Harm of resonance caused by disconnection fault

Broken line resonance in severe cases, the superposition of high frequency and fundamental frequency resonance can make the overvoltage amplitude reach 2.5 times of phase voltage [P], which may lead to the displacement of system neutral point, overvoltage of winding and conductor, insulation flashover, lightning arrester explosion and electrical equipment damage. In some cases, the phase sequence of load transformer may be reversed, Overvoltage may also be transmitted to the low-voltage side of the transformer, causing harm.

The main measures to prevent broken line resonance overvoltage include:

(1) No fuse is used to avoid non full phase operation

(2) Strengthen the inspection and maintenance of the line to prevent the occurrence of disconnection

(3) Do not hang the no-load transformer on the line for a long time

(4) Ring network or dual power supply is adopted

(5) Phase to phase capacitance is added at the distribution transformer side,

The principle is: the capacitor is used as the energy absorbing element to absorb the energy in the transient process, so as to reduce the intensity of impact disturbance and suppress the occurrence of resonance. S-1 (O + 3C,) 1C. The phase-to-phase capacitance △ C is added at the distribution transformer side to increase 8-1 [Co + 3 (C, U + A0) / ca, Thus, the capacitance required to increase the equivalent capacitance C and the equivalent electromotive force EO can be calculated according to the method in literature [6]. (6) the use of transformer with good excitation characteristics can help to reduce the probability of broken line overvoltage