基于固有频率的海上风电接入柔直系统的交流送出线路纵联保护原理  

A novel pilot protection for AC transmission lines of VSC-HVDC connected offshore wind farms based on natural frequency

作　　者：戴志辉[1] 韩哲宇 李杭泽 DAI Zhihui;HAN Zheyu;LI Hangze(State Key Laboratory of Alternate Electrical Power System with Renewable Energy Resources,North China Electric Power University,Baoding 071003,China;Chengxi Power Supply Branch,State Grid Tianjin Electric Power Company,Tianjin 300110,China)

机构地区：[1]新能源电力系统全国重点实验室(华北电力大学),河北保定071003 [2]国网天津市电力公司城西供电分公司,天津300110

出　　处：《电力系统保护与控制》2025年第5期35-46,共12页Power System Protection and Control

基　　金：河北省自然科学基金项目资助(E2024502043)。

摘　　要：当海上风电交流送出线路发生不对称故障时,因线路两侧换流器均采用负序抑制控制策略,负序网络中电容电流影响不可忽略,传统纵联差动保护可靠性降低。为此,首先阐述了海上风电柔直送出系统结构,并通过送出线路两侧电力电子设备控制策略分析其故障特征。其次,考虑电容电流分析纵差保护适应性和固有频率差动保护盲区问题。在此基础上,利用海上模块化多电平换流器侧母线负序电压及线路两侧电流正序分量之和构造出表征位置的变量λ,并利用λ构造保护辅助判据。最后,基于PSCAD/EMTDC搭建海上风电系统模型,分析并验证所提保护方案的有效性。结果表明,所提方法可靠性高、动作速度快,能耐受20 dB噪声和100Ω过渡电阻。When asymmetric faults occur in the AC transmission lines of offshore wind networks,the reliability of traditional differential protection is reduced because of the effect of capacitive current in the negative sequence network,as the converters on both sides of the line adopt negative sequence suppression control strategies.To address this issue,this paper first outlines the structure of the offshore wind power transmission system and analyzes the fault characteristics through the control strategies of power electronic equipment on both sides of the transmission line.Considering capacitive current,the adaptability of longitudinal differential protection and the blind area of natural frequency differential protection are then evaluated.On this basis,using the negative sequence voltage of the offshore MMC busbar and the sum of the positive sequence currents on both sides of the line,a location-indicating variableλis constructed and is further used to construct an auxiliary protection criterion.Finally,an offshore wind power system model is built in PSCAD/EMTDC to analyze and verify the effectiveness of the proposed protection scheme.The results show that the proposed method exhibits high reliability,fast response,and can tolerate 20 dB noise and 100Ωfault resistance.

关 键 词：海上风电 交流送出线路 纵联保护 固有频率 负序电压 

分 类 号：TM614[电气工程—电力系统及自动化] TM721.1TM773