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Method for protecting inverter in distributed generating system

A distributed power generation and inverter technology, applied in emergency protection circuit devices, electrical components, etc., can solve reliability problems, complexity of power switch control, imperfect inverter protection, etc., and achieve sensitive and reliable actions , clear principle, fast and accurate calculation

Inactive Publication Date: 2011-08-24
TIANJIN UNIV
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  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

At the same time, due to the fragility of the power switch tube in the inverter and the complexity of control, the inverter has become the weakest link in the system that is most prone to failure, and its reliability problems have always existed [3，4]
[0005] From the above analysis, it can be seen that the protection of the inverter is not perfect at present. It is necessary to invent a protection scheme with new principles through the analysis of its fault characteristics. It can quickly and reliably disconnect the connection switch of the inverter to ensure the safe operation of the conventional power system connected to the grid with distributed power

Method used

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  • Method for protecting inverter in distributed generating system
  • Method for protecting inverter in distributed generating system

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Embodiment Construction

[0026] In the following, the protection principle on which the present invention is based is analyzed in conjunction with the accompanying drawings, and the technical solution of the present invention is further described.

[0027] For attached figure 1 Provided inverter, the present invention adopts the method of switch function, promptly utilizes formula (1) to analyze various faults that it may occur

[0028] i dc = i a S a + i b S b + i c S c (1)

[0029] Among them, i dc is the current on the DC side; i a i b i c is the fault current on the AC side of the inverter; S a , S b , S c is the switch function. The analysis results show that: when the internal power switching elements of the inverter are short-circuited, the current on the DC side increases significantly; when the internal power switching elements of the inverter are open-circuited, the current components appearing on the DC side are listed in Table 1; When an asymmetrical short circuit occur...

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Abstract

The invention belongs to the field of a distributed generating system of renewable energy sources, and relates to a method for protecting an inverter in a distributed generating system. The method is characterized by comprising overcurrent protection, overvoltage protection, undervoltage protection and overheating protection for a direct-current (DC) side, short-circuit protection and anti-isolated island protection for an alternating-current (AC) side, and fundamental overcurrent protection and secondary harmonic overcurrent protection for the DC side. The protection mode is as follows: DC current data at the DC side are collected, and a fundamental component and a secondary harmonic component are acquired after the data are processed by Fourier transform; overcurrent protection criterions of fundamental waves and secondary harmonic waves are set, and an overcurrent protector of the fundamental waves or the secondary harmonic waves acts when respective criterion is met. In the scheme provided by the invention, the principles are clear, and fault characteristics of the inverter are utilized sufficiently, thus being capable of quickly, flexibly and reliably reflecting short-circuit and disconnection faults of power tubes and a short-circuit fault of the AC side inside the inverter.

Description

technical field [0001] The invention relates to the field of distributed power generation systems of renewable energy, in particular to an inverter relay protection scheme in distributed power generation systems such as solar energy and wind energy. Background technique [0002] With the gradual depletion of traditional fossil energy, green distributed power generation systems such as solar energy, wind energy and tidal energy are increasingly being applied. Therefore, it is of great practical significance to study the distributed grid-connected power generation system composed of new energy and conventional power systems. [1，2] . [0003] In a distributed power generation system, the voltage source inverter is the core and most important device of the whole system. At the same time, due to the fragility of the power switch tube in the inverter and the complexity of control, the inverter has become the weakest link in the system that is most prone to failure, and its relia...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): H02H7/122
Inventor 张艳霞赵杰
Owner TIANJIN UNIV
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