含高比例虚拟同步机的微电网振荡机理与抑制方法研究

Virtual synchronous machine(VSM) is a power electronic converter with the characteristic of inertia and damping as traditional synchronous machine, which makes it possible to be widely used in micro grid. However, it not only inherits the low-frequency oscillation problem from the traditional synchronous machine, but also brought micro grid the new problem of high-frequency oscillation, which lead the oscillation frequency band of the micro grid to become wider. On the other hand, VSM has the characteristics of various parameters, fluctuation and dynamic coupling, which lead the oscillation mode complex and changeable. For the wide and coupled oscillation problem in micro grid, the parameter perturbation principle refer to the output characteristics of distributed generator is firstly researched. Then, the actual produced inertia and damping of VSM can be estimated. Secondly, the dynamic process of high oscillation in coupling environment is analyzed. Then, the mathematical description of the dynamic process is put forward. At last, the wide band oscillation model of multi VSMs micro grid is established. Also, unstable determination method and oscillation suppression method are proposed. The findings of this project may be helpful for solving the oscillation problems of micro grid in trend of large-scale VSMs power supply to power grid. The findings also helpful for improving the operational stability and reliability, and for promoting the development of renewable energy efficiency.

虚拟同步机（virtual synchronous machine, VSM）是模拟传统同步机运行特性的电力电子变换器，可解决分布式电源惯量和阻尼缺失问题，有望在微电网中得到大规模应用。然而，VSM不仅继承了传统同步机的低频振荡特性，同时还给微电网带来了高频振荡新问题，导致微电网振荡频带大幅拓宽。另一方面，相比于传统同步机，VSM具有参数多样、易波动和集群动态耦合等新特性，导致微电网内振荡模式复杂多变。针对含高比例VSM的微电网宽频带耦合振荡问题，项目首先研究计及分布式电源输出特性的VSM参数摄动原理，提出VSM真实惯量和阻尼的辨识方法；其次，研究微电网宽频带耦合振荡机理，提出动态过程的数学描述方法；最后，建立宽频带振荡模型，提出不稳定状态判定方法和行之有效的振荡抑制措施。项目的研究成果有利于解决含高比例VSM的微电网复杂振荡问题，为VSM大规模应用提供基础理论支撑，促进新能源消纳。

虚拟同步机（virtual synchronous machine, VSM）可解决分布式电源惯量和阻尼缺失问题，在微电网中得到了大规模应用，但同时也给微电网带来了高频振荡新问题，影响微电网运行稳定性。本项目揭示了含高比例VSM 的微电网宽频带耦合振荡机理，建立了系统数学模型，并提出振荡判断方法和振荡抑制方法。提出了VSM模型降阶分析方法，改进sum-范数判据和幅频特性曲线的稳定性分析方法，基于虚拟电流的VSM预同步控制策略，引入暂态电磁功率补偿的VSM与系统模型降阶方法，基于滑模控制的低频振荡抑制方法，为提高微电网运行稳定性提供有效的理论分析方法和实施措施。项目研究成果一方面有利于解决多VSM系统精准建模问题，为含高比例VSM的微电网宽频耦合振荡分析提供理论基础；另一方面为揭示其复杂振荡机理提供有效的数学分析方法，从而解决振荡抑制的难题。本项目研究结论可直接应用于风力发电、光伏发电、储能系统和电动汽车充电桩等电力电子变换器控制，大大提高含高比例虚拟同步机的微电网可控性、稳定性、安全性和可靠性，还可推广应用于主动配电网、虚拟发电厂、小型区域电网等各类型电力系统中，为电力系统的安全、稳定运行提供重要技术支撑。