基于改进单相dq0电压检测的混合式配电变压器负载电压控制投切策略

The load voltage compensation unit of hybrid distribution transformer (HDT) should be switched on or off with the variable conditions of the distribution network. To improve the limitations of the existing voltage detection methods, this paper proposes an novel detection method with improved dq0 transformation method. Specifically, the three-phase virtual voltages for each phase grid voltage are built by the method of derivation, and these virtual voltages are transformed from the static coordinate to the dq0 coordinate, then the three phase voltage swell, sag and asymmetry can be detected by the simple comparing method. The advantage of this novel detection method is that just a low pass filter with small time constant is adopted to eliminate the high order harmonics, then the low pass filter with long delay used in the traditional methods can be cancelled, thus both the detection response and accuracy of the novel method are improved. The simulation model is built in Matlab/ Simulink, the load voltage compensation unit can be switched on or off by the generated detection signal with reverse parallel thyristors, which verifies the correctness of the proposed method.