基于盲区判别的混合型孤岛检测方法

摘要

孤岛检测是分布式发电系统并网逆变器必须具备的功能,针对被动型检测方法盲区大及主动型方法对电能质量产生影响这两个不足,提出了主被动结合的混合型孤岛检测方法.该方法分析并推导出被动型方法盲区判别式,在工频周期内对系统运行状态进行计算和盲区判别,判断是否引入电流偏移实现Sandia频率偏移法的孤岛检测.在被动型方法的盲区内引入Sandia频率偏移法的混合型孤岛检测方法能有效地检测出孤岛状态,实现无盲区检测,也能较大地减小主动式方法对电网电能质量产生的影响.通过Matlab仿真验证了该混合型方法的有效性.%Islanding detection is an important function of distributed generation (DG) system with connected converter.To solve the problem of large non-detection zone (NDZ) of passive methods and obvious effect of active methods on power quality,a new hybrid method is proposed by combining the passive and active methods.The NDZ criterion is analyzed and derived with passive methods,and Sandia frequency shift (SFS) method is introduced based on the detection criterion by calculating the data from the operation system withinone frequency cycle.By combining the passive method and SFS,the hybrid method has the advantage of realizing detection without NDZ and less effect on power quality due to the active method.The simulation results in MATLB verify the effectiveness of the hybrid method.