Space Charge Density Measurement Around DC Transmission Lines Based on Ion Counter

When HVDC transmission line runs across areas with large number of aerosol particles suspended in dry air, changes of space charge density distribution may lead to high ground electric field strength. To study this phenomenon, space charge measurement is a direct and effective means. Ion counting principle and equivalent circuit model of current detection were analyzed. Design guidelines were proposed. An instrument prototype measuring space charge density was designed. The instrument was calibrated with indirect calibration method. Using the instrument, space charge density around a test DC transmission line was measured. Results show that lateral charge density distribution and quantity changes with line voltage are similar to resultant electric field and ion current density. The instrument can availably measure space charge density around HVDC transmission line.