混合级联特高压直流输电线路纵联差动保护适应性分析
Adaptability Analysis of Pilot Differential Protection for Hybrid Cascaded UHVDC Transmission Lines
牟大林 1林圣 1李小鹏2
作者信息
- 1. 西南交通大学电气工程学院,四川省成都市 611756
- 2. 国网四川省电力公司电力科学研究院,四川省成都市 610041
- 折叠
摘要
为探究现有高压直流输电线路纵联差动保护对混合级联特高压直流输电系统的适应性,结合混合级联特高压直流输电系统的运行方式,理论分析和仿真分析3种特殊运行方式下直流系统不同位置故障的故障特性和保护适应性.理论分析发现纵联差动保护适应性较好.仿真分析发现直流线路分布电容和逆变侧模块化多电平型换流器(modular multilevel converter,MMC)控制特性影响在直流线路故障时直流线路电流延时自减值长时间处于波动状态,导致纵联差动保护长时间处于闭锁状态,此时,系统长时间承受MMC超大故障电流冲击.直流线路区外故障时整流侧与逆变侧直流电流差值的绝对值数值较大且长时间处于波动变化状态,纵联差动保护存在误动的风险.
Abstract
To explore the adaptability of the existing pilot differential protection for the dc lines to the hybrid cascaded ultra-high-voltage direct current(UHVDC)transmission system,combined with the operation modes of this system,the fault characteristics and protection adaptability of the dc system faults at different locations under three special operating modes are analyzed by theoretical analysis and simulation.The theoretical analysis shows that the pilot differential protection is good in adaptability.The simulation analysis shows that the DC line distribution capacitance and the modular multilevel converter(MMC)control characteristics of the inverter side may cause the dc line current delayed self-decrement to fluctuate for a long time during a DC line fault,resulting in a very long lockout duration of the pilot differential protection.Currently,the system suffers the super fault current impact of the MMC for a long time.When there is a failure outside the DC line area,the DC current difference between the rectifier side and the inverter side may have a large absolute value and be in a fluctuating state for a long time,existing a risk of incorrect operations in the pilot differential protection.
关键词
混合级联特高压直流输电系统/纵联差动保护/适应性分析/运行方式/保护误动Key words
hybrid cascade UHVDC transmission system/pilot differential protection/adaptability analysis/operation mode/protection mis-operation引用本文复制引用
出版年
2024
国家科技期刊平台
NSTL
维普
万方数据