EP1020012A1 - A rotary electric machine - Google Patents
A rotary electric machineInfo
- Publication number
- EP1020012A1 EP1020012A1 EP98945745A EP98945745A EP1020012A1 EP 1020012 A1 EP1020012 A1 EP 1020012A1 EP 98945745 A EP98945745 A EP 98945745A EP 98945745 A EP98945745 A EP 98945745A EP 1020012 A1 EP1020012 A1 EP 1020012A1
- Authority
- EP
- European Patent Office
- Prior art keywords
- machine
- layer
- excitation
- winding
- conductor
- Prior art date
- Legal status (The legal status 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 status listed.)
- Withdrawn
Links
Classifications
-
- 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
-
- 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
- H02P9/02—Details
-
- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02K—DYNAMO-ELECTRIC MACHINES
- H02K2203/00—Specific aspects not provided for in the other groups of this subclass relating to the windings
- H02K2203/15—Machines characterised by cable windings, e.g. high-voltage cables, ribbon cables
-
- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02K—DYNAMO-ELECTRIC MACHINES
- H02K3/00—Details of windings
- H02K3/32—Windings characterised by the shape, form or construction of the insulation
- H02K3/40—Windings characterised by the shape, form or construction of the insulation for high voltage, e.g. affording protection against corona discharges
Definitions
- the present invention relates to a rotary electric machine of alternating current type designed to be connected directly to a distribution or transmission network and comprising at least one electric winding.
- the invention also relates to an electric power plant comprising such an electric machine, and also to a method of exciting a rotary electric machine.
- the rotary electric machine according to the invention may be a synchronous machine, dual-fed machine, external pole machine or synchronous flow machine.
- transformers To connect machines of this type to distribution or transmission networks, in the following referred to as power networks, transformers have hitherto been used to step up the voltage to network level, i.e. to the range of 130-400 kV.
- Generators having a rated voltage of up to 36 kV are described by Paul R. Siedler "36 kV Generators Arise from Insulation Research", Electrical World, 15 October 1932, pages 524-527. These generators comprise windings of high-voltage cable in which the insulation is divided into different layers with different dielectric constants.
- the insulating material used consists of various combinations of the three components mica-foil mica, varnish and paper.
- the excitation equipment is frequently required to be able to produce a peak voltage and peak current of 1.5 to 3 times greater than equivalent magnitudes in the case of rated load excitation for the machine in question, for a duration of 10-30 seconds.
- the excitation equipment shall also be able to produce a field current equivalent to the rated load excitation current for 25% voltage on the stator terminal of the machine.
- the excitation system shall preferably be "maintenance free", i.e. an excitation system without slip rings.
- the response and transient times at network disturbances shall also be rapid, i.e. the excitation equipment shall be able to generate both positive and negative field voltage.
- the excitation system shall generally be able to produce both positive and negative field current and demands for peak voltage factors greater than 3 times the rated load excitation voltage may occur.
- Brushless exciters eliminate the problems of dirt from carbon dust from brushes and slip rings.
- brushless exciters in accordance with known technology exhibit poorer control performance than static exciters.
- the object of the present invention is thus to provide a rotary electric machine that can be connected directly to a power network and that is provided with a "maintenance free” excitation system with improved control performance, and an electric power plant comprising such an electric machine, as well as to propose a method for excitation of a rotary electric machine.
- the insulating conductor or high-voltage cable used in the present invention is flexible and is of the type described in more detail in WO 97/45919 and WO 97/45847.
- the insulated conductor or cable is described further in WO 97/45918, WO 97/45930 and WO 97/45931.
- the windings are preferably of a type corresponding to cables having solid, extruded insulation, like those cur- rently used for power distribution, such as XLPE-cables or cables with EPR- insulation.
- a cable comprises an inner conductor composed of one or more strands, an inner semi-conducting layer surrounding the conductor, a solid insulating layer surrounding this semiconducting layer and an outer semiconducting layer surrounding the insulating layer.
- Such cables are flexible, which is an important property in this context since the technology for the device according to the invention is based primarily on winding systems in which the winding is formed from cables which are bent during assembly.
- the flexibility of a XLPE-cable normally corresponds to a radius of curvature of approximately 20 cm for a cable 30 mm in diameter, and a radius of curvature of approximately 65 cm for a cable 80 mm in diameter.
- the term "flexible" is used to indicate that the winding is flexible down to a radius of curvature of the order of four times the cable diameter, preferably eight to twelve times the cable diameter.
- the winding should be constructed to retain its properties even when it is bent and when it is subjected to thermal or mechanical stress during operation. It is vital that the layers retain their adhesion to each other in this context.
- the material properties of the layers are decisive here, particularly their elasticity and relative coefficients of thermal expansion.
- the insulat- ing layer consists of cross-linked, low-density polyethylene, and the semiconducting layers consist of polyethylene with soot and metal particles mixed in.
- the insulating layer may consist, for example, of a solid thermoplastic material such as low-density polyethylene (LDPE), high-density polyethylene (HDPE), polypropylene (PP), polybutylene (PB), polymethyl pentane (PMP), cross-linked materials such as cross-linked polyethylene (XLPE), or rubber such as ethylene propylene rubber (EPR) or silicon rubber.
- LDPE low-density polyethylene
- HDPE high-density polyethylene
- PP polypropylene
- PB polybutylene
- PMP polymethyl pentane
- XLPE cross-linked polyethylene
- EPR ethylene propylene rubber
- the inner and outer semiconducting layers may be of the same basic material but with particles of conducting material such as soot or metal powder mixed in.
- the mechanical properties of these materials are affected relatively little by whether soot or metal powder is mixed in or not - at least in the proportions required to achieve the conductivity necessary according to the invention.
- the insulating layer and the semiconducting layers thus have substantially the same coefficients of thermal expansion.
- Ethylene-vinyl-acetate copolymers/nitrile rubber, butylymp polyethylene, ethylene- acrylate-copolymers and ethylene-ethyl-acrylate copolymers may also constitute suitable polymers for the semiconducting layers.
- the materials listed above have relatively good elasticity, with an E-modulus of E ⁇ 500 MPa, preferably ⁇ 200 MPa.
- the elasticity is sufficient for any minor differences between the coefficients of thermal expansion for the materials in the layers to be absorbed in the radial direction of the elasticity so that no cracks or other damage appear and so that the layers are not released from each other.
- the material in the layers is elastic, and the adhesion between the layers is at least of the same magnitude as the weakest of the materials.
- the conductivity of the two semiconducting layers is sufficient to substantially equalize the potential along each layer.
- the conductivity of the outer semiconducting layer is sufficiently large to contain the electrical field in the cable, but suf- ficiently small not to give rise to significant losses due to currents induced in the longitudinal direction of the layer.
- each of the two semiconducting layers essentially constitutes one equipo- tential surface, and the winding with these layers will substantially enclose the electrical field within it.
- the excitation system comprises two controllable antiparallel-connected current converter devices for feeding the field winding of the alternating current machine, a two-way field over-voltage protection means or discharge circuit con- nected across the field winding, and also control equipment for controlling the current converters and over-voltage protection means or discharge circuit.
- This is a simple construction requiring no galvanically separated supply sources and current-limiting reactances and no separate short-circuiting devices for extinguishing conducting thyristors.
- the excitation system is also well suited for synchronous machines such as synchronous compensators.
- the present invention thus exploits the ability offered by semiconductor technology to temporarily change the polarity in a simple manner, which facilitates rapid commutation of the field current from static current converter bridge to short-circuiting circuit and vice versa when a change of current direction is required in the field circuit of the machine.
- Figure 1 shows the insulated cable used in the machine in accordance with the invention
- Figure 2 shows a circuit diagram of the excitation system in the machine in accordance with the invention
- Figures 3a-f show the voltage and current variation upon bridge switching in the excitation system shown in Figure 2.
- Figure 1 shows a cross section through an insulated conductor 11 intended for use in the windings of the machine in accordance with the present invention.
- the insulated conductor 11 thus comprises a number of strands 35 having circular cross section and consisting of copper (Cu), for instance. These strands 35 are arranged in the middle of the insulated conductor 11.
- a first semiconducting layer 13 is arranged around the strands 35.
- An insulating layer 37 e.g. XLPE insulation, is arranged around the first semiconducting layer 13.
- a second semiconducting layer 15 is arranged around the insulating layer 37.
- the insulated conductor is flexible and retains this property throughout its service life. Said three layers are constructed so that they adhere to each other even when the insulated conductor is bent.
- the insulated conductor has a diameter within the interval 20-250 mm and a conducting area within the interval 80-3000 mm2. o
- Figure 2 shows a circuit diagram for the excitation system in the machine in accordance with the invention.
- the field winding 4 of the machine which may be stationary or rotating, is connected to two antiparallel-connected current converter bridges 1 , 2.
- a two-way over-voltage protection means comprising two antiparal- lel-connected thyristors 8, 10 with associated ignition circuits 12, 14, is also provided over the field winding 4.
- the current converter bridges 1 , 2 are supplied from a source 16 and controlled from a switching logic 18 via control pulse amplifiers 20, 22.
- a control pulse gen- erator 28 for the current converter bridges 1 , 2 in the form of thyristor bridges is also arranged to emit control pulses to the pulse amplifiers 20, 22.
- Measuring instruments 24, 26 are also arranged to measure the currents IFB1 and IFB2, respectively, from the current converter bridges 1 , 2, and transmit the measured results to the switching logic 18 for control purposes.
- Connection of the thyristors 8, 10 of the over-voltage protection means is also controlled from the switching logic 18 via the ignition circuits 12, 14.
- the over-voltage protection means is connected to a current-limiting resistor R. In the system with field breakers this resistor R serves as discharge resistor.
- bridge 1 is assumed to be conducting, which means that the current direction IF through the field winding 4 is positive, see Figures 3a and 3b.
- the control signal Ust see
- a suitable choice of current levels for generating blocking and detecting signals ensures that the time interval is brief for connecting the two-way field over-voltage protection means 8, 10, 12, 14 serving as auxiliary circuit or the two-way thyristor discharge circuit.
- extinguishable semiconductor elements can also shorten the time interval for switching between positive and negative excitation or vice versa.
- introduction of extinguishable semiconductor elements in the two- way over-voltage protection makes temporary reversal of the field voltage unnecessary in order to extinguish an activated and conducting semiconductor element.
Abstract
Description
Claims
Applications Claiming Priority (3)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
SE9703555 | 1997-09-30 | ||
SE9703555A SE512721C2 (en) | 1997-09-30 | 1997-09-30 | Rotary electric machine, machine comprising at least one rotating electric main machine and electric power plant comprising a rotating electric machine and method for magnetizing a rotating electric machine |
PCT/SE1998/001741 WO1999017432A1 (en) | 1997-09-30 | 1998-09-29 | A rotary electric machine |
Publications (1)
Publication Number | Publication Date |
---|---|
EP1020012A1 true EP1020012A1 (en) | 2000-07-19 |
Family
ID=20408451
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
EP98945745A Withdrawn EP1020012A1 (en) | 1997-09-30 | 1998-09-29 | A rotary electric machine |
Country Status (15)
Country | Link |
---|---|
EP (1) | EP1020012A1 (en) |
JP (1) | JP2001518780A (en) |
KR (1) | KR20010052083A (en) |
CN (1) | CN1272246A (en) |
AU (1) | AU736279B2 (en) |
BR (1) | BR9812569A (en) |
CA (1) | CA2305422A1 (en) |
EA (1) | EA002196B1 (en) |
IL (1) | IL134819A0 (en) |
NO (1) | NO20001318D0 (en) |
NZ (1) | NZ503658A (en) |
PL (1) | PL339569A1 (en) |
SE (1) | SE512721C2 (en) |
WO (1) | WO1999017432A1 (en) |
ZA (1) | ZA988874B (en) |
Families Citing this family (1)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
RO126983A0 (en) * | 2011-06-03 | 2011-12-30 | Bultoc Călin | Low speed electric generator |
Family Cites Families (5)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
AT340523B (en) * | 1976-04-27 | 1977-12-27 | Hitzinger & Co Dipl Ing | BRUSHLESS SYNC GENERATOR |
DE2622309C3 (en) * | 1976-05-19 | 1979-05-03 | Siemens Ag, 1000 Berlin Und 8000 Muenchen | Protective device for a brushless synchronous machine |
SU873370A1 (en) * | 1979-03-11 | 1981-10-15 | Предприятие П/Я М-5113 | Synchronous machine excitation system |
US5036165A (en) * | 1984-08-23 | 1991-07-30 | General Electric Co. | Semi-conducting layer for insulated electrical conductors |
DE3543106A1 (en) * | 1985-12-06 | 1987-06-11 | Kabelmetal Electro Gmbh | ELECTRIC CABLE FOR USE AS WINDING STRING FOR LINEAR MOTORS |
-
1997
- 1997-09-30 SE SE9703555A patent/SE512721C2/en not_active IP Right Cessation
-
1998
- 1998-09-29 AU AU92921/98A patent/AU736279B2/en not_active Ceased
- 1998-09-29 WO PCT/SE1998/001741 patent/WO1999017432A1/en not_active Application Discontinuation
- 1998-09-29 EA EA200000363A patent/EA002196B1/en not_active IP Right Cessation
- 1998-09-29 NZ NZ503658A patent/NZ503658A/en unknown
- 1998-09-29 CA CA002305422A patent/CA2305422A1/en not_active Abandoned
- 1998-09-29 EP EP98945745A patent/EP1020012A1/en not_active Withdrawn
- 1998-09-29 BR BR9812569-9A patent/BR9812569A/en not_active IP Right Cessation
- 1998-09-29 PL PL98339569A patent/PL339569A1/en unknown
- 1998-09-29 KR KR1020007003465A patent/KR20010052083A/en not_active Application Discontinuation
- 1998-09-29 IL IL13481998A patent/IL134819A0/en unknown
- 1998-09-29 JP JP2000514384A patent/JP2001518780A/en active Pending
- 1998-09-29 CN CN98809669A patent/CN1272246A/en active Pending
- 1998-09-29 ZA ZA988874A patent/ZA988874B/en unknown
-
2000
- 2000-03-14 NO NO20001318A patent/NO20001318D0/en not_active Application Discontinuation
Non-Patent Citations (1)
Title |
---|
See references of WO9917432A1 * |
Also Published As
Publication number | Publication date |
---|---|
EA002196B1 (en) | 2002-02-28 |
KR20010052083A (en) | 2001-06-25 |
WO1999017432A1 (en) | 1999-04-08 |
AU9292198A (en) | 1999-04-23 |
SE9703555D0 (en) | 1997-09-30 |
NZ503658A (en) | 2001-11-30 |
CA2305422A1 (en) | 1999-04-08 |
SE9703555L (en) | 1999-03-31 |
CN1272246A (en) | 2000-11-01 |
AU736279B2 (en) | 2001-07-26 |
IL134819A0 (en) | 2001-05-20 |
NO20001318L (en) | 2000-03-14 |
NO20001318D0 (en) | 2000-03-14 |
BR9812569A (en) | 2000-08-01 |
SE512721C2 (en) | 2000-05-02 |
EA200000363A1 (en) | 2000-12-25 |
PL339569A1 (en) | 2000-12-18 |
JP2001518780A (en) | 2001-10-16 |
ZA988874B (en) | 1999-06-04 |
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Legal Events
Date | Code | Title | Description |
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Effective date: 20031104 |