CN201266232Y

CN201266232Y - AC test device for on-load tap-changer operating characteristic of transformer

Info

Publication number: CN201266232Y
Application number: CNU2008200303199U
Authority: CN
Inventors: 王登第
Original assignee: XI'AN TIANCHENG ELECTRICAL POWER INSTRUMENT AND EQUIPMENT CO Ltd
Current assignee: XI'AN TIANCHENG ELECTRICAL POWER INSTRUMENT AND EQUIPMENT CO Ltd
Priority date: 2008-09-18
Filing date: 2008-09-18
Publication date: 2009-07-01
Anticipated expiration: 2018-09-18

Abstract

The utility model relates to a device for testing the performance characteristic of an on-load tapping changing switch of a transformer by applying an AC supply, which belongs to a failure detecting device of power equipment and solves the problem that the accuracy is lower for DC detection. The device comprises a power supply, a signal sampler, a signal detecting and processing circuit connected with the output end of the sampler, and a display output unit. The device is characterized in that the power supply is a three-phase frequency modulation AC supply; the signal sampler is a voltage transformer and a current transformer; the signal detecting and processing circuit consists of a filter shaping circuit, a synchronized signal acquisition circuit, a data storage circuit and a digital processing circuit which are connected in sequence; the output end of the digital processing circuit is connected with the display output unit through a key control circuit; and the voltage transformer and the current transformer are connected with a tested transformer.

Description

AC test device for transformer on-load tap-changer operating characteristic

Technical field

The utility model belongs to the fault-locating unit of power equipment, specifically a kind of device of using AC electric source testing on-load tap changers of transformers acting characteristic.

Background technology

On-load tap changers of transformers is installed on the high pressure major loop of transformer, it is the major equipment of adjusting voltage, himself be again the parts of motion, therefore the characteristic of load ratio bridging switch is very important for the normal operation of transformer, all will carry out the test of on-load tap changers of transformers band winding acting characteristic usually after transformer assembling and on-the-spot the installation.The test of shunting switch band winding acting characteristic is according to the voltage in the on-load tap changers of transformers course of action of being gathered, current signal waveform and other data, the acting characteristic that provides on-load tap changers of transformers is described, and in view of the above the operation of on-load tap changers of transformers is provided evaluation, as the foundation of the examination and test of products, examination or repair and maintenance.

At present, the on-load tap changers of transformers Characteristics Detection all adopts DC test, all is to adopt the direct current detection mode as Chinese patent CN2279615 and the disclosed on-load tap changers of transformers comprehensive test apparatus of Chinese patent CN2304131.The applicant thinks: owing to be subjected between Transformer Winding inductance, end electric capacity, contact oil film, the contact influence such as switching time tool collision spring during on-the-spot test, DC test waveform and actual waveform have bigger difference, as vibration, vibration, spring cutout etc., the pressure regulation of transformer is actually and is under the communication environment in addition, this just makes very difficult to the differentiation of waveform, particularly to irregular DC test waveform, the tester can provide multiple possibility conclusion, therefore, existing DC test is relatively poor to the uniqueness of wave analysis, and accuracy is lower.

Summary of the invention

Problem to be solved in the utility model is: a kind of AC test device for transformer on-load tap-changer operating characteristic accurate, that precision is high that detects is provided.

The technical scheme that addresses the above problem is: the AC test device for transformer on-load tap-changer operating characteristic that is provided comprises power supply, signal sampler, input treatment circuit that is connected with the sampling thief output terminal and demonstration output unit, special feature of the present utility model is that said power supply is three-phase frequency modulation standard electric alternating current source, said signal sampler is the voltage transformer (VT) summation current transformer, said input treatment circuit is by the filtering shaping circuit that connects successively, the synchronous signal acquisition circuit, data storage circuitry and digital processing circuit are formed, the output terminal of digital processing circuit is connected with the demonstration output unit by core control circuit, and said voltage transformer (VT) summation current transformer is connected with tested transformer.During detection, pass to the test alternating current of standard for tested Transformer Winding by three-phase frequency modulation AC power, the voltage transformer (VT) summation current transformer is delivered to treatment circuit with the alternating voltage and the AC current waveform signal of the shunting switch change action process of collection, delivers to the demonstration output unit after treatment and stores behind display analysis on the screen or print.Can provide evaluation to the acting characteristic of on-load tap changers of transformers in view of the above.

Compare with existing direct current test apparatus, more near the actual motion environment of equipment under test, resulting test result also has cogency to alternating-current measurement state of the present utility model more.For example: in the DC test, the switching time tool collides influences such as spring between Transformer Winding inductance, end electric capacity, contact oil film, the contact owing to being subjected to, the variation of DC current in the test, to produce bigger back-emf, and domestic engineering circle is misread the jump that is interpreted as in the switch handoff procedure and interrupted for many years always; Even but near the waveform the alternating-current measurement current zero-crossing point also is slick and sly continuous, illustrate not exist in the normal switch handoff procedure and jump that practice has also proved this point with interrupted.DC test has only a kind of method of testing, and the test mode of connection of the present utility model is more, can be according to transformer different structure, different characteristics, use from three-phase to single-phase, from single-phase to zero sequence, from the low-voltage to the high voltage, even can use rated voltage test, shunting switch can not take place have defective and detect the possibility of not coming out.

Description of drawings

Fig. 1 is the circuit theory diagrams of an embodiment of the utility model.

The schematic diagram of three-phase frequency modulation AC power among Fig. 2 Fig. 1.

Fig. 3 is the schematic diagram of the utility model mutual inductor zero flux compensation circuit.

Embodiment

Below in conjunction with accompanying drawing content of the present utility model is described in detail.

As shown in Figure 1: the A phase signals of the three-phase frequency modulation AC power 1 of this pick-up unit is received on the A phase bushing of tested transformer 2 through A phase current mutual inductor 41, and A phase voltage mutual inductor 31 is received on the A phase bushing of tested transformer 2.The voltage transformer (VT) 31 of A phase, A phase voltage digital filtering shaping circuit 32, A phase synchronization signal high speed acquisition circuit 33 and A phase voltage signal conditioning data storage circuitry 34 join successively; A phase current mutual inductor 41, A phase current digital filtering shaping circuit 42, A phase synchronization signal high speed acquisition circuit 43, A phase current signal conditioning data storage circuitry 44 join successively; A phase voltage signal conditioning data storage circuitry 34 and current signal conditioning data storage circuitry 44 join with DSP digital processing circuit 5 again, DSP digital processing circuit 5 joins with the core control circuit 6 that the ARM9 processor constitutes, core control circuit 6 is connected with color liquid crystal touch display 7, printer 8 respectively, and core control circuit 6 also links to each other with communication interface 9 with three-phase frequency modulation experiment power supply 1 simultaneously.The B phase and the circuit identical (in figure do not draw) of C circuitry phase structure of pick-up unit with above-mentioned A phase.It is the TMS320VC element that DSP digital processing circuit 5 among Fig. 1 adopts model, it is S3C4210 that core control circuit 6 (ARM9) adopts model, digital filtering shaping circuit 32,42 adopts existing LC filtering in conjunction with the numerical software filter shape, synchronizing signal high speed acquisition circuit 33,43 adopts the AD637 element, and

data storage circuitry

34,44 adopts DDR-MT64V12128M8 large capacity digital storer.

During test, alternating current (experiment power supply), is received on the bushing of transformer 2 through current transformer by 1 output of three-phase frequency modulation AC power, receive the inner load ratio bridging switch main contact of transformer circuit through the bushing lead-in wire, constitute the test major loop through winding coil again.When load ratio bridging switch switches, alternating current and magnitude of voltage by major loop can change, the effect of current transformer 41 and voltage transformer (VT) 31 is that small-signal that the strong conversion of signals with major loop becomes to meet electronic circuit is given subsequent conditioning circuit and handled, carry out shaping filter through 32,42 pairs of small-signal ripples of digital filtering shaping circuit, convert analog quantity to digital quantity through synchronizing signal high

speed acquisition circuit

33,43,34,44 pairs of digital quantities of signal condition data storage circuitry are nursed one's health and are stored; DSP digital processing circuit 5 is that high-speed digital signal processing unit and ARM9 processor constitute, handling the back calculates quantification by 6 pairs of digital signals of core control circuit and is reduced into waveform by the demonstration of color liquid crystal touch display, or export by printer prints, control circuit also links to each other with communication interface 9 with three-phase frequency modulation experiment power supply 1 simultaneously, forms a complete automatic control test macro.

As shown in Figure 2: three-phase frequency modulation AC power comprises main circuit and controller 10.Main circuit adopts interchange-AC/DC structure, it comprises first order em filtering device 11 (electromagnetic interface filter), rectifier filer 12, inverter 13, isolating transformer 14, LC wave filter 15 and the second level em filtering device 16 (EMI low-pass filter) that joins successively, controller 10 is connected with aforesaid inverter 13, is used for phase place, frequency and the amplitude of control inverter 13 output voltages.

Single-phase AC civil power from electrical network is subjected to Disturbance in Power Net bigger, so earlier by first order em filtering device 11 (electromagnetic interface filter), interference is suppressed to electric network noise.Rectifier filer 12 adopts bridge rectifier filtering, and the alternating-current pulse ripple obtains DC voltage stably through electrochemical capacitor filtering, and this DC voltage converts alternating voltage to through inverter 13 (DC/AC change-over circuit).The inverter of this example is three cover separate single-phase inverters, controller 10 is the single-phase controllers of three covers, the single-phase controller of three covers is controlled three cover single-phase inverters respectively, the three phase AC sine wave voltage of output mutual deviation 120 degree, after power amplifier drives by isolating transformer 14 boosted voltages, through 15 filtering of LC filtering circuit, once more by obtaining desirable three-phase alternating current after em filtering device 16 low-pass filtering of the second level; The purpose that second level em filtering device 16 is set is further the high frequency interference that produces in this power circuit to be removed, and the waveform distortion of this power supply output is better than 0.5%.The output circuit of aforementioned three cover single-phase inverters is separate, exports at the secondary of isolating transformer 14 and can be connected into star, dihedral, single-phase needed alternating current on request.Owing to adopted three cover separate single-phase controllers, the arbitrary single phase poaer supply that all can be used as mutually in the three-phase supply of this example is independently used, and can adapt to any unbalance load, thereby improved the adaptive load ability of power supply greatly.

When needing different detection voltage, can set up high to low gear switch 17 at the output winding terminal of isolating transformer 14, change transformer output umber of turn and realize the different voltage transitions of output.

Aforesaid single-phase controller 10 can adopt the general purpose control circuit; as shown in Figure 2: soft start control is the conduction angle control to the thyristor of rectifier filer unit; commutating voltage is progressively raise; crystal oscillation circuit produces stabilizied reference frequency; sinusoidal wave circuit of triangle wave circuit and DDS (frequency synthesis) mode and SPWM circuit produce standard sine wave; SPWM control and holding circuit, feedback circuit are formed a closed-loop control system, driving circuit control inverter 14 outputs in the closed loop.

As shown in Figure 3: for accuracy of detection and the antijamming capability that improves mutual inductor, said voltage transformer (VT) 31 summation current transformers 41 place in the metallic shield shell, and these voltage transformer (VT) 31 summation current transformers 41 are equipped with zero flux compensation circuit, and said zero flux compensation circuit is by the compensating coil W on the mutual inductor iron core ₃With with this compensating coil W ₃The inverting amplifier 311 that connects is formed the output terminal of inverting amplifier 311 and mutual inductor secondary coil W ₂Serial connection.The induction electromotive force of compensating coil offsets with the induced potential of mutual inductor secondary coil after anti-phase through amplifying, and makes the magnetic flux in the transformer iron core approach zero, thereby has improved the precision of mutual inductor greatly.All the other numberings: W1 is the mutual inductor primary winding among Fig. 3, and R is the transformer secondary circuit load.

Claims

1, AC test device for transformer on-load tap-changer operating characteristic, comprise power supply, signal sampler, input treatment circuit that is connected with the sampling thief output terminal and demonstration output unit, it is characterized in that said power supply is a three-phase frequency modulation AC power (1), said signal sampler is voltage transformer (VT) (a 31) summation current transformer (41), said input treatment circuit is by the filtering shaping circuit (32 that connects successively, 42), synchronous signal acquisition circuit (33,43), data storage circuitry (34,44) and digital processing circuit (5) form, the output terminal of digital processing circuit (5) is connected with the demonstration output unit by core control circuit (6), and said voltage transformer (VT) summation current transformer is connected with tested transformer.

2, proving installation according to claim 1, it is characterized in that said three-phase frequency modulation AC power (1) comprises main circuit and controller (10), main circuit comprises first order em filtering device (11), rectifier filer (12), inverter (13), isolating transformer (14), LC wave filter (15) and the second level em filtering device (16) that joins successively, and the controller (10) that is used for phase place, frequency and the amplitude of control inverter 13 output voltages is connected with aforesaid inverter (13).

3, proving installation according to claim 2 is characterized in that said inverter (13) is three cover single-phase inverters, and controller (10) is the single-phase controllers of three covers.

4, proving installation according to claim 3, it is characterized in that said voltage transformer (VT) (31) summation current transformer (41) places in the metallic shield shell, and this voltage transformer (VT) (31) summation current transformer (41) is equipped with zero flux compensation circuit, and said zero flux compensation circuit is by the compensating coil (W on the mutual inductor iron core ₃) and with this compensating coil (W ₃) inverting amplifier (311) that connects forms the output terminal of inverting amplifier and mutual inductor secondary coil (W ₂) serial connection.