向孤岛电网供电的柔性直流逆变站综合控制策略

考虑孤岛电网存在有源电网状态和无源电网状态之间的状态变化,文中提出了向孤岛电网供电的柔性直流逆变站综合控制策略,以实现在孤岛电网状态变化时保证对其可靠供电。从柔性直流的控制原理出发,分析了有源电网和无源电网下柔性直流逆变站控制方式的差别。当孤岛电网从有源电网变为无源电网,向其供电的柔性直流逆变换流站控制方式切换时,文中从稳定交流电压和快速恢复有功平衡考虑,提出了相角跟随和有功功率优先2个控制策略,以保证切换时刻孤岛电网和直流系统的各电气量波动最小。建立柔性直流输电系统的PSCAD/EMTDC仿真模型,仿真验证了文中控制策略的有效性,在孤岛状态变化时可实现持续可靠供电。

Integrated control strategy of VSC inverter supplying power to the isolated grid

Considering the isolated power grid state changing between active power grid and passive power grid, an integrated control strategy is proposed for VSC station to supply power to isolated power grid. Based on the principle of VSC control, the difference of control modes of VSC-HVDC inverter in active and passive power grids is analysed. When isolated power grid changes from active power grid to passive power grid, the control mode of VSC station changes. Considering the stabilization of AC voltage and fast restoration of active power balance, two control strategies, angle following and active power priority, are proposed in the paper. A comprehensive control system is designed to ensure the minimum fluctuation of each electrical quantity of islanded power grid and DC system at the time of switching. The PSCAD/EMTDC simulation model of VSC-HVDC transmission system is established. The simulation results verify the validity of the integrated controller and control strategy proposed in this paper. The continuous and reliable power supply can be realized when the isolated grid state changes.