Reducing Peak Current and Energy Dissipation in Hybrid HVDC CBs Using Disconnector Voltage Control

Peak fault current and energy dissipation in high-voltage direct current (HVdc) circuit breakers (CBs) are very important parameters that impact dc grid protection development. This paper analyzes a hybrid DCCB (HCB) control that reduces peak current and energy dissipation by regulating the voltage across contacts of the ultrafast disconnector (UFD). This is achieved by manipulating the number of inserted surge arresters while contacts of the UFD are moving apart. The controller is seamlessly integrated with the current controller of HCBs. An analytical model for current and energy calculation is presented, verified, and employed for parametric studies. A PSCAD simulation with 320-kV, 16-kA test circuit confirms that the proposed voltage control reduces the peak current and energy dissipation by around 20%–30%. A 900-V, 500-A HCB laboratory hardware is described and the experimental results are shown to corroborate simulation conclusions.