基于直流源充磁的改进选相合闸策略

Improved Phase Selection Closing Strategy Based on DC Magnetizing Circuit

电力变压器合闸时可能产生的励磁涌流会严重影响电力系统的稳定运行,现有合闸策略下选相合闸的实现受限于控制精度和剩磁测定方法。依据变压器合闸角改变时的励磁电流变化规律,存在一剩磁范围,使变压器在较大的合闸角范围合闸而不出现励磁涌流,利用直流充磁电路配合改进后的控制策略能够使变压器剩磁处于该范围。利用Pscad中的J-A磁滞模型仿真得出剩磁处于额定剩磁的0.7到0.8时,有最大的合闸角范围,利用直流充磁电路充磁0.021 s到0.022 s可以使变压器剩磁处于上述范围。结果表明该方法能够调整变压器铁心剩磁到指定范围,充磁电路无需依据实际调整控制参数,较大范围的合闸角降低了选相合闸的控制精度并且能够有效抑制励磁涌流。

The exciting inrush current possibly generated in the closed operation of power transformer will seriously affect stable operation of power system.The realization of existing phase selection strategy is limited to the control accuracy and remanence measurement method.According to the variation of exciting current in case of variation of closed angle of transformer,a range of remanence is existed,keeping the transformer close at a larger range of closing angle without exciting inrush current.The use of DC magnetizing circuit with the modified control strategy can keep transformer's remanence in this range.When the remanence is 0.7 to 0.8 of the rated remanence which is obtained by the simulation of J-A model in Pscad,the the maximum closing angle range is existed.The use of DC magnetizing circuit to magnetize 0.021 s to 0.022 s can make the transformer's remanence in the above-mentioned range.The results show that the method can adjust the remanence of transformer core to the specified range,the magnetizing circuit does not need to adjust the control parameters according to the actual situation,and the large range of closing angle can reduce the control precision of phase selection closing and effectively suppress the exciting inrush current.