Research On High-Power Photovoltaic Array Simulator

Doing experimental research of photovoltaic power generation system by solar photovoltaic array simulator instead of the actual solar cells, can not only greatly shorten the development cycle, but also reduce the development costs, with higher efficient R & D and more reliable experimental data. As the photovoltaic power level gradually improving, the study of photovoltaic power generation system technology will become increasingly difficult. Therefore, researching the photovoltaic array simulator suiting for high power is becoming particularly important.This paper firstly introduces the overall architecture of the solar photovoltaic system and the function of each part, analyzes the working principle of photovoltaic cells, equivalent circuit and mathematical model of the project, and builds the corresponding simulation model. Simulation experiments of the output I-V, P-V curve about photovoltaic cells under standard ambient environmental conditions and variations, lay a good foundation of the study for the simulator system.The single-module main circuit of the simulator in this article adopts the single-stage Boost DC/DC topology. Except simple structure, it can also revise high power factor when completing DC/DC voltage conversion. The paper has analysised the working principle and working process of the main circuit in detail, and calculated some important parameters. Theoretical research and analysis for the feasibility of multi-module parallel in equivalent current with high power output are made.Two kinds of intelligent control algorithms-fuzzy control algorithm and fuzzy PID control algorithm have been studied for simulator, and corresponding fuzzy PID controller based for this simulator system has been designed. The fuzzy PID control algorithm combines merits of PID control algorithm and fuzzy control algorithms, which endows the simulator with a fast response and accurate tracking. By engineering mathematical model for photovoltaic cells, the simulator's output voltage signal is converted to a reference output current that is used to compare with the actual output current to obtain the current error signal and the differential error as the fuzzy controller inputs. After processing in the fuzzy controller, the model can gain the change of three PID parameters. Then the parameters of the PID are further adjusted to obtain the switch duty cycle which controls the simulator's output characteristics, thereby the purpose for simulating and tracking the output characteristics of photovoltaic cells is realized.In order to prove the effectiveness of multi-module parallel design for main circuit and the remarkable performance of the algorithm, the simulation model has been designed based on Matlab and Psim. Simulative experiments have been done to certify the static and dynamic output characteristics for the simulator of the dual-module system mentioned above. Simulative results show that the topology of main circuit and corresponding algorithm can track changes at the reference operating point quickly and accurately, and thus achieve a comprehensive simulation for the solar cells'characteristic curves on various environmental conditions.