분산전원 적용을 위한 MVDC 배전망용 초전도 DC 차단기 설계

Abstract

Demand for power of the electricity is increasing worldwide as well as domestic demand. Currently most of the equipment that people use in normal is electric devices and the usage is increasing steadily because of the superiority and convenience of electricity. In recent, by the global warming, heating and cooling facilities are increasing every year. Moreover, new technologies such as smart-phone and EVs are also actively developing as new technologies. Due to the increase in power demand, it is urgent to establish countermeasures for power supply. There is a way to increase the unclear power generation or thermal power generation, which is responsible for the existing base development. However, it causes environmental pollution. In order to meet the demand, research and development of renewable energy sources such as solar or wind power is highly available. Most of the new renewable energy sources attempt to supply power to the system in a distributed power supply system form. Distribution power system refers to small power generation facilities utilizing new renewable energy sources to increase the simplicity and efficiency in the power systems across regions or networks. This is evaluated as a system with significant possibilities in terms of effectiveness and universality and environmental aspects. However, it is essential to secure the interruption technologies to ensure the actual application of the distributed power system. In the case of distributed power sources, the power is applied in various directions. And if the fault occurs, the fault current could generate with a overlap of various power, and it may cause a severe affect to the devices or the entire grid. Besides, most of the new renewable energies are generated in direct current. DC does not have a current zero. Therefore, in interruption operation in DC, it causes a large arc. If an unexpected arc occurs, the possibility of breaker failure will increase and it may damage circuit breaker and the contacts of it. For these reasons, DC interruption technology should be preceded by a priority to construct a stable distributed power system[1-3]. Electromagnetic transient for DC/PSCAD (EMTDC/PSCAD) program, power system analysis program, has conducted for simulation. This is made by Manitoba HVDC Research Center in Canada to analyze the DC transmission system based on CAD[4]. This paper suggests a superconducting DC circuit breaker that combines superconductor and mechanical dc circuit breaker. The superconductor is a limiting factor in the event of a fault. It limits the fault current by the quench characteristics of the superconductor. After the limitation operation, the limited fault current will flow into mechanical circuit breaker and it conducts a interruption operation. To demonstrate the superiority of the superconducting DC circuit breaker, it was applied to a single circuit to analyze the operational characteristics of the superconducting DC circuit breaker. To assure operability of the operation of the superconducting DC circuit breaker in MVDC distributed power system, grid-connected PV distributed system was applied to compare the operating characteristics.