WO2011024167A1 - Système et procédé de contrôle de tension, utiles pour contrôler la tension sur un site utilisateur - Google Patents

Système et procédé de contrôle de tension, utiles pour contrôler la tension sur un site utilisateur Download PDF

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Publication number
WO2011024167A1
WO2011024167A1 PCT/IL2010/000693 IL2010000693W WO2011024167A1 WO 2011024167 A1 WO2011024167 A1 WO 2011024167A1 IL 2010000693 W IL2010000693 W IL 2010000693W WO 2011024167 A1 WO2011024167 A1 WO 2011024167A1
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WO
WIPO (PCT)
Prior art keywords
voltage
line
nominal
supplied
primary
Prior art date
Application number
PCT/IL2010/000693
Other languages
English (en)
Inventor
Shimon Limor
Original Assignee
Powersines Ltd.
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 Powersines Ltd. filed Critical Powersines Ltd.
Publication of WO2011024167A1 publication Critical patent/WO2011024167A1/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
    • H02J3/04—Circuit arrangements for ac mains or ac distribution networks for connecting networks of the same frequency but supplied from different sources
    • H02J3/06—Controlling transfer of power between connected networks; Controlling sharing of load between connected networks
    • 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
    • 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

  • the present invention is concerned with providing a variable voltage, for example a variable voltage system suitable for stabilizing the voltage supply especially to a home or other small consumer, such as a small workshop or office.
  • the mains voltage fed to a consumer's premises is invariably variable to a certain extent. This variability can be caused by fluctuations at the power stations or sub-stations and also by the variation in line losses dependent on the current drawn by other subscribers supplied by the same power lines or power grid.
  • electrical power consuming devices invariably are designed to operate over a range of voltages.
  • the efficiency of these devices and the KVA, KVAR, Current, power factors.... drawn by the devices varies with voltage supplied.
  • the secondary is wound and attached to oppose (and thus reduce) the line voltage supplied to the load. This provides a reduced voltage at the load.
  • the transformer input is disconnected from the return and short circuited, forcing the voltage on the secondary to zero.
  • the primary can then be short circuited. Shorting the primary does not require switching high currents through the short since the current in the primary is much lower than that in the secondary, which carries the full line current.
  • Such systems are especially suited for controlling the voltage for relatively large areas with multiple users.
  • Multiple transformer stages can be utilized in series to provide a greater variation in load voltages. For three phase, the configuration is repeated for each phase.
  • PCT Publication WO 2008/010213 the disclosure of which is incorporated herein by reference describes a three phase variable voltage control suitable for providing a variable voltage for start up for a motor in system in which secondaries of three transformers are placed in series with each of the lines and the primaries can be switched between phase to phase and phase to neutral. This allows for the injection of additive, subtractive and out of phase voltages to the line voltages.
  • Israel Patent 13307 when the line voltage is desired, the primary is disconnected and shorted to force a zero voltage on the secondary, which can also be shorted. Since the voltage control is originally designed for motor starting, the line current is not excessive and in any event the short on the primary is imposed at full voltage after high starting currents have fallen to steady state values.
  • An aspect of some embodiments of the invention is the provision of a system and method for providing a variable voltage, for example a variable voltage system suitable for stabilizing the voltage supply especially to a home or other consumer.
  • Some embodiments of the invention utilize a novel circuit design for varying the voltage, which design combines a minimum of commutation effects and ease of operation.
  • a method of reducing the energy used by a home or business having a mixed load and designed to operate from a given nominal mains voltage and a given tolerance comprising:
  • lowering the voltage supplied comprises inse ⁇ ing a voltage is series with the line which reduces the voltage fed to the load.
  • the supplied voltage is substantially below the mains voltage at least for values of mains voltage at the nominal voltage or above.
  • the supplied voltage is at least 5% or 3% below the mains voltage.
  • the range of supplied voltage is within ⁇ 3% of a target voltage over a range of variation of 11% of the mains voltage.
  • the target voltage is at least 4% or at least 5.5% below the nominal voltage. In some embodiments of the invention, the voltage supplied is below the nominal voltage for at least 60% of the range of the allowed variation of the mains voltage, when the allowed variation of the mains voltage is ⁇ 10%.
  • the voltage supplied is below the nominal voltage for at least 75% or 80% of the range of the allowed variation of the mains voltage.
  • the inserted voltage is derived from a same phase as the line voltage.
  • the line voltage is a three phase voltage and wherein the voltage inserted in any given phase is derived from the voltage of a different phase.
  • apparatus for controlling the voltage supplied to a load comprising:
  • At least one transformer having a primary and a secondary winding, the secondary winding being in series with a line transmitting power from an input line to the load and the primary being situated between the line transmitting power and either a neutral or another line,
  • the secondary is placed closer to the input than the primary, such that the voltage on the primary is effected by the voltage on the secondary.
  • the apparatus includes a switching arrangement that switches the primary from a first connection in which it is connected between the transmitting line and the neutral or other line and a second configuration in which it is not connected to the any live line.
  • the switching arrangement provides a short circuit on at least one of the primary and the secondary in the second configuration.
  • the switching arrangement provides for switching the primary from being connected from the primary to one other line of a three phase system to a second line of the three phase system
  • FIG. 1 is a schematic block diagram of a system for controlling the voltage input to a home, business or small factory, in accordance with some embodiments of the invention
  • FIG. 2 is a simplified circuit diagram of a voltage control module suitable for use in the system of FIG. 1;
  • FIG. 3 is a flow diagram of the operation of a voltage control module according to an embodiment of the invention.
  • FIG. 4 shows the output voltage as a function of input voltage for a particular choice of transformer ratio
  • FIGs. 5A and 5B show simplified circuit diagrams of variations of the circuit of FIG. 2;
  • FIGs. 6A and 6B are simplified circuit diagrams of voltage control modules suitable for use in a three phase system.
  • the present invention is concerned with providing a variable voltage, for example a variable voltage system especially suitable for stabilizing the voltage supply especially to a home or other small consumer, such as a small workshop or office.
  • a variable voltage for example a variable voltage system especially suitable for stabilizing the voltage supply especially to a home or other small consumer, such as a small workshop or office.
  • the prior art described above shows methodologies for controlling selected types of loads, mainly to provide stepped increases in voltage for start-up or specified voltages for specific loads
  • the present inventors have found that placing a voltage controller at each dwelling, business, etc., is a cost effective way to cut overall electrical usage by many percent. As an important economic by-product, the power savings are so great that construction of power plants costing many times the cost of installation of the devices is deferred.
  • An aspect of some embodiments of the invention is concerned with a system for controlling the voltage supplied to individual dwellings or small workshops. Generally such users receive one or three phase voltage with a current of up to 30 amps per phase.
  • the present inventors have surprisingly found that large savings in power and large reductions in KVA can be achieved by controlling the voltages of individual users. These savings are large enough to justify installation of voltage control devices at individual users.
  • line voltage at the user may vary over a considerable range.
  • a voltage regulator is added at an individual user level (i.e., less than about 30-40 amp per line service for mixed loads) to provide a smaller band of voltage variation, than that allowed by the standard of ⁇ 10%.
  • an individual user level i.e., less than about 30-40 amp per line service for mixed loads
  • In experiments such reduction has been shown to reduce energy consumption by an average of 15% and to reduce KVA by an average of 20% under certain load conditions and by more than 10% under mixed load conditions. This is a very significant reduction and easily justifies the capital cost of retrofitting homes, small businesses and workshops with voltage controllers. This saving is marked when the voltage supplied to the consumer is reduced by several percent from nominal.
  • the voltage to a user is set at a voltage which is less than the nominal voltage.
  • the present inventors have found that many large users of electricity within a home operate more efficiently and at lower KVA than when operated at nominal voltage.
  • One reason that these devices are designed in this way is that their ability to function at voltages much lower than the optimal voltages is limited.
  • such systems are designed to be most efficient at a lower voltage (say 215 volts for a 230 volt system) but not at the nominal voltage itself, since they would not operate well at a voltage that is 10% less than their optimal voltage.
  • the voltage reduction from nominal may be 5 or 10.
  • devices which have a higher efficiency at lower voltages are assigned to specific load circuits.
  • the voltage to these load circuits is reduced and controlled to a higher tolerance than the line voltage, while the other load circuits are not controlled.
  • the other circuits may be controlled to a voltage other than the line voltage.
  • An aspect of some embodiments of the invention is concerned with an apparatus and method for controlling line voltage.
  • one or more voltage varying units are placed between the line and the load.
  • Each of these units comprises a transformer whose secondary is in series with the load and a primary which is in parallel with the line at the input or the output.
  • Each of the units preferably further includes a switch which substantially simultaneously is capable of disconnecting the primary from the line and shorting the secondary. Shorting of the primary is not necessary.
  • the transformer is configured for either increasing or decreasing the voltage to the load.
  • a series of such units allows for reducing the variations of voltage on the load under varying line voltage conditions.
  • a controller is preferably provided which measures the incoming line voltage and determines which of the units should be operated to change the voltage delivered to the load to provide a narrower range of voltages to the load.
  • Fig. 1 is a schematic block diagram of a system 10 for controlling the voltage input to a home, business or small factory, in accordance with some embodiments of the invention.
  • a single phase circuit is shown. However, a separate or combined circuit can be provided for three phase systems, as described below.
  • a main line 12 supplies nominal voltage to a home or small business.
  • a voltage control module 14 controls the voltage as described below.
  • the voltage to all of the load lines is reduced to a voltage below nominal at which, for example, most motors work more efficiently most of the time.
  • This embodiment has the advantage of simplicity.
  • the system has the disadvantage of higher current and power requirement and potentially from somewhat lower efficiency since the voltage is lowered for devices which do not gain from such lowering.
  • the voltage when the voltage is above nominal it may be reduces, but to a voltage between the target low voltage and nominal or slightly above or below nominal.
  • the voltage is kept at the nominal voltage, but is controlled to reduce the spread of voltages.
  • control is applied only when the voltage is above nominal. At present, this would result in only a limited saving, based mainly on the reduction of energy use when the voltage is higher than nominal.
  • devices that are less voltage tolerant but which have a higher efficiency become available, such systems would be worthwhile.
  • Fig. 2 shows a first embodiment of a voltage control module 14. This system is applicable for controlling a single phase system or one phase of a three phase system.
  • a line voltage is applied between terminals 20 and 22. In general, the line voltage is applied to terminal 20 and terminal 22 is neutral.
  • a controller 24 receives an indication of the line voltage via a connection 26 and optionally compares it to a reference. Controller 24 controls two double pole single throw switches A and B, each of which comprises two switches al and a2 or bl and b2. When al is open, a2 is closed and vice versa. Similarly for bl and b2.
  • Voltage control module 14 also includes a first transformer 28, associated with switch 'A' and a second transformer 30 associated with switch 'B'.
  • the primary of each transformer is designated by the reference number prime (28', 30') and the secondary designated by the reference number double prime (28", 30").
  • transformer A has a 230:5 primary.secondary ratio and transformer B has a 230:10 primary:secondary ratio.
  • switch al is closed and switch a2 is open
  • the load voltage for nominal input
  • the load voltage can be controlled to within 215 ⁇ 2.5 volts according to the graph of Fig. 3.
  • the load and line voltages are the same and for higher voltages the load voltage is at least 15 volts less than the line voltage.
  • Fig. 4 is a simplified flow chart 100 of the operation of a voltage control system according to some embodiments of the invention.
  • the input line voltage is measured.
  • the input voltage is compared to a number of thresholds. As seen on Fig. 3, there is a transition between which sets of switches are open and closed to provide the desired tolerance and center voltage. Based on the voltage measured the switches that should be opened and closed are determined at 106. To avoid excessive switching some hysteresis may be built into the switching thresholds.
  • the switch configuration is compared to the current configuration, which is changed (at 110) as necessary.
  • the system continues to check the voltage and adjust the switches as necessary.
  • Fig. 5A shows a system similar to that of Fig. 2, except that the primaries are on the load side of secondaries. Although the voltages are slightly different from the system of Fig. 2, the operation is generally the same.
  • Fig. 5B shows yet another system similar to that of Fig. 2 except that each stage of transformers are in separate modules 50, 52 and the short circuits are across the primaries instead of the secondaries. The operation of this system is similar to that of those described above.
  • the circuits shown in Figs. 2 and 5A have a switch which short circuits the secondary when no voltage is to be injected into the line.
  • the secondary is not shorted and the primary is shorted instead as in Fig. 5B.
  • This configuration requires a shorting switch with a lower current capacity.
  • This type of circuit was used in the prior art to control large discharge lighting circuits since the current capacity of the short circuiting switches in Figs 2 and 5 A would be high and the switches large.
  • shorting the primary has somewhat greater commutation problems.
  • All of the circuits shown above are essentially single phase circuits. For three phases, these circuits can be placed in each line optionally with a single controller to control all of the switches.
  • Fig. 6A shows a three phase control circuit 200.
  • a three phase transformer 202 having primary windings A, B and C and corresponding secondary winding a, b and c.
  • Two three pole, single throw switches 204 and 206 switch the primaries between neutral N and one or another phase.
  • Switch 204 has two positions Kl and K2.
  • switch 206 has two positions K2 and K3. There are four modes of switching controlled by controller 26.
  • the primary secondary ratio is 400:20 (or
  • switch 204 is in position K2 and switch 206 is in position K4.
  • switch 204 In a second mode switch 204 is in position Kl and switch 206 is in position K4. In this case the primary of each line is connected from line to neutral and 5 volts, negative phase are fed back into each of the lines, so that each load to neutral is 225 volts,
  • switch 204 is in position Kl and switch 206 is in position K3. 15 volts is induced on each of the secondaries.
  • phase 2 leads phase 1 so that the sum of the load and the sum of the input and secondary voltages is 215 volts.
  • switch 204 is in position K2 and switch 206 is in position K3,
  • the load voltage will be 215v - 238v.
  • Fig. 6B shows a similar circuit to that of Fig. 6A, except that the primaries follow the secondaries. This operates in a manner similar to that of Fig. 6A, except that the since the secondary is always in series, there are fewer commutation problems.
  • substantially below the nominal means more than 2.5% below nominal.
  • the Power, KVAR and KVA were measured at 235 V (the actual line voltage) and at 215 V.
  • the load includes lighting, an electric clothes dryer, water heater, several air-conditioners, dishwasher, washing machine and (electric) oven.
  • the on times for each of the loads was varied to simulate the normal mix that might be expected over a day.
  • the reduction in power was between 10 and 16%; the reduction in KVAR, between 17 and 26% and the reduction in KVA between 11 and 16%.
  • the major saving is to the electric company.
  • a major cost for electric companies is the cost of generation plants and infrastructure. Studies have shown that this cost is generally between $2,000 and $6,000 per KW of capacity.
  • the peak power would be reduced by 2 KW or more, resulting in a capital saving in power plant construction of at least $4,000.
  • the line losses which are proportional to the square of the peak current, would also be reduced.

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  • Engineering & Computer Science (AREA)
  • Power Engineering (AREA)
  • Control Of Electrical Variables (AREA)

Abstract

L'invention concerne un procédé de réduction de l'énergie à usage domestique ou commercial et ayant une charge mixte, le procédé étant conçu pour fonctionner à partir d'une tension nominale donnée de réseau électrique et d'une tolérance donnée,et consistant à réduire la tension, destinée à un usage domestique ou commercial et ayant une charge mixte, en une nouvelle tension nominale, dans une tolérance qui est sensiblement inférieure à la tension nominale donnée; contrôler la tension fournie par rapport à une seconde tolérance qui est plus étroite que la tolérance donnée par des modifications de la tension du réseau électrique dans la tolérance, l'abaissement de la tension fournie consistant à introduire une tension en série avec la ligne, ce qui réduit la tension envoyée à la charge.
PCT/IL2010/000693 2009-08-26 2010-08-25 Système et procédé de contrôle de tension, utiles pour contrôler la tension sur un site utilisateur WO2011024167A1 (fr)

Applications Claiming Priority (2)

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US23692409P 2009-08-26 2009-08-26
US61/236,924 2009-08-26

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WO2011024167A1 true WO2011024167A1 (fr) 2011-03-03

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Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US8159175B2 (en) 2006-07-17 2012-04-17 Powersines Ltd. Variable voltage supply system
GB2494961B (en) * 2010-01-29 2014-08-27 C & C Marshall Ltd Voltage control apparatus

Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP1235322A2 (fr) * 2001-02-23 2002-08-28 Universidad Pontificia Comillas Stabilisateur de tension appliqué au transfert et à la distributrion d'énergie électrique
IL133307A (en) 1999-12-05 2003-05-29 Power Electronics Ltd Control system for discharge lighting bulbs
US20050237036A1 (en) * 2004-01-17 2005-10-27 Hap Nguyen Standby loss prevention module, transformer system including same, and methods relating thereto
WO2008010213A2 (fr) 2006-07-17 2008-01-24 Power Electronics Systems (2006) Ltd. Système d'alimentation à tension variable
US7330000B2 (en) 2006-02-03 2008-02-12 Shimon Limor Discharge lighting bulbs control system

Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
IL133307A (en) 1999-12-05 2003-05-29 Power Electronics Ltd Control system for discharge lighting bulbs
EP1235322A2 (fr) * 2001-02-23 2002-08-28 Universidad Pontificia Comillas Stabilisateur de tension appliqué au transfert et à la distributrion d'énergie électrique
US20050237036A1 (en) * 2004-01-17 2005-10-27 Hap Nguyen Standby loss prevention module, transformer system including same, and methods relating thereto
US7330000B2 (en) 2006-02-03 2008-02-12 Shimon Limor Discharge lighting bulbs control system
WO2008010213A2 (fr) 2006-07-17 2008-01-24 Power Electronics Systems (2006) Ltd. Système d'alimentation à tension variable

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US8159175B2 (en) 2006-07-17 2012-04-17 Powersines Ltd. Variable voltage supply system
GB2494961B (en) * 2010-01-29 2014-08-27 C & C Marshall Ltd Voltage control apparatus

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