摘要
采用柔性直流输电作为电磁环网的解环方案,能有效解决电磁环网诸如正常运行时潮流分配不灵活、短路电流过大、故障后潮流转移导致电压及功角失稳等问题,但当主变高压侧发生N-2故障后仍然存在孤网运行频率失稳的风险。对于故障后导致有功不平衡量较大的孤网,由于其旋转惯量较小,单一负荷及机组占总体容量比例较高,传统稳定控制策略难以维持孤网稳定运行。该文提出一种柔性直流应用于电磁环网的故障孤网稳定控制方法,该方法设计柔性直流调节与稳定控制二、三道防线的动作配合时序,并进一步提出一种自适应高频切机/低频切负荷与柔性直流调节的协调控制策略。结合时域仿真分析,验证所提出的协调控制方法能实现二、三道防线之间的协调配合,且有效维持故障后孤网的频率稳定。
Using VSC-HVDC to break up the electromagnetic loop network can effectively avoid problems of electromagnetic loop network, such as the inflexibility of the power flow distribution, the large current of short circuit, and the voltage and phase instability caused by the power flow transfer after fault. Nevertheless, when the N-2 fault happens at the high voltage side of the main transformer, there are still risks of frequency instability of isolated power grids. For the isolated power grid with a large degree of power imbalance, the isolated power grid cannot operate steadily with traditional control strategies as its small rotary inertia and a higher proportion of single loads or generators. This paper presents a supplementary control method for electromagnetic loop networks based on VSC-HVDC. A coordinated action sequence is designed for stability control of VSC-HVDC as well as the 2 nd and 3 rd defense lines. And a coordination control strategy is presented for over-frequency generator tripping/low-frequency load shedding combined with the VSC-HVDC control. The time domain simulation shows that the proposed control strategy can help the cooperation between the 2 nd and 3 rd defense lines, resulting in a frequency stability of isolated power grids after faults occur.
作者
时伯年
孙刚
瞿艳霞
SHI Bo-nian;SUN Gang;QU Yan-xia(Beijing Sifang Automation Co.Ltd.,Beijing 100085,China)
出处
《电力科学与技术学报》
CAS
北大核心
2019年第4期137-142,共6页
Journal of Electric Power Science And Technology
关键词
柔性直流输电
稳定控制
高频切机
低频切负荷
VSC-HVDC
stability control
over-frequency generator tripping
under-frequency load shedding
