Study On Fault Detection And Location Of Photovoltaic Array

Photovoltaic generation has become an important means of clean power generation,because it can convert solar energy into electric directly,and with clean,safe,green.However,PV arrays are usually installed in areas with good radiation resources,high altitude and big temperature difference between morning and evening.Due to the influence of these natural environments,PV array faults occur frequently.Therefore,it has great significance to detect and locate the fault location of photovoltaic array.In this paper,it has been studied that the faults of detect,judge and locate.They include open circuit faults,short circuit faults,aging faults and Shadow occlusion fault for PV arrays.The output characteristics of normal array and fault array have been analyzed by modeling and simulation.It has been constructed that a 1.5k W grid-connected photovoltaic generation system with 4 series and 2 parallel.And it has been compared that the results of simulation and experimental.The following research contents have been completed and corresponding conclusions have been obtained:（1）By using Matlab/Simulink,the simulation model of the PV module has been established based on the five-parameter method.The current common photovoltaic array configuration has been studied,and a 1.5k W（4 series and 2 parallel）grid-connected photovoltaic generation system has been constructed,and the corresponding photovoltaic array simulation model has been created.The simulation results have been compared with the actual test results of grid-connected photovoltaic generation system.（2）The output characteristics of PV arrays have been modeled and simulated,such as PV array of open circuit fault,short circuit fault,abnormal aging,Shadow occlusion and normal operation array.The characteristic parameters of different fault types have been determined by comparative analysis of the simulation results.（3）A method for detecting has been suggested that based on array real-time voltage and current index.Real-time characteristic parameter data of PV array has been collected,namely the output voltage and current of the array under the working condition of MPPT.And the voltage index ind_v,Current index ind_i have been calculated（namely the ratio of the real-time output voltage of the photovoltaic array to the open-circuit voltage,and the ratio of real-time array output current to short-circuit current;）.And voltage threshold t _VM,current threshold t _IM,short-circuit fault voltage threshold t _VS and open-circuit fault current threshold t _IO have been calculated(namely t _VM is the ratio of the theoretical maximum power point voltage and the open circuit voltage multiplied by the measured offset coefficient,t _IM is the ratio of the theoretical maximum power point current and short-circuit current multiplied by the measured offset coefficient,t _VS is the ratio of real-time theoretical maximum power point voltage to open-circuit voltage multiplied by the measured offset coefficient,t _IO is the ratio of real-time theoretical maximum power point current to short-circuit current multiplied by the measured offset coefficient).Then the array fault types can be judged by comparing the voltage-current index with the defined fault detection threshold.（4）An improved arrangement of voltage sensors has been suggested to determine the fault location.By analyzing the voltage output characteristics of key nodes of PV arrays,the voltage output characteristics of under normal operation and fault operation have been obtained,and the corresponding location judge conditions have been established.By comparing the real-time voltage sensor readings with the established location judge conditions,the occurrence location of fault modules can be accurately determined.（5）Based on the suggested fault detection and location method above,a device has been produced for fault detection and location of photovoltaic array.And applied to the 1.5 k W on grid photovoltaic generation system for experimental verification.The results show that the device can be judge the type of faults and accurately locate position of the faults,include short-circuit fault,open-circuit fault,anomalies aging and Shadow occlusion fault.