WO2011111058A2 - Banc de condensateurs commutés - Google Patents

Banc de condensateurs commutés Download PDF

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Publication number
WO2011111058A2
WO2011111058A2 PCT/IN2010/000836 IN2010000836W WO2011111058A2 WO 2011111058 A2 WO2011111058 A2 WO 2011111058A2 IN 2010000836 W IN2010000836 W IN 2010000836W WO 2011111058 A2 WO2011111058 A2 WO 2011111058A2
Authority
WO
WIPO (PCT)
Prior art keywords
capacitor
switch
bank
capacitor bank
switching combinations
Prior art date
Application number
PCT/IN2010/000836
Other languages
English (en)
Other versions
WO2011111058A3 (fr
Inventor
Venkatesh Raghavan
Original Assignee
Epcos India Private Limited
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 Epcos India Private Limited filed Critical Epcos India Private Limited
Publication of WO2011111058A2 publication Critical patent/WO2011111058A2/fr
Publication of WO2011111058A3 publication Critical patent/WO2011111058A3/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
    • H02J3/18—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
    • 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

  • a reactive power compensating equipment is fixed shunt capacitors. These are fixed capacitors connected in parallel with the loads requiring capacitive reactive power. These capacitors are either single phase or multi phase and multi phase capacitors are configured as either star (Wye) or delta. While this type of reactive power compensation is very simple, cost effective, but has the disadvantage of being able to deliver only fixed reactive power. To overcome this problem to an extent switched shunt capacitor banks are used.
  • the total capacitor bank is split into multiple steps with a switching device for each step. All steps are connected in parallel and required step is switched ON or OFF depending upon reactive power requirement.
  • each capacitor step is provided with a series switching device.
  • a first capacitor of value Ci is provided in series with a first switch, and a second capacitor of value C 2 in series with a second switch.
  • the said capacitor bank has two steps each of which can be activated separately by switching respective switches.
  • the first capacitor gets connected to the circuit and delivers an output reactive power depending upon the system voltage and frequency.
  • the reactive power output will be
  • Qi is the reactive power delivered
  • Vc is the voltage across capacitors
  • each of the above identified equipment for power compensation may be either complex, expensive and/or generate harmonics and increased power losses.
  • switched shunt capacitors are the most popular owing to their simplicity and lower cost. However, the lowest value of capacitance is limited by the lowest capacitor value and the number of switching combinations available for limited number of steps.
  • the capacitors may have residual charges during switching. This leads to reduced life of the capacitors and the overall system. This residual charge may also lead to inrush current spikes during switching operations, creating current and voltage transients which are injurious to the system and other connected equipment.
  • VL is the line voltage and II is the line current.
  • capacitor bank providing an efficient and safe means for providing wider range, increased switching combinations and increased resolution, which may help in providing reactive power compensation to varying reactive loads.
  • An object of the invention is to provide a switching system for power capacitors which provides wider range of output reactive power for a given number of capacitor steps.
  • Another object of the invention is to provide a switching system for power capacitors, which uses switches of lower current rating to switch capacitors. Another object of the invention is to provide a switching system for power capacitors which enhances the life of switches and capacitors.
  • Yet another object of the invention is to provide an economical, efficient and safe capacitive reactive power compensation system.
  • Fig. 1 illustrates a two step switched capacitor bank according to one embodiment of the present invention.
  • Fig. 2 illustrates a three step switched capacitor bank as per one embodiment of the present invention.
  • Fig. 3 illustrates a two step switched capacitor bank having damping / detuning reactance according to one embodiment of the present invention.
  • Fig. 4 illustrates a three phase two step switched capacitor bank in delta configuration according to one embodiment of the present invention.
  • Fig. 5 illustrates a three phase two step switched capacitor bank in star configuration according to one embodiment of the present invention.
  • a switched capacitor bank operable in multiple switching combinations in an alternating current power supply is described.
  • the capacitor bank is described having two capacitor steps in a single phase power supply.
  • a polyphase switched capacitor bank is provided.
  • capacitors may be used.
  • the switches used may include mechanical or solid state switches.
  • the capacitor bank comprises of a first capacitor (102) having one terminal connected to a power line (141) and the other terminal connected to a neutral line (143) through a first switch (1 12). This provides for a capacitor step of the switched capacitor bank.
  • a second capacitor (104) having one terminal connected to the neutral line (143) and the other terminal connected to the said one terminal of the first capacitor through a second switch (1 14) is provided thus providing another capacitor step of the switched capacitor bank.
  • a third switch (1 16) is provided across the junction of the first capacitor (102) with the first switch (1 12) and the junction of the second capacitor (104) with the second switch (1 14).
  • the said switches may be switched manually or automatically to provide for various switching combinations.
  • the switched capacitor bank of this configuration facilitates six switching combinations out of which four are output combinations. The output combinations imply different power output.
  • the various switching combinations on which the said switched capacitor bank may operate comprises of a first switching combination having the third switch in closed position while the second switch and the first switch in open position.
  • This switching combination provides for series connection of the said first capacitor and the said second capacitor.
  • the voltage across each capacitor will be less than the system voltage, for which each capacitor is rated, since the system voltage would get divided between the two capacitors.
  • the current through the capacitor will also be lower than when each capacitor is individually connected to the system. This will enhance the operating life of the capacitors since in this switching combination the thermal and dielectric stresses are much lower than nominal stresses. Further, this switching combination also helps in providing a net capacitance lower than that of the individual capacitor steps. Which implies reactive power -lower than that provided by individual capacitor steps. Thereby an increased overall range of capacitance may be derived from such switched capacitor bank. It may be noted that the number of switching combinations of the capacitor bank is increased to correspondingly increase the range of reactive power delivered by the capacitor bank.
  • a second switching combination may be provided by having the second switch in closed position while the first switch and the third switch in open position. In such switching combination, only the second capacitor is brought in the active circuit. Further, the first switch in closed position while second switch and the third switch are in open position provide for a third switching combination having the first capacitor in the active circuit. It may be noted that the value of the lowest value of the capacitance possible is not restricted by the least value of the capacitor available, since the series combination of the said capacitors provides for a lesser value of the capacitance as compared to individual capacitor steps.
  • the second capacitor may also be shorted by closing the first switch and the third switch while the second switch is open. This allows the first capacitor to be in the circuit while the second capacitor is shorted allowing for the quick discharge thereof.
  • This switching combination is termed the sixth switching combination.
  • a switched capacitor bank having multiple steps allowing multiple switching combinations. Across the switched capacitor bank as shown in figure 1 , at least one twig containing a capacitor and a switch in series is added.
  • Figure 2 shows an exemplary embodiment herein where a three step version of the said capacitor bank is provided.
  • a three step version of the said capacitor bank For the three step version one twig containing a third capacitor and a fourth switch in series, connected across the power-line and the neutral-line is added to an existing two step version of the capacitor bank as in figure 1.
  • four switches namely (212, 214, 216 and 218) along with three capacitors (202, 204 and 206)
  • thirteen switching combinations are provided, excluding the switching combination having all the four switches open.
  • This embodiment facilitates for thirteen switching combinations out of which nine are output combinations. More particularly, all the switching combinations available in the two step version of the said capacitor bank are provided, in which the fourth switch (218) would be in open position. Further, multiple switching combinations would arise by switching combination of switches when the fourth switch (218) is in closed position.
  • the fourth switch in closed position while the first switch, the second switch and the third switch are open provides for a first additional switching combination having the third capacitor in the circuit.
  • the fourth switch along with first switch in closed position while the second switch and the third switch are open provides for a second additional switching combination having the first capacitor in parallel with the third capacitor in the circuit.
  • the fourth switch along with second switch in closed position while the third switch and the first switch are open provides for a third additional switching combination having the second capacitor in parallel with the third capacitor connected in circuit.
  • the fourth switch along with the first switch and second switch in closed position while the third switch is open provides for a fourth additional switching combination having the first capacitor, the second capacitor and the third capacitor in parallel connected in the active circuit.
  • the fourth switch along with the third switch in closed position while the second switch and the first switch are open providing for a fifth additional switching combination having the third capacitor in parallel to the series combination of the first capacitor and the second capacitor.
  • each of the capacitors present may have a reactor in series connected with each, to one of their terminals to allow for damping, detuning and current limiting.
  • the reactors may be of same or of different values.
  • the reactor also allows modifying the tuning frequency of the circuit. This further enhances the applicability of the said capacitor bank for the power compensation since the occurrence of the surge and spikes in the current may be reduced and amplification of harmonics is minimized.
  • the value of series reactor may be specified by tuning frequency or impedance of the reactor as a proportion of the impedance of capacitor concerned.
  • Some of the standard tuning frequencies used with 50 Hz power systems are 133.6 Hz, 188.9 Hz, 204 Hz, 210 Hz, 1 1 18 Hz and these correspond to 14%, ' 7%, 6% , 5.67% and 0.2% impedance of the capacitor bank. These correspond to 2.7, 3.8, 4.1 , 4.2 and 22.4 multiples of fundamental frequency.
  • FIG. 3 shows the version of the capacitor bank unit having two capacitor steps along with the damping reactors.
  • a damping reactor each is connected in series to each of the said capacitors, the first capacitor 302 and the second capacitor 304.
  • the corresponding reactors 322 and 324 are connected to one of the terminals of the said capacitors respectively.
  • a damping reactor may also be connected in series to the third capacitor.
  • a polyphase switched capacitor bank is provided.
  • the polyphase two step switched capacitor bank is explained with reference to an exemplary embodiment having three phases as shown in figure 4 and figure 5.
  • the figure 4 shows the exemplary embodiment of the invention having the delta configuration of the said three phase capacitor bank.
  • the said bank comprises a first capacitor (402a, 402b, 402c) having one terminal connected to one phase and the other terminal connected to the other cyclically consecutive phase through a first switch (412a, 412b, 412c).
  • the bank comprises of a second capacitor (404a, 404b, 404c) having one terminal connected to the said cyclically consecutive phase and the other terminal connected to the said one terminal of the first capacitor through a second switch (414a, 414b, 414c) and a third switch (416a, 416b, 416c) provided across the junction of the first capacitor with the first switch and the junction of the second capacitor with the second switch.
  • the switches present between each cyclically consecutive phase may be gang operated. Such switching of the various switches would lead to various switching combinations.
  • Various switching combinations would be similar to the single phase switched capacitor bank as explained above.
  • the third switch between the phases 441a and 441b, ie. 416a, the third switch between phases 441 b and 441 c i.e. 416b and the third switch between phases 441c and 441 a, i.e. 416c all in closed position with the second switches and the first switches in open position provides for a first switching combination having the first capacitor and the second capacitor in series.
  • each phase of the said bank comprises of a first capacitor (502a, 502b, 502c) having one terminal of each connected to respective phase and the other terminal connected to the neutral line (543) through a first switch (512a, 512b, 512c). Further there is provided a second capacitor (504a, 504b, 504c) having one terminal connected to the neutral (543) and the other terminal connected to the said one terminal of the first capacitor through a second switch. Further, a third switch (516a, 516b, 516c) provided across the junction of the first capacitor with the first switch and the junction of the second capacitor with the second switch leading to multiple switching combination in three phase capacitor bank in star configuration.
  • the said exemplary embodiment is explained with reference to three phases it is obvious to a person skilled in the art that the said exemplary embodiment may be adapted to be used in four or more phases. In each case, the neutral of all phases would be common or joined.
  • polyphase multi step switched capacitor bank may also be provided by using the single phase version of the three step switched capacitor bank connected as explained above in a star or delta configuration.
  • Example 1 The capacitor bank with two equal steps
  • Reactive power of one of the capacitor step 52.5 kvar
  • Reactive power of another capacitor step 52.5 kvar

Landscapes

  • Engineering & Computer Science (AREA)
  • Power Engineering (AREA)
  • Ac-Ac Conversion (AREA)
  • Supply And Distribution Of Alternating Current (AREA)

Abstract

La présente invention concerne un banc de condensateurs commutés utilisable dans de multiples combinaisons de commutation dans une alimentation électrique à courant alternatif. De multiples combinaisons de commutation sont possibles, augmentant la plage de puissance réactive disponible pouvant être fournie et la plage de valeurs de capacité disponibles en utilisant un nombre limité d'éléments électriques. Certaines des combinaisons possibles de commutation réduisent la contrainte sur le condensateur, augmentant ainsi la vie utile. Une caractéristique pour une décharge rapide est disponible dans certaines combinaisons de commutation, optimisant ainsi la sécurité et facilitant des opérations de commutation fréquentes. Les combinaisons de commutation utilisent des commutateurs de capacité de courant plus faible pour fournir une sortie de puissance réactive capacitive requise à partir du banc de condensateurs.
PCT/IN2010/000836 2010-03-12 2010-12-21 Banc de condensateurs commutés WO2011111058A2 (fr)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
IN664/MUM/2010 2010-03-12
IN664MU2010 2010-03-12

Publications (2)

Publication Number Publication Date
WO2011111058A2 true WO2011111058A2 (fr) 2011-09-15
WO2011111058A3 WO2011111058A3 (fr) 2011-11-24

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Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2015091848A1 (fr) * 2013-12-18 2015-06-25 Eaton Industries (Austria) Gmbh Unité de régulation de tension électrique
EP2937976A1 (fr) * 2014-04-22 2015-10-28 Skf Magnetic Mechatronics Dispositif de commande de palier magnétique électronique avec dispositif de compensation de puissance réactive automatique
US11373811B2 (en) * 2019-08-08 2022-06-28 Nu-wave Technologies Corp. Electrical capacitor bank

Citations (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2802171A (en) * 1955-11-10 1957-08-06 Mc Graw Edison Co Arrangement for switching capacitors
US2917703A (en) * 1957-09-16 1959-12-15 Mc Graw Edison Co Capacitor switching control
US3053920A (en) * 1959-06-29 1962-09-11 Ajax Magnethermic Corp Control for electric furnace
US3513376A (en) * 1967-11-29 1970-05-19 Westinghouse Electric Corp High voltage to low voltage regulated inverter apparatus
US5134356A (en) * 1990-06-22 1992-07-28 Board Of Regents Of The University Of Washington Reactive power compensator
US5764501A (en) * 1992-04-06 1998-06-09 D.C. Transformation, Inc. Compact and efficient power transfer system and method
US20090128100A1 (en) * 2007-11-21 2009-05-21 Mitsubishi Electric Corporation Power system control apparatus and power system control method
US20100001698A1 (en) * 2008-07-02 2010-01-07 American Superconductor Corporation Static VAR Corrector

Patent Citations (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2802171A (en) * 1955-11-10 1957-08-06 Mc Graw Edison Co Arrangement for switching capacitors
US2917703A (en) * 1957-09-16 1959-12-15 Mc Graw Edison Co Capacitor switching control
US3053920A (en) * 1959-06-29 1962-09-11 Ajax Magnethermic Corp Control for electric furnace
US3513376A (en) * 1967-11-29 1970-05-19 Westinghouse Electric Corp High voltage to low voltage regulated inverter apparatus
US5134356A (en) * 1990-06-22 1992-07-28 Board Of Regents Of The University Of Washington Reactive power compensator
US5764501A (en) * 1992-04-06 1998-06-09 D.C. Transformation, Inc. Compact and efficient power transfer system and method
US20090128100A1 (en) * 2007-11-21 2009-05-21 Mitsubishi Electric Corporation Power system control apparatus and power system control method
US20100001698A1 (en) * 2008-07-02 2010-01-07 American Superconductor Corporation Static VAR Corrector

Cited By (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2015091848A1 (fr) * 2013-12-18 2015-06-25 Eaton Industries (Austria) Gmbh Unité de régulation de tension électrique
EP2937976A1 (fr) * 2014-04-22 2015-10-28 Skf Magnetic Mechatronics Dispositif de commande de palier magnétique électronique avec dispositif de compensation de puissance réactive automatique
US9966892B2 (en) 2014-04-22 2018-05-08 Skf Magnetic Mechatronics Electronic magnetic bearing controller with an automatic reactive power compensation device
US11373811B2 (en) * 2019-08-08 2022-06-28 Nu-wave Technologies Corp. Electrical capacitor bank
US11769636B2 (en) 2019-08-08 2023-09-26 Nu-wave Technologies Corp. Electrical capacitor bank

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