Protection method for closed-loop power distribution network containing distributed power supply

Abstract

The invention discloses a protection method for a closed-loop power distribution network containing a distributed power supply. The method comprises the following steps: accessing a DG to a power supply branch of the power distribution network, and arranging a DG circuit breaker on the access bus of the DG, wherein the DG circuit breaker is used for short-circuit current detection and direction judgment; connecting the tail end of the power supply branch with the DG and the tail end of another power supply branch through an interconnection switch to form the closed-loop power distribution network; adopting a longitudinal overcurrent protection technology for the closed-loop power distribution network, and carrying out opposite protection action by an upstream line if the upstream of the DGaccess bus is faulted in order to achieve isolation and maintain the DG in a power supply state; and carrying out protection action by a downstream line if the downstream of the DC access bus is faulted in order to achieve isolation and keep the DG in the power supply state. The method can isolate any fault of the closed-loop power distribution network in a very short time, at most one bus loadis lost, and the DG is not cut off, so the power supply reliability and the DG utilization rate of the closed-loop power distribution network can be effectively improved.

Description

technical field [0001] The invention relates to a protection method for a closed-loop distribution network including a distributed power supply, and belongs to the technical field of safe operation of electric power systems. Background technique [0002] At present, with the continuous maturity and improvement of my country's policy support and related equipment manufacturing technology, a large number of distributed generation (Distributed Generation, DG) such as photovoltaic and wind power have been connected to the distribution network. At the same time, due to the increasing penetration rate of DG and the user's requirements for power supply reliability, the closed-loop operation of the distribution network has its urgency. For the distribution network with DG closed loop, a reasonable protection scheme can be formulated to realize rapid and small-scale effective isolation of faults in the loop, and promote safe and reliable system operation and new energy consumption. ...

AI Technical Summary

Problems solved by technology

[0003] For the protection scheme of the distribution network including DG loop closure, the de-loop definite time overcurrent protection strategy makes full use of the original open loop definite time overcurrent protection without additional configurations such as circuit breakers and directional elements, but it is difficult to improve the power supply of closed loop operation Reliability and DG utilization; directional definite time overcurrent protection is equipped with circuit breakers at both ends of the line, and directional elements are installed. To meet the needs, the rapid isolation of faults close to the system cannot be guaranteed; the fault is identified and located through the sampling data of the synchrophasor measurement device and network parameters, so as to achieve fault isolation. The domain protection control scheme uses scalable differential protection and a load shedding method based on load sensitivity, which also has the problems of huge investment and high communication requirements

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