In order to solve the problem of power supply for intelligent integrated high voltage switchgear, the method based on LC resonance is proposed, and the hardware module has been designed: the supply power circuit contains high-voltage capacitors, isolation transformer winding in series, transformer secondary winding parallel Voltage divider and series matching inductors to achieve regulated output. A protection circuit based on energy pool voltage monitoring and power electronic switch control is designed for over -voltage and lightning impulse of line fault. The experimental data demonstrate the effectiveness of the circuit. Finally, the zero-sequence voltage measurement is realized by constructing the neutral current loop, which provides the technical condition for the single-phase ground fault detection of the intelligent switch.