海拔对直流输电线路可听噪声的影响机理及修正方法研究

Audible noise (AN) generated from corona discharge of transmission line keeps a close relationship with the environment protection and project cost. Especially at high altitude area, AN has become the key technical factor which decides conductor type and transmission line structure. Currently, the study on AN for HVDC transmission line at high altitude was not yet sufficient, so in the HVDC transmission lines design at high altitude, the AN altitude correction method of AC transmission line was adopted usually, but it lacked of experimental support. In this research project, with the help of four DC reduced-scale test lines in the altitude range of 0-4300m belonged to China Electric Power Research Institute (CEPRI), a long-term test of AN will be carried out under the conditions of different altitudes, different weather and different conductor corona. Using the test data above, the influence of altitude on sound source power and different frequency components will be studied. In addition, combined with corona current test, the relationship between AN and corona current for HVDC transmission lines high altitude area will be also studied statistically. From the corona discharge point of view, the internal mechanism between AN and altitude will tried to be given the answer. Finally, using the two UHVDC full-scale DC test lines at high and low altitude areas, a new AN altitude correction method for HVDC transmission lines with broad applicability will be put forward..Through the work finished in this research project, it can not only improve the theoretical understanding of DC corona characteristics and its effect at high altitude, but also provide a new AN altitude correction method of HVDC transmission lines, and thereby to provide guidelines for designing the HVDC transmission line at high altitude areas in our country.

输电线路可听噪声与环境保护、工程投资密切相关，尤其在高海拔地区，可听噪声已成为直流线路导线选型和线路结构设计的决定因素。目前国内外关于海拔对直流线路可听噪声影响的研究尚不充分，在工程设计中主要借鉴交流线路的海拔修正结论，但缺乏试验支撑。本项目拟利用中国电科院在海拔0-4300m范围内的四个直流模拟试验线段，开展不同海拔、不同气象条件、不同导线起晕状况下的可听噪声长期测试，研究海拔对噪声声源功率及不同频率分量的影响规律；结合电晕电流测试，研究高海拔环境下直流线路可听噪声与电晕电流在统计学意义上的关联关系，从电晕放电角度揭示直流可听噪声随海拔变化规律的内在机理；最后，结合真型试验，提出具有广泛适用性的直流输电线路可听噪声海拔修正方法。.通过本项目研究，不仅可以完善我国对于高海拔直流线路电晕特性及其效应的理论认知，还可提出新的直流可听噪声海拔修正方法，从而为我国高海拔直流线路设计提供技术指导。

高海拔直流输电线路可听噪声预测是否准确，直接关系到工程投资与环境保护，但国内外对此缺乏系统研究。本项目针对我国直流输电发展面临的关键技术问题，通过在不同海拔开展可听噪声和电晕电流试验，研究了海拔对高压直流输电线路可听噪声的影响机理及修正方法。.基于声波传播理论，提出了一种在高背景干扰环境中滤除背景噪声干扰的方法，可有效获得测试环境中稳态背景噪声的大小。通过不同海拔试验，揭示了直流输电线路可听噪声增加量随海拔增加呈非线性变化的重要规律，在海拔50m～4300m范围，随着海拔增加，可听噪声呈现“缓慢增加——快速增加——缓慢增加”的特点；随着导线表面场强由小到大增加，可听噪声的海拔修正量呈现先增加后减小的倒“U”形特点。给出了直流线路可听噪声频率分量随海拔变化的关系，直流输电线路A声级噪声的能量主要集中在2000Hz～10000 Hz的频带范围内， 2~2.5kHz和5~8kHz范围内的单频噪声声压级的海拔修正规律与总体A声级噪声符合性较好。给出了直流输电线路电晕电流的降噪方法，获得了电晕电流频谱特性规律及主要能量所在的频率范围，提出了利用电晕电流平均值获得可听噪声的计算公式。提出了海拔0m～4300m的直流输电线路可听噪声海拔修正公式，解决了高海拔直流输电线路可听噪声预测、导线选型等方面遇到的技术瓶颈问题。采用本文提出的公式预测的不同海拔直流输电线路可听噪声远小于按美国EPRI推荐公式预测的结果，应用在高海拔直流输电线路设计中，可在满足环境保护要求的前提下，大量节省线路投资。