无盲区低畸变的新型频移式孤岛检测方法

带正反馈的主动频率偏移法可通过增加扰动强度达到无盲区检测,但会产生更多谐波畸变,因此孤岛检测难以兼顾电能质量和检测灵敏度。针对上述问题,本文提出一种基于间断扰动及频率变化率的主动频率偏移式孤岛检测方法。利用孤岛前后电压频率变化率特征的不同,配合间断扰动作为正反馈扰动的启动条件,根据公共连接点频率及其变化率的偏移量对扰动方程中的正反馈系数进行模糊优化。与传统的主动频率偏移法相比,该方法在并网运行时注入的扰动数值小且扰动时间短,对电能质量的影响小;孤岛发生后又可以进行准确快速检测,且不存在检测盲区。通过Simulink搭建孤岛检测电路,仿真结果验证了该方法的优越性和有效性。

Novel Islanding Detection Method Based on AFD with No NDZ and Low Distortion

Active frequency drift(AFD)with positive feedback can eliminate the non-detection zone(NDZ)by increas ing the disturbance intensity.However,there will be more harmonic distortions accordingly.As a result,it is difficult for the islanding detection to take into account both the power quality and detection sensitivity.To solve the above prob lem,an improved AFD islanding detection method based on intermittent disturbance and frequency variation rate(FVR)is proposed in this paper.Combined with the characteristics of FVR before and after islanding,the intermittent disturbance is taken as the starting condition for positive feedback disturbance.Afterwards,the fuzzy optimization of positive feedback coefficient in the disturbance equation is carried out according to the frequency at the point of com mon coupling(PCC)and the drift of FVR.Compared with the traditional AFD method,the disturbance of the proposed method is smaller and has a shorter duration,thus minimizing the impact of disturbance on the power quality.After is landing effects occur,an accurate and fast detection can be carried out,and there will be no NDZ.An islanding detec tion circuit is built using Simulink,and simulation results verify the superiority and effectiveness of the proposed meth od.