CN210222121U - Insulation resistance tester for internal water-cooled generator - Google Patents
Insulation resistance tester for internal water-cooled generator Download PDFInfo
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- CN210222121U CN210222121U CN201920405863.5U CN201920405863U CN210222121U CN 210222121 U CN210222121 U CN 210222121U CN 201920405863 U CN201920405863 U CN 201920405863U CN 210222121 U CN210222121 U CN 210222121U
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Abstract
The utility model discloses a water internal cooling generator insulation resistance tester belongs to the engineering survey field. The tester includes: the device comprises a control operation unit, a high-voltage source, a high-voltage sampling unit, a water branch current shielding unit, a winding leakage current unit and a data acquisition unit, wherein the high-voltage source is respectively and electrically connected with the control operation unit and a stator winding of the water-cooled generator, the high-voltage sampling unit is electrically connected with the high-voltage source, the water branch current shielding unit is respectively and electrically connected with a water collecting pipe of the water-cooled generator and a base of the water-cooled generator so as to shield leakage current on a water branch and sample the leakage current on a water branch, the winding leakage current unit is electrically connected with the base so as to sample the leakage current on an insulation resistance branch, the data acquisition unit is respectively and electrically connected with the high-voltage sampling unit, the water branch current shielding unit and the winding leakage current unit, and the control operation unit is electrically connected with the data acquisition.
Description
Technical Field
The utility model relates to an engineering survey field, in particular to interior cold generator insulation resistance tester of water.
Background
At present, the cooling mode of a large-capacity generator is mainly stator water internal cooling. Specifically, a cooling water pipe is arranged in the middle of each stator winding of the generator and used for cooling the generator windings. Because the stator winding and the cooling water pipe are not electrically insulated in the generator, the stator winding is electrically connected with the ground by two parallel branches, one branch is a branch (water branch for short) of the stator winding which is grounded through an internal water cooling system (namely a machine base), and the other branch is a branch of the stator winding which is grounded.
The insulation resistance of the stator winding is the resistance of the stator winding to the ground branch. When the insulation resistance of the stator winding of the generator is measured by adopting the insulation resistance tester of the water-cooled generator, the leakage current on the water branch can influence the leakage current on the ground branch. For this purpose, the water collection pipe (a thick water pipe in which a plurality of cooling water pipes are collected) can be disconnected from the ground connection during measurement. After disconnection, see fig. 1, the water resistance (resistance of the water branch) is divided into two, including the water resistance R of the winding to the catchment pipeYAnd the water resistance R of the water collecting pipe to the machine baseH. The water collecting pipe can be connected to the shielding end G of the tester, and the water flowing through the water resistor R is absorbed by the shielding of the testerYLeakage current I of branchY. The tester generally adopts a low-voltage end shielding technology, namely the potential of a shielding end G is equal to that of a machine base E, so that a winding end L flows through a water resistor RHLeakage current I of branchHIs 0, thereby ensuring that the current flowing into the tester is only the current flowing through the insulation resistor RXWinding leakage current IXAnd calculating the winding insulation resistance R based on IXX。
In the process of implementing the present invention, the inventor finds that the prior art has at least the following problems: the output voltage of the tester has a serious drop phenomenon, and the requirement of insulation resistance measurement on the voltage can not be met after the output voltage drops, so that the accuracy of the insulation resistance measurement is influenced.
SUMMERY OF THE UTILITY MODEL
The embodiment of the utility model provides a cold generator insulation resistance tester in water can insulation resistance measuring accuracy. The technical scheme is as follows:
the utility model provides a cold generator insulation resistance tester in water, cold generator insulation resistance tester in water includes: a control operation unit, a high voltage source, a high voltage sampling unit, a water branch current shielding unit, a winding leakage current unit and a data acquisition unit,
the high-voltage source is respectively electrically connected with the control arithmetic unit and a stator winding of the water-cooled generator to apply voltage to the stator winding under the indication of the control arithmetic unit, the high-voltage sampling unit is electrically connected with the high-voltage source to sample the output voltage of the high-voltage source, the water branch current shielding unit is respectively electrically connected with a water collecting pipe of the water-cooled generator and a base of the water-cooled generator to shield the leakage current on a water branch and sample the leakage current on the water branch, the water branch is a branch of which the stator winding is grounded through a water-cooled system, the insulation resistance branch is a branch of which the stator winding is grounded through the base of the water-cooled generator, the water branch is connected with the insulation resistance branch in parallel, and the winding leakage current unit is electrically connected with the base to sample the leakage current on the insulation resistance branch, the data acquisition unit respectively with high pressure sampling unit water branch road current shielding unit with winding leakage current unit electricity is connected in order to right high pressure sampling unit's sampling signal water branch road current shielding unit's sampling signal and winding leakage current unit's sampling signal converts respectively, control arithmetic unit with the data acquisition unit electricity is connected in order to be based on after the data acquisition unit conversion high pressure sampling unit's sampling signal water branch road current shielding unit's sampling signal and winding leakage current unit's sampling signal confirms stator winding's insulation resistance.
Optionally, the water branch includes a winding catchment pipe branch and a catchment pipe base branch, the winding catchment pipe branch is a loop between the stator winding and the catchment pipe, the catchment pipe base branch is a loop between the catchment pipe and the base, the winding catchment pipe branch is connected in series with the catchment pipe base branch, the insulation resistance tester for the internal water-cooled generator further includes a polarization potential compensation unit, and the polarization potential compensation unit is electrically connected with the catchment pipe of the internal water-cooled generator and the base of the internal water-cooled generator respectively to compensate the polarization potential on the catchment pipe base branch under the instruction of the control operation unit.
Optionally, the polarization potential compensation unit comprises a voltmeter, a direct current power supply and a protection resistor,
one end of the voltmeter is electrically connected with one end of the direct-current power supply, the other end of the direct-current power supply is electrically connected with one end of the protection resistor, the other end of the protection resistor is electrically connected with the other end of the voltmeter, a connecting point of the voltmeter and the direct-current power supply is electrically connected with the base, a connecting point of the protection resistor and the voltmeter is electrically connected with the water collecting pipe, and the control operation unit is respectively electrically connected with the voltmeter and the direct-current power supply.
Optionally, the high pressure sampling unit comprises: a first resistance and a second resistance, wherein the first resistance and the second resistance are connected,
the first resistor and the second resistor are connected between the stator winding and the analog ground in series, and a connecting point of the first resistor and the second resistor is electrically connected with the data acquisition unit.
Optionally, the water branch current shielding unit includes: a current line, a voltage line, a first operational amplifier, a third resistor, and a fourth resistor,
the current line is electrically connected with one end of the voltage line and is electrically connected with the water collecting pipe,
the other end of the current line is electrically connected with the inverting input end of the first operational amplifier, the other end of the voltage line is electrically connected with the non-inverting input end of the first operational amplifier,
one end of the third resistor is electrically connected with the connection point of the voltage line and the first operational amplifier, the other end of the third resistor is electrically connected with the base,
one end of the fourth resistor is electrically connected with a connection point of the current line and the first operational amplifier, the other end of the fourth resistor is electrically connected with an output end of the first operational amplifier, and a connection point of the fourth resistor and the first operational amplifier is electrically connected with the data acquisition unit.
Optionally, the winding leakage current unit includes: a second operational amplifier, a first switch and a fifth resistor,
the non-inverting input end of the second operational amplifier is connected with an analog ground, the inverting input end of the second operational amplifier is electrically connected with the engine base, one end of the first switch is electrically connected with the connection point of the second operational amplifier and the engine base, the other end of the first switch is connected with one end of a fifth resistor in series, the other end of the fifth resistor is electrically connected with the output end of the second operational amplifier, and the output end of the second operational amplifier is electrically connected with the data acquisition unit.
Optionally, the winding leakage current unit further comprises a second switch and a sixth resistor,
one end of the first switch is electrically connected with one end of the second switch, the other end of the second switch is connected with one end of the sixth resistor in series, and the other end of the fifth resistor is electrically connected with the other end of the sixth resistor.
Optionally, the data acquisition unit comprises an analog-to-digital converter,
the analog-to-digital converter is respectively electrically connected with a connection point of the first resistor and the second resistor, a connection point of the fourth resistor and the first operational amplifier, an output end of the second operational amplifier and the control operational unit.
Optionally, the data acquisition unit further comprises a third switch, a fourth switch, and a fifth switch,
one end of the third switch is electrically connected with a connection point of the first resistor and the second resistor, one end of the fourth switch is electrically connected with a connection point of the fourth resistor and the first operational amplifier, one end of the fifth switch is electrically connected with an output end of the second operational amplifier, and the other ends of the third switch, the fourth switch and the fifth switch are electrically connected with the control operation unit through the analog-to-digital converter.
Optionally, the insulation resistance tester for the internal water-cooled generator further comprises a display screen, and the display screen is electrically connected with the control arithmetic unit.
The embodiment of the utility model provides a beneficial effect that technical scheme brought is: the leakage current on the water branch is sampled through the water branch current shielding unit, the control operation unit can determine the water resistance (the resistance of the water branch) based on the leakage current on the water branch, and the water resistance can reflect the measurement field working condition, for example, the output voltage of the tester is likely to drop when the water resistance is too low, so that whether the calculation of the insulation resistance is facilitated under the measurement field working condition can be evaluated based on the water resistance, the calculation of the insulation resistance is ensured to be performed under the reasonable working condition (for example, the output voltage drop amplitude of the tester is determined to be very small based on the water resistance), and thus, the measurement accuracy and the effectiveness of the insulation resistance are improved.
Drawings
In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the drawings needed to be used in the description of the embodiments will be briefly described below, and it is obvious that the drawings in the following description are only some embodiments of the present invention, and it is obvious for those skilled in the art to obtain other drawings without creative efforts.
Fig. 1 is a schematic structural diagram of a circuit model for testing insulation resistance of a water-cooled generator provided by the present invention;
fig. 2 is a block diagram of an insulation resistance tester for a water-cooled generator according to an embodiment of the present invention;
fig. 3 is a schematic structural diagram of a high-pressure sampling unit according to an embodiment of the present invention;
fig. 4 is a schematic structural diagram of a water branch current shielding unit according to an embodiment of the present invention;
fig. 5 is a schematic structural diagram of a winding leakage current unit provided in an embodiment of the present invention;
fig. 6 is a schematic structural diagram of a data acquisition unit provided in an embodiment of the present invention;
fig. 7 is a block diagram of an insulation resistance tester for a water-cooled generator according to an embodiment of the present invention;
fig. 8 is a schematic structural diagram of a polarization potential compensation unit according to an embodiment of the present invention.
In the drawing, 100 a water-cooled generator insulation resistance tester, 1 a control arithmetic unit, 2 a high voltage source, 3 a high voltage sampling unit, 4 a water branch current shielding unit, 5 a winding leakage current unit, 6 a data acquisition unit, a R31 first resistor, a R32 second resistor, 41 current lines, 42 voltage lines, a U43 first operational amplifier, a R44 third resistor, a R45 fourth resistor, a U51 second operational amplifier, a K52 first switch, a K53 second switch, a R54 fifth resistor, a R55 sixth resistor, a K61 third switch, a K62 fourth switch, a K63 fifth switch, a 64 analog-to-digital converter, a 7 display screen, an 8 polarization potential compensation unit, a V81 voltmeter, a U82 direct current power supply and an R83 protection resistor.
Detailed Description
In order to make the objects, technical solutions and advantages of the present invention clearer, embodiments of the present invention will be described in further detail below with reference to the accompanying drawings.
To facilitate understanding of the technical solutions provided by the embodiments of the present invention, the terms related to the embodiments of the present invention will be explained first.
The water collecting pipe refers to a thick water pipe formed by gathering a plurality of cooling water pipes.
And the water branch circuit is a branch circuit of which the designated sub-winding is grounded through the water internal cooling system. The water branch comprises a winding water catchment pipe branch and a water catchment pipe base sub-branch, and the winding water catchment pipe branch is connected with the water catchment pipe base sub-branch in series. The winding water collecting pipe branch is a loop between the stator winding and the water collecting pipe, and the water collecting pipe base sub-branch is a loop between the water collecting pipe and the base. Referring to fig. 1, L denotes a stator winding of the water cooled generator, G denotes a catchment pipe of the water cooled generator, and E denotes a housing of the water cooled generator. Equivalent water resistance in winding catchment pipe branch is RYThe water resistance of all stator winding water branches is equivalent to parallel connection; the equivalent water resistance in the sub-branch of the catchment pipe machine base is RHSpecifically a water inlet and a water outletThe sewage draining outlet and the excitation end water pipe are connected in parallel to the ground water resistance.
And the insulation resistance branch circuit is a branch circuit of which the appointed sub-winding is grounded through a base of the water-cooled generator. The water branch is connected with the insulation resistance branch in parallel. Referring to fig. 1, the equivalent resistance of the insulation resistance branch is RX。
Insulation resistance of stator winding, meaning resistance of insulation resistance branch, i.e. RX。
Fig. 2 shows an insulation resistance tester for a water-cooled generator provided by an embodiment of the present invention, which is suitable for measuring the insulation resistance of a stator winding of the water-cooled generator. Referring to fig. 2, the internal water-cooled generator insulation resistance tester 100 includes: the device comprises a control operation unit 1, a high-voltage source 2, a high-voltage sampling unit 3, a water branch current shielding unit 4, a winding leakage current unit 5 and a data acquisition unit 6.
The high voltage source 2 is respectively electrically connected with the control arithmetic unit 1 and the stator winding of the water-cooled generator, and is used for applying voltage to the stator winding of the water-cooled generator under the instruction of the control arithmetic unit 1.
The high voltage sampling unit 3 is electrically connected to the high voltage source 2 and is configured to sample an output voltage of the high voltage source 2.
The water branch current shielding unit 4 is respectively electrically connected with a water collecting pipe of the water-cooled generator and a base of the water-cooled generator, and is used for shielding leakage current on the water branch so as to prevent the leakage current on the water branch from flowing into the insulation resistance branch and sampling the leakage current on the water branch.
And the winding leakage current unit 5 is electrically connected with a base of the water-cooled generator and is used for sampling the leakage current of the stator winding.
The data acquisition unit 6 is electrically connected with the high-voltage sampling unit 3, the water branch current shielding unit 4 and the winding leakage current unit 5 respectively, and is used for converting the sampling signal of the high-voltage sampling unit 3, the sampling signal of the water branch current shielding unit 4 and the sampling signal of the winding leakage current unit 5 respectively. The conversion may be an analog to digital conversion.
The control operation unit 1 is electrically connected with the data acquisition unit 6 and is used for determining the insulation resistance of the stator winding based on the sampling signal of the high-voltage sampling unit 3, the sampling signal of the water branch current shielding unit 4 and the sampling signal of the winding leakage current unit 5 which are converted by the data acquisition unit 6.
The water branch is a branch of the stator winding which is grounded through the water internal cooling system. Referring to FIG. 1, the water branch is RYAnd RHA series of branches. RYRepresenting the water resistance of the stator winding to the header, RYThe water resistances of all the stator winding water branches are connected in parallel; rHRepresenting the water resistance of the catchment pipe to the foundation, RHThe water inlet, the water outlet, the sewage draining outlet and the excitation end water pipe are connected in parallel to ground water resistance; rXIs the insulation resistance of the stator winding of the generator.
The leakage current on the water branch is sampled through the water branch current shielding unit, the control operation unit can determine the water resistance (the resistance of the water branch) based on the leakage current on the water branch, and the water resistance can reflect the measurement field working condition, for example, the output voltage of the tester 100 is likely to drop when the water resistance is too low, so that whether the calculation of the insulation resistance is facilitated under the measurement field working condition can be evaluated based on the water resistance, the calculation of the insulation resistance is ensured to be performed under the reasonable working condition (for example, the drop amplitude of the output voltage of the tester 100 is determined to be very small based on the water resistance), and thus, the measurement accuracy and the effectiveness of the insulation resistance are improved.
An exemplary structure of each unit is described below.
Illustratively, high voltage source 2 implements the output of the high voltage of tester 100. Because the tester 100 has a large power, in this embodiment, the input of the high voltage source 2 may be AC220V, the output rated voltage may be 2500V, 5000V or 10000V, and the maximum output current may reach 150 mA. The start and stop of the high-voltage source 2 are controlled by the control arithmetic unit 1.
Illustratively, the high voltage sampling unit 3 implements a partial pressure sampling function in which the high voltage source 2 outputs a high voltage. Referring to fig. 3, the high voltage sampling unit 3 includes: a first resistor R31 and a second resistor R32. The first resistor R31 and the second resistor R32 are connected between the stator winding and the analog ground AGND in series, and the connection point of the first resistor R31 and the second resistor R32 is electrically connected with the data acquisition unit 6. The first resistor R31 and the second resistor R32 are voltage dividing resistors. Through R31 and R32, the high-voltage sampling of 2500 ~ 10000V is the voltage sampling signal of 0.5 ~ 2V, gives data acquisition unit 6 and digitizes the high-voltage sampling voltage.
Exemplarily, the water branch current shielding unit 4 realizes the water branch leakage current IYShielding absorption and measurement. Specifically, the water branch current shielding unit 4 is configured to sample a leakage current on the winding water collection pipe branch, and block the leakage current on the winding water collection pipe branch from flowing into the water collection pipe base sub-branch. Referring to fig. 4, the water branch current-shielding unit 4 includes: current line 41, voltage line 42, first operational amplifier U43, third resistor R44, and fourth resistor R45. One ends of the current line 41 and the voltage line 42 are electrically connected and a connection point of the current line 41 and the voltage line 42 is electrically connected to the water collecting pipe. The other end of current line 41 is electrically connected to the inverting input of first operational amplifier U43, and the other end of voltage line 42 is electrically connected to the non-inverting input of first operational amplifier U43. One end of the third resistor R44 is electrically connected to the connection point of the voltage line 42 and the first operational amplifier U43, and the other end of the third resistor R44 is electrically connected to the base. One end of the fourth resistor R45 is electrically connected to the connection point of the current line 41 and the first operational amplifier U43, the other end of the fourth resistor R45 is electrically connected to the output end of the first operational amplifier U43, and the connection point of the fourth resistor R45 and the first operational amplifier U43 is electrically connected to the data acquisition unit 6.
Illustratively, the resistance value of the third resistor R44 is not lower than 1M Ω, so that the shielding voltage line 42 exhibits a high-resistance characteristic. The fourth resistor R45 is connected between the output terminal and the inverting input terminal of the first operational amplifier U43 to form negative feedback, and is connected to the shielding current line 41. The fourth resistor R45 has a resistance value not higher than 1k Ω, so that the shielding current line 41 exhibits a low resistance characteristic. Water branch leakage current IYThe shielding current line 41 with low resistance characteristic flows from the end of the water collecting pipe G, and flows through the fourth resistor R45 to generate a voltage V2, and then the voltage V is sent to the data acquisition unit 6 to be digitalized. The first operational amplifier U43 is a precision operational amplifier, which has high input impedance (not less than 1M omega) to ensure the leakage current of water branchThe shielding current line 41 flows in, and on the other hand, the shielding current line 41 has a low offset voltage (the low offset voltage is formed by the shielding voltage line 42 at the two input ends of the first operational amplifier U43 and the shielding current line 41 being shorted and connected to the base (ground) through the third resistor R44), so that the voltage of the water collecting pipe G is equal to the potential of the base E, i.e., VGEWhen it is 0, I can be ensuredH0, thereby ensuring that the current flowing into the E end of the instrument is only the leakage current I of the stator windingX。
Exemplarily, the winding leakage current unit 5 realizes the winding leakage current IXThe measurement function of (2). Referring to fig. 5, the winding leakage current unit 55 includes: the circuit comprises a second operational amplifier U51, a first switch K52, a second switch K53, a fifth resistor R54 and a sixth resistor R55.
The non-inverting input terminal of the second operational amplifier U51 is connected to the analog ground AGND, and the inverting input terminal of the second operational amplifier U51 is electrically connected to the base.
One end of the first switch K52 and one end of the second switch K53 are electrically connected and are electrically connected with the connection point of the second operational amplifier U51 and the base, the other end of the first switch K52 is connected in series with one end of the fifth resistor R54, the other end of the second switch K53 is connected in series with one end of the sixth resistor R55, the other ends of the fifth resistor R54 and the sixth resistor R55 are connected and the connection point of the fifth resistor R54 and the sixth resistor R55 is electrically connected with the output end of the second operational amplifier U51, and the output end of the second operational amplifier U51 is electrically connected with the data acquisition unit 6.
Wherein, the closing and opening of the first switch K52 and the second switch K53 are respectively controlled by the control arithmetic unit 1. The control arithmetic unit 1 is also used for controlling the first switch K52 to be closed and the second switch K53 to be opened or controlling the first switch K52 to be opened and the second switch K53 to be closed. The first switch K52 and the second switch K53 are respectively conducted, so that leakage current I of stator windings with different sizes is realizedXThe voltage signal V3 is obtained by I-V conversion and then sent to the data acquisition unit 6 to be digitalized. Leakage current I due to stator windingXHas a maximum size of 106The span range, the range of single resistance can not satisfy this span range, consequently, the embodiment of the utility model provides a set up the different resistance of two resistances and measure. Specifically, the firstThe values of the fifth resistor R54 and the sixth resistor R55 are different, and the resistance value of the fifth resistor R54 is smaller than that of the sixth resistor R55. The sixth resistor R55 may be used to measure leakage currents below microamperes and the fifth resistor R54 may be used to measure leakage currents from microamperes to milliamperes. In measuring leakage current I of stator windingXIn the process, the control arithmetic unit 1 firstly closes the first switch K52 and opens the second switch K53, i.e. the fifth resistor R54 (small resistor) is used for measurement. When the voltage signal V3 is greater than the target voltage, the control arithmetic unit 1 keeps the first switch K52 closed and the second switch K53 open, performing the subsequent determination of the insulation resistance; when the voltage signal V3 is smaller than the target voltage, the control unit 1 opens the first switch K52 and closes the second switch K53, i.e. a sixth resistor R55 (large resistor) is used for measurement, so as to increase the amplitude of the voltage signal V3.
The data acquisition unit 6 illustratively effects the digitization of the sampled and converted voltages. Referring to fig. 6, the data acquisition unit 66 includes third to fifth switches K61, K62, K63, and an analog-to-digital converter (ADC) 64.
One end of the third switch k61 is electrically connected to the connection point of the first resistor R31 and the second resistor R32.
One end of the fourth switch k62 is electrically connected to the connection point of the fourth resistor R45 and the first operational amplifier U43.
One end of the fifth switch k63 is electrically connected to the output end of the second operational amplifier U51.
The other ends of the third switch k61, the fourth switch k62 and the fifth switch k63 are electrically connected to the control arithmetic unit 1 through the analog-to-digital converter 64.
The analog-to-digital converter 64 is configured to convert an electrical signal from a connection point of the first resistor R31 and the second resistor R32 into a first voltage signal, convert an electrical signal from a connection point of the fourth resistor R45 and the first operational amplifier U43 into a second voltage signal, and convert an electrical signal from an output terminal of the second operational amplifier U51 into a third voltage signal.
Wherein the third to fifth switches K61, K62, K63 are respectively controlled to be closed and opened by the control arithmetic unit 1. Since the data acquisition unit 6 can process only one signal at a time, only one of the third to fifth switches K61, K62, K63 can be closed during the same time period, and based on this, the control arithmetic unit 1 sequentially closes one of the third to fifth switches K61, K62, K63 at intervals.
Illustratively, the control arithmetic unit 1 implements functions of controlling the whole system, calculating measurement parameters, judging abnormal conditions, displaying the measurement parameters and prompt characters, and the like. The control operation unit 1 is used for determining the output voltage of the high-voltage source based on the converted sampling signal of the high-voltage sampling unit; determining water resistance on the water branch based on the converted sampling signal of the water branch current shielding unit and the output voltage of the high voltage source; and when the water resistance on the water branch is in a first target range, determining the insulation resistance of the stator winding based on the sampling signal of the winding leakage current unit and the output voltage of the high-voltage source.
Exemplarily, the control arithmetic unit 1 calculates the output voltage of the high voltage source 2 based on the first voltage signal, the first resistor R31, and the second resistor R32; calculating the leakage current on the water branch circuit based on the second voltage signal and the fourth resistor R45; calculating the water resistance on the water branch circuit based on the output voltage of the high voltage source 2 and the leakage current on the water branch circuit; and when the water resistance on the water branch is in the first target range, calculating the insulation resistance of the stator winding based on the third voltage signal.
Specifically, assuming that the first voltage signal is V1, the second voltage signal is V2, the third voltage signal is V3, and the output voltage of the high voltage source 2 is V0, V0 is (V1/R32) × (R31+ R32). Leakage current I on water branchYWater resistance R on water branch line V2/R45Y＝V0/IY. Leakage current I of stator windingXInsulation resistance R of stator winding V3/R54 or V3/R55X＝V0/IX。
Alternatively, the insulation resistance of the stator winding may be measured several times in a certain period by the tester 100, and the absorption ratio and the polarization index of the generator may be calculated from the insulation resistance of the stator winding several times. Illustratively, assume that tester 100 measures the insulation of the stator windings at 15S, 60S, and 600S, respectivelyResistance R15s、R60sAnd R600sThen, the absorption ratio is R60s/R15sPolarization index ═ R600s/R60s。
Referring to fig. 1, the insulation resistance tester 100 for the internal water-cooled generator further includes a display screen 7, and the display screen 7 is electrically connected to the control and operation unit 1.
Further, when the load is too heavy, the accuracy of measuring the insulation resistance of the stator winding by the tester 100 is not high. The water branch resistor R can be used for considering the overweight of the loadYCan be evaluated, therefore, by RYTo determine whether the load is too heavy. When the load is not heavy, the insulation resistance is calculated, and the accuracy of the insulation resistance can be improved. Based on this, the control arithmetic unit 1 is used for calculating the leakage current of the stator winding based on the third voltage signal when the water resistance on the water branch is in the first target range; the third voltage signal is calculated based on the output voltage of the high voltage source 2 and the leakage current of the stator winding to calculate the insulation resistance of the stator winding.
Illustratively, the first target range may be ≧ 50k Ω. The embodiment of the utility model provides a do not restrict the value of first target scope, in other embodiments, also can set up the first target scope that needs according to measuring historical experience value.
The control arithmetic unit 1 is also used for switching off the voltage source when the water resistance of the water branch is not in the first target range and is lower than the target water resistance. When the water resistance on the water branch is below the target water resistance, meaning the load is too heavy, then actively shutting off the high pressure will protect the tester 100 from damage due to overload. Optionally, the control arithmetic unit 1 is further configured to output an overload prompt to the display 7. The field personnel can investigate field problems according to the overweight prompt of the load displayed by the display screen 7, adjust the working condition and facilitate the field test of the insulation resistor of the generator.
Further, when the output voltage drop degree of the tester 100 is large, the accuracy of the insulation resistance measured by the tester 100 is not high. Based on this, the control arithmetic unit 1 is configured to determine the water resistance on the water branch based on the converted sampling signal of the water branch current shielding unit and the output voltage of the high voltage source when the output voltage of the high voltage source 2 is in the second target range.
Specifically, the control arithmetic unit 1 is configured to calculate a leakage current on the water branch based on the second voltage signal and the fourth resistor R45 when the output voltage of the high voltage source 2 is in the second target range; and then based on the output voltage of the high voltage source 2 and the leakage current on the water branch, calculating the water resistance on the water branch.
The second target range may be a nominal voltage of 85% to 90% of the nominal voltage output by the tester 100. The embodiment of the utility model provides a do not restrict the value of second target scope, in other implementation modes, also can require to set up the second target scope that needs according to relevant standard.
Exemplarily, the control arithmetic unit 1 is further configured to determine the insulation resistance of the stator winding based on the sampling signal of the winding leakage current unit and the output voltage of the high voltage source when the output voltage of the high voltage source 2 is the fourth target range. The fourth target range may be from the nominal voltage of the tester 100 output by 90% to the nominal voltage. That is, when the output voltage of the high voltage source 2 falls within the rated voltage of 90% -the rated voltage output by the tester 100, the test condition is considered to be normal, and the insulation resistance is directly calculated without calculating the water resistance. When the output voltage of the high voltage source 2 is in the fifth target range, the control operation unit 1 outputs a voltage drop prompt to the display screen 7. The fifth target range may be 85% and below the nominal voltage output by the tester 100. The field personnel can confirm the validity of the insulation resistance test according to the voltage drop prompt displayed by the display screen 7, check the field problems, adjust the working condition and facilitate the field test of the insulation resistance of the generator.
Illustratively, the control arithmetic unit 1 is further configured to output an insulation resistance abnormality prompt message to the display 7 when the insulation resistance of the stator winding is within the third target range.
Wherein the third target range may be ≦ 10M Ω. The embodiment of the utility model provides a do not restrict the value of third target scope, in other embodiments, also can set up the third target scope that needs according to measuring historical experience value. By outputting the abnormal prompt information of the insulation resistance to the display screen, field personnel can know that the measured value of the insulation resistance is abnormal. On-site personnel can investigate on-site problems according to the prompt of the instrument, adjust the working condition and greatly facilitate the on-site test of the insulation resistance of the generator.
As mentioned above, the voltage of the water manifold base sub-branch can be controlled to be 0 by the water branch current shielding unit 4. However, in practice, when measuring the insulation resistance in situ, a disturbing polarization potential E often occurs between the collector and the machine baseH(see fig. 7), which is mainly a direct current voltage, the amplitude is from tens of mV to hundreds of mV, the polarity is sometimes positive (the water catchment pipe is at a positive potential relative to the machine base) and sometimes negative (the water catchment pipe is at a negative potential relative to the machine base), so that the potential between the water catchment pipe and the machine base is unequal, thereby affecting the insulation resistance measurement. Based on this, the insulation resistance tester 100 for the water-cooled generator further comprises a polarization potential compensation unit 8, the polarization potential compensation unit 8 is respectively electrically connected with the water collecting pipe of the water-cooled generator and the base of the water-cooled generator, and the polarization potential compensation unit 8 is used for compensating the polarization potential on the sub-branch of the base of the water collecting pipe under the indication of the control operation unit 1 so as to ensure that the voltage of the sub-branch of the base of the water collecting pipe is 0.
Fig. 8 shows an exemplary structure of the polarization potential compensation unit. Referring to fig. 8, the polarization potential compensation unit 8 includes a voltmeter V81, a direct current power supply U82, and a protection resistor R83. One end of a voltmeter V81 is electrically connected with one end of a direct-current power supply U82, the other end of the direct-current power supply U82 is electrically connected with one end of a protection resistor R83, the other end of the protection resistor R83 is electrically connected with the other end of a voltmeter V81, a connecting point of the voltmeter V81 and the direct-current power supply U82 is electrically connected with a machine base, a connecting point of the protection resistor R83 and a connecting point of a voltmeter V81 are electrically connected with a water collecting pipe, and the control operation unit 1 is electrically connected with the voltmeter V81 and the direct-current power supply U82 respectively.
The principle of operation of the polarization potential compensation unit 8 is as follows: before the control arithmetic unit 1 starts the high voltage source 1 to output high voltage, firstly the voltmeter V81 is controlled to measure the voltage and the polarity between the water collecting pipe and the base, and then the direct current power supply U82 is controlled to output a voltage with the same magnitude and the opposite polarity to the water collecting pipe base branch to compensate the polarization potential. After compensation, the voltmeter V81 retests the voltage of the base sub-branch of the water collecting pipe, if the voltage is not 0, the output voltage of the direct current power supply U82 is continuously adjusted until the measured value of the voltmeter V81 is 0. At this time, the output voltage of the dc power supply U82 is maintained, and the control arithmetic unit 1 restarts the high voltage source 1 to output a high voltage, thereby measuring the insulation resistance. Illustratively, the polarization potential compensation range can reach +/-1V so as to meet the field anti-interference requirement. Wherein if the polarization potential measured in situ exceeds the range, the polarization potential can be indicated to be out of range by words on the display screen.
The above description is only for the preferred embodiment of the present invention, and is not intended to limit the present invention, and any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present invention should be included within the protection scope of the present invention.
Claims (10)
1. The utility model provides a cold generator insulation resistance tester in water which characterized in that, cold generator insulation resistance tester in water includes: a control operation unit, a high voltage source, a high voltage sampling unit, a water branch current shielding unit, a winding leakage current unit and a data acquisition unit,
the high-voltage source is respectively electrically connected with the control arithmetic unit and a stator winding of the water-cooled generator to apply voltage to the stator winding under the indication of the control arithmetic unit, the high-voltage sampling unit is electrically connected with the high-voltage source to sample the output voltage of the high-voltage source, the water branch current shielding unit is respectively electrically connected with a water collecting pipe of the water-cooled generator and a base of the water-cooled generator to shield the leakage current on a water branch and sample the leakage current on the water branch, the water branch is a branch of which the stator winding is grounded through a water-cooled system, the insulation resistance branch is a branch of which the stator winding is grounded through the base of the water-cooled generator, the water branch is connected with the insulation resistance branch in parallel, and the winding leakage current unit is electrically connected with the base to sample the leakage current on the insulation resistance branch, the data acquisition unit respectively with high pressure sampling unit water branch road current shielding unit with winding leakage current unit electricity is connected in order to right high pressure sampling unit's sampling signal water branch road current shielding unit's sampling signal and winding leakage current unit's sampling signal converts respectively, control arithmetic unit with the data acquisition unit electricity is connected in order to be based on after the data acquisition unit conversion high pressure sampling unit's sampling signal water branch road current shielding unit's sampling signal and winding leakage current unit's sampling signal confirms stator winding's insulation resistance.
2. The insulation resistance tester for the internal water-cooled generator according to claim 1, wherein the water branch comprises a winding water collection pipe branch and a water collection pipe base branch, the winding water collection pipe branch is a loop between the stator winding and a water collection pipe, the water collection pipe base branch is a loop between the water collection pipe and the base, the winding water collection pipe branch and the water collection pipe base branch are connected in series, and the insulation resistance tester for the internal water-cooled generator further comprises a polarization potential compensation unit, the polarization potential compensation unit is electrically connected with the water collection pipe of the internal water-cooled generator and the base of the internal water-cooled generator respectively so as to compensate the polarization potential on the water collection pipe base branch under the instruction of the control and operation unit.
3. The insulation resistance tester of the internal water cooled generator according to claim 2, wherein the polarization potential compensation unit comprises a voltmeter, a direct current power supply and a protection resistor,
one end of the voltmeter is electrically connected with one end of the direct-current power supply, the other end of the direct-current power supply is electrically connected with one end of the protection resistor, the other end of the protection resistor is electrically connected with the other end of the voltmeter, a connecting point of the voltmeter and the direct-current power supply is electrically connected with the base, a connecting point of the protection resistor and the voltmeter is electrically connected with the water collecting pipe, and the control operation unit is respectively electrically connected with the voltmeter and the direct-current power supply.
4. The insulation resistance tester for the internal water cooled generator according to any one of claims 1 to 3, wherein the high voltage sampling unit comprises: a first resistance and a second resistance, wherein the first resistance and the second resistance are connected,
the first resistor and the second resistor are connected between the stator winding and the analog ground in series, and a connecting point of the first resistor and the second resistor is electrically connected with the data acquisition unit.
5. The insulation resistance tester for the internal water cooled generator according to claim 4, wherein the water branch current shielding unit comprises: a current line, a voltage line, a first operational amplifier, a third resistor, and a fourth resistor,
the current line is electrically connected with one end of the voltage line and is electrically connected with the water collecting pipe,
the other end of the current line is electrically connected with the inverting input end of the first operational amplifier, the other end of the voltage line is electrically connected with the non-inverting input end of the first operational amplifier,
one end of the third resistor is electrically connected with the connection point of the voltage line and the first operational amplifier, the other end of the third resistor is electrically connected with the base,
one end of the fourth resistor is electrically connected with a connection point of the current line and the first operational amplifier, the other end of the fourth resistor is electrically connected with an output end of the first operational amplifier, and a connection point of the fourth resistor and the first operational amplifier is electrically connected with the data acquisition unit.
6. The insulation resistance tester for the internal water cooled generator according to claim 5, wherein the winding leakage current unit comprises: a second operational amplifier, a first switch and a fifth resistor,
the non-inverting input end of the second operational amplifier is connected with an analog ground, the inverting input end of the second operational amplifier is electrically connected with the engine base, one end of the first switch is electrically connected with the connection point of the second operational amplifier and the engine base, the other end of the first switch is connected with one end of a fifth resistor in series, the other end of the fifth resistor is electrically connected with the output end of the second operational amplifier, and the output end of the second operational amplifier is electrically connected with the data acquisition unit.
7. The insulation resistance tester for the internal water cooled generator according to claim 6, wherein the winding leakage current unit further comprises a second switch and a sixth resistor,
one end of the first switch is electrically connected with one end of the second switch, the other end of the second switch is connected with one end of the sixth resistor in series, and the other end of the fifth resistor is electrically connected with the other end of the sixth resistor.
8. The insulation resistance tester for the internal water cooled generator according to claim 7, wherein the data acquisition unit comprises an analog-to-digital converter,
the analog-to-digital converter is respectively electrically connected with a connection point of the first resistor and the second resistor, a connection point of the fourth resistor and the first operational amplifier, an output end of the second operational amplifier and the control operational unit.
9. The insulation resistance tester for the internal water cooled generator according to claim 8, wherein the data acquisition unit further comprises a third switch, a fourth switch, and a fifth switch,
one end of the third switch is electrically connected with a connection point of the first resistor and the second resistor, one end of the fourth switch is electrically connected with a connection point of the fourth resistor and the first operational amplifier, one end of the fifth switch is electrically connected with an output end of the second operational amplifier, and the other ends of the third switch, the fourth switch and the fifth switch are electrically connected with the control operation unit through the analog-to-digital converter.
10. The insulation resistance tester for the internal water-cooled generator according to any one of claims 1 to 3, further comprising a display screen, wherein the display screen is electrically connected with the control arithmetic unit.
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201920405863.5U CN210222121U (en) | 2019-03-27 | 2019-03-27 | Insulation resistance tester for internal water-cooled generator |
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| Application Number | Priority Date | Filing Date | Title |
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| CN201920405863.5U CN210222121U (en) | 2019-03-27 | 2019-03-27 | Insulation resistance tester for internal water-cooled generator |
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Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN110031678A (en) * | 2019-03-27 | 2019-07-19 | 武汉市康达电气有限公司 | Water-cooled generator Insulation Resistance Tester |
| CN111948455A (en) * | 2020-07-03 | 2020-11-17 | 中广核核电运营有限公司 | Insulation resistance detection device and method of generator and generator |
| CN113030795A (en) * | 2021-03-15 | 2021-06-25 | 中国大唐集团科学技术研究院有限公司华中电力试验研究院 | Pre-detection device and method before insulation test of stator winding of internal water-cooled generator |
-
2019
- 2019-03-27 CN CN201920405863.5U patent/CN210222121U/en active Active
Cited By (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN110031678A (en) * | 2019-03-27 | 2019-07-19 | 武汉市康达电气有限公司 | Water-cooled generator Insulation Resistance Tester |
| CN111948455A (en) * | 2020-07-03 | 2020-11-17 | 中广核核电运营有限公司 | Insulation resistance detection device and method of generator and generator |
| CN111948455B (en) * | 2020-07-03 | 2023-11-14 | 中广核核电运营有限公司 | Insulation resistance detection device and method of generator and generator |
| CN113030795A (en) * | 2021-03-15 | 2021-06-25 | 中国大唐集团科学技术研究院有限公司华中电力试验研究院 | Pre-detection device and method before insulation test of stator winding of internal water-cooled generator |
| CN113030795B (en) * | 2021-03-15 | 2023-04-14 | 中国大唐集团科学技术研究院有限公司华中电力试验研究院 | Pre-detection device and method before insulation test of stator winding of internal water-cooled generator |
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