WO2000067363A1 - Machine a frequence constante a regime variant/variable - Google Patents

Machine a frequence constante a regime variant/variable Download PDF

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Publication number
WO2000067363A1
WO2000067363A1 PCT/SE2000/000724 SE0000724W WO0067363A1 WO 2000067363 A1 WO2000067363 A1 WO 2000067363A1 SE 0000724 W SE0000724 W SE 0000724W WO 0067363 A1 WO0067363 A1 WO 0067363A1
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WO
WIPO (PCT)
Prior art keywords
machine
converter
frequency
winding
constant
Prior art date
Application number
PCT/SE2000/000724
Other languages
English (en)
Inventor
Lars Gertmar
Original Assignee
Abb Ab
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Abb Ab filed Critical Abb Ab
Priority to CA002367389A priority Critical patent/CA2367389A1/fr
Priority to EP00928031A priority patent/EP1192701A1/fr
Priority to AU46325/00A priority patent/AU4632500A/en
Priority to EA200100962A priority patent/EA200100962A1/ru
Publication of WO2000067363A1 publication Critical patent/WO2000067363A1/fr

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Classifications

    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04B—TRANSMISSION
    • H04B5/00—Near-field transmission systems, e.g. inductive or capacitive transmission systems
    • H04B5/20—Near-field transmission systems, e.g. inductive or capacitive transmission systems characterised by the transmission technique; characterised by the transmission medium
    • H04B5/24—Inductive coupling
    • H04B5/26—Inductive coupling using coils
    • H04B5/266—One coil at each side, e.g. with primary and secondary coils
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02H—EMERGENCY PROTECTIVE CIRCUIT ARRANGEMENTS
    • H02H1/00—Details of emergency protective circuit arrangements
    • H02H1/0061—Details of emergency protective circuit arrangements concerning transmission of signals
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02K—DYNAMO-ELECTRIC MACHINES
    • H02K19/00—Synchronous motors or generators
    • H02K19/16—Synchronous generators
    • H02K19/26—Synchronous generators characterised by the arrangement of exciting windings
    • H02K19/28—Synchronous generators characterised by the arrangement of exciting windings for self-excitation
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02K—DYNAMO-ELECTRIC MACHINES
    • H02K19/00—Synchronous motors or generators
    • H02K19/16—Synchronous generators
    • H02K19/36—Structural association of synchronous generators with auxiliary electric devices influencing the characteristic of the generator or controlling the generator, e.g. with impedances or switches
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02P—CONTROL OR REGULATION OF ELECTRIC MOTORS, ELECTRIC GENERATORS OR DYNAMO-ELECTRIC CONVERTERS; CONTROLLING TRANSFORMERS, REACTORS OR CHOKE COILS
    • H02P9/00—Arrangements for controlling electric generators for the purpose of obtaining a desired output
    • H02P9/14—Arrangements for controlling electric generators for the purpose of obtaining a desired output by variation of field
    • H02P9/26—Arrangements for controlling electric generators for the purpose of obtaining a desired output by variation of field using discharge tubes or semiconductor devices
    • H02P9/30—Arrangements for controlling electric generators for the purpose of obtaining a desired output by variation of field using discharge tubes or semiconductor devices using semiconductor devices

Definitions

  • the present invention relates to an electric rotating alternating current (ac) machine, which in its basic design comprises a main machine and a regulating machine with a common mechanical shaft and a converter which rotates with the shaft and which permits brushless control of the machine.
  • the main machine is provided with a stator winding connected to a distribution or transmission power network for medium or high voltage, that is, for 1 kV and up to higher voltages .
  • the invention comprises a method when using the converter rotating with the shaft.
  • the machine may be used for conversion of mechanical power into electric power and for conversion of electric power into mechanical power, respectively. This means that the machine may function both as a generator and as a motor.
  • both the active and the reactive power which is associated with the actual operation, may be controlled.
  • the frequency of the voltage generated by the stator winding may be maintained constantly equal to the mains frequency at varying speed of the machine .
  • stator winding is connected to a power network. Operation with varying speed is controlled in a brushless manner by way of the regulating machine and the converter rotating with the shaft.
  • the invention has its primary field of application at large machine powers .
  • typical applications lie within the range of 3- 300 MW.
  • Motor drives of up to 100 MW and higher may be manufactured.
  • Machine powers both below and above the power ranges mentioned may be advantageously used.
  • the machine may be used in connection with hydroelectric machines, pump power plants, wind power plants, gas and steam turbines and as reactive-power compensator, power flow controller and transmission link in connection with power networks, as well as drive source for various motor drives .
  • the described embodiments of the invention and the description of the background art show so-called radial flow machines.
  • the machine may also wholly or partly be designed with one or more axial flow machines.
  • ac machines may be used both for generator operation and motor operation, but the optimal embodi- ments differ somewhat.
  • background art which is specific to both operating modes .
  • the cask of the machine is to generate electric power.
  • the elec- trie generator is driven by a drive means, whereby mechanical power is transformed into electric power . Since generation of electric power is normally associated with power networks, specific requirements are made for maintaining both voltage and frequency constant as well as for controlling both active and reactive power. The following description of the background art, as far as generator operation is concerned, will consequently to a large extent deal with how to achieve the desired performance relating to these parameters .
  • Motor drives primarily relate to control of torque and speed of an output shaft. However, in the same way as generation, motor drives are also associated with control of both active and reactive power.
  • a significant problem area as regards motor drives with ac machines is their start, that is, the start-up from zero speed to the relevant control range around sync ron- ous speed.
  • the description of the background art will also comprise a description of the existing start-up methods to be able to prove the improved start-up methods which are available when using ac machines according to the invention.
  • the invention will comprise a converter.
  • the description of the background art both as regards generator drives and motor drives will therefore substantially refer to embodiments where converters are included. From an electrical point of view, the converters in question will be described with the aid of accepted basic symbols according to Figure 1, which clearly describe their function, that is, according to
  • Figure Id which describes conversion from one dc voltage to another dc voltage.
  • ac-to-ac converters which will be used for carrying out the invention are referred to, in accordance with English terminology, as "ac-to-ac bidirectional conver- ters” and are explained in Webster's Electrical Engineering Handbook, Wiley 1999, under the sections AC-AC POWER CONVERTERS, written by Rik W. De Doncker, Aachen University of Technology.
  • the concept ac-to-ac converter means in this connection conversion of frequency and/or ampli- tude .
  • Converter connections for large powers are currently designed mostly with silicon-based thyristors . These connections often require large reactive powers because the currents of the ac network experience a considerable phase shift relative to the voltages thereof . This implies that the dimensioning of machines for converter- based systems and of converters must take into consideration reactive power flows, that is, reactive losses in the reactances of the machines and of ac networks as well as the need of power factor correction, thus not only the purely active power flows with more or less negligible active losses .
  • converters which will be used in connections relating to electric machines are normally constructed as units which are placed adjacent to the machine or fixedly mounted on the stator of the machine.
  • converters fixedly on the rotating parts, that is, in or on the rotating part, for example as parts of a rotating brushless system for dc excitation of synchronous machines according to the below.
  • converter-controlled rotor resistors are also used.
  • One converter connection which is very important in the above-mentioned context is a connection according to Figure lc, that is, a connection which relates to frequency or ac-to-ac conversion.
  • the mode of operation of an ac- to-ac converter may be achieved in several different ways.
  • One fundamental way is for the conversion to be performed by means of ac-dc-ac conversion, that is, with an intermediate dc link.
  • Another way is for the conversion to be achieved by means of ac-to-ac conversion which may take place in various embodiments. Examples of such are conversion by means of so-called cycloconverters with line- commutated double converters or with so-called matrix converters with self-commutated bidirectional power semiconductors .
  • n (2/p) • f_ ⁇ 60 (1)
  • the starting-point is an electricity-generating unit in the form of an electric generator and a drive means, mechanically connected thereto, in the form of a turbine, a drive motor of some kind, or the like.
  • a drive means mechanically connected thereto, in the form of a turbine, a drive motor of some kind, or the like.
  • the voltage of the electric generator possibly via a transformer, should be adapted to the voltage of the power network and that the frequency of the voltage should correspond to the frequency of the power network.
  • ABB pamphlet “Brushless exciter, SEGEN/HM 8-001. It is clear from the pamphlet that the exciter is an ac machine, the stator of which is provided with salient poles and the rotor of which has a three-phase ac winding for feeding the above-mentioned converter, preferably a six-pulse converter bridge.
  • the direct voltage, dc, of the converter is connected to the field winding of the electric generator.
  • the voltage control of the electric generator takes place by influencing the magnetization of the exciter via its stator winding
  • FIG 2 shows, in principle, how a brushless exciter is used in conventional electric generators, that is, with voltages up to 25 kV.
  • the figure shows a vertical-shaft electric generator 1 which, on the common shaft 2, is arranged with the rotor of the electric generator with a winding 3, the rotating ac winding 4 of the exciter, a converter 5 rotating with the shaft, and a drive means in the form of a turbine 6.
  • the stator 7 of the electric generator is connected to a high-voltage network via a step-up transformer 8.
  • Figure 2 also shows the stationary field winding 9 of the exciter.
  • Figure 3 shows the corresponding embodiment of the magnetization system in which the electric generator is designed as a high-voltage generator according to WO 97/45919.
  • FIG. 4 shows the corresponding embodiment of the magnetization system where the electric generator according to WO 976/45907 is designed as a 2x3-phase high-voltage generator for supplying an HVDC installation 10 with a 12-pulse connection.
  • the reference numerals are otherwise the same as in Figure 2.
  • a special embodiment of dc excitation of an electric machine rotating at constant speed is described in PCT/EP98/007744, for "Power flow control" in a trans- mission line.
  • the stator windings of the electric machine are here connected in series with the conductor of the transmission line without a connected neutral point.
  • the rotor of the electric machine is provided with two/three dc rotor windings, displaced 90/120 electrical degrees, for control of amplitude and phase of the voltage of the electric machine.
  • Supply of the rotor windings occurs via a magnetizing exciter rotating with the shaft and a converter/ac-to-dc converter for each one of the rotor windings .
  • the working point of the electric generator shall lie within a so-called A-zone which (largely) is limited by +/- 2% as far as frequency is concerned and +/- 5% as far as voltage is concerned.
  • the working point is allowed to lie within a so-called B-zone which (largely) is limited by +3 and -5% as far as frequency is concerned and +/- 8% as far as voltage is concerned.
  • the embodiments which have been used, according to the state of the art, are, however, substantially based on another principle known for such machines within electrical engineering (see, e.g., the article in Hitachi Review mentioned below) .
  • the principle will be exemplified here by means of an example of numerals based on an electric generator which is to generate a voltage of the frequency 50 Hz.
  • a typical hydroelectric plant is dimensioned for a basic speed of 375 r/min and consequently has 16 poles according to equation (1) . If the unit for certain reasons is driven by the turbine to rotate at 360 r/min, the synchronous frequency of the electric generator, upon dc excitation of the rotor poles, according to equation (1), would generate a voltage of the frequency 48 Hz .
  • equation (1) is converted into
  • n r (2/p) • (f B + f c ) ⁇ 60 (2)
  • f c is the difference frequency in question.
  • the task of a system for maintaining the frequency of the electric generator constant is thus to ensure that, independently of the actual speed of the drive means, the rotor winding is supplied with a voltage with the actual difference frequency, both as regards subsynchronous and supersyn- chronous 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 of the same.
  • the rotating converter comprises a rotor winding 12 and a stator winding 13 of which the rotor winding or the stator winding is connected to the hydroturbine unit and the other, via a transformer 8, to the high-voltage power network " Otherwise, the description discloses that the hydroelectric generator 1 comprises a shaft 2 which is arranged with the rotor of the hydroelectric generator with a winding 3 and the rotating ac winding 4 of an exciter. It is not clear from the figures or the text in the patent whether the "exci- ter power supply" (Fig. 1A, 62) is a converter rotating with the shaft or if the dc excitation takes place via a stationary converter and transmission via two slip rings.
  • Figure 5 describes that the magnetization takes place via a converter 5 rotating with the shaft.
  • Figure 5 also shows the stationary field winding 9 of the exciter and the stator winding 7 of the hydroelectric generator. As will be clear, this part of Figure 5 is identical with Figure 2.
  • the description shows that, in accordance with Figure 5, the stator power of the hydroelectric generator is transmitted via slip rings 14 on the rotating converter 11 to the rotor winding 12 thereof.
  • the voltage induced in the stator winding 13 of the converter is connected via a transformer 8 to the power network.
  • the task of the converter 11 is to provide the system with the difference frequency which is necessary for the system to be able to deliver a voltage of the proper frequency to the power network at varying speed of the hydroelectric machine. In practice, this implies that, if the hydroelectric machine rotates with its synchronous speed, the converter will be stationary, that is, operate as a stationary transformer.
  • the rotor of the converter will thus need a drive source M/G 15 in the form of a motor or a generator with an ac- to-ac converter 16. It may thus be determined that the converter 11 must be dimensioned for largely the same power as the hydroelectric generator and that the slip rings must be able to transmit the full power.
  • the converter 11 rotates with the low difference frequency, which implies that the converter must have forced cooling with a large power loss .
  • the voltage control of a hydroelectric generator 1 accor- ding to the US patent document takes place via the above- mentioned dc excitation.
  • the rotating converter 11 has in its rotor winding 12 and in its stator winding 13 leakage reactances which consume reactive power and cause voltage drops. This may be compensated for with increased dc excitation in the rotor winding 3 of the generator or may, according to the application EP 0749190 A2 , associated with the US patent, be compensated for by series capacitors . From the EP application it is also clear 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 . A significant problem with such machines is consequently to manufacture, utilize and maintain slip rings for these voltages and currents .
  • ABB Review 3/1996, pp 33 - 38 discloses an installation where "ABB Varspeed generator boosts efficiency and ope- rating flexibility of hydropower plant". The optimization takes place by allowing the turbine and the electric generator to run at variable speed. To still be able to connect the electric generator to a power network with a given and substantially fixed frequency, the frequency of the electric generator is adapted to the mains frequency with the aid of a so-called s bsynchronous/supersyn- chronous converter cascade. To be able to compare this generator drive more easily with the other embodiments described, the relevant part of Figure 4 in the 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 above-mentioned patent document.
  • the electric generator 1 comprises a shaft 2 which is arranged with the rotor of the hydroelectric generator with the winding 3.
  • Figure 6 also shows the stator winding 7 of the electric generator.
  • the frequency adap- tation to the actual mains frequency takes place with the aid of the subsynchronous/supersynchronous converter cascade 17 (CC) , which in actual fact is a so-called cycloconverter/ frequency converter.
  • the feeding to the network side thereof takes place via a transformer 18 (TR) and the actual difference frequency is fed into the rotor winding 3 of the electric generator via slip rings 19.
  • TR transformer 18
  • the actual difference frequency is fed into the rotor winding 3 of the electric generator via slip rings 19.
  • the voltage generated with the correct frequency is then fed via a transformer 8 to the power network.
  • Such a frequency adaptation of an electric generator, which is driven by a variable speed is a so- called Static Scherbius drive (see below under the description of the background art as regards motor drives ) .
  • a frequency control system is required.
  • the frequency control system is to ensure that the rotor of the converter rotates at the correct speed with the aid of a control signal 16a to the control device of M/G, and in the example shown in Figure 6 the frequency control system shall provide the correct control signal 17a to the ac-to-ac converter 17.
  • the frequency control systems are outside the scope of this invention and thus will not be described in more detail.
  • a voltage control with respect to amplitude and phase angle is also required in addition to some form of frequency control.
  • the voltage control systems are outside the scope of this invention.
  • SU 1746474 Al describes an "Asynchronised Synchronous Machine having Reversive Excitation System” .
  • This is an electric machine with a conventional three-phase stator winding connected to a power network.
  • the rotor is provided with galvanically separated phase windings. Each one of these is connected to a respective double converter rotating with the shaft.
  • These converters are desig- ned with thyristors and are supplied from a magnetizing exciter rotating with the shaft.
  • the converters are machine-commutated from the magnetizing exciter and are arranged such that they may provide the respective rotor winding with alternating voltage with a frequency corresponding to the slip frequency of the machine. It is obvious that there are problems when changing current direction in the rotor windings .
  • the OPTI-SLIP® plant is arranged with an ac-dc-dc converter rotating with the shaft and a fixed rotor resistor rotating with the shaft, directly connected to the rotor winding.
  • the ac-to-dc converter is designed with a diode rectifier, which in turn is short-circuited by a dc-to-dc converter.
  • the speed control of the wind-power plant takes place via an internal rotor-current control.
  • the loss power associated with the control is thus developed in the rotor resistor rotating with the shaft and is then emitted into the surrounding air. It is clear from the conference article that the speed may be up to 4% above the synchronous speed, resulting in power losses of the same percentage as the losses in the rotor circuit.
  • Variable-speed-controlled motor drives have existed for about 100 years. The very first ones were so-called Ward- Leonard drives, that is, dc motor drives. Somewhat later, various motor drives based on ac machines emerged. These motor drives are often named after their inventors
  • Kramer, Scherbius , Schrage, et al Characteristic of these machines is that they are provided with a wound rotor as well as brushes and slip rings or a commutator. Typical is also that they are arranged to return electric power from the rotating parts to stationary parts of the installation as, for example, rotor resistors, or that they are controlled with machines as actuators .
  • a static Kramer drive is often referred to as a sub- synchronous converter cascade and has a connection, the principle of which is shown in Figure 7.
  • the stator winding 20 of the horizontal-shaft motor is connected to a power network.
  • the rotor winding 21 is connected, via slip rings 22, to a rectifier 23, the voltage of which becomes proportional to the slip.
  • This voltage is connected in inverse feedback by the voltage from an inverter 25 connected to the same power network via a transformer 24.
  • the voltage of the inverter is a trigonometric function of its control angle and in this way determines the speed of the motor. In this way, in a static Kramer drive, the slip power is fed back to the network by frequency conversion in two stages via an intermediate dc link.
  • a static Kramer drive may be characterized as a current-controlled motor drive.
  • a static Scherbius drive is clear from Figure 8.
  • the stator winding 20 of the motor is connected to a power network in the same way as in Figure 7.
  • the rotor winding 21 is connected, via slip rings 22, to a cycloconverter/- frequency converter 26 connected to the power network via a transformer 24.
  • Specific for a Scherbius drive is that the speed is controlled via the rotor connection with the voltage of the cycloconverter, the amplitude, phase and frequency of which may be changed independently of each other.
  • a feedback from the motor is needed to maintain the correct frequency as well as the amplitude quotient and the phase ratio between the rotor voltage and the control voltage.
  • the frequency converter may supply the machine with a rotor current also during synchronous operation, which implies that the operation may, without extra electronics, change from subsynchronous to super- synchronous operation.
  • a Scherbius drive may brake both at subsynchronous and supersynchronous speed. It may also continuously operate during synchronous operation without the power semiconductors being overloaded. Hov/ever, the slip rings may become unsymmetrically loaded with a certain risk of overheating when the operation is synchronous.
  • A. static Scherbius drive may be characterized as a frequency- and voltage-controlled motor drive.
  • Hitachi Review, Vol. 44 (1995), No. 1, pp 55 - 62 describes an "400-MW Adjustable-Speed Pumped-Storage Hydraulic Power Plant” based on the Scherbius principle, where the vertical-shaft speed-controlled ac machine is used as a pump motor at night and as electric generator in the daytime. Apart from the direction of mounting of the shaft, the fundamental design, connection and functional description of the ac machine are thus the same as for Figures 6 and 8.
  • interesting numbers in this context are that, in generator operation, the rated power is 395 MVA in a speed range of 330 - 354 r/min and, in motor operation, the rated power is 380 MW in a speed control range of 330 - 390 r/min.
  • the power of the necessary cycloconverter for these control ranges is 72 MVA, that is, it is between 18 and 22% of the respective rated powers .
  • power circulates inter- nally both in the stator circuit, the rotor circuit and the air gap and via the external transformer and the ac- to-ac converter.
  • the circulating power may be both active and reactive.
  • the reactive power is consumed internally in the transformer, in the converter as well as in the rotor and stator of the ac machine.
  • This increases the rated nominal power of the electromagnetic circuit, that is, the dimensioning product of rated voltage during no- load operation and rated current at full load. At the same time, this also implies that the rated nominal power of the converters is greater than what is needed because of the circulating reactive power .
  • the ac motor drives at present have a practical upper limit of about 25 MW. This is substantially due to the problems which arise in connection with starting and accelerating the motor drives on relatively weak power networks . If a synchronous machine were to be started with a direct start, that is, with direct connection into the power network without any attempts to reduce the rotor currents, the starting current could amount to 3 - 6 times the rated current and the starting losses would substantially be developed in the rotating parts where, during the starting/acceleration process, they would be stored adiabatically . In order for a start to take place in a more controlled way, different methods are employed, such as series/parallel connection of the stator windings, with the aid of a starting transformer or with a series reactor or resistor. Start of slip-ring ac machines may take place with full stator voltage with a rotor resistance R s which is connected to the rotor winding via the slip rings and which is successively reduced when the machine starts. Such a starting device is shown in Figure 9.
  • Braking or deceleration of ac machines from the control range around synchronous speed to a standstill is performed in a manner well-known to the person skilled in the art.
  • Braking is a transient phenomenon and in the same way as starting it 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 occurs by changing two phases in the ac voltage connected to the stator winding.
  • the change of kinetic energy associated with the transient phenomenon causes loss energy in the rotor circuit, which is therefore classically designed with slip rings and external rotor resistors to carry away the loss energy from the interior of the ac machine in the same way as during starting.
  • the invention comprises an electric rotating ac machine, which in its basic design comprises a main machine and a regulating machine with a common mechanical shaft and a converter rotating with the shaft.
  • the invention also relates to a method when using the converter rotating with the shaft.
  • Characteristic of the main machine is that it is designed with ac windings in both stator and rotor and that it may operate both as an electric generator and as a motor.
  • the regulating machine has several functions. It is to supply the rotor winding of the main machine with control power/ frequency for the actual control range and it is also intended to function as a starting motor for the constant- frequency machine or to transmit the starting losses of the main machine to external resistors.
  • the converter also has several functions . Its main task is to function, during operation, as an ac-to-ac converter according to the previous definition. During starting, it should be able to function as an ac polyphase coupler or as an ac phase-angle/voltage regulator or as an ac short-circuit coupler for the rotor winding of the regulating machine. During controlled braking and/or stopping, the converter is to be able to function as an ac phase-angle/voltage regulator or as an ac polyphase coupler.
  • the invention also comprises a method for use of the converter rotating with the shaft in accordance with the above.
  • the summary of the invention will deal with the design of the stator winding of the main machine, which is largely common to the machine both as an electric generator and as a motor. Then follows a description of the machine when it is used as an electric generator with a variable speed and when it is used as a motor with variable speed. Thereafter, the design of the regulating machine and also, to a certain extent, the design of the ac-to-ac converter will be described in broad outline. Finally, the advantages possessed by a machine according to the invention in relation to the prior art will be described.
  • connection may also be transformerless or take place via power transformers.
  • the connection may also take place vis-a-vis converters for frequency conversion, for power factor correction, for filtering of harmonics, etc.
  • 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 current-carrying conductor comprising transposed, both uninsulated and insulated, strands .
  • Around the conductor is an inner semiconductive layer which is surrounded by at least one extruded insulating layer which, in turn, is surrounded by an outer semiconductive layer.
  • this layer is divided into a number of cut-off parts. Each one of these cut-off parts is then connected to ground, whereby the outer semiconductive layer will be located at ground potential or at least near ground potential.
  • Figure 10 which, as far as generated voltage is concerned, relates to a conventional electric generator, that is, an electric generator intended for voltages up to 25 kV.
  • Figure 10 has, as far as possible, the same figure symbols and reference numerals as the figures described earlier.
  • Figure 10 shows that the ac rotor winding 29 of the regulating machine is connected to the "network side" of the ac-to-ac converter and that its output is connected to the ac rotor winding 3 of the electric generator.
  • the stator winding 30 of the regulating machine may, in the same way as for previously described brushless exciters, be designed with salient poles . As will be clear from the following description, also a different embodiment may be used.
  • the main machine/the electric generator and the regulating machine are driven in the manner previously described via a turbine 6.
  • the voltage generated by the electric generator in the stator winding 7 is connected, as above, via a step-up transformer 8 to a high-voltage power network.
  • the principle of the frequency control at varying speed of the drive means is the same as previously described, that is, the ac rotor winding 3 of the electric generator is supplied with a voltage with the difference frequency which is needed to obtain the desired frequency of the generated stator voltage at the actual speed.
  • the control signal 28a of the frequency control system to the rotating ac-to-ac converter may by created in different ways which are outside the scope of this invention. The same applies to the voltage control of the system as far as amplitude and phase angle are concerned.
  • transmission of power/difference frequency is made to a conventional rotor winding which is connected to a self-commutated double converter which in a preferred embodiment consists of a matrix converter.
  • the regulating machine and the converter must be dimensioned for the actual control range both as regards torque and speed and also as regards so-called commutating overlaps because of a "weak-network" nature of the rotating windings.
  • the power of the cycloconverter relative to the rated power in the Hitachi case.
  • the regu- lating machine 27 has been drawn more proportionally correct relative to the power of the electric generator, in contrast to Figures 2, 3 etc., where the exciter shall only supply the electric generator with dc excitation power .
  • ABB Review 2/97, pp 25-33 describes one method with "Capacitor commuted convertors for HVDC systems".
  • the article describes how the commuta- ting margin is improved and how the reactive power need drops with series capacitors in ac connection, that is, between the line-commutated converter and its transformer, when the converter operates in inverter mode.
  • a corresponding technique is used in connection with the description and embodiments of the ac-to-ac converter integrated into the invention.
  • the constant-frequency machine with a variable speed may, of course, be designed for adaptation to different generating application alternatives . This is particularly true of the winding designs of both the main machine and the regulating machine and hence also of the design of the ac-to-ac converter. As examples of alternative embodiments when it comes to the stator winding of the electric generator, it may also, in addition to the embodiment shown in Figure
  • Figure 10 for a "conventional" high-voltage level as far as elec- trie generators are concerned, be designed as the electric generator described in WO 97/45919 for higher voltages according to Figure 11a which is a correspondence to Figure 3.
  • Figure lib shows an axial end view of a sector/pole pitch of a main machine according to the invention and will be described in greater detail under the description of embodiments .
  • Run-up/ starting of the constant-frequency machine to the actual control range for operation as an electric generator occurs by the turbine accelerating the main machine and the regulating machine until the machine is capable of assuming the control itself.
  • An ac machine according to the invention also has a large field of application when it comes to motor drives with varying speed.
  • a basic design for motor drives will be described starting from Figure 12.
  • FIG 12 there are a main machine/electric motor 1 with a stator winding 20 and a rotor winding 21, a regulating machine 27 arranged on a common shaft and a converter 28 in the form of an ac-to-ac converter.
  • the regulating machine is provided with a rotor winding 29 and a stator winding 30.
  • the rotor winding 29 of the regulating machine is connected to the "network side" of the ac-to-ac converter and its output is connected to the ac rotor winding 21 of the main machine/electric motor.
  • the stator machine 30 of the regulating machine 30 may be designed, in the same way as the brushless exciters mentioned above, with salient poles but also in this case other embodiments may occur.
  • the electric motor and the regulating machine jointly drive the mechanical load (not shown) .
  • the principle of varying the speed of motor drives during ac supply with a "constant" mains frequency is the same as has been described previously for electric generators, that is, that according to Figure 12 the ac rotor winding 21 of the main machine is supplied with a voltage with the difference frequency needed for the m.m.f. and flux waves created by the currents in the stator winding 20 and the rotor winding 29 to rotate synchronously in the air gap of the electric motor 1.
  • the control signal 28a of the speed/ frequency control system may be created in different ways. It depends on the requirements for dynamics, power factor, the level of the mains voltage relative to its nominal, etc.
  • the current in the rotor winding 21 of the electric motor will have the frequency zero during synchronous operation, that is, again there will be a special case with direct current in the ac rotor winding of the main machine.
  • the rotor winding of the regulating machine is to be an ac winding and that the stator winding may be designed with salient poles but that other embodiments may also occur, depending on different applications.
  • the part of the description that follows next will describe alternative embodiments .
  • the regulating machine creates a local ac network to which only the ac-to-ac converter is connected.
  • the number of poles thereof may thus be chosen relatively freely.
  • the regulating machine is preferably designed with more poles than the main machine.
  • the design with salient poles may also be carried out in different ways.
  • the preferred embodiment consists of "salient poles" with a dc winding. This creates a stationary air-gap flow in the regulating machine which permits a control possibility which is attractive from the installation engineering point of view by varying the magnitude of the air-gap flow via the value of the direct current.
  • the design with salient poles in the stator of the regulating machine also comprises the air-gap flow being created by permanent magnets, which, however, implies a largely constant air-gap flow.
  • the design with salient poles of the stator of the regulating machine is primarily of interest when the invention is to be used with different generator drives.
  • the stator winding of the regulating machine may also be designed as an ac winding, whereby a rotating air-gap flow is created in the regulating machine.
  • ac winding primarily permits supply of excitation output during operation, combined, however, with certain input/output of shaft power. This may be eliminated by supplying direct current into part of, or by switching of, the ac winding.
  • Another considerable advantage of an ac winding in the stator is that the starting conditions are significantly improved when using the machine according to the invention as a motor.
  • the ac-to-ac converters which are used, according to prior art, in connection with speed control via varying supply frequency have a constant input frequency determined by the power supply network.
  • a machine according to the invention places higher demands on the ac-to-ac converter. This is due to the fact that the input voltage/input frequency of the ac-to-ac converter, which is generated by the rotor winding of the regulating machine, varies and is, for a given machine design and power supply network, dependent on and directly proportional to the variable/varying speed of the shaft.
  • the output voltage/output frequency of the ac- to-ac converter to the rotor winding of the main machine shall be proportional to the speed difference between the synchronous and actual speeds of the main machine. This implies that the ratio of the input frequency of the ac-to-ac converter to the output frequency thereof will vary.
  • the ac-to-ac converter may be designed as a matrix converter or as a cycloconverter, that is, a voltage-source direct converter with anti- parallel-connected thyristor bridges.
  • the ac-to-ac converter may also be designed with an intermediate dc voltage link or an intermediate dc link. It shall be dimensioned so as to withstand the greatest open-circuit vol- tage occurring and the greatest possible load current in the rotor windings .
  • An ac machine according to the invention may be used, both as motor and as generator, for generating reactive power to the power network or at least they do not withdraw any reactive power from the machine.
  • Power electronic converters reduce the losses and physical dimension of the main circuits.
  • the rotor windings of both the main machine and the regulating machine may be designed with lower and hence less expensive voltage levels, since there are no longer any limiting external criteria imposed by slip rings, extended busbars and cabling.
  • the machine may be designed for one, two or more high- power connections to a power-supply network.
  • the following table shows a relative power comparison based on a given apparent rated power S n for the embodiments described.
  • the comparison relates to the sum power for the rotating machines, ROT, the sum power for the transformers included, TRAFO, the sum power for the converters included, SR, the sum of the power transmitted via slip rings, SL, and output power, UE .
  • ROT the sum power for the rotating machines
  • TRAFO the sum power for the transformers included
  • SR the sum power for the converters included
  • SR the sum of the power transmitted via slip rings
  • SL output power
  • the electric- power generator 1 and the step-up transformer 8 are designed for the same apparent rated power S n .
  • the standard concept for an installation is to use, for the brushless design, an exciter, rotating with the shaft, with a converter/ac-to-dc converter 5 for supplying the field winding 3 in the rotor.
  • the rated nominal power of the converter is to some extent dependent on the dynamic requirements of the voltage control. Typical values are, however, that it is dimensioned for 5% of the power of the electric generator.
  • the machine has no slip rings for transmission of the dc excitation to the field winding.
  • a machine according to Figure 3 This is a machine according to the previously described WO 97/45919, that is, an electric generator 1 for high voltage in which the installation does not need any step- up transformer.
  • the rated nominal power of the converter rotating with the shaft is as above, that is, about 5% of the apparent rated power.
  • the magnetization may take place without slip rings.
  • the sum converter power for the ac-to-ac converter 16 and for dc excitation of the machine 1 is estimated at about
  • the total power through the slip rings is the apparent power, transmitted from machine 1 to machine 11, which is estimated at about 1.15 • S n , starting from a short- circuit reactance of machine 11 of 0.15 pu .
  • the series capacitors mentioned in EP 0749190 will also have the value 0.15 pu . As previously described, very high demands are placed on the power-transmission capacity of the slip rings .
  • this is a system based on the Scherbius cascade, where the rotating electric machine/electric generator 1 is assumed to be designed with slip rings 19 to the cascade.
  • the ac-to-ac converter 17, that is, the converter in the cascade, is dimensioned for the actual control range and for the reactive power it consumes.
  • the installed rated power for the converter may thus be estimated at about 0.4 • S r , which also corresponds to the total power through the slip rings.
  • the apparent rated power of the rotating machine will con- sequently be about 1.3 ⁇ S n and the total installed rated power for the transformers will be about 1.4 • S n .
  • the machine comprises a first electric machine 1 called main machine and a second electric machine 27 called regulating machine with a common mechanical shaft 2 and a converter/ac-to-ac con- verter 28 rotating with the shaft.
  • the main machine 1 may be designed with high voltage "conventional" to electric generators, that is, up to 25 kV and a step-up transformer 8 or it may, according to Figure 11a, be designed with a high-voltage winding, in which case the step-up transformer is eliminated.
  • the rated nominal power for the ac-to-ac converter for the same control range as for the machine according to Figure 6 will be smaller, approximately 0.3 • S n .
  • the rated power of the regulating machine is consequently also 0.3 • S n , and the total apparent rated power of the rotating machine is 1.3 • S n .
  • the rated power of the transformer 8 in Figure 10 is 1.0 • S r .
  • Machines according to the invention thus comprise no slip rings.
  • a constant-frequency machine according to the invention in contrast to the embodiments described under the background art, has an advantage which significantly improves the starting and acceleration conditions. It has been described before that the stator winding of the regulating machine may be formed as an ac winding to allow the supply of magnetizing power for the regulating machine during operation, for example by means of an auxiliary winding in the stator of the main machine. It is also indicated in that connection that an ac winding in the stator of the regulating machine improves the starting conditions when the constant-frequency machine is used as a motor.
  • an external variable resistor may be connected, during the starting operation, to the connections of the winding to control the magnitude of the starting current and to a substantially resistive phase angle as well as to carry away losses in the main machine which are associated with the starting operation. This may be done by connecting the converter as an ac polyphase coupler. In principle, starting may also occur in such a way that the stator winding of the regulating machine is connected directly to a power network and that the rotor windings of the regulating machine and the main machine are connected together, via the converter, and that an external variable resistor is connected to the stator winding of the main machine.
  • the external resistor may be a fixed resistor. Both the main machine and the regulating machine operate in such connections as rotating transformers. A more detailed description of start-up arrangements will be given under the description of the preferred embodiments .
  • the regulating machine is dimensioned for about 30% of the power of the main machine. This permits a possibility to use the regulating machine as a starting motor during start-up, the stator winding thereof being supplied from a separate frequency converter. One condition is then that the converter rotating with the shaft is connected as an ac short-circuiting device of the rotor windings of the regulating machine. Such a connection will also be described under the description of the preferred embodiments .
  • stator and rotor windings of the main machine with the respective stator and rotor cores operate as a unit which
  • ⁇ adapts the incoming high/medium voltage to a medium/ low voltage which is optimal for the ac-to-ac converter, rotating with the shaft, as well as the regulating machine
  • ⁇ forms a "step-down" power transformer between the power supply network and the power electronics
  • ⁇ with a high-voltage cable in the stator may have a transformation ratio between the stator voltage and the rotor voltage which may amount to 100-300 times without capacitively caused amplifications of high-frequency voltages from/to the electric power system or the auxiliary-power winding arising
  • stator and rotor windings of the regulating machine with the respective stator and rotor cores operate as a unit which
  • ⁇ during transient phenomena functions as a
  • rotating transformer which conducts the losses associated therewith from the rotating parts of the machine to an external resistor.
  • Figure 1 shows block diagrams of the converters which occur in the description.
  • Figure 2 shows, in principle, how brushless exciters for dc excitation are used in connection with conventional electric generators, that is, with a voltage up to 25 kV.
  • Figure 3 shows, in principle, how brushless magnetizing exciters are used in connection with electric generators designed according to WO 97/45919, that is, with even higher voltages .
  • Figure 4 shows, in principle, how brushless magnetizing exciters are used in connection with electric generators designed according to WO 97/45907, that is, as a 2x3- phase high-voltage generator for supplying an HVDC installation .
  • FIG. 5 shows, in principle, the electric-power generating part of an installation which is clear from US
  • Figure 6 shows, in principle, the electric-power generating part of an installation which is evident from an article in which "ABB Varspeed generator boosts efficiency and operating flexibility of hydropower plant".
  • Figure 7 shows, in principle, how a static Kramer drive is designed.
  • Figure 8 shows, in principle, how a static Scherbius drive is designed.
  • Figure 9 shows how external rotor resistors are connected to the rotor winding via slip rings during a starting cycle.
  • Figure 10 shows a fundamental embodiment of a machine according to the invention, used as an electric generator for conventional high voltage, that is, for voltages up to 25 kV.
  • Figure 11a shows a fundamental embodiment of a machine according to the invention, used as an electric generator designed according to WO 97/45919, that is, with even higher voltages.
  • Figure lib 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 fundamental embodiment of a machine according to the invention, used as a motor for conventional high voltage, that is, for voltages up to 25 kV.
  • Figure 13 shows a fundamental circuit diagram for the windings of both the main machine and the regulating machine with the converter, rotating with the shaft, in the form of a matrix converter with bidirectional valves .
  • Figure 14 shows an example of alternative bidirectional controllable/extinguishable valves .
  • Figure 15 shows a fundamental circuit diagram for the windings of both the main machine and the regulating machine with the converter, rotating with the shaft, in the form of a voltage-source direct converter with anti- parallel-connected thyristor bridges.
  • Figure 16 shows a fundamental circuit diagram for the windings of both the main machine and the regulating machine as well as an indication of the various functions of the converter rotating with the shaft.
  • Figure 17 shows a fundamental circuit diagram for the windings of both the main machine and the regulating machine as well as an indication of the function of the converter, rotating with the shaft, when an external variable resistor is connected to the stator winding of the regulating machine.
  • Figure 18 shows a fundamental circuit diagram for startup with an external resistor connected to the stator winding of the regulating machine and with the converter in the form of a matrix converter utilized as an ac polyphase coupler.
  • Figure 19 shows a fundamental circuit diagram for start- up with an external resistor connected to the stator winding of the regulating machine and with the converter in the form of antiparallel-connected thyristor bridges utilized as an ac polyphase coupler.
  • Figure 20 shows a start-up arrangement of the main machine with the regulating machine as starting motor, the stator winding of which is supplied 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 regulating machine.
  • the power electronics included for the main function in the constant- frequency machine according to the invention is to be found in the rotating parts of the machine.
  • Optimum voltage levels in the windings of the rotor circuits are determined, independently of the mains voltage, primarily by the maximum permissible voltage levels of the power semiconductors and the actual connection and with and without series-connected semiconductors .
  • the stator winding of the main machine there are no such limitations . It may therefore be manufactured for direct connection to high-voltage networks. This is made possible by manufacturing/winding the stator winding with high-voltage cables, inter alia according to WO 97/45919.
  • the laminated magnetic circuit of the stator will therefore first be described based on the use of high-voltage cables in the stator winding.
  • FIG. 31 An example of an embodiment of an axial end view 31 of a sector/pole pitch of a main machine according to the invention for high voltage is clear from Figure lib.
  • Each sector/pole pitch is composed in conventional manner of sector-shaped electric sheets.
  • the stator of the machines will thus consist of a number of sectors/pole pitches which together form a laminated stator core. From a radially outermost ridge portion 32 of the core, a number of teeth 33 extend radially towards the interior of the rotor. Between the teeth there are a corresponding number of slots 34.
  • the use of the above-mentioned high-voltage cable 35 implies, among other things, that the depth of the slots for high-voltage machines is made larger than what is required according to the prior art.
  • the slot has a cross section decreasing towards the rotor since the need of cable insulation becomes lower for each winding layer towards the interior of the rotor.
  • the slot consists substantially of a circular cross section 36 around each layer of the winding with narrower waist portions 37 between the layers.
  • Such a slot cross section may, with a certain right, be referred to as a "bicycle chain slot". Since a relatively large number of layers will be needed in such a high-voltage machine and the supply of cable dimensions with regard to insulation and external semiconductors is limited, it may in practice be difficult to achieve a desirable continuous decrease of the cable insulation and the stator slot, respectively.
  • cables with three different dimensions of the cable insulation are used, arranged in three sections 38, 39 and 40, dimensioned accordingly, that is, in practice there will be a modified bicycle chain slot.
  • the figure also shows that the stator tooth may be shaped with a practically constant radial width along the whole depth of the slot.
  • the stator may be provided with a winding 41 for auxiliary-power supply, for example for the stator winding of the regulating machine.
  • the rotor Since also the rotor is provided with an ac winding, its core will consist of a design - with a number of slots somewhat differing from that of the stator - of a number of laminated sectors/pole pitches with rotor slots 42 for the rotor winding 43.
  • the rotor winding is to be supplied from the ac-to-ac converter 44 with a voltage with the actual difference frequency.
  • the voltage dimensioning of the rotor winding will then be substantially determined by the maximum permissible voltage levels in the power semiconductors included in the ac-to-ac converter. This, in turn, will be determining for the design of the rotor winding. It may thus be designed according to the prior art for conventional high/medium voltage machines or, as the one mentioned above, with a high-voltage cable, that is, according to WO 97/45919.
  • the ac-to-ac converter 44 rotating with the shaft, shown in Figure 11a is to be able to convert the relatively high frequency, 50-150 Hz, of the voltage generated in the rotor winding of the regulating machine to the difference frequency, 0-10 Hz, depending on the control range in question.
  • the converter is designed with silicon-based power semiconductors /valves with a valve in the branches of the converter, the rotor windings of the main machine and the regulating machine will be dimen- sioned for 1-3 kV.
  • the converter is designed 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 as regards voltage for the rotor windings of the main machine and the regulating machine will be access to, choice of and connection, i.e. without or with a series connection, of power semiconductors for the ac- to-ac converter.
  • Figure 13 shows a fundamental circuit diagram for the windings of both the main machine and the regulating machine with the ac-to-ac converter, rotating with the shaft, in the form of a matrix converter with bidirec- tional valves.
  • the stator winding 45 as well as the rotor winding 46 of the main machine are drawn as Y-connected three-phase windings.
  • the matrix converter 47 with the necessary shunt capacitors for creating a high-frequency low-impedance loop where the current may communicate in a simple manner between the phases in the rotor winding of the regulating machine, is connected between the ac rotor winding of the main machine and the ac rotor winding 48 of the regulating machine.
  • the above-mentioned "commutating overlaps because of a weak-network nature of the rotating windings" are eliminated by means of the matrix converter and its shunt capacitors.
  • the regulating machine may thus be designed for a lower rated nominal power.
  • the stator winding 49 of the regulating machine is shown as a three-phase winding in the embodiment shown .
  • Figures 14a, 14b and 14c indicate alternative bidirectional valves in the matrix converter. The following identification requires a certain skill in the art.
  • Figure 14a shows a bidirectional valve in the form of two GTO thyristors or two IGCTs .
  • Figure 14b shows a bidirec- tional valve with two IGBTs .
  • Figure 14c shows a bidirectional valve with one IGBT.
  • Figure 15 shows a fundamental circuit diagram for the windings of both the main machine and the regulating machine with the ac-to-ac converter, rotating with the shaft, in the form of a voltage-source direct converter with antiparallel-connected thyristor bridges.
  • both the stator winding 45 and the rotor winding 46 of the main machine are drawn as Y- connected three-phase windings.
  • the voltage-source direct converter with antiparallel-connected thyristors 50 is connected between the ac rotor winding of the main machine and the ac rotor winding 48 of the regulating machine.
  • capacitors may be series- or shunt-connected between the rotor winding of the regulating machine and the ac-to-ac converter and between the rotor winding of the main machine and the ac-to-ac converter, respectively. They may also be connected in series and/or in parallel with internal terminals inside the rotor winding of the regulating machine. Connection of capacitors in this way implies that the regulating machine may be designed for lower rated nominal power.
  • the stator winding 49 of the regulating machine is, in the embodiment shown, also here shown as a three-phase winding.
  • the scope of the invention comprises a plurality of different alternative embodiments for the windings of both the main machine and the regulating machine .
  • stator winding of the main machine a preferred embodiment is a three-phase winding as the one shown in Figures 13 and 15, that is, a conventional Y- connected winding.
  • the stator winding will be designed with a 2x3-phase winding with a 30-degree phase shift, as is clear, inter alia, from Figure 4.
  • Other winding forms for example 1-phase, 2-phase and multiphase, 2x2-phase etc., may be used for specific purposes.
  • the voltage level of the stator winding the machine may be dimensioned for conventional "machine" high voltage, that is, up to 25 kV, or it may, with high-voltage cable, be dimensioned for considerably higher voltages.
  • the stator may be provided with an extra winding for generating auxiliary power to, for example, the control of the regulating machine etc., which is shown in Figure 21.
  • the ac rotor winding of the main machine is a Y-connected three-phase winding, as those shown in Figures 13 and 15.
  • the three- phase winding may be D-connected for various reasons, the winding may be designed as a 2x3-phase winding, and other winding forms as described above may be used.
  • the Y-connected three-phase winding shown in Figures 13 and 15 is a preferred embodiment, but it may be designed D-connected or as a 1-phase winding, a 2- phase winding and as a multiphase, 2x3-phase, 2x2-phase winding, etc.
  • the ac-to-ac converter may also be supplied with single-phase alternating current from the rotor winding of the regulating machine.
  • Other winding forms may be used in connection v/ith specific applications.
  • stator winding of the regulating machine may also be designed as a Y-connected three-phase v/inding .
  • the stator of the regulating machine may be designed with salient poles for dc excitation and it may also be designed with permanent magnets. Even if the stator winding consists of a three-phase winding, it may, by means of changing-over switching, be used for dc excitation.
  • the design of the stator winding of the regulating machine is often determined by how the machine is to be started from stationary state up to the range of speed in question.
  • An ac machine according to the invention has a large number of fields of application as regards motor drives . There are processes with motor drives which, for various reasons, at present do not use speed control but which, with ac machines according to the invention, could be significantly improved.
  • the stator winding of the machine may be dimensioned for connection to power supply networks with voltage from an established low voltage up to classical high-voltage levels. Determining for the voltage which is to be used in the stator winding are largely the available mains voltage and the frequency range in question.
  • stator winding is connected preferably to a medium-voltage level of between 1 and 36 kV.
  • connection of the machine to the power supply network may preferably be dimensioned for 50 kV or higher, for example 130 kV, that is, be connected to a transmission and distribution network.
  • the converter rotating with the shaft is switchable for several different functions.
  • the function as ac-to-ac converter during operation it may also be connected for several functions in connection with starting and controlled stopping of the constant-frequency machine.
  • Figure 16 shows the preferred embodiment as regards the design of the windings during operation as well as a summary of the functions of the converter 51 both during operation, starting and stopping. Controlled braking and stopping will be described later on.
  • the functions of the converter during controlled operation and starting are as follows:
  • the function 51a of the converter corresponds to its function during operation, that is, as an ac-to-ac converter according to the definition given above.
  • the function 51b of the converter corresponds to its function during starting as an ac polyphase coupler which electronically interconnects input and output connections for interconnection of the rotor windings of the main machine and the regulating machine when an external variable resistor 52 is connected to the stator winding of the regulating machine according to Figure 17.
  • the function of the converter 51c corresponds to its functions during starting as an ac phase-angle/voltage regulator between the rotor windings of the main machine and the regulating machine when an external fixed resistor is connected to the stator winding of the regulating machine.
  • the function 51d of the converter corresponds to its function during starting as an ac short-circuit coupler of the rotor windings of the regulating machine when directly connecting the stator winding of the regulating machine to a power network according to Figure 18.
  • Figure 18 otherwise shows a fundamental circuit diagram for starting the constant-frequency machine by direct connection of the main machine to a power network.
  • Starting occurs in the manner described previously with an external three-phase controllable resistor 52 connected to the three-phase stator winding of the regulating machine.
  • the converter is now connected as an ac polyphase coupler according to 51b which connects each phase connection of the rotor winding of the main machine directly to the corresponding phase connection of the rotor winding of the regulating machine.
  • the starting losses of the main machine are now connected by way of a transformer to the regulating machine which then, via its stator winding, transfers the losses to the external resistors .
  • Figure 18 shows in detail how the converter is arranged as a polyphase coupler with a matrix converter. This function is obtained by "firing" one valve, the one marked in coarse lines, in each branch.
  • Figure 19 shows the function as an ac polyphase coupler with the converter in the form of antiparallel-connected thyristor bridges 50a and 50b.
  • the rotor winding of the main machine comprises 2x3-phase windings 46a and 46b for 6-pulse-connected thyristor bridges where each bridge needs to be provided with a pair of antiparallel-connected thyristors, marked in coarse lines, and with the corresponding rotor windings 48a and 48b of the regulating machine.
  • the regulating machine is designed for about 30% of the power of the main machine. This permits a possibility of using the regulating machine during start-up as a starting motor, the stator winding of which is supplied from a separate frequency converter 53, not rotating along with the shaft. One condition is then that the converter rotating with the shaft is connected as an ac short-circuit coupler, that is, as the function 51d, of the rotor windings of the regulating machine.
  • ac short-circuit coupler that is, as the function 51d, of the rotor windings of the regulating machine.
  • Controlled braking from the control range to a standstill is performed with the same main circuits as for starting, that is, as Figures 18 and 19.
  • the converter rotating with the shaft is utilized as
  • an ac polyphase coupler that is, as 51b above, between the rotor windings of the main machine and the regulating machine for controlling active and reactive power by direct connection of the windings with and/or without shifting the phase sequence.
  • the operations are performed by so-called counter-current braking and the power development associated with the transient phenomenon occurs in an external variable resistor 52.
  • a change of phase sequence must take place in the ac voltage connected to the stator winding of the main machine, or as
  • ⁇ an ac phase-angle/voltage regulator that is, as 51c above, whereby the external resistor is fixed and the control occurs through that proportion of the alternating current of the rotor circuit which is let through.
  • a change of phase sequence must take place in the ac voltage connected to the stator winding of the main machine, or as ⁇ an ac short-circuit coupler, that is, as 51d above, for controlled braking with the aid of a frequency converter 53 in Figure 20.
  • a change of phase sequence for connection to the stator winding of the regulating machine from the frequency converter must occur.
  • the frequency converter must be able to feed back energy to the power network or develop braking energy in an external resistor.
  • 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.
  • a controlled converter 56 for auxiliary-voltage supply of the stator of the regulating machine with direct current via a controlled converter 56.
  • a motor drive which could advantageously use a machine according to the invention are so-called refiner drives.
  • newsprint paper for example, is manufactured using constant- speed synchronous motors which are limited to about 25 MW because of the problem of starting towards weak power networks.
  • a motor drive according to the invention could, in addition, entail increased rate of production in existing plants.
  • Wind-tunnel drives are one example of high-power plants of over 100 MW which are well suited for ac machines according to the invention. These are at present designed as speed-controlled systems with synchronous machines with salient poles and current intermediate-link converters for full power.
  • the stator winding of the regulating machine may, during operation, be connected to a low-power dc network or to an ac single-phase or three-phase network. These networks may be arranged by utilizing the auxiliary-power winding, mentioned above, in the stator of the main machine. This means that the constant-frequency machine has one single connection to power supply networks, whereby one transformer is saved. If no external resistor is used during the starting operation, the regulating machine may be designed with permanent magnets.
  • Parallel connection of power semiconductors and parallel connection of converter modules, respectively, for, for example, 2x3 -phase windings are to be preferred for operations carried out by machines according to the invention.
  • the rotor voltage is selected within the range of 1 - 15 kV, that is, if the windings are designed as random-wound coils or form coils, a good fill factor is obtained for the rotor slots of the machines.
  • Still higher rotor voltages of up to several tens of kV, that is, for machines according to WO 97/45919, may come into question when the power semiconductors for the ac-to-ac converter reach such levels .

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Abstract

L'invention concerne une machine à fréquence constante présentant un régime variant/variable comprenant une machine principale (1) et une machine de régulation ayant un arbre commun (2) ainsi qu'un convertisseur (28, 51) tournant avec l'arbre et connecté entre les enroulements (3, 29) du rotor de la machine principale et la machine de régulation, et dans laquelle le convertisseur, pendant son fonctionnement, est agencé en tant que convertisseur ca-ca, et dans laquelle lors du démarrage, il est agencé en tant que coupleur polyphasé ca ou en tant que régulateur d'angle/tension de phase ou en tant que coupleur de court-circuit ca, et dans laquelle, pendant le freinage et l'arrêt régulé, il est agencé en tant que coupleur polyphasé ca ou en tant que régulateur d'angle/tension de phase ca, ou en tant que coupleur de court-circuit ca.
PCT/SE2000/000724 1999-04-30 2000-04-17 Machine a frequence constante a regime variant/variable WO2000067363A1 (fr)

Priority Applications (4)

Application Number Priority Date Filing Date Title
CA002367389A CA2367389A1 (fr) 1999-04-30 2000-04-17 Machine a frequence constante a regime variant/variable
EP00928031A EP1192701A1 (fr) 1999-04-30 2000-04-17 Machine a frequence constante a regime variant/variable
AU46325/00A AU4632500A (en) 1999-04-30 2000-04-17 A constant-frequency machine with a varying/variable speed
EA200100962A EA200100962A1 (ru) 1999-04-30 2000-04-17 Машина постоянной частоты с переменной/регулируемой скоростью вращения

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
SE9901553-9 1999-04-30
SE9901553A SE514818C2 (sv) 1999-04-30 1999-04-30 Konstantfrekvensmaskin med varierande/varierbart varvtal samt förfarande vid dylik maskin

Publications (1)

Publication Number Publication Date
WO2000067363A1 true WO2000067363A1 (fr) 2000-11-09

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PCT/SE2000/000724 WO2000067363A1 (fr) 1999-04-30 2000-04-17 Machine a frequence constante a regime variant/variable

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Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US6670721B2 (en) 2001-07-10 2003-12-30 Abb Ab System, method, rotating machine and computer program product for enhancing electric power produced by renewable facilities
WO2004055959A1 (fr) * 2002-12-17 2004-07-01 Siemens Aktiengesellschaft Machine asynchrone a double alimentation, exempte de bague collectrice
DE102004004350B3 (de) * 2004-01-29 2005-09-01 Nordex Energy Gmbh Verfahren zur Verringerung der Drehzahl eines Antriebsstranges in einer Windenergieanlage sowie Windenergieanlage mit mindestens zwei Nenndrehzahlen
US8436490B2 (en) 2005-08-30 2013-05-07 Abb Research Ltd. Wind mill power flow control with dump load and power converter

Families Citing this family (18)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE10261453B4 (de) * 2002-12-31 2010-04-15 Danfoss Drives A/S Motorsteuerung
DE102004054581B4 (de) * 2004-11-11 2007-02-08 Siemens Ag Messsystem mit rotierender Erfassungseinrichtung insbesondere für einen Motor oder einen Generator
DE102005007371A1 (de) * 2005-02-17 2006-08-24 Siemens Ag Elektrische Maschine
US8384605B2 (en) 2009-02-25 2013-02-26 Sikorsky Aircraft Corporation Wireless communication between a rotating frame of reference and a non-rotating frame of reference
KR20140096356A (ko) 2011-11-28 2014-08-05 에이비비 테크놀로지 아게 회전 전기기계
US9325229B2 (en) * 2013-03-15 2016-04-26 Hamilton Sundstrand Corporation Generator architecture with PMG exciter and main field rotating power converter
JP5941216B2 (ja) * 2013-03-18 2016-06-29 株式会社日立製作所 回転電機システム及びその制御方法
DE102013208552A1 (de) 2013-05-08 2014-11-13 Lenze Drives Gmbh Antriebssystem
WO2014181454A1 (fr) * 2013-05-10 2014-11-13 株式会社 日立製作所 Système de machine électrique rotative ou système de production d'énergie éolienne
US9813004B2 (en) * 2015-01-16 2017-11-07 Abb Schweiz Ag Systems and methods concerning exciterless synchronous machines
JP6375967B2 (ja) * 2015-01-26 2018-08-22 スズキ株式会社 回転電機
US10075106B2 (en) * 2015-04-10 2018-09-11 Hamilton Sundstrand Corporation DC synchronous machine
US10033252B2 (en) 2015-04-14 2018-07-24 Hamilton Sundstrand Corporation Sensorless control of a DC synchronous machine
RU2647882C2 (ru) * 2016-02-24 2018-03-21 Федеральное Государственное Бюджетное Образовательное Учреждение Высшего Образования "Новосибирский Государственный Технический Университет" Устройство питания асинхронного двигателя
JP2017212827A (ja) * 2016-05-26 2017-11-30 株式会社日立製作所 無線通信装置および発電システム
GB2560314B (en) * 2017-03-06 2022-03-30 Safran Electrical & Power An electrical machine
CA3027957A1 (fr) 2017-12-20 2019-06-20 Tti (Macao Commercial Offshore) Limited Generateur d'alimentation portatif dote de surveillance et controle d'alimentation
EP4239866A1 (fr) * 2022-03-02 2023-09-06 BSH Hausgeräte GmbH Machine électrique, moteur à flux axial, unité d'alimentation électrique, et appareil domestique

Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3671850A (en) * 1970-11-19 1972-06-20 Walter E Mehnert Electric generator control system with radio feedback loop
US4625160A (en) * 1984-12-17 1986-11-25 Sundstrand Corporation Variable speed constant frequency generating system
WO1997045919A2 (fr) * 1996-05-29 1997-12-04 Asea Brown Boveri Ab Machines electriques tournantes a circuit magnetique pour haute tension et leur procede de fabrication
US5742515A (en) * 1995-04-21 1998-04-21 General Electric Co. Asynchronous conversion method and apparatus for use with variable speed turbine hydroelectric generation

Family Cites Families (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4723106A (en) * 1986-08-29 1988-02-02 General Electric Company Brushless generator exciter using hybrid rectifier
DE19507760A1 (de) * 1995-03-06 1996-09-12 Siemens Ag Verfahren und Anordnung zur Übertragung eines Datenwerts zwischen einem feststehenden und einem rotierenden Kommunikationsmodul

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3671850A (en) * 1970-11-19 1972-06-20 Walter E Mehnert Electric generator control system with radio feedback loop
US4625160A (en) * 1984-12-17 1986-11-25 Sundstrand Corporation Variable speed constant frequency generating system
US5742515A (en) * 1995-04-21 1998-04-21 General Electric Co. Asynchronous conversion method and apparatus for use with variable speed turbine hydroelectric generation
WO1997045919A2 (fr) * 1996-05-29 1997-12-04 Asea Brown Boveri Ab Machines electriques tournantes a circuit magnetique pour haute tension et leur procede de fabrication

Cited By (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US6670721B2 (en) 2001-07-10 2003-12-30 Abb Ab System, method, rotating machine and computer program product for enhancing electric power produced by renewable facilities
WO2004055959A1 (fr) * 2002-12-17 2004-07-01 Siemens Aktiengesellschaft Machine asynchrone a double alimentation, exempte de bague collectrice
DE10259068A1 (de) * 2002-12-17 2004-07-15 Siemens Ag Schleifringlose doppeltgespeiste Asynchronmaschine
DE102004004350B3 (de) * 2004-01-29 2005-09-01 Nordex Energy Gmbh Verfahren zur Verringerung der Drehzahl eines Antriebsstranges in einer Windenergieanlage sowie Windenergieanlage mit mindestens zwei Nenndrehzahlen
US8436490B2 (en) 2005-08-30 2013-05-07 Abb Research Ltd. Wind mill power flow control with dump load and power converter

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SE9901553L (sv) 2000-10-31
WO2000067355A1 (fr) 2000-11-09
CA2367386A1 (fr) 2000-11-09
SE514818C2 (sv) 2001-04-30
CA2367389A1 (fr) 2000-11-09
AU4787900A (en) 2000-11-17
SE9901553D0 (sv) 1999-04-30
EA200100962A1 (ru) 2002-04-25
EP1192701A1 (fr) 2002-04-03
EP1175718A1 (fr) 2002-01-30
AU4632500A (en) 2000-11-17

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