基于动态相量法的改进多端模块化多电平换流器HVDC小干扰稳定模型

针对含多端模块化多电平换流器高压直流(MMC-HVDC)交直流混联系统的稳定问题,提出一种基于动态相量法的改进小干扰稳定分析模型。由于传统小干扰稳定模型均基于准稳态假定,因此难以反应电力电子型器件的快速动态过程。综合考虑多端MMC-HVDC有源及无源网络下的控制策略,推导并建立基于动态相量法的改进小干扰模型。建立含海上风电场的多端MMC-HVDC测试系统,并对比分析电磁暂态模型、传统小干扰模型及改进小干扰模型在动态响应下的精度及仿真时间。根据仿真结果,所提改进小干扰模型能够较好地跟随系统动态响应,预测系统振荡过程,并能显著削减仿真时间,其有效性和适应性得到了证明。

Advanced Small-Signal Stability Model for Multi-Terminal Modular Multilevel Converter-HVDC Systems Based on Dynamic Phasors

This paper proposes an advanced small-signal stability model for multi-terminal MMC-HVDC systems based on dynamic phasors and state-space. As ignoring the dynamic process of converter, the traditional models based on quasi-steady state assumption are difficult to reflect the rapid dynamic process of electronic devices. In accordance with active and passive network control strategies for multi-terminal MMC-HVDC, the small-signal stability models based on dynamic phasors are conducted, and related theoretical derivation is carried out. From the simulation analysis of a typical multi-terminal MMC-HVDC network with offshore wind generation and conventional power sources, the comparisons among the advanced small-signal model, electromagnetic-transient model and traditional small-signal state-space model are performed. It is shown that, the advanced small-signal state-space model can successfully follow the electromechanical transient response with small errors, predict the damped oscillations, and reduce the whole simulation time. Consequently, the validity and applicability of the proposed model are well confirmed.