5.4　Parameters of HVDC Transmission Line and Electrode

5.4.1　HVDC transmission line

5.4.1.1　General

The starting point，end point，voltage class，number of circuits，rated current，and line length of the HVDC transmission line shall be given.

5.4.1.2　Transmission line data

5.4.1.2.1　Data of conductor and ground wire

1　The data of HVDC transmission pole conductors mainly includes:

（1）Type.

（2）Standards.

（3）Structure，including the respective numbers and diameters（mm）of aluminum and steel portion in pole conductors.

（4）Cross section（mm2），including respective cross sections of aluminum and steel portion and total cross section.

（5）Outer diameter（mm）.

（6）Unit weight（kg/km）.

（7）Rated tensile strength（N）.

（8）DC resistance under 20°C（Ω/km）.

The number of bundles of each pole conductor，spacing between bundles，type of two ground wires used on HVDC transmission line and their specific parameters shall also be indicated.

2　The data of ground wire mainly includes:

（1）Type.

（2）Standards complied with.

（3）Structure，number/diameter（mm）.

（4）Cross section（mm2）.

（5）Outer diameter（mm）.

（6）Unit weight（kg/km）.

（7）Rated tensile strength（N）.

3　Characteristics of optical fiber composite overhead ground wire（OPGW）mainly include:

（1）Optical fiber cable type.

（2）Standards complied with.

（3）Outer diameter（mm）.

（4）Number of optical fiber conductors in a cable.

（5）Optical fiber type.

（6）Maximum attenuation coefficient at 1550nm（dB/km）.

（7）Maximum attenuation coefficient at 1300nm（dB/km）.

（8）Maximum dispersion［ps/（nm·km）］.

（9）Diameter of mode field at 1500nm（μm）.

（10）Critical wavelength（nm）.

5.4.1.2.2　Tower dimension

In terrains such as plains，hills and mountains，the tower dimension and tower grounding resistance shall be given，as well as the protection angle of ground wire，average conductor height under given average temperature，and average ground wire height.

5.4.1.2.3　Ground conductivity along HVDC transmission line

The ground conductivity along HVDC transmission line shall be given.

5.4.2　Electrode

5.4.2.1　Location of electrode

The distance and orientation of recommended electrode site to converter station shall be given.

5.4.2.2　Soil parameters

The soil resistance at electrode site shall be given.

5.4.2.3　Parameters of electrode

Parameters of the electrode，such as resistance，shall be provided.

5.4.3　Electrode Line

5.4.3.1　Conductor data

Electrode conductor structure，type，spacing between conductor bundles，way of installation on tower，type of ground wire used shall be given.

The data of electrode line is the same as in 5.4.1.2.1.

5.4.3.2　Data of tower for electrode line

See 5.4.1.2.2.

5.4.3.3　Insulation coordination of electrode line

The insulation coordination measures of electrode line shall be given.