Active and reactive power sharing of parallel inverters in microgrid by using droop control

The spread of greenhouse gas emissions in the atmosphere resulting from generating electricity based on fossil fuels and emergence of distributed generation systems as a clean energy sources (wind turbines, PV, Fuel cells, etc. ) lead to begin transfering from conditional electrical grids to smart grids. These grids have a features to integrate distributed energy resources and use communication technologies. So utilization of distributed renewable energy sources for domestic energy consumption will increase in the near future. This trend allows more efficient energy consumption because of reducing transmission loses and dependence on domestic appliances to grid distribution.The distributed energy resources are connected into the grid via power electronic interface such as inverter or ac/ac converter. In this thesis, it is studied the methods used to manage and control active/reactive power sharing of inverters. Also it is reviewed the advantages and disadvantages of many types of control methods used for power sharing of parallel inverters. This study is aimed to propose a controller for active and reactive power sharing of inverters operated in parallel. At first we designed droop control to make power sharing of parallel inverters on several cases. After that we modify a droop method by designing PID controller and connect it with droop control. The proposed controller consisting of droop and PID controllers gives more accurate power sharing by removing signals in transient response and gives more accurate results especially in reactive power sharing. Key words: Active and Reactive power sharing, Distributed energy resources, Droop control, Inverters, Microgrid, PID controller