Bulb tubular turbine generator stator grounding protection device and generator

Abstract

The utility model provides a bulb tubular hydraulic generator stator grounding protection device and a generator, and relates to the technical field of hydraulic generators, the device comprises a detection module and a grounding fault positioning analysis module, the detection module and the grounding fault positioning analysis module are in mutual inductance connection; the detection module is used for determining whether the stator has a grounding fault based on the numerical value change of the ampere meter at the primary side of the grounding transformer corresponding to each stator; the ground fault positioning analysis module is used for injecting low-frequency current with different frequencies to each stator when the detection module determines that the stator has the ground fault; and based on a low-frequency current signal detected by a current transformer on the secondary side of the grounding transformer corresponding to each stator, determining the position of the stator with the fault. The device can simply and quickly judge whether a grounding fault occurs, is beneficial to stable operation of a power grid, indirectly improves the power supply reliability, and improves the operation time and efficiency of the bulb tubular hydraulic generator.

Description

Technical Field

[0001] The utility model relates to the technical field of hydro-generators, in particular to a bulb tubular hydro-generator stator grounding protection device and a generator. Background Art

[0002] Because the generator of the bulb-type hydro-turbine generator set and its connected equipment and devices have capacitance to the ground of varying sizes, when a single-phase grounding fault occurs in the generator stator winding, the single-phase grounding fault current flowing through the grounding point is the sum of the capacitive currents generated by the capacitance to the ground of each electrical device. The value of this capacitive current generally ranges from several amperes to tens of amperes.

[0003] When a single-phase ground fault occurs in a generator's stator winding, the arc at the fault point intermittently generates intermittent arc overvoltage, which damages the insulation of the generator's stator winding, causing turn-to-turn or phase-to-phase short circuits, expanding the scope of the fault and, in severe cases, burning the stator core. Similarly, when a single-phase ground fault occurs in a component external to the generator, the arc overvoltage generated at the fault point also damages the insulation of the equipment.

[0004] In the electrical design of newly built hydroelectric power stations using bulb-type hydropower units in China, the generator neutral point is typically grounded using resonant grounding or high-resistance grounding as a ground protection device or insulation monitoring device. When a single-phase ground fault occurs in the stator winding of a single generator in a large number of units, the neutral-point grounding devices of all generators will detect the fault current, signaling the host computer and initiating appropriate operations on the generator circuit. Therefore, when a single-phase ground fault occurs in the stator winding of multiple bulb-type hydropower units in parallel, it is impossible to distinguish the faulty unit, necessitating manual troubleshooting by operators. This impacts the stable and safe operation of the power station and, in severe cases, can even affect the power grid current. Utility Model Content

[0005] In view of this, the purpose of the present invention is to provide a bulb-type tubular turbine generator stator grounding protection device and generator, which can simply and quickly determine whether a ground fault has occurred, thereby contributing to the stable operation of the power grid, indirectly improving power supply reliability and increasing the operating time and efficiency of the bulb-type tubular turbine generator.

[0006] An embodiment of the utility model provides a bulb-type cross-flow hydro-turbine generator stator grounding protection device, which is used to determine the position of a stator having a grounding fault among multiple stators of the hydro-turbine generator; the device includes: a detection module and a grounding fault positioning analysis module, and the detection module and the grounding fault positioning analysis module are mutually inductively connected; the detection module is used to determine whether a stator grounding fault occurs based on the value change of the ammeter on the primary side of the grounding transformer corresponding to each stator; the grounding fault positioning analysis module is used to, when the detection module determines that a stator grounding fault occurs, inject low-frequency currents of different frequencies into each stator; and determine the position of the faulty stator based on the low-frequency current signal detected by the current transformer on the secondary side of the grounding transformer corresponding to each stator.

[0007] In a preferred embodiment of the present invention, the detection module is composed of the primary side of the grounding transformer, a rectifier diode, an ammeter, an inductor, a first load resistor and an industrial frequency current source; the primary side of the grounding transformer is mutually connected to the rectifier diode, and the rectifier diode, ammeter, first load resistor, inductor and industrial frequency current source are connected in sequence.

[0008] In a preferred embodiment of the present invention, the ground fault location and analysis module is composed of a second load resistor, a voltage divider circuit, a low-frequency power supply, and a stator ground protection unit; the stator ground protection unit includes a current transformer and a secondary side of a grounding transformer; the two ends of the secondary side of the grounding transformer are respectively connected to the two ends of the second load resistor, and the voltage divider circuit and the low-frequency power supply are both connected in parallel to the two ends of the second load resistor.

[0009] In a preferred embodiment of the present invention, the voltage divider circuit includes a plurality of voltage divider resistors connected in series.

[0010] In a preferred embodiment of the present invention, the detection module is further configured to perform zeroing processing on the ammeter on the primary side of the grounding transformer corresponding to each stator; if the value of the ammeter on the primary side of the grounding transformer corresponding to the stator changes after the zeroing processing, it is determined that a grounding fault has occurred in the stator.

[0011] In a preferred embodiment of the present invention, the ground fault location analysis module is further configured to determine that no ground fault exists in the stator if the low-frequency current signal detected by the current transformer on the secondary side of the grounding transformer corresponding to the stator is a current of a predetermined frequency corresponding to the stator.

[0012] In a preferred embodiment of the present invention, the ground fault location analysis module is further configured to determine that a ground fault exists in the stator if the current transformer on the secondary side of the grounding transformer corresponding to the stator does not detect a low-frequency current signal.

[0013] In a preferred embodiment of the present invention, the ground fault location analysis module is further used to, when it is determined that a ground fault exists in the stator, determine the location of the stator where the ground fault exists based on the low-frequency current signal detected by the current transformer on the secondary side of the grounding transformer corresponding to other stators except the stator where the ground fault exists.

[0014] An embodiment of the present utility model further provides a bulb tubular hydro-turbine generator, comprising a generator system and the above-mentioned bulb tubular hydro-turbine generator stator grounding protection device.

[0015] The embodiments of the present invention bring the following beneficial effects:

[0016] The present invention provides a stator grounding protection device for a bulb-type hydro-turbine generator and a generator. The device includes a detection module and a grounding fault location analysis module. The detection module and the grounding fault location analysis module are interconnected. The detection module determines whether a stator grounding fault exists based on the value change of the ammeter on the primary side of each stator's corresponding grounding transformer. When the detection module determines that a stator grounding fault exists, the grounding fault location analysis module injects low-frequency currents of different frequencies into each stator. Based on the low-frequency current signals detected by the current transformer on the secondary side of each stator's corresponding grounding transformer, the location of the faulty stator is determined. This device quickly and easily determines whether a grounding fault has occurred, contributing to the stable operation of the power grid, indirectly improving power supply reliability, and increasing the operating time and efficiency of the bulb-type hydro-turbine generator.

[0017] Other features and advantages of the present disclosure will be set forth in the following description, or some features and advantages may be inferred or unambiguously determined from the description, or may be learned by practicing the above-mentioned technology of the present disclosure.

[0018] In order to make the above-mentioned objectives, features and advantages of the present disclosure more obvious and easy to understand, preferred embodiments are given below and described in detail with reference to the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] In order to more clearly illustrate the specific implementation methods of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the specific implementation methods or the description of the prior art. Obviously, the drawings described below are some implementation methods of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0020] Figure 1 A structural diagram of a bulb tubular hydro-generator stator grounding protection device provided in an embodiment of the utility model;

[0021] Figure 2 A structural diagram of a detection module provided in an embodiment of the present utility model;

[0022] Figure 3 A structural diagram of a ground fault location analysis module provided by an embodiment of the present utility model;

[0023] Figure 4 A schematic diagram of the overall structure of a bulb tubular hydro-generator stator grounding protection device provided by an embodiment of the utility model;

[0024] Figure 5 This is a structural diagram of a bulb-type tubular hydro-generator provided in an embodiment of the utility model.

[0025] Diagram:

[0026] 10-Detection module; 20-Ground fault location analysis module; 11-Primary side of grounding transformer; 12-Rectifier diode; A-Ammeter; 13-Inductor; 14-First load resistor; 15-Power frequency current source; 16-Mutual inductor; Rn-Second load resistor; 21-Voltage divider circuit; 22-Low frequency power supply; 23-Stator ground protection unit; Current transformer I GO -Current transformer; U GO -Secondary side of grounding transformer; 30-Generator system; G-Generator; 31-Step-up transformer; 32-High-voltage side bus. DETAILED DESCRIPTION

[0027] To make the purpose, technical solutions, and advantages of the embodiments of the present invention more clear, the technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the embodiments described are only part of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts shall fall within the scope of protection of the present invention.

[0028] Because the generator of the bulb-type hydro-turbine generator set and its connected equipment and devices have capacitance to the ground of varying sizes, when a single-phase grounding fault occurs in the generator stator winding, the single-phase grounding fault current flowing through the grounding point is the sum of the capacitive currents generated by the capacitance to the ground of each electrical device. The value of this capacitive current generally ranges from several amperes to tens of amperes.

[0029] When a single-phase ground fault occurs in a generator's stator winding, the arc at the fault point intermittently generates intermittent arc overvoltage, which damages the insulation of the generator's stator winding, causing turn-to-turn or phase-to-phase short circuits, expanding the scope of the fault and, in severe cases, burning the stator core. Similarly, when a single-phase ground fault occurs in a component external to the generator, the arc overvoltage generated at the fault point also damages the insulation of the equipment.

[0030] In the electrical design of newly built hydroelectric power stations using bulb-type hydropower units in China, the generator neutral point is typically grounded using resonant grounding or high-resistance grounding as a ground protection device or insulation monitoring device. When a single-phase ground fault occurs in the stator winding of a single generator in a large number of units, the neutral-point grounding devices of all generators will detect the fault current, signaling the host computer and initiating appropriate operations on the generator circuit. Therefore, when a single-phase ground fault occurs in the stator winding of multiple bulb-type hydropower units in parallel, it is impossible to distinguish the faulty unit, necessitating manual troubleshooting by operators. This impacts the stable and safe operation of the power station and, in severe cases, can even affect the power grid current.

[0031] To address these issues, a bulb-type tubular hydro-turbine generator stator ground fault protection device is urgently needed. This device can quickly detect the specific generator stator winding where a ground fault has occurred. This device can contribute to the stable operation of the power grid, reduce grid failures, or even provide support to the grid. This can indirectly improve power supply reliability. Furthermore, the bulb-type tubular hydro-turbine generator stator ground fault protection device will effectively increase the operating time and efficiency of hydro-generator units.

[0032] Based on this, the present invention provides a stator grounding protection device for a bulb-type hydro-turbine generator and a generator. The device includes a detection module and a grounding fault location analysis module. The detection module and the grounding fault location analysis module are interconnected. The detection module determines whether a stator grounding fault exists based on the value change of the ammeter on the primary side of the grounding transformer corresponding to each stator. When the detection module determines that a stator grounding fault exists, the grounding fault location analysis module injects low-frequency currents of different frequencies into each stator. Based on the low-frequency current signals detected by the current transformer on the secondary side of the grounding transformer corresponding to each stator, the location of the faulty stator is determined. This device quickly and easily determines whether a grounding fault has occurred, contributing to the stable operation of the power grid, indirectly improving power supply reliability, and increasing the operating time and efficiency of the bulb-type hydro-turbine generator.

[0033] To facilitate understanding of this embodiment, a bulb tubular hydro-generator stator grounding protection device disclosed in an embodiment of the present utility model is first introduced in detail.

[0034] Example 1

[0035] The embodiment of the utility model provides a bulb tubular hydro-generator stator grounding protection device, which is used to determine the position of a stator having a grounding fault among multiple stators of the hydro-generator. Figure 1 This is a structural diagram of a bulb-type tubular hydro-generator stator grounding protection device provided by the embodiment of the utility model. Figure 1As shown, the bulb tubular hydro-generator stator grounding protection device may include the following structure:

[0036] The detection module 10 and the ground fault location analysis module 20 are mutually inductively connected.

[0037] Specifically, the detection module 10 is used to determine whether a stator grounding fault occurs based on the value change of the ammeter on the primary side of the grounding transformer corresponding to each stator.

[0038] For changes in the ammeter value, the ammeter value may be adjusted to zero to ensure that under normal circumstances, there is no abnormality in the current on the primary side of the grounding transformer, thereby improving the accuracy of detection.

[0039] It should be noted that when a stator fault occurs, the current will flow to the ground, then pass through the grounding transformer and produce a mutual induction effect with the detection module, causing the ammeter value to change. Therefore, it can be determined whether there is a stator grounding fault.

[0040] Specifically, the ground fault location analysis module 20 is used to, when the detection module 10 determines that a stator ground fault exists, inject low-frequency currents of different frequencies into each stator; and determine the location of the faulty stator based on the low-frequency current signal detected by the current transformer on the secondary side of the grounding transformer corresponding to each stator.

[0041] It should be noted that, since the low-frequency current signals corresponding to low-frequency currents of different frequencies are different, different stators can be distinguished by injecting low-frequency currents of different frequencies.

[0042] The stator grounding protection device for a bulb-type hydro-turbine generator provided by the present invention can determine whether a stator ground fault has occurred based on the numerical changes in the ammeter on the primary side of each stator's corresponding grounding transformer through a detection module. When the detection module determines that a stator ground fault has occurred, the ground fault location analysis module injects low-frequency currents of different frequencies into each stator. The location of the faulty stator is determined based on the low-frequency current signals detected by the current transformer on the secondary side of each stator's corresponding grounding transformer. This device quickly and easily determines whether a ground fault has occurred, contributing to the stable operation of the power grid, indirectly improving power supply reliability, and increasing the operating time and efficiency of the bulb-type hydro-turbine generator.

[0043] Example 2

[0044] The embodiment of the present utility model further provides a detection module; the detection module is implemented on the basis of the bulb tubular hydro-generator stator grounding protection device mentioned in the above embodiment.

[0045] Figure 2 This is a structural diagram of a detection module provided by an embodiment of the present utility model. Figure 2 As shown, the detection module 10 may include: a grounding transformer primary side 11, a rectifier diode 12, an ammeter A, an inductor 13, a first load resistor 14 and an industrial frequency current source 15; the grounding transformer primary side 11 is mutually connected to the rectifier diode 12 through a mutual inductor 16, and the rectifier diode 12, the ammeter A, the first load resistor 14, the inductor and the industrial frequency current source 15 are connected in sequence.

[0046] The grounding transformer is a double-winding grounding transformer, and the primary side of the grounding transformer, ie, the primary side 11 of the grounding transformer, is located in the detection module.

[0047] When a ground fault occurs in a stator, a closed loop is formed with the ground by the stator. The current flows to the ground and then through the grounding transformer, generating a mutual inductance effect with the inductor, thereby changing the value of the ammeter A.

[0048] In order to ensure the accuracy of the detection and avoid detection in abnormal situations, the detection module is also used to zero the ammeter A on the primary side 11 of the grounding transformer corresponding to each stator. If the value of the ammeter A on the primary side 11 of the grounding transformer corresponding to the stator changes after the zeroing process, it is determined that a stator grounding fault has occurred.

[0049] The power supply can be provided by the industrial frequency current source 15 , and the ammeter A is adjusted to zero to keep the value of the ammeter A at zero.

[0050] The detection module provided in the embodiment of the present utility model can improve the accuracy of detection by zeroing the ammeter, and can simply and quickly determine whether a stator ground fault has occurred based on the change in the ammeter value, thereby contributing to the stable operation of the power grid, indirectly improving the power supply reliability and increasing the operating time and efficiency of the bulb-type hydro-turbine generator.

[0051] Example 3

[0052] The present invention also provides a ground fault location analysis module, which is implemented based on the bulb tubular hydro-generator stator ground protection device mentioned in the above embodiment.

[0053] Figure 3 This is a structural diagram of a ground fault location analysis module provided by an embodiment of the present utility model. Figure 3 As shown, the ground fault location analysis module 20 may include: a second load resistor Rn, a voltage divider circuit 21, a low-frequency power supply 22 and a stator ground protection unit 23; the stator ground protection unit 23 includes a current transformer and a ground transformer secondary side UGO ; Grounding transformer secondary side U GO The two ends of are respectively connected to the two ends of the second load resistor Rn, and the voltage divider circuit 21 and the low-frequency power supply 22 are both connected in parallel to the two ends of the second load resistor Rn.

[0054] The voltage divider circuit 21 includes a plurality of voltage divider resistors connected in series.

[0055] Among them, the ground fault location analysis module is also used to, if the stator corresponding grounding transformer secondary side U GO If the low-frequency current signal detected by the current transformer is a current of a predetermined frequency corresponding to the stator, it is determined that there is no ground fault in the stator.

[0056] Among them, if the secondary side of the grounding transformer corresponding to the stator is U GO If the low-frequency current signal is not detected by the current transformer, it is determined that there is a ground fault in the stator.

[0057] Wherein, when it is determined that there is a ground fault in the stator, the secondary side U of the grounding transformer corresponding to other stators except the stator with the ground fault is GO The low-frequency current signal detected by the current transformer is used to determine the location of the stator where the ground fault exists.

[0058] It should be noted that under normal circumstances, the current transformer can only detect the signal of its own low-frequency current. When a ground fault occurs in a stator, the neutral point potential of the stator is not zero, and a loop will be formed with the ground. The injected low-frequency current will flow from the faulty stator to the ground, and then flow through the ground to the primary side of the grounding transformer corresponding to other stators. Through the mutual inductance effect, the secondary side U GO The current transformer will detect the low-frequency current signal corresponding to the faulty stator, thereby determining the location of the stator where the ground fault occurred.

[0059] The ground fault location analysis module provided in the embodiment of the present invention can distinguish the stators by injecting low-frequency current signals of different frequencies into each stator, and locate the faulty stator based on the low-frequency current signals, thereby contributing to the stable operation of the power grid, indirectly improving the power supply reliability and increasing the operating time and efficiency of the bulb-type hydro-turbine generator.

[0060] For ease of understanding, Figure 4 This is a schematic diagram of the overall structure of a bulb-type tubular hydro-generator stator grounding protection device provided by the embodiment of the utility model. Figure 4 As shown, the bulb tubular turbine generator stator grounding protection device is connected to the generator system.

[0061] Example 4

[0062] The embodiment of the present utility model further provides a bulb tubular hydro-turbine generator, which is implemented on the basis of the bulb tubular hydro-turbine generator stator grounding protection device mentioned in the above embodiment.

[0063] Figure 5 The structure diagram of a bulb-type hydro-generator provided by the embodiment of the utility model is as follows: Figure 5 As shown, the bulb tubular turbine generator may include a generator system and the bulb tubular turbine generator stator grounding protection device mentioned in the above embodiment.

[0064] The generator system 30 may include a generator G, a step-up transformer 31 and a high-voltage side bus 32 connected in sequence.

[0065] It should be noted that the step-up transformer 31 and the high-voltage side bus 32 are connected to the generator G and are important components of the generator system 30. However, they do not supply power to the generator G. Instead, they step up the voltage of the electric energy generated by the generator G and transmit it to the power grid. During the power transmission process, the generator G first outputs the power to the step-up transformer 31. After the step-up transformer 31 increases the voltage, the power is transmitted to the power grid or load through the high-voltage side bus 32.

[0066] Units described as separate components may or may not be physically separate, and components shown as units may or may not be physical units, that is, they may be located in one place or distributed across multiple network units. Some or all of these units may be selected to achieve the purpose of this embodiment according to actual needs.

[0067] Finally, it should be noted that the above-described embodiments are only specific implementation methods of the present invention, which are used to illustrate the technical solutions of the present invention, rather than to limit them. The scope of protection of the present invention is not limited thereto. Although the present invention has been described in detail with reference to the above-mentioned embodiments, those skilled in the art should understand that any person skilled in the art can modify or easily conceive of changes to the technical solutions described in the above-mentioned embodiments within the technical scope disclosed by the present invention, or replace some of the technical features therein with equivalents. Such modifications, changes, or replacements do not deviate from the spirit and scope of the technical solutions of the embodiments of the present invention, and should be included in the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be based on the scope of protection of the claims.

Claims

1. A bulb tubular hydro-generator stator grounding protection device, characterized in that: Used to determine the position of a stator having a ground fault among multiple stators of a hydro-generator; The device comprises: a detection module and a ground fault location analysis module, wherein the detection module is mutually inductively connected to the ground fault location analysis module; The detection module is used to determine whether a stator grounding fault occurs based on the value change of the ammeter on the primary side of the grounding transformer corresponding to each stator; The ground fault location analysis module is used to, when the detection module determines that a stator ground fault occurs, inject low-frequency currents of different frequencies into each stator; and determine the location of the faulty stator based on the low-frequency current signal detected by the current transformer on the secondary side of the grounding transformer corresponding to each stator; The detection module is composed of a grounding transformer primary side, a rectifier diode, an ammeter, an inductor, a first load resistor, and a power frequency current source; the grounding transformer primary side is mutually connected to the rectifier diode, and the rectifier diode, the ammeter, the first load resistor, the inductor, and the power frequency current source are connected in sequence; The ground fault location and analysis module consists of a second load resistor, a voltage divider circuit, a low-frequency power supply, and a stator ground protection unit; the stator ground protection unit includes a current transformer and a secondary side of a grounding transformer; the two ends of the secondary side of the grounding transformer are respectively connected to the two ends of the second load resistor, and the voltage divider circuit and the low-frequency power supply are both connected in parallel to the two ends of the second load resistor.

2. The stator grounding protection device of the bulb tubular hydro-generator according to claim 1 is characterized in that: The voltage dividing circuit includes a plurality of voltage dividing resistors connected in series.

3. The stator grounding protection device of the bulb tubular hydro-generator according to claim 1 is characterized in that: The detection module is further configured to perform zero adjustment on the ammeter on the primary side of the grounding transformer corresponding to each stator; if the value of the ammeter on the primary side of the grounding transformer corresponding to the stator changes after the zero adjustment, it is determined that a grounding fault has occurred in the stator.

4. The stator grounding protection device of the bulb tubular hydro-generator according to claim 3 is characterized in that: The ground fault location analysis module is further configured to determine that no ground fault exists in the stator if the low-frequency current signal detected by the current transformer on the secondary side of the ground transformer corresponding to the stator is a current of a predetermined frequency corresponding to the stator.

5. The stator grounding protection device of the bulb tubular hydro-generator according to claim 4 is characterized in that: The ground fault location analysis module is further configured to determine that a ground fault exists in the stator if the current transformer on the secondary side of the grounding transformer corresponding to the stator does not detect a low-frequency current signal.

6. The stator grounding protection device of the bulb tubular hydro-generator according to claim 5 is characterized in that: The ground fault location analysis module is further configured to, when it is determined that a ground fault exists in the stator, determine the location of the stator where the ground fault exists based on low-frequency current signals detected by current transformers on the secondary sides of grounding transformers corresponding to stators other than the stator where the ground fault exists.

7. A bulb tubular hydro-turbine generator, characterized in that: The invention comprises a generator system and a stator grounding protection device of a bulb tubular hydro-turbine generator according to any one of claims 1 to 6.

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