基于双向时域卷积网络的三端混合直流电网后备保护方案

A Backup Protection Scheme for Three-Terminal Hybrid DC Grids Based on BiTCN

中文关键词:三端混合直流输电  线路保护  线模功率特性  双向时域卷积网络

keywords:three-terminal hybrid DC transmission  line protection  line mode power characteristics  BiTCN

中文摘要:为适应三端混合直流输电线路的保护需求，针对现有直流电网后备保护面临的边界元件特性复杂、阈值整定困难等问题，提出一种基于双向时域卷积网络（bidirectional time-domain convolution network，BiTCN）的三端混合直流电网后备保护方案。首先，考虑T区汇流母线及两侧所连输电线路的结构，分析相应故障特性；其次，提取故障时测量处线模功率突变量极性、线模功率高频能量、电压突变量幅值差异构造故障特征量；最后，将故障特征量、故障类型分别作为BiTCN的输入量、输出量，构建基于BiTCN的线路保护判据。通过搭建特高压三端混合直流输电模型进行仿真验证，结果表明，所提出的保护能识别全线范围的故障，且能够耐高阻，兼具可靠性与速动性。

Abstract:To address the protection requirements of three-terminal hybrid DC transmission lines，a backup protection scheme for three-terminal hybrid DC grids based on the bidirectional time-domain convolution network （BiTCN） is proposed. This scheme aims to solve the problems of complex boundary component characteristics and difficult threshold tuning in existing DC grid backup protection. Firstly，by considering the structure of the T-connection zone busbar and the connected transmission lines on both sides，the corresponding fault characteristics are analyzed. Secondly，fault features are constructed by extracting three key parameters at the measurement point during faults： the polarity of line-mode power mutation quantities，the high-frequency energy of line-mode power，and the amplitude difference of voltage mutations. Furthermore，the fault features and fault types are taken as the input and output variables of BiTCN，respectively，and a line protection criterion based on BiTCN is established. Finally，a simulation model of the Ultra high voltage three-terminal hybrid DC transmission system is developed using for verification. The results demonstrate that the proposed protection scheme can accurately detect faults across the entire line，withstand high fault resistance，and achieve both reliability and quick-action.