Frequency Control of Wind and PV Based Isolated Microgrid

The wind and solar PV based isolated microgrid can be economical and reliable for the remote area where the grid is not available. The frequency and voltage fluctuation are major problems in such remote microgrid due to intermittent nature of renewable resources like wind and solar PV. The frequency fluctuation should remain within acceptable limits for stable operation of the remote microgrid. This thesis work focuses on frequency control of wind and photovoltaic (PV) based isolated micro-grid using traditional droop control technique. The battery system acts as a master unit which is responsible for setting up the common AC bus voltage and frequency. The proportionalresonant (PR) voltage and current controllers are designed to control the current and voltage output of the voltage source inverter (VSI) connected with the DC battery. The better control performance can be obtained by using PR controller which easily tracks reference signal and eliminates steady state error in resonant frequency. The traditional droop control method is applied to generate voltage and the frequency reference set points for the VSI controller to control frequency of the AC micro-grid. The detailed analysis of the frequency control is performed by conducting two different case studies and load sharing between inverters is also presented to observe power shared by different inverters in isolated microgrid. In all the cases, system frequency is maintained within the acceptable range for the stable operation of wind and solar PV based isolated microgrid