摘要
提出了新的电网电容电流自动跟踪测量方法。当电网高度平衡时 ,连续调节消弧线圈电感 ,使中性点工频电压位移达到最大值 ,此时消弧线圈的感抗就等于电网的对地总容抗 ,由此计算出电容电流 ;当电网有一定的不平衡度时 ,将消弧线圈调至等效电感电流为I1,I2 ,I3 的位置 ,测得中性点位移电压U1,U2 ,U3 ,计算出系统电容电流 ,算式中考虑了电网阻尼率的影响 ,计算精度高。依据电感电流变化ΔIL 与电容电流反向变化ΔIC 造成的中性点电压变化量ΔU相等的原理 ,设定电容电流跟踪灵敏度。通过连续检测中性点位移电压的变化量 ,实现电容电流的自动跟踪测量。动态调谐方案是 :在电网正常运行时 ,跟踪检测电网电容电流 ;电网发生单相接地后 ,调谐消弧线圈实现全补偿。研制出基于上述原理的偏磁式消弧线圈控制器 ,给出了控制器的软、硬件框图及装置动态响应波形。实测表明该装置电容电流测量误差小于 3% ,动态补偿暂态过程小于
A new method of measurement for automatically tracing the capacitive current of power systems is proposed. When the grid is highly balanced and the inductance of arc-suppression coil is adjusted continuously, thus making the neutral voltage maximum in 50 Hz, the inductive reactance of arc-suppression coil is equal to the capacitive reactance of the grid-to-ground. In this way the capacitive current can be calculated. When the grid is not highly balanced, by adjusting inductive current of arc-suppression coil to I1, I2, I3, getting the neutral voltages U1, U2, U3, and then figuring out the capacitive current, the precision is higher as the damp rate is taken into account. The sensitivity of tracing capacitive current is determined by the principle that the added inductive current δIL or the inverse added capacitive current δIC produces the same added neutral voltage δU. The capacitive current can be traced automatically by measuring the added neutral voltage continuously. Furthermore, the dynamic resonance adjustment method is as follows: measuring capacitive current in real-time when the grid operates in normal, tuning arc-suppression coil and making it compensate for the capacitive current completely when single-phase-to-ground fault occurs. The controller of arc-suppression coil with magnetic bias, based on the principle above, has been developed. The block diagrams of its software and hardware and transient response waveforms are presented. It is shown that the error in measuring capacitive current is less than 3% and the transient process of compensation is less than two cycles.
出处
《电力系统自动化》
EI
CSCD
北大核心
2002年第15期53-56,69,共5页
Automation of Electric Power Systems
关键词
偏磁式消弧线圈
动态调谐装置
单片机
晶闸管
Computer simulation
Electronic circuit tracking
Flowcharting
Microprocessor chips
