Unbalance protection is one of the most important protection functions in the high voltage capacitor protection scheme. It can reflect the faulty capacitor element directly. Based on the real projects in Southern Grid

such as Pingguo TCSC

Hechi FSC

Baise FSC

Tianguang HVDC and Guiguang HVDC project

this paper analyzes the related problems of capacitor unbalance protection

such as current transformer connection

type selection and the match problem. The unbalance detection principles are summed up and compared. Problems that should be considered in setting calculation are also described.