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Smooth switching control method for operating mode of micro-grid inverter of different capacity micro sources

A technology of operation mode and control method, which is applied in the direction of single-network parallel feeding arrangement, energy industry, electrical components, etc., can solve the problems of smooth switching, in-depth and full elaboration, and achieve fast dynamic response, reduce circulation, and stability sex high effect

Inactive Publication Date: 2015-04-29
STATE GRID CORP OF CHINA +1
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Benefits of technology

This technology allows an alternator (AC) controller to operate with multiple sources at once without interfered by each other or affecting its performance significantly during certain conditions such as being connected into one mode while disconnecting another mode. It also improves upon existing techniques used for AC systems that use resistive elements like varistors but it has several technical benefits over traditional approaches.

Problems solved by technology

Technological Problem addressed in this patents relate to improving efficient power transmission and utilization capabilities in multiple griddled (micro) generators integrated into one small area called a miniature ground station. Current methods such as synchronous rectification cannot achieve these goals because they require complex calculations involving both analog and digital components.

Method used

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  • Smooth switching control method for operating mode of micro-grid inverter of different capacity micro sources
  • Smooth switching control method for operating mode of micro-grid inverter of different capacity micro sources
  • Smooth switching control method for operating mode of micro-grid inverter of different capacity micro sources

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Experimental program
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Effect test

Embodiment 1

[0075] A control method for smoothly switching operation modes of micro-source micro-grid inverters with different capacities. The method operates in a micro-grid composed of several micro-sources with different capacities. The micro-grid includes several distributed power generation units, and the distributed power generation unit It includes a micro-source connected in sequence, an H-bridge inverter circuit, and an LC filter circuit. The LC filter circuit is connected to an AC busbar through a connecting line, the AC busbar is connected to a load, and is also connected to the power grid. The specific steps include:

[0076] (1) The load switch is closed, and the island operation switch S 1 Closed, the inverter starts the island operation mode;

[0077] (2) The load switch is disconnected, and the island operation switch S 1 disconnected, the presynchronized switch S 2 and grid-connected operation switch S 3 Closed, the grid-connected switch is closed, and pre-synchronizat...

Embodiment 2

[0083] According to the smooth switching control method described in Embodiment 1, it is further defined as, in step (1), the load switch is closed, and the island operation switch S 1 Closed, the inverter starts the island operation mode, the operation control method of the micro-source micro-grid inverter with different capacities in the island operation mode, the specific control process includes:

[0084] a. According to the filter capacitor voltage u c , filter inductor current i L , to calculate the active power P and reactive power Q in the island operation mode, the calculation formula is as follows:

[0085] P = 1 N Σ k = 1 N u c ...

Embodiment 3

[0100] According to the smooth switching control method described in Embodiment 1, it is further defined that in step (2), during pre-synchronization control, the calculation step of the reference voltage angular frequency ω is:

[0101] h, to grid voltage u g , filter capacitor voltage u c Carry out frequency detection separately to obtain grid voltage angular frequency ω grid and filter capacitor voltage angular frequency ω inv ;

[0102] i. Grid voltage angular frequency ω grid and filter capacitor voltage angular frequency ω inv The difference is adjusted and controlled by PI to get Δω synch :

[0103] Δω synch =k pω (ω grid -ω inv )+k iω ∫(ω grid -ω inv )dt

[0104] Among them, k pω is the proportional coefficient of PI adjustment, k iω Integral coefficient adjusted for PI;

[0105] j. According to grid voltage u g , Grid-connected current i g , to calculate the active power P in grid-connected operation mode g and reactive power Q g :

[0106] ...

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Abstract

The invention relates to a smooth switching control method for an operating mode of a micro-grid inverter of different capacity micro sources. The method is applied to a micro-grid consisting of multiple different capacity micro sources. The method comprises the following steps: by virtue of switching among different switches, realizing smooth switching of an inverter control method under island/grid-connected operating modes, wherein the island operation is controlled by robust V-f based on capacitive equivalent output impedance so as to generate the voltage reference quantity, and the grid-connected operation is controlled by adopting PQ; adding a pre-synchronization link to be used for controlling the inverter output voltage to trace the power grid voltage when the inverter is switched from island operation to the grid-connected operation, and ensuring that the grid-connected operation is smoothly finished; introducing virtual impedance, designing the equivalent output impedance of the inverter to be capacitive, reducing loop current between parallel inverters, and well realizing power distribution among different capacity micro sources; and adopting double-loop control of the outer voltage loop and inner current loop, wherein the outer voltage loop is controlled by PI, and the inner current loop is controlled by dead beat. Therefore, the system is high in stability and high in dynamic response speed.

Description

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Claims

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Application Information

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Owner STATE GRID CORP OF CHINA
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