Application Research Of A Bridge Type Of Fault Current Limiter With Parallel Resonant Bypass

The rapid development of social economy has promoted great progress of powersystem and its related technologies. The expansion of the scale of power system andthe capacity increase of transmission and distribution system raise the level of theshort-circuit fault current, causing a lot of hidden dangers to the safe and stableoperation of the system. The traditional current limiting measures which are widelyadopted are very difficult to eradicate the increasingly serious excess of short-circuitfault current. Fault current limiter (Fault Current Limiter, FCL) receives extensiveattention at home and abroad as a significantly effective novel current limitingmeasure in the field of new type short-circuit current limiting technologies.This paper introduces several kind of typical resonance type FCLs and bridgetype FCLs, and proposes a kind of bridge type FCL with parallel resonant bypassbased on the two types FCLs. The proposed novel type FCL has the followingadvantages compared with typical resonance type FCLs and bridge type FCLs: It hasonly a controllable semiconductor switch, which significantly reduces the number ofsemiconductor power devices; Due to the diode rectifier bridge circuit isuncontrollable, only the controllable semiconductor switch needs to be controlledaccording to the running state of the system, thus greatly simplifying the controlcircuit; The bridge-type structure with single controllable switch can shorten the timeof the power supply applied on the DC reactor to the delay time of the fault detectioncircuit after short-circuit fault occurs, which effectively lowers the inductance valueand the rated current value of the DC reactor, thereby reducing the cost. The parallelresonant bypass of the proposed FCL can imitate load impedance during the fault andstably limit the fault current close to the level of pre-fault. It can avoid thelow-voltage side of the transformer experiencing a significant drop during the faultand provide ample time for the reliable action of the relay protection device (circuitbreaker), which effectively improves power quality and system reliability.The paper respectively presents the single-phase and three-phase circuit topology,working principle as well as control circuit of the proposed bridge type FCL. And theparameters of the FCL in single-phase and three-phase structure are designed andoptimized. The electromagnetic transient simulation software PSCAD is utilized to simulate current limiting effect of the novel type FCL in three-phase three-wiresystem and three-phase four-wire system under a variety of short-circuit modes. Thesimulation results prove the feasibility and effectiveness of the proposed FCL appliedin power system. Finally, the improvement and enhancement of the operatingperformance of power system utilizing the proposed FCL is analyzed from threeaspects.