System side harmonic impedance estimation method and system based on variance minimum criterion

Abstract

The invention discloses a system side harmonic impedance estimation method and a system based on a variance minimum criterion, and the method comprises the following steps: S1, carrying out the sampling at a common connection point, obtaining sampling data, and carrying out the segmentation of the sampling data according to hour segments; wherein the sampling data comprises a current value and a voltage value; wherein the hour segment is a time segment of which the length is less than 10% of the total length of the sampling data; S2, establishing a system side harmonic impedance variance minimum function for the segmented sampling data according to a variance minimum criterion; S3, solving the variance minimum function according to a matching method, and obtaining system side harmonic impedance; the system comprises a sampling unit, a segmentation unit, a construction unit and a solving unit. According to the method, it is assumed that the harmonic impedance change rule during actual operation of the system is met, the harmonic impedance change can be tracked within an hour period, and compared with a traditional method based on the assumption that the harmonic impedance of the system is not changed, the changed system impedance is estimated more accurately.

Description

Technical field [0001] The present invention relates to the field of system harmonic impedance estimation research, in particular to a system side harmonic impedance estimation method and system based on a minimum variance criterion. Background technique [0002] With the power electronics of the power grid, the harm caused by harmonic problems has become increasingly prominent, causing harm to the economic and safe operation of the power grid. It is necessary to analyze and control harmonics. The equivalent circuit model is usually adopted, that is, a common connection point (PCC) is selected, and the circuits on both sides of the PCC are replaced with Norton equivalent circuits. Furthermore, the premise of harmonic control and governance in the power grid is an accurate estimation of the harmonic impedance at the public connection point. [0003] However, the existing harmonic impedance estimation methods are mostly based on the following assumptions: the background harmonics ar...

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Problems solved by technology

[0004] The technical problem to be solved by the present invention is that when applied to actual engineering scenarios, the assumptions of existing harmonic impedance estimation methods may not be established, resulting in large errors in estimation results. The purpose is to provide a system-side harmonic impedance estimation method based on the minimum variance criterion and system to solve the above problems

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