RU2100818C1 - Device for contactless measurement of space in synchronous electric machine - Google Patents

Abstract

FIELD: electric engineering, instruments. SUBSTANCE: device has light source, photodetector, units which measure displacement and its value. In addition device has units which provide selection of measurement moments with respect to rotation of electric machine rotor. EFFECT: increased functional capabilities. 1 dwg

Description

 The invention relates to electrical engineering, in particular to the control of the air gap of a synchronous electric machine, for example a hydrogenerator.

 A device is known for monitoring changes in the air gap of a synchronous electric machine, comprising a measuring induction sensor installed in the air gap and connected to an electronic circuit.

 The existing device for measuring the air gap in the generator is based on the analysis of the EMF of the magnetic field induction in the gap, however, the irregularity of the magnetic flux, i.e. the difference in the magnitude of the magnetic flux under the various poles of the rotor is due not only to the size of the air gap under each pole, but also to the structural differences of the poles and the presence of windings in the pole winding. In addition, the magnitude of the magnetic flux under each pole is smoothed by the influence of neighboring poles. Finally, the principle of operation of this device does not allow you to control the change in the air gap when removing the excitation and stopping the generator.

 The above reasons do not allow to accurately estimate the amount of air gap under each pole of the rotor and the change in the air gap of the generator when removing the excitation and stopping the generator.

 Closest to the invention in technical essence is a device for non-contact measurement of distances to the object (application N 61-436442, G 01 B 11/14, Japan).

 The device contains two light sources, the line connecting them parallel to the surface of the measured object located at an equal distance from the sources, while the light beams intersect with the surface of the measured object and with each other; two photodetectors that are installed between the sources receive the light reflected by the surface of the measured object and convert it into electrical signals, an offset unit that processes the electrical signals and detects the deviation of the distance between the light sources and the surface of the measured object from the preset value, and based on the result approximates or removes together the light sources and photodetectors from the surface, the unit for determining the position of the bias unit.

 Using this device, you can measure the distance to the object only if this distance remains constant throughout the entire measurement time. For the prototype, this time is due to the response time of the mechanical transmission of the displacement unit, therefore this device is not applicable for measuring distances to rapidly changing objects, as in the case of poles of a rotating rotor.

 The purpose of the invention is the expansion of the scope of the device by storing the amplitude of the pulse with a given serial number in a periodically repeating series of pulses.

 The goal is achieved in that the device for non-contact measurement of the distance to the object, containing a light source and a photodetector, an offset unit and a unit for determining the position of the offset unit, is equipped with a speed indicator, a unit for setting and selecting a pole number, and a sample-storage unit.

 The presence of new units (speed indicator, installation unit and selection of the pole number, sampling-storage unit allows) to expand the scope of the device, i.e. makes it possible to use it for measuring distances to periodically repeating, rapidly changing objects, for example, the poles of the rotor of an electric machine.

 This is achieved by the fact that the signal from each pole is stored for the duration of the measurement in the sampling-storage unit. The serial number of this pole is pre-set in the installation and selection of the pole number, which is started from the speed indicator.

 The drawing shows a block diagram of a device for controlling the air gap of a synchronous electric machine.

 The device contains a light source 1 and a photodetector 2, which are mounted on the end of the insert 3 and directed to the surface of the poles of the rotor 4, the optical axes 1 and 2 being parallel to each other and perpendicular to the surface 4. The other end of the insert 3 is mechanically coupled to the displacement unit 5, which connected to the position determination unit of the displacement unit 6.

 The photodetector 2 is loaded on a buffer cascade 7 located in close proximity to it, which is connected to the sampling and storage unit 8 and to the installation and selection unit of the pole 9. The installation and selection of the pole number is connected to the speed indicator of the turbine shaft 10 and the sampling unit - storage 8. Block sampling storage 8 is connected to the offset unit 5.

 The device operates as follows.

 When the rotor of the hydrogenerator rotates, the light from the source 1 falls on periodically repeating surfaces, is reflected from them and enters the photodetector 2. The luminous flux incident on the photodetector turns out to be the modulated value of the changing air gap due to the shape of the rotor. The luminous flux is converted into an electrical signal by a photodetector 2 loaded onto a buffer stage 7, which then goes to the installation and selection of the pole number with a predetermined pole number and to the input of the selection-storage unit 8. The installation and selection of the pole number 9 starts from the speed indicator 10 and is synchronized by pulses from the output of the buffer stage 7. At the output of this block, a signal is generated that allows recording in the sample-storage unit 8. This signal appears every time when passing by the receiver Luce to set, using the installation unit, and select a number pole number. The maximum value of the signal amplitude is stored by the sampling and storage unit 8 and fed to the bias unit 5, where it is compared with the set voltage corresponding to the previously set gap, depending on whether this signal is lower or more than the set voltage, mixing unit 5 brings closer or deletes insert 3 from the studied pole. After the signal coincides with the set voltage, the position determining unit of the bias unit indicates the amount of clearance to the selected pole. After that, the unit for setting and selecting the pole number 9 is set to the next pole number, etc.

 Experimental studies of the proposed device for monitoring the air gap of the hydrogenerator showed that, compared with devices of a similar purpose, the inventive device provides a more informative definition of the air gap as it measures it in various modes of operation of the generator.

Claims (1)

 A device for non-contact measurement of the air gap of a synchronous electric machine, comprising a light source, a bias unit, a photodetector connected to the electrical part of the bias unit, the mechanical part of the bias unit coupled to a light source, a photodetector and a unit for determining the position of the bias unit, characterized in that it is provided a speed indicator, a unit for installing and selecting a pole number, and a sample-storage unit, the output of the photodetector through a current amplifier connected to the inputs of the sample-XP unit neniya and selection unit and setting the pole number, which is connected with timer speed and a sample and hold unit, the output of the sample storage unit is connected to the bias unit.