RU2432461C1 - High-voltage borehole generator - Google Patents

Abstract

FIELD: electricity.

SUBSTANCE: high-voltage borehole generator is equipped with a protective body, an electrical connection, at least with one fixing unit, a rotor with a hydraulic turbine and a device of mechanical power conversion into electric one. The device of mechanical power conversion into electric one is made as a machine generator and a piezogenerator connected by electric wires. At the same time the piezogenerator is arranged as a pack of piezoelectric plates and a device of vibration generation, using a magnetostrictive effect and comprising a winding and a magnetic core, installed inside it and resting with its end against the pack of piezoelectric plates via a flexible membrane. Between the rotor and the device of mechanical power conversion into electric one there is a magnetic coupling, comprising a master and a slave half-couplings. Between the master and the slave half-couplings there is a tight partition, comprising parts of magnetic permeable material. At the same time the master half-coupling is connected to the rotor, and the slave one - to the shaft one. On the upper end of the rotor there is a hole for lubricating liquid filling into the cavity of the master half-coupling.

EFFECT: increased reliability and capacity of generator with reduction of diametrical dimensions and weight of power generator, simplification of its design.

2 cl, 4 dwg

Description

The invention relates to electric machines. Specifically, the invention is intended for a high-voltage generator installed in the well and intended, for example, to perform hydraulic fracturing. The generator converts the energy of the flushing fluid into electrical energy, which is necessary to power the downhole navigation and geophysical instruments during drilling and the transmitter of the electromagnetic communication channel. For the telemetry system to work at great depths, an increase in the power of the transmitting device to 1 kW or more is required. To get more power with small dimensions of the generator is very problematic

A self-contained turbine unit (electric generator) is also intended for supplying electric energy to the telemetry system, containing a hydroturbine driven by a washing fluid stream, an oil-filled stator filled with an epoxy compound, and a rotor of an alternating current generator with permanent magnets located on the same shaft with a hydraulic turbine ( Molchanov A.A., Siraev A.X., Borehole autonomous systems with magnetic recording. - M .: Nedra, 1979, pp. 102-103).

This generator consists of a stator located inside the unit and a six-pole annular magnetic rotor made from the outside. The rotor is also a casing for the working blades of a three-stage hydraulic turbine. In front of each stage of the working blades of the hydraulic turbine, in turn, there are three stages of guide vanes assembled on the outer casing, which increases the diameter of the device. To prevent the flushing fluid from entering the generator and the bearing units, sealing devices are installed, the internal cavity of the generator is filled with transformer oil.

Due to the fact that the generator operates in the temperature range from -40 to + 130 ° C, at drilling depths of up to 3500 m or more, and the oil volume changes with temperature, a compensator for pressure and thermal expansion of the lubricating fluid (oil) is introduced. The compensator for pressure and thermal expansion of the lubricating fluid is made inside the inlet fairing of the generator. It consists of two thin profile plates, one of which is convex and the other is concave. The compensator for pressure and thermal expansion of the lubricating fluid is designed to compensate for changes in the volume of oil in the oil-filled cavity of the generator under operating conditions with increasing temperature, as well as equalizing the pressure inside and outside the generator.

The disadvantages of this generator are: low reliability, low resource, large dimensions and weight of the device, design complexity.

These shortcomings are caused, first of all, by the fact that a multistage turbine with guide vanes is used as a drive. The use of a hydraulic turbine with guide vanes as a drive places high demands on the quality of cleaning the washing liquid from fractions of drill cuttings and foreign objects, the ingress of which into the gap between the working and guide vanes of the hydraulic turbine can cause it to stop (jamming). The presence of guiding devices of a hydraulic turbine increases the diametrical dimension of the electric generator, which is undesirable when drilling wells of relatively small diameter.

The second design flaw is the complexity and unreliability of the pressure compensator and thermal expansion of the lubricating fluid. Due to the elasticity of the walls of the compensator, the pressure of the lubricating fluid is always less than the pressure of the environment. This can result in flushing fluid entering the generator’s lubrication system and in the wear of bearings, seals and other parts.

Known electric generator according to the patent of the Russian Federation No. 2331149, prototype. This generator contains a protective housing, at least one attachment point, a rotor with a turbine and a device for converting mechanical energy into electrical energy.

The disadvantages of the generator unreliability and design complexity due to the low reliability of the field windings, the insufficient power of the generator with its limited diametrical dimensions.

The tasks of its creation are to simplify the design, increase power while reducing the diametrical dimensions and weight of the generator.

The solution of these problems was achieved in a high-voltage downhole generator containing a protective casing, an electrical connector, at least one attachment point, a rotor with a hydraulic turbine and a device for converting mechanical energy into electrical energy, in that according to the invention, the device for converting mechanical energy into electrical energy is made in the form of connected electrical wires of the machine generator and piezoelectric generator. The piezoelectric generator is made in the form of a package of piezoelectric plates and a device for creating vibrations using the magnetostrictive effect and containing a winding and a magnetic circuit installed inside it and abutting with its end face a package of piezoelectric platinum through a flexible menbrane. Between the rotor and the device for converting mechanical energy into electrical energy, a magnetic coupling is installed, containing the leading and driven half-couplings. The magnetic coupling can be made face. The magnetic coupling may be cylindrical. Between the driven and leading coupling halves, a sealed partition may also be made containing parts of magnetically permeable material, while the driving coupling coupling is connected to the rotor, and the driven coupling to the shaft. The inner cavity of the drive clutch is filled with lubricant. At the upper end of the rotor, an opening can be made for filling the lubricating fluid into the cavity of the driving coupling half. The generator may contain at least one compensator for pressure and thermal expansion in communication with the cavity of the leading coupling half.

The invention is illustrated by drawings, where:

figure 1 presents the first variant of the generator,

figure 2 presents a device for compensating for pressure and thermal expansion in the initial position,

figure 3 presents a device for compensating pressure and thermal expansion in the working position,

figure 4 presents the second variant of the generator.

The high-voltage downhole generator (Figs. 1 ... 4) is installed in the drill string or in the casing (not shown) and contains a protective housing 1 and at least one attachment device 2. In the attachment device 2 of the electric generator, holes 3 are made for passage of the drill solution. The high-voltage downhole generator contains a rotor 4 with a hydraulic turbine 5. The hydraulic turbine 5 has obliquely mounted flat blades mounted at an angle of 20 ... 60 °. The protective housing 1 has an electrical connector 6 at the bottom, to which high-voltage wires 7 are connected from a device for converting mechanical energy into electrical 8.

A device for converting mechanical energy into electrical energy 8 comprises a machine generator 9 and a piezoelectric generator 10 connected by wires 11.

The machine generator 9 includes a rotor of the generator 12 with permanent magnets 13 and an excitation winding 14 mounted inside the protective housing 1. The rotor of the generator 12 is mounted on bearings 15 and 16, which are protected by seals 17 and 18. The machine generator has an internal cavity 19, which cannot be sealed for the presence of the rotor 4.

To fill the cavity 19 with a lubricating fluid, an axial hole 20 is provided, made in the rotor 4 and plugged with a screw 21.

To compensate for the flow of lubricating fluid, thermal expansions and variable pressure in the well, at least one compensator for pressure and thermal expansion 22 (FIGS. 2 and 3) is provided, made in front of the protective housing 1 of the generator (FIG. 2). It is most expedient to perform 2 ... 8 pressure compensators and thermal expansion 22 and place them inside the protective housing 1 from the side of the turbine 5, since only the cavity 19 needs compensation, and the other cavities are sealed and can be filled with an inert gas and do not need compensation when provided that the walls of the protective housing are of sufficient thickness.

Each compensator for pressure and thermal expansion 22 contains a compensation piston 23 mounted and sealed relative to the protective housing 1. The cavity 24 under the compensation piston 23 has a hole (s) 25 connected to the cavity 19, and the cavity 26 above the compensation piston 23 is connected with a hole (s) 27 with environment to compensate for pressure changes and thermal expansion of the lubricant. Compensation piston 23 is spring-loaded by spring 28 towards the leading coupling half 37 to create excess pressure in the cavity 19.

In the protective housing 1 in the sealed cavity 29 is installed a piezoelectric generator 10, which contains a package of piezoelectric plates 30 installed between the flexible membrane 31 and the insulating gasket 32. and also a vibration generating device 33. The vibration generating device 33 includes a winding 34 and a magnetic circuit 35 that is in contact with flexible membrane 31.

A possible embodiment of a high-voltage downhole generator with a magnetic coupling 36 (figure 4). The magnetic coupling 36 includes a leading and a driven half-coupling 37 and 38 by permanent magnets 39 of an airtight baffle 40 between them having magnetically permeable parts 41. Two versions of the magnetic coupling 36 are possible with a mechanical coupling or a cylindrical coupling. The cavity 42 of the driving coupling half 37 is isolated from the cavity 19 of the machine generator 9 by a partition 43 in which the bearing 44 and the seal 45 are installed. In the protective housing 1, a drainage hole 46 is made in its upper part, closed by a threaded plug 47. The drainage hole 46 is designed to discharge air when filling the cavity 42 with a lubricating fluid.

During the operation of the generator (Fig. 1), the drilling fluid passes through a hydraulic turbine 5, which begins to rotate with the rotor 4. The rotor 4 drives the rotor of the generator 12 with permanent magnets 13. The magnetic flux crosses the field windings 14 and an electric current arises in them, which wires 11 enters the winding 33. The magnetic flux created in the winding 33 acts on the magnetic circuit 35. Based on the magnetostrictive effect, the length of the magnetic circuit 35 changes with the frequency of the current in the winding 33. Vibration acts through a flexible brane 31 to the package 30 of the piezoelectric plate in which a high voltage is generated. High voltage through high-voltage wires 7 is transmitted to the electrical connector 6.

When changing the volume of the lubricating fluid in the cavity 19 (Fig. 1) or 42 (Fig. 2) for any reason, the compensation piston 23 is moved accordingly. As a result, a pressure of 2 ... 4 atm is always maintained inside the cavity 19 (or 42) than environmental pressure. This prevents the penetration of abrasive particles contained in the drilling fluid into the cavity 19. If several pressure compensators and thermal expansion 22 are used, then when one of the holes 25 is clogged (or several holes 25, if 4 ... 8 pressure compensators and thermal expansion 22 are used), the remaining pressure compensators and thermal expansion 22 will perform their function, even when one of them. This significantly increases the reliability of the generator and its resource.

The application of the invention allowed:

1. To simplify the design of the generator due to the rejection of the use of field windings and permanent magnets.

2. Increase the power and voltage at the electrical terminals of the generator through the use of an electrostatic generator capable of creating high voltage.

3. Significantly increase the service life of the bearing by reducing the diameter of the rotor to the minimum possible.

4. To reduce the imbalance of the rotor of the generator by reducing its diameter and length. Only a hydraulic turbine and a driven coupling half (in the second embodiment of the generator) are fixed on the rotor.

5. Improve the reliability of the generator by fully sealing its main cavities: the cavity of the driven coupling half and the electrostatic generator and by sealing the cavity of the driving coupling half with respect to the relatively small diameter of the rotor.

6. Improve maintainability of the generator.

Claims (2)

1. A high-voltage downhole generator containing a protective housing, an electrical connector, at least one attachment point, a rotor with a hydraulic turbine and a device for converting mechanical energy into electrical energy, characterized in that the device for converting mechanical energy into electrical energy is made in the form of a machine generator connected by electric wires and a piezoelectric generator, while the piezoelectric generator is made in the form of a package of piezoelectric plates and a device for creating vibrations using magnetostrictive an effect containing a winding and a magnetic circuit installed inside it and abutting its end against a packet of piezoelectric plates through a flexible membrane, a magnetic coupling is installed between the rotor and the device for converting mechanical energy to electrical energy, containing the leading and the driven half-couplings, a sealed partition is made between the driven and leading half-couplings, containing parts of magnetically permeable material, while the leading coupling half is connected to the rotor, and the driven coupling to the shaft, holes are made on the upper end of the rotor e for filling lubricating fluid into the cavity of the drive coupling half. 2. The generator according to claim 1, characterized in that it contains at least one compensator for pressure and thermal expansion, communicating with the cavity of the leading coupling half.

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