Design And Application Of Stand-alone Photovoltaic Power System Controller

The energy crisis and serious pollution of environment press us to consider the issue of energy development again. The development and application of new energy sources has become an inevitable trend all over the word. Solar power has obvious advantages, such as resource-rich, no pollution. Now, with the development of photovoltaic technology and low costs, photovoltaic becomes an important means of solar energy utilization. But PV systems still have some problems to be solved, the efficiency of energy conversion and the control strategies need further improvement. Thus, the research on relevant control problems of PV system has important significance.This thesis mainly focuses on the control problems of stand-alone PV system. The research includes simulation of the PV array, the maximum power point tracking (MPPT) control algorithm and the control of battery, then applied to a practical PV system. A simple and easy stand-alone PV system has been designed, which provide power to DC load through corresponding control strategies. The excess energy is stored in the sealed lead-acid battery. The state of PV system is real-time monitored by experimental Software. This system improves the conversion efficiency of PV system and uses the solar energy more efficiently.First, according to the mathematical equations of the PV array, build a photovoltaic array simulation model in Simulink. Using the model, analyze the relationship between the output characteristics of PV array and light intensity and temperature outside. Secondly, build the hardware circuit of stand-alone photovoltaic power generation system, including the PV array, buck circuit, controller, storage areas, load, testing links and other components. Finally, the control strategy is realized using dSPACE and MATLAB. This design uses the improved algorithm to control the system efficiently. In the comprehensive experimental commissioning phase, inputs are values of voltage and current, and the duty of buck circuit is output. The experiment software ControlDESK is responsible for monitoring the various parameters of photovoltaic systems and displaying the system status in real time.Simple stand-alone photovoltaic power generation system is designed in this paper. This system is based on practical application and easy to be implemented. The real-time simulation platform dSPACE DS1104is used as controller, which can connect with MATLAB seamlessly. The control algorithm can be compiled and downloaded directly by RTI from Simulink into DS1104hardware, shortening the development cycle. We can adjust the parameters of the program anytime. Simulation of photovoltaic power generation system provides a theoretical basis for practical application. The improved variable step P&O algorithm can track the maximum power point quickly and efficiently, prevent the loss of energy in stable period also. Take advantage of real-time simulation software ControlDESK to monitor system status. The system runs stably and efficiently and the research achieves good results.