The sensitivity and selectivity of electronic protection relay’s constant value is directly influenced by the power system zero-sequence network’s stability, which is the foundation of safe and reliable operation of the relay protection. Zero sequence network topology is formed by transmission line and directly-grounding neutral point of transformer. Analysis shows that the integrated use of automatic reclosing of the transmission line and automatically switching grounding neutral point of transformer will ensure the equipment after tripping can resume the zero sequence power system networks as soon as possible. This technology is the optimal control technology of the zero sequence power system networks. In the following, it summarizes the automatic reclosing technology of transmission lines, researches the technology of automatic switching the grounding neutral point of transformer, and develops the corresponding control device. Device performance has been tested in actual operation and verification, which meets the application requirements.