Unbalanced control method for grid-connected inverter multi-target collaborative optimization

A technology of collaborative optimization and balance control, applied in the direction of single-network parallel feeding arrangement, multi-phase network elimination/reduction of asymmetry, AC network circuit, etc. The effect of eliminating secondary instantaneous reactive power and clear structure

Inactive Publication Date: 2015-02-25
CHINA UNIV OF MINING & TECH
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0004] Although the expected control effect can be achieved by calculating the command current for the three independent control targets, it is impossible to make the three coordinated control and smoothly switch from the three states to each other, which is an important constraint in practical applications. factor

Method used

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  • Unbalanced control method for grid-connected inverter multi-target collaborative optimization
  • Unbalanced control method for grid-connected inverter multi-target collaborative optimization
  • Unbalanced control method for grid-connected inverter multi-target collaborative optimization

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Embodiment 1

[0033] The grid-connected inverter multi-objective collaborative optimization method for negative-sequence current amplitude and phase analysis when the power grid is unbalanced in this embodiment is based on the grid-side instantaneous power model, and includes the following steps:

[0034] Step 1: Establish the main circuit and control circuit of the LCL filtered three-phase grid-connected inverter. The main circuit includes the equivalent DC power supply u of the distributed power generation module dc , DC side capacitor C, grid-connected inverter V, output LCL filter. The control circuit adopts the double-closed-loop control strategy of PI voltage outer loop and PR current inner loop, and adopts the capacitive current proportional feedback active damping method to suppress the resonance phenomenon of the LCL filter. The frequency ring method extracts the positive and negative sequence components.

[0035] Step 2: Sampling the voltage of the three-phase grid, the output c...

Embodiment 2

[0061] The multi-objective collaborative optimization method for grid-connected inverters based on the analysis of negative-sequence current amplitude and phase when the power grid is unbalanced in this embodiment is based on the instantaneous power model on the converter side. The fifth step of embodiment 1 is different, and the rest of the steps are the same. The step five of present embodiment 2 is as follows:

[0062] Step five:

[0063] will i 2d +* and i 2q +* In the form of a matrix and the negative sequence command current generation matrix T m Multiply and then multiply by the proportional factor k to get the α, β axis negative sequence command current signal i 2α -* i 2β -* . By adjusting k, the secondary instantaneous active power and secondary instantaneous reactive power of the converter side and the output three-phase current of the AC side can be smoothly adjusted at the same time.

[0064] define u α + , u α - , u β + , u β - is the positive ...

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Abstract

The invention provides an unbalanced control method for grid-connected inverter multi-target collaborative optimization and belongs to a control method for a grid-connected inverter. The unbalanced control method includes the step of analyzing the amplitude and phase of a negative-sequence current and adjusting a scaling factor k to enable the grid-connected inverter to be smoothly switched among multiple targets, the step of establishing the relation between the amplitude and the phase of the current on the basis of suppressing instantaneous active secondary power fluctuation and instantaneous reactive secondary power fluctuation according to an instantaneous power model of a network side and an instantaneous power model of a convertor side to obtain a negative-sequence directive current generated matrix T, and the step of selecting an appropriate scaling factor k with the condition of balancing three-phase alternating currents and suppressing network side instantaneous active power secondary fluctuation and network side instantaneous reactive power secondary fluctuation as a control target so that coordination control of three targets can be achieved under power grid unbalance. According to the method, the principle is simple, the structure is clear, and the expected optimal working condition of the grid-connected inverter can be obtained as long as the parameter k is adjusted.

Description

technical field [0001] The invention relates to a control method of a grid-connected inverter, in particular to an unbalanced control method for multi-objective collaborative optimization of a grid-connected inverter. Background technique [0002] The grid-connected inverter is a bridge connecting the distributed generation unit and the grid. The two influence each other. The current injected by the distributed generation unit into the grid may have harmonics, which may cause the grid-connected inverter to fail to meet the relevant standards, and the grid may also Three-phase unbalanced voltage is provided, which affects the normal operation of the inverter. [0003] Three-phase unbalance is a common fault type in the power grid. When a three-phase unbalanced fault occurs in the grid voltage, two measures are usually taken to ensure that the inverter can still operate normally: increase the DC side capacitance and the AC side inductance to stabilize the DC side voltage and ...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): H02J3/38
CPCH02J3/26H02J3/381
Inventor 耿乙文李小强吴琼李珊珊王凯张雪张雷伍小杰
Owner CHINA UNIV OF MINING & TECH
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