Microgrid Restoration after Major Faults in Main Grid with Automatic and Constant Time Switching

Abstract

— When a microgrid and distributed generation resources are disconnected from the grid for protection reasons, the restoration of microgrid (restoring distributed generation resources to feed the loads in microgrid) causes to increase the reliability of microgrid. When a fault occurs in the main grid, the reliability of islanded microgrid will be increased. In this paper a novel method for restoration of the microgrid is proposed when the fault occurred in the main grid. Therefore, we can take advantage of selling power energy during the fault. In addition, because of increasing in reliability, the price of energy will be increased. This paper selected a microgrid with two type of distributed generation resources, power electronic based distributed generation and small gas turbine with synchronous generator. Another purpose of this paper is to reduce restoration time. The proposed algorithm for automatic switching time is provided. This paper selected a microgrid system in medium voltage. The limitation voltage and frequency is according to IEEE 1547 standards, and simulation will be done by EMTP-RV with automatic and constant time switching separately.