The Initial Characteristics for DC Corona Discharge Considering the Effect of Space Charge Density

The corona initiation characteristics are important for the design and operation of high-voltage equipment and the protection of ecological environment. In the case of ultrahigh-voltage transmission lines, the determination of corona initiation characteristics can be used to reduce transmission losses and analyze the electromagnetic environment to ensure economical and environmentally friendly power transmission. In this work, a streamer model is developed to analyze the effects of space charge on the onset voltage and electric field of dc corona discharge. Meanwhile, space charge density measured by sound pulse method is adopted as a kind of new parameters to determine onset voltage, and the effectiveness can be determined by the test results of corona current and photon number and the calculation results of streamer model. The results show that onset voltage considering space charge is obviously smaller than that when the space charge field is ignored, which indicates that the space charge has a certain promotion effect on the negative corona discharge. Compared with the onset voltage confirmed by corona current and photon number, the onset voltage determined by space charge is less dispersed, and it has the smallest error of 4.69% from the theoretical value obtained from the model calculation, which indicates the validity of space charge characterization of corona initiation characteristics. This work not only analyzes the effect of space charge on corona discharge process but also provides a feasible method for the analysis of corona discharge in air.