Abstract
DC distribution system has advantages of high power quality, large transmission capacity, high reliability, simple structure, economy and low energy consumption, and so forth. It has been a key part of smart grid nowadays. However, the development of DC distribution system is constrained by the lack of operational experience in DC system, the small interrupting capacity of DC circuit breaker (CB), and the lack of protection schemes for system itself. In this paper, protection for DC distribution system with distributed generator (DG) is fully investigated and verified. Firstly, the electromagnetic transient model of DC distribution system with DG is presented. Simulation based on the electromagnetic transient model is carried out. Both the step response and the steady-state performance verify the accuracy of the model. Then the fault characteristic mechanism is analyzed, and the protection principles and scheme are investigated in detail, including voltage mutation principle as protection starting component, differential current protection principle for DC bus, and two-section current protection for distribution lines. Finally, transient responses with protection scheme are analyzed during faults. The results present that the protection principles and scheme are feasible for DC distribution system with DG.
Highlights
Smart grid is an exciting development of power systems worldwide
The results present that the protection principles and scheme are feasible for direct current (DC) distribution system with distributed generators (DGs)
When fault F7 occurs, there is a slight fluctuation for DC voltage, while DC current of the inverter increases rapidly for a short time, which is provided in large part by the rectifier and in small part by DG
Summary
Smart grid is an exciting development of power systems worldwide. It is one of the scientific and technological innovations in the 21th century [1]. It can be well adapted to the connection of DGs and promote the development of DC appliances This is very essential for solving environmental pollution and energy depletion problems. Fault current characteristic of DC distribution system has been studied in detail [8], which lays a solid foundation for analyzing fault characteristic mechanism and exploring dynamic response characteristics In this respect of the fault location and isolation, a handshake method is proposed in [9]. A series of fault simulations are completed to verify the accuracy of protection principles and scheme
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