CN204330917U - A kind of substation transformer incipient fault prior-warning device - Google Patents

Abstract

The utility model discloses a kind of substation transformer incipient fault prior-warning device, comprise current transformer, voltage transformer (VT), Intelligent Transformer Terminal Unit and background management system, be exclusively used in the on-line measurement of substation transformer current/voltage and data processing, draw the short-circuit impedance calculated value of reflection substation transformer winding deformation fault, the open circuit loss calculated value of reflection distribution transformer cores fault, again described calculated value and substation transformer factory-said value are compared, the running status of assessment substation transformer, Timeliness coverage incipient fault also carries out fault pre-alarming device, utilize this device, the safe operation of distribution transformer equipment can be guaranteed.

Description

A kind of substation transformer incipient fault prior-warning device

Technical field

The utility model relates to a kind of substation transformer incipient fault prior-warning device, data processing is carried out to measuring the electric current, voltage and the oil level signal that obtain in substation transformer operational process specifically by mutual inductor and intelligent monitoring terminal, draw short circuit in winding impedance and open circuit loss calculated value, and compare with factory-said value, determine whether the method and apparatus of distant early warning, belong to the intelligent running technology field of power distribution network.

Background technology

Substation transformer is the terminal core equipment be in electric power networks, it is directly in the face of electric power terminal user the most widely, quantity at most, position distribution very extensively, install and running environment very complicated, the whether normal power supply reliability that directly decide electric system of substation transformer running status.Because existing substation transformer exists problems in operational management, such as seasonality, period rate of load condensate difference are comparatively large, and when rate of load condensate is higher, transformer is in running overload state, has a strong impact on the operation life of substation transformer; On the other hand, the substation transformer of these One's name is legions is in safe operation process, also be the visual plant that maintenance management personnel need to pay close attention to most, but due to geographic position and environment, mounting condition etc. different, maintainer's quantity, skills involved in the labour and workload etc. are had higher requirement, difficulty is more, and therefore in fact most substation transformer is almost the state being in no supervision after putting into operation.According to statistics, the unplanned power failure that China causes because of substation transformer fault every year accounts for 70 ~ 80% of power distribution network power outage, and for overhauling, the scheduled outage of prerun only accounts for ~ 20%.Therefore be badly in need of adopting intelligent running technology to substation transformer, grasp the ruuning situation of substation transformer in time, its incipient fault is monitored and early warning, run department to electrical production and rational maintenance decision is provided, reduce unplanned power failure, ensure power supply safety, improve power supply reliability.

The intellectuality of the large-scale power transformer in the power hub networks such as transformer station runs is used widely, comprise the running status amount utilizing various on-line monitoring sensor to detect transformer in real time, thus the real-time running state of power transformer is assessed, Timeliness coverage incipient fault also carries out fault pre-alarming, for the stable operation of electric system and repair based on condition of component have played important effect.But for the intelligent running technology of substation transformer, be still in the development phase at present.

Chinese utility model patent " Intelligent monitoring system for distribution transformer platform area " (application number: CN201120278296.5) and the technical scheme disclosed in " a kind of Intelligent distribution transformer " (Authorization Notice No.: CN202839273) are by current/voltage sensor supervising device, realize distribution transformer platform area intelligent monitoring, comprise the real-time information monitorings such as load, the quality of power supply, abort situation, power failure, but do not propose to carry out early warning technology scheme to all kinds of incipient fault states of substation transformer.

Patent of invention " electric power transformer windings parameter on-line real-time identification device and method " (application number: 200810011051.9) can accomplish to detect Transformer Short Circuit Impedance real-time online, utilize least square to realize winding failure identification, the real-time analysis to transformer and fault pre-alarming can be realized; Patent of invention " Transformer Winding on-line monitoring system " (application number: monitoring function 201210590995.2) comprises the trend map etc. of the effective value of input and output voltage electric current, Wave data, reactance, also have based on database design, query statistic is flexibly provided; Patent of invention " On-line Measuring Method of transformer short-circuit loss and open circuit loss and system " (application number: be 201110273416.7) certain numerical operation is carried out to the voltage collected, current signal and constant pressure source signal and utilizes linear fit to realize the on-line measurement of short-circuit resistance; Patent of invention " a kind of transformer state information intelligent supervisory system and method " (application number: 201310493764.4) the various Signal transmissions of transformer to processor is carried out analyzing, processing, processor, based on the Method of Fault Diagnosis in Transformer preset, carries out fault diagnosis and risk assessment and the alarm when fault occurs to the operation conditions of transformer; Periodical " Electric Power Automation Equipment " (the 3rd phase in 2010, Fan Jingmin etc.) " the Winding in Power Transformer status real time monitor algorithm " delivered propose and utilize transformer primary, the voltage on secondary limit, current signal to carry out on-line identification to the short-circuit impedance of transformer, application wavelet transformation and Fourier transformation method, obtain equivalent short circuit impedance under load state, and propose when short-circuit impedance changing value reaches certain proportion, there will be winding deformation or shorted-turn fault.Disclosed in above patent or document, weak point is: can not carry out winding and fault pre-alarming unshakable in one's determination, or winding failure computing method are more loaded down with trivial details simultaneously, or the method set forth is simple, and in fact operability is not strong.

Increase along with for operating substation transformer on-line monitoring importance raising in enormous quantities, advanced fault pre-alarming demand; existing routine monitoring or guard method (as thermometric, oil level monitoring, over-current over-voltage protection etc.) is only adopted obviously to be difficult to reach demand; on the other hand, the monitoring protection method indiscriminately imitating hinge large-scale power transformer is unsuitable for again the many and substation transformer that separate unit relative capacity is less of quantity.Therefore, use for reference high-power transformer monitoring and protective device and method, creationary employing sensor cheap and easy to get, in conjunction with simple algorithm, realizing substation transformer winding and fault early warning method unshakable in one's determination and device becomes required.

Summary of the invention

The purpose of this utility model is the problem proposed for background technology, a kind of substation transformer incipient fault prior-warning device is disclosed, be exclusively used in the on-line measurement of substation transformer current/voltage and data processing, draw the short-circuit impedance calculated value of reflection substation transformer winding deformation fault, the open circuit loss calculated value of reflection distribution transformer cores fault, again described calculated value and substation transformer factory-said value are compared, the running status of assessment substation transformer, Timeliness coverage incipient fault also carries out fault pre-alarming device, utilize this device, the safe operation of distribution transformer equipment can be guaranteed.

The technical solution of the utility model is: a kind of substation transformer incipient fault prior-warning device, comprises current transformer, voltage transformer (VT), Intelligent Transformer Terminal Unit and background management system; Described current transformer is six high and low pressure side phase current sensing mutual inductors; Described voltage transformer (VT) is three measurement windings detecting substation transformer high-pressure side phase voltage, increase on substation transformer high pressure winding; It is characterized in that:

Described Intelligent Transformer Terminal Unit comprises data acquisition unit, data transmission unit, CPU (central processing unit) and fault alarm unit;

Described data acquisition unit is synchronous Real-time Collection substation transformer high and low pressure side phase current and phase voltage momentary signal value cell;

Described CPU (central processing unit) be according to substation transformer high and low pressure side phase current and phase voltage instantaneous, calculate substation transformer short-circuit reactance rate of change and open circuit loss rate of change by set algorithm; When short-circuit reactance rate of change or open circuit loss rate of change are higher than setting value, then judge that substation transformer winding exists distortion latent fault or iron core exists fault, and provide early warning signal by fault alarm unit;

The early warning signal that described fault alarm unit exports by described data transmission unit by wireless transmission to background management system.

The CPU (central processing unit) of a kind of substation transformer of the utility model incipient fault prior-warning device calculate the algorithm of substation transformer short-circuit reactance rate of change and open circuit loss rate of change and step as follows:

Step S1: setting substation transformer three-phase high and low pressure side current instantaneous value is respectively: i _1a, i _1b, i _1cand i _1a, i _1b, i _1c; Instantaneous voltage is respectively: u _1a, u _1b, u _1cand u _2a, u _2b, u _2c; Described current instantaneous value and instantaneous voltage are obtained by intelligent monitoring terminal synchronized sampling;

Step S2: utilize following formula to ask for A phase high and low pressure side current effective value I respectively _1awith voltage effective value U _1a:

$I_{1a}=\sqrt{\frac{1}{n}\underset{m=1}{\overset{n}{\mathrm{\Σ}}}{i}_{1a}\left(m\right)}---\left(1\right)$

$U_{1a}=\sqrt{\frac{1}{n}\underset{m=1}{\overset{n}{\mathrm{\Σ}}}{u}_{1a}\left(m\right)}---\left(2\right)$

In above formula, n is the sampling number in a power frequency period, i _1am () is the instantaneous value of A phase high-tension current at sampled point m place, u _1am () is the instantaneous value of A phase high tension voltage at sampled point m place;

Identical formula is utilized to obtain the effective value I of high-pressure side B phase current _1b, the effective value I of high-pressure side C phase current _1c, the effective value I of low-pressure side A phase current _2a, the effective value I of low-pressure side B phase current _2b, the effective value I of low-pressure side C phase current _2c; The effective value U of high-pressure side A phase voltage _1a, the effective value U of high-pressure side B phase voltage _1b, the effective value U of high-pressure side C phase voltage _1c, the effective value U of low-pressure side A phase voltage _2a, the effective value U of low-pressure side B phase voltage _2b, the effective value U of low-pressure side C phase voltage _2c;

Step S3: Fourier transform is carried out to the instantaneous value of the substation transformer high-pressure side A phase current obtained in step S1, obtains the initial phase φ of high-pressure side A phase current _i1a; In like manner can obtain the initial phase φ of high-pressure side B phase current _i1b, the initial phase φ of high-pressure side C phase current _i1c, the initial phase φ of low-pressure side A phase current _i2a, the initial phase φ of low-pressure side B phase current _i2b, the initial phase φ of low-pressure side C phase current _i2c; The initial phase φ of high-pressure side A phase voltage _u1a, the initial phase φ of high-pressure side B phase voltage _u1b, the initial phase φ of high-pressure side C phase voltage _u1c, the initial phase φ of low-pressure side A phase voltage _u2a, the initial phase φ of low-pressure side B phase voltage _u2b, the initial phase φ of low-pressure side C phase voltage _u2c;

Step S4: the phasor value obtaining substation transformer high and low pressure side current signal according to the result of step S1 and step S2 calculating, the wherein phasor value of high-pressure side A phase current signal in like manner can obtain the phasor value of high-pressure side B phase current signal the phasor value of high-pressure side C phase current signal the phasor value of high-pressure side A phase voltage signal the phasor value of high-pressure side B phase voltage signal the phasor value of high-pressure side C phase voltage signal the phasor value of low-pressure side A phase current signal the phasor value of low-pressure side B phase current signal the phasor value of low-pressure side C phase current signal the phasor value of low-pressure side A phase voltage signal the phasor value of low-pressure side B phase voltage signal the phasor value of low-pressure side C phase voltage signal

Step S5: calculate for convenience, converts high-pressure side by low-pressure side A phase current signal and voltage signal, and convert formula is as follows:

${\stackrel{\·}{I}}_{12a}=\frac{1}{k}{\stackrel{\·}{I}}_{2a}---\left(3\right)$

${\stackrel{\·}{U}}_{12a}=k{\stackrel{\·}{U}}_{2a}---\left(4\right)$

In like manner low-pressure side B phase current signal and voltage signal being converted to high-pressure side is with low-pressure side C phase current signal and voltage signal are converted to high-pressure side is with

Step S6: with reference to known single transformer equivalent circuit diagram, asks for substation transformer A equal value parameter according to following formula:

${\stackrel{\·}{U}}_{1a}-{\stackrel{\·}{U}}_{12a}=Z_{1a}\×{\stackrel{\·}{I}}_{1a}+Z_{12a}\×{\stackrel{\·}{I}}_{12a}---\left(5\right)$

Wherein Z _1a=R _1a+ jX _1afor the equivalent impedance of high-pressure side A phase winding, R _1aand X _1asubstitutional resistance and the equivalent reactance of high-pressure side A phase winding respectively, Z _12afor the equivalent impedance after the conversion of low-pressure side A phase winding, Z _12a=R _12a+ jX _12a, R _12aand X _12asubstitutional resistance and the equivalent reactance of the conversion of low-pressure side A phase winding respectively;

Then substation transformer A phase short-circuit impedance Z _ka=R _ka+ jX _ka, wherein R _kaand X _kabe respectively short-circuit resistance and the short-circuit reactance of substation transformer A phase, R _ka=R _1a+ R _12a, X _ka=X _1a+ X _12a;

In like manner solve substation transformer B phase short-circuit impedance Z _kb=R _kb+ jX _kbwith substation transformer C phase short-circuit impedance Z _kc=R _kc+ jX _kc, wherein R _kband R _kcbe respectively the short-circuit resistance of substation transformer B phase and C phase winding, X _kband X _kcbe respectively the short-circuit reactance of B phase and C phase winding;

Step S7: the short-circuit reactance X obtaining substation transformer according to following formula _k:

$X_k=\frac{X_{\mathrm{ka}}+X_{\mathrm{kb}}+X_{\mathrm{kc}}}{3}---\left(6\right)$

Step S8: the input active-power P solving substation transformer A phase according to following formula _a1with the active power of output P of A phase _a2:

$P_{a1}=\frac{1}{n}\underset{m=1}{\overset{n}{\mathrm{\Σ}}}{u}_{1a}\left(m\right)i_{1a}\left(m\right)---\left(7\right)$

$P_{a2}=\frac{1}{n}\underset{m=1}{\overset{n}{\mathrm{\Σ}}}{u}_{2a}\left(m\right)i_{2a}\left(m\right)---\left(8\right)$

In like manner can ask the input active-power P of substation transformer B phase _b1, the input active-power P of C phase _c1, the active power of output P of B phase _b2, the active power of output P of C phase _c2; The power input P that then substation transformer is total ₁=P _a1+ P _b1+ P _c1, total output power P ₂=P _a2+ P _b2+ P _c2, the active loss P that substation transformer is total _{total losses}=P ₁-P ₂;

Step S9: ignore stray loss when substation transformer runs, then loss when substation transformer runs is made up of iron loss and copper loss, utilizes formula: $P_{\mathrm{cu}-a}=I_{1a}^2\×R_{1a}+I_{12a}^2\×R_{12a}---\left(9\right)$

Solve the copper loss P of substation transformer A phase _cu-a;

In like manner obtain the copper loss P of B phase _cu-bwith the copper loss P of C phase _cu-c, then total copper loss P when substation transformer runs _cu:

P _cu＝P _cu-a+P _cu-b+P _cu-c⑽

Step S10: solve open circuit loss P when substation transformer runs according to following formula ₀:

P ₀=P _{total losses}-P _cu(11)

Step S11: calculate short-circuit reactance rate of change Δ X% according to following formula:

$\mathrm{\ΔX}\%=\left|\frac{X_k-X_b}{X_b}\right|\×100\%---\left(12\right)$

X in formula _bfor the reactance of substation transformer nominal short-circuit;

Step S12: calculate open circuit loss rate of change Δ P according to following formula ₀%:

$\mathrm{\Δ}{P}_0\%=\left|\frac{P_0-P_{0N}}{P_{0N}}\right|\×100\%---\left(13\right)$

P in formula _oNfor the loss of substation transformer rated no-load.

When short-circuit impedance rate of change >=10%; namely judge that substation transformer winding produces distortion latent fault; when open circuit loss rate of change >=15%; then judge that distribution transformer cores produces fault; now intelligent monitoring terminal sends alerting signal, warning message is uploaded to background management system by wireless transmission method simultaneously, provides staff to check scene; process, thus reach the object of effective protection substation transformer.

The utility model can realize carrying out Treatment Analysis to the data of substation transformer on-line monitoring, and carries out failure prediction and warning according to analysis result, effectively can reduce the probability that substation transformer accident occurs.

Accompanying drawing explanation

Accompanying drawing 1 is substation transformer latent fault prior-warning device structural representation;

Accompanying drawing 2 is single transformer equivalent circuit diagrams;

Accompanying drawing 3 is substation transformer latent fault prior-warning device CPU (central processing unit) algorithm flow charts.

Embodiment

Below in conjunction with accompanying drawing, the utility model embodiment is described further:

Substation transformer incipient fault prior-warning device as shown in Figure 1, comprises current transformer, voltage transformer (VT), Intelligent Transformer Terminal Unit and background management system; Described current transformer has six, detects high and low pressure side phase current values respectively; Described voltage transformer (VT) is three measurement windings increased on substation transformer high pressure winding.

In Fig. 1, Intelligent Transformer Terminal Unit comprises data acquisition unit, data transmission unit, CPU (central processing unit) and fault alarm unit; Wherein data acquisition unit is synchronous Real-time Collection substation transformer high and low pressure side phase current and phase voltage momentary signal value cell; CPU (central processing unit) be according to substation transformer high and low pressure side phase current and phase voltage instantaneous, calculate substation transformer short-circuit reactance rate of change and open circuit loss rate of change by set algorithm; When short-circuit reactance rate of change or open circuit loss rate of change are higher than setting value, then judge that substation transformer winding exists distortion latent fault or iron core exists fault, and provide early warning signal by fault alarm unit.

The early warning signal that described fault alarm unit exports by data transmission unit by wireless transmission to background management system.

In the utility model embodiment, current transformer, voltage transformer (VT) output signal is all lead to Intelligent Transformer Terminal Unit by the isolation waterproof general aviation socket on substation transformer top.

In actual applications, fault early warning method comprises the steps: the utility model substation transformer incipient fault prior-warning device

1. a current transformer is respectively installed on the high and low pressure side three-phase extension line of substation transformer in order to measure high and low pressure side phase current signal; On the winding of three-phase high-voltage side, increase and measure winding for gathering high-pressure side phase voltage signal; Three-phase low-voltage side extension line directly gathers low pressure phase voltage signal.

2. synchronized sampling step ①Zhong Ge road electric current, voltage signal, and collected signal is sent to Intelligent Transformer Terminal Unit.

3. described intelligent monitoring terminal carries out data processing to the electric current received, voltage signal, draws the short-circuit impedance calculated value of reflection substation transformer winding deformation fault and the open circuit loss calculated value of reflection distribution transformer cores fault.

4. short-circuit impedance calculated value and open circuit loss calculated value and substation transformer factory-said value are compared, calculate short-circuit impedance rate of change and open circuit loss rate of change, judge respectively:

When described short-circuit impedance rate of change is greater than setting threshold value, then judge that substation transformer winding exists distortion latent fault; Otherwise then substation transformer winding normal operation; In the present embodiment, short-circuit impedance rate of change setting threshold value is 10%.When described open circuit loss rate of change is greater than setting threshold value, then judge that distribution transformer cores exists fault, need confirm fault type further, on the contrary then substation transformer winding normal operation; In the present embodiment, open circuit loss rate of change setting threshold value is 15%.

If when judging that substation transformer winding existence distortion latent fault or distribution transformer cores exist fault, Intelligent Transformer Terminal Unit sends alerting signal.

5. alerting signal is uploaded to background management system by wireless transmission method, provides staff to check scene, process.

Above-mentioned steps 3. in, intelligent monitoring terminal carries out data processing to receiving current and voltage signals, and calculates short-circuit impedance and short-circuit impedance rate of change, open circuit loss and open circuit loss rate of change as follows:

Step S1: setting substation transformer three-phase high and low pressure side current instantaneous value is respectively: i _1a, i _1b, i _1cand i _1a, i _1b, i _1c; Instantaneous voltage is respectively: u _1a, u _1b, u _1cand u _2a, u _2b, u _2c; Described current instantaneous value and instantaneous voltage are obtained by intelligent monitoring terminal synchronized sampling.

Step S2: utilize following formula to ask for A phase high and low pressure side current effective value I respectively _1awith voltage effective value U _1a:

$I_{1a}=\sqrt{\frac{1}{n}\underset{m=1}{\overset{n}{\mathrm{\Σ}}}{i}_{1a}\left(m\right)}---\left(1\right)$

$U_{1a}=\sqrt{\frac{1}{n}\underset{m=1}{\overset{n}{\mathrm{\Σ}}}{u}_{1a}\left(m\right)}---\left(2\right)$

In above formula, n is the sampling number in a power frequency period, i _1am () is the instantaneous value of A phase high-tension current at sampled point m place, u _1am () is the instantaneous value of A phase high tension voltage at sampled point m place.

Identical formula is utilized to obtain the effective value I of high-pressure side B phase current _1b, the effective value I of high-pressure side C phase current _1c, the effective value I of low-pressure side A phase current _2a, the effective value I of low-pressure side B phase current _2b, the effective value I of low-pressure side C phase current _2c; The effective value U of high-pressure side A phase voltage _1a, the effective value U of high-pressure side B phase voltage _1b, the effective value U of high-pressure side C phase voltage _1c, the effective value U of low-pressure side A phase voltage _2a, the effective value U of low-pressure side B phase voltage _2b, the effective value U of low-pressure side C phase voltage _2c.

Step S3: Fourier transform is carried out to the instantaneous value of the substation transformer high-pressure side A phase current obtained in step one, obtains the initial phase φ of high-pressure side A phase current _i1a; In like manner can obtain the initial phase φ of high-pressure side B phase current _i1b, the initial phase φ of high-pressure side C phase current _i1c, the initial phase φ of low-pressure side A phase current _i2a, the initial phase φ of low-pressure side B phase current _i2b, the initial phase φ of low-pressure side C phase current _i2c; The initial phase φ of high-pressure side A phase voltage _u1a, the initial phase φ of high-pressure side B phase voltage _u1b, the initial phase φ of high-pressure side C phase voltage _u1c, the initial phase φ of low-pressure side A phase voltage _u2a, the initial phase φ of low-pressure side B phase voltage _u2b, the initial phase φ of low-pressure side C phase voltage _u2c.

Step S4: the result calculated according to step one and step 2 obtains the phasor value of substation transformer high and low pressure side current signal, the wherein phasor value of high-pressure side A phase current signal in like manner can obtain the phasor value of high-pressure side B phase current signal the phasor value of high-pressure side C phase current signal the phasor value of high-pressure side A phase voltage signal the phasor value of high-pressure side B phase voltage signal the phasor value of high-pressure side C phase voltage signal the phasor value of low-pressure side A phase current signal the phasor value of low-pressure side B phase current signal the phasor value of low-pressure side C phase current signal the phasor value of low-pressure side A phase voltage signal the phasor value of low-pressure side B phase voltage signal the phasor value of low-pressure side C phase voltage signal

Step S5: calculate for convenience, converts high-pressure side by low-pressure side A phase current signal and voltage signal, and convert formula is as follows:

${\stackrel{\·}{I}}_{12a}=\frac{1}{k}{\stackrel{\·}{I}}_{2a}---\left(3\right)$

${\stackrel{\·}{U}}_{12a}=k{\stackrel{\·}{U}}_{2a}---\left(4\right)$

In like manner low-pressure side B phase current signal and voltage signal being converted to high-pressure side is with low-pressure side C phase current signal and voltage signal are converted to high-pressure side is with

Step S6: with reference to the single transformer equivalent circuit diagram shown in accompanying drawing 2, ask for substation transformer A equal value parameter according to following formula:

${\stackrel{\·}{U}}_{1a}-{\stackrel{\·}{U}}_{12a}=Z_{1a}\×{\stackrel{\·}{I}}_{1a}+Z_{12a}\×{\stackrel{\·}{I}}_{12a}---\left(5\right)$

Wherein Z _1a=R _1a+ jX _1afor the equivalent impedance of high-pressure side A phase winding, R _1aand X _1asubstitutional resistance and the equivalent reactance of high-pressure side A phase winding respectively, Z _12a=R _12a+ jX _12afor the equivalent impedance after the conversion of low-pressure side A phase winding, R _12aand X _12asubstitutional resistance and the equivalent reactance of the conversion of low-pressure side A phase winding respectively; Substation transformer A phase short-circuit impedance Z _ka=R _ka+ jX _ka, wherein R _ka=R _1a+ R _12aand X _ka=X _1a+ X _12abe respectively short-circuit resistance and the short-circuit reactance of substation transformer A phase.

In like manner solve substation transformer B phase short-circuit impedance Z _kb=R _kb+ jX _kbwith substation transformer C phase short-circuit impedance Z _kc=R _kc+ jX _kc, wherein R _kb, X _kb, R _kcand X _kcbe respectively short-circuit resistance, the short-circuit reactance of the short-circuit resistance of substation transformer B phase winding, short-circuit reactance and C phase winding.

Step S7: the short-circuit reactance X obtaining substation transformer according to following formula _k:

$X_k=\frac{X_{\mathrm{ka}}+X_{\mathrm{kb}}+X_{\mathrm{kc}}}{3}---\left(6\right)$

Step S8: the input active-power P solving substation transformer A phase according to following formula _a1with the active power of output P of A phase _a2:

$P_{a1}=\frac{1}{n}\underset{m=1}{\overset{n}{\mathrm{\Σ}}}{u}_{1a}\left(m\right)i_{1a}\left(m\right)---\left(7\right)$

$P_{a2}=\frac{1}{n}\underset{m=1}{\overset{n}{\mathrm{\Σ}}}{u}_{2a}\left(m\right)i_{2a}\left(m\right)---\left(8\right)$

In like manner can ask the input active-power P of substation transformer B phase _b1, the input active-power P of C phase _c1, the active power of output P of B phase _b2, the active power of output P of C phase _c2; The power input P that then substation transformer is total ₁=P _a1+ P _b1+ P _c1, total output power P ₂=P _a2+ P _b2+ P _c2, the active loss P that substation transformer is total _{total losses}=P ₁-P ₂.

Step S9: ignore stray loss when substation transformer runs, then loss when substation transformer runs is made up of iron loss and copper loss, utilizes formula: $P_{\mathrm{cu}-a}=I_{1a}^2\×R_{1a}+I_{12a}^2\×R_{12a}---\left(9\right)$

Solve the copper loss P of substation transformer A phase _cu-a;

In like manner obtain the copper loss P of B phase _cu-bwith the copper loss P of C phase _cu-c, then total copper loss P when substation transformer runs _cu:

P _cu＝P _cu-a+P _cu-b+P _cu-c⑽

Step S10: solve open circuit loss P when substation transformer runs according to following formula ₀:

P ₀=P _{total losses}-P _cu(11)

Step S11: calculate short-circuit reactance rate of change Δ X% according to following formula:

$\mathrm{\ΔX}\%=\left|\frac{X_k-X_b}{X_b}\right|\×100\%---\left(12\right)$

X in formula _bfor the reactance of substation transformer nominal short-circuit.

Step S12: calculate open circuit loss rate of change Δ P according to following formula ₀%:

$\mathrm{\Δ}{P}_0\%=\left|\frac{P_0-P_{0N}}{P_{0N}}\right|\×100\%---\left(13\right)$

P in formula _oNfor the loss of substation transformer rated no-load.

Because the utility model adopts electric current, voltage sensor cheap and easy to get, realize high-low pressure current/voltage instantaneous value to measure and data acquisition, in conjunction with Intelligent Transformer Terminal Unit and background management system, by simple algorithm, draw the short-circuit impedance rate of change calculated value of reflection substation transformer winding deformation fault and the open circuit loss rate of change calculated value of reflection distribution transformer cores fault simultaneously, and differentiate in substation transformer operational process, whether winding and iron core exist incipient fault.

Claims (1)

1. a substation transformer incipient fault prior-warning device, comprises current transformer, voltage transformer (VT), Intelligent Transformer Terminal Unit and background management system; Described current transformer is six high and low pressure side phase current sensing mutual inductors; Described voltage transformer (VT) is three measurement windings detecting substation transformer high-pressure side phase voltage, increase on substation transformer high pressure winding; It is characterized in that:

Described Intelligent Transformer Terminal Unit comprises data acquisition unit, data transmission unit, CPU (central processing unit) and fault alarm unit;

Described data acquisition unit is synchronous Real-time Collection substation transformer high and low pressure side phase current and phase voltage momentary signal value cell;

Described CPU (central processing unit) be according to substation transformer high and low pressure side phase current and phase voltage instantaneous, calculate substation transformer short-circuit reactance rate of change and open circuit loss rate of change by set algorithm; When short-circuit reactance rate of change or open circuit loss rate of change are higher than setting value, then judge that substation transformer winding exists distortion latent fault or iron core exists fault, and provide early warning signal by fault alarm unit;

The early warning signal that described fault alarm unit exports by described data transmission unit by wireless transmission to background management system.