多端柔性直流输电系统直流电压混合控制策略

Research of DC Voltage Hybrid Control Strategy for VSC-MTDC System

多端柔性直流输电系统的直流电压协调控制主要有直流电压偏差法和直流电压斜率法。直流电压偏差法在控制模式切换时存在较大的直流电压波动,而直流电压斜率法的有功潮流不能精确控制。针对现有方法的缺陷,提出一种直流电压混合控制策略,设计4阶混合控制器结构,阐述混合控制器配置原则和降阶变结构方法,最后搭建典型的三端柔性直流输电系统进行了仿真验证,证明了直流电压混合控制策略的直流电压接管更加平稳,并可以实现有功潮流的精确控制。

DC voltage margin （DCVM） and DC voltage droop （DCVP） are the main DC voltage coordinate control strategies for voltage source converters in multi-terminal high voltage DC transmission（VSC-MTDC） system. For DCVM, a DC voltage ripple occurs when control mode change, and for DCVP, the active power flow cannot be concisely controlled. To solve these problems, a DC voltage hybrid control（DCVHC） strategy is proposed in this paper, and a 4-stage DCVHC structure is designed, the configuration principles and the reduced stage methods for variable structures are expounded, also a typical three terminals VSC based high voltage DC transmission system（VSC-HVDC） is built for simulation and performance comparison. With DCVHC, the DC voltage ripple is reduced, the active power flow concisely control is also achieved.