Device and method for harmonic impedance measurement of micro-grid

Abstract

The invention discloses a device and a method for the harmonic impedance measurement of a micro-grid. The device comprises a harmonic current source injection device, a harmonic voltage and harmonic current detection device, a data acquisition device and an upper computer, wherein the harmonic current source injection device is used for injecting harmonic current into the grid; the harmonic voltage and harmonic current detection circuit is used for detecting the magnetic harmonic voltage and harmonic current in the grid before and after the harmonic current is injected into the micro-grid; the data acquisition device is used for sampling a signal detected by the harmonic voltage and harmonic current detection circuit, and transmitting data to the upper computer; the upper computer is used for processing the sampled signal, calculating the variations of the harmonic voltage and the harmonic current, and calculating the harmonic impedance of each part of the micro-grid. According to device and the method, harmonic current of which the amplitude, frequency, phase and waveform can be controlled can be injected into the grid through the harmonic current source injection device, so that the harmonic impedance measurement accuracy of the grid is improved.

Description

【Technical field】 [0001] The invention relates to the field of micro-grids, in particular to a device and method for measuring harmonic impedance of a micro-grid. 【Background technique】 [0002] The microgrid contains a variety of distributed power sources, and most of the distributed power sources are connected to the microgrid through power electronic converters. Interactions between power electronic converters and between power electronic converters and the grid can greatly degrade the stability of a microgrid system. Therefore, the stability of the system must be considered in the design and operation of the microgrid. The stability of the system is closely related to the harmonic impedance parameters of the system. It is a research hotspot today to analyze the stability of the system using the method of harmonic impedance parameter identification. Particularly important. [0003] At present, the main methods of system impedance measurement are switching capacitor met...

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Problems solved by technology

However, this method is affected by the switching frequency of the switching tube, and the injected harmonic current is generally below 1KHz

In some specific studies, such as the harmonic impedance measurement of the three-phase AC system, it is necessary to measure the harmonic impedance matrix of the system in the dq coordinate system. At this time, it is often necessary to inject a multi-signal modulation into the system For complex signals, PWM modulation often cannot meet the requirements at this time

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