*Article* **Statistical Study on Space Charge e** ff**ects and Stage Characteristics of Needle-Plate Corona Discharge under DC Voltage**

#### **Disheng Wang, Lin Du \* and Chenguo Yao**

State Key Laboratory of Power Transmission Equipment and System Security and New Technology, Chongqing University, Chongqing 400030, China

**\*** Correspondence: dulin@cqu.edu.cn

Received: 30 June 2019; Accepted: 12 July 2019; Published: 17 July 2019

**Abstract:** The air's partial discharges (PD) under DC voltage are obviously a ffected by space charges. Discharge pulse parameters have statistical regularity, which can be applied to analyze the space charge e ffects and discharge characteristics during the discharge process. Paper studies air corona discharge under DC voltage with needle-plate model. Statistical rules of repetition rate (*n*), amplitude (*V*) and interval time ( Δ*t*) are extracted, and corresponding space charge e ffects and electric field distributions in PD process are analyzed. The discharge stages of corona discharge under DC voltage are divided. Furthermore, reflected space charge e ffects, electric field distributions and discharge characteristics of each stages are summarized to better explain the stage discharge mechanism. This research verifies that microcosmic process of PD under DC voltage can be described based on statistical method. It contributes to the microcosmic illustration of gas PD with space charges.

**Keywords:** partial discharge; needle-plate model; statistical rule; discharge stage; space charge
