基于自适应虚拟惯性的微电网动态频率稳定控制策略

微电网作为分布式电源的有效载体,通过分布式电源并联连接形成独立电网。而微电网中传统下垂控制的输出频率动态响应速度快,在负荷频繁波动下易受到较大扰动。为了提高微电网频率的动态稳定性,文中提出了一种基于自适应虚拟惯性的同步发电机的控制策略,该方法模拟同步发电机的行为,构造频率变化率与虚拟惯性的关系,自适应改变虚拟同步发电机控制的惯性,从而提高微电网系统抗干扰能力和过载能力。相比于传统的交替惯性方法,所构造的自适应惯性算法不需要采样频率微分项,避免了引入系统噪声,同时实现了惯量的平滑灵活调节,具有较强的鲁棒性。另外,利用李雅普诺夫稳定理论分析了所提算法的收敛性和稳定性。仿真和实验结果表明所提方法提升了微电网频率的动态稳定性,从而验证了所提控制策略的可行性和有效性。

Dynamic Frequency Stability Control Strategy of Microgrid Based on Adaptive Virtual Inertia

As an effective carrier of distributed generators, microgrid is an independent power grid by parallel connection of distributed generators. However, the conventional droop control has a fast dynamic response speed to output frequency and is easily disturbed by frequent fluctuation of load. In order to improve the dynamic stability of the microgrid frequency, this paper proposes a control strategy of synchronous generator based on adaptive virtual inertia. The proposed method simulates the behavior of synchronous generator, constructs the relationship between the frequency change rate and the virtual inertia, and adaptively changes the inertia of the control of virtual synchronous generator. Thus the capacity of the microgrid in resisting disturbance and overload is improved. Compared with the conventional alternating inertia method, the proposed method does not require sampling frequency differentiation terms, which avoids the introduction of system noise. Meanwhile, it achieving flexible adjustment for smooth inertia coefficient, and has strong robustness. In addition, the convergence and stability of the proposed algorithm are analyzed and proved by Lyapunov stability theory. Simulations and experimental results show that the proposed method can improve the dynamic stability of microgrid frequency, and the feasibility and effectiveness of the proposed control strategy are verified.