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为保护系统及人身安全、保障用户供电质量,燃料电池并网系统必须具备孤岛检测功能。文中提出一种检测速度快、盲区小的新型孤岛检测方法——ASMS_Q法。该方法对滑模频率偏移法进行改进,在偏离工频较大区域加入加速增益,并结合q轴无功电流扰动法,在电网断开后,进行更快速地频率扰动,使其超出正常范围,达到过/欠频保护。而且电网正常工作时,给电网注入扰动量很小,对逆变器输出电能质量没有影响。在Q_f-f_0和Q_(f_0)-C_(norm)坐标系下,对比分析了ASMS_Q法及两种传统方法的盲区。仿真和实验结果表明,ASMS_Q法比传统的主动式检测方法盲区更小,检测速度更快,适用于高品质因素的负载。
To protect the system and personal safety, to protect the quality of power users, fuel cell grid system must have island detection. In this paper, a new detection method - ASMS_Q is proposed, which is a new island detection method with fast detection speed and small dead zone. This method improves the sliding mode frequency shift method, adds acceleration gain in the region deviated from the large working frequency, and combined with q-axis reactive current disturbance method, after the power grid is disconnected, the frequency disturbance is performed more rapidly than normal Range, over / under frequency protection. And when the grid is working normally, the amount of disturbance to the grid is very small, which has no influence on the output power quality of the inverter. In the Q_f-f_0 and Q_ (f_0) -cnorm coordinate systems, the ASMS_Q method and two traditional blind methods are compared and analyzed. Simulation and experimental results show that the ASMS_Q method is less blind and faster than the traditional active detection method and suitable for high-quality load.