Tieline reconnection of microgrids using controllable variable reactors

In this paper, a tuned controller of variable reactors is developed to realize a reliable tieline reconnection of microgrids. It is very useful to solve the problem caused by synchronization issue during tieline reconnection, especially in absence of large-area communication network to cover all microgrids. The theoretical fundamental of this method is analyzed, based on which a set of tuning process of variable reactors' controller are derived. The feasibility and effectiveness of this tieline reconnection method with tuned controller is analyzed and verified by simulations. This method can greatly improve the transient stability of non-conventional grid, which consists of multiple microgrids and require an ability of frequent reliable reconnections, and limit system oscillation to less than 50%. The tieline reconnection controller can be easily integrated with power flow control into existing variable reactor devices at low cost. And the tuning process of the controller is simple and suitable for industrial applications.