大型风电场经VSC-HVDC交直流并联系统并网的运行控制策略

Control Strategies of Large Wind Farms Integration Through AC/DC Parallel Transmission System Based on VSC-HVDC

基于电压源换流器高压直流输电(voltage source converter based HVDC,VSC-HVDC)的直流系统存在与交流线路并联运行的情况。交直流系统之间相互切换的运行工况复杂,且切换过程存在切换依据难以确定、切换冲击大以及通信延时等问题。为解决该问题,在分析VSC-HVDC工作原理、数学模型及其控制策略的基础上,提出了一种大型风电场经VSC-HVDC交直流并联系统并网的运行控制策略,该策略在不改变换流站控制方式的情况下,可实现交直流并联系统运行方式的无缝切换。基于MATLAB/Simulink仿真软件,建立了系统仿真模型,对交直流并联系统稳态运行及动态切换过程进行了仿真分析。仿真结果表明,所提出的控制策略能够较好地实现交直流并联系统有功功率的精确分配和运行方式的无缝切换,算法简单,可靠性高。

The operation condition switching between DC transmission and AC transmission exists in AC/DC parallel system based on VSC-HVDC. However, the main issues are complex operation conditions, uncertain switching criterion, serious switching impact, communication delay and so on. To solve these problems, the operation and control scheme of wind farm grid integration with AC/DC parallel transmission system based on VSC-HVDC was proposed, on the basis of analysis of VSC-HVDC operation principle, mathematical models and control strategies. This scheme can realize seamless switching of operation conditions in AC-DC parallel transmission system without changing the control method of the VSC stations. The system model was established based on MATLAB/Simulink simulation software. The steady-state operation and dynamic switching process of AC/DC parallel transmission system were evaluated by the simulation results. The simulation results show that precise active power distribution and seamless operation condition switching can be well achieved in AC/DC parallel transmission system by the proposed control strategy with simple algorithm and good reliability.