Method and device for quickly eliminating ferromagnetic resonance of voltage transformer

Patent metadata

Field	Value
Publication number	US-11264793-B2
Application number	US-201916649438-A
Country	US
Kind code	B2
Filing date	Apr 10, 2019
Priority date	May 4, 2018
Publication date	Mar 1, 2022
Grant date	Mar 1, 2022

Abstract

The present invention discloses a method for quickly eliminating ferromagnetic resonance of a voltage transformer. The method includes: first sampling a three-phase voltage and an open-delta voltage of a voltage transformer; calculating a flux linkage corresponding to a zero-sequence voltage by means of an integral algorithm; and when detecting that ferromagnetic resonance occurs in the mutual inductor, further checking whether the absolute value of the flux linkage corresponding to the zero-sequence voltage or the absolute value of the open-delta voltage respectively falls within a set range, and if yes, starting a secondary resonance elimination loop for resonance elimination. The present invention also discloses a corresponding device for quickly eliminating ferromagnetic resonance of a voltage transformer. The present method and device accurately analyze and control resonance elimination trigger time based on a conventional secondary resonance elimination principle, and can effectively eliminate the impact of the core saturation of a voltage transformer on a resonance elimination process, thereby greatly improving the success probability of single resonance elimination.

First claim

What is claimed is:

1. A method for quickly eliminating ferromagnetic resonance of a voltage transformer, comprising the following steps:
step 1: collecting a three-phase voltage secondary value and an open-delta voltage of a voltage transformer in real time;
step 2: calculating a flux linkage ψ 0 corresponding to a zero-sequence voltage in real time according to the three-phase voltage secondary value or the open-delta voltage collected in real time; and
step 3: when detecting that ferromagnetic resonance occurs in the voltage transformer, further checking whether an absolute value of the flux linkage corresponding to the zero-sequence voltage or an absolute value of the open-delta voltage respectively falls within a set range, if yes, triggering a silicon controlled rectifier resonance elimination loop connected in parallel to both ends of an open-delta winding of the voltage transformer to be quickly turned on, to eliminate ferromagnetic resonance, and if not, not triggering the silicon controlled rectifier resonance elimination loop to be turned on.

2. The method for quickly eliminating ferromagnetic resonance of a voltage transformer according to claim 1 , wherein in the step 2, the flux linkage ψ 0 corresponding to the zero-sequence voltage is calculated by means of the three-phase voltage secondary value or the open-delta voltage with a calculation formula shown as follows:
ψ 0 =−∫( U A +U B +U C ) dt

or ψ 0 =−∫(3 U 0 ) dt

wherein U A , U B , U C , and 3 U 0 are three-phase voltage secondary values and an open-delta voltage, respectively.

3. The method for quickly eliminating ferromagnetic resonance of a voltage transformer according to claim 1 , wherein in the step 3, the ferromagnetic resonance occurring in the voltage transformer comprises fractional-frequency ferromagnetic resonance, fundamental-frequency ferromagnetic resonance, and multiple-frequency ferromagnetic resonance.

4. The method for quickly eliminating ferromagnetic resonance of a voltage transformer according to claim 1 , wherein in the step 3, the absolute value of the flux linkage corresponding to the zero-sequence voltage falling within the set range means that the flux linkage ψ 0 corresponding to the zero-sequence voltage satisfies |ψ 0 |≤K1*ψ N , wherein K1 is a coefficient,

ψ
N

=

U
m

ω

,

U
m

is a rated secondary voltage peak value of the voltage transformer, and ω power-frequency angular frequency.

5. The method for quickly eliminating ferromagnetic resonance of a voltage transformer according to claim 1 , wherein in the step 3, the absolute value of the open-delta voltage falling within the set range means that the absolute value of the open-delta voltage 3 U satisfies |3 U 0 |≥K2*U max , wherein U max is the maximum value of the open-delta voltage collected in the previous resonance period when the resonance is detected, and K2 is a coefficient.

6. The method for quickly eliminating ferromagnetic resonance of a voltage transformer according to claim 1 , wherein in the step 3, a silicon controlled rectifier loop comprises a silicon controlled rectifier capable of being bidirectionally turned on and a resonance elimination resistor connected in series thereto; the silicon controlled rectifier loop is mounted in parallel at the output port of an open-delta loop on the secondary side of the voltage transformer, and is connected in parallel to an open-delta voltage measurement loop.

7. The method for quickly eliminating ferromagnetic resonance of a voltage transformer according to claim 1 , wherein in the step 3, triggering the silicon controlled rectifier loop means issuing a turn-on instruction to a silicon controlled rectifier in the loop, so that the silicon controlled rectifier is in an ON state in both forward and reverse directions.

8. A device for quickly eliminating ferromagnetic resonance of a voltage transformer, comprising a collection unit, a calculation unit, and a detection and resonance elimination unit, wherein:
the collection unit collects a three-phase voltage secondary value and an open-delta voltage of a voltage transformer in real time;
the calculation unit receives measured data of the collection unit, and calculates a flux linkage ψ 0 corresponding to a zero-sequence voltage in real time according to the three-phase voltage secondary value or the open-delta voltage collected in real time; and
the detection and resonance elimination unit receives the measured and calculated data of the collection unit and the calculation unit, and when detecting that ferromagnetic resonance occurs in the voltage transformer, further checks whether the absolute value of the flux linkage corresponding to the zero-sequence voltage or the absolute value of the open-delta voltage respectively falls within a set range, if yes, triggers a silicon controlled rectifier resonance elimination loop connected in parallel to both ends of an open-delta winding of the voltage transformer to be quickly turned on, to eliminate ferromagnetic resonance, and if not, does not trigger the silicon controlled rectifier resonance elimination loop to be turned on.

9. The device for quickly eliminating ferromagnetic resonance of a voltage transformer according to claim 8 , wherein in the calculation unit, the flux linkage ψ 0 corresponding to the zero-sequence voltage is calculated by means of the three-phase voltage secondary value or the open-delta voltage with a calculation formula shown as follows:
ψ 0 =−∫( U A +U B +U C ) dt

or ψ 0 =−∫(3 U 0 ) dt

wherein U A , U B , U C , and 3 U 0 are three-phase voltage secondary values and an open-delta voltage, respectively.

10. The device for quickly eliminating ferromagnetic resonance of a voltage transformer according to claim 8 , wherein in the detection and resonance elimination unit, the absolute value of the flux linkage corresponding to the zero-sequence voltage falling within the set range means that the flux linkage ψ 0 corresponding to the zero-sequence voltage satisfies |ψ 0 |≤K1*ψ N , wherein K1 is a coefficient,

ψ
N

=

U
m

ω

,

U
m

is a rated secondary voltage peak value of the voltage transformer, and ω is power-frequency angular frequency.

11. The device for quickly eliminating ferromagnetic resonance of a voltage transformer according to claim 8 , wherein in the detection and resonance elimination unit, the absolute value of the open-delta voltage falling within the set range means that the absolute value of the open-delta voltage 3 U 0 satisfies |3 U 0 |≥K2*U max , wherein U max is the maximum value of the open-delta voltage collected in the previous resonance period when the resonance is detected, and K2 is a coefficient.

12. The device for quickly eliminating ferromagnetic resonance of a voltage transformer according to claim 8 , where

Assignees

• Nr Electric Co Ltd
• Nr Engineering Co Ltd

Inventors

• Wang Honglin
• Wang Kai
• Zhang Qixue
• Wang Guang
• Chen Jun

Classifications

• G01R15/18

  using inductive devices, e.g. transformers · CPC title

• H02H7/05

  for capacitive voltage transformers, e.g. against resonant conditions · CPC title

• H02H9/007 Primary

  avoiding or damping oscillations, e.g. fenoresonance or travelling waves · CPC title

• H01F27/42

  Circuits specially adapted for the purpose of modifying, or compensating for, electric characteristics of transformers, reactors, or choke coils (circuits for controlling transformers, reactors or choke coils, for the purpose of obtaining a desired output H02P13/00; impedance networks H03H) · CPC title

• H02H7/04

  for transformers · CPC title