Research on Design of Relay Protection Structure in Smart Microgrid-Zero Sequence Current Protection

The development of smart microgrid is an important supplementary part of China's power grid construction, and relay protection design is an important guarantee for the stable and safe operation of smart microgrid. In the relay protection structure, zero-sequence current protection has the advantages of high sensitivity, good quick action, no influence of overload and system vibration, and is widely used in power grids with voltage levels of 110kV and above. In this paper, according to the operation situation and line parameters of typical 110kV multi-power supply network, the action current value is set and calculated, and its protection range is analyzed. The zero-sequence current protection structure is designed, and the acceleration mode when it works with automatic reclosing is discussed. The zero-sequence current protection studied in this paper is simple and economical. When zero-sequence current protection and automatic reclosing work together, it has unique advantages in improving the reliability of power supply in power system and has high practical application value.