Device for quickly positioning grounding fault of multi-branch winding of hydroelectric generating set
By designing a rapid positioning device for multi-branch winding grounding faults for hydropower sets, using controllers and contactors to apply variable frequency AC power to the windings, the problem of difficult to quickly position the grounding fault of multi-branch windings of hydropower sets is solved, and the problem of difficult to quickly position the grounding fault of multi-branch windings of hydropower sets is realized. Quick positioning and fault line rod calculation reduce maintenance time and economic losses, and improve energy supply and grid system security.
Patent Information
- Application Number
- CN202420905759.3
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- Filing Date
- 2024-04-28
- Publication Date
- 2025-02-18
- Estimated Expiration
- 2034-04-28
AI Technical Summary
The grounding failure of the multi-branch winding of hydroelectric generator sets is difficult to quickly locate, resulting in long shutdown and maintenance time, causing economic losses and adverse effects on energy supply and power grid system safety.
A device for rapid positioning of grounding faults of multi-branch windings of hydropower sets is designed. The controller controls the contactor and current clip to apply variable frequency AC power to different points of the windings, determine the fault branch and calculate the position of the fault line rod.
It realizes rapid positioning of the grounding fault of the multi-branch winding of hydroelectric generator sets, saving maintenance time, reducing economic losses, and improving energy supply and grid system safety.
Smart Images
Figure CN222506536U_ABST
Abstract
Description
Technical Field
[0001] The utility model relates to the technical field of water turbine detection, in particular to a device for quickly locating grounding faults of multi-branch windings of a hydroelectric generator set. Background Art
[0002] The installed capacity of a single hydropower generating unit is as high as one million kilowatts, with a high voltage level and many fully insulated winding branches. Once a grounding fault occurs, it is difficult to quickly and intuitively find the grounding point because the winding is fully insulated, resulting in a long shutdown and maintenance period, which in turn causes great economic losses and has an adverse impact on energy supply and power grid system security.
[0003] In the past, when dealing with similar grounding faults, it was often necessary to remove the external slot wedges and rotor components of the unit's windings for manual carpet-style fault troubleshooting, which was time-consuming, costly, and inefficient, and even required destroying the insulation of the external part of the winding to find the grounding point.
[0004] According to the previous experience of similar fault maintenance of hydroelectric generator sets, when a shutdown caused by a ground fault occurs, it is necessary to first measure the insulation condition of the three-phase windings with a high-voltage insulation resistance meter to determine the faulty phase. However, since the branch windings are connected by welding through the riser, it is impossible to directly determine the specific faulty branch, let alone the specific location of the faulty wire rod. To find the fault location, it is necessary to manually check the insulation integrity of the exposed part of the wire rod end. If the end fault is eliminated, it is necessary to continue to check the wire rod fault in the slot. At this time, the generator cover and individual rotor poles need to be removed, and the insulation of the wire rod surface in the core slot part needs to be checked manually. If the fault point cannot be determined, it is necessary to remove the wire rod slot wedges one by one and continue to check the insulation until the fault point is found. There are hundreds of core slots. The longer the inspection time, the greater the power generation loss. How to quickly locate the fault point is one of the technical problems that power plants urgently need to solve. Summary of the invention
[0005] The technical problem to be solved by the utility model is to provide a device for quickly locating grounding faults of multi-branch windings of a hydroelectric generator set, which can conveniently and quickly detect and output the grounding faults of the branch windings.
[0006] In order to solve the above technical problems, the technical solution adopted by the utility model is:
[0007] A device for quickly locating grounding faults of multi-branch windings of a hydroelectric generator set comprises a first variable frequency AC power supply and a second variable frequency AC power supply, wherein one side of the first variable frequency AC power supply is grounded, and the other side is electrically connected to a first current clamp and a second current clamp through a first contactor KM1 and a second contactor KM2, respectively; the first current clamp is used to connect the center point of a winding phase to be detected, and the second current clamp is used to connect to the ends of each branch of the winding phase to be detected; the second variable frequency AC power supply is used to connect to the beginning ends of each branch of the winding phase to be detected through a third contactor KM3 and a third current clamp; the first contactor KM1, the second contactor KM2 and the third contactor KM3 are controlled to be turned on and off by a detection controller; the detection controller is communicatively connected to a first open-type current transformer and a second open-type current transformer; the first open-type current transformer and the second open-type current transformer are respectively used to detect the beginning and end currents of each branch of the winding phase to be detected.
[0008] The output end of the detection controller is connected to a control relay, and the control relay controls the on and off of the first contactor KM1, the second contactor KM2 and the third contactor KM3.
[0009] The first open-type current transformer and the second open-type current transformer are electrically connected to the analog quantity module, and the analog quantity module is communicatively connected to the detection controller.
[0010] The input terminal of the detection controller is electrically connected to the operation button.
[0011] The detection controller is communicatively connected with the human-machine interaction screen.
[0012] The first contactor KM1 and the second contactor KM2 are interlocked and controlled by a control relay.
[0013] The utility model provides a device for quickly locating grounding faults of multi-branch windings of a hydroelectric generator set. By controlling a controller in combination with a contactor to apply an AC variable frequency power supply to different points of the winding branches, the location of the faulty branch of the winding can be determined. The calculation result of the faulty wire rod can also be directly output, which is convenient for quickly locating the grounding fault of the winding. BRIEF DESCRIPTION OF THE DRAWINGS
[0014] The utility model is further described below in conjunction with the accompanying drawings and embodiments:
[0015] Figure 1 This is a schematic diagram of the device connection circuit of the utility model;
[0016] Figure 2 This is the electrical schematic diagram of the detection controller of the utility model;
[0017] Figure 3 This is a schematic diagram of a grounding fault in the utility model;
[0018] Figure 4 This is a schematic diagram of the fault detection of the utility model embodiment Figure 1 ;
[0019] Figure 5 This is a schematic diagram of the fault detection of the utility model embodiment Figure 2 ;
[0020] Figure 6 This is a schematic diagram of the fault detection of the utility model embodiment Figure 3 .
[0021] In the figure: first variable frequency AC power supply 1, first open type current transformer 2, second open type current transformer 3, second variable frequency AC power supply 4, first current clamp 5, second current clamp 6, third current clamp 7, detection controller 8, analog module 9, control relay 10, operation button 11, human-computer interaction screen 12, first contactor KM1, second contactor KM2, third contactor KM3. DETAILED DESCRIPTION
[0022] A device for quickly locating a multi-branch winding grounding fault of a hydroelectric generator set comprises a first variable frequency AC power supply 1 and a second variable frequency AC power supply 4. One side of the first variable frequency AC power supply 1 is grounded, and the other side is electrically connected to a first current clamp 5 and a second current clamp 6 through a first contactor KM1 and a second contactor KM2, respectively. The first current clamp 5 is used to connect the center point of the winding phase to be detected, and the second current clamp 6 is used to connect to the ends of each branch of the winding phase to be detected. The second variable frequency AC power supply 4 is used to connect to the beginning of each branch of the winding phase to be detected through a third contactor KM3 and a third current clamp 7. The first contactor KM1, the second contactor KM2 and the third contactor KM3 are controlled by a detection controller 8 to be turned on and off. The detection controller 8 is communicatively connected to a first open-type current transformer 2 and a second open-type current transformer 3. The first open-type current transformer 2 and the second open-type current transformer 3 are respectively used to detect the beginning and end currents of each branch of the winding phase to be detected.
[0023] Through the control of the detection controller 8, the first contactor KM1 is first controlled to be turned on. The circuit is as follows Figure 4 As shown in , by detecting whether the current magnitude and direction at the beginning and end of each branch are the same, it can be determined whether the current branch is faulty, and then the second current clamp 6 and the third current clamp 7 are clamped at the beginning and end of the faulty branch respectively, and the second contactor KM2 and the third contactor KM3 are controlled to be turned on. The circuit structure is as follows Figure 5 As shown in Figure 6As shown in the figure, the first open-type current transformer 2 and the second open-type current transformer 3 respectively detect the stable current at the beginning and the stable current at the end of the fault branch, and then the faulty wire rod can be known by calculation. The process control can be carried out by the detection controller 8, and the calculation result can also be output by the detection controller 8.
[0024] The output end of the detection controller 8 is connected to the control relay 10, and the control relay 10 controls the on and off of the first contactor KM1, the second contactor KM2 and the third contactor KM3.
[0025] The first open-type current transformer 2 and the second open-type current transformer 3 are electrically connected to the analog quantity module 9 , and the analog quantity module 9 is communicatively connected to the detection controller 8 .
[0026] Through the open structure of the first open-type current transformer 2 and the second open-type current transformer 3, detection can be switched between the winding branches, so that each branch can be switched and detected manually, saving the number of transformers. The detection analog quantity of the current transformer is converted into a digital quantity through the analog quantity module 9 and then transmitted to the detection controller 8.
[0027] The input end of the detection controller 8 is electrically connected to the operation button 11 .
[0028] The detection controller 8 is connected to the human-machine interaction screen 12 for communication.
[0029] The current detection stage can be input through the human-machine interaction screen 12, and the detection controller 8 controls the corresponding contactor to be turned on, and the confirmation control and emergency stop are performed through the operation button 11.
[0030] The first contactor KM1 and the second contactor KM2 are interlocked and controlled by the control relay 10 .
[0031] Example:
[0032] The present invention is used to detect winding faults. The embodiments are further described in combination with the accompanying drawings and data examples.
[0033] 1. A single hydro-turbine generator in a power station has a capacity of 850,000 kilowatts and a rated current of 22KA. The generated current is sent out through three phases ABC, and the single-phase winding has 8 branches. Figure 1 As shown, each branch is welded by 64 wire rods, and the branches are connected together by a lifting base and are inseparable. When the unit shuts down, the unit's relay protection shows that a single-phase grounding fault occurs in phase A, but it is impossible to accurately locate the specific location of a branch where the grounding fault occurs.
[0034] 2. When the unit relay protection indicates that a single-phase grounding fault has occurred in phase A, disconnect all soft connections between the generator phase A outlet and the phase A neutral point.
[0035] 3. Such as Figure 2 As shown, an external variable frequency AC power supply is connected to the neutral point of phase A. By using this device, the detection controller 8 controls the first contactor KM1, and the current is detected by the first open-type current transformer 2 and the second open-type current transformer at the beginning and end of each branch respectively. Each time a branch is detected, the current branch number is confirmed through the human-computer interaction screen 12. The detection controller 8 records the current two transformer detection values as the starting and terminal currents of the current branch, and measures the stable current value of the current at the end of each branch by rising the voltage from zero.
[0036] 4. Record the current phasor at the stable starting end of each branch s1 , s2 … s8 , the terminal current phasor e1 , e2 … e8 , and determine whether the following formula is true:
[0037] sn = en (n=1…8);
[0038] 5. If the above formula is true, that is, the magnitude and direction of the current at the beginning and the end are the same, then there is no ground fault in the branch; if the formula is not true, it is determined that there is a ground fault in the branch. This implementation case assumes that the faulty branch is branch 1.
[0039] 6. If Figure 3 As shown, the beginning and end of the first branch are connected to an external variable frequency AC power supply, that is, the first contactor KM1 is controlled to be disconnected, the second contactor KM2 and the third contactor KM3 are connected, the power is 100KW, the frequency is 50HZ, the output voltage is U=100V, and the optical fiber current transformer 2 at the beginning and end of the branch is retained; the stable beginning current value of the first branch is recorded =4.17A, record the stable end current value of the first branch =4.98A, the value is automatically recorded by the controller in the current branch record.
[0040] 7. Such as Figure 4 As shown, the impedance value from the beginning of the first branch to the faulty wire rod is Z sgc1 The impedance value from the end of the first branch to the faulty wire rod is Z egc1 The ground impedance value is Z FThe equivalent impedance value of the remaining branches (2nd to 8th branches) of the fault phase is Z sum . Then the following relationship is obtained:
[0041] U=Isgc1Z sgc1 + (Isgc1+Iegc1) Z F ;
[0042] U=Iegc1Z egc1 + (Isgc1+Iegc1) Z F ;
[0043] The impedance value Z from the first end to the faulty wire rod can be calculated. sgc1 The proportional relationship Z between the impedance value at the end of the first branch and the faulty wire rod egc1 :
[0044] ;
[0045] .
[0046] 8. Since the material and size parameters of each wire rod are the same, their impedance values are equal. Based on the above impedance value ratio, the location value of the first fault wire rod GC can be calculated = =30, the calculation result can be displayed on the human-computer interaction screen.
[0047] 9. Starting from the end of the first branch, the GC=30th wire rod is the faulty wire rod.
Claims
1. A device for quickly locating ground faults of multi-branch windings of a hydroelectric generator set, characterized by: The invention comprises a first variable frequency AC power source (1) and a second variable frequency AC power source (4). One side of the first variable frequency AC power source (1) is grounded, and the other side is electrically connected to a first current clamp (5) and a second current clamp (6) through a first contactor KM1 and a second contactor KM2, respectively. The first current clamp (5) is used to connect the center point of a winding phase to be detected, and the second current clamp (6) is used to connect to the ends of each branch of the winding phase to be detected. The second variable frequency AC power source (4) is used to connect to the beginning ends of each branch of the winding phase to be detected through a third contactor KM3 and a third current clamp (7). The first contactor KM1, the second contactor KM2 and the third contactor KM3 are controlled to be turned on and off by a detection controller (8). The detection controller (8) is communicatively connected to a first open-type current transformer (2) and a second open-type current transformer (3). The first open-type current transformer (2) and the second open-type current transformer (3) are used to detect the beginning and end currents of each branch of the winding phase to be detected, respectively.
2. The device for quickly locating a multi-branch winding grounding fault of a hydroelectric generator set according to claim 1 is characterized in that: The output end of the detection controller (8) is connected to the control relay (10), and the control relay (10) controls the on and off of the first contactor KM1, the second contactor KM2 and the third contactor KM3.
3. The device for quickly locating a multi-branch winding grounding fault of a hydroelectric generator set according to claim 2 is characterized in that: The first open-type current transformer (2) and the second open-type current transformer (3) are electrically connected to an analog quantity module (9), and the analog quantity module (9) is communicatively connected to a detection controller (8).
4. The device for quickly locating a multi-branch winding grounding fault of a hydroelectric generator set according to claim 3 is characterized in that: The input end of the detection controller (8) is electrically connected to the operation button (11).
5. The device for quickly locating ground faults of multi-branch windings of a hydroelectric generator set according to claim 4 is characterized in that: The detection controller (8) is communicatively connected to the human-machine interaction screen (12).
6. The device for quickly locating ground faults of multi-branch windings of a hydroelectric generator set according to claim 5, characterized in that: The first contactor KM1 and the second contactor KM2 are interlocked and controlled by a control relay (10).