US 12,000,906 B2 · System and method for measuring transformer hot-spot temperature

Abstract

The present disclosure provides a system and a method for measuring hot-spot temperature of a transformer, wherein the measurement system comprises a processor, an oscilloscope and a plurality of ultrasonic sensors, wherein the ultrasonic sensors are oppositely arranged on an outer wall of a transformer oil tank and electrically connected with the oscilloscope, and the oscilloscope is electrically connected with the processor; the ultrasonic sensors receive signals transmitted by the oppositely arranged ultrasonic sensors and transmit them to the oscilloscope. The method, by applying an ultrasonic wave to measure the hot-spot temperature of a transformer in real time, solves the problems that methods in the prior art are susceptible to the external environment, have short service life and cannot correctly measure the internal temperature of the transformer.

Claims9

Dependent claims

A system of measuring a temperature of a transformer, comprising:

a processor, an oscilloscope and a plurality of ultrasonic sensors, wherein the plurality of ultrasonic sensors are oppositely arranged on outer walls of a transformer oil tank and electrically connected with the oscilloscope, and the oscilloscope is electrically connected with the processor;
one ultrasonic sensor of the plurality of ultrasonic sensors receives signals transmitted by an oppositely arranged ultrasonic sensor of the plurality of ultrasonic sensors, and the one ultrasonic sensor transmits the signals received from the oppositely arranged ultrasonic sensor to the oscilloscope.

A method for maintaining a transformer, comprising:

controlling transmission of ultrasonic signals generated by ultrasonic sensors to obtain ultrasonic signals passing through an interior of the transformer;
identifying ultrasonic signals with changed waveforms among obtained ultrasonic signals;
according to positions of the ultrasonic sensors, identifying propagation paths of ultrasonic signals with changed ultrasonic waveforms, and determining an area where multiple propagation paths with changed ultrasonic waveforms overlap with each other;
according to a position of the area and ultrasonic signals passing through the area, constructing a solution matrix of the area based on a radial basis function to calculate a temperature distribution of the area;
adjusting or overhauling the transformer based on the temperature distribution of the area,
wherein
the step of according to the position of the area and the ultrasonic signals passing through the area, constructing the solution matrix of the area based on the radial basis function to calculate the temperature distribution of the area, comprises:
meshing the area into n three-dimensional meshes, a coordinate of a center point of an ith mesh of the n three-dimensional meshes being presented as (xi, yi, zi) wherein n is an integer and i is an integer;
building an area solution matrix based on a radial basis function according to a functional relationship between a sound velocity, a flight time and a sound wave propagation path, wherein the functional relationship is
gk=∫pk(x,y,z)dpk,k=1,2, . . . ,m (1)
where the sound wave propagation path pk, the flight time gk and a reciprocal f(x, y, z) of the sound velocity, a number m of sound wave paths passing through the area;
the reciprocal f(x, y, z) is discretized into a plurality of linear combinations of n basis functions as follows:
f
⁡
(
x
,
y
,
z
)
=
∑
i
=
1
n
ε
i
⁢
φ
i
(
x
,
y
,
z
)
,
(
2
)
wherein εi is an undetermined coefficient and φi(x, y, z) is a radial basis function:
φ
i
(
x
,
y
,
z
)
=
e
-
a
⁢
(
x
-
x
i
)
2
+
(
y
-
y
i
)
2
+
(
z
-
z
i
)
2
,
(
3
)
wherein a is a shape parameter of the radial basis function;
the undetermined coefficient εi in formula (2) is solved, and formulas (1), (2) and (3) are combined as follows:
g
k
=
∑
i
=
1
n
ε
i
⁢
∫
p
k
φ
i
(
x
,
y
,
z
)
⁢
dp
k
=
∑
i
=
1
n
ε
i
⁢
a
ki
,
(
4
)
where aki=ƒpkφi(x, y, z)dpk;
a solution matrix of the area is built as a matrix A=(aki)k=1, . . . ,m;i=a, . . . ,n;
g and ε are defined as g=(g1, . . . , gk)T, ε=(ε1, . . . , εn), and the formula (4) is expressed as:
g=Aε (5);
the solution matrix of the area is solved by reconstructing the matrix A;
and
obtaining the temperature distribution in the area, based on the area solution matrix, using a singular value decomposition (SVD) and an interpolation algorithm, wherein
a reconstructed matrix is decomposed by SVD;
a pseudo inverse of the matrix A is:
A
-
1
=
V
[
Σ
-
1
0
0
0
]
⁢
U
T
,
Σ
-
1
=
diag
(
1
σ
1
,
1
σ
2
,
…
,
1
σ
γ
)
,
where σ1≥σ2≥ . . . ≥σγ≥0 are γ non-zero singular values of the reconstructed matrix, γ is a rank of the reconstructed matrix, and U and V are eigenvectors whose column vectors are orthogonal matrices AAT and AT A respectively;
by the singular value decomposition, a least square solution of formula (5) can be expressed as:
ε
=
∑
i
=
1
p
u
1
T
⁢
t
σ
i
⁢
v
i
,
where p represents a total number of non-zero singular values.

193 more elements

Dependencies are inferred from the claim text.

System and method for measuring transformer hot-spot temperature

Life of this patent

System and method for measuring transformer hot-spot temperature

Life of this patent

Abstract

Claims9