Study Of Control Strategy On Photovoltaic Powered Water Pumping System

Photovoltaic powered water pumping system automatically starts working when the sun rises and stops working when the sun is set. It's easy to maintain. So it's a green energy product with economic, reliability and environmental benefits. Currently, the efficiency of commercial photovoltaic water pumping system varies widely, up to 60%, and as low as 10%. Therefore, to improve the water pumping system's efficiency, to make photovoltaic array's output power close to the maximum power, to make the pump's speed adjusted according to changes of light intensity, considering application characteristics of household photovoltaic water pumping systems driven by induction motor, combined with the motor's vector control theory and TMPPT / PID dual-mode control algorithm, the new varied frequency speed control strategy is theoretically analyzed and simulated. The main contents are as follows:1. Photovoltaic water pumping system's structure, characteristics of performance and application are studied. The varied frequency speed control strategy, the core of which is TMPPT / PID control algorithm and vector control, is determined.2. The principle and control algorithm of vector control and space voltage vector pulse width modulation, their implementation method with TMS320LF2407A DSP are analyzed. Besides, based on these work, the vector control chart of the PV water pumping system is got.3. Advantages and disadvantages of a variety of photovoltaic water pumping system's maximum power tracking control strategies are researched and analyzed; the TMPPT / PID dual-mode control algorithm is thus proposed, and its feasibility is simulated and certificated.4. According to the applied characteristics of photovoltaic water pumping systems, the structure of its main circuit is determined; the push-pull booster circuit is chosen as DC/DC part, IPM as the core of DC/AC. The control circuit and unique protection circuits of photovoltaic water pumping system are reasonably designed. TMS320LF2407A DSP is chosen as the core of the control circuit.5. The varied frequency speed control strategy of PV water pumping system is simulated and analyzed. Experimental results show that the system can track the maximum power point in real time and the pump's speed can be regulated according to changes of light intensity. The speed control process has good dynamic performance.