Load power and frequency control based on modified droop method in hybrid systems-Wind Turbine/ Photovoltaic/ Fuel Cell-in Autonomous Stand-Alone Micro-grids

One of the major challenges in standalone micro-grids (MG), is the frequency control. In this paper, a method for frequency control in a hybrid system based on wind turbine / photovoltaic / fuel cell and super capacitor is proposed. The proposed method is the combine of load frequency control and super capacitor voltage control. To determine the references power, PI controller and modified droop control are used. System performance based on wind speed, solar radiation and the demand curve has been studied. The simulation results show that the control with modified droop method is better for damping of the frequency deviations, due to sending appropriate control signals to the generation units for balancing the network. MATLAB/ Simulink software environment is used for computer simulation.