Research On Current Detection Technology For Photovoltaic Grid-connected System

According to EPRI study shows that taking into account the full development of coal,hydropower and nuclear power in the case, in2010to2020between the country’selectricity supply and demand gap is still6.4%~10.7%. To fill this gap, we mustvigorously develop renewable energy generation, in which the development of photovoltaicpower generation industry is among the most important renewable energy.Performance of the inverter ultimately depends on the accurate measurement ofelectrical signals, where in the current detection is the most a key link, includingmeasurement of DC, AC, pulse DC and common mode leakage current. The real-timeaccurate current measurement is necessary for over-current protection, leakage detection,the optimization design of high performance inverter.This paper mainly studied the high accuracy, wide band, fast response speed of thecurrent detection technology in photovoltaic (pv) grid-connected system, presented a newGMR effect based current sensor with a closed-loop configuration. Compared with theexisting current sensor, the proposed current sensor has no offset and drift caused bytemperature variation, greatly reduces the error caused by hysteresis phenomenon, andimproves the precision, sensitivity and linearity. Moreover, the introducing of the magneticcore into the sensor effectively improve the sensitivity of the sensor, could measure currentto mA level, and the ability of the sensor for high precision weak current measurement isimproved.This paper set up a tested prototype for the new current sensor, and carried outexperiment and simulation. Simulation analysis and experimental results show that the newtype of sensor has good performance.