The Calculation Method of the Floating Conductor Potential in the Ion Flow Field

Abstract

For bipolar DC transmission projects, when one pole conductor is charged and running normally, and the other pole conductor is in a standby state (including cold standby and hot standby), if the standby pole conductor is not grounded, a high charging potential will appear on the surface. On the one hand, it will affect the insulation coordination and protection setting of the DC system. On the other hand, it will also affect the ion current and synthetic electric field on the ground. This article studies the calculation method of the potential of suspended conductors in the presence of floating conductors in the ion flow field, establishes a calculation model based on the minimum absolute value of the space charge density on the surface of the conductor, and calculates and analyzes the distribution of ionizing current and synthetic electric field below the ground of high-voltage DC lines in the presence of suspended conductors. The distribution laws of ground field strength and ion current in single-circuit bipolar DC transmission lines are studied when one pole is suspended, the other is operated, and when one circuit is operated. One circuit is shut down in double-circuit DC transmission lines on the same tower. For practical engineering, on the one hand, it is possible to predict the potential of suspended conductors in the ion flow field and propose adjustment plans for protection settings, insulation coordination, etc., in advance. On the other hand, when considering abnormal operating conditions, the impact of ion flow fields on the ground electromagnetic environment can be reduced by changing the geometric architecture and line selection.