Measurement of corona-generated space charge density under DC test wire

Corona-generated space charge density is an important quantity that helps describe the electrical environment in the vicinity of High Voltage Direct Current (HVDC) transmission lines. This paper develops a device based on the ion counter method to measure space charge density under a DC test wire, which is used to simulate a HVDC transmission line. An experiment is carried out to analyze the various factors affecting the measurement. Another experiment, comparing the device with the indirect rotating field-mill method which is often used to measure space charge density at the ground level, is conducted to verify the feasibility and validity of the device and to calibrate its accuracy. Based on the device, the space charge distributions under the test wire are measured and analyzed.