Live measurement method for three-winding transformer loss based on windowed frequency shift

Patent metadata

Field	Value
Publication number	US-11422175-B2
Application number	US-202017081726-A
Country	US
Kind code	B2
Filing date	Oct 27, 2020
Priority date	May 21, 2020
Publication date	Aug 23, 2022
Grant date	Aug 23, 2022

Abstract

Provided is a live measurement method for three-winding transformer loss based on windowed frequency shift. The method includes: step 1: providing an improved live calculation equation of a three-winding transformer loss; step 2: processing a collected x(t) signal by windowed frequency shift calculation; step 3: solving an amplitude and a phase of the collected x(t) signal via discrete Fourier transform of a frequency shift signal; and step 4: calculating a no-load loss and a load loss of a three-winding transformer.

First claim

What is claimed is:

1. A live measurement method for three-winding transformer loss based on windowed frequency shift, comprising following steps:
step 1 : establishing an improved live calculation equation for the three-winding transformer loss by using a three-winding transformer equivalent circuit, and determining, according to the improved live calculation equation for the three-winding transformer loss, an instantaneous voltage value v 1 of a high-voltage side of a three-winding transformer, an instantaneous current value i 1 of the high-voltage side of the three-winding transformer, an instantaneous reduction value v 2 ′ of a medium-voltage side voltage at the high-voltage side in the three-winding transformer, an instantaneous reduction value i 2 ′ of a medium-voltage side current at the high-voltage side in the three-winding transformer, an instantaneous reduction value v 3 ′ of a low-voltage side voltage of the three-winding transformer at the high-voltage side, and an instantaneous reduction value i 3 ′ of a low-voltage side current of the three-winding transformer at the high-voltage side;
step 2 : calculating, by using a windowing algorithm, windowed discrete-time Fourier transform equations of an instantaneous voltage signal of the high-voltage side of the three-winding transformer, an instantaneous current signal of the high-voltage side of the three-winding transformer, an instantaneous reduction signal of the medium-voltage side voltage at the high-voltage side in the three-winding transformer, an instantaneous reduction signal of the medium-voltage side current at the high-voltage side in the three-winding transformer, an instantaneous reduction signal of the low-voltage side voltage of the three-winding transformer at the high-voltage side, and an instantaneous reduction signal of the low-voltage side current of the three-winding transformer at the high-voltage side;
step 3 : performing frequency shift processing on the windowed discrete-time Fourier transform equations obtained in the step 2 , and performing Fourier transform on the frequency-shifted discrete-time Fourier transform equations to obtain amplitudes and phases of the instantaneous voltage signal of the high-voltage side of the three-winding transformer, the instantaneous current signal of the high-voltage side of the three-winding transformer, the instantaneous reduction signal of the medium-voltage side voltage at the high-voltage side in the three-winding transformer, the instantaneous reduction signal of the medium-voltage side current at the high-voltage side in the three-winding transformer, the instantaneous reduction signal of the low-voltage side voltage of the three-winding transformer at the high-voltage side, and the instantaneous reduction signal of the low-voltage side current of the three-winding transformer at the high-voltage side; and
step 4 : converting the amplitudes and the phases of the instantaneous voltage signal of the high-voltage side of the three-winding transformer, the instantaneous current signal of the high-voltage side of the three-winding transformer, the instantaneous reduction signal of the medium-voltage side voltage at the high-voltage side in the three-winding transformer, the instantaneous reduction signal of the medium-voltage side current at the high-voltage side in the three-winding transformer, the instantaneous reduction signal of the low-voltage side voltage of the three-winding transformer at the high-voltage side, and the instantaneous reduction signal of the low-voltage side current of the three-winding transformer at the high-voltage side into phasor values, and calculating a no-load loss and a load loss of the three-winding transformer based on the phasor values by using a phasor method;
wherein the live measurement method for three-winding transformer loss based on windowed frequency shift further comprises:
determining an operating state of the three-winding transformer according to the no-load loss and the load loss of the three-winding transformer.

2. The live measurement method for three-winding transformer loss based on windowed frequency shift of claim 1 , wherein
the step 1 comprises following steps:
step 101 : establishing the three-winding transformer equivalent circuit, and in the three-winding transformer equivalent circuit, setting Z 1 to an impedance of a high-voltage winding, Z 2 ′ to a reduction value of an impedance of a middle-voltage winding at the high-voltage side, Z 3 ′ to a reduction value of an impedance of a low-voltage winding at the high-voltage side, Z m to an excitation impedance, v 1 to the instantaneous voltage value of the high-voltage side, i 1 to the instantaneous current value of the high-voltage side, v 2 ′ to the instantaneous reduction value of a medium-voltage side voltage at the high-voltage side, i 2 ′ to the instantaneous reduction value of a medium-voltage side current at the high-voltage side, v 3 ′ to the instantaneous reduction value of a low-voltage side voltage at the high-voltage side, i 3 ′ to the instantaneous reduction value of a low-voltage side current at the high-voltage side, and i m to an excitation current;
step 102 : obtaining a calculation equation for a no-load loss and a load loss in three-winding transformer live detection in the presence of a simplified equivalent circuit,

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Assignees

• State Grid Jiangsu Electric Power Co Ltd
• State Grid Jiangsu Electric Power Co Ltd Marketing Center

Inventors

• Huang Qifeng
• Lu Xiaoquan
• Yang Shihai
• Chen Mingming
• Li Zhixin
• Li Bo
• Su Huiling
• Cao Xiaodong
• Chen Yuqin
• Cheng Hanmiao
• Liu Tianchang
• Huang Yixuan
• Fang Kaijie

Classifications

• G01R31/62 Primary

  Testing of transformers · CPC title

• G01R27/2694 Primary

  Measuring dielectric loss, e.g. loss angle, loss factor or power factor · CPC title

• G01R31/00 Primary

  Arrangements for testing electric properties; Arrangements for locating electric faults; Arrangements for electrical testing characterised by what is being tested not provided for elsewhere ({measuring superconductive properties G01R33/1238;} testing line transmission systems H04B3/46; testing or measuring semiconductors or solid state devices during manufacture {H10P74/00}) · CPC title