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

Abstract

The present invention discloses a system side harmonic impedance estimation method and system based on the minimum variance criterion. The method includes the following steps: S1: Sampling at a common connection point to obtain sampling data, and segmenting the sampling data into hourly segments; The sampled data includes a current value and a voltage value; the small segment is a period whose length is less than 10% of the total length of the sampled data; S2: the segmented sampled data is established according to the minimum variance criterion of the system side harmonic impedance variance minimum function; S3 : Solving the minimum variance function according to the formula method to obtain the harmonic impedance of the system side; the system includes a sampling unit, a segmentation unit, a construction unit and a solution unit. The present invention assumes that it conforms to the law of harmonic impedance change during the actual operation of the system, and can track the change of harmonic impedance within a small period. Compared with the traditional method based on the assumption that the system harmonic impedance remains unchanged, the present invention estimates the changing system impedance more quickly to be accurate.

Description

technical field [0001] The invention relates to the research field of system harmonic impedance estimation, in particular to a system-side harmonic impedance estimation method and system based on the minimum variance criterion. Background technique [0002] With the power electronicization of the power grid, the harm caused by the harmonic problem is becoming more and more prominent, which will cause harm to the economic and safe operation of the power grid. It is necessary to analyze and control the harmonic. The equivalent circuit model is usually used, 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 treatment in the power grid is the accurate estimation of the harmonic impedance at the common connection point. [0003] However, most of the existing harmonic impedance estimation methods are based on the following assumptions: the b...

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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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