柔直换流器和应涌流影响特性分析及暂态冲击抑制方法研究

Study on the impact characteristics of inrush currents on flexible HVDC converter and transient impulse suppression methods

摘要

【目的】针对高压柔性直流(柔直)输电系统中和应涌流暂态冲击引发换流器保护动作而停运的问题，【方法】首先阐述和应涌流的产生机理，然后对不同并网电压电流采集控制方式下换流器运行受和应涌流的影响特性进行研究。在此基础上，提出一种基于网侧-阀侧控制模式切换的和应涌流下换流器暂态冲击抑制方法。最后在MATLAB/Simulink软件中搭建实际工程的电磁暂态模型进行仿真验证。【结果】仿真结果表明，不同采集控制方式会显著影响和应涌流下换流器的暂态电气特性。【结论】相比于网侧采集控制方式，所提出的阀侧采集控制方法可大幅降低换流器受和应涌流的扰动影响，换流器桥臂电流峰值和子模块电容电压波动分别减小40%和67%,有助于柔直换流器安全平稳运行。

Abstract

[Objective] In order to address the issue of shutdowns caused by converter protection actions due to inrush currents and transient impulses in high-voltage flexible direct current(HVDC) transmission systems, [Methods] first, the generation mechanism of inrush currents was explained. Then, the impact characteristics of inrush currents on the operation of modular multilevel converter(MMC) under different grid voltages and current collection control method were investigated. Based on this, a transient impulse suppression method for MMC under inrush currents was proposed, which involved switching between the grid-side and valve-side control modes. Finally, an electromagnetic transient model of the actual engineering system was built in MATLAB/Simulink for simulation verification. [Results] The simulation result demonstrated that different collection control method had a significant impact on the transient electrical characteristics of MMC under inrush currents. [Conclusion] Compared to the grid-side control method, the proposed valve-side collection control method significantly reduces the disturbance impact of inrush currents on the converter. The peak current in the converter bridge arm and the voltage fluctuation of the submodule capacitor decrease by 40% and 67%, respectively, which can ensure the safe and stable operation of the flexible HVDC converter.

关键词

柔性直流输电 / 和应涌流 / 模式切换 / 暂态冲击抑制 / 影响因素

Key words

flexible HVDC transmission / inrush current / control mode switching / transient impulse suppression / influence factor

基金资助

国网冀北电力有限公司科技项目(52018K22001C)

国家自然科学基金项目(52207219)