Sensorless control of inverter dc-bus voltage combined with modified PQ control using extended Kalman filter in a photovoltaic system

this paper presents a sensorless control approach of inverter dc-bus voltage using extended Kalman Filter (EKF). A positive sequence detection of grid voltage and load current is also proposed. The dc-bus voltage estimated by EKF is combined with the modified instantaneous power (p-q) control technique for photovoltaic system application to improve electrical energy quality at the grid under photovoltaic (PV) varying temperature and radiation and also distorted grid voltage ensuring at the same time the supply of unbalanced nonlinear load. The ac grid receives the required active power from the PV cells through boost converter, dc-bus and inverter. It supplies the energy to unbalanced nonlinear load in case of absence of PV energy. The boost converter control extracts the maximum power point from PV cells by Disturb and Observe (P&O) algorithm. Mathematical relationships of different parts of PV system are described and studied. The control system is simulated using the SimPower blockset of Matlab/Simulink. Simulation results have showed that the proposed methodology is an efficient solution to PV control system.