The influence of greenhouse support structures on ion flow field under overhead high voltage direct current lines

ABSTRACT When an overhead high voltage direct current (HVDC) line is near a greenhouse, surface charges on the dielectric film distort the electric field nearby. Extensive experimental researches have been conducted regarding charge characteristics, and various algorithms have been proposed to calculate the ion flow field considering the charged film. However, existing studies do not consider the greenhouse support structures. In this paper, based on the ion flow field simulation with charged film, a more complete greenhouse model considering support structures is built. The support structures are treated as grounded conductors. Experimental results agree well with the calculations. Then, the influences of the frames and the wall (two typical types of support structures) are analyzed separately. The analysis considers the frame radius, position, and number, as well as the wall position and width. The total electric field is divided into three parts by charge sources, the effects of which are analyzed separately. The co-effect of the two kinds of support structures is also analyzed. The calculations show that the support structures, which are conductive and grounded, can effectively reduce the ground-level electric field. This research can predict the absolute value and help us understand the characteristics of the actual electric field near a greenhouse built under overhead HVDC lines.