Speaker
Description
Recently, flexible DC transmission has been developed rapidly in the Off-site grid interconnection. Inhibiting the sudden increase of DC current caused by short-circuit faults is necessary for the protection of power grid. Generally, the short-circuit faults may be caused by physical conduction or arcing and sparking. To address permanently damage the power grid, a resistance type high-temperature superconducting (HTS) short-circuit fault current limiter (SFCL), which has the advantages of large capacity, low conducting loss and simple structure, has been proposed. However, because this conventional SFCL s based on 1st generation BiSCCO HTS material lacks of thermal stability and mechanical strength, it may easily burn out owing to the thermal runaway during a quench. Moreover, the conventional resistance SFCL is also reported that needs several seconds recover from a quench.
Hence, we proposed a new resistance type REBCO SFCL based on using no-insulation (NI) winding technology. The NI coil is reported that have many excellent features: 1) hardly burn-out during an overcurrent; 2) self-protectable, never need to be paralleled a protective resistance; 3) voltage division characteristic during an overcurrent. Based on these advantages, the SFCL adopted NI winding technique is expected to inhibit the temperature increase during an overcurrent and substantially enhance the reliability itself. Hence, the NI-SFCLs becomes reusable and its recovery time can be shorter.
In this study, we designed a NI-SFCL applying in 350 kV flexible DC transmission based on numerical simulation. The feasibility of designed NI-SFCL is discussed based on the investigation of the current and voltage behaviors during short-circuit faults, boost faults and spark discharge faults. To certify the high reliability and short recovery time of NI-SFCL, we estimated the Joule-heat and the temperature during a current limiting process. Then, we also evaluate the influence of turn-to-turn contact resistance and thickness of copper stabilizer layer on voltage division and temperature increase of NI-SFCL during a current limiting process.
Key Word: Flexible DC transmission, no-insulation coil, quench, SFCL, REBCO, turn-to-turn contact resistance
