Current differential protection method for smart distribution network

A smart distribution network and current differential technology, which is applied in the direction of automatically disconnected emergency protection devices, emergency protection circuit devices, electrical components, etc., can solve the problems that current differential protection cannot be applied to distribution networks, and achieve good adaptability , flexible configuration

CN101938117AActive Publication Date: 2011-01-05SHANDONG UNIV +1
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Patent Information

Authority / Receiving Office
CN · China
Patent Type
Applications(China)
Current Assignee / Owner
Publication Date
2011-01-05

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Abstract

The invention relates to a current differential protection method for a smart distribution network, which comprises: mounting current transformers and smart distribution terminals at the positions of all switches in the smart distribution network, wherein each smart terminal serves as an agent, the agents are connected with one another through an optical fiber Ethernet, and the positive directions of all currents is the direction from a system power supply to the end of a circuit; automatically detecting the working state of a communication network through the agents, and determining if to perform current differential protection; when the communication network fails to work normally, applying the conventional three-stage current protection; when the communication network works normally, applying current differential protection and using the current differential protection as main protection; and allowing a local agent to compute a differential current and a braking current according to the local switching current detected by the local agent and downstream switching current transmitted by a downstream agent and determine if the protection is actuated. The overcurrent protection is local backup protection, and the protection of an upstream agent is local remote backup protection.
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Description

technical field

[0001] The invention relates to a current differential protection method suitable for an intelligent distribution network, and belongs to the technical fields of distribution network protection and intelligent distribution network. Background technique

[0002] Smart distribution grid (SDG) is an important part of smart grid (SG), and the difference between smart grid and traditional grid is more obvious in distribution network. The level of intelligence and automation of the existing distribution network is much lower than that of the transmission network, so the intelligence of the distribution network is an important part of building a smart grid. Since there are a large number of distributed power sources (DG) in the smart distribution network, after the DG is connected to the distribution network, the distribution network will no longer be a pure single power supply and radial power supply network. If the system fails, the magnitude of the short-circuit ...

Examples

Embodiment Construction

[0021] The present invention will be further described below in conjunction with the accompanying drawings and specific embodiments.

[0022] like figure 1 Shown is the program flow chart of the current differential protection method of the present invention. This protection method supports direct tripping by command, and it is possible to choose whether to enable or not through the direct tripping control word. The total starting element is a highly sensitive current mutation starting element. If the main starting element acts, it means that there may be a fault, and enter the fault handling program. Determine whether to enable the current differential protection by judging whether the network communication is normal. If the communication network is not working properly, the traditional three-stage current protection is enabled; if the communication network is working normally, the current differential protection is enabled. The program flow is briefly described as follows...