On-line monitoring device for shaft voltage and shaft current

Abstract

The utility model discloses an on-line monitoring device for shaft voltage and shaft current. The on-line monitoring device comprises a junction box, an electric brush monitoring module, a shaft voltage and shaft current measuring device, a straight-through current transformer, an excitation end shaft voltage measuring carbon brush and a steam end shaft current measuring carbon brush, the shaft voltage and shaft current measuring device is electrically connected with the electric brush monitoring module; the straight-through current transformer is connected with the axial voltage and axial current measuring device through the connection point of the secondary high end of the transformer output line and the connection point of the secondary high end of the transformer output line. The excitation end shaft voltage measuring carbon brush is electrically connected with the junction box; and the steam end shaft current measuring carbon brush is electrically connected with the straight-through current transformer. According to the utility model, the shaft voltage and the shaft current can be continuously measured on line by adopting the shaft voltage and shaft current measuring device, a control and setting range is provided, and real-time shaft voltage and shaft current data can be reflected in real time through the digital display meter.

Description

Technical Field

[0001] The utility model relates to the field of shaft voltage and shaft current online monitoring devices, in particular to a shaft voltage and shaft current online monitoring device. Background Art

[0002] At present, large steam turbine generators will generate shaft voltage during normal operation. If effective preventive measures are not taken or the preventive measures fail, it will lead to serious consequences of bearing burns. Domestic generator manufacturers have standardized designs to eliminate the hazards of shaft voltage, that is, to install a large shaft grounding carbon brush on the outside of the bearing near the turbine end of the generator shaft, and to install a reliable insulating gasket on the bearing base near the excitation end of the generator shaft. As long as these devices work correctly, they can solve the problem of large steam turbine generator rotor shaft voltage being too high and causing damage to the generator bearing. Unfortunately, the actual operation of many domestic power plants shows that large steam turbine generator bearing burns still occur from time to time. The main reason is the lack of effective online monitoring methods to ensure that these preventive measures are in a reliable working state. At present, the domestic shaft voltage and shaft current measurement device can only achieve real-time monitoring and alarm functions of shaft voltage and shaft current. It lacks brush monitoring and cannot reflect real-time shaft voltage and shaft current data in real time. Summary of the invention

[0003] In view of the above problems, the utility model proposes an online monitoring device for shaft voltage and shaft current, which solves the defects that the existing shaft voltage and shaft current measuring devices can only perform real-time monitoring and alarm functions of shaft voltage and shaft current, lack brush monitoring, and cannot reflect real-time shaft voltage and shaft current data in real time.

[0004] The technical solution adopted by the utility model is as follows:

[0005] A shaft voltage and shaft current online monitoring device comprises: a junction box, a brush monitoring module, a shaft voltage and shaft current measuring device, a through-type current transformer, an excitation end shaft voltage measuring carbon brush and a steam end shaft current measuring carbon brush; the shaft voltage and shaft current measuring device is electrically connected to the brush monitoring module; the through-type current transformer is connected to the shaft voltage and shaft current measuring device via a connection point of a secondary high end of a transformer output line and a connection point of a secondary high end of a transformer output line; the excitation end shaft voltage measuring carbon brush is electrically connected to the junction box; the steam end shaft current measuring carbon brush is electrically connected to the through-type current transformer.

[0006] The utility model adopts a shaft voltage and shaft current measuring device to continuously measure shaft voltage and shaft current online, and provides a control and setting range, and reflects real-time shaft voltage and shaft current data in real time through a digital display.

[0007] Optionally, the grounding plate is connected to the junction box via a wiring line, and the lead-out wire of the through-type current transformer is connected to the grounding plate.

[0008] Optionally, the brush monitoring module includes a DI / DO signal detection alarm module, a display module and a TCS / DCS system.

[0009] Optionally, the shaft voltage and shaft current measuring device transmits signals to the DI / DO signal detection alarm module, the display module and the TCS / DCS system through a transmitter.

[0010] Optionally, the display module includes a shaft voltage display instrument and a shaft current display instrument.

[0011] Optionally, the shaft voltage and shaft current online monitoring device also includes a cabinet; the DI / DO signal detection alarm module and the shaft voltage and shaft current measuring device are both installed on the cabinet.

[0012] Optionally, the shaft voltage and shaft current measuring device is installed on the upper part of the DI / DO signal detection and alarm module.

[0013] Optionally, the transmitter is installed on the upper part of the shaft voltage and shaft current measuring device.

[0014] Optionally, the shaft voltage and shaft current online monitoring device further includes a current relay, and the current relay is arranged in parallel with the transmitter.

[0015] Optionally, the shaft voltage and shaft current online monitoring device further comprises a manual test button, which detects whether the grounding of the excitation end shaft voltage measuring carbon brush and the steam end shaft current measuring carbon brush is good.

[0016] (III) Beneficial effects

[0017] 1. The shaft voltage and shaft current measuring device of the utility model provides a test detection circuit for detecting grounding brush and measuring brush failure, provides a circuit to monitor voltage loop overcurrent and a temperature and humidity controller to adjust the temperature and humidity in the cabinet, has perfect anti-electromagnetic interference capability, and should meet the III level.

[0018] 2. The shaft voltage and shaft current measuring device of the utility model can continuously measure the shaft voltage and shaft current online, and provide a control and setting range. The real-time shaft voltage and shaft current data are reflected in real time through a digital display, and the voltage and current data are collected by the DI / DO signal detection alarm unit to output the alarm and record the alarm information; a test detection circuit is provided for detecting grounding brush and measuring brush failure to prevent poor contact of the carbon brush, a circuit is provided to monitor voltage circuit overcurrent and a temperature and humidity controller is provided to adjust the temperature and humidity in the cabinet, and it has perfect anti-electromagnetic interference capability and should meet the III level. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 It is a circuit diagram of the shaft voltage and shaft current online monitoring device of embodiment 1 of the utility model;

[0020] Figure 2 It is a field wiring diagram of shaft voltage and shaft current of the shaft voltage and shaft current online monitoring device of embodiment 1 of the utility model;

[0021] Figure 3 This is a shaft voltage measurement circuit diagram of the shaft voltage and shaft current online monitoring device of Example 1 of the utility model;

[0022] Figure 4 This is a shaft current measurement circuit diagram of the shaft voltage and shaft current online monitoring device of Example 1 of the utility model;

[0023] Figure 5 This is a circuit diagram of the shaft voltage and shaft current online monitoring device of Example 1 of the utility model when the excitation end brush does not contact the fault;

[0024] Figure 6 This is a circuit diagram of a steam end brush non-contact fault of the shaft voltage and shaft current online monitoring device of Example 1 of the utility model;

[0025] Figure 7 It is a back structural diagram of the shaft voltage and shaft current online monitoring device of Example 2 of the utility model.

[0026] The reference numerals in the figures are:

[0027] 1. DI / DO signal detection alarm module, 2. Voltage axis current measurement device, 3. Current relay, 4. Transmitter. DETAILED DESCRIPTION

[0028] The following is a further detailed description of the specific implementation of the present utility model in conjunction with the accompanying drawings and embodiments. The following examples are used to illustrate the present utility model, but are not intended to limit the scope of the present utility model.

[0029] In the description of the present utility model, unless otherwise specified, "multiple" means two or more than two; the orientation or position relationship indicated by the terms "upper", "lower", "left", "right", "inner", "outer", "front end", "rear end", "head", "tail", etc. is based on the orientation or position relationship shown in the drawings, which is only for the convenience of describing the present utility model and simplifying the description, and does not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation of the present utility model. In addition, the terms "first", "second", "third", etc. are only used for descriptive purposes and cannot be understood as indicating or implying relative importance. In the description of the present utility model, it should be noted that, unless otherwise clearly specified and limited, the terms "connected" and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection, a direct connection, or an indirect connection through an intermediate medium. For ordinary technicians in this field, the specific meanings of the above terms in the present utility model can be understood according to specific circumstances.

[0030] Example 1

[0031] The technical solution adopted by the utility model is as follows:

[0032] like Figure 1 , Figure 2 , Figure 3 , Figure 4 , Figure 5 ,and Figure 6 As shown, the utility model discloses an online monitoring device for shaft voltage and shaft current, comprising: a junction box, a brush monitoring module, a shaft voltage and shaft current measuring device, a through-type current transformer, a current relay, an excitation end shaft voltage measuring carbon brush and a steam end shaft current measuring carbon brush; the shaft voltage and shaft current measuring device is electrically connected to the brush monitoring module; the through-type current transformer is connected to the shaft voltage and shaft current measuring device through a connection point of a secondary high end of a transformer output line and a connection point of a secondary high end of a transformer output line; the excitation end shaft voltage measuring carbon brush is electrically connected to the junction box; the steam end shaft current measuring carbon brush is electrically connected to the through-type current transformer.

[0033] It should be noted that the shaft voltage in this embodiment is measured at the steam end (TE) and the excitation end (EE) of the shaft. The grounding carbon brush must be at the steam end (TE) to ensure that the shaft can be reliably grounded. Continuous shaft voltage measurement is achieved by measuring the carbon brush at the excitation end (EE), and the transmitter allows high resistance to ground potential measurement. The fuse must be installed in the measurement circuit. The shaft current is measured by a current transformer (nano gold, with an accuracy of not less than 0.5 levels in the frequency range of 50 to 1000 Hz) installed on the line between the grounding brush at the steam end (TE) and the grounding point. The grounding potential for voltage and current measurement must be consistent and uniformly connected to the turbine grounding point.

[0034] The grounding plate is connected to the junction box through a wiring line, and the lead-out wire of the through-type current transformer is connected to the grounding plate. The brush monitoring module includes a DI / DO signal detection alarm module, a display module and a TCS / DCS system. The shaft voltage and shaft current measuring device transmits signals to the DI / DO signal detection alarm module, the display module and the TCS / DCS system through a transmitter. The display module includes a shaft voltage display meter and a shaft current display meter. Because the shaft grounding method and the contact resistance of the carbon brush determine the size of the shaft current, this shaft current can be released to the ground at other positions on the turbine shaft side, so it is necessary to monitor the reliable quality of the generator steam end (TE) shaft grounding. The DI / DO signal detection alarm unit collects voltage and current data to alarm output and record alarm information; provides a test detection circuit for detecting grounding brushes and measuring brush failures to prevent poor contact of carbon brushes. The temperature and humidity controller provides a circuit to monitor voltage circuit overcurrent and the temperature and humidity controller adjusts the temperature and humidity in the cabinet, and has perfect anti-electromagnetic interference capabilities.

[0035] The measured shaft voltage and shaft current are sent to the DI / DO signal detection alarm module, display unit (shaft voltage display instrument and shaft current display instrument) and TCS / DCS system through the transmitter 4~20mA signal.

[0036] The complete set of the utility model is composed of a cabinet: the cabinet is equipped with current transmitter, voltage transmitter, DI / DO signal detection alarm unit, shaft voltage and current digital display meter, industrial computer, display, current transformer, test circuit, overcurrent protection circuit, temperature and humidity controller, alarm lamp and button and other components.

[0037] The shaft voltage signal range of the product of this embodiment is: 0-30V; shaft current signal range: 0-10A; shaft voltage signal input impedance: >20kΩ; system accuracy: ±1.0%. Output: 2-way 4-20mA output (transmitter), 6-way alarm output (signal detection alarm unit).

[0038] Example 2

[0039] like Figure 7As shown, the difference between this embodiment 2 and embodiment 1 is that the shaft voltage and shaft current online monitoring device also includes a cabinet; the DI / DO signal detection alarm module 1 and the voltage shaft current measuring device 2 are both installed on the cabinet. The shaft voltage and shaft current measuring device is installed on the upper part of the DI / DO signal detection alarm module. The transmitter is installed on the upper part of the voltage shaft current measuring device. The current relay 3 and the transmitter 4 are arranged in parallel. The shaft voltage and shaft current online monitoring device also includes a manual test button, which detects whether the grounding of the excitation end shaft voltage measuring carbon brush and the steam end shaft current measuring carbon brush is good. This embodiment provides a manual test button, which can detect whether the carbon brush is well grounded at any time. At this time, the generator must be connected to the power grid and run for at least more than 15 minutes for the detection test to be effective.

[0040] When this embodiment is implemented, the excitation end brush does not contact the shaft, and the measured shaft voltage is zero. The shaft current still flows through the fault-free steam end grounding brush, and the current that originally flows through the internal resistance Ri of the voltage transmitter at the excitation end changes to flow through the high-resistance insulation resistance. When the shaft current decreases to zero, it means that the shaft current no longer flows through the closed loop. Since the steam end is not grounded, the charge from the turbine side may increase the shaft voltage.

[0041] The above description is only a preferred embodiment of the utility model, and does not limit the patent protection scope of the utility model. Any equivalent structural transformation made using the contents of the utility model specification and drawings, directly or indirectly used in other related technical fields, is also included in the protection scope of the utility model.

Claims

1. A shaft voltage and shaft current online monitoring device, characterized in that: include: a junction box; A brush monitoring module; A shaft voltage and shaft current measuring device; the shaft voltage and shaft current measuring device is electrically connected to the brush monitoring module; A through-type current transformer; the through-type current transformer is connected to the shaft voltage and shaft current measuring device through the connection point of the secondary high end of the transformer output line and the connection point of the secondary high end of the transformer output line; An excitation end shaft voltage measuring carbon brush, wherein the excitation end shaft voltage measuring carbon brush is electrically connected to a junction box; A carbon brush for measuring shaft current at the FAW end; the carbon brush for measuring shaft current at the FAW end is electrically connected to a through-type current transformer.

2. The shaft voltage and shaft current online monitoring device according to claim 1, characterized in that: It also includes a grounding plate, which is connected to the junction box through wiring, and the through-type current transformer leads out a wire connected to the grounding plate.

3. The shaft voltage and shaft current online monitoring device according to claim 1 or 2, characterized in that: The brush monitoring module includes a DI / DO signal detection alarm module, a display module and a TCS / DCS system.

4. The shaft voltage and shaft current online monitoring device according to claim 3, characterized in that: The shaft voltage and shaft current measuring device transmits signals to the DI / DO signal detection alarm module, the display module and the TCS / DCS system through a transmitter.

5. The shaft voltage and shaft current online monitoring device according to claim 4, characterized in that: The display module includes a shaft voltage display instrument and a shaft current display instrument.

6. The shaft voltage and shaft current online monitoring device according to claim 5, characterized in that: It also includes a cabinet; a DI / DO signal detection alarm module and a shaft voltage and shaft current measuring device are both installed on the cabinet.

7. The shaft voltage and shaft current online monitoring device according to claim 6, characterized in that: The shaft voltage and shaft current measuring device is installed on the upper part of the DI / DO signal detection and alarm module.

8. The shaft voltage and shaft current online monitoring device according to claim 7, characterized in that: The transmitter is installed on the upper part of the voltage axis current measuring device.

9. The shaft voltage and shaft current online monitoring device according to claim 8, characterized in that: It also includes a current relay, which is arranged in parallel with the transmitter.

10. The shaft voltage and shaft current online monitoring device according to claim 1 or 2, characterized in that: It also includes a manual test button, which detects whether the grounding of the excitation end shaft voltage measuring carbon brush and the steam end shaft current measuring carbon brush is good.

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