PV SINGLE PHASE GRID CONNECTED CONVERTER USING FUZZY PID CONTROLLER

Abstract

This paper proposes the Single phase multy stage  grid interfaced Photo Voltaic System. The primary stage is DC-DC Booster stage which is governed  by a MPPT system. Output voltage of Booster stage is controlled by Incremental conductance  algorithm .Depending upon the solar Irradiation and temperature the output voltage of  PV panel is varied. By MPPT the maximum power is drawn from the PV system and fed to Inverter stage. This stage controls the power flow to the grid. The proposed control will reduce the voltage ripple in DC link voltage. The conversion efficiency of Inverter will decrease due to ripples in DC link voltage ,because it it will cause an excessive stress on the IGBTs or MOSFETs. This also results harmonics in the grid current. This paper describes  an efficient and reliable  control technique , Fuzzy Proportional Integral Differential (FPID) for stabilizing the DC- link voltage. PV Array output is varied with variations in solar irradiation, temperature and shadow that means Photo Voltaic  system is  nonlinear. The change of plant parameters will not affect the proposed control technique. In  this proposed scheme, power flow and THD levels  are analyzed at different DC-link voltage. This study describes that this  control technique have a capability to maintain a same grid current THD at transient and steady state conditions. Comparing to conventional PID control the % THD is small. Minimum settling time and fast DC-link voltage stabilization are also shown in this paper by this control technique. Finally the proposed system offers an excellent dynamic performance for reducing the DC-link voltage ripples and stabilization that is verified in MATLAB simulink tool