考虑静止无功补偿器的直驱风电并网系统次同步振荡

Sub-synchronous oscillation in wind farm integrated power system considering static var compensator

近年来频发的风电场次同步振荡事故极大影响了电网的安全稳定运行。考虑到无功补偿设备在风电场中的广泛应用,基于变流器控制的风电场可能会与其发生耦合作用导致系统失稳,故该文研究了考虑静止无功补偿器(SVC)的直驱风电并网系统次同步振荡。首先,基于SVC的时域仿真模型与频率扫描法,分析SVC在次同步频段的阻抗频率特性。进一步建立考虑SVC的风电并网系统的状态空间模型,计算系统特征模态和模态参与因子,分析SVC与直驱风电场间的次同步相互作用。分析结果表明,SVC在次同步频段将削弱风电并网系统阻尼,增加系统振荡风险;SVC与直驱风电场间存在明显的次同步相互作用,将导致系统发生次同步振荡,振荡特性与交流网络强度及风电场、静止无功补偿器的控制参数相关。时域仿真验证了该分析结果。

Recently,the long-standing sub-synchronous oscillation(SSO)in wind farms has greatly affected the operation of power systems.Large-scale wind farms comprise various types of wind turbine generators(WTGs)and dynamic reactive power compensation devices,further increasing the complication.Based on the practical phenomenon for further study,this paper focuses on the interactions among the direct-drive permanent synchronous generator(D-PMSG)-based wind farm,static var compensator(SVC),and connected grid.First,the impedance-frequency characteristics of SVC are studied based on the time-domain model of SVC and the frequency scanning method.Moreover,a state-space model of the D-PMSG-based wind farm equipped with an SVC is established to calculate the modes and their participation factors.The sub-synchronous interaction between the SVC and the D-PMSG-based wind farm will then be observed.Results indicate that the SVC may weaken the damping of the wind farm integrated power system and increase the risk of SSO.Furthermore,there is an obvious interaction between the SVC and the D-PMSG-based wind farm,which will lead to oscillation.System strength and control parameters of the SVC and D-PMSG-based wind farms can influence the oscillation characteristics.Theoretical results are verified by simulation.