A Tester For Photovoltaic Module Output Characteristic

A tester for photovoltaic (PV) module output characteristic can acquire output voltage and current data of PV module in real environment, which can be used to calculate the electrical parameters of PV module and provides basic parameters for the maximum power point tracking algorithm. The output characteristic and the structure of PV module tester are deeply studied in this thesis.The fundamental theories of PV cell have been studied. A simulation model has been established, the known parameters of which have been used to simulate the output characteristic curve in different external conditions. A kind of variable step sampling method is proposed based on the output characteristic curve of the PV module.Due to the output characteristics of PV module is matched with the charging characteristics of capacitor, a testing method for the output characteristics of PV modules based on dynamic capacitance is proposed in this thesis. A tester for PV module output characteristic taking the microcontroller as the control core is designed. According to the variable step size algorithm with acquisition circuit, continuously this tester detects the real-time voltage and current of the PV module output in the dynamic process in this thesis.According to the characteristic of the collected data, a filtering and a normalizing algorithm are designed. The software filter of the collected data makes the curve more clearly and the sampling data more accurate. The normalization processing of the collected data makes the tester suited for any power of the PV module and any load conditions.The tester for PV module output characteristic has been tested in actual field testing environment. Experimental results show that the actual curve collected by the PV module output characteristic tester and the simulation curve is almost consistent, which verifies that the data collected by the tester is effective.