Reactive power flow control of grid tie inverter to enhance the stability of power grid

This paper studies the reactive power compensation schemes using grid tie renewable energy inverters for future power grid with substantial renewable energy power generation. A traditional grid tie renewable energy inverter becomes a dynamic reactive power compensator. The objectives of the compensator are 1) to regulate the output voltage of the inverter and 2) to enhance the grid frequency stability. We propose a coordinated control scheme for the inverter to automatically select either voltage control or frequency control operation modes depending on the power grid conditions. The control scheme is tested in a microgrid system using Matlab/Simulink simulation. The performance is compared with the inverter without reactive power control and inverter with reactive power control for output voltage regulation. Simulation results show that a proper coordinated control scheme can improve both the voltage and frequency stability of the power grid.