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Coordination control method for photovoltaic inverter in grid unbalance of considering current limit value

An unbalanced power grid and photovoltaic inverter technology, applied in the field of electrical information, can solve problems such as photovoltaic output drop and current over-limit, etc., and achieve the effect of small fluctuation of active power and reactive power and good dynamic performance.

Active Publication Date: 2018-11-23
CONSTR BRANCH CHONGQING ELECTRIC POWER +1
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AI Technical Summary

Problems solved by technology

[0005] For the defects or improvement needed in the existing method, the present invention proposes a coordinated control method for photovoltaic inverters in an unbalanced grid considering the current limit to solve the current limit during the coordinated control and the photovoltaic output that only considers the current limit control strategy For the problem of drop, the optimization goal is to minimize active power fluctuation and reactive power fluctuation, and the current harmonic distortion rate and output current limit are constrained conditions, so that the photovoltaic inverter can provide effective real-time feedback when the power grid unbalanced fault occurs. Control strategy, under the condition of ensuring the current quality is qualified and the current does not exceed the limit, seek the optimal solution to minimize the fluctuation of active and reactive power

Method used

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  • Coordination control method for photovoltaic inverter in grid unbalance of considering current limit value
  • Coordination control method for photovoltaic inverter in grid unbalance of considering current limit value
  • Coordination control method for photovoltaic inverter in grid unbalance of considering current limit value

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Embodiment 1

[0056] In this embodiment, a coordinated control method for unbalanced photovoltaic inverters in a power grid considering the current limit includes the following steps:

[0057] 1) Extraction scheme of positive and negative sequence current and voltage when the power grid is unbalanced

[0058] The extraction of positive and negative sequence components of voltage is the premise of realizing unbalanced grid inverter control, and the accuracy of positive and negative sequence components extraction directly affects the performance of the control system. At present, there are many methods of positive and negative sequence component extraction, such as positive and negative sequence extraction technology based on decoupling, positive and negative sequence extraction technology based on orthogonal component, and positive and negative sequence extraction technology based on filtering. Considering that the calculation amount of the first two methods is relatively large, which will a...

Embodiment 2

[0125] This embodiment is based on the unbalanced photovoltaic inverter coordinated control method of the power grid considering the current limit described in the above embodiment, and builds a photovoltaic grid-connected model of the unbalanced control method for simulation testing. The "unbalance" module in the model is based on image 3 The packaged inverter coordination control module is built. The input of this module is the grid voltage signal, the inverter current signal and the reference power signal of the photovoltaic cell.

[0126] The positive and negative sequence separation principle of the notch filter in this embodiment is obtained from the formula (1). The notch filter can realize the separation of positive and negative sequences by filtering specific frequency waveforms, and provide required data for the implementation of subsequent solutions.

[0127] Such as figure 2 As shown, the output power characteristics of the inverter when the power grid is unbala...

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Abstract

The invention discloses a coordination control method for a photovoltaic inverter in grid unbalance of considering a current limit value. The method comprises the steps of firstly analyzing a wave trap-based separation scheme for positive and negative sequence current; quantifying output power of the inverter in an unbalanced grid and weighting variables of affecting photovoltaic active power output, reactive power output and current harmonic to obtain controlled variables k and gamma; and finally optimizing the controlled variables k and gamma by taking minimum active power fluctuation and reactive power fluctuation as optimization objects and a current harmonic distortion rate and an output current limit value as constraint conditions. According to the coordination control method, activepower fluctuation and reactive power fluctuation are minimum under the condition of ensuing that the quality of the current is qualified and the current does not exceed the limit when an unbalance fault occurs in the grid, and the stability and the reliability of a control system are improved.

Description

technical field [0001] The invention relates to the field of electrical information, in particular to a coordinated control method for unbalanced photovoltaic inverters in a power grid considering current limits. Background technique [0002] One of the most common faults in the power system when the power grid is unbalanced. Factors such as the access of high-power single-phase loads, the unbalanced distribution of single-phase loads in the three-phase system, and the randomness of power consumption of single-phase loads will cause grid failure. Unbalanced three-phase voltage, Yang Tongguang, Gui Weihua. A review of grid-connected inverter control strategies under the condition of unbalanced power grid[J]. Chinese Journal of Electrotechnical Society, 2015,30(14):241-246. When the three-phase voltage of the grid is unbalanced, a negative sequence component will be generated in the grid voltage. At this time, due to the lack of control of the negative sequence voltage by the ...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): H02J3/38H02J3/01H02J3/24H02J3/18
CPCH02J3/383H02J3/01H02J3/18H02J3/24H02J2203/20Y02E10/56Y02E40/30Y02E40/40
Inventor 赵晋蒋闻张程柯雷霞邱少引
Owner CONSTR BRANCH CHONGQING ELECTRIC POWER
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