应对UHVDC送端电网新能源大规模脱网的频率紧急控制

我国特高压直流输电(UHVDC)的快速发展及新能源发电占比的不断提高,有力支撑了国家的能源战略转型。但由于新能源机组的涉网保护性能较差,在新能源集中接入的直流送端电网,发生交直流故障后容易导致新能源大规模脱网,给电网的暂态频率安全保障带来极大挑战。文中首先分析UHVDC送端电网新能源大规模脱网的故障过程;然后针对现有应对新能源脱网措施的不足,根据故障过程特征提出利用直流换相失败等信息作为触发条件的频率紧急控制技术方案及实现方法;最后搭建西北电网的仿真算例,验证了所提方法能有效应对交直流故障引起的新能源大规模脱网,大幅提升送端电网的UHVDC输电能力及新能源消纳。

Emergency frequency control for large-scale disconnection of renewable energy in the UHVDC sending grid

With the promotion and application of UHVDC and the continuous increase of the proportion of renewable energy power generation, it has strongly supported the country"s energy transformation strategy. However, due to the poor network-related protection performance of renewable energy units, in the DC sending power grid where renewable energy is centrally connected, AC and DC faults can easily cause large-scale disconnection of renewable energy, which brings to a great challenge for the grid"s transient frequency security technology. In this paper the failure process of large-scale disconnection of renewable energy from the UHVDC receiving grid is first analyzed. Then the existing measures to deal with the disconnection of renewable energy are discussed. Finally the emergency control technical scheme using the information of DC commutation failure is designed according to the characteristics of the fault process. The simulation in conjunction with the Northwest Power Grid is carried out, conducting an in-depth analysis of the impact of new energy low voltage ride-through, and the effectiveness of the proposed technical scheme and strategy is verified.