大规模新能源经张北柔直孤岛送出的虚拟频率研究

大规模新能源经柔性直流送出为解决新能源并网消纳提供了一种新的思路,但是在不加任何附加控制的情况下,新能源的有功波动会经过柔直全部传递到受端电网。为了解决新能源经柔直并网的有功波动问题,文中针对张家口地区的大规模新能源发电经张北柔直换流站孤岛送出系统的风电运行数据进行分析,得出该地的风电短时波动特性。同时在孤岛换流站的电压-频率(VF)控制基础上,设计换流站虚拟频率控制策略,与新能源发电一次调频(PFR)控制一起实现孤岛换流站的功率波动自主抑制功能。最后搭建大规模风电经单端柔性直流孤岛送出系统仿真平台,仿真结果证明,在风机运行状态正常的前提下设计的虚拟频率及一次调频控制方案可以,较好地实现孤岛换流站功率波动抑制。

Virtual frequency control of islanded large-scale renewable energy power system delivered by Zhangbei VSC-HVDC

Voltage source converter based high voltage direct current(VSC-HVDC) provides a new way to solve grid-connected accommodation problem of renewable energy. However, the active power fluctuation of renewable energy will be transmitted to receiving-end power grid through VSC-HVDC under no additional control. In order to solve active power fluctuation problem of renewable energy grid-connected through VSC-HVDC, an islanded large-scale renewable energy power system in Zhangjiakou area which delivered by VSC-HVDC is studied. The short-time power fluctuation characteristic of wind farms in this area is obtained by actual operation data analysis. A virtual frequency control strategy is designed on the basis of voltage frequency(VF) control in an islanded VSC station. Thus,the active regulation of power fluctuation function can be realized by proposed virtual frequency control in VSC station and primary frequency regulation(PFR) in renewable power generation. Finally, a simulation platform of large-scale wind power delivered by single terminal VSC-HVDC is built. Simulation results testify that the power fluctuation is well regulated by proposed virtual frequency control cooperated with the PFR control in terms of wind power generation operated normally.