Abstract
A DC circuit breaker is piece of core equipment for DC grid construction and can achieve fast isolation of DC faults in the grid. In this paper, based on the fault characteristics and protection requirements of an AC/DC hybrid distribution network, the technical parameters and topology structure of an inductance and capacitance (LC) resonant commutation-type mechanical DC breaker are proposed. Furthermore, an engineering prototype of the mechanical DC circuit breaker is developed, then a small current breaking test and a large current breaking test are carried out. The test results show that a 10 kA fault current can be interrupted within 10 ms by the engineering prototype. Finally, the engineering prototype of the mechanical DC circuit breaker is installed in the AC/DC hybrid distribution network project, and a current breaking test is carried out. The test results show that the mechanical DC circuit breaker has good running conditions, and the function and performance meet the engineering design and operation requirements.
Highlights
A flexible DC grid has the advantages of no need for reactive power compensation equipment, no commutation failure, and a power supply for passive systems, it has become one of the hot research directions in recent years [1,2,3]
A typical topological structure of a mechanical DC circuit breaker based on LC resonant commutation is shown in Figure 4, wherein M refers to the quick mechanical switch, S1-S5 refers to
A typical and topological structure of a mechanical breaker based on LCfault resonant absorption. is shown in Figure 4, wherein M refers to the quick mechanical switch, S1–S5 refers to the commutation thyristor, K refers to the bypass switch, C refers to the resonant capacitor, L refers to resonant inductance, Rp refers to static equalizing resistance, Rs refers to dynamic equalizing resistance, Cs refers to dynamic equalizing resistance, MOA1–MOA2 refers to the metal oxide arrester for restricting over-voltage, and MOA refers to the metal oxide arrester for restricting over-voltage and fault energy absorption
Summary
A flexible DC grid has the advantages of no need for reactive power compensation equipment, no commutation failure, and a power supply for passive systems, it has become one of the hot research directions in recent years [1,2,3]. There are two main methods for mechanical DC circuit breakers to achieve DC fault current breaking by manufacturing manual zero-crossing points [10,11]. The first method is to use the arc voltage generated by the mechanical switch during the breaking process to achieve current zero crossing. DC circuit breaker is proposed, the engineering prototype is commutation type mechanical DC circuit breaker is proposed, the engineering prototype is developed, developed, and a current breaking test is carried out. DCis circuit breaker is installed in distribution the AC/DCnetwork hybrid project distribution network project to circuit breaker installed in the AC/DC hybrid to achieve fast isolation of achieve fast isolation of faults, ensuring safe and reliable operation of the system. DC faults, ensuring safe and reliable operation of the system
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