一种快速小盲区的主动移频式孤岛检测方法研究

摘要

Aiming at the islanding detection speed and non-detection zone problem in photovoltaic ( PV ) grid-connected power system. A fast and smaller non-detection islanding detection method of active frequency drift with positive feedback method is proposed to solve the problem. In the method, the initial chopping fraction (cf) and the disturbance direction applied are determined by the zeroth-cycle difference between voltage frequency at the point of common coupling(PCC) and rated voltage frequency of grid. The sum of absolute value that each voltage frequency variation of PCC from zeroth to i cycle is applied to PCC. The islanding detection is completed within the detection period predetermined. Non-detection zone is described in the Qf0 ×Cnorm coordinate system and the islanding detection performance is simulated and analyzed with Matlab/Simulink. The results indicate that the new method meet the grid-connected power quality, meanwhile, the non-detection is smaller compared with AFDPF. Islanding detection time for the inductive load is shortened to 0.06 seconds. The islanding based on the capacitive load can be detected just 0.04 seconds. The islanding detection results meet the islanding detection standards of China.%针对光伏PV并网发电系统中孤岛检测速度、检测盲区等问题，提出了一种快速小盲区的带正反馈的主动频率偏移检测方法。该方法根据第0个检测周期的公共耦合点PCC的电压频率与电网电压额定频率之差来确定初始斩波因子及施加扰动方向；并对第i个检测周期以前PCC点电压频率变化量分别取绝对值后进行累加，将累加值作为正反馈量施加至PCC点，在规定的检测周期内，完成孤岛的检测。采用Qf0×Cnorm坐标系对算法的检测盲区进行描述，利用Matlab/Simulink对孤岛检测性能进行仿真分析。结果表明：相比AFDPF法，新方法在满足并网电能质量的同时，具有更小的检测盲区；对感性负载的孤岛检测时间缩短至0.06 s，对容性负载只需0.04 s即可检测出孤岛；孤岛检测结果符合我国孤岛检测标准要求。