静止无功补偿器在青藏直流工程中的应用

Application of Static Var Compensator in Qinghai-Tibet HVDC Project

拉萨换流站弱系统连接导致所用的无功补偿设备容量较小,数量较多,引起投资增加,为此,建立了带有静止无功补偿器(SVC)的青海—西藏(青藏)交直流工程PSCAD仿真模型,仿真各种直流运行方式、各水平年下不同容量无功设备投切引起的电压波动,以寻找满足要求的无功补偿分组设置。通过大量的仿真,确定了该期无功设备分组容量及远期分组容量,同时得到以下结论:直流系统带有SVC,不但可以使无功设备容量大幅增加,而且能够满足无功补偿投切引起的电压波动要求。最后,通过PSCAD仿真确定了SVC的控制策略。将所得研究结果应用于青藏直流工程,由于安装了SVC,无功分组的容量由每组25 MVA提高到45 MVA,在投切滤波器时,换流母线的暂稳态电压波动也满足无功导则的要求,表明制定的SVC控制策略提高了工程运行的可靠性和安全性。工程实际运行情况证明了研究结果的正确性和可行性,对今后直流工程的设计和研究具有较大的参考价值。

The weak ac system connection of Tibet Power Grid leads to small capacity and more installed number of reactive power compensation apparatus, which will cause increasing investment, thus we established a simulation model of Qinghai-Tibet ac and dc systems with static var compensator（SVC） by PSACD to calculate voltage fluctuation caused by switching reactive power compensation apparatus of different capacity under different operation modes and in different years, so as to figure out suitable reactive power compensation arrangement. Meanwhile, we determined the reactive power capacity of sub-bank for the near term and the future term by plenty of simulation. It is concluded that, the capacity of sub-bank increases from the original 25 MVA to 45 MVA and the temporary steady-state voltage fluctuation of commutation bus can meet the requirements of reactive power guide, indicating that the strategy improves stability and safety of the project. The actual operation situation proves validity and feasibility of the proposed strategy, which provides a reference for future HVDC project design.