Insulation resistance testing method and device for water-cooled generator with fixed grounding of manifold

Abstract

The present invention provides a method and device for testing the insulation resistance of a water-cooled generator with a fixedly grounded water manifold, which belongs to the field of engineering measurement. The method includes: adjusting the cooling water in the water-cooled generator to a first conductivity; when the cooling water is the first conductivity, measuring the first resistance value of the insulation resistance and the water resistance in the water-cooled generator in parallel, the insulation resistance is the resistance of the insulation branch, the water resistance is the resistance of the water branch, the water branch is connected in parallel with the insulation branch, and the insulation branch is the branch where the stator winding in the water-cooled generator is grounded through the base of the water-cooled generator; adjusting the cooling water in the water-cooled generator to a second conductivity; when the cooling water is the second conductivity, measuring the second resistance value of the insulation resistance and the water resistance in the water-cooled generator in parallel; based on the first conductivity, the first resistance value, the second conductivity and the second resistance value, determining the resistance value of the insulation resistance.

Description

Technical Field

[0001] The present invention relates to the field of engineering measurement, and in particular to a method and a device for testing the insulation resistance of a water-cooled generator with a fixedly grounded water collector. Background Art

[0002] At present, the cooling method of large-capacity generators is mainly stator water cooling, which is also called water-cooled generator. There is a cooling water pipe in the middle of each stator winding of the water-cooled generator to cool the generator winding. Since the stator winding and the cooling water pipe are not electrically insulated inside the generator, the electrical connection of the stator winding to the ground has two parallel branches, one is the branch where the stator winding is grounded (i.e., the frame) through the water-cooled system (referred to as the water branch), and the other is the stator winding to the ground branch (referred to as the insulation branch).

[0003] The insulation resistance of the stator winding is the resistance of the stator winding to the ground branch. When using a water-cooled generator insulation resistance tester to measure the insulation resistance of the stator winding of the generator, the leakage current on the water branch will affect the leakage current on the ground branch. For this reason, the water conduit (referring to the thick water pipe where multiple cooling water pipes converge) can be disconnected from the ground connection during measurement. After disconnection, refer to Figure 1 , the water resistance (resistance of the water branch) is divided into two parts, including the water resistance R Y , and the water resistance R of the water pipe to the machine base H The water collection pipe can be connected to the shielding terminal G of the tester, and the water flowing through the water resistance R is absorbed by the instrument shielding. Y Branch leakage current I Y The tester generally adopts low-voltage end shielding technology, that is, the potential of the shielding end G is equal to the potential of the base E, so that the winding end L flows through the water resistance R H Branch leakage current I H is 0, thus ensuring that the current flowing into the tester only flows through the insulation resistance R X Winding leakage current I X , and based on I X Calculate the winding insulation resistance R X .

[0004] However, when measuring certain generator sets, it is sometimes encountered that the ground connection on the header cannot be disconnected, thereby making it impossible to correctly measure the insulation resistance value using the above method. Summary of the invention

[0005] The embodiment of the present disclosure provides a method and device for testing the insulation resistance of a water-cooled generator with a fixed grounding manifold. The technical solution is as follows:

[0006] On the one hand, a method for testing the insulation resistance of a water-cooled generator with a fixedly grounded water manifold is provided, the method comprising:

[0007] adjusting cooling water in the water-cooled generator to a first conductivity;

[0008] When the cooling water has a first conductivity, measuring a first resistance value of an insulation resistance and a water resistance in the water-cooled generator connected in parallel, wherein the insulation resistance is the resistance of an insulation branch, the water resistance is the resistance of a water branch, the water branch is connected in parallel with the insulation branch, and the insulation branch is a branch for grounding a stator winding in the water-cooled generator through a frame of the water-cooled generator;

[0009] adjusting the cooling water in the water-cooled generator to a second conductivity;

[0010] When the cooling water has a second conductivity, measuring a second resistance value of an insulation resistance and a water resistance in the water-cooled generator connected in parallel;

[0011] The resistance value of the insulation resistor is determined based on the first conductivity, the first resistance, the second conductivity, and the second resistance.

[0012] Exemplarily, adjusting the cooling water in the water-cooled generator to a first conductivity includes:

[0013] Based on the correspondence between conductivity and pH value, determining the pH value corresponding to the first conductivity;

[0014] By controlling the flow rate of desalted water in the cooling water, the pH value of the cooling water is controlled to be the pH value corresponding to the first conductivity;

[0015] Alternatively, the step of adjusting the cooling water in the water-cooled generator to a first conductivity includes:

[0016] Controlling the pH value of the cooling water by controlling the flow rate of desalted water in the cooling water;

[0017] Based on the correspondence between conductivity and pH value, it is determined that the conductivity corresponding to the pH value of the cooling water is the first conductivity.

[0018] Exemplarily, the measuring of a first resistance value of an insulation resistor and a water resistor in the water-cooled generator connected in parallel includes:

[0019] Sampling an output voltage of a high voltage source, wherein the high voltage source is used to supply power to the water-cooled generator;

[0020] Measuring the leakage current of the water-cooled generator;

[0021] The first resistance value is calculated according to the sampled output voltage and the measured leakage current.

[0022] Exemplarily, determining the resistance of the insulation resistor based on the first conductivity, the first resistance, the second conductivity, and the second resistance includes:

[0023] The insulation resistance is calculated according to the following formula:

[0024]

[0025] Among them, R X is the insulation resistance, R M1 is the first resistance value, R M2 is the first resistance value, σ 1 is the first conductivity, σ 2 is the second electrical conductivity.

[0026] Exemplarily, the first conductivity is greater than the second conductivity, and a ratio of a difference between the first conductivity and the second conductivity to the first conductivity is greater than 1 / 2.

[0027] On the other hand, a device for testing the insulation resistance of a water-cooled generator with a fixedly grounded water manifold is provided, the device comprising:

[0028] A high voltage source connected to the water-cooled generator and used to apply voltage to the stator winding of the water-cooled generator;

[0029] a resistance detection module, connected to the water-cooled generator and the high-voltage source, respectively, and used for measuring a first resistance value of the insulation resistance and the water resistance in the water-cooled generator in parallel when the cooling water in the water-cooled generator has a first conductivity, the insulation resistance being the resistance of the insulation branch, the water resistance being the resistance of the water branch, the water branch being connected in parallel with the insulation branch, the insulation branch being a branch for grounding the stator winding in the water-cooled generator through the base of the water-cooled generator; and measuring a second resistance value of the insulation resistance and the water resistance in the water-cooled generator in parallel when the cooling water has a second conductivity;

[0030] The control operation module is connected to the resistance detection module, and is used to determine the resistance value of the insulation resistance based on the first conductivity, the first resistance value, the second conductivity and the second resistance value.

[0031] Exemplarily, the resistance detection module includes:

[0032] A high voltage sampling unit, connected to the high voltage source, and used to sample the output voltage of the high voltage source;

[0033] A winding leakage current measuring unit, connected to the water-cooled generator, for measuring the leakage current of the water-cooled generator;

[0034] The operation unit is connected to the high voltage sampling unit, the winding leakage current measuring unit and the control operation module respectively, and is used to calculate the first resistance value according to the sampled output voltage and the measured leakage current.

[0035] Exemplarily, the control operation module is used to calculate the resistance value of the insulation resistance according to the following formula:

[0036]

[0037] Among them, R X is the insulation resistance, R M1 is the first resistance value, R M2 is the first resistance value, σ 1 is the first conductivity, σ 2 is the second conductivity.

[0038] Exemplarily, the first conductivity is greater than the second conductivity, and a ratio of a difference between the first conductivity and the second conductivity to the first conductivity is greater than 1 / 2.

[0039] Exemplarily, the control operation module is connected to the high voltage source and is also used to output control instructions to the high voltage source, wherein the control instructions are used to control the high voltage source to apply voltage to the stator winding of the water-cooled generator.

[0040] The technical solution provided by the embodiments of the present disclosure has the following beneficial effects:

[0041] By changing the conductivity of the cooling water, the resistance of the water branch is changed. When the insulation branch resistance remains unchanged, the insulation resistance and the water resistance are measured in parallel under different conductivities. Based on the two conductivities and the corresponding parallel resistance, the insulation resistance value can be determined. This solution can test the insulation resistance of the water-cooled generator without disconnecting the ground connection on the water manifold, ensuring that the insulation resistance value can be measured without disconnecting the ground connection on the water manifold. BRIEF DESCRIPTION OF THE DRAWINGS

[0042] In order to more clearly illustrate the technical solutions in the embodiments of the present disclosure, the drawings required for use in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present disclosure. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0043] Figure 1 It is a schematic diagram of a water-cooled generator insulation resistance test circuit in the related art;

[0044] Figure 2 It is a schematic diagram of a water-cooled generator insulation resistance test circuit in the related art;

[0045] Figure 3 It is a flow chart of a method for testing the insulation resistance of a water-cooled generator with a fixedly grounded water manifold provided by an embodiment of the present disclosure;

[0046] Figure 4 It is a flow chart of a method for testing the insulation resistance of a water-cooled generator with a fixedly grounded water manifold provided by an embodiment of the present disclosure;

[0047] Figure 5 It is a structural schematic diagram of an insulation resistance test device for a water-cooled generator with a fixedly grounded water manifold provided by an embodiment of the present disclosure;

[0048] Figure 6 is a circuit diagram of a high voltage sampling unit provided by an embodiment of the present disclosure;

[0049] Figure 7 is a circuit diagram of a winding leakage current measuring unit provided in an embodiment of the present disclosure. DETAILED DESCRIPTION

[0050] In order to make the objectives, technical solutions and advantages of the present disclosure more clear, the embodiments of the present disclosure will be further described in detail below with reference to the accompanying drawings.

[0051] To facilitate understanding of the technical solution provided by the embodiment of the present invention, the terms involved in the embodiment of the present invention are first explained.

[0052] A water collector refers to a thick water pipe where multiple cooling water pipes converge.

[0053] Water branch refers to the branch where the stator winding is grounded through the water cooling system. The water branch includes the winding manifold sub-branch and the manifold machine base sub-branch, which are connected in series. The winding manifold sub-branch is the loop between the stator winding and the manifold, and the manifold machine base sub-branch is the loop between the manifold and the machine base. See Figure 1 , L represents the stator winding of the water-cooled generator, G represents the water collector of the water-cooled generator, and E represents the base of the water-cooled generator. The equivalent water resistance in the winding collector branch is R Y , which is equivalent to the water resistance of all stator winding water branches connected in parallel; the equivalent water resistance in the water collector base branch is R H , specifically the parallel connection of the water inlet, water outlet, sewage outlet and the excitation end water pipe to the ground water resistance.

[0054] Insulated branch refers to the branch where the sub-winding is grounded through the frame of the water-cooled generator. The water branch is connected in parallel with the insulating branch. Figure 1 , the equivalent resistance on the insulating branch is R X .

[0055] During the test, the water header is generally connected to the shielding end of the water-cooled generator insulation resistance tester, so that the potential of the G end of the water header is equal to that of the E end of the base by means of the equipotential shielding technology inside the instrument, so that the current flowing through R H The current I H =0. At this time, the current flowing into the water-cooled generator insulation resistance tester through the E terminal is only the current flowing through R X The current I X , combined with the high voltage value on the winding L, the insulation resistance R can be accurately calculated without affecting the measured current due to water resistance. X The main parameters related to this are: insulation resistance, absorption ratio and polarization index. The insulation resistance testers for water-cooled generators on the market can generally measure the above parameters.

[0056] However, when measuring some generator sets, sometimes the ground connection on the water collector cannot be disconnected, that is, the water collector is fixedly grounded. At this time, if high voltage is directly applied to the L end of the winding for measurement, the equivalent circuit in the measurement is as follows Figure 2 As shown. W Indicates the resistance of the water branch.

[0057] Figure 3 Flow chart of a method for testing the insulation resistance of a water-cooled generator with a fixedly grounded manifold provided by an embodiment of the present disclosure. Figure 3 , the method comprising:

[0058] Step 101: Adjust cooling water in a water-cooled generator to a first conductivity.

[0059] The conductivity of cooling water is related to the ion content in the cooling water, and the pH can reflect the ion content. Therefore, a relationship model between the conductivity and pH of cooling water can be established in advance. When adjusting the conductivity of cooling water, it can be achieved by adjusting the pH value of cooling water.

[0060] Step 102: When the cooling water has a first conductivity, measuring a first resistance value of an insulation resistance and a water resistance in the water-cooled generator connected in parallel.

[0061] Among them, the insulation resistance is the resistance of the insulation branch, the water resistance is the resistance of the water branch, the water branch is connected in parallel with the insulation branch, and the insulation branch is the branch in which the stator winding in the water-cooled generator is grounded through the base of the water-cooled generator.

[0062] Step 103: Adjust the cooling water in the water-cooled generator to a second conductivity.

[0063] Among them, the second conductivity is not equal to the first conductivity. For example, the first conductivity is a higher conductivity, and the second conductivity is a lower conductivity. The two conductivities are quite different, which can make the resistance values ​​of the water branches corresponding to the two conductivities differ greatly, thereby making the values ​​of the first resistance and the second resistance differ greatly, which is conducive to accurately determining the size of the insulation resistance.

[0064] Step 104: When the cooling water has a second conductivity, measuring a second resistance value of the insulation resistance and the water resistance in the water-cooled generator connected in parallel.

[0065] Step 105: Determine the resistance of the insulation resistor based on the first conductivity, the first resistance, the second conductivity, and the second resistance.

[0066] Since the first resistance is the result of the water branch resistance and the insulation resistance in parallel at the first conductivity, and the second resistance is the result of the water branch resistance and the insulation resistance in parallel at the second conductivity, and since the insulation resistance does not change under the two conductivities, and the conductivity and the water branch resistance are proportional, based on the above relationship, an equation can be established to solve the insulation resistance value.

[0067] In the disclosed embodiment, the resistance of the water branch is changed by changing the conductivity of the cooling water. When the insulation branch resistance remains unchanged, the insulation resistance and the water resistance are measured in parallel under different conductivities. Based on the two conductivities and the corresponding parallel resistance, the insulation resistance value can be determined. This solution can test the insulation resistance of the water-cooled generator without disconnecting the ground connection on the water manifold, ensuring that the insulation resistance value can be measured without disconnecting the ground connection on the water manifold.

[0068] Figure 4 Flow chart of a method for testing the insulation resistance of a water-cooled generator with a fixedly grounded manifold provided by an embodiment of the present disclosure. Figure 4 , the method comprising:

[0069] Step 201: Based on the correspondence between conductivity and pH value, determine the pH value corresponding to the first conductivity.

[0070] The conductivity and pH relationship model of the cooling water is established in advance, and the relationship model is also the corresponding relationship between the conductivity and the pH value. The embodiment of the present disclosure does not limit the method of establishing the conductivity and pH relationship model of the cooling water, as long as the conductivity and pH relationship model of the cooling water can be established.

[0071] Step 202: Control the pH value of the cooling water to be the pH value corresponding to the first conductivity by controlling the flow rate of the desalted water in the cooling water.

[0072] Cooling water can be made by mixing a certain proportion of pure water and desalted water. Usually, the salt in the desalted water is not completely removed and contains trace impurities, so it can be used to adjust the pH value of the cooling water. There is a mature solution for pH adjustment in the relevant technology, and the embodiments of the present disclosure are not limited to this.

[0073] In step 201 and step 202, a target conductivity, namely the first conductivity, is first set, and then the corresponding target pH value is determined through the correspondence between conductivity and pH value, and then the pH value of the cooling water is adjusted to make its conductivity reach the first conductivity.

[0074] In addition to this method, another method is not to set the target conductivity in advance, but to increase or decrease the pH of the cooling water, measure the pH value after the adjustment, and use the conductivity corresponding to the pH value as the first conductivity.

[0075] Alternatively, step 201 and step 202 may also be implemented in the following manner:

[0076] Controlling the pH value of the cooling water by controlling the flow rate of desalted water in the cooling water;

[0077] Based on the correspondence between conductivity and pH value, it is determined that the conductivity corresponding to the pH value of the cooling water is the first conductivity.

[0078] Step 203: When the cooling water has a first conductivity, sampling the output voltage of the high-voltage source and measuring the leakage current of the water-cooled generator, wherein the high-voltage source is used to power the water-cooled generator.

[0079] In the embodiment of the present disclosure, a high voltage sampling unit can be used to sample the output voltage of the high voltage source, and the high voltage sampling unit is connected to the high voltage source; a winding leakage current measurement unit is used to measure the leakage current, and the winding leakage current measurement unit is connected to the water-cooled generator. The signals collected by the high voltage sampling unit and the winding leakage current measurement unit are digitized by the analog-to-digital conversion unit, and then subsequent calculations are performed.

[0080] Step 204: Calculate a first resistance value according to the sampled output voltage and the measured leakage current.

[0081] Here, the first resistance is obtained by dividing the output voltage by the leakage current.

[0082] Step 205: Based on the correspondence between conductivity and pH value, determine the pH value corresponding to the second conductivity.

[0083] Exemplarily, the first conductivity is greater than the second conductivity, and a ratio of a difference between the first conductivity and the second conductivity to the first conductivity is greater than 1 / 2.

[0084] Usually, the conductivity of the water-cooled generator is generally high when it is just shut down. At this time, step 201 and step 202 are executed to control the conductivity of the cooling water between 1.5 and 2.0 μS / cm, and the corresponding water resistance is generally 100 to 300 kΩ. After the water-cooled generator is shut down, steps 205 and 206 are executed to control the conductivity of the cooling water to 0.5 to 0.7 μS / cm, and the corresponding water resistance can be increased to 1 to 5 MΩ. Through the above-mentioned conductivity control, the method provided in the embodiment of the present disclosure can accurately measure the size of the insulation resistance.

[0085] Step 206: Control the pH value of the cooling water to a pH value corresponding to the second conductivity by controlling the flow rate of the desalted water in the cooling water.

[0086] Alternatively, step 205 and step 206 may also be implemented in the following manner:

[0087] Controlling the pH value of the cooling water by controlling the flow rate of desalted water in the cooling water;

[0088] Based on the correspondence between conductivity and pH value, it is determined that the conductivity corresponding to the pH value of the cooling water is the second conductivity.

[0089] The detailed process of steps 205 and 206 can refer to steps 201 and 202, which will not be described in detail here.

[0090] Step 207: When the cooling water has a second conductivity, the output voltage of the high voltage source is sampled, and the leakage current of the water-cooled generator is measured.

[0091] Step 208: Calculate a second resistance value according to the sampled output voltage and the measured leakage current.

[0092] The detailed process of steps 207 and 208 can refer to steps 203 and 204, which will not be described in detail here.

[0093] Step 209: Determine the resistance of the insulation resistor based on the first conductivity, the first resistance, the second conductivity, and the second resistance.

[0094] Optionally, the insulation resistance is calculated according to the following formula:

[0095]

[0096] Among them, R X is the insulation resistance, R M1 is the first resistance value, R M2 is the first resistance value, σ 1 is the first conductivity, σ 2 is the second conductivity.

[0097] Exemplarily, the insulation resistance is generally in the order of hundreds of MΩ.

[0098] The derivation process of formula (1) is explained below:

[0099] Since the water pipe is fixedly grounded, the resistance R of the water branch W And insulation resistance R X In parallel state, the parallel resistance of the two is R M , R M , R X , R W The relationship between can be expressed as formula (2):

[0100]

[0101] R M , R X and R W Taking the reciprocal, we can get their corresponding conductivity value G M , G X and G W The relationship between is shown in formula (3):

[0102]

[0103] After simplifying formula (3), we can get formula (4):

[0104] G M =G W +G X (4)

[0105] In steps 201 to 208, R M Two measurements were conducted, one when the water conductivity was high, and the R M For R M1 , corresponding to the conductivity of cooling water σ 1 , for R M1 Taking the reciprocal gives the corresponding conductivity value G M1 , at this time the resistance of the water branch is R W1 , taking the inverse, we can get the corresponding conductivity value G W1 ; The other time is when the water conductivity is low, and the R M For R M2, corresponding to the water conductivity σ 2 , for R M2 Taking the reciprocal gives the corresponding conductivity value G M2 , at this time the resistance of the water branch is R W2 , taking the inverse, we can get the corresponding conductivity value G W2 .

[0106] In the known R M1 , R M2 , σ 1 , σ 2 Under the condition of X .

[0107] According to formula (4), we can get formula (5):

[0108]

[0109] The resistance R is proportional to the length L of the conductor and inversely proportional to the cross-sectional area S of the conductor, that is, there is formula (6):

[0110]

[0111] Where ρ is the resistivity, then

[0112] Based on formula (6), the relationship between conductance G and resistance R can be obtained, as shown in formula (7):

[0113]

[0114] Here, σ is the electrical conductivity.

[0115] Based on formula (7), we can deduce that G W1 , G W2 With σ 1 , σ 2 The relationship is shown in formula (8):

[0116]

[0117] Transforming formula (8) into formula (9):

[0118]

[0119] make

[0120] From formula (5), formula (9) and (10), we can get:

[0121]

[0122] G Ml -k×G M2=G X -k×G X (12)

[0123]

[0124] Substituting formula (13) and (10) into Then we can get formula (1).

[0125] Figure 5 Schematic diagram of the structure of a water-cooled generator insulation resistance test device with a fixedly grounded water manifold provided by an embodiment of the present disclosure. Figure 5 The device includes: a high voltage source 301, a resistance detection module 302 and a control operation module 303.

[0126] Wherein, the high voltage source 301 is connected to the water-cooled generator and is used to apply voltage to the stator winding of the water-cooled generator;

[0127] The resistance detection module 302 is connected to the water-cooled generator and the high-voltage source 301, respectively, and is used to measure the first resistance value of the insulation resistance and the water resistance in the water-cooled generator in parallel when the cooling water in the water-cooled generator has a first conductivity, the insulation resistance is the resistance of the insulation branch, the water resistance is the resistance of the water branch, the water branch is connected in parallel with the insulation branch, and the insulation branch is a branch for grounding the stator winding in the water-cooled generator through the base of the water-cooled generator; when the cooling water has a second conductivity, measure the second resistance value of the insulation resistance and the water resistance in the water-cooled generator in parallel;

[0128] The control operation module 303 is connected to the resistance detection module 302, and is used to determine the resistance value of the insulation resistance based on the first conductivity, the first resistance value, the second conductivity, and the second resistance value.

[0129] Exemplarily, the resistance detection module 302 includes a high voltage sampling unit 3021 , a winding leakage current measuring unit 3022 and a computing unit 3023 .

[0130] The high voltage sampling unit 3021 is connected to the high voltage source 301 and is used to sample the output voltage of the high voltage source;

[0131] The winding leakage current measuring unit 3022 is connected to the water-cooled generator and is used to measure the leakage current of the water-cooled generator;

[0132] The operation unit 3023 is connected to the high voltage sampling unit 3021 , the winding leakage current measuring unit 3022 and the control operation module 303 respectively, and is used to calculate the first resistance value according to the sampled output voltage and the measured leakage current.

[0133] Optionally, the resistance detection module 302 further includes an analog-to-digital conversion unit for digitizing the analog signals collected by the high voltage sampling unit 3021 and the winding leakage current measurement unit 3022, and then outputting the digitized signals to the operation unit for calculation.

[0134] The operation unit 3023 may be integrated into the control operation module 303 and implemented using the same chip.

[0135] Figure 6 is a circuit diagram of a high voltage sampling unit provided by an embodiment of the present disclosure. Figure 6 , the high voltage sampling unit 3021 includes: a first resistor R31 and a second resistor R32. The first resistor R31 and the second resistor R32 are connected in series between the stator winding and the analog ground AGND, and the connection point of the first resistor R31 and the second resistor R32 is electrically connected to the analog-to-digital conversion unit. The first resistor R31 and the second resistor R32 are voltage divider resistors. Through R31 and R32, the high voltage of 2500 to 10000V is sampled into a voltage sampling signal of 0.5 to 2V, which is sent to the analog-to-digital conversion unit to digitize the high voltage sampling voltage and then output it.

[0136] Figure 7 is a circuit diagram of a winding leakage current measurement unit provided by an embodiment of the present disclosure. Figure 7 The winding leakage current measuring unit 3022 includes: a second operational amplifier U51, a first switch K52, a second switch K53, a fifth resistor R54 and a sixth resistor R55.

[0137] 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.

[0138] One end of the first switch K52 and the second switch K53 are electrically connected and electrically connected to the connection point between 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 between the fifth resistor R54 and the sixth resistor R55 is electrically connected to the output end of the second operational amplifier U51, and the output end of the second operational amplifier U51 is electrically connected to the analog-to-digital conversion unit.

[0139] The closing and opening of the first switch K52 and the second switch K53 are controlled by the control operation module 303. The control operation module 303 is also used to control the first switch K52 to close and the second switch K53 to open, or to control the first switch K52 to open and the second switch K53 to close. The first switch K52 and the second switch K53 are turned on respectively to achieve the leakage current I X The voltage signal V3 is obtained by IV conversion and then sent to the analog-to-digital conversion unit for digitization. X The maximum size is 10 6 The span of a single resistor cannot meet the span, so the embodiment of the present invention sets two resistors with different resistance values ​​for measurement. Specifically, the fifth resistor R54 and the sixth resistor R55 have different values, and the resistance of the fifth resistor R54 is less than the resistance of the sixth resistor R55. The sixth resistor R55 can be used to measure leakage currents below microamperes, and the fifth resistor R54 can be used to measure leakage currents from microamperes to milliamperes. When measuring the leakage current I of the stator winding X During the process, the control operation module 303 first closes the first switch K52 and opens the second switch K53, that is, the fifth resistor R54 (small resistor) is used for measurement. When the voltage signal V3 is greater than the target voltage, the control operation module 303 keeps the first switch K52 closed and the second switch K53 open, and performs subsequent insulation resistance determination; when the voltage signal V3 is less than the target voltage, the control operation module 303 again opens the first switch K52 and closes the second switch K53, that is, the sixth resistor R55 (large resistor) is used for measurement to increase the amplitude of the voltage signal V3.

[0140] Exemplarily, the control operation module 303 is used to calculate the insulation resistance according to the following formula:

[0141]

[0142] Among them, R X is the insulation resistance, R M1 is the first resistance value, R M2 is the first resistance value, σ 1 is the first conductivity, σ 2 is the second conductivity.

[0143] Exemplarily, the first conductivity is greater than the second conductivity, and a ratio of a difference between the first conductivity and the second conductivity to the first conductivity is greater than 1 / 2.

[0144] Exemplarily, the control operation module 303 is connected to the high voltage source 301, and is also used to output control instructions to the high voltage source, wherein the control instructions are used to control the high voltage source to apply voltage to the stator winding of the water-cooled generator.

[0145] It should be noted that: the water-cooled generator insulation resistance test device with a fixedly grounded water manifold provided in the above embodiment only uses the division of the above functional modules as an example when testing the insulation resistance of the water-cooled generator. In actual applications, the above functional distribution can be completed by different functional modules as needed, that is, the internal structure of the device is divided into different functional modules to complete all or part of the functions described above. In addition, the water-cooled generator insulation resistance test device with a fixedly grounded water manifold provided in the above embodiment and the water-cooled generator insulation resistance test method embodiment with a fixedly grounded water manifold belong to the same concept. The specific implementation process is detailed in the method embodiment and will not be repeated here.

[0146] A person skilled in the art will understand that all or part of the steps to implement the above embodiments may be accomplished by hardware or by instructing related hardware through a program, and the program may be stored in a computer-readable storage medium, and the above-mentioned storage medium may be a read-only memory, a disk or an optical disk, etc.

[0147] The above description is only an optional embodiment of the present disclosure and is not intended to limit the present disclosure. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present disclosure shall be included in the protection scope of the present disclosure.

Claims

1. A method for testing the insulation resistance of a water-cooled generator with a fixedly grounded manifold, characterized in that: The method comprises: adjusting cooling water in the water-cooled generator to a first conductivity; When the cooling water has a first conductivity, measuring a first resistance value of an insulation resistance and a water resistance in the water-cooled generator connected in parallel, wherein the insulation resistance is the resistance of an insulation branch, the water resistance is the resistance of a water branch, the water branch is connected in parallel with the insulation branch, and the insulation branch is a branch for grounding a stator winding in the water-cooled generator through a frame of the water-cooled generator; adjusting the cooling water in the water-cooled generator to a second conductivity; When the cooling water has a second conductivity, measuring a second resistance value of an insulation resistance and a water resistance in the water-cooled generator connected in parallel; The resistance value of the insulation resistor is determined based on the first conductivity, the first resistance, the second conductivity, and the second resistance.

2. The method according to claim 1, characterized in that The step of adjusting the cooling water in the water-cooled generator to a first conductivity comprises: Based on the correspondence between conductivity and pH value, determining the pH value corresponding to the first conductivity; By controlling the flow rate of desalted water in the cooling water, the pH value of the cooling water is controlled to be the pH value corresponding to the first conductivity; Alternatively, the step of adjusting the cooling water in the water-cooled generator to a first conductivity includes: Controlling the pH value of the cooling water by controlling the flow rate of desalted water in the cooling water; Based on the correspondence between conductivity and pH value, it is determined that the conductivity corresponding to the pH value of the cooling water is the first conductivity.

3. The method according to claim 1, characterized in that The measuring of a first resistance value of an insulation resistor and a water resistor in the water-cooled generator connected in parallel comprises: Sampling an output voltage of a high voltage source, wherein the high voltage source is used to supply power to the water-cooled generator; Measuring the leakage current of the water-cooled generator; The first resistance value is calculated according to the sampled output voltage and the measured leakage current.

4. The method according to claim 1, characterized in that: The determining the insulation resistance based on the first conductivity, the first resistance, the second conductivity and the second resistance includes: The insulation resistance is calculated according to the following formula: Among them, R X is the insulation resistance, R M1 is the first resistance value, R M2 is the first resistance, σ1 is the first conductivity, and σ2 is the second conductivity.

5. The method according to claim 1, characterized in that The first electrical conductivity is greater than the second electrical conductivity, and a ratio of a difference between the first electrical conductivity and the second electrical conductivity to the first electrical conductivity is greater than 1 / 2.

6. A water-cooled generator insulation resistance test device with a fixed grounded manifold, characterized in that: The device comprises: A high voltage source connected to the water-cooled generator and used to apply voltage to the stator winding of the water-cooled generator; a resistance detection module, connected to the water-cooled generator and the high-voltage source, respectively, and used for measuring a first resistance value of the insulation resistance and the water resistance in the water-cooled generator in parallel when the cooling water in the water-cooled generator has a first conductivity, the insulation resistance being the resistance of the insulation branch, the water resistance being the resistance of the water branch, the water branch being connected in parallel with the insulation branch, the insulation branch being a branch for grounding the stator winding in the water-cooled generator through the base of the water-cooled generator; and measuring a second resistance value of the insulation resistance and the water resistance in the water-cooled generator in parallel when the cooling water has a second conductivity; A control operation module is connected to the resistance detection module, and is used to determine the resistance value of the insulation resistor based on the first conductivity, the first resistance value, the second conductivity and the second resistance value.

7. The device according to claim 6, characterized in that The resistance detection module comprises: A high voltage sampling unit, connected to the high voltage source, and used to sample the output voltage of the high voltage source; A winding leakage current measuring unit, connected to the water-cooled generator, for measuring the leakage current of the water-cooled generator; The operation unit is connected to the high voltage sampling unit, the winding leakage current measuring unit and the control operation module respectively, and is used to calculate the first resistance value according to the sampled output voltage and the measured leakage current.

8. The device according to claim 6, characterized in that The control calculation module is used to calculate the insulation resistance according to the following formula: Among them, R X is the insulation resistance, R M1 is the first resistance value, R M2 is the first resistance, σ1 is the first conductivity, and σ2 is the second conductivity.

9. The device according to claim 6, characterized in that The first electrical conductivity is greater than the second electrical conductivity, and a ratio of a difference between the first electrical conductivity and the second electrical conductivity to the first electrical conductivity is greater than 1 / 2.

10. The device according to claim 6, characterized in that The control operation module is connected to the high voltage source and is also used to output control instructions to the high voltage source, wherein the control instructions are used to control the high voltage source to apply voltage to the stator winding of the water-cooled generator.

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