CN104330637B - 500KV transformer direct-current resistance and direct-current demagnetization intelligent test method - Google Patents

Abstract

The invention discloses a 500KV transformer DC resistance and DC demagnetization intelligent tester, including a rectifier circuit, a polarity adjustable circuit, an inverter circuit, a constant current source module, a DSP control module, a standard sampling resistor, an AD data collector, and a The microprocessor and display used to control the display; the rectifier circuit, the polarity adjustable circuit, the inverter circuit, the DSP control module, and the constant current source module are connected in sequence, and the standard sampling resistor is connected between the DSP control module and the constant current source module. During the period, the AD data collector, the microprocessor and the display are connected sequentially, and the rectification circuit is connected with the display. The present invention realizes the single-phase and three-phase DC resistance test, shortens the DC test time of the DC resistance test of the transformer, and integrates the DC demagnetization Function, large current can be used on site for DC resistance test, shorten test time, and demagnetize in time after test, save a lot of time for dismantling and installation, and improve work efficiency.

Description

500KV Transformer DC Resistance and DC Demagnetization Intelligent Test Method

technical field

The invention relates to the field of transformer DC resistance testing, in particular to a 500KV transformer DC resistance and DC demagnetization intelligent tester and method.

Background technique

Some existing DC resistance testers in the industry do not have the function of DC demagnetization. During the test, a large current cannot be used to test the DC resistance. The test time is long, and the demagnetization cannot be performed in time after the test. The residual magnetism endangers the normal use of the equipment.

When the prior art DC resistance tester tests the DC resistance of the three-phase transformer, the test method of the single-phase measurement mode is used to test the resistances of the transformers AN, BN, and CN respectively, and the test current flows from A, B, and C to the N phase. The lead resistance of the neutral point N to the resistance of each winding can be accurately tested. However, when using the three-phase simultaneous measurement method, the test current of the instrument flows from A, C to B, and the neutral point N does not have current flow, so the resistance of the transformers AN, BN, and CN measured by the instrument does not include The contact resistance of the neutral lead. Therefore, the AN (BN, CN) resistance must be measured by a single-phase measurement method before the three-channel direct resistance test, which is inconvenient and inefficient. Moreover, it is impossible to use a larger current for the DC resistance test in the existing DC resistance test. It takes a long time to demagnetize in time after the test.

Contents of the invention

The invention rectifies the alternating current through the rectifier circuit and outputs the direct current, realizes the constant current source output of the A, B, and C three-phase currents through the polarity adjustable circuit, the inverter circuit, and the constant current source module, and realizes single-phase testing, three-phase testing and DC demagnetization.

500KV transformer DC resistance and DC demagnetization intelligent tester, including rectification circuit, polarity adjustable circuit, inverter circuit, constant current source module, DSP control module for maintaining constant current output of constant current source module, standard sampling resistor, AD data collector, microprocessor and display for controlling the display of the display.

The rectifier circuit, polarity adjustable circuit, inverter circuit, DSP control module, and constant current source module are connected sequentially. The standard sampling resistor is connected between the DSP control module and the constant current source module. AD data collector, microprocessor and The display is connected sequentially, the rectifier circuit is connected with the display, the output terminal of the constant current source module, the output terminal of the inverter circuit, and the input terminal of the AD data collector are connected with the transformer under test.

The polarity adjustable circuit includes a first triode, a second triode, a third triode, a fourth triode, a resistor R, an inductance L and an inductance Ld, an inductance Ld, the first triode, a resistor R , inductance L, and the fourth triode are sequentially connected in series; inductance Ld, the third triode, inductance L, resistance R, and the second triode are sequentially connected in series, the first triode, the second triode The conduction directions of the third, third and fourth triodes are connected in the same direction, and the empty terminals of the second and fourth triodes are connected.

The non-contact ends of the resistance R and the inductance L connected in series are polarity-adjustable current output ends; the free-connection end of the inductance Ld and the second triode are the current input ends.

The first triode, the second triode, the third triode and the fourth triode are all unidirectional thyristors.

The turn-on voltages of the first triode, the second triode, the third triode and the fourth triode are all 0.7V.

The constant current power of the constant current source module is 1.2kW, the effective value of the output voltage is 24-48V, and the current is 2.5-25A.

The input end of the rectification circuit is connected with the mains voltage.

500KV transformer DC resistance and DC demagnetization intelligent test method, including the following steps,

S01, configure transformer DC test as single-phase measurement or three-phase measurement, when configured as single-phase test, DSP control module controls constant current source module A phase, B phase, C phase current output phase by phase; when configured as three-phase test , the DSP control module controls the current of phase A, phase B and phase C of the constant current source module to output simultaneously;

S02, the standard sampling resistor converts the current output by the constant current source module into a voltage signal, and sends the voltage signal to the DSP control module, and the DSP control module compares the voltage signal with the preset voltage value to maintain the current of the constant current source module Constant current output; the standard sampling resistor converts the current output by the constant current source module into a voltage signal, and the output current of the constant current source module generates a voltage U1 through the standard sampling resistor. U1 is compared with the preset standard voltage U2. If U1>U2, then The DSP control module controls the constant current source module to reduce the output current, and if U1<U2 controls the constant current source module to increase the output current;

S03, the AD data collector collects the winding voltage and current data of the transformer, the microprocessor calculates the DC resistance of the transformer through the winding voltage and current, and controls the display to display the calculation result through the microprocessor;

S04, the polarity adjustable circuit receives the DC input U _d of the rectifier circuit, and switches the resistance R and the inductance L by turning on the first triode, the fourth triode, the second triode, and the third triode in turn The polarity of the current at both ends, the two ends of the resistor R and the inductor L are adjustable polarity DC output, which realizes the adjustable polarity of the current output, and sends the current output of the polarity change to the constant current source module, and outputs the positive and negative changes DC current, to realize the control of the DC current applied to the transformer winding to continuously change the polarity, and at the same time the amplitude is gradually reduced, and the hysteresis loop of the core is gradually reduced to achieve the purpose of eliminating the residual magnetism. The demagnetization current is passed into the high voltage winding of the transformer under test, the demagnetization current is not less than the test current of the high voltage winding, and the current value is reduced by 5% to 10% each time, until the current is 0.5mA, the DC demagnetization ends.

Compared with the prior art, the present invention includes the following beneficial effects, can realize single-phase and three-phase DC resistance test, shorten the DC test time of transformer DC resistance test, and improve work efficiency; High current for DC resistance test, shorten test time, and demagnetize in time after test, avoid using other devices for demagnetization, save a lot of time for dismantling and installation, and improve work efficiency.

After the mains is connected externally, through the polarity adjustable circuit and the inverter circuit, the direction changes and the current value decreases step by step, and the DC demagnetization is completed, realizing the integration of the DC resistance test and the DC demagnetization function.

Description of drawings

Fig. 1 structural representation of 500KV transformer DC resistance and DC demagnetization intelligent tester of the present invention;

Figure 2 is a schematic diagram of the structure of the polarity adjustable circuit.

detailed description

The present invention will be described in further detail below in conjunction with the accompanying drawings and specific embodiments.

As shown in Figure 1, the present invention proposes a 500KV transformer DC resistance and DC demagnetization intelligent tester, including a rectifier circuit, a polarity adjustable circuit, an inverter circuit, a constant current source module, and is used to keep the output of the constant current source module constant Current DSP control module, standard sampling resistor, AD data collector, microprocessor and display for controlling display display.

The rectifier circuit, polarity adjustable circuit, inverter circuit, DSP control module, and constant current source module are connected sequentially. The standard sampling resistor is connected between the DSP control module and the constant current source module. AD data collector, microprocessor and The display is connected sequentially, the rectifier circuit is connected with the display, the output terminal of the constant current source module, the output terminal of the inverter circuit, and the input terminal of the AD data collector are connected with the transformer under test, and the DC output of the rectifier circuit provides power for the display .

The polarity adjustable circuit includes a first triode VT1, a second triode VT2, a third triode VT3, a fourth triode VT4, a resistor R, an inductance L and an inductance Ld, an inductance Ld, a first triode The tube VT1, the resistor R, the inductor L, and the fourth transistor VT4 are sequentially connected in series; the inductor Ld, the third transistor VT3, the inductor L, the resistor R, and the second transistor VT2 are sequentially connected in series, and the first and third transistors are sequentially connected in series. The conduction directions of the transistor VT1, the second transistor VT2, the third transistor VT3, and the fourth transistor VT4 are connected in the same direction, and the empty terminals of the second transistor VT2 and the fourth transistor VT4 are in phase connect.

As shown in Figure 2, the inductance Ld is connected to the anode A of the first triode VT1 and the third triode VT3, and the cathodes of the first triode VT1 and the third triode VT3 are respectively connected to the anode A of the second triode The anodes of VT2 and the fourth triode VT4 are connected, that is, the cathode of the first triode VT1 is connected with the anode of the second triode VT2, that is, the cathode of the third triode VT3 is connected with the anode of the fourth triode VT4 , the cathode of the second triode VT2 is connected to the cathode of the fourth triode VT4, the resistor R and the inductor L are connected in series, and the two ends are respectively connected to the anodes of the second triode VT2 and the fourth triode VT4, the first The control poles of the triode VT1 , the second triode VT2 , the third triode VT3 and the fourth triode VT4 are all open-connected. When the first triode VT1 and the fourth triode VT4 are turned on, the load is positive voltage; when the second triode VT2 and the third triode VT3 are turned on, the load is negative voltage, and the load is turned on Switch the polarity of the current through VT1, VT4 or VT2, VT3, adjust the polarity of the current source of the access circuit through the polarity adjustable circuit, and constantly change the polarity of the DC current applied to the winding.

The non-contact ends of the resistance R and the inductance L connected in series are polarity-adjustable current output ends; the free connection end of the inductance Ld and the second triode VT2 are current input ends.

The first triode VT1 , the second triode VT2 , the third triode VT3 , and the fourth triode VT4 are all unidirectional thyristors.

The conduction voltages of the first triode VT1, the second triode VT2, the third triode VT3, and the fourth triode VT4 are all 0.7V, and the current is switched by turning on VT1, VT4 or VT2, VT3 in turn. polarity.

The constant current source module is a high-power constant current source module, the constant current power is 1.2kW, the effective value of the output voltage is 24-48V, and the current is 2.5-25A.

The input terminal of the rectification circuit is connected with the mains voltage.

500KV transformer DC resistance and DC demagnetization intelligent test method, including the following steps,

S01, configure transformer DC test as single-phase measurement or three-phase measurement, when configured as single-phase test, DSP control module controls constant current source module A phase, B phase, C phase current output phase by phase; when configured as three-phase test , the DSP control module controls the current of phase A, phase B and phase C of the constant current source module to output simultaneously;

S02, the standard sampling resistor converts the current output by the constant current source module into a voltage signal, and sends the voltage signal to the DSP control module, and the DSP control module compares the voltage signal with the preset voltage value to maintain the current of the constant current source module Constant current output; the standard sampling resistor converts the current output by the constant current source module into a voltage signal, and the output current of the constant current source module generates a voltage U1 through the standard sampling resistor. U1 is compared with the preset standard voltage U2. If U1>U2, then The DSP control module controls the constant current source module to reduce the output current, and if U1<U2 controls the constant current source module to increase the output current;

S03, the AD data collector collects the winding voltage and current data of the transformer, the microprocessor calculates the DC resistance of the transformer through the winding voltage and current, and controls the display to display the calculation result through the microprocessor;

S04, the polarity adjustable circuit receives the DC input U _d of the rectifier circuit, and switches the resistance by turning on the first transistor VT1, the fourth transistor VT4, the second transistor VT2, and the third transistor VT3 in turn The current polarity at both ends of R and inductor L, the polarity adjustable DC output at both ends of resistor R and inductor L, realizes adjustable current output polarity, and sends the current output with polarity change to the constant current source module, and the output is positive The reverse changing DC current realizes the control of the DC current applied to the transformer winding to continuously change the polarity, and at the same time the amplitude decreases gradually, and the hysteresis loop of the core is gradually reduced to achieve the purpose of eliminating the residual magnetism. The demagnetization current is passed into the high voltage winding of the transformer under test, the demagnetization current is not less than the test current of the high voltage winding, and the current value is reduced by 5% to 10% each time, until the current is 0.5mA, the DC demagnetization ends.

When the test starts, select the DC test mode on the operation interface, select the corresponding test, control the constant current source module to output the DC current required for the test through the DSP control module, obtain the transformer test data through the 14-bit AD data collector, and process it through the microcomputer The system automatically calculates the result, which is the DC resistance of the transformer, and displays it on the LCD screen. After a test is completed, you can continue to perform a different test or repeat the previous test by selecting the DC test mode. Through the polarity adjustable circuit to control the output of positive and negative DC current changes, so as to achieve the purpose of transformer demagnetization. After the demagnetization is completed, the overall test is completed.

Those skilled in the art can make changes or modifications to the present invention without departing from the spirit and scope of the present invention. Therefore, if these modifications and variations of the present invention fall within the technical scope of the claims of the present invention and equivalents thereof, the present invention is also intended to include these modifications and variations.

Claims (3)

1.500KV DCR of Transformer and direct current degaussing intelligent test method, it is characterised in that comprise the following steps,

S01, configuration transformer dc test is single-phase measurement or three-phase measurement, when single-phase test is configured to, DSP control moulds Block control constant-current source modules A phase, B phases, C phase currents are by mutually exporting；When three-phase test is configured to, DSP control module control is permanent Stream source module A phase, B phase, C phase electric current is exported simultaneously；

The electric current that constant current source module is exported is converted to voltage signal by S02, standard sample resistance, and the voltage signal is sent To DSP control module, be compared for the voltage signal and the magnitude of voltage for pre-setting by DSP control module, keeps constant-current source The electric current constant current output of module；

S03, AD data acquisition unit gather winding voltage, the current data of transformer, and microprocessor is by the winding voltage, electricity Stream calculation DCR of Transformer, controls display to show result of calculation by microprocessor；

S04, polarity conditioned circuit receives the direct current input U of rectification circuit_d, by turning on the first triode (VT1), the 4th in turn Triode (VT4) and the second triode (VT2), the 3rd triode (VT3) come convert resistance R, inductance L two ends current polarity, electricity Resistance R, inductance L two ends are adjustable polarity direct current output, realize that electric current output polarity is adjustable, and the electric current of the change in polarity is defeated Go out to be sent to constant-current source module, export the DC current of forward and reverse change, realize that control is applied to the direct current in Transformer Winding Electric current constantly changes polarity, while amplitude gradually reduces, gradually reduces the hysteresis ring of iron core, reaches the purpose for eliminating remanent magnetism.

2. 500KV DCR of Transformer according to claim 1 and direct current degaussing intelligent test method, its feature exist In, the step S04 specifically includes following steps,

Demagnetizing current is passed through in tested transformer high-voltage winding, the demagnetizing current is not less than the test electric current of high pressure winding, often Primary current value reduction by 5%~10%, until when electric current is 0.5mA, direct current degaussing terminates.

3. 500KV DCR of Transformer according to claim 1 and direct current degaussing intelligent test method, its feature exist In, the S02 specifically includes following steps, and the electric current that constant current source module is exported is converted to voltage signal by standard sample resistance, Constant-current source module output current produces voltage U1, U1 compared with preset standard voltage U2, if U1 by standard sample resistance>U2, Then DSP control module control constant current source module reduces output current, if U1<U2 then controls constant current source module to increase output current.