WO1997016885A1 - Systeme d'interconnexion pour la transmission de puissance entre des systemes electriques - Google Patents

Systeme d'interconnexion pour la transmission de puissance entre des systemes electriques Download PDF

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Publication number
WO1997016885A1
WO1997016885A1 PCT/US1996/015216 US9615216W WO9716885A1 WO 1997016885 A1 WO1997016885 A1 WO 1997016885A1 US 9615216 W US9615216 W US 9615216W WO 9716885 A1 WO9716885 A1 WO 9716885A1
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WO
WIPO (PCT)
Prior art keywords
rotor
control unit
electrical
electrical system
power
Prior art date
Application number
PCT/US1996/015216
Other languages
English (en)
Inventor
Mark Andrew Runkle
Einar Vaughn Larsen
Original Assignee
General Electric Company
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 General Electric Company filed Critical General Electric Company
Priority to EP96933092A priority Critical patent/EP0800717A4/fr
Priority to BR9606958A priority patent/BR9606958A/pt
Publication of WO1997016885A1 publication Critical patent/WO1997016885A1/fr

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Classifications

    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
    • H02J3/00—Circuit arrangements for ac mains or ac distribution networks
    • H02J3/34—Arrangements for transfer of electric power between networks of substantially different frequency
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01F—MAGNETS; INDUCTANCES; TRANSFORMERS; SELECTION OF MATERIALS FOR THEIR MAGNETIC PROPERTIES
    • H01F38/00—Adaptations of transformers or inductances for specific applications or functions
    • H01F38/18—Rotary transformers
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
    • H02J3/00—Circuit arrangements for ac mains or ac distribution networks
    • H02J3/18—Arrangements for adjusting, eliminating or compensating reactive power in networks
    • H02J3/1821—Arrangements for adjusting, eliminating or compensating reactive power in networks using shunt compensators
    • H02J3/1828—Arrangements for adjusting, eliminating or compensating reactive power in networks using shunt compensators with stepwise control, the possibility of switching in or out the entire compensating arrangement not being considered as stepwise control
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02K—DYNAMO-ELECTRIC MACHINES
    • H02K47/00—Dynamo-electric converters
    • H02K47/18—AC/AC converters
    • H02K47/22—Single-armature frequency converters with or without phase-number conversion
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02K—DYNAMO-ELECTRIC MACHINES
    • H02K47/00—Dynamo-electric converters
    • H02K47/18—AC/AC converters
    • H02K47/22—Single-armature frequency converters with or without phase-number conversion
    • H02K47/26—Single-armature frequency converters with or without phase-number conversion operating as under- or over-synchronously running asynchronous induction machines, e.g. cascade arrangement of asynchronous and synchronous machines
    • 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
    • H02P9/48—Arrangements for obtaining a constant output value at varying speed of the generator, e.g. on vehicle
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
    • Y02E40/00—Technologies for an efficient electrical power generation, transmission or distribution
    • Y02E40/30—Reactive power compensation

Definitions

  • This invention pertains to control of electrical power transmission and particularly to transmission of power between electrical systems
  • Some electrical transformers for example tap-changing transformers such as va ⁇ acs, merely vary voltage
  • Other transformers known as stationary phase shifting transformers, can divert power and move power through a torque angle Mere voltage-varying transformers and stationary phase shifting transformers may be adequate for interconnecting two electrical systems operating at the same elect ⁇ cal frequency, or for transmission within a utility company
  • stationary phase shifting transformers can divert power and move power through a torque angle Mere voltage-varying transformers and stationary phase shifting transformers may be adequate for interconnecting two electrical systems operating at the same elect ⁇ cal frequency, or for transmission within a utility company
  • such transformers are incapable of interfacing two electrical systems operating a differing frequency (e g, inter-utility transfers of electricity)
  • HVDC high voltage direct current
  • Fig 8 is a one-line diagram schematically illustrating a prior art HVDC interconnection system 820
  • Fig 8 shows interconnection system 820 connecting a first or supply system 822 (shown as AC Power System #1 ) and a second or receiver system 824 (shown as AC Power System #2)
  • AC Power System #1 is connected to interconnection system 820 by lines 826 for supplying, in the illustrated example, a three-phase input signal of frequency F1 (F1 being the frequency of supply system 822)
  • Interconnection system 820 is connected by lines 828 to receiver system 824, with lines 828 carrying a three-phase output signal of frequency F2 from interconnection system 820 to receiver system 824
  • HVDC interconnection system 820 of Fig 8 includes a back-to-back
  • DC link 830 situated between bus bars 832 and 834 Bus bar 832 is connected to supply lines 826 and to reactive compensation bus 842
  • Bus bar 834 is similarly connected to lines 828 and to reactive compensation bus 844.
  • Each side of back-to-back DC link 830 includes two transformers (e.g., transformers YY and Y ⁇ on the first system side; transformers YY and ⁇ Y on the second system side) and a 12 pulse converter group.
  • the 12 pulse converter group for the first side of link 830 includes two six pulse converter groups 850 and 852; the 12 pulse converter group for the second side of link 830 includes two six pulse converter groups 860 and 862.
  • each converter group includes six thyristors connected in a manner understood by the man skilled in the art.
  • Smoothing filter 864 is connected between converter groups 850 and 860.
  • Reactive power supply system 870 includes a shunt reactor 871 connected to bus 842 by switch 872, as well as a plurality of filter branches 873A, 873B, 873C connected to bus 842 by switches 874A, 874B, and 874C, respectively.
  • reactive power supply system 880 includes a shunt reactor 881 connected to bus 844 by switch 882, as well as a filter branches 883A, 883B, 883C connected to bus 844 by switches 884A, 884B, and 884C, respectively.
  • three such filter branches 873A - 873C and 883A - 883C have been illustrated, it should be understood that a greater number of filter branches may reside in each reactive power supply system 870, 880.
  • HVDC is complicated due e.g , to the need to closely coordinate harmonic filtering, controls, and reactive compensation Moreover, HVDC has performance limits when the AC power system on either side has low capacity compared to the HVDC power rating Further HVDC undesirably requires significant space, due to the large number of high-voltage switches and filter banks.
  • Prior art rotary converters utilize a two-step conversion, having both a fully-rated generator and a fully-rated motor on the same shaft
  • Rotary converters have been utilized to convert power from AC to DC or from DC to AC.
  • Such rotary converters do not convert directly from AC to AC at differing frequencies.
  • rotary converters run continuously at one predetermined speed (at hundreds or thousands of RPMs), acting as motors that actually run themselves.
  • Prior art rotary converters accordingly cannot address the problem of interconnecting two electrical systems that are random walking in their differing frequency distributions
  • An electrical interconnection system comprises a rotary transformer and a control system.
  • the control system adjusts an angular position of the rotary transformer so that measured power transferred from a first electrical system to a second electrical system matches an inputted order power.
  • the rotary transformer comprises a rotor assembly and a stator, with the control system adjusting a time integral of rotor speed over time.
  • the control system includes a first control unit and a second control unit.
  • the first control unit compares the input order power to the measured power to generate a requested angular velocity signal
  • the second control unit compares the requested angular velocity signal to a measured angular velocity signal of the rotary transformer to generate a converter drive signal, thereby controlling the angular positioning of the rotor assembly relative to the stator.
  • the rotary transformer comprises a rotor connected to the first electrical system and a stator connected to the second electrical system.
  • a torque control unit or actuator rotates the rotor in response to the drive signal generated by the control system.
  • the bandwidth of the control system is such to dampen oscillations
  • the bandwidth of the first (slow) control unit is chosen to be below the lowest natural mode of oscillation
  • the bandwidth of the second (fast) control unit is chosen to be above the highest natural mode of oscillation
  • the bandwidth of a control unit or control system refers to the speed of response of a closed-loop feedback unit or system
  • the first and second electrical systems may have a differing electrical characteristic (e g , frequency or phase)
  • the controller bi-directionally operates the rotary transformer at a variable speed for transferring power from the first electrical system to the second electrical system or vise versa
  • the torque control unit is a motor
  • the torque control unit may either directly drive the rotor, or interface with the rotor via a gear
  • the gear is a worm gear
  • the torque control unit is integrated in the rotor assembly and stator of the rotary transformer
  • the function of the torque control unit is accomplished by providing two sets of windings on both the rotor and the stator, a first set of windings on the rotor and stator having a different number of poles (e g , 2 poles) than a second set of windings on the rotor and stator (e g , 4 or more poles)
  • the embodiments in which the torque control unit is integrated in the rotor assembly and stator of the rotary transformer include a squirrel cage inductor embodiment, DC-excited rotor (synchronous) embodiment, and, a wound rotor AC embodiment
  • the interconnection system of the present system is uti zable in a substation for connecting asynchronous electrical systems such as first and second power grids having differing electrical frequencies.
  • the interconnection system of the invention not only transfers power, but can also modify power rapidly by accomplishing phase shift under load.
  • mechanical torque of the rotary transformer is controlled to achieve an ordered power transfer from stator to rotor windings.
  • the present invention contrasts with prior art techniques which controlled power transfer from rotor to stator windings for the purpose of controlling torque applied to the load (and thereby its speed).
  • both rotor and stator windings are rated for full power transfer, whereas in prior art applications the rotor winding was rated only for a small fraction of the stator winding.
  • the present invention avoids the prior art HVDC need to closely coordinate harmonic filtering, controls, and reactive compensation.
  • the present invention also advantageously provides a one-step conversion.
  • Fig. 1 is schematic view of a ⁇ electrical power interconnection system according to an embodiment of the invention.
  • Fig. 2 is a partial schematic, partial perspective view of an electrical power interconnection system according to an embodiment of the invention.
  • Fig. 3A is a side view of a ⁇ electrical power interconnection system according to an embodiment of the invention which utilizes a worm gear.
  • Fig. 3B is top view of the electrical power interconnect system of Fig. 3A.
  • Fig. 4 is a schematic view of a substation for electrical interconnecting a first electrical system and a second electrical system.
  • Fig. 5 is a graph showing torque-control requirements of the electrical power interconnection system of the present invention.
  • Fig. 6 is a graph showing a capability curve of the electrical power interconnection system of the present invention.
  • Fig. 7 is a top schematic view of an embodiment wherein a torque control unit is integrated in the rotor assembly and stator of the rotary transformer
  • Fig. 7A is a top schematic view of an embodiment wherein a torque control unit is integrated in the rotor assembly and stator of the rotary transformer in a squirrel cage inductor configuration.
  • Fig. 7B is a top schematic view of an embodiment wherein a torque control unit is integrated in the rotor assembly and stator of the rotary transformer in a DC-excited rotor (synchronous) configuration.
  • Fig. 7C is a top schematic view of an embodiment wherein a torque control unit is integrated in the rotor assembly and stator of the rotary transformer in a wound rotor AC configuration.
  • Fig. 8 is a one-line diagram schematically illustrating a prior art HVDC interconnection system.
  • Fig. 9 is a phasor diagram illustrating phasors of the interconnection system of the present invention.
  • Fig. 1 shows an electrical power interconnection system 100 which includes a variable frequency transformer 102 and a control system 104.
  • variable frequency transformer 102 is connected by 3-phase lines RA, RB, RC (included in line 26) to first AC Power system 22 and by 3-phase lines SA, SB, and SC (included in line 28) to second AC Power System 24.
  • first electrical system and the second electrical system may have and likely do have a differing electrical characteristic, such as differing electrical frequency.
  • variable frequency rotary transformer 102 includes both a rotary transformer assembly 105 and a torque control unit 106 (also known as the rotor drive section). Details of rotary transformer assembly 105 and torque control unit 106 are below described in more detail in connection with Fig. 2.
  • control system 104 includes both a slow power control unit 107; a fast speed control unit 108; and a power transducer 109
  • Slow power control unit 107 is connected to receive the voltage V 1 carried on line 26 from first AC Power System 22 and the voltage V 2 carried on line 28 to second AC Power System 24, as well as (via power transducer 109) a signal indicative of measured power P 1 transmitted on line 26
  • Slow power control unit 107 is also connected to receive a power order input signal P 0 and to output a signal ⁇ 0 to fast speed control unit 108
  • Fast speed control unit 108 in turn receives a signal ⁇ r from speed transducer 111 and outputs a drive signal T 0 to torque control unit 106
  • rotary transformer assembly 105 includes both a rotor subassembly 110 and a stator 112
  • Rotor subassembly 110 includes collector rings 114 (also known as slip rings) and rotor cage section 116
  • collector rings 114 also known as slip rings
  • rotor cage section 116 Three-phase lines RA, RB, RC leading from first AC Power System 22 are connected to collector rings 114
  • three-phase lines SA, SB, and SC leading to second AC Power System 24 are connected to stator 112
  • Rotor subassembly 110 has speed transducer 1 11 mounted proximate thereto for generating the angular velocity signal ⁇ r indicative of the angular velocity of the rotor
  • rotary transformer assembly 105 is wound with sixty degree phase belts, with rotor windings being labeled as RA+, RC-, RB+, RA-, RC+, and RB- and stator windings labeled as SA+, SC-, SB+, SA-, SC+, and SB- It should be understood that the invention is not limited to a sixty degree phase belt-wound system, rather the principles of the invention are applicable for rotary transformer assemblies of phase two and greater
  • Rotor assembly 110 is rotatable about its axis RX in both clockwise direction CW and counter-clockwise direction CCW Rotation of rotor assembly 110 is effected by rotor drive section 106
  • Rotor drive section 106 is shown symbolically in Fig 2 as a cylindrical section mounted on rotor assembly 110
  • rotor drive section 106 of Fig 2 generally depicts various alternative and different types of drive mechanisms for causing rotation of rotor assembly 110
  • rotor drive section 106 includes an actuator and some type of linkage (e g , gearing) which interfaces with rotor assembly 1 0
  • rotor d ⁇ ve section 106 comprises a worm gear drive arrangement as shown in Fig 3A and Fig 3B and discussed hereinafter
  • rotor drive section 106 comprises an actuator such as a stepper motor acting through a radial (e g, spur) gear a direct d ⁇ ve arrangement, a hydraulic actuator turning a gear on rotor assembly 110, or
  • Control system 104 bi-directionally operates the rotor assembly 110 (through rotor drive section 106) for transferring power from first AC Power System 22 to second electrical system 24, or vise-versa
  • an operator sets the power order input signal P 0 in accordance with a predetermined power transfer requirement prearranged between AC Power Systems 22 and 24
  • Setting power order input signal P 0 can be accomplished by adjusting a knob or inputting data at an operator control panel or operator workstation CP to generate signal P 0 indicative of the ordered power.
  • control panel CP is remotely located from interconnection system 100
  • Slow power control unit 107 compares the power order input signal P 0 with the measured power transfer signa] P in order to produce a requested angular velocity signal ⁇ 0 .
  • the measured power transfer signal P 1 is obtained from the three lines 26 by power transducer 109.
  • Power transducer 109 can be any one of a number of conventional instruments, with the man skilled in the art readily appreciating how to obtain signal P t
  • slow power control unit 107 is an integrator which measures a difference between order power signal P 0 and measured power signal P., (i.e., P 0 - P ⁇ and puts the result into an integrator function to generate requested angular velocity signal ⁇ 0 .
  • Slow power controller 107 has a very low gam to prevent interference of natural AC system dynamics generally occurring above 3 rad/sec (as described below)
  • Fast speed controller 108 receives both the requested angular velocity signal ⁇ 0 and a measured angular velocity signal ⁇ r .
  • the requested angular velocity signal ⁇ 0 is generated by slow speed controller 107 as aforedescribed.
  • the measured angular velocity signal ⁇ r is obtained from speed transducer 111.
  • Fast speed controller 108 generates a drive signal (also known as the torque order signal T 0 ) on line 134 so that u promptly equals ⁇ 0 .
  • the man skilled in the art knows how to operate conventional motor drivers as fast speed controller 108 to use signals ⁇ r and tij, to generate the drive signal T 0 .
  • fast speed controller 108 operates to adjust the d ⁇ ve signal T 0 on line 134 to torque control unit 106 such that the actual speed ⁇ r of rotor assembly 110 follows the ordered speed ⁇ 0
  • the closed-loop bandwidth of fast speed controller 108 should exceed the highest natural oscillatory frequency of rotor assembly 110, including its reaction to the transmission network into which it is integrated, and is generally less than 100 rad/sec Typically, the natural modes of oscillation will range from about 3 rad/sec through 50 rad/sec, and are usually less than 30 rad/sec
  • a phase lag from a change in ordered speed ⁇ 0 to actual speed ⁇ r of rotor assembly 110 is less than 90 degrees for sinusoidal disturbances. Ensuring this bandwidth of response will in turn ensure that all such natural modes of oscillation will experience beneficial damping from the control system
  • the directionality (e g, polarity) of the drive signal T 0 on line 134 is in accordance with the direction of power flow (e g , in accordance with whether power is flowing from AC Power System 22 to AC Power System 24 or vise-versa)
  • the magnitude of the drive signal T 0 on line 134 is used by rotor drive section 106 to increase or decrease the speed of rotor assembly 110 in order to match the difference between the frequencies of AC Power System 22 and AC Power System 24
  • drive signal T 0 on line 134 is applied to torque control amplifier 150 Power is supplied to torque control amplifier 150 by torque control power source 152, whereby using drive signal T 0 on line 134 the torque control amplifier 150 outputs the three phase signals TA, TB and TC to torque control unit 106
  • TA refers collectively to TA+ and TA-
  • TB refers collectively to TB+ and TB-
  • Fig 9 is a phasor diagram drawn with respect to a reference phasor V ref
  • Fig 9 shows voltage phasor y representing the voltage ⁇ at AC Power System 22.
  • voltage phasor V 2 representing voltage V 2 at AC Power System 24, as well as the phase angle ⁇ 1 of ac voltage on lines 26 with reference to phasor V ref , the phase angle ⁇ 2 of ac voltage on lines 28 with reference to phasor V ref , and 6
  • the angular positioning 8- of the rotor assembly 110 relative to the stator 112 is also shown in Fig. 2, it being understood from conventional practice that ⁇ r is zero when RA+ lines up exactly with SA+.
  • An objective of interconnection system 100 is to cause the rotational speed and angular position ⁇ r of variable frequency transformer 102 to be such that a desired power (i e , indicated by order power signal P 0 ) is transferred through interconnect system 100 between AC Power System 22 and AC Power System 24
  • interconnect system 100 controls angle ⁇ r (see Fig. 9) so that measured power signal P., matches the order power signal P 0 .
  • Drive signal T 0 on line 134 is used to adjust the angular relationship ⁇ r of rotor assembly 110 relative to stator 112, so that the speed and angle of rotary transformer 102 enable transmission of power at the ordered power level
  • Equation 1 The power transfer through interconnect system 100 is approximated by Equation 1 :
  • V 1 voltage magnitude on lines 26
  • V ref ⁇ 2 phase angle of ac voltage on lines 28 with reference to reference phasor
  • angle ⁇ net must have an absolute value significantly less than 90°, which means that power transfer will be limited to some fraction of the maximum theoretical level given by Equation 2 Within this range, the power transfer follows a monotonic and nearly linear relationship to the net angle, which can be approximated by Equation 4
  • ⁇ (t) frequency of ac voltage on line 26 as a function of time
  • ⁇ 2 (t) frequency of ac voltage on line 28 as a function of time
  • ⁇ r (t) frequency of rotor assembly 110 as a function of time
  • the through power is directly affected by the time-integral of shaft speed of rotor assembly 110 over time
  • This characteristic perm its a power- regulating control loop to be implemented in the present invention by measuring the through power (P ⁇ and adjusting the order for shaft speed ( ⁇ 0 )
  • the bandwidth of this power regulator well below that of the lowest oscillatory mode on the system (typically below 3 rad/sec)
  • the fast power-limit function is used to override the normal slow power regulator when the measured power exceeds the limit computed from measured voltages
  • the limit will be some fraction of the maximum theoretical power as indicated by Equation 6
  • phase refers to electrical phase If there are more than two poles, the relationship between mechanical degrees on rotor assembly 110 and electrical degrees is
  • the angular position of rotor assembly 110 may be maintained, advanced, or retarded at will
  • the phase shift is accomplished by changing rotor angular position and thus modifying the mutual inductances among the phases of interconnection system 100
  • the number of poles (NP) rotary transformer 105 is typically dependent upon system parameters, such as the number of possible air gaps
  • a high pole number (high NP) can greatly reduce the number of mechanical degrees (NMD) of angular shift required to achieve the electrical shift
  • a -30 to +30 degree electrical shift is only -2 to +2 degrees of mechanical shift on a 30 pole wound-rotor motor
  • Fig. 3A and Fig. 3B show electrical power interconnection system 100 having a specific rotor drive section (torque control unit) 106'.
  • Rotor drive section 106' employs worm gear 160 meshing with rotor radial gear 162 as a linkage, and additionally employs worm gear servo driver 164 (e g , a stepper motor) as a ⁇ actuator
  • Fig 3A and Fig 3B show specific mounting structure of rotor assembly 110, particularly thrust and radial bearing 170 and top radial bearing 172 which facilitate both placement and rotation of rotor assembly 110
  • An advantage of rotor drive section 106' is that the worm gear drive tends to be self-locking Should its associated servo driver 164 fail to turn, rotor assembly 110 will be locked in position until the electrical phase error reaches 360 degrees At such time protective relaying will take interconnection system 110 off-line
  • rotor drive section 106' of Fig. 3A and Fig 3B provides a solid connection of rotor assembly 110 to worm gear 160
  • solid connection need not necessarily occur for other embodiments
  • a torsion spring/damper system is inserted between the worm gear 160 and rotor assembly 110 to adjust mechanical dynamics
  • the worm gear-based rotor drive section 106' displaces the phase (for example, 20 electrical degrees), then the combination of electrical energy and mechanical energy is tuned to match the time constants of the load being fed The result is a uniform power input on the utility side and stabilization of the system load
  • Fig 7A, Fig 7B, and Fig. 7C show specific implementations of rotor drive sections, generally represented by Fig 7, which implementations are illustrated as rotor drive sections 106"A, 106"B, and 106"C, respectively
  • Fig 7A, Fig 7B, and Fig 7C are illustrations of embodiments in which the rotor drive sections are integrated in the rotor assembly 110 and stator 112 of rotary transformer 110
  • Fig 7A illustrates a squirrel cage inductor embodiment
  • Fig 7B illustrates DC-excited rotor (synchronous) embodiment
  • Fig 7C illustrates a wound rotor AC embodiment
  • rotor drive sections 106"A, 106"B, and 106"C employ a two-pole rotor/stator configuration within a four-pole rotor/stator configuration
  • rotor assembly 110" is seen to have, on its outer periphery, the same two-pole rotor windings as shown in Fig 2 (such common rotor windings being shaded).
  • rotor assembly 110" has eight four-pole rotor windings (located at a smaller radius from the center of rotor assembly 110" than the two-pole rotor windings, the four-pole rotor windings being unshaded).
  • Stator 112" has, on its inner periphery, the same two-pole stator windings as shown in Fig. 2 (such common stator windings also being shaded).
  • stator 112" has eight four-pole stator windings (located at a larger radius from the center of rotor assembly 110" than the two-pole stator windings, the four-pole stator windings being unshaded).
  • the four- pole stator windings are connected to the lines TA+, TB+, TC+, TA-, TB-, TC- emanating from torque control amplifier 150 (see Fig. 2), and the connections of RA, RB, RC, SA, SB, SC are as shown in Fig. 2.
  • the four-pole rotor windings are shorted upon themselves to form a squirrel cage induction motor.
  • speed control unit 108 In the DC-excited rotor (synchronous) embodiment of Fig. 7B, speed control unit 108 generates a further signal E fdo (field voltage) which is applied to exciter amplifier 700B.
  • Exciter amplifier 700B derives its power from exciter power source 702B, and outputs signals DC+ and DC- to a slip ring assembly 114B having two slip rings. Placement of the slip rings in slip ring assembly 114B is understood from collector rings 114 of Fig. 2
  • speed control unit 108 In the wound rotor AC embodiment of Fig. 7C, speed control unit 108 generates a further signal TR 0 (rotor current signal) which is applied to rotor excitation amplifier 700C.
  • Rotor excitation amplifier 700C generates the three phase signals TRA, TRB, and TRC which are applied to three slip rings comprising slip ring assembly 114C.
  • the flux in the air gap (between rotor and stator) for the four-pole configuration rotate only half as fast as the flux for the two-pole configuration.
  • the influence of the four-pole flux upon the two-pole configuration has no average value, but only a "beat" value. In other words, if the flux of the two-pole configuration were rotating at 1 Hz, and the flux of the four-pole configuration were rotating at 0.5 Hz, the two-pole configuration will see a beat frequency of 0.5 Hz.
  • Fig. 7A, Fig. 7B, and Fig. 7C show a two-pole and " four-pole configuration
  • the second configuration could be larger than four poles (e.g, increase the difference of the number of poles of the two configurations), so as to increase the beat frequency between the two configurations to keep pulsations low.
  • Wth the embodiments of Fig. 7A, Fig. 7B, and Fig. 7C average torque is controlled using both sets of windings (the two-pole windings and the four- pole windings) independently.
  • the four-pole windings could be used to perform the same function of torque control unit 106 (also known as the rotor drive section) of Fig. 2.
  • Fig. 7A sees average torque from both the "S" windings and from the 'T" windings on stator 112. Consequentially, control unit 108 must unscramble these two effects, which the man skilled in the art will readily appreciate and how to resolve.
  • Fig 4 shows incorporation of electrical power interconnection system 100 of the present invention in a substation 200 Substation which electrical interconnects a first electrical system 222 and to a second electrical system 224
  • first electrical system 222 labeleled as AC Power System #1
  • second electrical system 224 labeleled as AC Power System #2
  • both systems/utilities 222 and 224 happen to operate at 230kV
  • other appropriate voltages are employed in other embodiments
  • Power supplied by system 222 enters substation 200 of Fig 4 through series power capacitor 230 (20 Mvar) and is stepped down via 100 MVA generator step-up (GSU) transformer 232 from 230kV to 15kV Stepped- down power from transformer 232 is applied on input line 234 to variable frequency transformer 102 of interconnection system 100
  • input line 234 is actually the three phase lines RA, RB, and RC connected to collector rings 114
  • An electrical field and power are established on rotor assembly 110, are transferred to stator 112, and transferred from stator 112 on output line 236 at 15kV
  • output line 236 is actually the three phase lines SA, SB, and SC Power output from stator 112 on output line 236 is stepped up at 100 MVA generator step-up (GSU) transformer 238 from 15kV to 230kV Stepped-up power from transformer 238 is then applied through series power capacitor 240 (20 Mvar) to system 224
  • controller 104 monitors the frequencies of both system 224 and system 222 as those frequencies wander through their differing and respective frequency ranges As the power flow is monitored, controller 104 generates a drive signal for adjusting the angular position of rotor assembly 110 so that electrical power may be transmitted from system 222 to system 224
  • interconnection system 100 would require a .2 Hz change for power transfer from system 222 to system 224.
  • rotary transformer 105 should typically also be capable of ⁇ 0 50 Hz, or a speed range from +30 to -30 revolutions per minute (RPMs) for the 2-pole equivalent.
  • Fig. 5 shows the linear relationship between control torque and through power between the first and second electrical systems
  • the electromagnetic torque developed is constant
  • the RPM ( ⁇ r ) required to match them increases
  • the product of the torque and speed is power required by the drive
  • Fig. 6 shows the practical capability curves of the drive system of the present invention.
  • the relationship between control torque and through power was shown in Fig. 5.
  • 'Through Power is a machine thermal rating if maximum torque is provided by an electromechanical drive (e.g , a maximum thrust rating for worm gear bearing)
  • 'Through Power is essentially material-limited, whether insulation class for a winding or a material stress allowable, respectively.
  • mechanical torque of the rotary transformer is controlled to achieve an ordered power transfer from stator to rotor windings.
  • the present invention contrasts with prior art techniques which controlled power transfer from rotor to stator windings for the purpose of controlling torque applied to the load (and thereby its speed).
  • both rotor and stator windings are rated for full power transfer, whereas in prior art applications the rotor winding was rated only for a small fraction of the stator winding.
  • the present invention avoids the prior art HVDC need to closely coordinate harmonic filtering, controls, and reactive compensation.
  • the present invention also advantageously provides a one-step conversion.
  • interconnection system 100 of the present invention performs continuous phase shifting by controlling rotor angle ⁇ r (i.e., the angular position of rotor assembly 110).
  • Interconnection system 100 permits continuous adjustment of electrical phase by virtue of its potential 360 degree rotation, making the system a very low frequency synchronous converter.
  • interconnection system 100 can be repetitively displaced through large angular displacements to accomplish very large electrical phase shifts in a rapidly changing power condition on a large system.
  • rotor assembly 110 is not rotated at a constant angular velocity, but instead is rotated at a continuously variable angular velocity as required by control system 104.
  • bi-directional angular velocity is achieved as rotor assembly 110 is rotatable in both clockwise direction CW and counter-clockwise direction CCW as shown in Fig. 2.
  • rotary transformer 105 of interconnection system 100 typically runs, forward or backward, at less than 50 RPM.
  • Interconnection system 100 provides accurate and reliable phase shift control, with the ability to follow frequency drift and control phase in all four quadrants of control. Thus, interconnection system 100 not only transfers power, but can also modify power rapidly by accomplishing phase shift under load.
  • interconnection system 100 can also serve as an energy storage system.
  • Interconnection system 100 can be used to store energy by rotational inertia, to average large pulsating loads, similar to those present in arc melters for steel processing.

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  • Engineering & Computer Science (AREA)
  • Power Engineering (AREA)
  • Supply And Distribution Of Alternating Current (AREA)
  • Control Of Ac Motors In General (AREA)

Abstract

Système d'interconnexion électrique (100) comprenant un transformateur rotatif (102) à fréquence variable et un système de régulation (104). Le système de régulation (104) règle une position angulaire du transformateur rotatif (102) de sorte que la puissance mesurée (P1) transférée d'un premier système électrique (22) à un second système électrique (24) corresponde à une puissance commandée spécifiée (P0). Le transformateur rotatif (102) comprend un ensemble rotor (110) et un stator (112), le système de régulation (104) réglant en permanence une intégrale de temps de la vitesse du rotor. Le système de régulation (104) comprend une première unité de régulation (107) et une seconde unité de régulation (108). La première unité de régulation (107) compare la puissance commandée spécifiée (P0) à la puissance mesurée (P1) afin de générer un signal φ0 requis de vitesse angulaire. La seconde unité de régulation (108) compare le signal φ0 requis de la vitesse angulaire à un signal φr mesuré de la vitesse angulaire du transformateur rotatif afin de générer un signal (T0) de commande convertisseur par rapport à une unité de régulation de couple (106), ce qui permet de réguler le positionnement angulaire (υr) de l'ensemble rotor (110) par rapport au stator (112). Selon diverses réalisations, l'unité de régulation de couple (106) est intégrée à l'ensemble rotor (110) et au stator (112) du transformateur rotatif (102).
PCT/US1996/015216 1995-10-31 1996-09-20 Systeme d'interconnexion pour la transmission de puissance entre des systemes electriques WO1997016885A1 (fr)

Priority Applications (2)

Application Number Priority Date Filing Date Title
EP96933092A EP0800717A4 (fr) 1995-10-31 1996-09-20 Systeme d'interconnexion pour la transmission de puissance entre des systemes electriques
BR9606958A BR9606958A (pt) 1995-10-31 1996-09-20 Sistema de interligação para transmissão de energia entre sistemas elétricos

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
US55094195A 1995-10-31 1995-10-31
US08/550,941 1995-10-31

Publications (1)

Publication Number Publication Date
WO1997016885A1 true WO1997016885A1 (fr) 1997-05-09

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EP (1) EP0800717A4 (fr)
CN (1) CN1061485C (fr)
BR (1) BR9606958A (fr)
FR (1) FR2740629B1 (fr)
MY (1) MY119005A (fr)
WO (1) WO1997016885A1 (fr)

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EP2833533A1 (fr) * 2012-03-27 2015-02-04 Hitachi Metals, Ltd. Dispositif de conversion de fréquence

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FR2803124B1 (fr) * 1999-12-22 2002-03-08 Leroy Somer Convertisseur de frequence alimente par un reseau industriel pour delivrer une basse tension a une frequence plus elevee que celle dudit reseau
US8054011B2 (en) * 2009-06-25 2011-11-08 General Electric Company Variable frequency transformer having multiple horizontal rotary transformers with common controls and voltage infrastructure and method
US20110141771A1 (en) * 2010-12-07 2011-06-16 Karl Kyrberg Electric power system including power converter and rotary transformer and method of assembling same
CN104080067A (zh) * 2013-03-29 2014-10-01 上海城际互通通信有限公司 一种nfc方式的自动呼转方法
CN108987080A (zh) * 2018-07-30 2018-12-11 张淼 一种旋转磁场电力变压器
CN110112743B (zh) * 2019-04-04 2023-04-28 上海电力学院 一种隔离型变频变压器及其启动控制和扩容方法
CN110224614A (zh) * 2019-06-25 2019-09-10 天津清传科技有限公司 一种电源旋转变换装置

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US4517471A (en) * 1981-07-29 1985-05-14 Anton Piller Gmbh & Co. Kg Rotary converter machine for direct transfer of electric energy by flux linkage between windings on a stator pack
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EP2833533A1 (fr) * 2012-03-27 2015-02-04 Hitachi Metals, Ltd. Dispositif de conversion de fréquence
EP2833533A4 (fr) * 2012-03-27 2017-03-15 Hitachi Metals, Ltd. Dispositif de conversion de fréquence
US9755552B2 (en) 2012-03-27 2017-09-05 Hitachi Metals, Ltd. Frequency converter

Also Published As

Publication number Publication date
CN1166242A (zh) 1997-11-26
FR2740629B1 (fr) 1998-04-03
EP0800717A4 (fr) 2007-01-03
MY119005A (en) 2005-03-31
EP0800717A1 (fr) 1997-10-15
CN1061485C (zh) 2001-01-31
BR9606958A (pt) 1997-10-28
FR2740629A1 (fr) 1997-04-30

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