基于闭环锁频控制的并网逆变器孤岛检测方法

孤岛检测是分布式并网领域中研究的前沿问题之一。针对传统被动式检测方法检测盲区较大以及当前无盲区被动式检测方法控制算法复杂的问题,通过分析闭环锁频控制中实现频率跟踪的原理,研究闭环锁频控制的并网逆变器的高频阻抗特性,讨论各种孤岛情况下的负载阻抗特性,提出了一种新的被动式孤岛检测方法,该方法直接采用闭环锁频控制方法的输出频率,通过加入高频段阻抗检测防止了孤岛的发生。仿真和实验结果表明,所提出的被动式孤岛检测方法能够迅速准确地检测出逆变器断网情况,消除检测盲区,并且避免了控制算法复杂的问题。

Island Detection Method Based on Closed-loop Frequency-locked Control for Grid-connected Inverters

Island detection is one of the frontier issues in the field of distributed grid. Aiming at the problem of large non-detected zone in traditional passive detection method, the control algorithm of current non-detected zone passive detection method is too complicated, by analyzing the principle of frequency tracking in closed-loop frequency-locked control, the high-frequency impedance characteristics of grid-connected inverter controlled by closed-loop frequency-locked control are studied. By discussing the load impedance characteristics of various islanding conditions, a new passive island detection method is proposed, which uses the output frequency of the closed-loop frequency-locked control method directly, preventing the occurrence of the island by adding high-frequency impedance detection. Simulation and experimental results show that the passive island detection method proposed is able to detect the inverter disconnection situation quickly and accurately, can also eliminate non-detection zone, and avoid the complicated problem of control algorithms.