A New Power Flow Controller For Microgrid

Renewable energy sources(RES)are playing an important role in today‘s grid but its intermittent and random nature make the control difficult.Conventional droop control is no longer efficient and auxiliary energy storage method is limited by its high cost.Load varying method based on available generation can be another solution,such as novel Electric Spring(ES).Electric Spring adopts the demand side management control where the load demand follows the power generation without any need of communication and it can effectively regulate the mains voltage despite the fluctuation of the power generation.However,ES cannot shape power in the generation side,which causes improper power distribution at the subnetwork level and even stability problems for the system.This thesis proposes the concept of resistive ES based power flow controller,which could effectively shape the load flow at subnetwork level and stabilize mains voltage fluctuation with the combination of resistive ES and PEAT(Power electronics based adjustable transformer).With PEAT being incorporated in the stepdown transformer at grid side,non-critical loads or even the total loads power could be controlled supplied by RES locally,decreasing the power dependency on grid,thus improving the grid stability.The principle,realization and case studies are presented in this thesis.Simulated model of the controller shows that it is an effective way to control power flow in the future Micriogrid with intermittent RES.