某核电厂中压系统母线进线PT改造分析

PT of Incoming Busbar Transform Analysis in One Nuclear Power Plant

某核电6.6 kV中压系统母线进线PT初始设计存在不足,进线PT设置在进线柜下方的电缆室内。大修结束后,主变复役时发生PT断相、瞬发等故障,受中压开关柜"五防"功能限制,检修故障时必须将主变、厂变停役,严重影响机组的安全稳定运行。针对此类故障问题,分析了故障发生的原因,为提高设备运行的可靠性,指出了对进线PT实施改造的必要性。采用中置式PT柜取代现有进线PT的功能,消除了进线PT手车发生控制线插头松动,触头变形等故障,同时避免了机组在功率运行工况下,进线PT手车发生故障需要检修时必须先将反应堆停堆的先决条件。为适应新的运行方式,对进线柜的机械钥匙联锁进行了优化。分析并研究了改造方案,对比分析了改造前后设备结构。

The original design of 6.6kV incoming busbar PT deficiencies,PT for incoming line is installed in the cable room under the entry cabinet,in one nuclear power plant.After the overhauls,as the main transformer restoration,loss of phase and coefficient of PT are happened,under the"five prevention"function limit of the medium voltage switchgear,the main transformer and substation transformer must be stopped when the PT maintenance,seriously affect the safe and stable operation of the unit.In view of this kind of failure problem,the cause of the malfunction is analyzed.In order to improve the reliability of equipment operation,the necessity of carrying out the transformation of incoming busbar PT is pointed out.Using the function of middle mounted PT cabinet to replace the PT for incoming busbar,eliminates control line loose plug and contact deformation of PT truck.While avoiding reactor shutdown as a prerequisite,when the incoming PT truck maintenance,during the power operation.In order to adapt the new operation mode,the mechanical key interlocking of the incoming cabinet is optimized.This paper analyzes and studies the modification plan,compares and analyzes the equipment structure before and after the transformation.