LCC-MMC串联型混合直流输电系统小信号建模

Small-Signal Modelling of LCC-MMC Series Hybrid HVDC Transmission System

该文建立了整流侧为电网换相换流器(LCC)、逆变侧为LCC和模块化多电平换流器(MMC)串联的LCC-MMC串联型混合直流输电系统的小信号模型。首先,推导LCC的交直流侧等效电路和考虑内部动态特性的MMC的交直流侧等效电路;然后,基于等效电路构建系统整流侧模型和逆变侧模型,并对直流输电线路和控制系统进行建模,通过组合各个部分模型得到全系统模型;最后,通过线性化全系统模型得到全系统小信号模型。通过对比基于PSCAD/EMTDC搭建的电磁暂态模型验证小信号模型的准确性;基于小信号模型,分析MMC定直流电压控制参数、逆变侧LCC定直流电压控制参数、锁相环(PLL)参数和交流联络线参数对系统小信号稳定性的影响。该文所提出的LCC-MMC串联型混合直流输电系统的小信号模型可用于系统的小信号稳定性分析,从而为系统设计和参数选择提供有价值的参考。

This paper establishes the small-signal model of LCC-MMC series hybrid HVDC transmission system,which rectifier side is LCC and which inverter side is series connect of LCC and MMC.Firstly,equivalent circuits of the AC and DC sides of LCC and equivalent circuits of the AC and DC sides of MMC considering internal dynamic characteristics are derived.Then,models of the rectifier and inverter sides of the system are constructed based on equivalent circuits.By combining each part of the above,consisting of the DC line and control system,the entire system's model is obtained.Finally,the small-signal model of the entire system is obtained by linearizing the entire system's model.The accuracy of the small-signal model is verified by comparing the electromagnetic transient model based on PSCAD/EMTDC.The influences of the constant DC voltage control parameters of MMC and LCC in the inverter-side,PLL parameters,and the tie line parameters on the small-signal stability of the system are analyzed based on the small-signal model.The small-signal model of LCC-MMC series hybrid DC transmission system proposed in this paper can be used for the system's small-signal stability analysis,thereby providing a valuable reference for system design and parameter selection.