Island detection method for droop control grid-connected inverter

An island detection and inverter technology, applied in the direction of instruments, measuring electronics, measuring devices, etc., can solve problems such as difficult monitoring, unsatisfactory island monitoring results, and easy misjudgment, so as to achieve easy monitoring and suppress interference , the effect of enhancing the accuracy

Inactive Publication Date: 2018-04-20
YANSHAN UNIV
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0003] For the traditional microgrid island monitoring scheme based on droop control, it is not only difficult to monitor but also prone to misjudgment
Make island monitoring results unsatisfactory

Method used

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  • Island detection method for droop control grid-connected inverter
  • Island detection method for droop control grid-connected inverter
  • Island detection method for droop control grid-connected inverter

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Embodiment Construction

[0027] The present invention will be further described below in conjunction with accompanying drawing:

[0028] The method of the present invention comprises the following steps:

[0029] Step 1, build the main circuit system of the three-phase grid-connected inverter; the three-phase main circuit structure adopts the three-phase half-bridge structure and the LC filter structure.

[0030] Step 2, calculate the output active power and reactive power of the three-phase grid-connected inverter;

[0031] Step 3, using the added perturbation k(f-f g ) / s The improved droop controller calculates the reference output of the voltage amplitude and phase; where k is the proportional coefficient, which is the frequency of the droop output, f g is the grid frequency, and s is a pull operator.

[0032] The improved droop phase angle output is:

[0033] From this a new droop can be obtained: f'=f * -m(P-P * )+k'(f'-f g )

[0034] Transform to get:

[0035] In the formula, P is t...

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Abstract

The invention discloses an island detection method for a droop control grid-connected inverter. The method is implemented specifically according to the following steps: 1, a three-phase grid-connectedinverter main circuit system is built; 2, output active power and reactive power of the three-phase grid-connected inverter are calculated; 3, an improved P-f droop controller with disturbance k(f-f<g>)/s added is utilized to calculate reference output of voltage amplitude and phase; 4, difference between the reference voltage and phase and actual voltage and phase is calculated to obtain an error voltage value as reference input of an outer ring regulator, output of the regulator is reference input of inner ring current, difference between the reference input of the inner ring current and actual current is calculated to obtain an error current value as input of an inner ring regulator, and finally, an output modulation signal is obtained; and 5,the value of |d[delta][theta]/dt|=|k(f-f<g>)| is monitored in real time to perform island judgment. According to the island detection method for a droop control grid-connected inverter, on the basis of a traditional island monitoring droop improvement method, integration is added for the disturbance part, the amplitude of |d[delta][theta]/dt| is increased and stable amplitude is maintained, thereby avoiding island misjudgment.

Description

technical field [0001] The invention relates to the field of grid detection, in particular to a droop control micro grid island monitoring method. Background technique [0002] With the development of renewable energy power generation technology, distributed power generation technology came into being. In recent years, due to the advantages of "plug and play" and no need for communication, droop-controlled inverters are more and more widely used in distributed generation systems. During the operation of the microgrid, there will be two situations of grid connection and islanding. The islanding effect refers to the phenomenon that when the power system stops supplying power due to a fault, the distributed generation system continues to provide active and reactive power to the local load. The islanding is divided into There are planned islands and unplanned islands. Accuracy and speed of monitoring unplanned islands are important. Therefore, it is necessary to study the isl...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): H02J3/38G01R31/00
CPCG01R31/00H02J3/382H02J3/388
Inventor 王晓寰杨庆收张莹冯建周张纯江
Owner YANSHAN UNIV
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