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Method for realizing network access current of unity power factor of grid-connected inverter and internal anti-islanding

A unit power factor and inverter technology, applied in the direction of single-network parallel feeding arrangement, etc., can solve problems that have not been reported

Inactive Publication Date: 2010-06-16
NANJING UNIV OF AERONAUTICS & ASTRONAUTICS
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  • Abstract
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  • Application Information

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Problems solved by technology

But at present, this method is widely used in the parallel control technology of DC converters and inverters, and its application in current-mode control grid-connected inverters has not been reported.

Method used

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  • Method for realizing network access current of unity power factor of grid-connected inverter and internal anti-islanding
  • Method for realizing network access current of unity power factor of grid-connected inverter and internal anti-islanding
  • Method for realizing network access current of unity power factor of grid-connected inverter and internal anti-islanding

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Embodiment Construction

[0015] Below in conjunction with accompanying drawing, the technical scheme of invention is described in detail:

[0016] attached figure 1 Describes the phase control block diagram of the present invention and the main circuit implemented, which consists of phase difference detection, frequency droop calculation, reference current generation, grid voltage feedforward and proportional-integral controller.

[0017] Incoming grid reference current i o Get the phase reference from the phase locked loop PLL. in K N =1 / K PWM , its closed-loop transfer function is shown in formula (1).

[0018] I O ( s ) = K PWM k p S + K PWM k i LS 2...

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Abstract

The invention discloses a method for realizing a network access current of a unity power factor of a grid-connected inverter and internal anti-islanding, which belongs to control technology of inverters. The method comprises the following steps: phase difference detection, frequency droop calculation, reference current generation, grid voltage feed-forward and a proportional integral controller. A frequency droop algorithm comprises the following steps: performing real-time calculation on a phase difference between the network access current and a grid voltage; multiplying the phase difference by a droop coefficient to obtain a frequency variable quantity; and subtracting the frequency variable quantity from a previous frequency output quantity of the last frequency droop algorithm so as to obtain an output quantity of a new frequency droop algorithm. The method realizes phase control of the network access current of the grid-connected inverter, realizes the network access current of the unity power factor, and internally realizes an anti-islanding measure of frequency drift positive feedback of the grid-connected inverter at the same time. Therefore, the method is of a simple and effective realizing mode.

Description

technical field [0001] The invention relates to a control method for the unit power factor of the grid-connected inverter current entering the grid and the internal anti-islanding, which belongs to the technical field of converter control. Background technique [0002] The energy crisis and environmental degradation have made countries around the world actively develop renewable energy sources including photovoltaics and wind energy. Distributed power generation technology using these energy sources has become an important part of the global energy sustainable development strategy. A research hotspot of new energy distributed power generation is inverter grid-connected control technology. The control methods of grid-connected inverters can be divided into current-type control and voltage-type control. At present, small and medium power single-phase grid-connected inverters generally adopt current-type control. Common methods of current control include proportional-integral...

Claims

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Application Information

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IPC IPC(8): H02J3/38
Inventor 罗运虎阚加荣谢少军肖华锋
Owner NANJING UNIV OF AERONAUTICS & ASTRONAUTICS
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