并网光伏逆变器孤岛检测技术

Islanding Detection Technology of Grid-connected PV Inverter

孤岛检测技术是光伏并网发电必需的一部分,但是在并网逆变器输出与负载功率平衡且负载谐振频率在电网频率附近时难以检测出孤岛。针对此种情况,文章研究了基于无功电流—频率正反馈的孤岛检测方法,推导出正确的正反馈系数取值范围。此方法不仅能有效快速地检测出孤岛,且在未发生孤岛时对逆变器输出电能质量基本无影响,其有效性和可靠性通过理论推导、仿真实验以及认证机构的认证得到充分证实。

It is indispensable to detect islanding in PV grid-connected generation. However, it is difficult to detect islanding in the case of power balance between the output of inverter and the load power, as the load resonant frequency is closing to the grid frequency. Thus the islanding detection method was researched based on the positive feedback of reactive current and frequency, and the accurate range of coefficient of positive feedback was detruded. This method can not only detect islanding quickly, but has no negative effect on the power quality of inverter output. Theoretical derivation, Matlab simulation and product certification experiment in CGC show that the proposed method is valid and reliable.