集群新能源经柔直孤岛送出换流站的功率越限控制研究

张北地区大规模新能源发电经柔直换流站孤岛送出系统中,送端换流站容量小于纯新能源电源总容量。为确保换流站功率波动不会短时越限,文中设计了功率越限快速控制系统,包括功率越限回降控制系统和紧急虚拟频率控制系统,对换流站功率越限进行有效预控,确保换流站安全。首先,对张北地区新能源发电的运行数据进行分析,得出张北地区新能源有功短时波动特性,通过概率统计确定在某一时间尺度内发生的最大波动速率,为系统参数设计提供支撑。然后,详细介绍功率越限回降控制系统结构、对新能源功率预控控制过程、关键参数整定原则及回降功率的新能源执行站调用原则等。紧急虚拟频率控制系统作为功率越限回降控制系统在通信中断时的备用。最后,在PSCAD/EMTDC电磁暂态仿真平台搭建了换流站主站以及执行站控制器的仿真模型进行验证。

Fast over-limit power control of converter station sending out new energy in island mode through VSC-HVDC

For the multi-terminal HVDC transmission network in a certain area, two planned large-scale new energy power plants send out power through VSC converter station with no embedded power source. Through analyzing the operation data of the new energy generation in this area, the short-term fluctuation of the active power sent out by the VSC converter station is characterized. For the purpose of safety, a fast off-limit power control system is designed to avoid the station power exceeding the rated capacity of the converter station by rapidly reducing the output of new energy power .In addition, emergency virtual frequency control is designed as its backup. PSCAD/EMTDC simulation platform is used to build the simulation model of converter station and the controller of the new energy station, and the power fluctuation can be avoided by comparison.