混合多端直流输电线路主动式继电保护与重合/重启方法研究

Hybrid multi-terminal DC transmission technology is the future direction development, and the core is the converter. The converter has the characteristics of vulnerability and high controllability. The Vulnerability is the root cause of a series of HVDC safety and stability issues, and the high controllability is the key factor to solve these problems. Based on the high controllability of the converter, this project aims to solve the low reliability problem of conventional DC protection and propose an adaptive reclose / restart strategy suitable for hybrid DC transmission lines. Firstly, the interaction mechanism between control characteristics and fault characteristics of hybrid HVDC transmission is analyzed to reveal the corresponding rules of additional control strategy and fault characteristic increment. At the same time, an electromagnetic transient real-time simulation model of hybrid HVDC transmission system is built. Then the adaptability of existing DC line protection in hybrid multi-terminal DC transmission system is analyzed. On this basis, using the high controllability of the converter, an active protection principle of the hybrid DC transmission line is proposed, and the combined active and passive hybrid DC grid protection scheme is formed to make up for the shortcomings of the existing DC line protection. Finally, by injecting the disturbance signal or low current into the robust pole or faulty pole through the converter, two active reclose / restart methods are proposed. And according to the characteristics of the two methods, an adaptive coincidence / restart strategy which can reliably identify permanent faults and quickly recover from transient faults is formed. The research can provide a theoretical basis to ensure the safe and stable operation of hybrid DC transmission lines.

混合多端直流输电技术是今后的发展方向，其核心是换流器。换流器具有脆弱性和高可控性，其中脆弱性是导致直流输电安全稳定问题的根源，高可控性是解决问题的关键因素。本项目从换流器的高可控性出发，旨在利用其解决常规直流保护的低可靠性问题，同时提出适用于混合直流输电线路的自适应重合/重启策略。首先分析混合直流输电控制特性与故障特征间的作用机理，揭示附加控制策略与故障特征增量的对应规律，并搭建混合多端直流输电系统的电磁暂态实时仿真模型；然后分析现有直流线路保护在混合多端直流输电系统中的适应性；基于此，利用高可控性，提出混合直流输电线路的主动式保护原理，弥补现有直流线路保护存在的不足；最后利用换流器在故障极注入扰动信号或低电流，提出两种主动式重合/重启方法，并形成能够可靠判别永久性故障和瞬时性故障快速重合的自适应重合/重启策略。本项目研究可为保障混合直流输电线路的安全稳定运行提供理论依据。

混合多端直流输电技术是今后的发展方向，其核心是换流器。换流器具有脆弱性和高可控性，其中脆弱性是导致直流输电安全稳定问题的根源，高可控性是解决问题的关键因素。本项目从换流器的高可控性出发，旨在利用其解决常规直流保护的低可靠性问题，同时提出适用于混合直流输电线路的自适应重合/重启策略。首先分析混合直流输电控制特性与故障特征间的作用机理，揭示附加控制策略与故障特征增量的对应规律，并搭建混合多端直流输电系统的电磁暂态实时仿真模型；然后分析现有直流线路保护在混合多端直流输电系统中的适应性；基于此，利用高可控性，提出混合直流输电线路的主动式保护原理，弥补现有直流线路保护存在的不足；最后利用换流器在故障极注入扰动信号或低电流，提出两种主动式重合/重启方法，并形成能够可靠判别永久性故障和瞬时性故障快速重合的自适应重合/重启策略。本项目研究可为保障混合直流输电线路的安全稳定运行提供理论依据。