FOFFT Based Grid Connected PMS Motor Driven Solar Water Pumping With Improved Power Quality

Abstract

This paper contributes for the development of a novel technique for solar energized grid integrated water pumping system which is driven through PMS motor. The impetus for proposing this technique is to provide incessant operation of a water pumping system without accounting for variations in solar insolation with improved power quality. When the power extracted from PV exceeds to the pump load requirement, the excess power is fed to the linked grid, and if the PV power is not sufficient to operate the pumping system, the grid supplies the remaining power to keep the pumping system running continuously. By improving the power quality, the system becomes more reliable, accurate, and effective. Here, system is tested through a logic in which, if irradiance is above 500 W=m2, solar energy is fed to grid after feeding the pump load demand and refrence speed for the pump is evaluated based on the solar generation. On the other hand if irrdiance is below 500 W=m2, PV power is not able to match the pump demand. In this condition the pump is supplied by the PV array as well as grid and reference pump speed is set to the rated speed for full capacity operation as the utility grid is infinite source. To make such system, we have connected a voltage source converter for utility grid control and a voltage source inverter for PMS motor control to the dc link. Unit vector template theory is also used to control the bidirectional power flow between a solar PV system and the linked utility grid. For filtering the polluted grid voltage and estimating synchronising components, a FOFFT (Fourth Order Fundamental Filtration Technique) based control algorithm is used. The incremental conductance technique is used to obtain the duty ratio for MPP operations in MPP tracking. The sensorless vector control technique is used to control the speed of the PMS motor. MATLAB/Simulink is used to develop and test the proposed methodology.