Error Analysis And Correction Method Of PV Array I-V Test

With the conflict between economic development and environmental protection becoming more and more obvious,renewable energy is attracting more and more people's attention.As a kind of renewable energy,solar energy has a huge development space.In recent years,the number of photovoltaic power stations has gradually increased.In order to reasonably configure the photovoltaic power stations,the I-V characteristics of photovoltaic cells need to be tested in the field.The I-V field test method does not consider the influence of cable distribution parameters.However,the existence of cable distribution parameters will cause under-damped oscillation in the in-situ measurement of I-V characteristics.As a result,the obtained I-V characteristic curve has errors.Therefore,this paper carried out a study on the influence of cable distribution parameters on the field test of I-V tester.The main research contents are as follows:1?The influence of cable distribution parameters on the in-situ measurement of I-V characteristics is analyzed theoretically,and an improved model of dynamic capacitance charging test method is established.This model takes into account the influence of cable distributed resistance and inductance,and preliminarily judges that the cable inductance has the greatest influence on the in-situ measurement of I-V characteristics.Combining with the mathematical model of photovoltaic cell,the improved model of dynamic capacitance charging test method was built in MATLAB/Simulink,and the influence of cable inductance and capacitance charging rate was quantitatively analyzed.2?This paper gives the calculation method and selection standard of the test capacitance of I-V tester.In view of the current situation that I-V tester does not judge the accuracy of its own measurement,two calibration methods of I-V tester are proposed.The I-V tester was calibrated by battery and multiphase rectifier circuit,and the calibration method was simulated and verified.By comparing and analyzing the advantages and disadvantages of the two methods,it is determined that the multiphase rectifier circuit is more suitable for the batch calibration of I-V tester.3?The above I-V tester calibration method does not consider the influence of cable distribution parameters.This paper presents a test method to reduce the influence of inductance.The method includes two methods for testing the inductance of the cable.One is to obtain the different IV values at the current moment by using two sets of capacitors,and to solve the inductance value according to the model equation of inductance containing the cable.The other is to use a single set of capacitance to calculate the inductance value of the cable according to the test oscillation process of the cable.Based on the cable parameter model and actual measurement IV,the calculation method of inductance additional voltage is derived.Eliminating the effect of cable inductance voltage on the measured IV,the I-V tester can obtain more accurate output characteristics of photovoltaic array,and the feasibility of this optimization scheme is verified by using MATLAB software.4?A dynamic capacitance charging test platform was built by using Kewell portable I-V curve tester.The above optimization scheme is verified by experiments.Experimental results verify the effectiveness of the optimization scheme.