SE514818C2 - Constant frequency machine with varying / variable speed and procedure for such machine - Google Patents

Abstract

A constant-frequency machine with a varying/variable speed which comprises a main machine (1) and a regulating machine with a com on shaft (2) and a converter (28, 51) which rotates with the shaft and is connected between the rotor windings (3, 29) of the main machine and the regulating machine, and wherein the converter, during operation, is arranged as an ac-to-ac converter, and wherein, during starting, it is arranged as an ac polyphase coupler or as an ac phase-angle/voltage regulator or as an ac short-circuit coupler, and wherein, during controlled braking and stopping, it is arranged as an ac polyphase coupler, or as an ac phase-angle/voltage regulator, or as an ac short-circuit coupler.

Description

35 40 3 - 300 MW. Motor drives up to 100 MW and higher can be manufactured.

Machine effects both below and above the mentioned power ranges can be used to advantage.

The machine can be used in connection with hydropower machines, pumped storage power plants, wind turbines, gas and steam turbines as well as as a phase compensator, power fate regulator and transmission link in power grid contexts, and as a power source for various motor drives.

The reported embodiments of the invention and the description of the state of the art show so-called radial fate machines. The machine can also be fully or partially made with one or more of your axial fate machines.

When it comes to machines for generating electrical power, there are a number of accepted concepts such as electricity generator, electric power generator, hydropower generator, hydrogen generator etc. In this patent specification, these “generators” will be referred to as “electric generators” unless a more detailed specification is necessary for the purpose.

STATE OF THE ART, THE PROBLEMS In general, it applies to AC machines that they can be used for both generator operation and motor operation, but that the optimal embodiments differ somewhat. There is thus a "state of the art" which is specific to the two operating cases. i During generator operation, the task of the machine is to generate electrical power. To be able to do this, the electricity generator is driven by a drive device whereby mechanical power is converted into electrical power. Since the generation of electrical power is generally associated with power grids, special requirements are placed on the constant maintenance of both voltage and frequency, as well as on the control and regulation of both active and reactive power. The following description of the state of the art, with respect to generator operation, will consequently largely be about how to proceed to achieve the desired performance regarding these parameters.

When an AC machine is used in a motor operation, electrical power is converted to mechanical power where the conversion in growing proportion is associated with speed control of the output shaft, ie of the machine's speed. This applies .- \ 20 25 30 .___. -_,. . '. e ._,. .r ... _ - .- _ ._ <.. _. .

L- ... i. f.

N-s sNÅ .. n. U .... l. _. . . . . . -. a _. f. .. H especially when applying headlined inventions. The description of the prior art below with respect to motor drives will consequently mainly be about speed-controlled motor drives. Mainly motor drives refer to regulation of torque and speed of the output shaft.

However, in the same way as generation, engine operation is also associated with control and regulation of both active and reactive power.

A significant problem area when it comes to motor drives with AC machines is their start, ie running from zero speed to the current control range around synchronous speed. The description of the state of the art will also include a description of existing starting methodologies in order to be able to demonstrate the improved starting methods available with alternating current machines according to the invention.

As discussed under "TECHNICAL FIELD", the invention will include a converter. The description of the state of the art both in terms of generator operation and motor operation will therefore mainly refer to embodiments where stream directers are included. From an electrical point of view, current converters are described by means of established basic symbols according to Figure 1 which unambiguously describe their function, ie according to ñg la which refers to conversion from AC to DC, vs-ls conversion, according to Fig. 1b which refers to conversion from DC to AC, ls-vs-conversion, according to fi g lc which refers to a vs-vs-conversion, and according to fi g ld which refers to conversion from a direct voltage to another arm voltage.

The vs-vs converters which are used for carrying out the invention are referred to according to English terminology as "ac-to-ac bidirectional converters" and are explained in Webster's El. Eng. Handbook, Wiley 1999, under the section AC- AC POWER CONVERTERS, written by Rik W. De Doncker, Aachen University of Technology. The English term "converter" is translated into Swedish as alternating with converters, converters and converters. In this context, the term vs-vs converter is understood to mean conversion of frequency and / or amplitude. 'Converters for large effects are currently mostly made with silicon-based thyristors. These connections often require large reactive effects due to the fact that the currents of the VS network have a large phase shift relative to their voltages.

This means that the dimensioning a? machines for inverter-based systems and of inverters must take into account reactive power fl fates, ie reactive losses in machine and vs-network reactances and the need for phase compensation, thus not only the purely active power fl fates with more or less negligible active losses.

From a mechanical point of view, according to the state of the art, converters are built which are used in contexts which normally concern electrical machines, such as units, which stand next to the machine or are mounted on its stator. In recent decades, converters have begun to be mounted on the rotating parts, ie in or on the rotating part, for example as parts of a rotating brushless system for direct current magnetization of synchronous machines as below. In some contexts, converter-controlled rotor resistors also occur.

A converter connection that is very important in headline contexts is a connection according to Figure 1c, ie a connection that refers to frequency or vs-vs conversion. The function of a vs-vs converter can be accomplished in fl your different ways. A principled way is that the conversion takes place with vs-ls-vs- conversion, ie with ls intermediate. Another way is that the conversion is achieved with direct vs-vs conversion which can take place in different embodiments. Examples of such are conversion with so-called cycloconverters with mains-commutated double-current converters or with so-called nan-converters with self-commutated bi-directional power semiconductors.

Since in this context only the main functions as energy converters are relevant, detailed description and control, protection, regulation etc. of the rectifier and communication of signals to and from rotating parts will not be touched on in this publication. ^ Both in terms of generator operation and motor operation of AC machines, there is a well-known concept called synchronous speed. There is a clear relationship between the rotational speed of the rotor (n,, r / min), the pole number (p) of the machine and the frequency (fs, Hz) of the machine voltage.

The connection in synchronous operation is usually reported as: nr = (2 / P) 'fs' 60 (1) 20 25 30 40: _, V '', - _, m t. F. F,. , ß 51 t * rv ._ - <1 'I ~ <-1 (- ... 1. ..' - i. '_ f. _ ö' “The next part of the state of the art concerns the use of AC machines as electricity generator.

It is based on an electricity-generating unit in the form of an electricity generator and a drive device mechanically connected thereto in the form of a turbine, drive motor of some kind or the like. In order for the electricity generator to be able to be connected to a power grid and contribute to the power grid's electricity supply, it is required that the electricity generator's voltage, possibly via a transformer, is adapted to the power grid's voltage and that the frequency corresponds to the power grid frequency.

In order to achieve the desired and constant frequency, it is thus required, with a given pole number, that the unit rotates at a constant speed, which means that the drive device must have some form of control equipment for different load conditions and more. Varying water fate, drop height and mains commuting require both static and dynamic accuracy in the frequency control of hydropower generators.

Initially, a brief description will be given of how the excitation systems for electric generators rotating at "constant" speeds are designed according to current technology. This is done in part with so-called brushless magnetization with the help of a co-rotating feeder and agitator.

An example of a brushless feeder design can be found in the ABB brochure "Brushless exciter", SEGEN / HM 8-001. The brochure states that the feeder is an AC machine whose stator is provided with pronounced poles and whose rotor has a three-phase AC relief for feeding the above-mentioned inverters, preferably a six-pulse inverter bridge.

The DC DC voltage, ls, is then connected to the electric generator's field winding.

The voltage regulator of the electric generator takes place by influencing the supply's magnetization via its stator winding (field winding). Thus, having a co-rotating converter for vs-1s conversion and DC magnetization of the pole system of "constant" speed generators is known in the art. Figure 2 shows in principle how a brushless feeder is used in conventional electricity generators, ie with voltages up to 25 kV. Shown here is a vertical axis electric generator 1 which on the common shaft 2 is arranged with the generator of the electric generator with winding 3, the rotating alternator 4 of the feeder, co-rotating converter 5 and drive device in the form of a turbine 6. The stator 7 is via a step-up transformer 8 connected to a high voltage network. Figure 2 also shows the feeder's 10 20 25 30 35 in s r. ~ '»' - '_ f. v. f <- «_. .- _. f f <- u - ..

-V .-. . ~ a. f- _ _ m »<<< _ _ ff t ..,. «T. . Stationary field winding 9. Figure 3 shows a corresponding embodiment of the excitation system where the electric generator is designed as a high voltage generator according to WO 97/45919. No transformer for connection to a high-voltage network is then required. The reference numerals are otherwise the same as in Figure 2. Figure 4 shows the corresponding embodiment of the magnetization system where the electricity generator according to WO 97/45907 is designed as a high-voltage generator with 2x3 phase for supplying an HVDC system 10 with 12-pulse connection. The reference numerals are otherwise the same as in Figure 2.

A special embodiment of direct current magnetization of an electric machine rotating at a constant speed is described in a patent application PCT / EP 98/007744, for "Power fl ow control" in a transmission line. The stator windings of the electrical machine are here connected in series with the transmission line even conductor without interconnected neutral point. The rotor of the electric machine is equipped with two / three 90/120 degrees electrically displaced direct current rotor windings for regulating the amplitude and phase of the voltage of the electric machine. The rotor windings are fed via a co-rotating excitation feeder and converter / vs-ls converter for each of the rotor windings.

According to IEC 34-1 / 2, there are standardized permissible frequency and voltage deviations for electricity generators. In order to cope with the apparent rated power of the electric generator, the operating point of the electric generator must be within a so-called A-zone which is (largely) limited by +/- 2% in terms of frequency and +/- 5% in terms of voltage. However, the working point is allowed to be within a so-called B-zone which (largely) is limited by +3 and -5% in terms of frequency and +/- 8% in terms of voltage.

For conventional electric generators with DC-magnetized poles, as stated above, a given and fixed ratio applies between the frequency of the generated bias and the rotational speed of the rotor at a given pole number. Connecting an electric generator to a rigid power grid where the electric generator's synchronous speed / frequency deviates from the grid's frequency means significantly increased losses of the electric generator. If, for various reasons, a normally operating 50 Hz power triatt has a 2% lower frequency, a connected power generator will still operate at a synchronous frequency if the rotational speed of the rotor is 2% lower than the nominal speed. Although synchronous conditions can be obtained in this way under certain conditions, varying speeds of a connected electricity generator present major problems, especially as it can be difficult enough to allow the speed variations as large as technically and economically desirable +/- 10%. e .. 10 20 25 30 35 40 »A5 <1 ga 7 To solve these problems, the frequency control of electric generators with varying rotational speeds has had to be solved in other ways. For this purpose, according to the state of the art, there are various embodiments, a number of which are to be reported below.

In principle, one of the simplest ways to achieve the correct frequency for mains connection of an electricity generator, the speed of which varies within the limits stated above, is to connect a vs-vs converter according to figure 1c between generator and power grid. From an economic point of view, however, this is a very dubious design because the vs-vs converter must be dimensioned for full effect.

However, the embodiments which according to the state of the art have been used are mainly based on another principle known in electrical engineering for such machines, see for example the article in Hitachi Review mentioned below. shall generate a voltage with a frequency of 50 Hz. A typical hydropower plant is dimensioned for a base speed of 375 rpm and consequently, according to equation (1) has 16 poles.

If, for various reasons, the unit is driven by the turbine to rotate at 360 rpm, the synchronous frequency of the electric generator during direct current magnetization of the rotor poles according to equation (1) would generate a voltage with a frequency of 48 Hz.

If one designs the rotor winding as a vs winding and supplies this winding with a voltage with the difference frequency between the synchronous frequency f, at 360 r / min and the desired frequency 50 Hz, i.e. with fc = 2 Hz, the frequency of the electric generator will be fs = 50 Hz. In general, equation (1) is converted to n, = (Zlp) '(fs + fc)' 60 (2) where fc is the current difference frequency. A system for keeping the frequency of the electric generator constant must thus ensure that, regardless of the current speed of the drive device, the rotor winding is supplied with a voltage with the current difference frequency both in terms of sub-synchronous and su-synchronous operation. This principle is applied in different ways or with different embodiments.

Typical of known embodiments is that the rotor connections take place via three-phase slip rings, which transmit the entire shaft power or a large part thereof.

US 5,742.5 15, "Asynchronous conversion method and apparatus for use with variable speed turbine hydroelectric generation", describes a 10 “_ - n, v_f ~ <.c. f. ~ f. f- fr. _ _: w - -. t, <- r »_ f. > n o i. <C. _,. _. , free: r- ~ ff- N r K v, = K fr ': r' in hydroelectric power generation system that generates electric power to a power grid. In summary, the power generating part of the system can be described starting from Figure 5 where the components are plotted with the same symbol symbols and reference numerals as in Figures 2 to 4. The system includes, according to claim 19 of said U.S. patent, (to clarify the reference to U.S. Pat. the patent is used here as a hydro-turbine, generator, machine, etc. rotor winding 12 and a stator winding 13 of which the rotor winding or stator winding is connected to the hydroturbine unit and the other via a transformer 8 to the high-voltage power grid ...... .. ”. arranged with the rotor 3 of the hydrogenator with winding 3 and a rotating alternating current winding of a feeder 4. It does not appear from the figures or text in the patent whether the exciter power supply (fi g 1A, 62) is a co-rotating converter or whether the direct current excitation takes place via a stationary converter and transmission via two slip rings. In principle, these are equivalent solutions, but for comparison with other embodiments, it is stated in Figure 5 that the excitation takes place via a co-rotating converter 5. Figure 5 also shows the stationary field winding 9 of the generator and the stator winding of the hydrogenator 7. This part of Figure 5 is identical to Figure 5. 2.

From the description otherwise it appears that, in accordance with Figure 5, the stator power of the hydrogenator is transmitted via slip rings 14 on the rotary converter 11 to its rotor winding 12. The voltage induced in the stator winding 13 of the converter is connected via a transformer 8 to the power grid. The function of the converter 11 is thus to supply the system with the difference frequency which is necessary for the system to be able to supply a voltage with the correct frequency to the power grid at varying speeds of the hydromachine. In practice, this means that if the hydromachine rotates at its synchronous speed, the converter will be stationary, ie function as a stationary transformer. Depending on the current speed of the hydromachine, the rotor of the converter will thus need a drive source M / G 15 in the form of a motor or generator with vs-vs converter 16. It can thus be stated that the transformer 11 must be dimensioned for substantially the same power as the hydrogenator and that the slip rings must be able to transmit full power. The furnace former 11 rotates with the low difference in frequency, which means that the converter must have forced cooling with a large power loss.

The voltage regulation of a hydrogen generator 1 according to the US patent specification takes place by the above-mentioned direct current magnetization. The rotary converter 11 has leakage reactances in its rotor winding 12 and in its stator winding 13 which consume reactive power and cause voltage drops. These can be compensated by increased direct current magnetization in the rotor winding 3 of the generator or can, according to the application associated with the above-mentioned US patent EP 0749190 A2, be compensated by series capacitors. The EP application also shows that a typical rated voltage for the slip rings is 15 kV. The rated current for such a 100 MVA machine is thus about 4 kA and for a 300 MVA machine it is 12 kA. Consequently, a significant problem with such machines becomes to perform, utilize and maintain slip rings for these voltages and currents. 'ABB Review 3/1996, pp 33 - 38 reports a plant where "ABB Varspeed generator boosts efficiency and operating fl exibility of hydropower plant". The optimization is done by letting the turbine and electric generator run at variable speed. In order to still be able to connect the electricity generator to a power grid with a given and substantially fixed frequency, the frequency of the electricity generator is adapted to the mains frequency with the aid of a so-called sub / oversynchronous converter cascade. In order to be able to more easily compare this generator operation with the other reported embodiments, the current part of Figure 4 in the said ABB publication has been reproduced in Figure 6 and drawn with the same Figure symbols and reference numerals as in Figures 2-4 in the heading patent specification. Thus, here is a water-powered turbine 6 with an electric generator 1 (G2) for generating hydroelectric power. The electric generator 1 comprises a shaft 2 which is arranged with the rotor 3 of the hydrogen atom with winding 3. Figure 6 also shows the stator winding of the electric generator 7. The frequency adjustment to the current mains frequency takes place by means of the sub / synchronous converter cascade 17 (CC), which is cycloconverter / frequency converter.

The measurement to its mains side takes place via a transformer 18 (TR) and the current difference frequency is fed into the rotor winding 3 of the electric generator via slip rings 19. The voltage thus generated with the correct frequency is then fed via a transformer 8 to the power grid. One such frequency adjustment of an electric generator that is driven by a variable speed is a so-called Static Scherbius operation, see below under the presentation of the state of the art with regard to motor drives. e '' _. ~ ~. s. se -f-t: f 1. f; .- I. -, -_-. ;. ~ _ °. - z <. . . =. y _: z. r 1 - i - 1 * 'Nm t ... 4, ff (f. F. -> f .fi. R. F.,. <1 In order to be able to continuously and under different operating conditions the correct difference frequency is required, a frequency control system is required. the frequency control system ensures that the rotor of the converter rotates at the correct speed by means of a control signal 16a to the M / Gz control device and in the example shown in Figure 6, the frequency control system shall give the correct control signal 17a to the vs-vs converter 17.

However, the frequency control systems are outside the scope of this invention and will thus not be described in more detail.

For connection to a power grid, in addition to some form of frequency control, a voltage control to amplitude and phase angle is also required. In the same way as above, the voltage control systems are outside the scope of this invention.

Depending on the current control range, both in terms of frequency and voltage, in the case of slip-ringed alternating current machines, power will circulate internally via the circuit which includes the stator, rotor, slip rings, transformer and current grooves. The power dimensioning of these parts is also outside the scope of this invention, although a relative comparison between different embodiments will be shown during the description of the invention in order to demonstrate the advantages that embodiments according to the invention possess relative to the state of the art.

In SU 1746474 Al an "Asynchronized Synchronous Machine having Reversive Excitation System" is reported. This is an electric machine with conventional three-phase stator winding connected to a power grid. The rotor is equipped with galvanically separated phase windings. Each of these is connected to a co-rotating dual-current converter. These are made with thyristors and are fed from a co-rotating excitation feeder. The current meters are thus machine-commutated from the excitation magnet and are arranged so that they can supply the respective rotor windings with alternating current with a frequency which corresponds to the lag frequency of the machine. It is obvious that there are problems when changing the current direction in the rotor windings. In order to ensure the transition and to avoid large short-circuit currents when the excitation current is to change direction, a special coupling arrangement has had to be used for the connection of the double-current converters.

This consists in that each rotor winding is provided with an extra socket a number of winding turns from each end socket. - 20 25 30 35 _-. ' I * 'w 21 ”. ., ¿_ Z. r,. ._,. _ - -, «_ t 1 _ f 4, r e e <-. ._ a t i t.. i. »Nr: - uf- r f <nu 1« - _,, _ ,, -. . . ._. . «_ T..

In order to be able to adapt the frequency of a wind turbine's electricity generator to the frequency of a connected power grid at varying wind speeds, a brushless system, OPTI-SLIP®, was developed by Vestas Danish Wind Technol.

AIS, Denmark, described in an article “Semi-Variable speed operation-a comprorrxíse?”, Presented at the Proceedings of the 17th Annual Conference, British Wind Energy Association. 19-21 July 1995, Warwick, UK. The principle of the control is based on the well-known method of loss control by means of varying external rotor resistors connected via slip rings to the rotor winding of the electricity generator. Unlike the well-known slip ring method, the OPTI-SLIP® system is provided with a co-rotating vs-ls-ls converter and co-rotating fixed rotor resistors directly connected to the rotor winding. The Vs-ls conversion is performed with a diode rectifier, which in turn is short-circuited by an ls-ls converter.

The wind turbine's speed control takes place via an internal rotor current control.

The loss power associated with the control is thus developed in the co-rotating rotor resistor and then discharged to ambient air. The conference paper states that the speed can be up to 4% above the synchronous with the consequence that as many percent power is lost as losses in the rotor circuit.

Run-up of electricity generators to the current control area takes place in the same way as for constant-speed generators, ie the turbine accelerates the electricity generator to the area for possible synchronization.

The next part of the prior art deals with the use of alternating current machines as a variable speed motor with a more or less limited speed control range around one of the frequencies of the alternating current network and the number of synchronous speeds of the main machine according to equation (1).

Speed-controlled / -regulated motor drives have been around for about 100 years. The very first were so-called Ward-Leonard drives, ie DC motor drives. Somewhat later, various motor drives were added based on AC machines. These engine drives are often named after their respective inventors Kramer, Scherbius, Schrage m fl. Characteristic of these machines is that they are equipped with a wound rotor as well as brushes and slip rings or commutator.

It is also typical that they are arranged to return electrical power from the rotating parts to stationary system parts such as rotor resistors or that they are regulated with machines as actuators. 10 20 25 30 35 ~ j '_: b. << = r t »w' <,. - - .ax t., f .i. . . - _ - ,, - (_. .- i / r-. _., »(_. U (ut. .i _, _ _...,, _ ir. ._« After the advent of the converters, the interest in Speed-controlled motor drives' with alternating current machines have generally gained renewed relevance. the last decades often through so-called field vector regulation, ie division into fl fate and torque-forming currents.

The advent of converters has also meant that the classic Kramer and Scherbius drives, which follow equation (2) above, have gained renewed relevance - and are now often referred to as "Static Kramer" and "Static Scherbius", respectively. The renewed topicality mainly refers to motor drives with effects in the MW class. It is these engine drives that are most closely regarded as the state of the art relative to the invented invention. Des sa is described in a large number of writings, including briefly in IEE Proc, Vol. 131, Pt. A, no. 7, September 1984, pp. 535-536, "Electrical variable-speed drives", by B. L. Jones et al.

A static Kramer operation is most often referred to as a sub-synchronous converter cascade and has a basic connection according to Figure 7. The stator winding 20 of the horizontal-axis motor is connected to a power grid.

The rotor winding 21 is connected via slip rings 22 to a rectifier 23, the voltage of which becomes proportional to the lag. This voltage is connected to the voltage from an inverter 25 connected to the same power grid via a transformer 24. An inverter voltage is a trigonometric function of its control angle and in this way determines the speed of the motor.

In a static Kramer operation, in this way the lag effect is fed back to the grid by fi-sequence conversion in two steps via a direct current intermediate line.

In the case of an operation according to »fi gur 7, power can be transmitted only in one direction via rectifiers but in both directions if the rectifier 23 is designed as a converter with thyristors. To change the direction of rotation, the phase sequence of the motor connection needs to be changed.

A static Kramer drive can be characterized as a current-controlled motor drive.

A static Scherbius drive is shown in Figure 8. The motor's stator winding 20 is on. the same way as in Figure 7 connected to a power grid. The rotor winding 21 'is connected via slip rings 22 to a 13 cycloconverter / frequency converter 26, connected to the power grid via a transformer 24. The specificity of a Scherbius operation is that the speed is controlled via the rotor connector with the voltage of the cycloconverter whose core amplitude, phase and frequency can be changed independently of each other. The control requires feedback from the motor to maintain the correct frequency as well as the torque ratio and the phase ratio between rotor voltage and control voltage.

An advantage of the Scherbius operation relative to the Kramer operation is that the frequency converter can supply the machine with a rotor current even in synchronous operation, which means that the operation can be switched from sub-synchronous to su-synchronous operation without additional electronics. In addition, since the frequency converter is regenerative, a Scherbius drive can brake at both sub-synchronous and su-synchronous speeds. It can also operate continuously in synchronous operation without overloading the power semiconductors. However, the slip rings can be asymmetrically loaded with a certain risk of overheating when the operation is synchronous.

A static Scherbius drive can be characterized as a frequency and voltage controlled motor drive.

I Hitachi Review Vol. 44 (1995), no. 1, pp 55 - 62 describes a "400-MW Adjustable-Speed Pumped-Storage Hydraulic Power Plant" which is based on the Scherbius principle where the vertically axled speed-controlled alternator is used as a pump motor at night and as an electric generator during the day. Apart from the mounting direction of the shaft, the AC machine's basic design, coupling and functional description are thus the same as for fi guras 6 and 8. Interesting figures in this context are that in generator operation the rated power is 395 MVA at a speed range of 330 - 354 rpm and at the opposite word. 380 MW at a speed control range 330 - 390 rpm. The power of the required cycloconverter for these control areas is 72 MVA, ie it is between 18 and 22% of the respective rated powers.

The reported embodiments with slip rings and converters both in terms of electric generator and motor operation are subject to certain disadvantages / problems which the design intends to largely eliminate and reduce, respectively.

The main disadvantage of these drives, and which cause most problems and faults, are the slip rings and their connections, brushes, etc. These parts of an AC drive are those which have the shortest service life and require the most maintenance, especially as they are to transmit significant effects. iron, for example in the embodiment according to US 5,742.5l5, where the entire machine power is to be transmitted via the slip rings. 9 In slip-ringed AC machine operations, power circulates internally both in the stator circuit, the rotor circuit and the air gap, as well as via the external transformer and the vs-vs converter. The circulating effect can be both active and reactive. The reactive power is consumed internally in the transformer, in the converter and in the rotor and stator of the AC machine. This increases the type power of the electromagnetic circuit, ie the dimensioning product of rated voltage at idle and rated current at full load.

At the same time, this also means that the type power of the converters will be greater than what is needed due to the circulating reactive power.

The AC motor diets currently have a practical upper power limit of approx. 25 MW for various reasons. This is mainly due to the problems that arise in connection with starting and acceleration of the motor drives on relatively weak. power grid. If you were to start a synchronous machine with direct stargdvs with direct connection to the lqaf meter without trying to reduce the rotor currents in any way, the starting current could amount to 3 - 6 times rated current and the starting losses will mainly develop in the rotating parts where they are stored during the starting / acceleration process. adiabatic. In order to be able to start in a more controlled way, different procedures are used such as series / parallel connection of the stator windings, by means of a starting transformer or with a pre-connected reactor or resistor.

Starting of slip-ringed alternating current machines can take place with full stator voltage with rotor resistor RS connected to the rotor winding via the slip rings, which is gradually reduced when the machine starts. Such a starting device is shown in Figure 9.

Wrenching or deceleration of AC machines regler from the control range around synchronous speed to standstill according to the state of the art takes place in a manner well known to those skilled in the art. Braking is a transient process and, in the same way as starting, is associated with changes in the kinetic energy of the rotating system. The simplest electrical method of braking is the so-called counter-current braking, which takes place by changing two phases in the alternating voltage connected to the stator winding. The change in kinetic energy associated with the transient process causes loss of energy in the rotor circuit, which is therefore classically performed with slip rings and external rotor resistors to dissipate the loss energy from the interior of the AC machine in the same manner as at start-up. DISCLOSURE OF THE INVENTION, ADVANTAGES 9 As stated in the introduction, the invention consists of an electrically rotating AC machine whose basic embodiment comprises a main machine and a control machine with a common mechanical shaft and a converter rotating with the shaft. The invention also includes a method of using the co-rotating inverter.

Characteristic of the main machine is that it is designed with windings in both stator and rotor and that it can work both as an electric generator and motor.

The control machine has funktioner your functions. It shall provide the rotor winding of the main machine with control power / frequency for the current control range and it shall also be able to function as a starter motor for the constant frequency machine or be able to transmit the main losses of the main machine to external resistors. .

The converter also has fl your functions. Its main task is to function during operation as a vs-vs converter according to the previously given definition. v During start-up, it must be able to function as a VS-phase phase switch or as a VS phase angle / voltage regulator or as a VS short-circuit switch for the rotor winding of the control machine. During controlled firing and / or stopping, the inverter must be able to function as a vs-phase angle / voltage regulator or as a vs-fl phase switch. The invention also includes a method of using the co-rotating inverter in accordance with the above.

The system designs when the machine works as an electric generator or motor, however, differ somewhat mainly in terms of rated effects, rated voltages and starting methods. In some contexts, however, the machine can be used both as an electric generator and a motor.

Initially, the disclosure of the invention deals with the design of the stator winding of the main machine, which is broadly common to the machine both as an electric generator and a motor. Then follow a description of the machine when it is used as a variable speed electric generator and when it is used as a motor with varying speeds. Then the design of the control machine and also to some extent the vs-vs converter is described in broad outline. Finally, the advantages which a machine according to the invention possesses are stated relative to the state of the art. 10 '20 25 30 35 _-, - i, _. -._ «_ '' - '_: árh f.: _ Ff H -« _c.; R r z «« I -', r r <.ce <i _ va »<~ <. U-v. _ _ .r. f <r _. t. 16 It has been stated in general terms above that the stator winding of the main machine is connected to a transmission or distribution power network with medium or high voltage. The connection can, as stated on the enclosed urer gures, be transformerless or via power transformers. The connection can also be made to converters for frequency conversion, for phase compensation, for filtering harmonics, etc.

For direct connection to a high-voltage network, the stator winding of a machine according to the invention is wound with a high-voltage cable. A preferred embodiment of the cable comprises a live conductor consisting of transposed, both uninsulated and insulated, strands. Around the conductor there is an inner semiconducting layer which is surrounded by at least one extruded insulating layer which in turn is surrounded by an outer semiconducting layer. To avoid induced currents and associated losses in the outer semiconductor layer, this is divided into a number of skimming parts. Each of these scum parts is then connected to earth, the outer semiconductor layer being focused on earth potential or at least close to earth potential. This means that no large randomly distributed, with the conductor geometry varying electric field concentrations can occur at the stator winding of the machine. A fuller description of such a cable and winding as well as the advantages which such a cable and winding allows in rotating machines is given in WO 97/45919.

As stated above, the description of the invention must first describe how the machine will be used as an electric generator with varying. speed. An exemplary embodiment of the basic embodiment is shown in Figure 10 which, as far as generated voltage is concerned, refers to a conventional electricity generator, ie an electricity generator intended for voltages up to 25 kV. In order to be able to easily compare the invention with the state of the art reported, Figure 10 has as far as possible the same symbols and reference numerals as previously reported figures. There is thus a main machine / electric generator 1, a control machine 27 arranged on a common shaft and a converter 28 mounted on the shaft in the form of a vs-vs converter. Figure 10 otherwise shows that the AC machine's rotor winding 29 of the control machine is connected to the "mains side" of the vs-vs converter and that its output is connected to the AC rotor winding 3. The control machine's stator winding 30 can be designed in the same way as previously mentioned brushless feeders. . As can be seen from the following report, another design can also be used. The main machine / generator and the control machine are driven in the manner previously described via a turbine 6. The voltage generated by the generator generated in the stator winding 7 is connected as above via a step-up transformer 8 to a high voltage power grid.

The principle of the frequency control at varying speeds on the drive device is the same as previously reported, ie that the voltage generated by the alternator 3 of the electric generator is supplied with a voltage with the difference frequency needed to obtain the desired frequency of the generated stator voltage at the current speed. The control signal 28a of the frequency control system to the rotary vs-vs converter can be created in various ways outside the scope of this invention. The same applies to the system's voltage regulation, in terms of amplitude and phase angle.

It should be noted that when the electric generator is operated at a speed which, with a given pole number, corresponds to synchronization to the frequency of the power meter, the connection of the vs-vs converter to the rotor winding will take place with the frequency zero, ie with direct current. In contrast to the state of the art with slip ring transfer of power / difference frequency to the rotor winding and in contrast to the special coupling of the rotor winding with galvanically separated windings with extra sockets required with the machine-commutated dual converter 'reported in SU 1746474 A1, transmission according to the invention now takes place power / difference frequency to a conventional rotor winding with a self-commutated double-converter which in a preferred embodiment consists of a matrix converter. Since it is now a question of power transfer to / from the power grid, the control machine and converters must be dimensioned for the current control range both in terms of torque and speed as well as in so-called commutation overlaps due to the "weak grace nature of the rotating windings. To illustrate this, in contrast to Figure 2, 3 and others where the feeder is only to supply the electric generator with direct current magnetizing power, the control machine 27 has been drawn more proportionally correctly relative to the power of the electric generator.

Problems related to inverter commutation can be reduced in various ways. ABB Review 2/97 pp 25-33 describes a method with "Capacitor commuted converters for HVDC systems". The article describes how the commutation margin is improved and how the reactive power demand decreases with series capacitors in the vs connection, ie between the mains-commutated converter and its transformer, when the converter operates in plant hitter operation. A corresponding technique is used in connection with the description and execution phonographs of the vs-vs converter integrated in the invention.

The variable frequency machine with variable speed according to the invention can of course be designed for adaptation to different generating application alternatives. This applies in particular to both the winding designs of the main machine and the control machine and thus also to the design of the vs-vs converter. As an example of alternative embodiments with regard to the stator winding of the electric generator, it can also, in addition to the embodiment shown in Figure 10 for "conventional" high voltage level as far as electric generators are concerned, be designed as the electric generator reported in WO 97/45919 for even higher voltages according to an equivalent to Figure 3. Figure 11b shows an axial end view of a sector / pole division of a main machine according to the invention and will be described in more detail during the description of embodiments. The equivalent of Figure 4, ie where the electricity generator is designed as a high-voltage generator according to WO 97/45907 with 2x3-phase stator windings for supplying an HV DC system with I2 pulse voltage, is also a highly current embodiment.

Running up / starting of the constant frequency machine to the current control area for operation as an electric generator takes place by the turbine accelerating the main machine and control machine until the machine itself can take over the control.

An alternator according to the invention also has a large, application range for motor drives with varying speeds. A basic design with regard to motor drives shall be described on the basis of Figure 12.

In the same way as stated for the exemplary embodiment of the basic design of the electricity generator, here too, for comparison of the invention with the state of the art reported, the same urs gur symbols and reference numerals shall be used as far as possible in previously reported urer gurms with regard to motor dips, ie fi guras 7 and 8. Thus, according to Figure 12, there is a main machine / electric motor 1 with a stator winding 20 and a rotor winding 21, a control machine 27 arranged on a common axis and a converter 28 in the form of a vs-vs converter. The control machine is provided with a rotor winding 29 and a stator winding 30. Figure 12 also shows that the rotor winding 29 of the control machine is connected to the "mains side" of the afsssvee 19 vs-vs converter and that its output is connected to the main machine / electric motor's alternating current. rotor winding 21. The stator winding 30 of the control machine can, in the same way as previously mentioned brushless feeders, be designed with pronounced poles, but here too other embodiments can occur. The electric motor and the control machine jointly drive the mechanical load (not shown).

The principle for varying the speed of motor drives during alternating current supply with "constant" mains frequency is the same as previously reported for electric generators, ie according to Figure 12 the AC rotor winding 21 of the main machine is supplied with the difference frequency needed for the currents in the stator winding 20. The 29 mrnk and fl fate waves must rotate synchronously in the electric motor's 1 air gap.

The control signal 28a of the speed / frequency control system can be created in different ways.

It depends on requirements for dynamics, power factor, the level of the mains voltage relative to its nominal, etc. In the same way as for synchronous operation of the electric generator reported above, the current in the rotor winding 21 of the electric motor 1 has the frequency zero during synchronous operation, ie there will again be a special case with direct current in the rotor winding of the main machine.

In describing the invention in terms of both generator and motor operation, it has been stated that the rotor winding of the control machine shall be an alternating current winding and that the stator winding may be designed with pronounced poles, but that other embodiments may be relevant, depending on different applications. The next part of the report describes alternative embodiments.

The control machine creates a local AC network to which only the vs-vs converter is connected. Its pole number can thus be chosen relatively freely.

In order to keep its physical dimensions as small as possible for a given speed variation, the control machine is preferably made with more poles than the main machine.

The design with pronounced poles can also take place in different ways. The preferred embodiment consists of "pronounced poles" with a direct current winding. This creates a stationary air gap fate in the control machine that allows a facility-critical control option by varying the size of the air gap fate via the value of the direct current. The embodiment of distinct poles in the stator of the control machine also comprises that the air gap fl fate is created by permanent magnets, which, however, means a substantially constant 10 15 20 25 30 35 40 Å f: Cl i | f. t- I * ~ - l luftgaps fl öde. The design with pronounced poles of the stator of the control machine is mainly relevant when the invention is used in various generator operations.

The stator winding of the control machine can also be designed as an alternating current winding, whereby a rotating air gap flow is created in the control machine. Such an embodiment mainly allows the supply of excitation power during operation, however, combined with a certain input / output of shaft power. This can be eliminated by feeding direct current into a part of or by switching the alternating current winding. Another great advantage of an AC winding in the stator is that the starting conditions are significantly improved when the machine according to the invention is used as a motor.

The vs-vs converters which, according to the state of the art, are used in connection with speed control via supply varying frequency have a constant infrequency determined by the electric power grid. A machine according to the invention places higher demands on the vs-vs converter. This is because the input / frequency of the vs-vs converter, which is generated by the rotor winding of the control machine, varies and is, for a given machine design and electric power grid, dependent on and directly proportional to the variable / varying speed of the shaft. In addition, the output voltage / output frequency of the vs-vs converter to the rotor winding of the main machine in terms of frequency shall be proportional to the difference in speed between the synchronous of the main machine and the current speeds. This means that the ratio between the input and output frequency of the vs-vs converter will vary.

The design of the vs-vs converter integrating in the invention and. Incoming components will be described in more detail in the description of embodiments. In general, the vs-vs converter can be designed as a matrix converter or as a cyclo-converter, ie a voltage-rigid direct converter with anti-parallel-connected thyristor bridges.

The Vs-vs converter can also be made with DC or DC intermediates. It must be dimensioned so that it can withstand the largest occurring idle voltage and the largest possible load current in the rotor windings. 20 25 30 35 40 2 :: ;; ¿. 21 'AC machines according to the invention have a significant number of advantages over corresponding drives designed according to the state of the art: Control / regulation of the AC machine takes place without a brush.

Since these brushless AC machines do not circulate power around via the stator circuit, this roughly halves the required converter power.

An AC machine according to the invention can be used both as motor and generator for generating reactive power to the power grid or at least not draw any reactive power from the machine.

Power electronic converters reduce the losses and physical size of the main circuits. Since neither active nor reactive circulating power loads the winding of the stator, the losses will also be significantly reduced relative to the prior art.

Both the rotor windings of both the main machine and the control machine can be made with lower and thus cheaper voltage levels, since there are no longer any limiting, external criteria from slip rings, wide rail tracks and cabling. Harmonics in the converter circuits remain substantially inside the rotating machine and thus do not propagate to the power grid.

The machine can be designed for one, two or two of your high-power feeders. ^ To further report the advantages of a constant frequency machine with varying / variable speed according to the inventory, a relative power comparison is shown in the following table based on a given apparent rated power Sn for the reported embodiments. The introduction refers to the sum power for the rotating machines, ROT, sum power for the input transformers, TRAFO, sum power for the input converters, SR, the sum of via_ 10 20 25 30 35 40 5 i =: r n,. f: in 22 slip rings Transmitted power, SL and output power, UB. (T.S.) and (U.F.) respectively means that the uren gure belongs to the state of the art or the invention.

Machine according to ROT TRAFO SR SL UE Figure 2 (TS) Sn Sn 0.05 Sn 0 Sn Figure 3 (TS) Sn 0 0.05'Sn 0 Sn Figure 5 (TS) 2.2 Sn Sn 0.2 Sn 1, 15 Sn 1.1 Sn Figure 6 (TS) 1.3 Sn 1.4 Sn 0.4 Sn 0.4 Sn 1.1 Sn Figure 9 (UF) 1.3 Sn Sn 0.3 Sn 0 1.1 Sn Figure 10 (U .F.) 1.3 Sn 0 0.3 Sn 0 1.1 Sn Machine according to Figure 2: All “larger” manufacturers of electric generators can manufacture _ constant-speed machines with a full-power step-up transformer with a brushless feeder. In a plant according to fi guren, the electric power generator 1 and the step-up transformer 8 are designed for the same apparent rated power Sn.

The standard concept for a plant is to use a co-rotating feeder with current converter / vs-1 converter 5 for feeding the field winding 3 in the rotor for the brushless design. The type effect of the inverter becomes to some extent dependent on the dynamic requirements of the voltage control. Typical values, however, are that it is dimensioned for 5% of the electricity generator's power. The machine has no slip rings for transmitting the direct current magnetization to the field winding.

Machine according to Figure 3: This is a machine according to previously reported WO 97/45919, ie an electric generator 1 for high voltage where the system does not need a step-up transformer. The type effect of the co-rotating current generator will be as above, ie about 5% of the apparent rated power. The magnetization can take place without slip rings. In Machine (s) according to Figure 5: An estimate of the sum of the apparent rated power of the rotating machines indicates that it is approx. 2.2 'Sn. Without specifying the basis for this assessment, it can be stated that since the machine / switch 11 must have the rated power Sn, as well as the transformer 8, machine 1 must be dimensioned for the same power plus the reactive power that machine 11 consumes. The sum of the power of the rotating machines must also include the power consumed to drive machine 15, i.e. the drive source of the converter.

Total converter power for the vs-vs converter 16 and for DC magnetization of machine 1 is estimated at about 0.2 'Sn.

Total power through the slip rings is the apparent power transmitted from machine 1 to machine 11, which is estimated to be about 1.15 'Sn based on a short-circuit reactance of machine 11 of 0.15 pu. The series capacitors mentioned in EP 0749190 also have the value 0.15 pu. As previously reported, very high demands are placed on the power transmission capacity of the towing ring.

Machine according to Figure 6: As previously reported, this is a system based on the Scherbius cascade where the rotating electric machine / generator 1 is assumed to be made with slip rings 19 to the cascade. The Vs-'vs converter 17, ie the converter in the cascade, is dimensioned for the current control range and for the reactive power it consumes. The installed rated power of the converter can thus be estimated at about 0.4 'Sn, which also corresponds to the total power through the slip rings. The apparent rated power of the rotating machine will consequently be about 1.3 'Sn and the total installed rated power of the transformers about 1,4' Sw Machines according to Figures 10, 11a and 11b: These figures represent a machine according to the classified invention, ie a with variable / variable speed ”. Together-. In essence, the machine comprises a first electric machine 1 called main machine and a second electric machine 27 called control machine with a common mechanical shaft 2 and a co-rotating converter / vs-vs converter 28.

According to Figure 10, the main machine 1 can be designed with a "conventional" high voltage for electric generators, ie up to 25 kV and a step-up transformer 8, or it can be designed according to Figure 11a with high-voltage winding, eliminating the step-up transformer. Since reactive power does not circulate intimately via the stator of the main machine, the type power of the vs-vs converter for the same control range as for the machine according to fi gur 6 becomes smaller, approximately approx. 0.3 'Sn. Consequently, the rated power of the control machine also becomes 0.3 'Sn and the total apparent rated power of the rotating machine is 1.3' Sn. The rated power of the transformer 8 in 10 gur 10 becomes 1.0 'Sn.

Machines according to the invention thus do not comprise slip rings. A constant frequency machine according to the invention has, in contrast to the embodiments reported in the prior art, an advantage which means that the starting and acceleration conditions are significantly improved. It has previously been reported that the stator winding of the control machine can be designed as an alternating current winding to allow, for example via an auxiliary winding in the stator of the main machine, the supply of magnetizing power for the control machine during operation. It is also suggested in this context that an alternating current winding in the stator of the control machine improves the starting conditions when the constant frequency machine is used as the motor. If the stator winding of the control machine is designed as a three-phase winding, external variable resistance can be connected to the connections of the winding during the starting process to control the size of the starting current and to mainly resistive phase angle and to remove losses of the main machine. This can be done by connecting the inverter as a vs- fl phase switch. In principle, starting can also take place in such a way that the stator winding of the control machine is connected directly to a power grid and that the rotor winding of the control machine and main machine is via the converter. connected and that external variable resistor is connected to the stator winding of the main machine. By controlling the co-rotating diffuser as a phase-angle / voltage regulator during the starting process, the external resistance can be a fixed resistance. Both the main machine and the control machine operate in such connections as rotating transformers. A more detailed description of starting connections will be presented in the description of embodiments.

For a normal speed control range and normal capacitance for reactive power of the constant frequency machine, the control machine is rated for about 30% of the power of the main machine. This allows an opportunity to use the control machine at start-up as a starter motor whose stator winding is fed from a separate frequency converter. A prerequisite is then that the co-rotating converter is connected as a VS short-circuit of the control machine's rotor windings. Such a connection will also be reported in the description of embodiments.

These alternative starl methods mean that the upper power limit for motor drives when starting on weak power grids can be increased to at least 40 MW. 10 20 25 30 35 40 25 Technically, the stator and rotor windings of the main machine with the respective stator and rotor cores function as a unit that OO creates torque and rotary motion adjusts incoming high / medium voltage to medium / low voltage which is optimal for both the co-rotating the vs-vs converter as the control machine forms a "step-down" power transformer between the mains and the power electronics with high voltage cable in the stator can have a conversion ratio between the stator bias and the rotor bias that can amount to 100 - 300 times without capacitively causing high frequency amplifications The electric power meter or auxiliary power winding occurs with the windings and cores of the main machine, filters the undertones / harmonics generated in the vs-vs converter and faces the main machine in current, thus preventing them from being transmitted to the mains via the stator winding of the main machine.

Technically, the stator and rotor windings of the control machine with the respective stator and rotor cores function as a unit that 0 via a suitable selection of pole numbers creates a higher frequency, 50 - 150 Hz, than the supply power grid and thereby in normal operation provides conditions for a good sine shape for the rotor current of the main machine generated via the vs-vs-converter with the windings and cores of the control machine during normal operation filters the undertones / harmonics generated in the vs-vs-converter and facing the control machine and thus prevents them from being transmitted via the stator winding of the control machine and the auxiliary voltage winding on the main machine to the electric power meter and via the stator winding of the control machine to the external supply source 10 20 25 30 35 _. "0 in transient processes such as start and controlled braking and stopping acts as a" rotating transformer "which leads the associated losses from the rotating parts of the main machine to external resistance.

A description of the technical functions of the co-rotating inverter is presented under the description of embodiments.

DRAWING LIST Figure 1 shows block diagrams of the converters that appear in the description.

Figure 2 shows in principle how brushless feeders for direct current magnetization are used in connection with conventional electricity generators, ie with voltages up to 25 kV. Figure 3 shows in principle how brushless magnetization feeders are used in connection with electric generators invented according to WO 97/45 9 19, ie with even higher voltages.

Figure 4 shows in principle how brushless magnetization feeders are used in connection with electric generators designed according to WO97 / 45907, ie as a high-voltage generator with 2x3 phase for feeding an HVDC system.

Figure 5 shows in principle the electric power generating part of a plant as shown in US 5,742.5 15, "Asynchronous conversion method and apparatus for use with Variable speed turbine hydroelectric generation".

Figure 6 shows in principle the electric power-generating part of a plant which appears from an article where "ABB Varspeed generator boosts efficiency and operating fl exibility of hydropower plant".

Figure 7 shows in principle how a 'static Kramer operation is designed.

Figure 8 shows in principle how a static Scherbius operation is designed. Figure 9 shows how external rotor resistors are connected to the rotor winding via slip rings during a starting process.

Figure 10 shows a basic embodiment of a machine according to the invention used as a power generator for conventional high voltage, ie for voltages up to 25 kV.

Figure 11a shows a basic embodiment of a machine according to the invention used as an electricity generator designed according to WO 97/45919, ie with even higher voltages.

Figure 11b shows an embodiment of an axial end view of a machine according to the invention used as an electric generator for high voltage corresponding to machines according to WO 97/45919.

Figure 12 shows a basic embodiment of a machine according to the invention used as a motor for conventional high voltage, ie for voltages up to 25 kV.

Figure 13 shows a basic circuit diagram for both the windings of the main machine and the control machine with the co-rotating current relic in the form of a matrix converter with double-hinged valves.

Figure 14 shows examples of alternative bidirectional controllable / extinguishable valves.

Figure 15 shows a basic circuit diagram for the windings of both the main machine and the control machine with the co-rotating converter in the form of a voltage-rigid direct converter with antiparallel-connected thyristor bridges.

Figure 16 shows a basic wiring diagram for the windings of the main machine and the control machine as well as an indication of the various functions of the co-rotating converter.

Figure 17 shows a basic circuit diagram for the windings of the main machine and the control machine as well as an indication of the function of the co-rotating converter when an external variable resistor is connected to the stator winding of the control machine. '20 25 30 35 40 1514; "g:» iíí flíï i i 'Figure 18 shows a basic circuit diagram for starting with external resistance connected to the stator winding of the control machine and with the current converter in the form of a matrix converter used as a water phase switch.

Figure 19 shows a basic wiring diagram for starting with external resistance connected to the stator winding of the control machine and with the stirrer in the form of anti-parallel thyristor bridges used as a reverse phase coupler.

Figure 20 shows a starting connection of the main machine with the control machine as the starter motor whose stator winding is fed from a separate frequency converter.

Figure 21 shows how the stator of the main machine is provided with a winding for auxiliary voltage supply of the stator of the control machine.

DESCRIPTION OF EMBODIMENTS The power electronics included in the constant frequency machine according to the invention for the main function are located in the rotating parts of the machine.

Optimal voltage levels in the windings of the rotor circuits are determined, independently of the mains voltage, mainly by the maximum permissible voltage levels of the power semiconductors and the current connection, as well as with and without series-connected semiconductors. With regard to the stator winding of the main machine, however, there are no such limitations. It can therefore be manufactured for direct connection to high-voltage electric power meters. This is made possible by the stator winding being manufactured / wound with high-voltage cables, among other things according to WO 97/45 919. The laminated magnetic circuit of the stator must therefore first be described on the basis of the use of high-voltage cables in the stator winding.

Examples of embodiments of an axial end view 31 of a sector / pole division of a main machine according to the invention for high voltage are shown in 11b. Each sector / pole division is composed in a conventional manner of sector - shaped electrical sheets. The stator of the machines will thus consist of a number of sectors / pole divisions which together form a laminated stator core.

From a radially outermost back portion 32 of the core, a number of teeth 33 extend radially towards the rotor. Between the teeth there is a corresponding number of grooves 34. The use of the above-mentioned high-voltage cable 35 means, among other things, that the depth of the grooves for high-voltage machines is made greater than what has been required - according to the state of the art. The groove has a cross-section stepped towards the rotor as the need for cable insulation becomes lower for each winding layer towards the rotor. As can be seen from the fi guren, the groove consists essentially of a circular cross-section 36 around each layer of the winding with narrower waist portions 37 between the layers. Such a track cross-section can with some right be referred to as a "bicycle chain track". Since such a high voltage machine will require a relatively large number of layers and the availability of current cable dimensions in terms of insulation and outer semiconductors is limited, it can in practice be difficult to achieve a desired continuous phasing of the cable insulation and stator groove. In the embodiment shown in Figure 11b, cables with three different dimensions are used on the cable insulation, arranged in three sections 38, 39 and 40 dimensioned accordingly, ie in practice you will have a modified cycle chain track. The också gure also shows that the stator tooth can be designed with a practically constant radial width along the entire depth of the groove. The stator may be provided with a winding 41 for auxiliary power supply, for example for the stator winding of the control machine.

Since the rotor is also provided with a vs-winding, its core will consist of a, with a track number slightly different from the stator, design of a number of laminated sectors / pole divisions with rotor grooves 42 for the rotor winding 43. The rotor winding must be fed from vs-vs- the converter 44 with a voltage with the current difference frequency. The voltage dimensioning of the rotor winding is then mainly determined by the highest permissible voltage levels in the power semiconductors included in the vs-vs converter.

This in turn determines the design of the rotor winding. It can thus be designed according to known technology for conventional high / medium shielding machines or as the one mentioned above with high voltage cable, ie according to WO 97/45919.

The co-rotating vs-vs converter 44 shown in Figure 1a must be able to convert the relatively high frequency, 50 - 150 Hz, of the voltage generated in the rotor winding of the control machine to the difference frequency, 0 - 10 Hz, depending on the current control range. If the converter is made with silicon-based power semiconductors / valves with a valve I in the branches of the converter, the rotor windings of the main machine and control machine will be dimensioned for 1 - 3 kV. If the converter is made with silicon carbide-based power semiconductors / valves with a valve in the branches of the converter, the corresponding voltage levels will be 10 - 30 kV.

Dimensioning in terms of voltage for the rotor windings of the main machine and control machine becomes access to, selection of and connection, ie without or with series connection, of power semiconductors for 20 25 30 35 40 i: is 1 :: = ;; in the 30 vs-vs converter.

Figure 13 shows a basic circuit diagram for the windings of both the main machine and the control machine with the co-rotating vs-vs converter in the form of a matrix converter with bidirectional valves. In the example shown, both the stator winding 45 of the main machine and the rotor winding 46 are drawn as Y-coupled three-phase windings. The matrix converter 47, with the necessary shunt capacitors to create a high-frequency low-impedance loop where the current can easily commutate between the phases in the rotor winding of the control machine, is connected between the AC rotor winding of the main machine and the AC rotor winding 48 of the control machine.

The above-mentioned "commutation overlaps due to the" weak network "character of the rotating windings" are eliminated with the matrix converter and its in shunt capacitors. The control machine can thus be designed for lower type power.

The stator winding 49 of the control machine is shown in the embodiment shown as a three-phase winding.

Figures 14a, 14b and 14c indicate alternative bidirectional valves in the matrix converter. The following identification requires some expertise.

Figure 14a shows a bidirectional valve in the form of two GTO thyristors or two IGCTs. Figure 14b shows a bidirectional valve with two IGBTs. Figure 14c shows a bidirectional valve with an IGBT.

Figure 15 shows a basic circuit diagram for the windings of both the main machine and the control machine with the co-rotating vs-vs converter in the form of a voltage-rigid direct converter with antiparallel-connected thyristor bridges. In the same way as in Figure 13, both the stator winding 45 of the main machine and the rotor winding 46 are drawn as Y-coupled three-phase windings. The voltage rigid direct converter with anti-parallel thyristors 50 is connected between the AC rotor winding of the main machine and the AC rotor winding 48 of the control machine.

In the same way as for the matrix converter, in order to facilitate the commutation, capacitors can also be connected in series or shunt between the rotor winding of the control machine and the vs-vs converter and between the rotor winding of the main machine and the vs-vs converter. They can also be connected in series and / or in parallel to internal sockets inside the rotor winding of the control machine. Connection of capacitors in this way means that the control machine can be designed for lower type power. In the embodiment shown here, the stator winding 49 of the control machine is also shown here as a three-phase winding. As has been mentioned previously, within the scope of the invention there are a number of different alternative embodiments for both the windings of the main machine and the control machine.

In the case of the stator winding of the main machine, a preferred embodiment is a three-phase winding such as that shown in Figures 13 and 15, i.e. a conventional Y-coupled winding. When the machine is relevant in an HVDC system, the stator winding will be designed with 2x3 phase winding with a 30 degree phase shift, as shown in Figure 4. Other winding forms, eg 1-phase, 2-phase and fl phase, 2x2 phase m fl can become relevant for specific purposes. As far as the voltage level of the stator winding is concerned, the machine can be dimensioned for conventional "machine" high voltage, ie up to 25 kV, or it can be dimensioned with high voltage cable for significantly higher voltages. In certain application contexts, the stator can be provided with an extra winding for generating auxiliary power for, for example, the control / regulation of the control machine, etc., which is shown in Figure 21, among other things.

In a preferred embodiment, the AC rotor winding of the main machine is also a Y-coupled three-phase winding, as shown in Figures 13 and 15. Here too, for various reasons, the three-phase winding can be D-connected, the winding can be designed as a 2x3 phase winding and other previously mentioned winding shapes may be relevant. Also with regard to the AC rotor winding of the control machine, the Y-coupled three-phase winding shown in Figures 13 and 15 is a preferred embodiment, but can be made D-coupled or with eg 1-phase, 2-phase and fl phase, 2x3-phase, 2x2-phase m fl. The Vs-vs converter can also be supplied with single-phase alternating current from the rotor winding of the control machine. Other winding shapes may be relevant in connection with specific applications.

Figures 13 and 15 show that the stator winding of the control machine can also be designed as a Y-coupled three-phase winding. As mentioned earlier, the stator of the control machine can be designed with pronounced poles for direct current magnetization and it can also be designed with permanent magnets. Although the stator winding consists of a three-phase winding, it can be used for direct current magnetization via a certain circuit. The design of the stator winding of the control machine is often determined by how the machine is to be started from a standstill up to the current speed range. 20 25 30 35 40 32 Common to current applications with the constant frequency machine is that the load only needs a limited control range around the synchronous speed of the main machine.

An AC machine according to the invention has a large number of application areas in terms of motor drives. There are processes with motor drives which for various reasons do not currently use speed control but which with AC machines according to the invention could be significantly improved.

The machine's stator winding can be dimensioned for connection to the power supply network with voltage from established low voltage up to classic high voltage levels. Determining the current voltage on the stator winding is largely available mains voltage and current effector wire.

For motor powers of single megawatts, the stator winding is preferably connected to an intermediate voltage level between 1 and 36 kV.

At rated powers above 10 MW, the machine's connection to the supply network can preferably be dimensioned for 50 kV or higher, eg 130 kV, ie connected to the transmission and distribution network. By connecting to these mains voltage levels, above all, high current forces and voltage drops in the power grid during the starting process are avoided.

As mentioned in the preamble to the description of the invention, the co-rotating inverter can be connected to your various functions.

In addition to the function as a vs-vs converter during operation, it can also be connected for funktioner your functions in connection with the start and controlled stop of the constant frequency machine. Figure 16 shows the preferred embodiment with regard to the design of the windings in an operational summary of the functions of the converter 51 both during operation, start and stop. Controlled firing and stopping are described later. The functions of the inverter at regulated operation and start are as follows: 0 The function 51a of the inverter corresponds to its function during operation, ie as a vs-vs converter according to the previously given definition. The function of the rectifier Slb corresponds to its function during start-up as a phase coupler which electronically interconnects input and output connections for interconnecting the rotor windings of the main machine and control machine 20 when external variable resistor 52 is connected to the stator winding of the control machine according to Figure 17. 5 lc corresponds to its function during start-up as vs-phase angle / voltage regulator between the rotor windings of the main machine and the control machine when external fixed resistance is connected to the stator winding of the control machine. The function 5 ld of the converter corresponds to its function during start-up as a vs short-circuit coupler of the rotor windings of the control unit when directly connecting the stator winding of the control machine to a power network according to 1 gur 1 8.

Figure 18 otherwise shows a basic wiring diagram for starting the constant frequency machine by direct connection of the main machine to a power grid. Start takes place in the manner previously mentioned with external three-phase controllable resistor 52 connected to the three-phase stator winding of the control machine. The starting losses of the main machine are now transformatively connected to the control machine, which then transmits the losses to the external resistors via its stator winding.

The function of the inverter when it is to function as a v-phase coupler can be achieved in different ways. Figure 18 shows in detail how the converter is arranged as a phase switch with a matrix converter. This function is obtained by "lighting" a valve, the coarsely marked one, in each branch. Figure 19 shows the function as vs- fl phase coupler with the converter in the form of in “antiparallel connected thyristor bridges 50a and 50b. As can be seen, it is now convenient that the rotor winding of the main machine consists of 2x3 phase windings 46a i and 46b for 6-pulse connected thyristor bridges where each bridge needs to be provided with a pair of antiparallel-connected, coarsely marked thyristors and with corresponding rotor windings 48a and 48b of the control machine.

For a normal speed control range of the constant frequency machine, the control machine is dimensioned for about 30% of the power of the main machine. This allows an opportunity to use the control machine as a starter motor at start-up. whose stator winding is fed from a separate, non-co-rotating, frequency converter 53. A condition then is that the co-rotating converter is 40 v, connected as a vs-short-circuit coupler, ie as the function 51d, of the rotor windings of the control machine. Such a starting connection with the drive 53 is shown in principle in Figure 20.

Controlled combustion from the control range to stationary is performed with the same main circuits as for start, ie as ur guras 18 and 19. The co-rotating converter is used as 0 vs- fl phase coupler, ie as 5 lb above, between the main machine and control machine rotor windings for controlling active and reactive effect by direct interconnection of the windings with and / or without shifting of the phase sequence. The process is carried out by so-called countercurrent braking and the power development associated with the transient process takes place in externally variable resistor 52. In addition, a change of phase sequence may take place at the alternating voltage connected to the stator winding of the main machine or as the resistance is fixed and the control takes place through the proportion of the alternating current of the rotor circuit that is passed through. Here, too, a change of phase sequence must take place at the alternating voltage connected to the stator winding of the main machine. 6 a vs short-circuit coupler, ie as 51d above, for controlled bridging by means of a frequency converter 53 in fi gur 20. Change of phase sequence for the connection to the stator winding of the control machine from the frequency converter must take place. The frequency converter must be able to replenish energy to the power meter or develop the braking energy in external resistance.

Figure 21 shows how the stator of the main machine is provided with a winding 54 for auxiliary voltage supply of the stator of the regulating machine with direct current via a controlled converter 56.

An example of an engine operation which would advantageously use a machine according to the invention are so-called electrical operations. According to current technology, for example, newsprint is produced with constant-speed synchronous motors that are limited to about 25 MW due to the problem of starting against weak power grids. An engine operation according to the invention could also lead to an increased production speed in existing plants. 10 20 25 30 35 40 '_. ._ s fï. _-. I ~ -f 'r. «. <~ «- _. _ WR '(c _.. V', .t .rt. .. - IN oc: nu: l - "_ '' * 1 t. _ N« ra - f - - 35 Släpringade statiska Kramer- och Scherbiusdrifter för pumps and fans could advantageously be replaced by machines according to the invention.

Wind tunnel operations are an example of high-power plants of over 100 MW that are well suited for AC machines according to the invention. These are currently designed as speed-controlled systems with synchronous machines with pronounced poles and full-joint current regulators for full power.

During operation, the stator winding control machine can be connected to a low-power DC network or to an AC single- or three-phase network. These networks can be arranged by using the above-mentioned auxiliary power winding in the stator of the main machine. This means that the constant frequency machine has a single connection to the power supply network, saving a transformer. If external resistance is not used during the starting process, the control machine can be made with permanent magnets.

Parallel connection of power semiconductors and parallel connection of converter modules for eg 2x3 phase is preferred for operations performed with machines according to the invention. If the rotor voltage is selected in the range 1 - 15 kV, ie if the windings are designed as picking or forming winding windings, a good filling factor is obtained for the rotor grooves of the machines. Even higher rotor voltages of up to fl tens of kV, ie for machines according to WO 97/45919, may be relevant when the power semiconductors for the vs-vs converter reach such levels.

Claims (34)

10 20 30 35 40 36 PATENT REQUIREMENTS Constant frequency machine with varying / variable speed comprising at least a first and a second rotating electric machine with a common shaft and a converter co-rotating on the shaft, characterized in that the first electric machine (1), main machine, comprises a stator and a rotor and that both the stator and the rotor are provided with alternating current windings (3, 7, 20, 21, 45, 46), that the second rotating electric machine (27), control machine, comprises a stator and a rotor and that the rotor is arranged with an alternating current winding ( 29, 48), that the converter (28, 51), comprising a number of branches with valves, is connected between the rotor windings of the main machine and the control machine and that during operation it is arranged as a vs-vs converter (5 la) and that during start-up is arranged as a vs-multi-phase switch (51b) or as a vs-phase angle / voltage regulator (51c) or as a vs-short-circuit switch (51d) and that it is arranged during controlled braking and stopping s if a vs-fl phase switch (5 lb) or as a vs phase angle / voltage regulator (51c), or as a vs short-circuit switch (5 ld) and that the stator winding (7, 20, 45) of the main machine is connected to a power supply power supply. Variable / variable speed constant frequency machine according to claim 1, characterized in that, when the machine is operating as an electric generator, a constant frequency of the main machine supply voltage to the power grid is maintained at varying speeds by the vs-vs converter (51a) feeding the main machine rotor winding. 3, 21, 46) with a voltage with a frequency corresponding to the difference frequency f, between the synchronous frequency f of the electric generator, at the current speed n, and the nominal frequency fs of the lcraf meter. Variable / variable speed constant frequency machine according to claim 1, characterized in that, when the machine operates as the motor, the desired speed of the machine is obtained by the vs-vs converter (5la) supplying the rotor winding (3, 21, 46) of the main machine with a voltage with a frequency _ corresponding to the difference frequency f., between the frequency f of the supply power network, and the synchronous frequency f of the machine, at the desired speed n ,. 20 25 30 35 40 _ ._ - (, 1 ::, u, tm, ._. 5-í, - 8¶-8§ °, _, .- «<< ---« o (_ i . t .. I m »_ .. -.- f fl- 4 '"' ffei - f '' A variable frequency machine with variable / variable speed according to claim 1, characterized in that the conversion ratio between stator winding and rotor winding is adapted to the ratio between the voltage of the mains and the maximum permissible voltage of the converter with a valve in each of the vs-vs converter branches. A constant frequency machine with varying / variable speed according to claim 1, characterized in that the stator winding (7, 20, 45) of the main machine is made of at least one cable. A variable frequency machine with varying / variable speed according to claims 1 and 5, characterized in that when the stator winding (7, 20, 45) of the main machine is made of at least one cable, the cable (s) are of the high voltage type. Variable / variable speed constant frequency machine according to claim 1, characterized in that the stator winding (7, 20, 45) of the main machine is directly connected to the alternating voltage network. A variable frequency machine with varying / variable speed according to claim 1, characterized in that the stator winding (7, 20, 45) of the main machine is connected to the alternating current network via a transformer (8). ' Variable / variable speed constant frequency machine according to claim 1, characterized in that the stator winding (7, 20, 45) of the main machine is designed as a 3-phase winding, 2-phase winding, a 2 x 3-phase winding 'or of any number phase windings. A variable frequency machine with varying / variable speed according to claim 1, characterized in that the stator of the main machine, in addition to the stator winding (7, 20, 45) which is connected to the alternating voltage network, is arranged with an auxiliary winding (41) for generating alternating voltage assist. '_ i 11. ll. A variable frequency machine with varying / variable speed according to claim 1, characterized in that the rotor winding (3, 21, 46) of the main machine is designed as a ß-phase winding, 2-phase winding, a 2 x 3-phase winding or of any number of phase windings. “- Variable / variable speed constant frequency machine according to claim 1, characterized in that the rotor winding of the control machine (3, 10 15 20 25 30 35 40 74 f. F; z t. 38 21, 46) is designed as a 3-phase winding, 2-phase winding, a 2 x 3-phase winding or of any number of phase windings. A variable frequency machine with varying / variable speed according to claim 1, characterized in that the stator of the control machine is designed with a direct current winding (30, 49). Variable / variable speed constant frequency machine according to claim 1, characterized in that the stator winding (30, 49) of the control machine is designed as an AC winding for 3-phase, 2-phase winding, a 2 x 3-phase winding or of any number of phase windings. . Variable / variable speed constant frequency machine according to claim 1, characterized in that the vs-vs converter (28, 51) is arranged to operate with varying both input and output frequencies. A variable frequency machine with varying / variable speed according to claim 1, characterized in that the vs-vs converter (28, 51) is arranged to operate with varying ratio between its input and output frequencies. _ A variable frequency machine with variable / variable speed according to claim 1, characterized in that the vs-vs converter (28, 51) is self-commutated. Variable / variable speed constant frequency machine according to claim 1, characterized in that the vs-vs converter (28, 51) is machine commutated. Variable / variable speed constant frequency machine according to claim 1, characterized in that the vs-vs converter (28, 51) is commutated by the control machine. A variable frequency machine with variable / variable speed according to claim 1, characterized in that the vs-vs converter (28, 51) is designed as a matrix converter (47). Variable / variable speed constant frequency machine according to claim 1, characterized in that the vs-vs converter (28, 51) is designed as a direct converter with antiparallel-connected thyristor bridges (50). Variable / variable speed constant frequency machine according to claim 1, characterized in that series capacitors are connected between the vs-vs converter (28, 47, 50, 51) and the rotor windings (29, 48) of the control machine. Variable / variable speed constant frequency machine according to claim 1, characterized in that shunt capacitors are connected between the vs-vs converter (28, 47, 50, 51) and the rotor windings (29, 48) of the control machine. A variable frequency machine with varying / variable speed according to claims 1, 21 and 22, characterized in that the capacitors are connected in series and / or parallel to the rotor windings (29, 48) of the control machine. . Variable / variable speed constant frequency machine according to claim 1, characterized in that the vs-vs converter (28, 51) is designed with a DC-DC intermediate. Variable / variable speed constant frequency machine according to claim 1, characterized in that the control machine during controlled start / braking / stop is arranged as a starting / braking motor whose stator winding (49) is connected to an external frequency changer (53) and whose rotor winding (48) is short-circuited by the constant frequency machine's converter connected as a vs short-circuit switch (51d). Variable / variable speed constant frequency machine according to claim 1, characterized in that at start / stop the main machine's stator winding is connected to the power meter, the main machine's rotor winding is connected to the control machine's rotor winding via the converter arranged as a reversing regulator ) is connected to external adjustable resistors. Variable / variable speed constant frequency machine according to claim 1, characterized in that during controlled start / braking / stopping the stator winding of the main machine is connected to the power grid, the rotor winding of the main machine is connected to the rotor winding of the control machine 10 20 25 30 35 40 40 via the converter arranged as vs-phase angle / bias regulator (51c) and the stator winding (49) of the control machine is connected to external fixed resistors A method of using a co-rotating converter (28, 51) arranged between the rotor windings (3, 29) of a main machine (1) and a control machine (27) of a constant frequency machine whose main machine is provided with a stator winding connected to a power grid according to claim 1. , which method is characterized as during operation, the converter is controlled as a vs-vs converter (51a) and at start-up the converter is connected as a vs-phase phase switch (51b) or as a vs-phase angle / voltage regulator (51c) or as a vs-short-circuit switch (51d) and in the case of controlled braking and stopping, the inverter is connected as a vs »fl phase switch (51b) or as a vs phase angle / voltage regulator (51c) or as a vs short-circuit switch. Method using the co-rotating converter according to claim 29, when the constant frequency machine is used as an electric generator during operation, characterized in that the vs-vs converter is arranged to supply the rotor winding (3, 21, 46) of the main machine with a voltage with a frequency which corresponds to the difference frequency between the synchronous frequency of the electric generator at the current speed and the nominal frequency of the power meter. Method of using the co-rotating converter according to claim 29, when the constant frequency machine is used as a motor during operation, characterized in that the vs-vs converter (51a) is arranged to supply the rotor winding (3, 21, 46) of the main machine with a voltage of one frequency corresponding to the difference frequency between the frequency of the power supply network and the synchronous frequency of the machine at the desired speed. A method of using the co-rotating converter according to claim 29 at start and stop, characterized in that the reverse phase coupler (51b) is arranged for direct coupling of the rotor windings of the main machine and the control machine. 20 25 30 35 41 33. A method of using the co-rotating current generator according to claim 29 for starting and controlled braking and stopping, characterized in that the vs-phase angle / voltage regulator (5lc) is arranged to control the rotor losses of the main machine via the control machine to external resistance. IN Method when using the co-rotating inverter according to claim 29 at start, brake and / or stop, characterized in that the short-circuit coupler (5 ld) is arranged to short-circuit the rotor windings of the control machine.