受输电走廊的制约，同塔双回直流线路已成为直流输电工程建设的发展趋势之一，然而由于同塔双回直流线路极线间的电磁耦合关系导致了其故障暂态特性极为复杂。行波保护作为直流线路主保护，故障行波特性的研究对其动作性能的分析至关重要。为此，基于无畸变线路模型研究了同塔双回直流线路故障电压电流的相模变换方法和模量求解方法；系统地分析了极线故障行波的特性及其与单回直流线路的差异性，以及实际同塔双回直流线路不对称换位和参数频变等影响因素；基于PSCAD/EMTDC电磁暂态仿真软件进行了分析验证。研究成果有助于对目前基于单极线电气量的直流线路行波保护动作性能的分析以及其在同塔双回直流线路上的适应性研究。%Owing to the shortage of transmission space, double-circuit HVDC on the same tower has been widely applied in the power construction. However, the electromagnetic coupling of different pole in two circuits makes the transient electrical characteristics complex when a fault occurs. The protection based on travelling-wave plays a main role in direct circuit protection, which makes great significance in the study of travelling-wave characteristics in double-circuit HVDC, so as to win the master of operating performance of line protection. As a result, based on the Bergeron line model, the method of phase-mode transformation and modulus calculation for line voltage and current when a fault happens in double-circuit HVDC is proposed firstly. Then the travelling wave characteristics in double-circuit HVDC and the difference from travelling-wave HVDC in single-circuit are analyzed systematically. After that, the influence factors of asymmetric transposition of transmission lines and frequency dependent parameter are taken into consideration. Finally, the theory is analyzed and verified in the platform of PSCAD/EMTDC. The results of this paper help to analyze the performance and the adaptability in double-circuit of the travelling wave protection based on single-pole electrical information.
展开▼
