CN113203926A - Direct-current withstand voltage tester and method for inter-phase lap joint water conduit of water-cooled generator - Google Patents

Direct-current withstand voltage tester and method for inter-phase lap joint water conduit of water-cooled generator Download PDF

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CN113203926A
CN113203926A CN202110475642.7A CN202110475642A CN113203926A CN 113203926 A CN113203926 A CN 113203926A CN 202110475642 A CN202110475642 A CN 202110475642A CN 113203926 A CN113203926 A CN 113203926A
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water
leakage current
current
voltage
phase
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CN113203926B (en
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慎志勇
杨新志
李伟
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China Yangtze Power Co Ltd
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    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
    • G01R31/00—Arrangements for testing electric properties; Arrangements for locating electric faults; Arrangements for electrical testing characterised by what is being tested not provided for elsewhere
    • G01R31/12—Testing dielectric strength or breakdown voltage ; Testing or monitoring effectiveness or level of insulation, e.g. of a cable or of an apparatus, for example using partial discharge measurements; Electrostatic testing
    • G01R31/14—Circuits therefor, e.g. for generating test voltages, sensing circuits
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
    • G01R1/00—Details of instruments or arrangements of the types included in groups G01R5/00 - G01R13/00 and G01R31/00
    • G01R1/02—General constructional details
    • G01R1/18—Screening arrangements against electric or magnetic fields, e.g. against earth's field
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
    • G01R1/00—Details of instruments or arrangements of the types included in groups G01R5/00 - G01R13/00 and G01R31/00
    • G01R1/20—Modifications of basic electric elements for use in electric measuring instruments; Structural combinations of such elements with such instruments
    • G01R1/22—Tong testers acting as secondary windings of current transformers
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
    • G01R31/00—Arrangements for testing electric properties; Arrangements for locating electric faults; Arrangements for electrical testing characterised by what is being tested not provided for elsewhere
    • G01R31/34—Testing dynamo-electric machines
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
    • G01R31/00—Arrangements for testing electric properties; Arrangements for locating electric faults; Arrangements for electrical testing characterised by what is being tested not provided for elsewhere
    • G01R31/34—Testing dynamo-electric machines
    • G01R31/346—Testing of armature or field windings
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
    • G01R31/00—Arrangements for testing electric properties; Arrangements for locating electric faults; Arrangements for electrical testing characterised by what is being tested not provided for elsewhere
    • G01R31/50—Testing of electric apparatus, lines, cables or components for short-circuits, continuity, leakage current or incorrect line connections
    • G01R31/52—Testing for short-circuits, leakage current or ground faults
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
    • G01R31/00—Arrangements for testing electric properties; Arrangements for locating electric faults; Arrangements for electrical testing characterised by what is being tested not provided for elsewhere
    • G01R31/50—Testing of electric apparatus, lines, cables or components for short-circuits, continuity, leakage current or incorrect line connections
    • G01R31/72—Testing of electric windings
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
    • G01R35/00—Testing or calibrating of apparatus covered by the other groups of this subclass
    • G01R35/005—Calibrating; Standards or reference devices, e.g. voltage or resistance standards, "golden" references

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  • General Physics & Mathematics (AREA)
  • Engineering & Computer Science (AREA)
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Abstract

The direct-current withstand voltage tester comprises a control and signal processing box, a high-voltage generating device and a signal collecting box, wherein the control and signal processing box receives a power supply and controls the high-voltage generating device to generate a set high voltage, the high-voltage generating device feeds a current value back to the control and signal processing box through a measuring terminal, the tester shields a water inlet/outlet collector pipe, a non-pressurized phase cross-connection water guide pipe and an interphase leakage current through a shielding method, measures the water inlet/outlet collector pipe, the non-pressurized phase cross-connection water guide pipe and the interphase leakage current respectively, then calculates the pure water conductive current passing through the water guide pipe through pure water conductivity and water guide pipe parameters, calibrates a calculated value of the water guide pipe by using a flexible pincerlike ammeter to obtain a real conductive current of the interphase cross-connection water guide pipe, and then subtracts the partial current from the interphase shielding total current to obtain a real interphase leakage current value, thereby really achieving the purpose of performing direct-current withstand voltage and leakage current tests on the water-cooled generator with the interphase cross-connection water guide pipes In (1).

Description

Direct-current withstand voltage tester and method for inter-phase lap joint water conduit of water-cooled generator
Technical Field
The invention relates to the field of generator detection equipment, in particular to a direct-current voltage resistance tester and a direct-current voltage resistance test method for an internal water-cooled generator with water diversion pipes lapped with each other.
Background
At present, direct current leakage and voltage withstand tests of a generator stator winding are important means for detecting the insulation state of a generator and ensuring safe and stable operation of a unit, and although the methods of the direct current leakage and the voltage withstand tests are the same, the former mainly examines the insulation tolerance strength, and the latter mainly examines the insulation state. In particular, the test project has incomparable advantages compared with alternating-current withstand voltage for detecting the insulation defect of the winding insulation end part of the generator.
The conventional generator generally uses direct current withstand voltage test equipment to test the withstand voltage and leakage current of a unit. For the water-cooled generator, pure water is introduced into the generator set, the relative current ratio of the pure water is low, and a special direct-current leakage instrument for the water-cooled generator is generally used for testing. The test instrument adopts a shielding method, so that the current of the water collecting pipe is tested in a shielding mode through a special shielding terminal. As pure water pipes are lapped at intervals on a water-cooled generator of a certain power plant, the lapped pure water pipes have large leakage current in the voltage-resisting process, the current cannot be shielded by using a conventional testing instrument, so that the measuring range of the testing instrument seriously exceeds the standard, and when voltage is not added to testing voltage, the instrument protection is started, so that the test cannot be carried out. Meanwhile, even if the measuring range is increased, the data precision can be misled greatly, and meanwhile, the pure water leakage current cannot be eliminated from the test result, whether the insulation condition of the unit coil bar is good or not cannot be judged, so that the whole test cannot be carried out.
Disclosure of Invention
The invention aims to solve the technical problem of providing a direct-current voltage resistance tester and a direct-current voltage resistance test method for an internal water-cooled generator with interphase lapping water pipes, wherein the tester completely shields the leakage current of a non-pressurized phase on the basis of a shielding method, but the test method can only test the insulation condition of the opposite ground and cannot test the insulation condition of the interphase, so that an interphase current measuring meter is added to the tester on the basis, a high-precision flexible pincerlike ammeter is used for testing the current of a single water pipe, the value and the theoretical calculation lapping water pipe pure water leakage current value are used for checking, the final pure water conductivity in the actual test process is determined, and the value is used as the standard for carrying out program mathematical calculation, thereby ensuring the data accuracy. The method can effectively eliminate the current of the alternate lapped water conduit, and can test the actual alternate and relative leakage current on the basis of ensuring the smallest possible instrument test capacity, thereby conveniently solving the problem that the generator of the alternate lapped water conduit cannot carry out direct current withstand voltage and leakage test.
In order to solve the technical problems, the technical scheme adopted by the invention is as follows:
a DC withstand voltage tester for an internal water-cooled generator with alternatively lapped water pipes comprises a control and signal processing box, a high voltage generating device and a signal collecting box, wherein the control and signal processing box receives a power supply and controls the high voltage generating device to generate a set high voltage, the high voltage generating device feeds current values back to the control and signal processing box through a measuring terminal, a shielding end of the high voltage generating device is electrically connected with a water collecting pipe and the signal collecting box, a high voltage output end of the high voltage generating device is electrically connected with a stator winding of a pressurized phase, the signal collecting box is connected with stator windings of the remaining two non-pressurized phases through a first non-pressurized connecting cable and a second non-pressurized connecting cable, the end parts of the first non-pressurized connecting cable and the second non-pressurized connecting cable are provided with clamp-shaped ammeters, the stator winding of the non-pressurized phase penetrates through the clamp-shaped ammeters, and a single lapped water pipe connecting cable on the signal collecting box is connected with a single lapped water pipe, the first non-pressurized connecting cable, the second non-pressurized connecting cable and the single lapped water conduit connecting cable are connected with a current measuring unit in the signal collecting box, the signal collecting box sends various measured current values to the control and signal processing box, the control and signal processing box calculates the total leakage current of the lapped water conduit according to the measured leakage current of the single lapped water conduit, and then calculates the total leakage current of the pressurized phase by combining the measured insulation leakage currents at intervals.
The signal acquisition box is electrically connected with a grounding resistor of the stator winding of the pressurizing phase, the grounding resistor is a loop resistor formed by grounding of the iron core, and the signal acquisition box acquires the leakage current of the pressurizing phase and sends the value to the control and signal processing box.
The shield connection of the water collecting pipe is provided with a pure water polarization potential compensation circuit.
The control and signal processing box is in communication connection with a computer.
The single lap joint water conduit connecting cable is electrically connected with the single lap joint water conduit through the pincerlike ammeter, and the pincerlike ammeter measures the leakage current of the single lap joint water conduit and sends the value to the control and signal processing box.
The control and signal processing box is internally provided with an intermediate frequency voltage doubling control circuit and a data processing unit, the intermediate frequency voltage doubling control circuit is internally provided with a PWM (pulse width modulation) circuit, the PWM circuit outputs signals to control an IGBT (insulated gate bipolar transistor) device of the high-voltage generating device and generate set high voltage, and the data processing unit receives voltage and current analog signals measured by the high-voltage generating device and the signal acquisition box, converts the voltage and current analog signals into digital signals and transmits the digital signals to a computer.
The pressure resistance test method of the direct current pressure resistance tester of the water-cooled generator using the alternate lap joint water conduit comprises the following specific steps:
step one, the control and signal processing box controls the high-voltage end of the high-voltage generating device to be boosted to reach a set test high voltage, and the signal acquisition box acquires A-phase leakage current value I and C-phase leakage current value I under voltage U through a current measurement unit connected with a first non-pressurized connecting cable, a second non-pressurized connecting cable and a single lap joint water conduit connecting cable1Leakage current values of A and B phases I2A and B interphase single lap joint water conduit leakage current measurement value I3And A relative earth leakage current value I4And transmitting the measured value to the computer;
step two, the computer calculates the measured current value, and the A, C interphase insulation leakage current value is:
IAC＝I1-NI3
A. the phase-to-phase insulation leakage current is as follows:
IAB＝I2-MI3
wherein N, M is A, C alternate lap penstocks and A, B alternate lap penstocks total number respectively, obtains A looks total leakage current from above and is:
IA＝IAB+IAC+I4。
the leakage current measurement value I of the A and B interphase single lapped water conduit3Comparing the measured value with a calculated theoretical value I' during the test, when I3And when the I 'does not exceed the set range, using the I' as the leakage current measured value of the single lapped water conduit between the phases A and B, wherein the insulation leakage current value between the phases A, C at the time is as follows:
IAC＝I1-NI′
A. the phase-to-phase insulation leakage current is as follows:
IAB＝I2-MI′
wherein N, M is A, B alternate lap penstocks and A, C alternate lap penstocks total number respectively, obtains A looks total leakage current from above and is:
IA＝IAB+IAC+I4＝I1+I2+I4-NI′-MI′
when I is3When the difference value is compared with I' and exceeds the set range, the pure water resistivity of the single lapped water conduit measured at the moment is checked, and when no error is confirmed, I is used3And (4) as a measured value of the leakage current of the single lapped water conduit between the phase A and the phase B, if an error exists, setting the actual pure water resistivity again, and recalculating and determining again.
The method for calculating the theoretical value I' of the leakage current of the single lap joint water conduit comprises the following steps:
the pure water conductivity to the water conduit is surveyed, is marked as sigma, looks up the length L of alternate single overlap joint water conduit, and the pure water intraductal radius is r, inputs the parameter to the computer, and the equivalent resistance who calculates single overlap joint water conduit is:
Figure BDA0003046978990000031
in setting upUnder the test high voltage U, the theoretical leakage current value of a single lapped water conduit is as follows:
Figure BDA0003046978990000032
the invention provides a direct-current withstand voltage tester and a direct-current withstand voltage test method for an inter-phase lapped water diversion generator, wherein the tester shields a water inlet/outlet water collecting pipe, a non-pressurized phase crossed water diversion pipe and inter-phase leakage currents by a shielding method, measures the currents respectively, calculates the pure water conductive current passed by the water diversion pipe under the test voltage according to the pure water conductivity, the length of the water diversion pipe and the radius parameters, calibrates the test value and the calculated value by using a flexible pincerlike ammeter to obtain the real conductive current of the inter-phase lapped water diversion pipe, and subtracts the current from the total inter-phase shielding current to obtain the actual inter-phase leakage current value, thereby really achieving the purpose of performing direct-current withstand voltage and leakage current tests on the inter-phase lapped water diversion generator by the non-pressurized phase shielding method.
Drawings
The invention is further illustrated by the following examples in conjunction with the accompanying drawings:
FIG. 1 is a schematic view of the connection structure of the device of the present invention;
FIG. 2 is a schematic circuit diagram of the DC withstand voltage tester of the present invention;
FIG. 3 is an equivalent circuit diagram of phase A pressurization;
FIG. 4 is a control schematic diagram of the high voltage generating apparatus;
FIG. 5 is a software program diagram for withstand voltage test in a computer.
Wherein: a control and signal processing box 1, a high voltage generating device 2, a signal collecting box 3, a catchment pipe 4, a stator winding 5, a computer 6, a first non-pressurized connecting cable 7, a second non-pressurized connecting cable 8, a single lapped diversion pipe connecting cable 9, a pure water polarization potential compensation circuit 10, equivalent insulation resistance R1 between the diversion pipe equivalent resistance R, A of the inlet and the outlet of the catchment pipe and the phase C, equivalent insulation resistance R2 between the phase A and the phase B, lapped diversion pipe equivalent total resistance R3 between the phase A and the phase B, lapped diversion pipe equivalent total resistance R4 between the phase A and the phase C,Measuring equivalent resistance R5 of water conduit by single lap joint between A phase and B phase, equivalent resistance R6 of A phase to ground, and leakage current value I of A phase and C phase1Leakage current values of A and B phases I2A and B interphase single lap joint water conduit leakage current measurement value I3A relative earth leakage current value I4Leakage current value I of inlet and outlet water collecting pipe5Total shielding current I6Total leakage current value I7。
Detailed Description
The technical scheme of the invention is explained in detail in the following by combining the drawings and the embodiment.
As shown in fig. 1-5, the dc withstand voltage tester for the internal water-cooled generator with the alternatively lapped water conduit comprises a control and signal processing box 1, a high voltage generating device 2 and a signal collecting box 3, wherein the control and signal processing box 1 receives power and controls the high voltage generating device 2 to generate a set high voltage, the high voltage generating device 2 feeds back the current value to the control and signal processing box 1 through a measuring terminal, the shielding end of the high voltage generating device 2 is electrically connected with a water collecting pipe 4 and the signal collecting box 3, the high voltage output end of the high voltage generating device 2 is electrically connected with a stator winding 5 of a pressurized phase, the signal collecting box 3 is connected with the stator winding 5 of the other two non-pressurized phases through a first non-pressurized connecting cable 7 and a second non-pressurized connecting cable 8, the ends of the first non-pressurized connecting cable 7 and the second non-pressurized connecting cable 8 are provided with a clamp-shaped ammeter, the non-pressurized phase stator winding passes through a pincerlike ammeter, a single lapped water conduit connecting cable 9 on the signal acquisition box 3 is connected with a single lapped water conduit, a first non-pressurized connecting cable 7, a second non-pressurized connecting cable 8 and the single lapped water conduit connecting cable 9 are connected with a current measuring unit in the signal acquisition box 3, the signal acquisition box 3 sends various measured current values to the control and signal processing box 1, the control and signal processing box 1 calculates the total leakage current of the lapped water conduits according to the measured leakage current of the single lapped water conduit, and then calculates the total leakage current of the pressurized phase by combining the measured insulation leakage currents at different phases.
The program is developed by Microsoft Visual studio 2008C # and Microsoft Office 2008, the interface is provided with protection voltage setting and protection current setting, and the parameters of the inner diameter, the length, the pure water conductivity and the quantity of the pure water pipes of the water conduit are set, the pure water resistance calculation formula of unit length is arranged inside, and the resistance of the pure water can be automatically calculated only by inputting the length, the inner diameter and the pure water conductivity of the pure water pipes; in the mode, for the generator which is normally calculated without error or completes the test in a short time, the ratio of the voltage to the resistance can automatically calculate the current size because the test is a direct current test, the capacitive sound effect does not exist, and the whole pressurizing phase conductor bar does not have the condition of unequal voltage, namely the test voltage value is the voltage of the conductor bar; generally, the pure water system of the generator can not be stopped in the test, the conductivity of the pure water can always be reduced, in order to ensure the reality and accuracy of the data and prevent data errors caused by other conditions, the test instrument is also provided with a high-precision flexible clamp ammeter which is connected to a cross-over water conduit in the test process, a calculated value is calibrated at the beginning of the test, in order to ensure the safety, in the process of confirming the actual conductivity of the pure water, the pressure value of the test equipment is 5kV voltage under the low voltage level, the test safety can be ensured, the time is short, the tested equipment is not damaged, the pure water current can be completely detected under the 5kV voltage, the time value is also small, the selection and the improvement of the precision of the clamp ammeter are facilitated, the test value and the calculated value standard of the water conduit are set by an internal program of the test instrument to be 5 muA, if the error of the test value and the calculated value is not more than 5 muA, the pure water that uses the calculated value to be accurate certain unit normal water conduit is under the highest test voltage 40kV, the leakage current value is roughly about 500 muA, there are 6 overlap joint water conduits at the alternate, every water conduit has about 125 muA at the highest voltage pressure leakage current value roughly, under 5kV voltage, only 1/8 of its electric current, consequently the calculated value can be confirmed completely to the difference 5 muA and the measured value is wrong, also can reduce the range of pincerlike ampere meter, the cost is saved, if the measured value and the calculated value error of pincerlike meter reach 5 microamperes in the test procedure, the instrument automatic suggestion needs artifical supplementary help. Firstly, whether the pure water parameters are wrong with the initial values or not is judged, if the pure water parameters are adjusted, other lapped water guide pipes can be replaced for testing again if no faults exist, if the errors are out of tolerance, the influences of pure water polarization and the like can be caused, and the standard can be determined according to the test values.
The high-voltage generating device 2 adopts a cascade rectification circuit to realize high-voltage output. The capacity of the instrument is limited, the conductivity of pure water is required to be not more than 0.5 mu s/cm, and if the conductivity exceeds the capacity of required equipment, the volume of the double-pressure cylinder is too large to be suitable for field application. Under the conductivity, the current of the water conduit of a single lapped water conduit can not exceed 1 milliampere under the maximum test voltage, so that the measurement precision of the clamp-on ammeter under a small range can be ensured.
The signal acquisition box 3 mainly has non-pressurized phase current signals and current signals of a clamp-on ammeter, and high voltage can be brought in if a loop is open in the non-pressurized phase test process, so the test input lines of the circuit are high-voltage-resistant pressurizing lines and are connected with an instrument box, and meanwhile, the lines are conveniently reversed in the test process, the pressurizing lines use silica gel high-voltage lines, the ends of the silica gel high-voltage lines are connected with a ground wire with 0.5 m exposed metal, the silica gel high-voltage lines are conveniently connected with the end of a generator stator, and the connected ground wire heads are fixed by soldering tin to prevent the ground wire heads from scattering. After the two currents of the non-voltage phases are measured, the two currents are connected with a shielding terminal of the voltage doubling cylinder after being short-circuited in the equipment, and the connecting wire is a high-voltage-resistant test wire. The ammeter has the range of 5mA and the precision of 1 muA because of the precision of the electronic ammeter for testing, thereby ensuring the testing precision.
As shown in fig. 3, the signal collection box 3 is electrically connected to the equivalent resistor R6 of a phase a of the stator winding 5 of the voltage phase, the grounding resistor R6 is a loop resistor formed by grounding the core, and the value I of the leakage current of a phase a to the ground is collected4And sends the values to the control and signal processing box 1.
As shown in fig. 2, the above-mentioned shield connection of the water collecting pipe 4 is provided with a pure water polarization potential compensation circuit 10.
As shown in fig. 1, the control and signal processing box 1 is connected to a computer 6 in communication.
The single lapped water conduit connecting cable 9 is electrically connected with the single lapped water conduit through a pincerlike ammeter, and the pincerlike ammeter measures the leakage current of the single lapped water conduit and sends the value to the control and signal processing box 1.
As shown in fig. 4, a PWM pulse width modulation circuit is arranged in the intermediate frequency voltage doubling control circuit, the PWM pulse width modulation circuit outputs a signal to control an IGBT device of the high voltage generator 2, the voltage doubling cylinder outputs a voltage to generate a set high voltage, a measurement control and protection device is arranged in the intermediate frequency voltage doubling control circuit, the maximum protection output voltage is 80kv, the output current is 200mA, the maximum protection of the test current is 2000 μ a, and the data processing unit receives voltage and current analog signals measured by the high voltage generator 2 and the signal collection box 3, converts the voltage and current analog signals into digital signals, and transmits the digital signals to the computer 6.
As shown in fig. 3, the method for testing the direct current withstand voltage of the internal water-cooled generator using the inter-phase lap joint conduit comprises the following specific steps:
step one, the control and signal processing box 1 controls the high-voltage end of the high-voltage generating device 2 to be boosted to reach the set test high voltage, and the signal acquisition box 3 acquires the phase A and phase C leakage current value I under the voltage U through a current measurement unit connected with a first non-pressurized connecting cable 7, a second non-pressurized connecting cable 8 and a single lapped water conduit connecting cable 91Leakage current values of A and B phases I2A and B interphase single lap joint water conduit leakage current measurement value I3And A relative earth leakage current value I4And transmits the measured value to the computer 6;
the above measured A and C phase leakage current values I1Involving leakage current between phases
Step two, the computer 6 calculates the measured current value, the leakage current value I of the A phase and the C phase1The leakage current value of the lap joint water conduit between the A-phase stator winding and the C-phase stator winding is included, so that the A, C interphase insulation leakage current value is as follows:
IAC＝I1-NI3
leakage current values of A and B phases I2The leakage current value of a lap joint water pipe between A-phase stator windings and B-phase stator windings is included, so that A, B interphase insulation leakage current is as follows:
IAB＝I2-MI3
wherein N, M is A, C alternate lap penstocks and A, B alternate lap penstocks total number respectively, obtains A looks total leakage current from above and is:
IA＝IAB+IAC+I4。
the leakage current measurement value I of the A and B interphase single lapped water conduit3Comparing the measured value with a calculated theoretical value I' during the test, when I3And when the I 'does not exceed the set range, using the I' as the leakage current measured value of the single lapped water conduit between the phases A and B, wherein the insulation leakage current value between the phases A, C at the time is as follows:
IAC＝I1-NI′
A. the phase-to-phase insulation leakage current is as follows:
IAB＝I2-MI′
wherein N, M is A, C alternate lap penstocks and A, B alternate lap penstocks total number respectively, obtains A looks total leakage current from above and is:
IA＝IAB+IAC+I4＝I1+I2+I4-NI′-MI′
when I is3When the difference value is compared with I' and exceeds the set range, the pure water resistivity of the single lapped water conduit measured at the moment is checked, and when no error is confirmed, I is used3And (4) as a measured value of the leakage current of the single lapped water conduit between the phase A and the phase B, if an error exists, setting the actual pure water resistivity again, and recalculating and determining again.
The method for calculating the theoretical value I' of the leakage current of the single lap joint water conduit comprises the following steps:
the pure water conductivity of the water conduit is measured and recorded as sigma, the length L of the alternate single lapped water conduit is looked up or measured, the radius of the pure water conduit is r, the parameters are input into a computer 6, and the equivalent resistance of the single lapped water conduit is calculated as follows:
Figure BDA0003046978990000081
theoretical leakage of single lapped diversion pipe under set test high pressure UThe leakage current value is:
Figure BDA0003046978990000082

Claims (9)

1. the direct-current voltage resistance tester of the inter-phase lapped water diversion pipe for the internal water-cooled generator is characterized by comprising a control and signal processing box (1), a high-voltage generating device (2) and a signal collecting box (3), wherein the control and signal processing box (1) receives a power supply and controls the high-voltage generating device (2) to generate a set high voltage, the high-voltage generating device (2) feeds a current value back to the control and signal processing box (1) through a measuring terminal, a shielding end of the high-voltage generating device (2) is electrically connected with a water collecting pipe (4) and the signal collecting box (3), a high-voltage output end of the high-voltage generating device (2) is electrically connected with a stator winding (5) of a pressurized phase, the signal collecting box (3) is connected with the stator windings (5) of the other two non-pressurized phases through a first non-pressurized connecting cable (7) and a second non-pressurized connecting cable (8), and the end parts of the first non-pressurized connecting cable (7) and the second non-pressurized connecting cable (8) are provided with amperometers The non-pressurized phase stator winding penetrates through a pincerlike ammeter, a single lap joint water pipe connecting cable (9) on a signal acquisition box (3) is connected with the single lap joint water pipe, a first non-pressurized connecting cable (7), a second non-pressurized connecting cable (8) and the single lap joint water pipe connecting cable (9) are connected with a current measuring unit in the signal acquisition box (3), the signal acquisition box (3) sends measured current values to a control and signal processing box (1), the control and signal processing box (1) calculates the total leakage current of the lap joint water pipe through the measured leakage current of the single lap joint water pipe, and then calculates the total leakage current of the pressurized phase by combining the measured insulation leakage currents of all phases.
2. The direct-current withstand voltage tester for the internal water-cooled generator with interphase overlapping water conduits according to claim 1, wherein the signal collection box (3) is electrically connected with a ground resistance of the stator winding (5) of the pressurized phase, the ground resistance is a loop resistance formed by grounding of an iron core, and the signal collection box collects the leakage current of the pressurized phase to the ground and sends the value to the control and signal processing box (1).
3. The direct-current withstand voltage tester for the internal water-cooled generator with the inter-phase lapped water conduits as claimed in claim 2, wherein the shielding connection of the water collecting pipe (4) is provided with a pure water polarization potential compensation circuit (10).
4. The direct-current voltage resistance tester for the internal water-cooled generator with the interphase overlapping water conduit according to claim 3, characterized in that the control and signal processing box (1) is in communication connection with a computer (6).
5. The direct-current voltage resistance tester for the internal water-cooled generator with interphase overlapping water pipes according to claim 1, wherein the single overlapping water pipe connecting cable (9) is electrically connected with the single overlapping water pipe through a pincer-shaped ammeter, and the pincer-shaped ammeter measures the leakage current of the single overlapping water pipe and sends the value to the control and signal processing box (1).
6. The direct-current withstand voltage tester for the internal water-cooled generator with the inter-phase lapped water pipes according to claim 4, wherein the control and signal processing box (1) is internally provided with an intermediate frequency voltage doubling control circuit and a data processing unit, the intermediate frequency voltage doubling control circuit is internally provided with a PWM (pulse width modulation) circuit, the PWM circuit outputs signals to control an IGBT (insulated gate bipolar translator) device of the high-voltage generating device (2) to generate set high voltage, and the data processing unit receives voltage and current analog signals measured by the high-voltage generating device (2) and the signal acquisition box (3), converts the voltage and current analog signals into digital signals and transmits the digital signals to the computer (6).
7. The pressure test method of the direct current pressure tester of the internal water cooled generator using the interphase overlapping water conduit according to claim 6 is characterized in that the A-phase test comprises the following specific steps:
step one, the control and signal processing box (1) controls the high-pressure end of the high-pressure generating device (2) to be boosted to reach a set test high pressure, and the signal acquisition box (3) is connected with a single lap joint water conduit through a first non-pressurized connecting cable (7), a second non-pressurized connecting cable (8) and a single lap joint water conduitA and C phase leakage current value I under test voltage U is collected by a current measuring unit connected with a cable (9)1Leakage current values of A and B phases I2A and B interphase single lap joint water conduit leakage current measurement value I3And A relative earth leakage current value I4And transmitting the measured value to the computer (6);
step two, the computer (6) calculates the measured current value, and the A, C interphase insulation leakage current value is as follows:
IAC＝I1-NI3
A. the phase-to-phase insulation leakage current is as follows:
IAB＝I2-MI3
wherein N, M is A, C alternate lap penstocks and A, B alternate lap penstocks total number respectively, obtains A looks total leakage current from above and is:
IA＝IAB+IAC+I4。
8. the DC withstand voltage test method for the internal water-cooled generator with the interphase overlapping water conduit according to claim 7, wherein the leakage current measured value I of the interphase single overlapping water conduit A and the interphase single overlapping water conduit B3Comparing the measured value with a calculated theoretical value I' during the test, when I3And when the I 'does not exceed the set range, using the I' as the leakage current measured value of the single lapped water conduit between the phases A and B, wherein the insulation leakage current value between the phases A, C at the time is as follows:
IAC＝I1-NI′
A. the phase-to-phase insulation leakage current is as follows:
IAB＝I2-MI′
wherein N, M is A, C alternate lap penstocks and A, B alternate lap penstocks total number respectively, obtains A looks total leakage current from above and is:
IA＝IAB+IAC+I4＝I1+I2+I4-NI′-MI′
when I is3When the difference value of the I 'and the I' is compared to exceed the set range, the single lap joint measured at the moment is carried outChecking the resistivity of pure water in the water conduit, and using I when no error is found3And (4) as a measured value of the leakage current of the single lapped water conduit between the phase A and the phase B, if an error exists, setting the actual pure water resistivity again, and recalculating and determining again.
9. The direct-current withstand voltage test method for the internal water-cooled generator with the interphase overlapping water conduit according to claim 8, wherein the calculation method for the theoretical value I' of the leakage current of the single overlapping water conduit is as follows:
the pure water conductivity to the water conduit is surveyed, is marked as sigma, looks up the length L of alternate single overlap joint water conduit, and the pure water intraductal radius is r, inputs computer (6) with the parameter, and the equivalent resistance who calculates single overlap joint water conduit does:
Figure FDA0003046978980000031
under a set test high voltage U, the theoretical leakage current value of a single lapped water conduit is as follows:
Figure FDA0003046978980000032
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