多VSC系统有功功率–频率动态的电路建模方法

Circuit Modeling Method of Active Power-frequency Dynamics for Multiple-VSC Systems

包含不同类型电压源变流器(voltage-source converter,VSC)的多机系统在各种干扰期间易发生暂态功率环流和功频振荡现象。为了简化多VSC系统有功功率-频率动态特性分析,文中基于机械导纳法构建描述VSC有功功率-频率动态的电路模型。根据机电比拟原理,构建单台同步发电机(synchronous generator,SG)/VSC的电路模型框架,并推导9种典型VSC控制的电路模型参数。以VSC四机系统为例,构建其电路网络模型,并从模型比较、频域特性和仿真分析3方面验证所建模型的准确性和有效性。电路建模法的优点是不仅可推导出不同类型扰动下的详细传递函数,而且对不同类型VSC控制策略均适用。基于该模型,可采用电路理论分析多VSC系统的有功功率-频率特性,为多VSC动态特性分析提供了一种新思路。

For the modern power systems with high penetration of voltage source converters(VSCs), it is easy to cause transient power circulation and power-frequency oscillation between VSCs following different types of disturbances. To simplify the analysis of active power-frequency dynamics for multiple-VSC systems, a circuit model describing the active power-frequency dynamics of VSC was constructed based on mechanical admittance. According to the electromechanical analogy principle, the modeling framework of synchronous generators(SGs)/VSCs was constructed, and the circuit model parameters of nine VSC control strategies were deduced. Taking a four-VSC system as an example, the circuit network model of the system was constructed. The accuracy and effectiveness of the proposed model were verified by model comparison, frequency domain characteristics and simulation analysis. The circuit model can be used to derive the detailed transfer functions of multiple-VSC systems under different types of disturbances,and it is applicable to a variety of VSCs. Based on this model,the torque-frequency characteristics of multiple-VSC systems can be analyzed and designed by the circuit theory, which provides a new idea for the analysis of VSC dynamic.