基于非线性最小二乘曲线拟合的虚拟同步发电机惯量与阻尼系数测量方法

A VSG Inertia and Damping Measurement Method Based on Nonlinear Least-Squares Curve Fitting

虚拟同步发电机(VSG)技术是解决经由电力电子变流器并网的新能源发电渗透率逐渐提高下系统惯性与阻尼减小问题的有效手段。目前的VSG研究多侧重于技术的优化与改进,少有特性测量方面的研究成果。在实际的VSG应用中也通常是使用惯性时间常数τ综合表征系统转动惯量J与阻尼系数D,这种表征方式中转动惯量与阻尼系数耦合,无法明确各参数的具体数值。为了解决该问题,基于非线性最小二乘曲线拟合法,分析了发电系统在离网、并网不同运行工况与阻尼状态的时域单位阶跃响应函数。定性介绍了一种利用动态响应指标测量J、D的方法。实际测量方法以曲线拟合法为基础,借鉴了一种用于同步发电机转动惯量测量的甩负荷实验,结合并网功率阶跃实验,得到了一种可以自验证的综合测量方法。最后通过多组不同参数与工况的仿真与实验验证了该方法的有效性。

The Virtual Synchronous Generator(VSG) technology is an effective means to solve the problem of system inertia reduction under the increasing penetration of new energy that connect to the grid by power electronic converter. The current VSG researches mostly focus on the optimization and improvement of control strategies, and there is few study on testing the output characteristics of the VSG.In the actual VSG application, inertia J and damping D are generally represented by a inertia time constantτ, in which way the specific values of the parameters can’t be figured out for the coupling. To solve this problem, the time domain step response functions of power system in different work status and damping status are analyzed based on nonlinear least-squares curve fitting. Besides, a measurement method using dynamic response indicator is introduced qualitatively. Based on the nonlinear least-squares curve fitting,a self-verifying comprehensive measurement method is obtained by referring to load rejection experiment for synchronous generator inertia test and grid-connected power step experiment. The effectiveness of method proposed in this paper is verified by multiple sets of simulations and experiments.