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A Three-phase Power Grid Impedance Measurement Method Using Composite Orthogonal Pulse Injection in Frequency Division

A three-phase power grid, impedance measurement technology, applied in impedance measurement and other directions, can solve problems such as the impact of stable operation of the system, and achieve the effects of reducing measurement complexity, improving power quality, and reducing measurement time

Active Publication Date: 2021-04-13
NANJING UNIV OF AERONAUTICS & ASTRONAUTICS
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Problems solved by technology

However, in the process of superimposing disturbance signals, a large number of harmonics are introduced into the power grid, which affects the stable operation of the system

Method used

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  • A Three-phase Power Grid Impedance Measurement Method Using Composite Orthogonal Pulse Injection in Frequency Division
  • A Three-phase Power Grid Impedance Measurement Method Using Composite Orthogonal Pulse Injection in Frequency Division
  • A Three-phase Power Grid Impedance Measurement Method Using Composite Orthogonal Pulse Injection in Frequency Division

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[0029] The present invention will be described in further detail below in conjunction with examples. However, it should not be understood that the scope of the above subject matter of the present invention is limited to the following embodiments, and all technologies realized based on the content of the present invention belong to the scope of the present invention.

[0030] Such as figure 1 As shown, the present invention is a method for measuring the impedance of a three-phase power grid with composite orthogonal pulse injection in frequency divisions. The impedance measurement scheme includes the following steps:

[0031] (1) Determine the grid impedance measurement bandwidth according to the design parameters of the three-phase inverter;

[0032] (2) Divide the measurement frequency range into frequency bands;

[0033] In step (2), the grid impedance measurement bandwidth range is divided into high frequency band, middle frequency band and low frequency band according to...

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Abstract

The invention provides a method for measuring the impedance of a three-phase power grid by frequency-divided composite orthogonal pulse injection, which belongs to the technical field of power generation systems. The method includes the following steps: (1) Determine the grid impedance measurement bandwidth according to the design parameters of the three-phase inverter; (2) Divide the measurement frequency range into low frequency band, middle frequency band and high frequency band; Design an orthogonal pulse sequence, and superimpose the designed pulses on the given d and q axis currents of the three-phase inverter; (4) Sampling the voltage and current of the PCC point during the pulse injection period of each frequency band and using FFT to convert to frequency domain, and calculate the positive and negative sequence grid impedance; (5) combine the results obtained in step (4) by frequency to obtain the three-phase grid impedance measurement results in a wide frequency range. The invention can realize high-precision measurement of grid impedance in a wider frequency range with fewer measurement times, reduce the harmonic content of grid-connected current during pulse injection, and improve power quality.

Description

technical field [0001] The invention relates to a method for measuring the impedance of a three-phase power grid by frequency-divided composite orthogonal pulse injection, and belongs to the technical field of power generation systems. Background technique [0002] When using the impedance analysis method to study the stability of the grid-connected system, it is not necessary to master the dynamic details of the grid-connected system, only the impedance ratio Z g (s) / Z inv (s) The stability of the system can be analyzed, and on the basis of obtaining the impedance information of the grid, the purpose of enhancing the stability of the system can be achieved by adaptively controlling the impedance of the inverter, so obtaining the impedance information of the grid is very important for the stability of the system Research is critical. However, it is difficult to directly obtain the grid impedance through modeling methods. On the one hand, because there are many equipment an...

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): G01R27/16
Inventor 陈新王赟程黄通王珊珊傅明月周建华刘丹
Owner NANJING UNIV OF AERONAUTICS & ASTRONAUTICS
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