Research On Photovoltaic Generation System And Its Control

At present, while most countries all over the world are developing green and renewable energy, solar energy is accepted commonly because of its unusual advantages. Photovoltaic (PV) systems are paid more attention to among its various applications. With price reduction of PV modules and development of PV technology, the role of PV generation systems is gradually changed from supplemental energy to substitute energy. And stand-alone and grid-connected PV generation systems will be the trend among PV applications. This paper deals with such key problems as true maximum power point tracking (TMPPT) of PV array and optimum management of battery, improvement of inverter output wave, islanding effect and so on by establishing related simulation models, applying novel control strategies and experiments validation. The more details about author's work are as follows:1. The performances and characteristics of PV generation systems with different topologies are described in details.2. A novel control strategy is developed in which power variation of load is used instead of the power variation of PV array output to track the maximum power point of PV array. And TMPPT of PV array is realized by applying the variable step voltage disturbance control algorithm. In addition to that, the function combining the optimum management of battery with the TMPPT of PV array is attained by improving the control algorithm in stand-alone PV generation systems .3. The sine-wave inverter operation principle of residential stand-alone PV generation system is analyzed in details. And the fuzzy adaptive PI control strategy based on the output voltage feedback is presented, corresponding experiments are done. The experiment results show that the control strategy above improves dynamic performance of system more efficiently than traditional PI control.4. The operation principle of residential high frequency PV grid-connected generation system is analyzed in details. The novel strategy which combines the repetitive control with the utility voltage feedforward control is presented for the first time. The corresponding simulation model is setup, related simulations and experiments are done. The results show that the total harmonic distortion (THD) of grid-connected current wave is reduced by strategy above.5. The mechanism of islanding occurring is analyzed and studied in details. The strategy of anti-islanding based on the active frequency drifting is improved. And the correspondingsimulation model under Matlab/Simulink environment is established for the first time and some experiments are done according to the strategy above.6. The software and hardware experiment set of PV generation system based on the high performance DSP chip of TMS320LF2407A is developed with functions of high speed data acquisition, event managements, complex control algorithm and intelligent protection measures of the system .7. The system monitor, display and communication software which based on the VB6.0, high performance DSP chip of TMS320LF2407A and W77E58 chip, is improved, which provides communication and remote monitor of PV generation system.