Microgrids have gained much attention in recent years. The main challenge of this system is controlling the voltage and frequency in islanded mode. The inverter-based distributed generators (DGs) have low inertial property and in load change, the microgrid frequency and voltage are easily violated. Using the synchronous generator (SG) control concept, the inertial property of SG results in more stability of frequency and voltage in microgrid. In other hand, droop method is the basic idea of control in islanded mode. However, the simple or modified droop method cannot guarantee returning the main parameters to the reference values when they are violated. Thus, combining the control concept of SG and also modified droop method can enhance the voltage and frequency stability and ensure returning the violated values to the reference ones. The main goal of this paper is proposing this combinational control while simulation results show that using the proposed control strategy, the stability of frequency and voltage is improved even in sudden and different load changes compared with other efficient works in this filed. Moreover, without control strategy, the instability in frequency and voltage may be undesirable in the proposed system as discussed in the paper.

中文翻译：

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同步发电机控制概念和改进的微电网频率和电压稳定性下垂，包括基于逆变器的 DG

近年来，微电网备受关注。该系统的主要挑战是在孤岛模式下控制电压和频率。基于逆变器的分布式发电机（DG）具有低惯性，在负载变化时，微电网频率和电压容易被破坏。使用同步发电机 (SG) 控制概念，SG 的惯性特性使微电网中的频率和电压更加稳定。另一方面，下垂方法是孤岛模式控制的基本思想。但是，简单或修改的下垂方法不能保证主参数在违反时返回到参考值。因此，结合 SG 的控制概念和改进的下垂方法可以提高电压和频率的稳定性，并确保将违规值返回到参考值。本文的主要目标是提出这种组合控制，而仿真结果表明，与该领域的其他有效工作相比，使用所提出的控制策略，即使在突然和不同的负载变化下，频率和电压的稳定性也得到提高。此外，如本文所讨论的，如果没有控制策略，频率和电压的不稳定性在所提出的系统中可能是不希望的。