347 / 2022-03-15 16:50:17

Preventive methods for voltage sag on non-faulted line in distribution network caused by short-circuit fault

Voltage sag,distribution system,short circuit fault

With the increasing proportion of voltage sensitive loads in power system, voltage sag has become one of the most prominent problems. Recently, there are several cases of voltage sags in the distribution network in Zhejiang province. The short-circuit fault induced voltage sags occur not only on the faulty lines but also on the non-faulty lines. It’s urgent to figure out the mechanism of the voltage sags, especially on the non-faulty lines, and propose the preventive methods. In this paper, an electromagnetic transient model of a 20 kV distribution network is established by ATP-EMTP. The short-circuit fault induced voltage sag on the non-faulty line is reproduced. The effects of the grounding mode, the value of grounding resistance and short circuit impedance, the capacity of shunt capacitor on the value of voltage sag are studied. Low resistance grounding can effectively suppress the voltage sag and the lower the resistance is, the better the suppression will be. With the value increase of short circuit impedance, the transient voltage sag will also be suppressed. With the capacity increase of shunt capacitance, the voltage sag value shows an almost linear downward trend. When the grounding resistance is set as 20 Ω, short circuit impedance is 220 Ω, the shunt capacitor is 0.05 F, the non-faulty line will suffer no effect by the short-circuit fault