Bi-Directional Power Flow Control in Grid Integrated Solar PV Connected Water Pump System

Abstract

This paper proposes a grid connected solar photovoltaic (PV) fed water pumping system for agriculture and irrigation purposes, with bi-directional power flow functionality. PV generated power can be transferred into the grid when water pumping is not needed, to improve its capacity utilization factor. It is achieved by the voltage source converted integrating the DC link of the conventional single stage or two stage PV fed water pumping system, proving several other benefits. The pump can run at its duty point (efficient point) in spite of large variation in the insolation level. For applying the <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$\boldsymbol{dq}$</tex> control technique, the single phase grid voltage is taken as a real signal, and an imaginary signal is generated by shifting it by 90°. These real and imaginary signals are considered <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$\alpha\beta$</tex> , and <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$\boldsymbol{dq}$</tex> transformation is achieved. The voltage source converter tries to keep the DC link voltage constant at a specified reference. This proposed system allows the consumer to use the water pump at full capacity throughout the day, irrespective of the weather condition. The consumer can also export the PV power generated when the water pump is not being used. Maximum power point operation of PV array is also achieved in this system.