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PRBS disturbance injection-based power grid impedance online identification method and device

A technology of grid impedance and identification method, which is applied in the direction of measuring device, impedance measurement, measuring electricity, etc., can solve problems affecting the test results of grid impedance, and achieve the effect of adaptive control avoidance

Active Publication Date: 2017-09-01
GUANGXI UNIV
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Problems solved by technology

This method has shortcomings, because noise is everywhere, which means that even at non-characteristic frequencies, there are still many noises in the grid, which will seriously affect the grid impedance test results

Method used

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  • PRBS disturbance injection-based power grid impedance online identification method and device
  • PRBS disturbance injection-based power grid impedance online identification method and device
  • PRBS disturbance injection-based power grid impedance online identification method and device

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Embodiment Construction

[0030] The preferred embodiments of the present invention will be described in detail below in conjunction with the accompanying drawings, so that the advantages and features of the present invention can be more easily understood by those skilled in the art, so as to define the protection scope of the present invention more clearly.

[0031] The specific implementation method of this embodiment is as follows:

[0032] (1) In this embodiment, a three-phase grid-connected inverter or a single-phase grid-connected inverter controlled by dq domain current is mainly used to realize the online identification of the power grid. First, the output amplitude reference value I of the inverter current control loop ref (For a three-phase grid-connected inverter, it is the d-axis reference value I dref ) Add a perturbation channel of PRBS:

[0033] The perturbation channel can output the reference value I to the built-in program ref (For a three-phase grid-connected inverter, it is the d...

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Abstract

The present invention relates to the technical field of electrical engineering and discloses a PRBS disturbance injection-based power grid impedance online identification device. The device is mainly composed of a grid-connected inverter, a current loop controller, a sampling device and an impedance identification unit. The device is characterized in that the grid-connected inverter is connected with the current loop controller. When the grid-connected state is stable, the grid-connected inverter injects the PRBS disturbance into the power grid. During the injection process of a PRBS signal, a built-in output voltage THD is fed back to the controller, so that the THD value of the output voltage of the inverter is ensured to be smaller than 5%. The sampling device is connected with the PCC part of the power grid and is used for sampling and recording the voltage and the current at the PCC part of the power grid. The impedance identification unit is used for subjecting the sampled data of the sampling device to DFT analysis, and taking the average value of the amplitude and the average value of the phase of each harmonic component of the voltage and the current during the current sampling period. The method of the invention is high in precision, high in speed, strong in real-time property, wide in frequency range, lower in measuring cost and difficulty, and better in stability.

Description

technical field [0001] The present invention relates to the technical fields of electrical engineering, computer control and power electronics, and more specifically, to a method and device for online identification of grid impedance based on PRBS disturbance injection. Background technique [0002] With the integration of large-scale renewable distributed power sources such as wind power and photovoltaic power generation into the grid, the integration of large-scale electric vehicles, and the continuous increase in the proportion of loads that use power electronic conversion interfaces in the total load of the grid, the power supply and load of the grid Significant changes have taken place in the characteristics, and the characteristics of power electronics in the power system are becoming more and more obvious, which brings new challenges to the safe and stable operation of the power grid. Since grid-connected inverters such as wind power and photovoltaics are difficult to...

Claims

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Application Information

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IPC IPC(8): G01R31/00G01R27/16
CPCG01R27/16G01R31/00Y02E40/40
Inventor 宋绍剑陶云峰刘斌廖碧莲宋春宁
Owner GUANGXI UNIV
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