A Research On Photovoltaic Water Pumping System And It's Control Strategy

Photovoltaic (PV) panels produce electricity directly from sunlight using silicon cells, with no moving parts. It drives the pump through series of new technologies of electronics, motors, control units and different modern devices to bring wafer up from river, lake or deep well. The system involves optical, mechanical and electronic theories and has an multi-across discipline property of studies. In recent years the price of solar module in international market as well as in Chinese market reduces strongly and goes with the standing technological progress of power electronics, PV water pumping system has been rapidly developed around the world. This dissertation deals with construction of PV water pumping systems, its motor driven technologies, maximal power point tracking together with optimization control of the systems and poly-pump systems. The corresponding system simulation and regarding programs were developed and described in this dissertation. Some theoretical analysis and experiments of PV water pumping system were also given in this thesis. The prospects of PV water pumping system in fields of technological and marketing development as well as some suggestions of improvements for future study are also discussed. The main contents of studies on PV water pumping system in this dissertation are as follow:1. Some analysis and comparisons between different systems.2. Some studies on control modes of the system, especially on a DC, PM, brushless and sensor-less motor driven systems. A method of rotor position identification without sensors has been developed. Using a microchip to increate system efficiency, anti-disturbing ability and reliability of PWM modulation.3. To develop a optimized control way for MPPT(Maximal Power Point Tracking) of the PV array. The stability of the system has been discussed.4. A new control concept and strategy for poly-pump system and its corresponding topological configuration are suggested. Using on-the spot bus communication technology to improve flexibility and efficiency of group control for PV water pumping.5. Some models for simulation and optimization of PV water pumping system are established and corresponding programs are given in this thesis. The results of simulation and optimization are really very useful for system configuration and sizing so that the installed systems could be more reasonable and reliable.6. Some necessary protective measures with artificial intelligence for PV water pumping systems are developed and realized, including dry operation identification, low speed, over load, low voltage operation and lightning protection etc.