高电缆化率对直流受端输电网谐波传递特性的影响

电缆线路占比增加将使直流受端输电网谐波传递特性发生改变。首先提出了电缆化率的概念,并推导出准确计及电缆化率的输电线路谐波模型,继而建立了计及电缆化率的交直流谐波经直流逆变站出线传递的谐波电压传递系数模型。最后,以上海宜华直流输电工程为例详细分析了在不同直流逆变站出线方式下电缆化率对直流受端输电网谐波相互传递特性的影响。研究结果表明:直流系统与受端输电网谐波相互传递特性受直流逆变站出线方式、线路参数、电缆化率及谐波频次制约;电缆化率增加会引起谐振频率左移,高频段谐波偏移程度更显著;所推导模型可根据线路实际参数、电缆化率定量分析谐波放大程度,作为未来受端输电网电缆线路规划及建设的重要依据。

Impact of High Cable Rate on Harmonic Transfer Characteristics of Transmission Power Grid at HVDC Receiving-End

Increasing the proportion of cable lines will change the harmonic transfer characteristics of the transmission power grid at HVDC receiving-end. In this paper,the concept of cable rate is proposed firstly,and the harmonic model of distribution parameters of transmission line that accurately considers the cable rate is derived. Then,the model of harmonic voltage transfer coefficient for AC and DC system harmonics transmitted through the outgoing line of HVDC inverter station is established,which considers the cable rate. Finally,taking Yihua HVDC project in Shanghai as an example,the influence of cable rate on harmonic interactive transfer characteristics of transmission power grid at HVDC receiving-end under different modes of outgoing line is analyzed in detail. The results show that the harmonic transfer characteristics between HVDC system and AC transmission power grid at receiving-end are constrained by modes of outgoing line at HVDC inverter station,parameters of outgoing line,cable rate and harmonic frequency;the increase of cable rate will cause the resonance frequency to shift to the left,and the offset in the high frequency is more serious. The derived model can quantitatively analyze the degree of harmonic amplification according to actual line parameters and cable rate,which is a significant basis for cable line planning and construction of receiving-end transmission grid in the future.