Resonance is a steady state

resonant overvoltage due to the long duration

its great harm.Once it happens

it will cause damage to electrical equipment and large area of power failure

so it needs to focus on and prevention.In this paper

an abnormal voltage accident of 500 kV double-circuit transmission line on the same tower caused by parametric resonance between high-voltage reactors and capacitive resistance is described.Through analysis of the fault waveform and simulation for fault current and fault voltage

the reason of this accident is verified. Finally

some measures are put forward in order to avoid similar accidents.