EA003628B1 - Power converter with rotating/stationary communication/processing means - Google Patents

Abstract

1. A power converter with a rotating electric main machine (1), which main machine has a rotor shaft (3), a rotor winding (7), and an alternating current stator winding (5) for coupling to a power network, a converter (4) rotating with the shaft, a first control equipment (12) rotating with the shaft, an alternating voltage source (2), a stationary second control equipment (13), and a digital wireless communication link (14,15,16,17) between the first and the second control equipment, characterized in that the rotor winding of the main machine is an alternating current winding, that the alternating voltage source is a regulating machine (2) with a rotor rotating with the shaft of the main machine and with a rotor winding (8) that is a multiphase alternating current winding, that the converter is an ac-to-ac converter (4) coupled between the rotor windings of the regulating machine and of the main machine, and that the first control equipment comprises a programmable first digital processor (12) programmed with software to, via control of amplitude and frequency of the voltage supplied to the rotor winding of the main machine, control the power converter (4) in dependence on reference values supplied from the second control equipment via the communication link. 2. A power converter as claimed in claim 1, characterized in that said first digital processor is programmed with software to control the converter to -during normal operation operate as an ac-to-ac converter, -during start-up operate as one of an alternating current multiphase coupler, an alternating current phaseangle/voltage controller, and an alternating current short-circuit coupler, and -during controlled breaking and stopping operate as one of an alternating current multiphase coupler, an alternating current phase-angle/voltage controller, and an alternating current short-circuit coupler. 3. A power converter as claimed in any of the preceding claims, characterized in that said first digital processor is programmed with software to temporarily and autonomously control the power converter in case of repeated and severe disturbances in the digital wireless communication. 4. A power converter as claimed in any of the preceding claims, characterized in that said second control equipment comprises a programmable second digital processor (13) programmed with software to generate said reference values in dependence on measured values of quantities associated with the power converter, and to communicate with super-ordinated control systems. 5. A method for power conversion with a power converter as claimed in claim 1, characterized in that reference values for the power conversion are supplied to the first control equipment from the second control equipment via the communication link, and that the first digital processor is programmed with software to control the power converter by controlling the amplitude and frequency of the voltage supplied to the rotor winding of the main machine in dependence on said reference values.

Description

The present invention relates to a method for converting energy from mechanical to electrical and electrical to mechanical, and to devices for carrying out this method. Energy conversion is performed using a power converter, which contains at least one rotating electrical machine with a mechanical shaft and

- at least one digital processor that rotates with a shaft and which, together with at least one fixed digital processor, performs control, etc.

at least one static converter rotating together with a heap, and

- at least one digital wireless link between rotating and fixed parts.

The power converter is designed to be connected to the external power supply network, or it can operate as the only electric generator that supplies the power supply network. When the power converter is connected to the external power supply network, it can generate a frequency that is synchronous with the existing power supply network, with varying speeds of rotation of the electric machine. When the power converter is the only source of energy for the power supply network, it can generate a constant synchronous grid frequency with varying speeds.

The level of technology

Usually AC machines

- can be designed to operate at a constant or variable speed and

- can work in the mode of the generator and / or engine.

For these two variants of machines, specific specific forms of their execution are known. AC machines, which are essentially designed to operate as a generator, can, however, for example during start-up, operate as an engine. Also, AC machines that are designed to work as a motor can, for a short time, for example during a stop / deceleration process, operate as a generator. It is also known that AC machines can be designed to operate in the mode of both the generator and the engine, for example, to work in the generator mode during the day and to work in the engine mode of a pumped storage hydroelectric station during the night.

AC machines that are designed to rotate at a constant speed are designed as so-called synchronous machines in which the rotor is magnetized by direct current. This means that the magnetic flux in the machine is fixed relative to the rotor. This causes the rotor to rotate with the so-called synchronous speed, which is determined by the number of poles of the stator winding and the frequency of the current of the stator winding. The relationship between the rotor speed of an alternating current machine and the voltage frequency is described in detail in Swedish patent application 8E 9901553-9 A machine with a constant frequency ... This application also describes how you can achieve a constant frequency of the electrical network with varying speed of an electric machine.

Synchronous machines dominate among the AC machines that are used in hydroelectric and thermal power plants. This is due to a number of reasons, among which is the high efficiency of a synchronous machine, its ability to work in an independent mode, i.e. work in power grids without other synchronous machines, as well as the strength of the rotor design and its low cost.

The main electrical voltage required for AC machines in engine mode and the auxiliary electric power required for AC machines in generator mode are now increasingly being supplied by converters. Digital computers are now commonly used to control AC machines and associated converters. Converters are usually installed permanently and are connected between the AC machine and the power network, i.e. the converter is essentially fixed. The same applies to computers that provide feedback control and regulation.

Converters, rotating together with the shaft and made in the form of AC-to-DC converters, are already on the market in the form of brushless exciters for the excitation windings of the AC rotor. One example of such a pathogen is described in the technical prospectus of the company ABB Vgi5111c55 exsieg (Brushless causative agent) 8ΕΟΕΝ / ΗΜ 8-001. This technical brochure shows that the converter, rotating with the shaft, is essentially or basically made on diodes, and the excitation current is controlled by the exciter, rotating with the shaft, through the stator current of the exciter. One of the drawbacks of a brushless driver, such as the one described with a converter built on diodes, is the slow dynamics of the magnetization system. When the so-called power system stabilizer is used, it is assumed that the magnetization system has a relatively short reaction time. This is achieved if the AC-to-DC converter is designed as a thyristor converter. Such a converter is used in the equipment described in the patent.

USA No. 3,671,850 Electric Generator Control System with Radio Feedback Circuit. To control the triggering pulses of a rotating thyristor converter, radio communication is used, and the control system relies on analogue technology. There are no dynamics or measurements of parameters that are included in the control, for example, the temperature-dependent resistance of the rotor winding, etc.

Swedish patent application No. 9901553-9 describes an electric machine formed by an alternating current machine, which in its basic design contains a main machine and a regulating machine with a common mechanical shaft on which the converter is located to rotate with the shaft. The main machine has AC windings on the stator and on the rotor. The main task of the regulating machine is to provide for the rotor winding of the main machine the power / frequency control in the range of interest, in terms of rotational speed, frequency and voltage of the electric machine. The control machine can also be used to perform a variety of side functions, such as, for example, starting the engine for the main machine and rejecting the starting loss of the main machine to an external resistor. A converter rotating with a shaft also has several functions, which are described in more detail in the above-mentioned Swedish patent application. In general, its main task is to function during operation as an AC-to-AC converter. During the start-up cycle, it must be able to function either as a multi-phase AC switching device, or as an AC phase angle / voltage regulator, or as an AC short-circuit device for winding the rotor of the regulating machine. During controlled braking and / or stopping, the converter should function as a phase angle / ac voltage regulator or as a multi-phase AC switching device. However, the data transfer to the rotor and from the rotor in the above-mentioned Swedish patent application is not described.

In the application XVO 97/45919 described a special embodiment of a rotating electrical machine. The high-voltage stator winding is made using cable technology. This means that a transformer is not required to connect to a high-voltage power supply network. Machines designed with this type of stator winding are characterized in that they have a very low current density in the stator conductors, and in that the cooling is performed in the stator plate core at substantially the ground potential.

With an appropriate choice of area and / or protective device of the rotor windings, the machine has a good ability to temporarily, for tens of minutes and sometimes up to several hours, generate a very large reactive power and rotor current. In this regard, in νθ 98/34312 described one of the embodiments of the protective device. In this safety device, the rotor temperature is reproduced in a safety relay located in a power plant. Data transfer to and from the rotor, however, is not described.

In the application PCT / EP 98/007744 concerning the control of the flow of energy in the transmission line, describes a special variant of the magnetization of a direct current of an electric machine, rotating at a constant speed. The stator windings of the electric machine here are connected in series with the conductors of the transmission line without a common neutral point. The rotor of an electric machine is equipped with two / three rotor windings, which are powered by direct current and are offset relative to each other by 90/120 °, to control the amplitude and phase of the voltage of the electric machine. The power supply of the rotor winding is performed through a magnetizing exciter rotating with the shaft and an AC / DC converter / converter for each of the rotor windings. The same application also describes more advanced energy flow control using a second electric machine connected to the same shaft as the first electric machine and connected in parallel with a transmission line, the second electric machine having an AC / DC converter rotating with the shaft. Data transfer to and from the rotor, however, is not described.

For the past several decades, there has been an obvious tendency to miniaturize electronic signal processing circuits. It can be said that telecommunications are now almost completely digital in all their main parts. The signal processing circuits in converter control circuits have become miniaturized due to the fact that there are chips with internal digital signal processing specially designed for converters, both for AC-DC converters and AC-AC converters. Designing such circuits using analog technology does not provide additional advantages, since the resolution of digital circuits, both in amplitude and time, is quite high, and the possibility of installing and adjusting parameters of control circuits at a distance, for example via a digital communication line, is much better .

Drives of electrical machines with converters rotating with a shaft have one problem, namely, a significant need to perform a number of more or less complex operations, such as calculations, decision making, data storage, control, etc. According to the invention, these problems are overcome with the help of a computer rotating with a shaft, where all signal processing takes place numerically. In addition, there is the problem of communication between a computer that rotates with the shaft and a fixed computer with high accuracy and reliability when transferring data in both directions. According to the invention, this communication is carried out by using a new technology, the so-called telemetry, which until now has been used for wireless communication between essentially fixed units.

Data transmission of various kinds for a long time was carried out by means of communication by wire. Telemetry is a field of science and technology associated with automatic wireless data transfer between two terminals. Telemetric technology began to be used 20-30 years ago. In the review article TE. B1a1osk c1 a1. ’Thumbeshigh SOSHGO1 BOOH1ETH, νοί. 51, N0.6, Shpe 1978, pp.45 - 48, Tetemen1u - al eahu uau 1o sbesk oi! Go! AbddasYpegu (Telemetry - an easy way to control rotating machines) was summarized technology of the time. In the abstract B.T.S’bo \ y. S.N. S’be \ y. Sophegeps Progos. ΤΕΝί.ΌΝ 84, up 1pS SopG. op Sphiteg & 1pbih1n1 E1esboshsh & ArrbsRoph. 1ЕЕЕ, № \ у Уагк, ΝΥ, IBA, 1984, рр.3-5 Kabyu Geteteggu huhGhet Gog u | Lebop teahigetepG oGo1a11dd tasbtegu (Radiotelemetric system for measuring vibration of rotating machines) is described as from the speed of rotation. The signals from the strain gauges on the turbine blades are amplified, modulated and sent from rotating parts to fixed instruments for measuring and analyzing using frequency modulation.

As for electrical machines, contactless measurement systems were used to transmit temperature signals from the moving parts of transformers in the power supply of German railways 25 years ago, according to an article by W. Raahsb. Ό. Bsbet. A sabohrehhhhhhhg 1974, 22 pp.

The article A. O \ uhh. R. HUPNash. Tubeteahighetosh og hbat opa 1attaGeb b1khs G1u \ ubee1 (Measurement of deformation of a lamellar disk of a flywheel), 1p (erp (1аpa1 Roeg Sepegabop, νο1.6, No. 6. Tb-Aid. 1983, pp. 24-27, described as Computers are used to transfer information from rotating strain gauges on flywheels.

In order to allow wireless communication within up to 100 meters between personal computers and between mobile phones and their associated peripherals, wireless communication has been developed at a high rate over the past few decades. Currently, there are licensed frequency bands, for example, 433 MHz and 2.45 GHz, the so-called industrial-scientific-medical (1BM) bands, which are used for communication over short distances in an environment with electromagnetic interference. The Institute of Electrical and Electronics Engineers (1EEE) is currently working on a communication standard also at 5 GHz (1EEE 802.11).

Article 1. NaagGhep V1pe1oo1b - Not shpsegkha1 gabu 1ShegGase Gog ab bos, \ ubotehh soppesbsbu (VSHeGoGb - universal radio interface designed for wireless communication), Epskhhop-Vse1e \ y. νο1.75, Ho.3, 1998, pp. 110-117, describes a recently commercially available digital communications technology. Its typical data is a transmission rate of 1 Mbit / s and the ability to communicate over short (<100 m) distances between different fixed devices, as well as a connection to the local network (LAX). These communication lines, the so-called asynchronous communication lines (ASB), allow symmetrical and / or asymmetric data transmission between the master device and the seven slave devices. Data can be transmitted at slightly different rates, depending on the choice and method of packing and protection of the transmitted data.

Since the emission of interference from converters in the gigahertz range is very small, and the communication lines according to the existing de facto HiGoGB standard or 1EEE 802 standard are largely immune to electromagnetic interference, wireless communication can be provided between rotating and fixed parts of the converter up to 721 kbps /with.

There are few examples of implementation and descriptions of problems related to how to perform measurements in a digital way on rotating parts, where computers are used for data analysis and transmission. One example of this, in connection with measurements of the mechanical and electrical parameters of rotors in hydroelectric generators, is described in the article by GP. Ebshopbes, T.S. 1ЕЕЕ Тесбшса1 Аррбсабопх Собгегепсе, № Рбсоп / 96. Sop003628

Gegepse Kesogb (Ca1. Νο. 96CH35928),, Νο \ ν Ourk, ΝΥ, IZA; ρρ. 73-77). The article shows how a scanner mounted on the rotor of a hydroelectric generator uses a sensor system to measure the critical operating parameters of the stator. Radiated heat energy, air gap between the stator and rotor, radio frequency radiation and magnetic flux are measured. The combined information from the entire generator allows for a continuous assessment of the state of the generator, as well as long-term analysis for maintenance planning. In addition, the article states that for successful measurement of body parameters rotating at high speed and for transmitting data to the central computer in order to provide valuable information to the user, coordination of many parts of the system, such as a device for mounting sensors and powering electronics, is required. located on the rotor, telemetry for two-way communication, a computer control unit, as well as software for control, data conversion, a video monitor for analysis and a video monitor ELSE. In addition, maintenance systems must operate satisfactorily in demanding conditions, which include high centrifugal forces, large temperature changes, mechanical vibration, oppositely directed electric and magnetic fields, and relatively high sensor speeds relative to the measured objects.

The invention and its advantages

As stated in the introductory part of the description, the invention relates to a power converter in the form of an electric machine with a mechanical shaft and at least one digital processor that rotates with the shaft and which, together with at least one fixed digital processor, controls using digital control , at least one converter rotating together with the shaft, with at least one digital communication link between the rotating and fixed parts.

The digital processor contains a computer that, in addition to the internal control and memory functions, is equipped with data processing programs for the corresponding operation mode.

A digital communication line contains a transceiver rotating with a shaft for receiving / transmitting digital data, associated with a processor rotating with a shaft, an antenna that rotates with the shaft, and a fixed antenna for digital wireless transmission, as well as a fixed transceiver connected to a fixed processor , to receive / transmit the above digital data.

Using a power converter made according to the invention, the parameters associated with this converter, such as torque, speed, active power, reactive power, etc., can be controlled in a brushless manner. It is also possible, in comparison with the prior art, to improve the stability of the electrical power systems to which the power converter is connected. Further advantages of the invention are the ability to provide a controlled start, work, stop and braking of an electric machine, as well as the implementation of adjustment when the machine is put into operation.

In other respects, the power converter according to the invention has the following features:

- wireless data transmission occurs, in a preferred embodiment of the invention, at a radio frequency using digital signals;

- The relevance of the transmitted data is guaranteed by a combination of modeling, assessments, expert systems, compression, filtering and error correction;

- bandwidth requirements for communication can be reduced by transmitting only changes for some of the transmitted signals.

Energy conversion takes place with the participation of the integrated control system, which contains the above-mentioned rotating and stationary digital processors with brushless digital coupling, as well as sensors for measuring and monitoring the relevant parameters. Processors usually operate as a master / slave, with a rotating processor as a slave. The stationary processor essentially manages energy conversion, measures and controls parameters related to the stator of the electric machine, and communicates with other external control systems. The main task of the rotating processor is to control the converter, which rotates with the shaft of the electric machine, and to measure and control parameters associated with the rotor of the machine.

The rotating processor is programmed so that in the case of strong and repetitive interference in wireless digital communication, it can autonomously control, for example, a power converter for a certain period of time.

Commissioning of stations with electric machines, which include converters, traditionally occurs by adjusting / adjusting parameters in control systems when commissioning stations. The invention provides significant advantages in this respect, since this can be done by transmitting data to rotating parts using a wireless link. Updating and adjustment of the set parameters can occur continuously, as the volume of information about the components in the station increases, and with changes in the attached electrical power systems during the life of the station.

As is clear from the above, for electric machines associated with this invention, it is very important to be able to start, adjust and then control and protect the converters rotating with the shaft. More specifically, it is necessary to fix the points in time when the conductors that are included in the converters must start / stop passing current, essentially, to convert mechanical energy into active electrical energy and / or reactive energy, and vice versa.

Description of preferred embodiments of the invention

An embodiment of the invention shown in the drawing. The power converter according to the invention can be used as an electric generator or as an electric motor. In a preferred embodiment of the invention, the power converter comprises a rotating electric machine in the form of a main machine 1 and a regulating machine 2 with a common mechanical shaft 3. In the drawing, the electric machine is shown as an electric machine with a vertical shaft, but it can obviously be implemented as an electric machine horizontal shaft. On the common shaft, rotating with it, is the converter 4, made in the form

- an AC-to-AC converter, which can be implemented as a matrix converter, a cyclo-converter or an AC converter with an intermediate DC link for supplying the rotor windings (8Е 9901553-9) with an alternating current or

- an AC-to-DC converter for supplying a DC current to the rotor windings (windings), for example, with an arbitrary phase position relative to the rotor (PCT / EP 98/007744).

The main machine is made with a stator winding 5, designed for the so-called medium voltage, i.e. up to 30 kV. For connection to the high-voltage network, a transformer 6 is inserted. If the machine is made in accordance with \ νθ 97/4519, the stator winding 5 can be designed for high voltage, in this case there is no transformer 6. The winding 7 of the main machine rotor is shown in the embodiment of the invention as an alternating current winding, which is powered by the difference frequency from the AC-to-AC converter (see 8E 9901553-9), which is necessary to obtain the desired frequency of the machine when it is running as a generator, and get the desired speed of rotation of the rotor of the electric machine when it works as a motor.

The winding 8 of the rotor of the machine feeds the AC-to-AC converter, which rotates with the shaft. The drawing shows that the power is supplied by three-phase voltage. The invention includes powering in a variety of different ways, such as, for example, 2x3-phase voltage, 2-phase voltage, 2x2-phase voltage, or, in general, Ν-phase voltage. The stator winding 9 of the regulating machine in the shown embodiment of the invention is powered by a current from a controlled converter 10 with separate power supply, for example, through an auxiliary transformer 11 connected to an electrical power supply network. The stator winding may also, alternatively, be implemented as an alternating current winding for use when starting an electric machine.

Converter 4, rotating with the shaft, is used in combination with the regulating machine and external devices connected to the regulating machine for starting, stopping and braking, according to 8Е 9901553-9.

As follows from the description of the invention and the claims, the power converter contains a digital processor 12 rotating with an electric machine shaft and a fixed digital processor 13. These two processors are connected to each other via one, two or more redundant wireless digital communication lines. The communication line contains a transceiver 14 rotating with a shaft for receiving / transmitting digital data, connected to a processor 12, rotating with a shaft, an antenna 15 rotating with a shaft, and a fixed antenna 16 for wireless digital data transmission, as well as a fixed transceiver 17 for receiving / transmissions of the aforementioned digital data, attached to the fixed processor 13. The fixed processor appropriately interacts with other fixed devices for general control, protection, etc., as shown by the two her arrow 18.

The purpose of the processors was generally described when describing the essence of the invention. A detailed description of all their functions, such as control, protection, etc., is outside the scope of this invention. However, the accompanying drawing shows a number of measuring devices, for example, devices 19, 20 and 21 for measuring the input / output current of an AC-to-AC converter and main machine current / voltage, respectively, as well as devices 22 and 23 for measuring the temperature of a rotor / stator winding main machine.

The directions of the energy fluxes are also shown in the drawing by means of arrows on the current-carrying conductors. So, for example, the conductor between the stator winding 5 and the transformer 6 of the main machine is marked with a double-headed arrow, indicating that the electric machine is capable of operating both as an electric power generator and as an engine. Similarly, the antenna wire is marked with arrows indicating the direction of transmission of the corresponding signals.

Claims (5)

CLAIM 1. A power converter containing a main rotating electric machine (1), which has a rotor shaft (3), a rotor winding (7) and a stator alternating current winding (5) for connecting to the power supply network, a converter (4) rotating together with the specified the shaft, the first control device (12), rotating with the specified shaft, the source (2) of the alternating voltage, the fixed second control device (13) connected to the first through a digital wireless communication line (14, 15, 16, 17), while the rotor winding of the main machine is about AC coil, AC voltage source is made in the form of a regulating machine (2) with a rotor rotating with the main machine shaft and with the rotor winding (8), which is a multi-phase AC winding, the converter is an AC converter into AC connected between the windings of the rotors of the regulating machine and the main machine, and the first control device contains the first programmable digital processor (12), programmed to control the converter (4), changing the amplitude and the frequency of the voltage applied to the rotor winding of the main machine, depending on the reference values received from the second control device. 2. Power converter according to claim 1, characterized in that the first digital processor is equipped with a program for controlling the converter so that during normal operation it functions as an AC-to-AC converter, during start-up it works or as a multi-phase AC switching device , or as a phase angle / ac voltage regulator, or as a short-circuit AC device, and during controlled braking and stopping, it worked or as a multi-phase comm device tation of alternating current, or as a phase angle / voltage regulator of alternating current, or as a short-circuit device of alternating current. 3. Power converter according to any one of the preceding paragraphs, characterized in that the first digital processor is programmed to temporarily and autonomously control the power converter in case of repeated and significant violations of digital wireless communication. 4. Power converter according to any one of the preceding paragraphs, characterized in that the second control device comprises a second programmable digital processor (13) programmed to generate reference values depending on the measured values of parameters associated with the power converter and interact with control systems higher level. 5. The method of energy conversion using a power converter according to claim 1, characterized in that the reference values for energy conversion are supplied to the first control device from the second control device via a communication line, and the first digital processor is programmed to control the converter (4), by varying the amplitude and frequency of the voltage applied to the rotor winding of the main machine, depending on the obtained reference values.