基于高阶系统模型的VSC-MTDC下垂控制策略研究

摘要

Voltage Source Converter based Multi-terminal Distribution (VSC-MTDC) is based on flexible-HVDC and multi-stations coordinated control strategy. First,P-Udc/Uac-Q droop strategy and control system architecture are designed. Then, based on LCL high-order primary system model, control system architecture of inner current loop, outer DC-voltage loop and droop loop is proposed, and a design method of optimized control parameter is made. Finally, simulation model of 4-terminal 10 kV VSC-MTDC is built and control parameters are selected. Starting control, steady-state control and critical step response are analyzed. Simulation results show that adopting the proposed control strategy, each converter could achieve droop control of active power flow upon maintaining stability of DC bus voltage. Security and stability of VSC-MTDC is improved and response characteristics are good upon multi transient conditions.%多端柔性直流输电(VSC-MTDC)基于柔性直流技术及多站协调控制策略.首先,设计了适于VSC-MTDC的P-Udc/Uac-Q下垂策略及控制系统架构.其次,提出基于LCL高阶一次系统模型的电流内环、直流电压外环及下垂环控制器架构,并形成了优化控制参数的设计方法.最后,在PSCAD/EMTDC中搭建了10 kV 4端VSC-MTDC的仿真模型并进行控制参数优化,基于启动控制、稳态控制及临界阶跃响应3种暂态工况进行仿真分析.仿真结果表明,所提策略可实现各站直流母线电压的独立控制基础上的下垂式有功潮流控制,提升了VSC-MTDC系统的安全稳定性,且多种暂态工况下响应特性良好.