交流电流控制尺度下的并网VSC聚合建模研究

Research on Aggregation Modeling of Grid Connected VSC Under AC Current Control Scale

随着电力系统的电力电子化程度逐年提高,越来越多新能源电源(如风电、光伏等)经由电压源型换流器(voltage source converter,VSC)接入交流电网,新能源场站与电网的动态交互引发了多起新型次同步振荡事件,对电力系统安全运行构成严重威胁。为了研究新能源场站与电网之间的相互作用,若采用“自下而上”的方法对场站每一台VSC都进行详细建模,将面临“维数灾”问题,分析结果难以认知。因此,研究新能源场站的动态等值建模理论十分必要。文中提出一种基于结构保持的并网VSC聚合建模方法,分析并网VSC引发次同步振荡问题主要与交流电流控制尺度相关,据此建立并网VSC交流电流控制时间尺度下的聚合模型,模型适用于并网VSC在交流电流控制时间尺度下的小干扰稳定性分析,能够反映风电场的整体特性与内部单个风机特性之间的关系,通过仿真验证聚合模型的有效性。

With the improvement of power electronics of power system year by year, more and more new energy sources(such as wind power, photovoltaic, etc.) have been connected to AC power grid through VSC. The dynamic interaction between new energy stations and power grid has triggered many new Sub-synchronous Oscillation events, which poses a serious threat to the safe operation of power system. When studying the interaction between new energy stations and power grid, the “bottom-up” method used for modelling each VSC in the station may cause the problem of “dimension disaster”, and the analysis results are difficult to recognize.Therefore, it is necessary to study the dynamic equivalent modeling theory of wind farm. This paper proposed an aggregation modeling method of grid connected VSC based on structure preservation. The sub-synchronous oscillation caused by grid connected VSC was analyzed, which is mainly related to the AC current control scale. The aggregation model of grid connected VSC under the AC current control time scale was established, which is suitable for the small signal stability analysis of grid connected VSC under the AC current control time scale, reflecting the relationship between the overall characteristics of the wind farm and the characteristics of a single internal fan. The simulation verifies the effectiveness of the aggregation model.