CN104330691A - Online monitoring system for power transformer winding vibration signals - Google Patents

Abstract

The invention provides an online monitoring system for power transformer winding vibration signals. The online monitoring system comprises a signal amplifying circuit, an A/D (analog-digital) conversion circuit, a level conversion circuit and a signal processing module which are sequentially connected with a vibration acquisition module, the signal processing module and a man-machine interaction unit are connected with each other and then respectively connected with a PC (personal computer) through a communication module, the signal processing module computes vibration energy of different frequency bands of the power transformer winding vibration signals, the vibration energy of the frequency bands is compared with an energy threshold value by the PC, and a failure winding phase in a power transformer is judged. Compared with the prior art, the online monitoring system for the power transformer winding vibration signals can online monitor the vibration signals when the transformer is short-circuited in real time, acquired data are synchronously uploaded to the PC, a diagnosis result is displayed through a display module, and the online monitoring system gives the alarm in real time to explain the running state of a transformer.

Description

A kind of Winding in Power Transformer vibration signal on-line monitoring system

Technical field

The present invention relates to a kind of vibration signal monitoring system, be specifically related to a kind of Winding in Power Transformer vibration signal on-line monitoring system.

Background technology

Power transformer is as one of most important hinge of electric system, its safe operation is directly connected to the safety and reliability of generating and electric power system, is therefore the important process ensureing that electric power system is normally run to the fault detect of transformer, maintenance and maintenance.

Have for the main method detecting deformation of transformer winding at present: short-circuit test method, Low Voltage Impulse Method, frequency response method etc.These methods all need transformer out of service, do not consider the actual conditions of transformer, may occur too much maintenance and unnecessary shutdown, again can not Timeliness coverage Transformer Winding defect.When Transformer Winding generation mechanically deform, the Magnetic fluxleakage distribution at this place certainly will be caused to change, the basket vibration that load current and leakage field acting in conjunction produce also changes, and vibration signal is delivered to tank surface by oily medium, therefore also changes at the basket vibration signal of tank surface.Vibration analysis method does not have electrical equipment to be connected with whole electric system, normally runs have no effect to electric system, therefore the method safely, reliably can reach the object of on-line monitoring.

Existing transformer vibration monitor system hardware circuit is complicated, and poor anti jamming capability.Data processing is main mainly with traditional analysis, and as amplitude domain analytic approach, Fast Fourier Transform (FFT) and correlation analysis etc., the vibrational energy under each frequency of display that can not be real-time over time.Therefore, need to provide a kind of Winding in Power Transformer vibration signal on-line monitoring system, can either Real-Time Monitoring time domain vibrational waveform, again can vibrational energy be over time under each frequency of Real-Time Monitoring.

Summary of the invention

In order to meet the needs of prior art, the invention provides a kind of Winding in Power Transformer vibration signal on-line monitoring system, described system involving vibrations acquisition module, described vibration acquisition module comprises the vibration transducer gathering Winding in Power Transformer vibration signal, and described system comprises the signal amplification circuit, A/D change-over circuit, level shifting circuit and the signal processing module that are connected successively with described vibration acquisition module;

Described signal processing module is connected with PC respectively by communication module after being connected with man-machine interaction unit; Described signal processing module calculates the vibrational energy of Winding in Power Transformer vibration signal different frequency range;

The described vibrational energy of each frequency range compares with energy threshold by described PC, judges the winding phase broken down in power transformer.

Preferably, described energy threshold comprises low frequency component threshold value and high fdrequency component threshold value; When vibrational energy in the primary band of Winding in Power Transformer vibration signal is less than described low frequency component threshold value, or when being greater than high fdrequency component threshold value, then the winding phase broken down in power transformer;

Described primary band is the power transformer frequency range that vibrational energy is concentrated when normally running, and described frequency range is 100 ~ 400Hz;

Preferably, described signal processing module comprises the DSP minimum system, SRAM and FLASH that are arranged on DSP core board; Described DSP minimum system comprises dsp chip, power supply, RAM, clock source and I/O interface;

Described DSP minimum system, discrete Fourier transformation is carried out to Winding in Power Transformer vibration signal, with shannon wavelet packet decomposition by transformer winding vibration signal decomposition in different frequency range, calculate the Energy-Entropy of each frequency range to obtain the vibrational energy of different frequency range, and result of calculation is sent to PC;

Preferably, the computing formula that described signal processing module shannon wavelet packet decomposition calculates the Energy-Entropy of each frequency range is:

$H_{\mathrm{jk}}=-\underset{i=1}{\overset{n}{\mathrm{\Σ}}}{\mathrm{\ϵ}}_{(j,k)}\left(i\right)\lg {\mathrm{\ϵ}}_{(j,k)}\left(i\right)---\left(1\right)$

Wherein, described H _jkfor a jth layer kth wavelet-packet energy entropy of vibration signal;

Described s _{f (j, k)}i-th value of i Fourier transform sequence that () is, n is the length of the original signal of vibration signal;

Preferably, described vibration acquisition module comprises constant current source module, voltage source is converted to the constant current source needed for described vibration transducer;

Preferably, described signal amplification circuit comprises the first amplifier and the second amplifier;

The in-phase input end of described first amplifier and described vibration acquisition model calling, a branch road of inverting input passes through resistance eutral grounding, another branch road is connected with its output terminal by resistance, and described output terminal is held with the IN+ of ADS8364 chip in described A/D change-over circuit and is connected;

The reverse input end of described second amplifier is connected with its output terminal, and in-phase input end is held with the REF of described ADS8364 chip and is connected; A branch road of described output terminal is connected by the in-phase input end of resistance with the first amplifier, and another branch road to be held with the IN-of described ADS8364 chip by circuit and is connected;

Preferably, described level shifting circuit comprises two 16 bidirectional bus converters, and the digital signal conversion of-5V ~ 5V exported by described A/D change-over circuit is the digital signal of 3.3V;

Described 16 bidirectional bus converters are 74LVC16245A chip;

Preferably, the input-output apparatus of described man-machine interaction unit comprises display module and voice alarm module; Dsp chip in described signal processing module carries out sequential by control I/O interface and described input-output apparatus and mates;

The command signal that described man-machine interaction unit issues according to described PC, shows the winding phase audio alert that break down in described power transformer.

Compared with immediate prior art, excellent effect of the present invention is:

1, in technical solution of the present invention, two-sided placement components and parts are adopted, the space of Appropriate application PCB; The components and parts that electric connecting relation is close are adopted to the mode of modular layout; And the crystal oscillator being easy to produce noise is placed on the input end of clock near CPU, reduces the power consumption of noise signal and components and parts, improve the service efficiency of element;

2, in technical solution of the present invention, the dsp chip in signal processing module adopts TMS320F28335 chip, can process vibration data fast, improve work efficiency; Signal processing module memory storage space is large, and work efficiency is high and have very high operational precision;

3, in technical solution of the present invention, A/D modular converter sampling precision is high, can change 6 road signals simultaneously; Adopt the ADS8364 conversion chip with Differential Input, this A/D modular converter can accept bipolar input signal, ensure that the normal acquisition of negative signal;

4, in technical solution of the present invention, adopt shannon wavelet packet decomposition, the energy under each frequency of calculating transformer vibration signal that can be real-time over time, further can analyze the Changing Pattern of transformer vibration signal;

5, Winding in Power Transformer vibration signal on-line monitoring system provided by the invention, under transformer impacts by Guangdong power system, when winding in transformer and iron core generation impact being affected by external fault, can accomplish vibration signal real time on-line monitoring during transformer short-circuit, and can by image data synchronized upload to PC, and shown by display module by diagnostic result, and running state of transformer can be described Realtime Alerts.

Accompanying drawing explanation

Below in conjunction with accompanying drawing, the present invention is further described.

Fig. 1: a kind of Winding in Power Transformer vibration signal on-line monitoring system structural representation in the embodiment of the present invention;

Fig. 2: a kind of Winding in Power Transformer vibration signal on-line monitoring system circuit theory diagrams in the embodiment of the present invention;

Fig. 3: man-machine interaction unit interface circuit figure in the embodiment of the present invention;

Fig. 4: communication module circuit diagram in the embodiment of the present invention;

Fig. 5: a kind of Winding in Power Transformer vibration signal on-line monitoring system monitoring schematic flow sheet in the embodiment of the present invention.

Embodiment

Be described below in detail embodiments of the invention, the example of described embodiment is shown in the drawings, and wherein same or similar label represents same or similar element or has element that is identical or similar functions from start to finish.Be exemplary below by the embodiment be described with reference to the drawings, be intended to for explaining the present invention, and can not limitation of the present invention be interpreted as.

Winding in Power Transformer vibration signal on-line monitoring system provided by the invention can solve the circuit complexity of traditional transformer vibration monitor system, poor anti jamming capability primary analyses method can not show the time dependent problem of each frequency energy, this system involving vibrations acquisition module, signal amplification circuit, A/D change-over circuit, level shifting circuit, signal processing module, man-machine interaction unit, communication module and PC as shown in Figure 1 in real time; Vibration acquisition module, signal amplification circuit, A/D change-over circuit, level shifting circuit are connected successively with signal processing module, and signal processing module is connected with PC respectively by communication module after being connected with man-machine interaction unit.

One, vibration acquisition module;

Involving vibrations sensor and constant current source module.

1, vibration transducer, gathers Winding in Power Transformer vibration signal.In the present embodiment, vibration transducer adopts piezoelectric acceleration transducer, and this sensor son's wife, on the surface of power transformer mailbox, converts vibration signal to electric signal and is sent to signal amplification circuit through concentric cable.

2, constant current source module, is converted to the constant current source needed for vibration transducer by the voltage source that vibration acquisition module provides.

Two, signal amplification circuit;

As shown in Figure 2, the first amplifier A1 and the second amplifier A2 is comprised.

The in-phase input end of the first amplifier A1 is by circuit R2 and vibration acquisition model calling, inverting input comprises two branch roads, article one, branch road is by resistance R1 ground connection, another branch road is connected with its output terminal by resistance R3, and this output terminal is held with the IN+ of ADS8364 chip in A/D change-over circuit and is connected;

Accessed the in-phase input end of the first amplifier A1 after the reverse input end of the second amplifier A2 is connected with its output terminal by resistance R6, the in-phase input end of the second amplifier A2 is held with the REF of ADS8364 chip and is connected; A branch road of the output terminal of the second amplifier A2 is connected with the in-phase input end of the first amplifier by resistance R6, and another branch road is held with the IN-of ADS8364 chip by resistance R7 and is connected.

In the present embodiment, resistance R1=4K Ω, R2=R4=R8=20K Ω, R5=R7=1.2K Ω K Ω, R3=2K Ω, R6=10K Ω, the output of signal amplification circuit is 0 ~ 5V.

Three, A/D change-over circuit;

Comprise ADS8364 chip.

ADS8364 chip has Differential Input, the signal amplification circuit of bipolarity input can be received, expand the acquisition range of A/D change-over circuit, therefore in the present embodiment, the output signal 0 ~ 5V of signal amplification circuit is expanded as-5V ~+5V by A/D change-over circuit, ensures the normal acquisition to negative signal.

Four, level shifting circuit;

Comprise two 16 bidirectional bus converters.

The digital signal conversion of-5V ~+5V that A/D change-over circuit exports is the digital signal of 3.3V by level shifting circuit, to communicate with in signal processing module.In the present embodiment, 16 bidirectional bus converters adopt 74LVC16245A chip, and can meet the I/O of the data-signal of 3 ~ 5V, the direction of conversion can be controlled by direction controlling pin DIR, completes level conversion.

Five, signal processing module;

Comprise the DSP minimum system, SRAM and FLASH that are arranged on DSP core board.

In the present embodiment, DSP minimum system comprises dsp chip, power supply, RAM, clock source and I/O interface.Dsp chip adopts TMS320F28335 chip, TMS320F28335 chip adds single-precision floating point arithmetic element FPU and High-Accuracy PWM, and Flash adds one times (256K × 16Bit), add DMA function simultaneously, can by the transformation result of A/D modular converter directly stored in the arbitrary storage space on DSP core board.In addition, TMS320F28335 chip also add CAN communication module, SCI interface and SPI interface.The dominant frequency of TMS320F28335 chip is up to 150MHz, there is exterior storage expansion interface simultaneously, house dog, three timers, 18 PWM export and 12 bit A/D converters of 16 passages, and it is compatible with fixed point C28x controller software, thus simplification software development, shorten the construction cycle, reduce cost of development, vibration data can be processed fast, improve work efficiency.

The storage space of signal processing module storer is large, can be used in the functions such as the collection of big data quantity, computing, transmission.TMS320F28335 chip functions pin is many, can be used in extended power transformer winding vibration signal on-line monitoring system; Its floating type operational advantage, makes it have powerful data-handling capacity, and has very high operational precision.

DSP minimum system, Winding in Power Transformer vibration signal is carried out to the discrete Fourier transformation of continuous signal, with shannon wavelet packet decomposition by transformer winding vibration signal decomposition in different frequency range, calculate the Energy-Entropy of each frequency range to obtain the vibrational energy of different frequency range, and result of calculation is sent to PC.

DSP minimum system with shannon wavelet packet decomposition by transformer winding vibration signal decomposition to 2 ⁿin individual different frequency range, calculate the Energy-Entropy of each frequency range to obtain the vibrational energy of different frequency range; The computing formula of Energy-Entropy is:

$H_{\mathrm{jk}}=-\underset{i=1}{\overset{n}{\mathrm{\Σ}}}{\mathrm{\ϵ}}_{(j,k)}\left(i\right)\lg {\mathrm{\ϵ}}_{(j,k)}\left(i\right)---\left(1\right)$

Wherein, H _jkfor a jth layer kth wavelet-packet energy entropy of vibration signal;

s _{f (j, k)}i-th value of i Fourier transform sequence that () is, n is the length of the original signal of vibration signal.

By 2 ⁿindividual wavelet-packet energy entropy composition Energy-Entropy vector T, then have it is normalized and obtains then vector T ' is normalization wavelet packet character vector:

$T^{\′}=[\frac{H_{n,0}}{H},\frac{H_{n,1}}{H},...,\frac{H_{n,2^{n-1}}}{H}]---\left(2\right)$

Six, man-machine interaction unit;

Man-machine interaction unit comprises input-output apparatus, mainly contains display module, voice alarm module and printer etc.; The command signal that man-machine interaction unit issues according to PC, the winding phase also audio alert broken down in display power transformer.

Because the dsp chip in signal processing module is high speed processor, the read-write cycle of the input-output apparatus of man-machine interaction unit is slower, therefore in order to solve the sequential matching problem of dsp chip and input-output apparatus, dsp chip carries out sequential by control I/O interface and input-output apparatus and mates, namely indirectly realize dsp chip by the interface routine called in dsp chip to mate with the sequential of slow devices, this mode can realize carrying out sequential between arbitrary sequence equipment at a slow speed without the need to any hardware and mate, as shown in Figure 3.

Seven, communication module;

As shown in Figure 4, in the present embodiment, communication module is RS-485 communication module, adopts balance to send and differential received, therefore has the ability suppressing common mode interference; Its bus transceiver has high sensitivity simultaneously, and can detect the voltage being low to moderate 200mV, signal transmission can be restored beyond km, realizes telecommunication.

Eight, PC;

PC Received signal strength processing module sends data, is compared by vibrational energy, judge the winding phase broken down in power transformer with energy threshold.

Energy threshold comprises low frequency component threshold value and high fdrequency component threshold value; When vibrational energy in the primary band of Winding in Power Transformer vibration signal is less than described low frequency component threshold value, or when being greater than high fdrequency component threshold value, then the winding phase broken down in power transformer; Primary band is the power transformer frequency range that vibrational energy is concentrated when normally running, and this frequency range is 100 ~ 400Hz.

PC display transformer winding vibration time-domain diagram, energygram etc., PC is to man-machine interaction unit transmission command simultaneously, shows fault phase by display module, and explanation running state of transformer of reporting to the police.

Nine, as shown in Figure 5, in the present embodiment, the course of work of monitoring system is:

1, arrange the sample frequency of vibration acquisition module, vibration transducer converts non-electrical signal to electric signal and is transferred to signal amplification circuit through coaxial wire, is amplified by signal, input saturation, is carrying out analog to digital conversion through A/D modular converter.

2, the digital signal of vibration signal is transferred to signal processing module through level shifting circuit and calculates, and uploads to PC by communication module, display transformer winding vibration time-domain signal and eigenwert Energy-Entropy.

3, when transformer normally runs, its basket vibration energy major part concentrates in 100-400Hz, and when transformer breaks down or there is incipient fault, radio-frequency component increases, and causes high-frequency energy ratio to increase, and primary band energy reduces.Using each band energy under normal operating condition as reference fingerprint vector, with the data real-time monitored herewith reference fingerprint amount make comparisons, when primary band energy is less than low frequency component threshold value or high fdrequency component energy higher than high fdrequency component threshold value, be diagnosed as transformer fault.PC to man-machine interaction unit transmission command signal, will show transformer winding fault phase by display module, audio alert simultaneously.

Ten, the installation safeguard procedures of the monitoring system of the present invention's proposition comprise:

Service condition due to monitoring system is usually very complicated, measured vibration signal is converted into the signal of 0-20mA or 0-5V usually, and logical long-distance hard-wire transfer is to PC, therefore can there is undesired signal, mainly comprise induction electromotive force and common mode interference.

1, induction electromotive force;

Induction electromotive force, when the environment of test vibration signal is in magnetic field environment, the athletic meeting of wire produces induction electromotive force.

According to the feature of transformer vibration signal, simultaneously in order to reliable, the accuracy of test vibration signal, vibration transducer is fixed on coaxial wire, prevents the loosening damage vibration transducer of vibration transducer joint.Coaxial wire is fixedly avoided the impact of induction electromotive force in test process simultaneously.

2, common mode interference;

Common mode interference, due to the potential difference (PD) that different potentials causes, the signal input part of monitoring system can induce common voltage over the ground by the mode of electrostatic coupling.

The signal input part of monitoring system adopts low-pass filter circuit filtering common mode interference current, and the common mode current on identical earth potential filtering cable is selected at coaxial wire two ends, and the interference that signal is subject to is little as much as possible.

Based on the embodiment in the application, those of ordinary skill in the art are not making the every other embodiment obtained under creative work prerequisite, all belong to the scope of the application's protection.

Claims (8)

1. a Winding in Power Transformer vibration signal on-line monitoring system, described system involving vibrations acquisition module, described vibration acquisition module comprises the vibration transducer gathering Winding in Power Transformer vibration signal, it is characterized in that, described system comprises the signal amplification circuit, A/D change-over circuit, level shifting circuit and the signal processing module that are connected successively with described vibration acquisition module;

Described signal processing module is connected with PC respectively by communication module after being connected with man-machine interaction unit; Described signal processing module calculates the vibrational energy of Winding in Power Transformer vibration signal different frequency range;

The described vibrational energy of each frequency range compares with energy threshold by described PC, judges the winding phase broken down in power transformer.

2. the system as claimed in claim 1, is characterized in that, described energy threshold comprises low frequency component threshold value and high fdrequency component threshold value; When vibrational energy in the primary band of Winding in Power Transformer vibration signal is less than described low frequency component threshold value, or when being greater than high fdrequency component threshold value, then the winding phase broken down in power transformer;

Described primary band is the power transformer frequency range that vibrational energy is concentrated when normally running, and described frequency range is 100 ~ 400Hz.

3. the system as claimed in claim 1, is characterized in that, described signal processing module comprises the DSP minimum system, SRAM and FLASH that are arranged on DSP core board; Described DSP minimum system comprises dsp chip, power supply, RAM, clock source and I/O interface;

Described DSP minimum system, discrete Fourier transformation is carried out to Winding in Power Transformer vibration signal, with shannon wavelet packet decomposition by transformer winding vibration signal decomposition in different frequency range, calculate the Energy-Entropy of each frequency range to obtain the vibrational energy of different frequency range, and result of calculation is sent to PC.

4. system as claimed in claim 3, it is characterized in that, the computing formula that described signal processing module shannon wavelet packet decomposition calculates the Energy-Entropy of each frequency range is:

$H_{\mathrm{jk}}=-\underset{i=1}{\overset{n}{\mathrm{\Σ}}}{\mathrm{\ϵ}}_{(j,k)}\left(i\right)\lg {\mathrm{\ϵ}}_{(j,k)}\left(i\right)---\left(1\right)$

Wherein, described H _jkfor a jth layer kth wavelet-packet energy entropy of vibration signal;

Described s _{f (j, k)}i-th value of i Fourier transform sequence that () is, n is the length of the original signal of vibration signal.

5. the system as claimed in claim 1, is characterized in that, described vibration acquisition module comprises constant current source module, voltage source is converted to the constant current source needed for described vibration transducer.

6. the system as claimed in claim 1, is characterized in that, described signal amplification circuit comprises the first amplifier and the second amplifier;

The in-phase input end of described first amplifier and described vibration acquisition model calling, a branch road of inverting input passes through resistance eutral grounding, another branch road is connected with its output terminal by resistance, and described output terminal is held with the IN+ of ADS8364 chip in described A/D change-over circuit and is connected;

The reverse input end of described second amplifier is connected with its output terminal, and in-phase input end is held with the REF of described ADS8364 chip and is connected; A branch road of described output terminal is connected by the in-phase input end of resistance with the first amplifier, and another branch road to be held with the IN-of described ADS8364 chip by circuit and is connected.

7. the system as claimed in claim 1, is characterized in that, described level shifting circuit comprises two 16 bidirectional bus converters, and the digital signal conversion of-5V ~ 5V exported by described A/D change-over circuit is the digital signal of 3.3V;

Described 16 bidirectional bus converters are 74LVC16245A chip.

8. the system as claimed in claim 1, is characterized in that, the input-output apparatus of described man-machine interaction unit comprises display module and voice alarm module; Dsp chip in described signal processing module carries out sequential by control I/O interface and described input-output apparatus and mates;

The command signal that described man-machine interaction unit issues according to described PC, shows the winding phase audio alert that break down in described power transformer.