考虑电压前馈控制的MMC-HVDC并网稳定性分析及其阻抗控制优化方法

MMC-HVDC Integrated System Stability Analysis and Impedance Optimization Method With Consideration of Voltage Feed-forward Control

为抑制上千赫兹的高频振荡,柔性直流工程中常在基于模块化多电平换流器(modular multilevel converter,MMC)的高压直流输电(high voltage direct current,HVDC)控制环路中加入基于低通滤波器的电压前馈控制,然而,电压前馈控制对MMC-HVDC并网站阻抗特性影响较大,在某些工况下,加入电压前馈控制对系统稳定性会有恶化作用,因此,有必要深入研究考虑电压前馈的MMC-HVDC并网稳定性及其阻抗优化控制方法。文中采用多谐波线性化方法,建立考虑电压前馈控制的MMC-HVDC并网站序阻抗模型,采用阻抗灵敏度分析方法,解析MMC-HVDC并网站不同控制环路对系统稳定性的影响作用能力,系统分析考虑电压前馈控制对准确分析并网系统稳定性问题的必要性及其用以提升系统稳定性的有效性,在此基础上,提出一种基于电压前馈控制的MMC-HVDC并网站阻抗控制优化方法,实现了并网系统稳定性的有效提升。在Matlab/Simulink中搭建考虑电压前馈控制的MMC-HVDC并网站仿真模型,对其序阻抗模型、并网稳定性分析及阻抗优化与重塑方法进行验证。

In order to suppress high frequency resonance,low-pass filter-based voltage feedforward controllers are commonly used in MMC-HVDC projects.Voltage feedforward control may have negative impacts on MMC-HVDC integrated system stability.Therefore,it is worth analyzing the impacts of feedforward control on impedance characteristic as well as integrated system stability.First,the multi-harmonic linearization method is adopted to establish the MMC-HVDC sequence impedance model considering voltage feedforward control.Then,the impedance sensitivity analysis method is used to quantify the impacts of different controllers on the stability of integrated system.Voltage feedforward control is essential in integrated systems stability analysis and in system stability improvement.Finally,an optimization method for MMC-HVDC impedance control based on voltage feedforward control is proposed to improve the stability of integrated system.The accuracy of the sequence impedance model and the effectiveness of impedance optimization method proposed in this paper are verified in Matlab/Simulink.