Frequency self-adaptive real-time fractional harmonic wave detection method

Abstract

The invention discloses a frequency self-adaptive real-time fractional harmonic wave detection method. Phase locking is conducted on power grid voltages through a phase locked loop, the power grid voltage frequency fg is obtained, the system control frequency fs is adjusted according to the power grid voltage frequency fg, when the power grid voltage frequency fluctuates, the number of sampling points of a system within the power grid fundamental wave period is kept unchangeable, the function of frequency self-adaptation of an n-harmonic-wave band-pass filter is achieved, and then subtraction is carried out on the input quantity of the n-harmonic-wave band-pass filter to remove mutual interference among all times of harmonic waves. Finally, n harmonic waves of a detected signal are extracted through the n-harmonic-wave band-pass filter, and then the harmonic waves of the detected signal can be accurately detected in a real-time and fractional mode.

Description

technical field [0001] The invention belongs to the technical field of electric power, and more specifically relates to a frequency adaptive real-time fractional harmonic detection method. Background technique [0002] With the wide application of power electronic equipment in industrial, commercial and civil fields, a large amount of reactive and harmonic currents are generated. Harmonic currents will cause a series of problems such as reduced power grid efficiency, failure or damage of sensitive loads, overheating of motors or transformers, and communication interference. Therefore, harmonic detection and suppression has always been one of the hot issues in the power field. [0003] Through the retrieval of the existing domestic and foreign technical literature, it is found that the harmonic detection methods can be mainly divided into two categories: frequency-domain-based detection methods and time-domain-based detection methods. [0004] Asiminoaei L et al. in the lit...

AI Technical Summary

Problems solved by technology

The time-domain harmonic detection method has the following characteristics: 1) It is a real-time detection method, and the dynamic response speed is generally fast; 2) Generally, the fundamental component of the measured signal is detected first, and then the harmonic of the fundamental component is subtracted from the measured signal component, therefore, the algorithm is simple and the amount of calculation is small, but it cannot realize the harmonic sub-detection; the detection method based on the harmonic synchronous rotation transformation realizes the harmonic sub-detection, but it leads to an increase in the calculation amount of the algorithm

In addition, Chinese patent (Patent No. ZL200410018470.7, titled "Harmonic Detection Method Based on Adaptive Neuron Online Tuning") discloses a method that detects the fundamental active component of the load current signal and converts After this signal is deducted from the load current, the detection method of harmonics and reactive components is obtained. At the same time, a larger value is selected for neuron learning in the dynamic process, which improves the speed and accuracy of the algorithm. However, the harmonics cannot be extracted in stages

[0005] When the above harmonic detection methods are all affected by grid frequency fluctuations, the detection accuracy is not high

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