Research on the Influence of Microgrid to Distribution Network Protection and Improvement Measures

Abstract

In the context of increasing energy shortage, the application of various renewable and dispersed energy sources for power generation and energy supply will become increasingly widespread. As a small local power grid containing multiple distributed power sources connected to the distribution network, micro grid (MG) can be linked to the distribution network to operate, or can be disconnected from the distribution network to operate when the grid fails or when is needed. Due to the randomness of distributed power and load operation in MG, the direction of power transmission between MG and the distribution network is also uncertain. When the distributed power generation capacity of MG is small and the load level is high, MG must absorb electrical energy from the distribution network to meet the demand of the internal load of itself, which is equivalent to operating in the load state; and when the amount of power generated by the distributed power supply is large, the excess power will be sent back to the distribution network, which is equivalent to the power supply state, and this case will have a great impact on the original protection of the distribution network. In this paper, through the establishment of MG and distribution network grid structure simulation, the impact of MG to distribution network protection in power supply state and load state is analyzed respectively and a variety of improvement measures are proposed based on the actual situation.