基于VSC-HVDC的风电分散并网下垂控制策略

海上风电的大规模开发使得柔性直流(VSC-HVDC)输电技术得到了越来越广泛的关注与应用。文中通过引入交流电压下垂控制,提出了基于VSC-HVDC的适应送端交流分散模式下的风电场多端并网的协调控制策略。在柔性直流输电传统控制策略的基础上,保留配电网侧逆变器的定直流电压控制,以保证系统功率平衡;而使风电场侧整流器采用交流电压下垂控制,以代替原有的恒功率控制,从而引入下垂控制的无需通信联系和合理动态分配等优势。仿真分析表明所提控制策略不仅能保证有功出力灵活自动跟踪系统额定值,而且还具有一定的负荷波动容忍度和交直流故障隔离功能,且在风电场采用送端交流分散模式同时向多端配电网供电时,能在风电机组切出系统的情况下快速实现潮流反转,以保证系统供电可靠性,并能自动按照额定比例在各配电网间合理分配动态功率,为风电分散并网的协调运行提供了有效的解决途径。

Droop Control Strategy for Wind Power Decentralized Integration Based on VSC-HVDC Systems

With the large-scale development of offshore wind power, the voltage source converter based high voltage direct current(VSC-HVDC)transmission system has received extensive attention in recent years. By introducing the AC voltage droop control, a coordinated multi-terminal grid-connection control strategy for a wind farm AC-dispersed at the sending end based on VSC-HVDC systems is proposed. Based on the traditional control strategy for the flexible HVDC transmission system, the DC voltage control of inverters on the grid side is retained to guarantee system power balance, while AC voltage droop control rather than the original constant-power control is designed for the rectifier on the wind farm side to achieve the advantage of communication-free and reasonable dynamic allocation. Simulation analysis shows that the control strategy proposed is not only able to achieve flexible automatic tracking of rated active power, but also has certain tolerance of load fluctuation and the function of DC/AC fault isolation. And when it comes to power supply for multi-terminal distribution networks by a wind farm AC-dispersed at the sending end, quick power reversal can be achieved if the wind farm is cut out of the system to ensure power supply reliability. And the system is capable of realizing rational allocation of dynamic power automatically among them according to rated ratio, providing effective solutions for coordinated operation of wind farm's decentralized integration into distribution networks. This work is supported by State Grid Corporation of China(No. 5211011400BT).