Detecting method of self-adaptive frequency tracking current

Abstract

The invention discloses a frequency dividing detecting method of a self-adaptive frequency tracking current based on improved extended Prony's spectral estimation. The method comprises the steps of enabling a load current to approach a group of sampling data sequences {in} with equally spaced distance by using N index combinations with amplitudes Bk, phases theta k and frequencies fk according to an extended Prony's spectral estimation method; optimizing the frequency fk of an electric conductance matrix in the extended Prony's spectral estimation on line by using an LMS algorithm in a self-adaptive adjusting algorithm; and figuring out an optimal solution xk under the condition to obtain amplitudes and phases of a fundamental wave and each-order harmonic wave so that a mean square difference Epsilon (n) of an error between an output and a self-adaptive adjusting result is expected to be minimum. By using the detecting method disclosed by the invention, components to be detected can be fast and accurately figured out under the conditions of frequency variation and fundamental current mutation; moreover, the detecting method can also be applied to fast detection of single-order harmonic waves; small error and strong real-time property are obtained and actual application requirements are satisfied.

Description

technical field [0001] The invention relates to an adaptive frequency tracking current frequency division detection method based on improved extended Prony spectrum estimation. Background technique [0002] The first problem to be solved in power system harmonic control is harmonic detection. The detection method of active power filter compensation current generally does not need to decompose each harmonic component, but only needs to detect the total higher harmonics and reactive power distortion current except the fundamental active current, and accurately and real-time It detects the transiently changing distorted current in the power grid, and provides a reference signal for the active power filter control system to perform accurate compensation. [0003] The current detection methods of active power filters mainly include band-stop frequency selection method, Fryze time-domain analysis method, fast Fourier analysis method, instantaneous reactive power theory method, wa...

AI Technical Summary

Problems solved by technology

But they all have problems that are difficult to overcome: the detection system is open-loop and has a fixed frequency, so it is sensitive to changes in component parameters and grid frequency; ground tracking detection

Nowadays, more harmonic detection methods based on instantaneous reactive power can be realized by analog circuits, and the real-time performance is good, but the circuit is complicated, a large number of multipliers are needed, it is not easy to adjust, the amount of calculation is large, the vector transformation is complicated, and low-pass filtering The design performance of the algorithm directly affects the harmonic compensation performance of the active power filter and has a strong dependence on the standard sine-cosine signal (which is difficult to actually generate); in addition, the existing detection algorithms rarely take into account the actual situation The fundamental current is much larger than the harmonic current. The influence of fundamental current fluctuations on harmonic current detection; and changes in generator output, load and system structure in the enterprise distribution network will cause the initial phase of the measured voltage signal Therefore, according to the real-time and accuracy requirements of the reference harmonic current signal acquisition process and the processor part, it is hoped that the detection algorithm will have the characteristics of small amount of calculation and easy implementation. The structure and working principle of the high-power single-injection active power filter for governance are compromised between the detection accuracy and the fast response performance of the detection. The present invention proposes a method based on improved extended Prony spectrum estimation The adaptive frequency tracking current frequency division detection method can not only quickly and accurately obtain the components to be detected in the case of frequency changes and fundamental current mutations, but also can be applied to the rapid detection of single harmonics

Images