Characterizing the Surface Charge Distribution and its Impact on the DC Surface Flashover Voltage of Insulators

Medium-voltage direct current (MVDC) distribution systems are proposed for future all-electric ships. For widespread adoption, it is critical to develop creepage distance standards that are applicable for MVDC shipboard power systems. Surface flashover voltage is an important factor affecting the required creepage distance. While the importance of this topic has been recognized for terrestrial HVDC transmission applications, its investigation for MVDC shipboard power systems is in its infancy. This paper studies the characteristics of surface charge distribution along insulators under MVDC stress as well as its impact on the flashover voltage. It is shown that surface charge distribution varies under different voltages. The surface charge accumulated in the middle of the spacer will increase the surface flashover voltage, and with similar profile, the surface flashover voltage will decrease with higher average charge density. Besides average surface charge density, more features of surface charge profile have been found influencing surface flashover voltage.