An economical hybrid DC circuit breaker with pre-current-limiting capability

Abstract

Multi-terminal flexible high-voltage-direct-current (HVDC) transmission and DC grid technology are developing rapidly, and the hybrid DC circuit breaker (DCCB) is usually used to protect the DC system, which can quickly remove the fault current and make sure the safe and stable work of system. However, the existing hybrid DCCBs have restrictions regarding one or more of the following characteristics: economy, fast adaptive reclosing, low on-state losses, and no additional pre-charge power source. This paper presents an economical hybrid DCCB with pre-current-limiting capability (EP-HCB), in which the main branch only is made up of mechanical switch (MS) and the fault handling branch consists of fault current transfer circuit, current limiting circuit and breaking circuit. And the proposed EP-HCB itself has inherent pre-charging and adaptive reclosing capabilities and low on-state losses, which efficiently limit the magnitude and rise rate of fault current and thus weaken the opening requirements on the DCCB. Detailed topology structure of the EP-HCB is presented, and the work principle of the fault current commutation and limiting are analyzed. Then, a design method for parameters of the proposed EP-HCB is provided. Finally, based on the 4-terminal simulation system in PSCAD/EMTDC, the feasibility and economy of the EP-HCB are proved by comparison with ABB hybrid DCCB.