考虑频变参数和直流控制的直流输电系统线路故障解析

Analysis of Line Faults on HVDC Transmission System Considering Frequency-dependent Parameters and HVDC control

提出了考虑频变参数和直流控制的直流输电系统线路故障时域解析方法,为直流线路故障分析与故障检测提供了解析基础和实用工具。首先,建立了直流输电系统线路故障的复频域模型,推导了故障电气量的复频域表达式。继而,根据故障行波沿直流线路的传播规律,提出了频变参数的惯性等值模型;根据直流线路故障后直流控制系统的动作规律,提出了直流控制的比例—积分等值模型。进一步,基于频变参数和直流控制等值模型,对复频域故障电气量进行拉氏反变换得到时域表达式,并对解析结果与EMTDC仿真结果进行比较,相关结果验证了所提出的解析方法的有效性。最后,探讨了故障解析可能的工程应用场景,以直流线路行波保护为例进行了具体分析,分析结果表明故障解析具有良好的工程应用价值。

A time-domain analytical method for line faults on high-voltage direct current(HVDC)transmission system considering frequency-dependent parameters and HVDC control is proposed,providing the analytical basis and utility tool for fault analysis and detection of HVDC lines.Firstly,a complex frequency domain model for line fault of HVDC transmission system is developed and the complex frequency domain expression of fault electrical quantities is derived.Secondly,the inertia equivalent model for frequency-dependent parameters is proposed based on the propagation rule of the faulty travelling wave.The proportional-integral equivalent model for HVDC control is proposed based on the action rule of the HVDC control system after HVDC line fault.Then,inverse Laplace transformation is adopted to obtain the time-domain expressions considering the frequency-dependent parameter and HVDC control equivalent model.A comparison of the analytical results with the simulated ones in EMTDC shows the validity of the proposed analytical method.Finally,potential engineering application scenarios of the analytical method is discussed,e.g.,its successful use in HVDC travelling wave protection.