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A Coordinated Control Method for Grid Unbalanced Photovoltaic Inverters Considering Current Limit

A photovoltaic inverter and grid imbalance technology, applied in the field of electrical information, can solve the problems of photovoltaic output drop, current over-limit and other problems, and achieve the effect of good dynamic performance

Active Publication Date: 2021-11-02
CONSTR BRANCH CHONGQING ELECTRIC POWER +1
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  • Abstract
  • Description
  • Claims
  • Application Information

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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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  • A Coordinated Control Method for Grid Unbalanced Photovoltaic Inverters Considering Current Limit
  • A Coordinated Control Method for Grid Unbalanced Photovoltaic Inverters Considering Current Limit
  • A Coordinated Control Method for Grid Unbalanced Photovoltaic Inverters Considering Current Limit

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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] like figure 2 As shown, the output power characteristics of the inverter when the power grid is unbalance...

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Abstract

The invention discloses a coordinated control method for grid unbalanced photovoltaic inverters considering the current limit, first analyzes the separation scheme of positive and negative sequence currents based on the trap, and then quantifies the inverter output under unbalanced grid Power, weighting the quantities that affect photovoltaic active output, reactive output, and current harmonics to obtain the control quantities k and γ, and finally take the minimum active power fluctuation and reactive power fluctuation as the optimization goal, and take the current harmonic distortion rate and output current limit K and γ are optimized for constraints. The invention minimizes active and reactive power fluctuations when the grid has an unbalanced fault and ensures that the current quality is qualified and the current does not exceed the limit, thereby improving the stability and reliability of the control system.

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 Patents(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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