A Novel Method of Frequency Regulation in Microgrid

摘要

Owing to generation and demand mismatch in a micro-grid, the frequency deviation and the rate of change of frequency (ROCOF) may become drastic at times. This is due to increased penetration of renewable energy sources that brings down the system inertia. Therefore, efficient control algorithms are required to mimic the inertial behavior of a conventional synchronous machine to arrest/limit the sudden change. This work focuses on frequency regulation of microgrid during transient conditions through the use of external energy reserve. The characteristics of a weak grid has been studied and simulated through modeling a virtual synchronous machine (VSM). An inverter model is also developed to integrate the ESS to the grid and a DSOGI-PLL is designed that is capable of synchronizing the system under distorted and unbalanced situation. Performance of the grid for different level of injection (using ultracapacitors or batteries) is highlighted. A switching between the sources is also demonstrated for selection of optimum combinations of different energy sources to improve the dynamics of frequency variation.