Micro-grid island detection method and system

An island detection and microgrid technology, applied in circuit devices, electrical components, AC network circuits, etc., can solve problems such as large detection blind spots and power quality interference, and reduce harmonic interference, reduce harmonic pollution, and ensure The effect of power quality

Active Publication Date: 2018-10-09
NANJING UNIV OF SCI & TECH
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Problems solved by technology

In the active frequency deviation method (AFD) and the passive detection method (VFD), the detection blind zone and the harmonic interference brought by AFD to the power grid are a pair of contradictions to a certain extent. The monitoring principle of the VFD method is simple and easy to implement. And it

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  • Micro-grid island detection method and system
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  • Micro-grid island detection method and system

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Embodiment 1

[0087] figure 1 Shown is the detection implementation flow chart of the traditional AFD method.

[0088] Through the improved AFD method control strategy, the invention not only reduces the detection blind area, but also improves the influence of the disturbance current waveform on the power quality of the microgrid compared with the traditional AFD. Improved security and reliability in the event of unintended islanding.

[0089] The invention adopts the detection method combining the improved active frequency offset method and the passive method to detect the islanding of the grid-connected inverter. By controlling the output current of the inverter, a small sudden change disturbance is introduced to make the fundamental wave component produce the necessary phase angle offset. When the inverter is connected to the grid, the voltage at the public connection is contained by the grid voltage, so when the current disturbance cannot affect the voltage at the connection point, th...

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Abstract

The invention discloses a micro-grid island detection method and system. The method comprises the following steps that the voltage of a common connection point is collected, and the phase and frequency are obtained; whether an island phenomenon occurs is determined, if YES, the method is completed, and otherwise, a next step is followed; and a disturbance current is input, the voltage of the common connection point is collected again, whether the island phenomenon occurs is determined again, if YES, the method is completed, and otherwise, the first step is returned to. The system comprises a PWM driving module, a collection module and an island detection module, the collection module obtains the voltage, phase and frequency of the common connection point, and sends the voltage, phase and frequency to the island detection to compare the frequency and voltage of the power grid, a detection signal is sent to the PWM driving module, and thus, an inverter of a distributed power generation system is controlled, and the disturbance current waveform corresponding to output of the inverter is generated. Thus, micro-grid island detection can be realized rapidly, the validity of island detection can be still ensured under the condition of distributed energy devices, and interference of harmonic waves is reduced.

Description

technical field [0001] The invention relates to the technical field of micro-grid protection and control in power systems, in particular to a micro-grid island detection method and system. Background technique [0002] With the development of the world economy, the consumption of traditional fossil energy such as oil and coal is increasing, and at the same time, it has caused environmental pollution. In recent years, distributed power generation technology represented by photovoltaic and wind power has developed rapidly. Due to distributed energy Power generation is greatly affected by environmental factors and has the characteristics of intermittent and fluctuating. In order to better organize and manage distributed energy, the concept of microgrid is proposed. A microgrid is a form of grid that combines micro power loads and energy storage devices. It can be integrated into a large grid or work in an island mode. [0003] When the large power grid fails and other factors ...

Claims

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Application Information

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IPC IPC(8): H02J3/38G01R31/08
CPCH02J3/381G01R31/086H02J3/388
Inventor 单逸孟双和孙炜潘飞李成飞
Owner NANJING UNIV OF SCI & TECH
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