CN115825731A - Synchronous generator insulation fault detection device and method thereof - Google Patents

Abstract

The invention discloses a synchronous generator insulation fault detection device and a method thereof, wherein the synchronous generator comprises a winding, and the winding is a stator winding or a rotor winding; the insulation fault detection device includes: one or more of a direct current voltage drop detection unit, a voltage impact detection unit or an open-end transformer detection unit; therefore, when the synchronous generator breaks down, the fault position can be quickly positioned by the detection device and the detection method, so that workers can be helped to overhaul in time, the power failure time is shortened, and the loss is reduced.

Description

Synchronous generator insulation fault detection device and method thereof

Technical Field

The invention relates to the technical field of power equipment detection, in particular to a synchronous generator insulation fault detection device and a method thereof.

Background

The large synchronous generator is an important component in a power system, and the insulation performance of a stator and a rotor of the large synchronous generator can be gradually degraded and even broken down when being seriously influenced by factors such as high voltage, large current, high temperature, vibration and the like for a long time in operation. When the insulation of the stator or the rotor of the generator breaks down, the stator bar or the rotor winding is shorted to the ground, so that the equipment is not shut down unexpectedly, and the normal power supply of a user is influenced.

However, the problem with this method is that the current fault detection method can only detect which branch has a fault, but cannot accurately locate which bar on the branch has a fault. Like this, when large-scale synchronous generator takes place the insulation breakdown trouble, unable quick, accurate, convenient synchronous generator insulation fault positioner will help the maintainer to find the insulation fault point fast, judge insulating situation, lead to unable for planning the maintenance period, formulate maintenance scheme and work such as spare parts calculation provide the support, can not help fortune dimension unit resume equipment operation as early as possible, increased the power off time, cause very big loss.

Disclosure of Invention

The invention provides a synchronous generator insulation fault detection device and method, which are used for rapidly, accurately and conveniently positioning the insulation fault of a synchronous generator, reducing the power failure time and reducing the loss.

In order to achieve the above object, an embodiment of an aspect of the present invention provides an insulation fault detection apparatus for a synchronous generator, where the synchronous generator includes a winding, and the winding is a stator winding or a rotor winding; the insulation fault detection device includes:

one or more of a direct current voltage drop detection unit, a voltage impact detection unit or an open-end transformer detection unit;

the direct current voltage drop detection unit is used for providing a constant direct current to two ends of an outlet side and a neutral point side of any branch of any phase in the winding, generating a third voltage at two ends when the constant direct current flows through the branch, and detecting the winding insulation fault according to a first voltage between the outlet side and a ground side of the branch, a second voltage between the neutral point side and the ground side of the branch and the third voltage;

the voltage impact detection unit is used for providing a third direct current to an outlet side of any branch of any phase in the winding, and detecting the winding insulation fault according to a first current peak value of the outlet side of the branch, a second current peak value of the neutral point side and/or a discharge phenomenon appearing in the branch;

the open-end transformer detection unit is used for providing a third alternating current to the outlet side of any branch of any phase in the stator winding and detecting the insulation fault of the stator winding according to the induced current of the secondary winding of the open-end transformer in the open-end transformer detection unit; the iron core of the open-end transformer is positioned in the stator iron core slot part and is coupled with the stator iron core to form the current transformer.

Optionally, the dc drop detection unit includes:

the first voltage collector is positioned between the outlet side and the grounding side of any branch of any phase in the winding and is used for collecting first voltage;

the second voltage collector is positioned between the neutral point side and the grounding side of any branch of any phase in the winding and used for collecting second voltage;

the third voltage collector is positioned at the outlet side of any branch of any phase in the winding and two ends of the neutral point side and is used for collecting third voltage;

a direct current source electrically connected to both ends of the outlet side and the neutral point side of any branch of any phase in the winding;

and the first controller is respectively connected with the first voltage collector, the second voltage collector, the third voltage collector and the direct current source and is used for judging the insulation fault of the winding when the sum of the first voltage and the second voltage is the third voltage and the absolute value of the first voltage and the absolute value of the second voltage are both greater than 0.

Optionally, the first controller is further configured to calculate a ratio between an absolute value of the first voltage and a sum of the absolute value of the first voltage and the absolute value of the second voltage, and to obtain a location of a faulty bar in relation to a total number of bars of the branch.

Optionally, the dc drop detection unit further includes: the input end of the module converter is respectively connected with the output end of the first voltage collector, the output end of the second voltage collector and the output end of the third voltage collector, the output end of the module converter is connected with the first controller, and the display is connected with the first controller.

Optionally, the voltage surge detection unit includes:

the device comprises a direct current voltage generator, a charging capacitor, an electric control switch, a first impact current peak value collector, a second impact current peak value collector and a second controller;

the output end of the direct current voltage generator is respectively connected with one end of the charging capacitor and the first end of the electric control switch, the other end of the charging capacitor is grounded, the other end of the electric control switch is connected with the opening side of the branch, the first impact current peak value collector is positioned at the opening side and used for collecting a first current peak value, and the second impact current peak value collector is positioned at the neutral point side and used for collecting a second current peak value;

the second controller is respectively connected with the control end of the electric control switch, the first impact current peak value collector and the second impact current peak value collector and is used for acquiring the first current peak value and the second current peak value to detect the winding insulation fault when the electric control switch is switched on.

Optionally, the electrically controlled switch is a controllable ball gap.

Optionally, the open transformer detection unit further includes:

the output edge of the isolation transformer is coupled with the primary edge of the voltage regulator, and the secondary edge of the voltage regulator is connected with one end of any branch of any phase of a stator winding of the synchronous generator and used for providing a third alternating current for the branch;

the alternating current collector is positioned on the secondary winding of the open-end transformer and used for collecting the alternating current of the secondary winding of the open-end transformer; the two ends of the open-end transformer can be attached to the surface of the slot part of the stator core to move;

and the third controller is connected with the alternating current collector and used for detecting the winding insulation fault according to the alternating current collected by the alternating current collector.

Optionally, the secondary side of the voltage regulator is connected to two ends of any branch of any phase of the stator winding of the synchronous generator, and is used for providing a third alternating current with variable amplitude to the branch.

In order to achieve the above object, a method for detecting an insulation fault of a synchronous generator is provided in a second aspect of the present invention, which is implemented based on the apparatus for detecting an insulation fault of a synchronous generator according to any embodiment of the present invention, and includes the following steps:

acquiring the insulation resistance of any branch of any phase in the synchronous generator to the ground;

and determining a branch with a fault according to the size of the insulation resistance, and positioning a bar with the fault in the branch.

Optionally, the determining a branch with a fault according to the size of the insulation resistance and locating a bar with a fault in the branch comprises:

if the insulation resistance is smaller than or equal to a preset value, controlling any one detection unit of the direct current voltage drop detection unit, the voltage impact detection unit or the open-ended transformer detection unit to start to perform fault location detection;

and if the insulation resistance is larger than the preset value, controlling the voltage impact detection unit to start, and after a discharge phenomenon occurs, controlling the open-end transformer detection unit or the direct current voltage drop detection unit to start to perform fault location detection.

According to the device and the method for detecting the insulation fault of the synchronous generator, provided by the embodiment of the invention, the synchronous generator comprises a winding, wherein the winding is a stator winding or a rotor winding; the insulation fault detection device includes: one or more of a direct current voltage drop detection unit, a voltage impact detection unit or an open-end transformer detection unit; the direct current voltage drop detection unit is used for providing a constant direct current to two ends of an outlet side and a neutral point side of any branch of any phase in the winding, generating a third voltage at two ends when the constant direct current flows through the branch, and detecting the insulation fault of the winding according to the first voltage between the outlet side and the grounding side of the branch, the second voltage between the neutral point side and the grounding side of the branch and the third voltage; the voltage impact detection unit is used for providing a third direct current to the outlet side of any branch of any phase in the winding, and detecting the insulation fault of the winding according to a first current peak value on the outlet side of the branch, a second current peak value on the neutral point side or a discharge phenomenon in the branch; the open transformer detection unit is used for providing a third alternating current to the outlet side of any branch of any phase in the stator winding and detecting the insulation fault of the stator winding according to the induced current of the secondary winding of the open transformer in the open transformer detection unit; the iron core of the open-end transformer is positioned in the stator iron core slot part and is coupled with the stator iron core to form the current transformer. Therefore, when the synchronous generator breaks down, the fault position can be quickly positioned by the detection device and the detection method, so that workers can be helped to overhaul in time, the power failure time is shortened, and the loss is reduced.

It should be understood that the statements in this section are not intended to identify key or critical features of the embodiments of the present invention, nor are they intended to limit the scope of the invention. Other features of the present invention will become apparent from the following description.

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 introduced 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 based on these drawings without creative efforts.

Fig. 1 is a block diagram of a synchronous generator insulation fault detection apparatus according to an embodiment of the present invention;

fig. 2 is a schematic structural diagram of a dc voltage drop detection unit in the synchronous generator insulation fault detection apparatus according to the embodiment of the present invention;

fig. 3 is a schematic structural diagram of a voltage surge detection unit in the insulation fault detection apparatus for a synchronous generator according to the embodiment of the present invention;

fig. 4 is a schematic structural diagram of a detection unit of an open-end transformer in the insulation fault detection device of the synchronous generator according to the embodiment of the present invention;

fig. 5 is a block diagram of a dc voltage drop detection unit in the insulation fault detection apparatus for a synchronous generator according to the embodiment of the present invention;

fig. 6 is a block diagram of a dc drop detection unit in the insulation fault detection apparatus of the synchronous generator according to an embodiment of the present invention;

fig. 7 is a topology diagram of a dc drop detection unit in the insulation fault detection apparatus of the synchronous generator according to an embodiment of the present invention;

fig. 8 is a developed view of a stator winding branch of a generator in the insulation fault detection apparatus for a synchronous generator according to the embodiment of the present invention;

fig. 9 is a diagram showing a detection result of the dc voltage drop detection unit of the generator in the synchronous generator insulation fault detection apparatus according to the embodiment of the present invention;

fig. 10 is a schematic structural diagram of a voltage surge detection unit in the insulation fault detection apparatus of the synchronous generator according to an embodiment of the present invention;

fig. 11 is a topology diagram of a voltage surge detection unit in the insulation fault detection apparatus of the synchronous generator according to an embodiment of the present invention;

fig. 12 is a schematic structural diagram of an open-end transformer detection unit in the insulation fault detection apparatus for a synchronous generator according to an embodiment of the present invention;

fig. 13 is a topology diagram of the open-ended transformer detection unit in the synchronous generator insulation fault detection apparatus according to an embodiment of the present invention.

Detailed Description

In order to make the technical solutions of the present invention better understood, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be obtained by a person skilled in the art without making any creative effort based on the embodiments in the present invention, shall fall within the protection scope of the present invention.

It should be noted that the terms "first," "second," and the like in the description and claims of the present invention and in the drawings described above are used for distinguishing between similar elements and not necessarily for describing a particular sequential or chronological order. It is to be understood that the data so used is interchangeable under appropriate circumstances such that the embodiments of the invention described herein are capable of operation in sequences other than those illustrated or described herein. Furthermore, the terms "comprises," "comprising," and "having," and any variations thereof, are intended to cover a non-exclusive inclusion, such that a process, method, system, article, or apparatus that comprises a list of steps or elements is not necessarily limited to those steps or elements expressly listed, but may include other steps or elements not expressly listed or inherent to such process, method, article, or apparatus.

Fig. 1 is a block diagram of a synchronous generator insulation fault detection apparatus according to an embodiment of the present invention.

The synchronous generator comprises a winding, wherein the winding is a stator winding or a rotor winding; as shown in fig. 1, the insulation fault detection apparatus includes:

one or more of a direct current voltage drop detection unit 101, a voltage impact detection unit 102 or an open-end transformer detection unit 103;

the direct current drop detection unit 101 is configured to provide a constant direct current to both ends of an outlet side 201 and a neutral point side 202 of any branch 300 of any phase in the winding, generate a third voltage at both ends when the constant direct current flows through the branch, and detect a winding insulation fault according to a first voltage between the outlet side 201 and a ground side 203 of the branch 300, a second voltage between the neutral point side 202 and the ground side 203 of the branch 300, and the third voltage;

the voltage surge detection unit 102 is used for supplying a third direct current to the outlet side 201 of any branch 300 of any phase in the winding, and detecting the insulation fault of the winding according to a first current peak value of the outlet side 201 of the branch 300 and a second current peak value of the neutral point side 202, and/or a discharge phenomenon occurring in the branch 300;

the open transformer detection unit 103 is configured to supply a third alternating current to the outlet side 201 of any branch 300 of any phase in the stator winding, and detect a stator winding insulation fault according to an induced current of the secondary winding of the open transformer 104 in the open transformer detection unit 103; the iron core of the open-end transformer 104 is located in the slot of the stator core, and is coupled with the stator core to form a current transformer.

It is understood that the insulation fault detection apparatus may detect a fault of the synchronous generator by one or several of the three fault detection units.

If the dc drop detection unit 101 is used for detection, the principle is as follows: as shown in fig. 2, the voltage can be provided to the exit side 201 and the neutral side 202 of any branch 300 in the winding, i.e. a direct current can be provided to the branch 300, and then the voltage to ground of the exit side 201 and the voltage to ground of the neutral side 202, and the voltage between the exit side 201 and the neutral side 202 can be measured; if the branch 300 does not fail and the voltage between the exit side 201 and the neutral side 202 is U3, the voltage U1 to the ground on the exit side 201 is 0V and the voltage U2 to the neutral side 202 is U3, or the voltage U2 to the ground on the neutral side 202 is 0V and the voltage U1 to the ground on the exit side 201 is U3. If the branch 300 fails, a ground resistance exists between the failed part of the branch 300 and the ground, and the voltage U1 to the ground on the outlet side 201 and the voltage U2 to the ground on the neutral side 202 are not 0V. Therefore, when the voltage to ground of the outlet side 201U 1 and the voltage to ground of the neutral point side 202U 2 are not both 0V, the fault of the synchronous generator can be judged, and further, whether the branch has the fault or not can be judged according to the obtained voltage to ground of the outlet side 201U 1 and the voltage to ground of the neutral point side 202U 2. And also locates the bar location of the faulty branch based on the outlet side 201 voltage to ground U1, the neutral side 202 voltage to ground U2 being a proportion of the voltage U3 between the outlet side 201 and the neutral side 202.

When the voltage surge detection unit 102 is used for detection, the principle is as follows: as shown in fig. 3, a third direct current is supplied to the outlet side 201 of any branch 300 of any phase in the winding, and if the branch 300 is not failed, the current supplied to the outlet side 201 is I3, the detected current I1 of the outlet side 201 is I3, and the current I2 of the neutral point side 202 is not 0; if the branch 300 fails, the detected current I1 on the outlet side 201 is I3, and the current I2 on the neutral point side 202 is 0, i.e. some part of the middle of the branch 300 is grounded, so that the current flows from the middle of the branch 300 to the ground, resulting in I2 being 0. Thus, it can be determined whether the branch 300 is faulty or not, depending on whether the current I2 at the neutral point side 202 is 0 or not. In addition, when the third dc current is applied to the branch 300, if the branch 300 does not fail, the branch 300 does not discharge, and if the branch 300 fails, the branch 300 may generate a discharge sound or a discharge spark to locate the failure position. In one embodiment, the branch 300 fault can be determined by whether the current I2 on the neutral side 202 is 0, and the fault location can be located by a discharge phenomenon or by sound.

When the open-end transformer detection unit 103 is used for detection, the principle is as follows: as shown in fig. 4, a third ac current is supplied to the outlet side 201 of any branch 300 of any phase in the winding, and the opening of the open-type transformer 104 is coupled with the slot portion of the stator core to form a current transformer, and further, the stator core and the branch winding on the core are the primary winding of the current transformer, and the winding on the open-type transformer 104 is the secondary winding. When the branch 300 is not in fault, no induced current is induced in the secondary winding of the open-end transformer 104, when the branch 300 is in fault, the branch 300 is connected to the earth grid, the current flows into the earth grid through the stator core through the fault point, and the induced current can be induced in the secondary winding of the open-end transformer 104, so that whether the branch is in fault or not can be judged by judging whether the secondary winding of the open-end transformer 104 has the induced current or not, and the fault position of the branch can be positioned.

It should be noted that the dc drop detection unit 101 can mainly detect and locate a fault with a small ground fault resistance, and when the ground fault resistance is large, a bar with a fault cannot be located with a simple voltage ratio. Therefore, the voltage impact detection unit 102 can be used to discharge the branch fault position to reduce the ground fault resistance, and then the direct current voltage drop detection unit 101 can be used to locate the fault. That is, the respective detection units complement each other and can also be used as a way of mutual authentication.

The composition of each detection unit is described below.

Alternatively, as shown in fig. 2, 5, 6, and 7, the dc drop detection unit 101 includes:

a first voltage collector 401, located between the outlet side 201 and the grounding side 203 of any branch 300 of any phase in the winding, for collecting a first voltage U1;

a second voltage collector 402, located between the neutral point side 202 and the ground side 203 of any branch 300 of any phase in the winding, for collecting a second voltage U2;

a third voltage collector 403, located at two ends of the outlet side 201 and the neutral point side 202 of any branch 300 of any phase in the winding, for collecting a third voltage U3;

a dc current source 404 electrically connected to both ends of the outlet side 201 and the neutral point side 202 of any of the branches 300 of any of the phases in the winding;

the first controller 405 is connected to the first voltage collector 401, the second voltage collector 402, the third voltage collector 403, and the dc current source 404, and is configured to determine that the winding insulation fault occurs when the sum of the first voltage U1 and the second voltage U2 is the third voltage U3, and the absolute value of the first voltage U1 and the absolute value of the second voltage U2 are both greater than 0.

The first controller 405 is also arranged to calculate the ratio between the absolute value of the first voltage U1 and the sum of the absolute value of the first voltage U1 and the absolute value of the second voltage U2 and to obtain the location of the faulty bar in relation to the total number X of bars of the branch.

The main function of the dc current source 404 is to provide a dc output current to the branch of the generator stator winding to be tested. And the current (10A, 20A, 50A, 100A adjustable step) from the dc current source 404 is directed to one of the branches of one of the phases of the generator stator winding.

That is, when it is detected that the first voltage U1 is not 0 and the second voltage U2 is not U3, when it is detected that the second voltage U2 is not 0 and the first voltage U1 is not U3, that is, when the first voltage U1 and the second voltage U2 are not 0, the branch fault is determined, and ohm's law can be passed

To locate the fault location. Where X1 denotes a direct current resistance of the fault point from the outlet of the generator, X2 denotes a direct current resistance of the fault point from the neutral point side of the generator, X denotes a direct current resistance of the outlet side to the neutral point side, and R denotes a ground resistance.

When the grounding resistance R is small and the internal resistance of the voltmeter is large enough, U1+ U2 ≈ U3 should be provided.

Therefore, when | U1| + | U2| ≈ U3|, U1 ≠ 0, and U2 ≠ 0, it can be determined that there is a metallic ground fault on the branch; when U1 ≠ 0= U3, U2=0 or U2 ≠ 0= U3, U1=0, then the fault of this branch can be excluded. When positioning is carried out after a fault, calculation can be carried out through software which is designed in advance and embedded into the device unit, and a fault diagnosis result is directly obtained through testing and software operation.

As shown in fig. 6 and 7, the dc drop detection unit 101 further includes: an analog-to-digital converter 406 and a display 407, wherein an input end of the module converter 406 is connected to an output end of the first voltage collector 401, an output end of the second voltage collector 402, and an output end of the third voltage collector 403, an output end of the module converter 406 is connected to the first controller 405, and the display 407 is connected to the first controller 405.

The analog-to-digital converter 406 may convert the analog voltage collected by each voltage collector into a digital voltage for the first controller 405 to calculate. After the first controller 405 calculates the failure result, the failure result may be displayed on the display screen 407. That is, the first controller 405 may be shown outputting a winding bar number fraction for a ground fault, a fault location bar number, a bar number for which troubleshooting is recommended. It will be appreciated that the first controller 405 has a corresponding acquisition processing unit therein.

The practical use of this method is demonstrated by an example below.

E1 The terms (E11, E12, E13) refer to the outlet-side connection point of one branch of a certain phase (sharing ABC three phases) of the generator of a certain power plant, and the terms S11, S12, S13 refer to the neutral-side connection point of one branch of a certain phase (sharing ABC three phases) of the generator. In the stator winding of the generator, a plurality of branches are connected in parallel.

As shown in fig. 8, which is a diagram of the B-phase winding of the generator of the plant, E21, E22, E23 are the generator outlet side E2 ends, three of them are welded together by copper bars in the actual connection, and S21, S22, S23 are the generator neutral point side S2 ends, and they are connected together by screws and copper bars in the actual connection and can be disassembled (in some generator branches, they cannot be disassembled).

When E2 (E21, E22, E23) and S21 are selected after the phase B of the plant fails, the uppermost branch is taken by a current loop of a direct current resistance test, when the direct current voltage U1 of the E2 (E21, E22, E23) to the ground, the direct current voltage U2 of the S21 to the ground and the voltage U3 between the E2 (E21, E22, E23) and the S21 are passed through, the percentage U1/(U1 + U2) of the position of the grounding point in the whole winding length can be calculated through a formula, the total number X of bars of the branch is multiplied by the percentage, the number X1 of bars of the fault position away from an outlet or the number X2 of bars away from a neutral point can be obtained, and the number of the fault can be determined by combining a stator winding expansion diagram.

Since there is also a certain deviation in this calculated value due to the crossed copper bars between the bars of the actual generator, the proposed troubleshooting positions given by the software also include the last number and the next number of the faulty bar number that we determined, and the display screen 407 displays the contents as shown in fig. 9.

Alternatively, as shown in fig. 10 and 11, the voltage surge detection unit 102 includes:

a direct current voltage generator 501, a charging capacitor 502, an electric control switch 503, a first impact current peak value collector 504, a second impact current peak value collector 505 and a second controller 506;

the output end of the dc voltage generator 501 is connected to one end of the charging capacitor 502 and the first end of the electronic control switch 503, the other end of the charging capacitor 502 is grounded, the other end of the electronic control switch 503 is connected to the opening side 201 of the branch 300, the first inrush current peak collector 504 is located on the opening side 202 of the branch 300 and is used for collecting a first current peak I1, and the second inrush current peak collector 505 is located on the neutral point side 202 of the branch 300 and is used for collecting a second current peak I2;

the second controller 506 is connected to the control terminal of the electronic control switch 503, the first inrush current peak collector 504, and the second inrush current peak collector 505, respectively, and is configured to obtain the first current peak and the second current peak to detect a winding insulation fault when the electronic control switch 503 is turned on.

Optionally, the electronically controlled switch 503 is a controllable ball gap.

The unit 102 is mainly applied to non-metallic ground fault finding or accurate physical position positioning after the direct current drop detection unit 101 is positioned. Namely, when the generator has a high-resistance ground fault, the direct current drop detection unit 101 cannot perform test positioning, or when an accurate fault position needs to be determined after the direct current drop detection unit 101 performs a test, high voltage is adopted to impact a fault branch winding, so that the phenomena of discharge sound, discharge sparks, pulse current of the winding and the like are generated at the ground fault, and operation and maintenance personnel are helped to quickly find the ground fault position. The unit 102 further comprises: the instrument panel, the case and the like are auxiliary components of the equipment, so that the equipment is convenient to operate and safe to transport.

The dc voltage generator 501 mainly generates a dc high voltage with adjustable voltage, and outputs the dc high voltage to the charging capacitor 502 to charge the dc high voltage, so as to provide energy for high voltage impact. The charging capacitor 502 receives energy from the dc high voltage generator and stores it for discharging under the control of the controllable spherical gap. The controllable ball gap is a switch capable of adjusting the discharge voltage, and the discharge of the high voltage is performed under the control of the second controller 506. The high-voltage cable provides an electric path for discharging direct-current high voltage in the capacitor to the high resistance of the generator and ensures the insulation between the high voltage and the ground and other equipment. And the impact current peak value collector 504/505 is used for collecting the peak discharge current flowing through the stator winding of the generator when the charging capacitor discharges, and the current is discharged from the high-voltage capacitor, passes through the high-voltage cable and the generator winding and flows to the grounding grid through the stator core at a fault point. When the peak current is collected, the method is realized by a flexible coil clamp type current meter, the highest peak current value is obtained by a 'hold' function, the upper end and the lower end of a certain stator bar are respectively provided with a peak current collecting discharge current, and whether a fault exists in the middle of the winding can be qualitatively judged. The first current peak collector 504 can feed back to the second controller 506 to adjust the size of the controllable ball gap, and the second current peak collector 505 can feed back to the second controller 506 to determine whether the branch has a fault.

When a ground fault occurs in a stator winding or a rotor winding of a generator, a conductor portion of the generator is generally not directly electrically connected to the ground, and a small gap exists between a conductor of the fault point and a grounding body. When the energy stored in the capacitor is released through the controllable ball gap, gap discharge can occur at the gap of a fault point, discharge sound and discharge sparks are generated, operation and maintenance personnel can be helped to find out the fault position quickly, maintenance strategies can be formulated, and the power failure time of equipment can be reduced. Meanwhile, in the energy release process, impact current can be generated in the winding, the peak current of the upper end part and the lower end part of a certain stator bar is tested through a flexible clamp-on ammeter, and operation and maintenance personnel can be helped to qualitatively judge whether the bar is a fault bar or not. The method has a good effect on the failure that the discharge spark cannot be directly seen.

In order to prevent the damage of the stator iron core of the generator caused by high voltage impact, the device is used for fault location, namely the voltage is preferably low firstly and then high, and the voltage is not required to be promoted after the obvious discharge phenomenon occurs.

Optionally, as shown in fig. 10, the open transformer detection unit 103 further includes:

the system comprises an isolation transformer 601 and a voltage regulator 602, wherein the output side of the isolation transformer 601 is coupled with the primary side of the voltage regulator 602, and the secondary side of the voltage regulator 602 is connected with one end of any branch of any phase of a stator winding of the synchronous generator and used for providing a third alternating current for the branch 300;

an ac current collector 603, located on the secondary winding of the open-end transformer 104, for collecting ac current of the secondary winding of the open-end transformer 104; wherein, two ends of the open-end transformer 104 can move by being attached to the surface of the slot part of the stator core;

and a third controller 604 connected to the ac current collector 603, for detecting a winding insulation fault according to the ac current collected by the ac current collector 603.

Optionally, the secondary side of the voltage regulator 602 is connected across any branch of any phase of the stator winding of the synchronous generator for providing a third alternating current of varying amplitude to the branch 300.

The isolation transformer 601 mainly serves to isolate the device from the power supply and prevent the power supply side from tripping when the current is directly output to the ground fault. The voltage regulator 602 is used for regulating the output voltage of the device so as to control the output current and prevent the stator core of the generator from being damaged during the test. The current collector on the voltage regulator 602 is used for detecting the voltage and current parameters output to the generator winding, so that operation and maintenance personnel can regulate the output voltage and current according to requirements. At the same time, the current value detected from the secondary winding of the opening transformer 104, thereby confirming the fault location.

The open transformer 104 is used for coupling in the slot of the generator stator core, and forms a current transformer together with the iron core and the in-slot line bar, and outputs the detected current flowing in the line bar to the ac current collector 603 of the open transformer 104.

The device can also comprise an insulating rod for fixing the open-ended transformer, so that operation and maintenance personnel can safely operate the open-ended transformer to move and detect. And the test cable, the instrument panel, the case and the like are auxiliary components of the equipment, so that the equipment is convenient to operate, and the man-machine interaction and the transportation safety are realized.

The open transformer detection unit 103 has wider adaptability to different stator ground faults, and the main principle is that an open transformer 104 is coupled with a generator stator core to form a current transformer. The open core of the open transformer 104 and the stator core of the generator form a magnetic loop, the bar in the coupled stator core slot is used as the primary coil of the current transformer, and the coil arranged on the open transformer 104 is used as the secondary coil. When detecting that an ac source in the detection unit is applied to the generator ground fault branch, the current will flow through the core to the ground grid through the fault point, and the current will be detected at the secondary coil of the open-ended transformer coupled to the core. When the open-end transformer moves up and down in the stator core slot part, the point from the existence to the nonexistence of the detected current is the fault point, and the ground fault position of the generator can be quickly found in the past.

The current collector in the above embodiment is an ammeter, and the voltage collector is a voltmeter. Therefore, the direct current voltage drop detection unit 101, the voltage impact detection unit 102 and the open-end transformer detection unit 103 are used jointly, and the breakdown fault of the insulator of the large synchronous generator can be quickly searched and confirmed.

The embodiment of the invention also provides a synchronous generator insulation fault detection method, which is realized based on the synchronous generator insulation fault detection device of any embodiment of the invention and comprises the following steps:

acquiring the insulation resistance of any branch of any phase in the synchronous generator to the ground; where this can be detected by a rocking table, it is estimated that the branch may be faulty when the insulation resistance is detected to be not meeting the criterion for the resistance of the branch.

The branch with the fault is determined according to the size of the insulation resistance, and a bar with the fault in the branch is positioned.

Optionally, determining the branch having the fault according to the size of the insulation resistance, and positioning the bar having the fault in the branch comprises:

if the insulation resistance is smaller than or equal to a preset value, controlling any one detection unit of a direct current voltage drop detection unit, a voltage impact detection unit or an open-end transformer detection unit to start to carry out fault location detection;

and if the insulation resistance is larger than the preset value, controlling the voltage impact detection unit to start, and after the discharge phenomenon occurs, controlling the open-end transformer detection unit or the direct current voltage drop detection unit to start to perform fault location detection.

It can be understood that the preset value can be in kilohm level, and when the preset value is larger than the kilohm level, the voltage impact detection unit can be started to reduce the fault resistance value, and then the direct current voltage drop detection unit is started to perform fault detection; the detection unit less than or equal to the kilohm level can be directly selected from any one of a direct current voltage drop detection unit, a voltage impact detection unit or an open-ended transformer detection unit to detect and position. Wherein, stator winding faults can be detected by the method. If the rotor winding is detected to be in fault, the voltage impact detection unit can be started to reduce the fault resistance value firstly when the level is higher than the kilohm level, and then the direct current voltage drop detection unit is started to carry out fault detection; the kilohm level or less can be detected by adopting one of a direct current voltage drop detection unit and a voltage impact detection unit.

In other embodiments, the voltage surge detection unit may also be activated after the dc drop detection unit for further positioning. The three detection units can be mutually authenticated and a standby unit. The detection principle of the three detection units has been described in detail in the apparatus section, and is not described in detail here.

In summary, according to the apparatus and method for detecting an insulation fault of a synchronous generator provided by the embodiments of the present invention, the synchronous generator includes a winding, and the winding is a stator winding or a rotor winding; the insulation fault detection device includes: one or more of a direct current voltage drop detection unit, a voltage impact detection unit or an open-end transformer detection unit; the direct current voltage drop detection unit is used for providing a constant direct current to two ends of an outlet side and a neutral point side of any branch of any phase in the winding, generating a third voltage at two ends when the constant direct current flows through the branch, and detecting the insulation fault of the winding according to the first voltage between the outlet side and the grounding side of the branch, the second voltage between the neutral point side and the grounding side of the branch and the third voltage; the voltage impact detection unit is used for providing a third direct current to the outlet side of any branch of any phase in the winding, and detecting the insulation fault of the winding according to a first current peak value on the outlet side of the branch, a second current peak value on the neutral point side or a discharge phenomenon in the branch; the open transformer detection unit is used for providing a third alternating current to the outlet side of any branch of any phase in the stator winding and detecting the insulation fault of the stator winding according to the induced current of the secondary winding of the open transformer in the open transformer detection unit; the iron core of the open-end transformer is positioned in the stator iron core slot part and is coupled with the stator iron core to form the current transformer. Therefore, when the synchronous generator breaks down, the fault position can be quickly positioned by the detection device and the detection method, so that workers can be helped to overhaul in time, the power failure time is shortened, and the loss is reduced.

It should be understood that various forms of the flows shown above may be used, with steps reordered, added, or deleted. For example, the steps described in the present invention may be executed in parallel, sequentially, or in different orders, and are not limited herein as long as the desired results of the technical solution of the present invention can be achieved.

The above-described embodiments should not be construed as limiting the scope of the invention. It should be understood by those skilled in the art that various modifications, combinations, sub-combinations and substitutions may be made in accordance with design requirements and other factors. Any modification, equivalent replacement, and improvement made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims (10)

1. The device for detecting the insulation fault of the synchronous generator is characterized in that the synchronous generator comprises a winding, wherein the winding is a stator winding or a rotor winding; the insulation fault detection device includes:

one or more of a direct current voltage drop detection unit, a voltage impact detection unit or an open-end transformer detection unit;

the direct current voltage drop detection unit is used for providing a constant direct current to two ends of an outlet side and a neutral point side of any branch of any phase in the winding, generating a third voltage at two ends when the constant direct current flows through the branch, and detecting the winding insulation fault according to a first voltage between the outlet side and a ground side of the branch, a second voltage between the neutral point side and the ground side of the branch and the third voltage;

the voltage impact detection unit is used for providing a third direct current to an outlet side of any branch of any phase in the winding, and detecting the winding insulation fault according to a first current peak value of the outlet side of the branch, a second current peak value of the neutral point side and/or a discharge phenomenon appearing in the branch;

the open-end transformer detection unit is used for providing a third alternating current to the outlet side of any branch of any phase in the stator winding and detecting the insulation fault of the stator winding according to the induced current of the secondary winding of the open-end transformer in the open-end transformer detection unit; the iron core of the open-end transformer is positioned in the stator iron core slot part and is coupled with the stator iron core to form the current transformer.

2. The synchronous generator insulation fault detection device of claim 1, wherein the dc drop detection unit comprises:

the first voltage collector is positioned between the outlet side and the grounding side of any branch of any phase in the winding and is used for collecting first voltage;

the second voltage collector is positioned between the neutral point side and the grounding side of any branch of any phase in the winding and used for collecting second voltage;

the third voltage collector is positioned at the outlet side of any branch of any phase in the winding and two ends of the neutral point side and is used for collecting third voltage;

a direct current source electrically connected to both ends of the outlet side and the neutral point side of any branch of any phase in the winding;

and the first controller is respectively connected with the first voltage collector, the second voltage collector, the third voltage collector and the direct current source and is used for judging the insulation fault of the winding when the sum of the first voltage and the second voltage is the third voltage and the absolute value of the first voltage and the absolute value of the second voltage are both greater than 0.

3. The synchronous generator insulation fault detection device of claim 2, wherein the first controller is further configured to calculate a ratio between an absolute value of the first voltage and a sum of the absolute value of the first voltage and the absolute value of the second voltage, and obtain a location of a faulty bar in conjunction with a total number of bars of the branch.

4. The synchronous generator insulation fault detection device according to claim 2 or 3, further comprising: the input end of the module converter is respectively connected with the output end of the first voltage collector, the output end of the second voltage collector and the output end of the third voltage collector, the output end of the module converter is connected with the first controller, and the display is connected with the first controller.

5. The synchronous generator insulation fault detection device according to claim 1, wherein the voltage surge detection unit includes:

the device comprises a direct current voltage generator, a charging capacitor, an electric control switch, a first impact current peak value collector, a second impact current peak value collector and a second controller;

the output end of the direct current voltage generator is respectively connected with one end of the charging capacitor and the first end of the electric control switch, the other end of the charging capacitor is grounded, the other end of the electric control switch is connected with the opening side of the branch, the first impact current peak value collector is positioned on the outlet side and used for collecting a first current peak value, and the second impact current peak value collector is positioned on the neutral point side and used for collecting a second current peak value;

the second controller is respectively connected with the control end of the electric control switch, the first impact current peak value collector and the second impact current peak value collector and is used for acquiring the first current peak value and the second current peak value to detect the winding insulation fault when the electric control switch is switched on.

6. The synchronous generator insulation fault detection device of claim 5, wherein the electrically controlled switch is a controllable ball gap.

7. The synchronous generator insulation fault detection device of claim 1, wherein the open-ended transformer detection unit further comprises:

the output edge of the isolation transformer is coupled with the primary edge of the voltage regulator, and the secondary edge of the voltage regulator is connected with one end of any branch of any phase of a stator winding of the synchronous generator and used for providing a third alternating current for the branch;

the alternating current collector is positioned on the secondary winding of the open-end transformer and used for collecting the alternating current of the secondary winding of the open-end transformer; the two ends of the open-end transformer can be attached to the surface of the slot part of the stator core to move;

and the third controller is connected with the alternating current collector and used for detecting the insulation fault of the stator winding according to the alternating current collected by the alternating current collector.

8. The synchronous generator insulation fault detection device of claim 7, wherein the secondary side of the voltage regulator is connected to both ends of any branch of any phase of the stator winding of the synchronous generator for supplying a third alternating current of varying amplitude to the branch.

9. A synchronous generator insulation fault detection method, implemented based on the synchronous generator insulation fault detection device according to any one of claims 1 to 8, comprising the steps of:

acquiring the insulation resistance of any branch of any phase in the synchronous generator to the ground;

and determining a branch with a fault according to the size of the insulation resistance, and positioning a bar with the fault in the branch.

10. The synchronous generator insulation fault detection method of claim 9, wherein said determining a branch having a fault based on a magnitude of the insulation resistance and locating a bar having a fault in the branch comprises:

if the insulation resistance is smaller than or equal to a preset value, controlling any one detection unit of the direct current voltage drop detection unit, the voltage impact detection unit or the open-ended transformer detection unit to start to perform fault location detection;

and if the insulation resistance is larger than the preset value, controlling the voltage impact detection unit to start, and after a discharge phenomenon occurs, controlling the open-end transformer detection unit or the direct current voltage drop detection unit to start to perform fault location detection.

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