Harmonic injection device for harmonic impedance measurement of power grid

Abstract

The invention discloses a harmonic injection device for the harmonic impedance measurement of a power grid. The device comprises a power grid voltage feedback circuit, a signal generation circuit, an amplitude amplification circuit, a power amplification circuit and an interface circuit, wherein the power grid voltage feedback circuit is used for detecting a voltage signal of the power grid, and filtering and inputting the voltage signal to the signal generation circuit; the signal generation circuit is used for synthesizing a harmonic voltage waveform, harmonic voltage frequency, harmonic voltage amplitude, a harmonic voltage waveform phase difference and the phase information of the acquired voltage signal, and generating and outputting a harmonic voltage signal; the amplitude amplification circuit is used for amplifying and outputting the amplitude of the harmonic voltage signal output by a DSP (digital signal processor); the power amplification circuit is used for performing power amplification on the harmonic voltage signal output by the amplitude amplification circuit, and outputting the harmonic voltage signal to the interface circuit; the interface circuit is used for converting the input harmonic voltage signal into a harmonic current signal, and injecting the harmonic current signal into the power grid. According to the harmonic current injection device, harmonic current of which the amplitude, frequency, phase and waveform can be controlled can be injected into the power grid, so that the harmonic impedance measurement accuracy of the power grid is improved.

Description

【Technical field】 [0001] The invention relates to the fields of grid stability analysis and harmonic impedance measurement, in particular to a harmonic injection device for grid harmonic impedance measurement. 【Background technique】 [0002] In the traditional power grid, harmonic impedance is an important parameter for studying the harmonic penetration characteristics of the power grid and filter design. In a power network with many power electronic devices, such as a distributed generation system, the stability of the system can be analyzed accurately and conveniently by using the method of harmonic impedance parameter identification. Therefore, for the power network, how to accurately obtain the relevant harmonic impedance parameters has become a hot research issue. [0003] At present, the main methods of system impedance measurement are switching capacitor method, thyristor branch switching method and harmonic current injection method. The switching capacitor method s...

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Problems solved by technology

The switching capacitor method saves investment, but the harmonics generated by this method are uncontrollable, which may lead to the loss of some harmonic currents, and the amplitude is too small, and the high-frequency components are greatly attenuated; the thyristor branch switching method can control the injection of harmonics The magnitude of the current, but the harmonic frequency injected into the system cannot be accurately controlled, and the high frequency part of the signal is missing; the above two methods cannot accurately measure the harmonic impedance of the microgrid

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