With microgrids gaining more popularity in effectively meeting the increasing power demand, the operational challenges keep on increasing hand-in-hand. Especially when the microgrid work in islanded mode, it has to supply its area loads and maintain the system parameters as per the standards. This requires systematic coordination among the distributed generators so that the real and reactive power sharing is proportional to their ratings, simultaneously maintaining the system voltage and frequency at the rated values. While a droop controller shares the real power accurately, it is ineffective for precise reactive power sharing. The errors in reactive power sharing are compensated by adding virtual impedance in series with the distributed generator. The key objective of the work is to estimate the virtual impedance value to nullify the reactive power sharing errors without the need for communication links. A fuzzy logic controller is proposed to estimate the value for virtual impedance based on the real and reactive power demand at that particular instant. The virtual impedance dynamically changes depending on the load demand in order to compensate for the feeder impedance mismatch and hence called adaptive virtual impedance. Thus with the proposed fuzzy logic controller, accurate reactive power sharing is made possible without the requirement of communication links and the knowledge of feeder impedance. A secondary controller is also included to restore the frequency and the voltage to the rated values. A microgrid with equally and unequally rated DGs has been simulated in Matlab Simulink with the proposed fuzzy controller and successfully validated.

随着微电网在有效地满足不断增长的电力需求方面越来越受到欢迎，操作挑战越来越紧密地联系在一起。尤其是当微电网以孤岛模式工作时，它必须提供其区域负载并按照标准维护系统参数。这需要分布式发电机之间的系统协调，以便有功和无功功率分配与它们的额定值成比例，同时将系统电压和频率保持在额定值。当下降控制器精确地共享有功功率时，它对于精确的无功功率共享是无效的。通过添加与分布式发电机串联的虚拟阻抗，可以补偿无功功率共享中的误差。这项工作的主要目的是估计虚拟阻抗值，以消除无功功率共享误差，而无需通信链路。提出了一种模糊逻辑控制器，以基于该特定瞬间的有功和无功功率需求来估算虚拟阻抗的值。虚拟阻抗根据负载需求动态变化，以补偿馈线阻抗不匹配，因此被称为自适应虚拟阻抗。因此，利用所提出的模糊逻辑控制器，无需通信链路和对馈线阻抗的了解就可以实现精确的无功功率共享。还包括一个辅助控制器，可将频率和电压恢复到额定值。