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Detection method of islanding effects with reactive current disturbance based on amplitude changes and device thereof

A technology of amplitude change and island detection, applied in the direction of fault location, etc., can solve the problems of high cost grid side installation, and achieve the effect of avoiding current disturbance and ensuring power quality

Active Publication Date: 2012-07-18
HUBEI TRESS TECH
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  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

[0005] In addition, the external (usually on the grid side) monitoring and communication means of the grid-connected inverter is also a method with high detection performance, but because of its high cost and complex requirements such as grid-side installation, it is only used as a method based on the necessity of use. Alternative methods

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  • Detection method of islanding effects with reactive current disturbance based on amplitude changes and device thereof
  • Detection method of islanding effects with reactive current disturbance based on amplitude changes and device thereof
  • Detection method of islanding effects with reactive current disturbance based on amplitude changes and device thereof

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Embodiment 1

[0027] An islanding effect detection method based on a reactive current disturbance with amplitude change provided by the present invention:

[0028] Step 1: Based on the fundamental reference current signal output by the previous stage control, a 90-degree phase-leading or lagging reactive fundamental current is correspondingly generated, and the current amplitude is proportional to the amplitude of the fundamental reference current;

[0029] Step 2: The reactive fundamental wave current undergoes an amplitude change every power frequency cycle, that is, a reciprocating periodic change of 20% -> 10% -> 0% -> 20% -> 10% -> 0%. The change range of the fundamental wave current should be less than 25% of the fundamental wave reference current;

[0030] Step 3: After the reactive fundamental wave current is output through the closed-loop control of the grid-connected inverter, a voltage will be formed on the output load, and the amplitude change of the reactive fundamental wave cu...

Embodiment 2

[0032] An islanding effect detection method based on a reactive current disturbance with amplitude change provided by the present invention:

[0033] Step 1: Based on the fundamental reference current signal output by the previous stage control, a 90-degree phase-leading or lagging reactive fundamental current is correspondingly generated, and the current amplitude is proportional to the amplitude of the fundamental reference current;

[0034] Step 2: The reactive fundamental wave current undergoes an amplitude change every power frequency cycle, that is, a reciprocating periodic change of 10% -> 5% -> 0% -> 10% -> 5% -> 0%. The change range of the fundamental wave current should be less than 25% of the fundamental wave reference current;

[0035] Step 3: After the reactive fundamental wave current is output through the closed-loop control of the grid-connected inverter, a voltage will be formed on the output load, and the amplitude change of the reactive fundamental wave curr...

Embodiment 3

[0039] A device based on an island effect detection method for reactive current disturbances with amplitude changes, which is sequentially connected by a sensor, a processing control module, and a drive circuit (PWM). The processing control module includes a PLL for processing the feedback signal collected by the sensor Phase-locked loop, reactive current signal generator and digital processor. The PLL phase-locked loop is specifically Phase Locked Loop. The reactive current signal generator is also realized by MCU chip. The digital processor can be produced by Microchip, an American microchip company. The model is dsPIC30F4011 digital processor, the output terminal of the sensor is connected to the PLL phase-locked loop, the output terminal of the PLL phase-locked loop is respectively connected to the digital processor and the reactive current signal generator, and the output terminal of the reactive current signal generator is connected to The digital processor, the PLL phase...

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Abstract

The invention provides a detection method of unintentional islanding effects with reactive current disturbance based on amplitude changes and suitable for a small wind-power or photovoltaic grid-connected inverter and a device of the detection method of the islanding effects with the reactive current disturbance based on the amplitude changes. The detection method does not need to change output work frequency and does not influence output current harmonic. The detection method has the advantages that (1) a method of reactive base wave current injection is utilized so that output of actual active power is not influenced, harmonic current is not generated, and quality of output electric energy is ensured; and (2) the amplitude of reactive current is changed periodically, the islanding effects are judged by judging voltage amplitude change conditions of connection points, and the condition that overlarge current disturbance is injected to meet needs of over-voltage or under voltage is avoided.

Description

technical field [0001] The invention relates to a detection method for grid-connected inverters to prevent unplanned islanding effects, in particular to a method for detecting islanding effects based on reactive current disturbances with amplitude changes and a device thereof. Background technique [0002] The islanding effect is that when the power grid loses voltage, the grid-connected inverter still maintains the state of continuously supplying power to a certain part of the power grid. The island effect can be divided into unplanned island effect and planned island effect. The unplanned islanding effect is an unplanned and uncontrolled islanding effect, while the planned islanding effect is a planned islanding effect according to a pre-configured control strategy. [0003] When the unplanned islanding effect occurs, due to the unknown power supply status of the system, it will cause the following adverse effects: 1. It may endanger the lives of grid line maintenance per...

Claims

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Application Information

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IPC IPC(8): G01R31/08
Inventor 彭景生
Owner HUBEI TRESS TECH
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