Island detection method based on negative sequence voltage divider

A technology of island detection and voltage divider, which can be used in instruments, measurement devices, measurement devices, etc., can solve the problems of high cost and complex island detection structure.

CN102565598AInactive Publication Date: 2012-07-11NORTH CHINA ELECTRIC POWER UNIV (BAODING)
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Patent Information

Authority / Receiving Office
CN · China
Patent Type
Applications(China)
Current Assignee / Owner
Publication Date
2012-07-11
Estimated Expiration
Not applicable · inactive patent

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Abstract

The invention discloses an island detection method based on a negative sequence voltage divider in a distributed power generation system detection technology field. The method is characterized by: firstly extracting an effective value of the negative sequence voltage at a position of a micro-grid common connection point; then calculating a ratio of the effective value to the effective value of a negative sequence voltage source which is added on the common connection point; when the ratio is less than a set threshold, determining that the island is not generated; when the ratio is greater than or equal to the set threshold, determining that the island is generated. By using the method of the invention, under various kinds of fault conditions and other scurviness situations, the island can be effectively detected. The detection is only related to a network topology structure and a pseudo island can not influence the detection. An on-site application requirement can be satisfied and the method possesses actual engineering significance.
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Description

technical field

[0001] The invention belongs to the technical field of distributed power generation system detection, and in particular relates to an island detection method based on a negative sequence voltage divider. Background technique

[0002] In recent years, with the development of distributed generation technology, the microgrid system composed of distributed generation (distributed generation, DG) and local loads has become a useful supplement to the large power grid. The microgrid can not only be connected to the large power grid to supply power to the grid, but also can operate in an isolated island to independently supply power to local loads. Since the control methods of the microgrid are different between grid-connected operation and islanded operation, when the microgrid changes from the grid-connected state to the island state, it is required that the internal DG can quickly and accurately obtain signals to realize the smooth switching of the control mode. ...

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Embodiment Construction

[0038] The preferred embodiments will be described in detail below in conjunction with the accompanying drawings. It should be emphasized that the following description is only exemplary and not intended to limit the scope of the invention and its application.

[0039] The purpose of the present invention is to overcome the shortcomings of the prior art and provide an islanding detection method based on a negative-sequence voltage divider. Islanding refers to the situation in which a grid-connected microgrid system is disconnected from the large grid and continues to supply power to local loads in the event of a large grid failure.

[0040] The interior of the microgrid can be simplified as a model of DG and local loads, and the microgrid is connected to the distribution network through a common connection point. The distribution network has a large capacity and a small equivalent impedance, while the microgrid has a small capacity and a large equivalent impedance. When the ...