多类型故障影响下柔直线路故障机理分析及单端保护方法

doi:10.11930/j.issn.1004-9649.202404004

摘要/Abstract

摘要：

多端柔性直流输电线路保护存在多种故障类型，易受过渡电阻、噪声等因素的影响。为此，提出一种应用单端电压梯度能量值的柔直线路全线速动保护方法，仅基于单端测量电压即可保护线路全长。分析了柔性直流线路区内外的电压故障特征，并引入改进电压梯度算法构建保护启动判据，进一步构建基于能量值比较的全线故障保护判据，基于正负极能量比在单极或极间故障下所处范围不同实现故障选极。仿真验证表明：所提方法能够快速完成区内外故障识别、故障极判断，并具有良好的抗噪性和耐高阻能力。

关键词: 柔性直流线路, 单端保护, 改进电压梯度, 故障区判别

Abstract:

Multi-terminal flexible DC transmission line protection faces various fault types and is susceptible to factors such as transition resistance and noise. To address this, a fast-action protection method for the entire flexible DC line using single-ended voltage gradient energy values is proposed, which can protect the entire length of the line based solely on single-ended measured voltage. The voltage fault characteristics inside and outside the flexible DC line are analyzed, and an improved voltage gradient algorithm is introduced to construct a protection initiation criterion. Furthermore, a full-line fault protection criterion based on energy value comparison is constructed, and fault pole selection is achieved based on the different ranges of positive and negative energy ratios under unipolar or inter-pole faults. Simulation verification shows that the proposed method can quickly identify faults inside and outside the zone, determine the fault pole, and exhibits good noise immunity and high resistance tolerance.

Key words: flexible DC line, single-ended protection, improved voltage gradient, fault zone identification

中图分类号:

TM733

慕宗君, 邱俊宏, 李振兴, 王卫东, 刘登鑫, 胡斌. 多类型故障影响下柔直线路故障机理分析及单端保护方法[J]. 中国电力, 2025, 58(1): 107-114.

Zongjun MU, Junhong QIU, Zhenxing LI, Weidong WANG, Dengxin LIU, Bin HU. Fault Mechanism Analysis and One-terminal Protection Method of Flexible DC Transmission Line under the Influence of Multi-type Faults[J]. Electric Power, 2025, 58(1): 107-114.

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链接本文: https://www.electricpower.com.cn/CN/10.11930/j.issn.1004-9649.202404004

https://www.electricpower.com.cn/CN/Y2025/V58/I1/107

图/表 10

图 1 四端MMC输电系统

Fig.1 The transmission system of four-terminal MMC

图 2 区外正极接地故障电压梯度能量值

Fig.2 Voltage gradient energy value of positive grounding external fault

表 1 张北四端直流输电线路参数

Table 1 Transmission line parameters of Zhangbei four-terminal flexible DC transmission

MMC	额定容量/ MW	额定直流电压/ kV	桥臂电感/ mH	平波电抗器/ mH	子模块电容值/ mF	单桥臂子模数/ 块	交流侧线电压/ kV
MMC1	1500	500	75	200	10	200	330
MMC2	1500	500	75	200	10	200	330
MMC3	3000	500	75	200	10	200	330
MMC4	3000	500	75	200	10	200	330

图 3 正极接地故障电压梯度值

Fig.3 The voltage gradient value is when the positive grounding faults

图 4 F3正极金属性接地故障

Fig.4 Positive metal grounding fault at F3

图 5 F3极间金属性接地故障

Fig.5 The inter-pole metallic grounding fault at F3

图 6 F3负极金属性接地故障

Fig.6 The negative metallic grounding fault at F3

图 7 F3正极经700 Ω过渡电阻接地

Fig.7 A 700 Ω resistance grounding positive fault at F3

表 2 区外故障仿真结果

Table 2 Simulation results of multiple external faults

故障类型	故障位置	E_P/kV²	E_N/kV²	判断结果
正极接地	F₄	3.327×10⁴	5656	区外正极
正极接地	F₁₂	3.061×10⁴	4500	区外正极
负极故障	F₄	5607	3.039×10⁴	区外负极
负极故障	F₁₂	4067	3.097×10⁴	区外负极
极间故障	F₄	2.979×10⁴	3.146×10⁴	区外极间

图 8 电压故障分量相似度法

Fig.8 Current fault component similarity method

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