The security and stability of public DC system is relative to division and unity of 10kV switches,startup and shutdown of common equipments,service of emergency lighting in the plant,and so on.

The combination of communication DC power supply system and substation DC power supply system can save investment and minimize maintenance.

Causes analysis about one point earthing leading to breaker tripping in DC system;

Grounding fault detection based on wavelet entropy and neural network for loop net of DC system;

Research of embedded system based on ARM in DC system grounding fault detection;

Earth fault analysis of direct current system;

Discussion about mixed use of different direct currents in double direct current system

The paper presents the status of and the operation method take by the accumulator as well as the direct current system one by one to ensure the reliable and steady-going operation of the whole system.