CN103457241A - Transformer interior failure recognition post-detection-simulation method based on coupling inductance port characteristics - Google Patents
Transformer interior failure recognition post-detection-simulation method based on coupling inductance port characteristics Download PDFInfo
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Abstract
The invention relates to a transformer interior failure recognition post-detection-simulation method based on the coupling inductance port characteristics, and belongs to the technical field of transformer relay protection. The transformer interior failure recognition post-detection-simulation method comprises the steps of when a power transmission system containing a transformer breaks down, in a short-time window, respectively and actually measuring the voltages u1and u2 and the currents i1 and i2 at the primary side leading-out end and the secondary side leading-out end of the transformer, simulating and computing the voltage of the secondary side leading-out end according to an electromagnetic coupling relation of the transformer, then comparing the waveform of the simulated voltage at the secondary side leading-out end with the waveform of the actually measured voltage u2, computing the association coefficient r between the waveform of the simulated voltage and the waveform of the actually measured voltage u2, recognizing whether interior failure occurs on the transformer or not according to the similarity degree, namely the association coefficient r, of the waveform of the simulated voltage and the waveform of the actually measured voltage u2. According to the transformer interior failure recognition post-detection-simulation method, whether the interior failure occurs on the transformer or not can be accurately and rapidly recognized, influences of excitation flashy flow are avoided, the sensitivity is high, and the reliability is good.
Description
Technical field
The present invention relates to analogy method after a kind of survey of power transformer interior fault based on coupling inductance port identity identification, belong to the transformer relay protecting technical field.
Background technology
Along with building up in China the system for ultra-high voltage transmission that moves and building, increasing superhigh pressure remote conveying electric system puts into operation; large volume ultrahigh pressure in system, extra-high voltage transformer, by increasing, are had higher requirement to reliability and the rapidity of tranformer protection.Data shows, 220kV and above tranformer protection performance factor (70 ~ 80%) are far below the performance factor (99.07%) of route protection, therefore in the urgent need to tranformer protection being done to further research, development and improvement at present.
In transformer differential protection, how distinguishing magnetizing inrush current and internal fault current is intrinsic, a unavoidable difficult problem.At present, the protection scheme that does not rely on the magnetizing inrush current wave character mainly contains magnetic flux characteristic method of identification, Equivalent Circuit Parameter differential method, the algorithm based on transformer model etc.Above each principle has been jumped out the framework of differential protection fully, has avoided the impact of magnetizing inrush current, but still has very large deficiency.The protection of using electric current, two electric parameters of voltage in every case all needs known transformer both sides winding parameter, needs to introduce complicated parameter identification method, easily causes the problems such as numerical value vibration.
Summary of the invention
The technical problem to be solved in the present invention is to improve transformer to identify correctly, rapidly the ability of internal fault external fault, proposes after a kind of transformer internal fault external fault based on the coupling inductance port identity is surveyed to simulate recognition methods.
Technical scheme of the present invention is: analogy method after a kind of survey of the power transformer interior fault identification based on the coupling inductance port identity, when the transmission system containing transformer breaks down, in the short time window, survey respectively the voltage of transformer primary side leading-out terminal and secondary side leading-out terminal
u 1 , u 2and electric current
i 1 , i 2, according to the electromagnetic coupled relation of transformer, the voltage of analog computation secondary side leading-out terminal
, then by the analog voltage of secondary side leading-out terminal
with actual measurement voltage
u 2waveform compare, calculate the coefficient correlation of the two waveform
r, according to the similarity degree of both waveforms, be coefficient correlation
rthe size identification transformer whether internal fault occurs.
The concrete steps of this method are as follows:
(1) when the transmission system containing transformer breaks down, in the short time window, survey respectively the voltage of transformer primary side leading-out terminal and secondary side leading-out terminal
u 1 , u 2and electric current
i 1 , i 2, according to ideal transformer, (be under lossless condition, the coil-block of transformer value is less usually, can ignore, and thinks
r 1=
r 2=0) circuit model, analyze the voltage-to-current equation (voltage-to-current is tie-in equation) that obtains the coupling inductance port identity:
In formula,
l 11,
l 22for each side winding self-induction
, L 12for mutual inductance, simultaneous formula (1), formula (2) cancellation mutual inductance
l 12, obtain analog computation secondary side outlet voltage
computing formula as follows:
Wherein,
, in formula
i mi for exciting current, ω is angular frequency;
Voltage according to above-mentioned formula analog computation secondary side leading-out terminal
;
(2) calculate the analog voltage of secondary side leading-out terminal
with actual measurement voltage
u 2the coefficient correlation of waveform
r:
（4）
In formula, k=1,2,3...... N, N is the sampled data length in short time-window;
(3) according to the coefficient correlation calculated
r, whether the identification transformer internal fault occurs;
When
r≤0 o'clock is the transformer troubles inside the sample space;
When
r>0 o'clock is the transformer external area error.
When described measuring transformer one secondary side outlet voltage, electric current, the length of short time window is 5ms, and sample frequency is 20kHz.
Principle of the present invention is:
1, the ideal transformer model based on coupling inductance
Take single-phase transformer as example, and the circuit model of its lossless transformer is as Fig. 4, and according to the computational methods of Coupled Inductor Circuit, its magnetic flux chain equation is
This is the fundamental equation of analysis and research coupling inductance, under lossless condition, directly to the equation differentiate, just can obtain the voltage-to-current equation (voltage-to-current is tie-in equation) of statement coupling inductance port identity:
（4）
Above two formulas of simultaneous, and cancellation
l 12 , obtain analog computation secondary side voltage
computing formula as follows:
Wherein,
,
, i.e. self-induction
, in formula
i mi for exciting current, ω is angular frequency.
During the transformer external fault, the transformer parameters does not all change, the unique steady of transformer model, the secondary side voltage that utilizes formula (5) analog computation to obtain
with actual measurement voltage
u 2the waveform height is similar.During transformer generation internal fault (turn-to-turn fault, fault, phase-to phase fault etc.) all over the ground, the transformer internal structure changes, and its equivalent-circuit model changes thereupon, and shown in formula (5), equilibrium relation will be broken.Now, if utilize by force formula (5) to carry out computing, the secondary side voltage that analog computation obtains
with actual measurement voltage
u 2great deviation will appear.When magnetizing inrush current and overexcitation appear in transformer, though constantly advance and retreat are saturated for the meeting of static exciter branch road, its not change of inner parameter structure, thereby utilize the circuit model while normally moving still can correctly simulate secondary side line mode voltage.
From above analysis, the matching degree of measured signal and benchmark transformer model, also be embodied on the difference of the voltage waveform of surveying voltage waveform and analog computation, therefore definable uniformity in waveform coefficient
rmeasure the matching degree of measured signal and benchmark transformer model, form the criterion of identification transformer internal fault external fault
2, utilize and survey the coefficient correlation that internal fault external fault identification is carried out in rear simulation
On the basis of calculating analog current, can, by calculating the coefficient correlation of analog current and measured current, judge internal fault external fault.That is, utilize coefficient correlation to portray the degree of correlation of analog current and measured current, the identical criterion of structure alternating current circuit internal fault external fault.
By signal
f(
t) and
g(
t) the strict difinition of cross-correlation function as follows:
In formula,
tit is average time.Cross-correlation function characterizes the time average of the product of two signals.
If
f(
t) and
g(
t) be the cycle to be
t 0periodic signal, above formula can be expressed as:
By the correlation function discretization, and the impact of eliminating signal amplitude, related operation is done to normalization.For discrete measured current signal
i(
k) and analog current
, correlation function can be expressed as:
When j gets zero, above formula can be expressed as:
Thus, the coefficient correlation of analog current value and measured current value can be expressed as:
（10）
In formula, k=1,2,3...... N, N is the sampled data length in short time-window,
rfor cross-correlation coefficient.
rinterval be [1 ,+1] ,+1 means two signal 100% positive correlations ,-1 means two signal 100% negative correlation.
3, the transformer inside and outside fault based on simulation after surveying is screened
When the transmission system containing transformer breaks down, in the short time window, survey respectively the voltage of transformer primary side leading-out terminal and secondary side leading-out terminal
u 1 , u 2and electric current
i 1 , i 2, according to the electromagnetic coupled relation of transformer, the voltage of analog computation secondary side leading-out terminal
, then by the analog voltage of secondary side leading-out terminal
with actual measurement voltage
u 2waveform compare, according to formula
calculate analog voltage
with actual measurement voltage
u 2waveform correlation coefficient
rif, be assumed to be very, measured current waveform and the positive correlation of analog current waveform, and, when being assumed to be fictitious time, measured current waveform and analog current different wave shape are larger, and show as negative correlation.Concrete criterion is as follows:
When
r≤0 o'clock is the transformer troubles inside the sample space;
When
r>0 o'clock is the transformer external area error.
The invention has the beneficial effects as follows:
(1) the present invention is based on the transformer model of coupling inductance, the voltage-to-current equation of the application coupling inductance port identity analog voltage formula of deriving, can identify the transformer internal fault external fault reliably, is not subject to the impact of magnetizing inrush current.
(2) sample frequency of the present invention is 20kHz, meets current hardware condition, and easily realize at scene.Time window is very short, and time window is 5ms, can screen fast internal fault external fault, realizes ultrahigh speed starting protection element.
(3) the present invention adopt and survey after the internal fault external fault recognizer essence of simulation be the boundary element algorithm, transmission to client information, be only the polarity of coefficient correlation, logarithm value calculating be beneficial to hardware development.
The accompanying drawing explanation
Fig. 1 is the circuit diagram of ideal transformer of the present invention;
Fig. 2 is transmission system structural representation of the present invention, and k1, k2 are respectively at secondary side bus exit single phase ground fault and secondary side winding single phase ground fault;
Fig. 3 is transmission system single phase ground fault of the present invention when occurring in secondary side bus exit (k1 point place in Fig. 2), transition resistance and being 50 Ω, secondary side actual measurement voltage
u 2with analog voltage
oscillogram;
Fig. 4 is that transmission system single phase ground fault of the present invention occurs on secondary side winding when (k1 point place in Fig. 2), transition resistance are 50 Ω, secondary side actual measurement voltage
u 2with analog voltage
oscillogram.
Embodiment
Below in conjunction with the drawings and specific embodiments, the invention will be further described.
Analogy method after a kind of survey of the power transformer interior fault identification based on the coupling inductance port identity, when the transmission system containing transformer breaks down, in the short time window, survey respectively the voltage of transformer primary side leading-out terminal and secondary side leading-out terminal
u 1 , u 2and electric current
i 1 , i 2, according to the electromagnetic coupled relation of transformer, the voltage of analog computation secondary side leading-out terminal
, then by the analog voltage of secondary side leading-out terminal
with actual measurement voltage
u 2waveform compare, calculate the coefficient correlation of the two waveform
r, according to the similarity degree of both waveforms, be coefficient correlation
rthe size identification transformer whether internal fault occurs.
The concrete steps of this method are as follows:
(1) when the transmission system containing transformer breaks down, in the short time window, survey respectively the voltage of transformer primary side leading-out terminal and secondary side leading-out terminal
u 1 , u 2and electric current
i 1 , i 2, according to the circuit model of ideal transformer (being under lossless condition), analyze the voltage-to-current equation (voltage-to-current is tie-in equation) that obtains the coupling inductance port identity:
（2）
In formula,
l 11,
l 22for each side winding self-induction
, L 12for mutual inductance, simultaneous formula (1), formula (2) cancellation mutual inductance
l 12, obtain analog computation secondary side outlet voltage
computing formula as follows:
（3）
Wherein,
, in formula
i mi for exciting current, ω is angular frequency;
Voltage according to above-mentioned formula analog computation secondary side leading-out terminal
;
(2) calculate the analog voltage of secondary side leading-out terminal
with actual measurement voltage
u 2the coefficient correlation of waveform
r:
In formula, k=1,2,3...... N, N is the sampled data length in short time-window;
(3) according to the coefficient correlation calculated
r, whether the identification transformer internal fault occurs;
When
r≤0 o'clock is the transformer troubles inside the sample space;
When
r>0 o'clock is the transformer external area error.
When described measuring transformer one secondary side outlet voltage, electric current, the length of short time window is 5ms, and sample frequency is 20kHz.
Execution mode one: the structure chart of 38.5/525kV double winding three-phase voltage increasing transformer is as Fig. 1, transformer parameter is as follows: three-phase transformer is formed by connecting by 3 single-phase transformers, transformer voltage ratio is 38.5 kV/525 kV, both sides leakage inductance 0.524mH, ignore winding resistance, sample frequency is 20 kHz.Single phase ground fault (as k1 point place in Fig. 2) occurs in transformer secondary side bus exit, and transition resistance is 50 Ω.
(1), in the time window of 5ms, survey respectively the voltage of transformer primary side leading-out terminal and secondary side leading-out terminal
u 1 , u 2and electric current
i 1 , i 2, utilize the equivalent electric circuit under the transformer accidental conditions to calculate analog voltage
Then relatively voltage is surveyed in the secondary side exit
u 2waveform and secondary side exit analog voltage
the similarity degree of waveform (as Fig. 3), and according to formula
, calculate analog voltage
with measured current
u 2the coefficient correlation of waveform
r;
(2) differentiate internal fault external fault according to coefficient correlation.By calculating, obtain analog current
with measured current
u 2the coefficient correlation of waveform
r=0.9860>0, therefore be judged as the transmission line external area error.
Execution mode two: the structure chart of 38.5/525kV double winding three-phase voltage increasing transformer is as Fig. 1, and transformer parameter is with embodiment 1.
Circuit Fault on Secondary Transformer winding generation single phase ground fault (as k2 point place in Fig. 2), transition resistance is 50 Ω.
After transmission system breaks down, press the method that embodiment 1 is identical, analog computation Circuit Fault on Secondary Transformer exit voltage
, then compare itself and actual measurement voltage
the similarity degree of waveform (as Fig. 4), calculate analog voltage
with actual measurement voltage
the correlation coefficient r of waveform=-0.6028<0, therefore be judged as the transformer troubles inside the sample space.
The above is explained in detail the specific embodiment of the present invention by reference to the accompanying drawings, but the present invention is not limited to above-mentioned execution mode, in the ken possessed those of ordinary skills, can also under the prerequisite that does not break away from aim of the present invention, make various variations.
Claims (3)
1. analogy method after the survey of power transformer interior fault based on a coupling inductance port identity identification, it is characterized in that: when the transmission system containing transformer breaks down, in the short time window, survey respectively the voltage of transformer primary side leading-out terminal and secondary side leading-out terminal
u 1 , u 2and electric current
i 1 , i 2, according to the electromagnetic coupled relation of transformer, the voltage of analog computation secondary side leading-out terminal
, then by the analog voltage of secondary side leading-out terminal
with actual measurement voltage
u 2waveform compare, calculate the coefficient correlation of the two waveform
r, according to the similarity degree of both waveforms, be coefficient correlation
rthe size identification transformer whether internal fault occurs.
2. analogy method after the survey that the power transformer interior fault based on the coupling inductance port identity according to claim 1 is identified, it is characterized in that: the concrete steps of this method are as follows:
(1) when the transmission system containing transformer breaks down, in the short time window, survey respectively the voltage of transformer primary side leading-out terminal and secondary side leading-out terminal
u 1 , u 2and electric current
i 1 , i 2, then press the voltage of following formula analog computation Circuit Fault on Secondary Transformer leading-out terminal
:
In formula,
l 11,
l 22be respectively once and the secondary side winding self-induction,
,
i mi for exciting current, ω is angular frequency;
(2) be calculated as follows the analog voltage of Circuit Fault on Secondary Transformer leading-out terminal
with actual measurement voltage
u 2the coefficient correlation of waveform
r:
In formula, k=1,2,3...... N, N is the sampled data length in short time-window;
(3) according to the coefficient correlation calculated
r, whether the identification transformer internal fault occurs;
When
r≤0 o'clock is the transformer troubles inside the sample space;
When
r>0 o'clock is the transformer external area error.
3. the transformer internal fault external fault based on the coupling inductance port identity according to claim 1 and 2 is simulated recognition methods after surveying, it is characterized in that: when described measuring transformer one secondary side outlet voltage, electric current, the length of short time window is 5ms, and sample frequency is 20kHz.
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Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN105203876A (en) * | 2015-09-15 | 2015-12-30 | 云南电网有限责任公司电力科学研究院 | Transformer on-line monitoring state assessment method utilizing support vector machine and correlation analysis |
| CN116953413A (en) * | 2023-08-28 | 2023-10-27 | 建能电气股份有限公司 | Fault diagnosis system based on components and parts in cubical switchboard |
-
2013
- 2013-05-30 CN CN201310208840.2A patent/CN103457241B/en active Active
Non-Patent Citations (3)
| Title |
|---|
| 李爱民: "《华南理工大学博士学位论文》", 1 June 2010 * |
| 束洪春等: "利用电压相关性的800kv直流输电线路区内外故障判断方法", 《中国电机工程学报》 * |
| 董鑫: "《华北电力大学工学硕士学位论文》", 31 March 2008 * |
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN105203876A (en) * | 2015-09-15 | 2015-12-30 | 云南电网有限责任公司电力科学研究院 | Transformer on-line monitoring state assessment method utilizing support vector machine and correlation analysis |
| CN105203876B (en) * | 2015-09-15 | 2018-04-24 | 云南电网有限责任公司电力科学研究院 | It is a kind of to utilize support vector machines and the transformer online monitoring state evaluating method of correlation analysis |
| CN116953413A (en) * | 2023-08-28 | 2023-10-27 | 建能电气股份有限公司 | Fault diagnosis system based on components and parts in cubical switchboard |
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