Large-scale hydro-generator shaft current on-line monitoring device

Abstract

The utility model discloses a large-scale hydro-generator shaft current on-line monitoring device which comprises a support, a grounding carbon brush, a grounding cable, a shaft current transformer and a relay, one end of the support is connected with a generator lower rack, and the other end of the support is close to a generator shaft; the grounding carbon brush is installed at one end, close to the bottom of a generator shaft, of the support, one end of the grounding carbon brush is connected with the generator shaft, the other end of the grounding carbon brush is connected with the grounding cable, the grounding cable is sleeved with the shaft current transformer, and the shaft current transformer is connected with the relay through the grounding cable. According to the on-line monitoring device for the shaft current of the large-scale hydro-generator, electromagnetic interference is avoided in the monitoring process, and the numerical value of the shaft current can be accurately monitored; the shaft current transformer is sleeved on the grounding cable, and the transformer and the carbon brush support are arranged outside the wind tunnel, thereby facilitating installation, overhaul and maintenance.

Description

TECHNICAL FIELD

[0001] The utility model relates to water turbine generator technical field, concretely is a large -scale water turbine generator shaft current on -line monitoring device. BACKGROUND

[0002] Shaft current is related to the safe and stable operation of the unit, and is an important parameter when the water turbine generator is running. With the continuous development and expansion of China's hydropower industry, the problem of shaft current is also emerging, which needs to be solved urgently. Shaft current often leads to bearing bush damage, lubricating oil deterioration and blackening, thrust head, slip rotor electric corrosion and other problems, which seriously affect the safe and stable operation of the unit.

[0003] At present, the majority of shaft current on-line monitoring devices in China are installed on the large shaft (or top shaft) above the rotor, and the transformer sends the induced shaft current to the shaft current relay through secondary wiring. The shaft current relay displays the shaft current and determines whether the shaft current exceeds the alarm value.

[0004] There are some problems in installing the shaft current transformer on the large shaft (or top shaft) above the rotor. First, the shaft current transformer is installed on the shaft, which is affected by the excitation current and other electromagnetic interference, and the secondary induction value of the shaft current transformer will be affected. Second, the shaft current transformer and its support fixing parts are located above the rotating part, which increases the risk of generator sweep bore accident. Third, the shaft current transformer is located above the rotor in the wind tunnel, which is not convenient for maintenance. Fourth, the shaft current transformer is relatively large in size, and the manufacturing cost is relatively high. UTILITY MODEL CONTENTS

[0005] The utility model aims at providing a large -scale water turbine generator shaft current on -line monitoring device to solve the defects mentioned in the above background art.

[0006] To achieve the above object, a large -scale water turbine generator shaft current on -line monitoring device is provided, which comprises: a support, a grounding carbon brush, a grounding cable, a shaft current transformer and a relay, one end of the support is connected with the lower rack of the generator, the other end of the support is close to the generator shaft, the grounding carbon brush is installed at the bottom end of the support close to the generator shaft, one end of the grounding carbon brush is connected with the generator shaft, the other end of the grounding carbon brush is connected with the grounding cable, the shaft current transformer is installed on the grounding cable, and the shaft current transformer is connected with the relay through the grounding cable.

[0007] Further, the support is L-shaped, and the support comprises a bottom plate, a vertical beam and a cross beam, the bottom plate is connected with the lower rack of the generator, the bottom plate is fixedly installed with the vertical beam through a first fastener, the vertical beam is connected with the cross beam through a second fastener, and the grounding carbon brush is installed at the end of the cross beam close to the generator shaft.

[0008] Further, the bottom of the crossbeam near the bottom end of the generator shaft is fixedly installed with a brush box through a screw bolt, and the brush box is used for installing the grounding carbon brush.

[0009] Further, the grounding cable is fastened to the support through a screw.

[0010] Further, the relay comprises an amplifier, the amplifier is connected with a double-channel filter, the double-channel filter is connected with a single-chip microcomputer analysis and judgment controller through an A / D converter respectively, the single-chip microcomputer analysis and judgment controller is connected with a display, the single-chip microcomputer analysis and judgment controller is connected with an upper computer through an RS232 interface, the single-chip microcomputer analysis and judgment controller is connected with an alarm system, and the single-chip microcomputer analysis and judgment controller controls a test current circuit.

[0011] Compared with the prior art, the utility model has the beneficial effects that:

[0012] 1. The application avoids electromagnetic interference in the shaft current online monitoring process, and can accurately monitor the shaft current value.

[0013] 2. The shaft current transformer is sleeved on the grounding cable, and the shaft current transformer and the carbon brush support are both outside the wind tunnel, so that the application is convenient to overhaul and maintain and reduces the risk of a generator sweep bore accident.

[0014] 3. The shaft current transformer is sleeved on the grounding cable, and has the characteristics of small structure, low manufacturing cost and convenient installation. BRIEF DESCRIPTION OF DRAWINGS

[0015] Figure 1 It is a structural schematic diagram of the utility model;

[0016] Figure 2 It is a relay working principle block diagram.

[0017] Marked numbers in the figure: 1, support; 1-1, bottom plate; 1-2, first fastener; 1-3, vertical beam; 1-4, second fastener; 1-5, crossbeam; 2, grounding carbon brush; 3, grounding cable; 4, shaft current transformer; 5, relay; 6, screw; 7, brush box; 8, screw bolt. DETAILED DESCRIPTION

[0018] The technical scheme in the embodiments of the utility model will be described clearly and completely below in combination with the drawings in the embodiments of the utility model. Obviously, the described embodiments are only part of the embodiments of the utility model, rather than all the embodiments. Based on the embodiments in the utility model, all other embodiments obtained by those skilled in the art without creative labor fall within the protection scope of the utility model.

[0019] Please refer toFigure 1 The utility model provides a large -scale water turbine generator shaft current on -line monitoring device, include: support 1, grounding carbon brush 2, grounding cable 3, shaft current mutual -inductor 4 and relay 5.

[0020] Support 1 is L type, including: bottom plate 1-1, vertical beam 1-3 and crossbeam 1-5, bottom plate 1-1 is connected with generator lower rack, avoids electromagnetic interference in the monitoring work process, can accurately monitor shaft current value. Bottom plate 1-1 is fixedly installed vertical beam 1-3 through first fastener 1-2, and the other end of vertical beam 1-3 is connected with one end of crossbeam 1-5 through second fastener 1-4, and the other end of crossbeam 1-5 is close to generator shaft. The support 1 is a steel structure, which supports and fixes the carbon brush.

[0021] The bottom end of crossbeam 1-5 close to generator shaft is fixedly installed through the hinge bolt 8 and a brush box 7, the brush box 7 is used to install the grounding carbon brush 2, one end of the grounding carbon brush 2 is connected with the generator shaft, and the shaft voltage / current is collected.

[0022] The grounding carbon brush 2 is connected with the grounding cable 3, the shaft current mutual -inductor 4 is sleeved on the grounding cable 3, the shaft current is converted into measurable secondary side signal, and the relay 5 is input. The shaft current mutual -inductor 4 is sleeved on the grounding cable 3, and has the characteristics of small structure, low manufacturing cost and convenient installation.

[0023] The shaft current mutual -inductor 4 is connected with the relay 5 through the grounding cable 3, and the current value is compared with the set threshold value, which is used for real -time monitoring.

[0024] In the embodiment, the shaft current mutual -inductor 4 is the through core mutual -inductor of Harbin Huaxin electric power electronic equipment Co. Ltd., and the variable ratio is 400:1.

[0025] In the embodiment, the L-shaped support is used to install the grounding carbon brush 2, the grounding cable 3, the shaft current mutual -inductor 4 and the relay 5 outside the wind tunnel, which is convenient for maintenance and maintenance.

[0026] Because the air gap between the stator and the rotor is not uniform, the magnetic field is asymmetric. When the rotor rotates in the asymmetric magnetic field, alternating magnetic flux intersecting the shaft and axial induced potential, i.e. shaft voltage, are generated at the upper and lower ends of the rotor. The shaft voltage of the water turbine generator set during normal operation is low, generally not more than 10V. If there are two grounding points (grounding point on the rotor, lower end) on the generator shaft, a loop is formed to generate shaft current. According to the structure and concept of the generator, the generator shaft (or lower end shaft) is connected to the generator grounding system through the grounding carbon brush 2 and the grounding cable 3. As long as there are two grounding points on the rotor, the shaft current forms a loop through the generator shaft, the grounding carbon brush 2 and the grounding system, that is, the grounding cable 3 is the only way for the shaft current.

[0027] The grounding cable 3 connects the grounding carbon brush 2, the shaft current transformer 4, and the relay 5 to form a conduction path. When a fault occurs in the unit, the shaft current generated will flow through the grounding carbon brush 2, the grounding cable 3, and the current transformer 4 to send the current to the relay 5 for analysis and monitoring.

[0028] Specifically, the grounding cable 3 is fastened to the bracket 1 by screws 6, which ensures the mechanical stability of the cable and meets the electrical safety requirements.

[0029] like Figure 2 As shown, relay 5 includes an amplifier connected to a dual-channel filter. The dual-channel filter is connected to a microcontroller analysis and judgment controller via an A / D converter. The microcontroller analysis and judgment controller is connected to a display and a host computer via an RS232 interface. The microcontroller analysis and judgment controller is also connected to an alarm system, which has two levels: a primary alarm and a secondary alarm. During monitoring, a primary alarm threshold and a secondary alarm threshold are set. When the primary alarm threshold is exceeded but the secondary alarm threshold is not reached, the primary alarm system sounds an alarm; when the secondary alarm threshold is exceeded, the secondary alarm system sounds an alarm. The microcontroller analysis and judgment controller controls the test current circuit.

[0030] When the unit is running, a shaft current will be generated if a fault occurs. The shaft current passes through the grounding carbon brush 2 and the grounding cable 3. The current transformer 4 sends the induced current to the W1 input terminal of the relay 5. After signal amplification, frequency division filtering and analog-to-digital conversion, the signal is sent to the microcontroller analysis and judgment controller. The microcontroller analysis and judgment controller analyzes, processes, calculates and makes logical judgments, and sends the information to the monitoring system to realize the online monitoring function of displaying shaft current and alarming for excessive shaft current.

[0031] Although embodiments of the present invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the present invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. An online monitoring device for shaft current of a large hydro-generator, comprising: A bracket (1), a grounding carbon brush (2), a grounding cable (3), a shaft current transformer (4), and a relay (5) are characterized in that: one end of the bracket (1) is connected to the lower frame of the generator, and the other end of the bracket (1) is close to the generator shaft; the grounding carbon brush (2) is installed at the bottom end of the bracket (1) near the generator shaft, one end of the grounding carbon brush (2) is connected to the generator shaft, the other end of the grounding carbon brush (2) is connected to the grounding cable (3), the shaft current transformer (4) is mounted on the grounding cable (3), and the shaft current transformer (4) is connected to the relay (5) through the grounding cable (3).

2. The online monitoring device for shaft current of a large hydro-generator according to claim 1, characterized in that: The bracket (1) is L-shaped and includes: a base plate (1-1), a vertical beam (1-3), and a horizontal beam (1-5). The base plate (1-1) is connected to the lower frame of the generator. The base plate (1-1) is fixedly installed with the vertical beam (1-3) by a first fastener (1-2). The vertical beam (1-3) is connected to the horizontal beam (1-5) by a second fastener (1-4). The grounding carbon brush (2) is installed at one end of the horizontal beam (1-5) near the bottom of the generator shaft.

3. The online monitoring device for shaft current of a large hydro-generator according to claim 2, characterized in that: A brush box (7) is fixedly installed at the bottom of the end of the crossbeam (1-5) near the generator shaft by a connecting bolt (8). The brush box (7) is used to install the grounding carbon brush (2).

4. The online monitoring device for shaft current of a large hydro-generator according to claim 1, characterized in that: The grounding cable (3) is fastened to the bracket (1) by screws (6).

5. The online monitoring device for shaft current of a large hydro-generator according to claim 1, characterized in that: The relay (5) includes an amplifier, which is connected to a dual-channel filter. The dual-channel filter is connected to a microcontroller analysis and judgment controller via an A / D converter. The microcontroller analysis and judgment controller is connected to a display and to a host computer via an RS232 interface. The microcontroller analysis and judgment controller is connected to an alarm system and controls the test current circuit.

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