrical Engineering and InformationSchool of Electrical Engineering and Information Sichuan University 四. 行波通过串联电感和并联电容1. 通过串联电感电电气气信信息息学学院院SEEISEEISchool of Electrical Engineering and InformationSchool of Electrical Engineering and Information Sichuan University 回路方程：解得：电电气气信信息息学学院院SEEISEEISchool of Electrical Engineering and InformationSchool of Electrical Engineering and Information Sichuan University 于是：它有二个部分组成：一部分是与时间无关的强制分量；另一部分为随时间而衰减的自由分量电电气气信信息息学学院院SEEISEEISchool of Electrical Engineering and InformationSchool of Electrical Engineering and Information Sichuan University 当 t=0 时时电电气气信信息息学学院院SEEISEEISchool of Electrical Engineering and InformationSchool of Electrical Engineering and Information Sichuan University 通过电感后折射波的陡度：最大陡度出现在t=0时：最大空间陡度：电电气气信信息息学学院院SEEISEEISchool of Electrical Engineering and InformationSchool of Electrical Engineering and Information Sichuan University 折射波电压、电流随时间变化电电气气信信息息学学院院SEEISEEISchool of Electrical Engineering and InformationSchool of Electrical Engineering and Information Sichuan University 在A点反射波电压和电流因为可得电电气气信信息息学学院院SEEISEEISchool of Electrical Engineering and InformationSchool of Electrical Engineering and Information Sichuan University 当t=0 此时波到达电感瞬间，圈首端的电压将上升到入射波电压两倍电电气气信信息息学学院院SEEISEEISchool of Electrical Engineering and InformationSchool of Electrical Engineering and Information Sichuan University 当t→∞此时时间很长以后，达到稳定值电电气气信信息息学学院院SEEISEEISchool of Electrical Engineering and InformationSchool of Electrical Engineering and Information Sichuan University 反射波电流t=0t→∞电电气气信信息息学学院院SEEISEEISchool of Electrical Engineering and InformationSchool of Electrical Engineering and Information Sichuan University 反射波电压、电流随时间变化电电气气信信息息学学院院SEEISEEISchool of Electrical Engineering and InformationSchool of Electrical Engineering and Information Sichuan University 2.通过并联电容电电气气信信息息学学院院SEEISEEISchool of Electrical Engineering and InformationSchool of Electrical Engineering and Information Sichuan University 回路方程电电气气信信息息学学院院SEEISEEISchool of Electrical Engineering and InformationSchool of Electrical Engineering and Information Sichuan University 解得：电电气气信信息息学学院院SEEISEEISchool of Electrical Engineering and InformationSchool of Electrical Engineering and Information Sichuan University 当t=0时：时：电电气气信信息息学学院院SEEISEEISchool of Electrical Engineering and InformationSchool of Electrical Engineering and Information Sichuan University 经过并联电容时，折射波的陡度：最大陡度出现在t=0时：最大空间陡度：电电气气信信息息学学院院SEEISEEISchool of Electrical Engineering and InformationSchool of Electrical Engineering and Information Sichuan University 折射波电压、电流随时间变化电电气气信信息息学学院院SEEISEEISchool of Electrical Engineering and InformationSchool of Electrical Engineering and Information Sichuan University 反射波电压、电流电电气气信信息息学学院院SEEISEEISchool of Electrical Engineering and InformationSchool of Electrical Engineering and Information Sichuan University 当t=0时电电气气信信息息学学院院SEEISEEISchool of Electrical Engineering and InformationSchool of Electrical Engineering and Information Sichuan University 当t→∞时电电气气信信息息学学院院SEEISEEISchool of Electrical Engineering and InformationSchool of Electrical Engineering and Information Sichuan University 反射波电压、电流随时间变化电电气气信信息息学学院院SEEISEEISchool of Electrical Engineering and InformationSchool of Electrical Engineering and Information Sichuan University 例题：假定发电机的波阻抗为800 ，如果电机前面与电缆相接，电缆波阻抗为50 ，波在电机内的传播速度为，其匝间耐压为600V，每匝长度为3m。

若沿电缆有100kV的无限长直角波入侵，求为保护发电机匝间绝缘所需串联的电感或并联的电容的数值电电气气信信息息学学院院SEEISEEISchool of Electrical Engineering and InformationSchool of Electrical Engineering and Information Sichuan University 五.行波的多次折、反射1.用网格法计算波的折、反射电电气气信信息息学学院院SEEISEEISchool of Electrical Engineering and InformationSchool of Electrical Engineering and Information Sichuan University 电电气气信信息息学学院院SEEISEEISchool of Electrical Engineering and InformationSchool of Electrical Engineering and Information Sichuan University 电电气气信信息息学学院院SEEISEEISchool of Electrical Engineering and InformationSchool of Electrical Engineering and Information Sichuan University 电电气气信信息息学学院院SEEISEEISchool of Electrical Engineering and InformationSchool of Electrical Engineering and Information Sichuan University 2.串联三导线典型参数配合时波过程的特点(1).电电气气信信息息学学院院SEEISEEISchool of Electrical Engineering and InformationSchool of Electrical Engineering and Information Sichuan University (2).电电气气信信息息学学院院SEEISEEISchool of Electrical Engineering and InformationSchool of Electrical Engineering and Information Sichuan University (3).电电气气信信息息学学院院SEEISEEISchool of Electrical Engineering and InformationSchool of Electrical Engineering and Information Sichuan University (4).电电气气信信息息学学院院SEEISEEISchool of Electrical Engineering and InformationSchool of Electrical Engineering and Information Sichuan University 六.行波在平行多导线系统中的传播1.多导线系统的电压、电流方程电电气气信信息息学学院院SEEISEEISchool of Electrical Engineering and InformationSchool of Electrical Engineering and Information Sichuan University 自电位系数电电气气信信息息学学院院SEEISEEISchool of Electrical Engineering and InformationSchool of Electrical Engineering and Information Sichuan University 互电位系数电电气气信信息息学学院院SEEISEEISchool of Electrical Engineering and InformationSchool of Electrical Engineering and Information Sichuan University 自波阻抗电电气气信信息息学学院院SEEISEEISchool of Electrical Engineering and InformationSchool of Electrical Engineering and Information Sichuan University 互波阻抗电电气气信信息息学学院院SEEISEEISchool of Electrical Engineering and InformationSchool of Electrical Engineering and Information Sichuan University 2. 耦合系数k(1) 两导线系统电电气气信信息息学学院院SEEISEEISchool of Electrical Engineering and InformationSchool of Electrical Engineering and Information Sichuan University 电电气气信信息息学学院院SEEISEEISchool of Electrical Engineering and InformationSchool of Electrical Engineering and Information Sichuan University 感应电压的若干特点： (1)由于正、负电荷只是在导线2上作横向的分离，所以可瞬时完成；同样地，当消失时，正、负电荷立即就地中和，同样不需要时间，所以与同步推进、同生同灭。

(2) 的极性一定与相同 (3) 与的波形相似．但—定小于( ＜1)返回返回电电气气信信息息学学院院SEEISEEISchool of Electrical Engineering and InformationSchool of Electrical Engineering and Information Sichuan University (2) 多导线系统电电气气信信息息学学院院SEEISEEISchool of Electrical Engineering and InformationSchool of Electrical Engineering and Information Sichuan University 七.线路上行波的衰减和变形1.冲击电晕的形成和特点电电气气信信息息学学院院SEEISEEISchool of Electrical Engineering and InformationSchool of Electrical Engineering and Information Sichuan University 2.电晕对导线上波过程的影响(1)使导线的耦合系数增大(2) 使导线的波阻抗和波速减小(3)使波在传播过程中幅值衰减，波形畸变电电气气信信息息学学院院SEEISEEISchool of Electrical Engineering and InformationSchool of Electrical Engineering and Information Sichuan University 电电气气信信息息学学院院SEEISEEISchool of Electrical Engineering and InformationSchool of Electrical Engineering and Information Sichuan University 八.变压器绕组中的波过程1.简化等值电路电电气气信信息息学学院院SEEISEEISchool of Electrical Engineering and InformationSchool of Electrical Engineering and Information Sichuan University 2.绕组中初始电压分布(1).绕组末端接地电电气气信信息息学学院院SEEISEEISchool of Electrical Engineering and InformationSchool of Electrical Engineering and Information Sichuan University 电电气气信信息息学学院院SEEISEEISchool of Electrical Engineering and InformationSchool of Electrical Engineering and Information Sichuan University 电电气气信信息息学学院院SEEISEEISchool of Electrical Engineering and InformationSchool of Electrical Engineering and Information Sichuan University (2).绕组末端开路绕组首端处：u=U0绕组末端处：电电气气信信息息学学院院SEEISEEISchool of Electrical Engineering and InformationSchool of Electrical Engineering and Information Sichuan University 电电气气信信息息学学院院SEEISEEISchool of Electrical Engineering and InformationSchool of Electrical Engineering and Information Sichuan University (3).变压器的入口电容电电气气信信息息学学院院SEEISEEISchool of Electrical Engineering and InformationSchool of Electrical Engineering and Information Sichuan University 3.绕组中的稳态电压分布(1).绕组末端接地电电气气信信息息学学院院SEEISEEISchool of Electrical Engineering and InformationSchool of Electrical Engineering and Information Sichuan University (2).绕组末端开路电电气气信信息息学学院院SEEISEEISchool of Electrical Engineering and InformationSchool of Electrical Engineering and Information Sichuan University 电电气气信信息息学学院院SEEISEEISchool of Electrical Engineering and InformationSchool of Electrical Engineering and Information Sichuan University 4. 三相绕组中的波过程(1).中性点接地的星形接线电电气气信信息息学学院院SEEISEEISchool of Electrical Engineering and InformationSchool of Electrical Engineering and Information Sichuan University (2).中性点不接地的星形接线电电气气信信息息学学院院SEEISEEISchool of Electrical Engineering and InformationSchool of Electrical Engineering and Information Sichuan University 电电气气信信息息学学院院SEEISEEISchool of Electrical Engineering and InformationSchool of Electrical Engineering and Information Sichuan University (3).三角形接线电电气气信信息息学学院院SEEISEEISchool of Electrical Engineering and InformationSchool of Electrical Engineering and Information Sichuan University 三相同时进波电电气气信信息息学学院院SEEISEEISchool of Electrical Engineering and InformationSchool of Electrical Engineering and Information Sichuan University 电电气气信信息息学学院院SEEISEEISchool of Electrical Engineering and InformationSchool of Electrical Engineering and Information Sichuan University 5.冲击电压在绕组间的传递。

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