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
  • H02J3/1885—Arrangements for adjusting, eliminating or compensating reactive power in networks using rotating means, e.g. synchronous generators
• • 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
  • H02P21/00—Arrangements or methods for the control of electric machines by vector control, e.g. by control of field orientation
• • 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 relates to the conditions for connection to the network of electrical energy production sites and relates more particularly to the improvement of the conditions for connection to the network of high power alternators.
• the connection to the network of a generator of the aforementioned type is ensured by means of a transformer.
• the generator delivers active power and reactive power to the network.
• the active power Pg supplied by the alternator is given by the relation:
• Vcp is the voltage across the network, at the transformer output
• I is the current
• ⁇ cp is the power factor seen by the network at the delivery point.
• Vg. cos ⁇ g Vcp.cos ⁇ cp
• the active power received by the network is equal to the active power supplied by the alternator, assuming that the transformer losses are negligible.
• Xt is the resistance of the transformer.
• the reactive power received by the network is equal to that supplied by the alternator, reduced by the consumption of the transformer in reactive power Xtl 2 .
• the active power and the reactive power of the network supplied by the generator are constant data which the electric energy supplier must take into account for the construction and operation of the generator.
• Specifications drawn up by the EDF / GS21 study committee define the conditions for connecting private energy production units to the public transport network.
• the main rule concerning the electrical sizing of an energy production installation is as follows: - verification of the maximum short-circuit current supplied by the installation at the point of delivery on the network, this verification resulting in the most vast majority of cases of inducing an increase in the reactance of the transformer to reduce the short-circuit current of the installation, - verification of the capacity of the installation to supply to the delivery point, a certain amount of power reactive depending on the voltage conditions (value) at the delivery point.
• This supply constraint is expressed in the document GS21 by a graph on which the reactive power Q exchanged at the delivery point is shown on the abscissa, expressed in proportion to the maximum active power of the installation and officially called Pmax and on the ordinate, the delivery point voltage expressed as a relative value compared to a reference voltage, officially called Vref, the value of which is given by EDF.
• the corresponding net performance [q, u] at the delivery point is a rectangle.
• the graph of net performance [q, u] at the delivery point becomes a trapezoid.
• the increase in the reactance of the transformer is reflected on the graph by an increase in the slope of the trapezoid.
• the invention aims to remedy the aforementioned drawbacks of connecting large machines to the network and to improve the conditions for connecting such machines to the network.
• the voltage is lowered so that the generator can always transform the active power of the available turbine as closely as possible or sized according to site conditions and that the generator can simultaneously deliver reactive power as closely as possible associated
• the generator is adapted to a reduced voltage Ungf in order to reduce the short-circuit current and increase the dynamic range of the regulated voltages at least equal to that of its old range around its old nominal voltage Ungi;
• the generator being oversized and initially designed for operation under a Ungi voltage, its operating voltage Ungf with a reduced short-circuit current is linked to the initial operating voltage Ungi by the relation:
• Ps and Qs being respectively the active power and the reactive power of the site, and Png and Qng being respectively the nominal active power and the nominal reactive power of the generator;
• Fig.1 is an equivalent diagram of a current generator alternative connected to the network
• - Fig.2 is a vector representation of the voltage across the network delivered by the generator with a first reactance value of the link transformer
• - Fig.3 is a vector representation of the voltage across the network, delivered by the generator with a second reactance value of the link transformer
• - Figs.4 and 5 are vector representations of the characteristic quantities of the generator and the network with two different values of the voltage at the delivery point;
• FIG. 6 is a vector representation of the voltage at the delivery point and the generator voltage and their respective slopes illustrating an additional difficulty in connecting the generator to the network.
• Vg2cos ⁇ g2 Vcpcos ⁇ cp
• FIGS. 2 and 3 reproduce the changes in each of the characteristic quantities when the reactance of the transformer is varied by keeping the active power Pcp and the reactive power Qcp delivered to the network constant, which responds to a general constraint imposed by network managers to keep the Qcp / Pcp ratio constant.
• the diagram in FIG. 1 is a vector representation of the different quantities involved in the operation of the system.
• the current I is directed towards the reference axis.
• the voltage across the generator having a first value Vg1 has a phase shift cp g1 relative to the current I.
• the voltage Vcp at the delivery point has a phase shift ⁇ cp with the current I due to the presence of the reactance 1 having a first value X t1 causing a voltage drop X t1 .l.
• the vector sum of the electromotive force of the generator Eg1 and the voltage Xpl due to the Potter reactance of the generator is equal to the voltage Vg1 across the terminals of the generator.
• the vector sum of the voltage Vcp across the network and the voltage Xr.l due to the direct reactance of the network seen at the delivery point is equal to the electromotive force at the delivery point of the network.
• the machine thus provides the same active power but more reactive power.
• Vg1 cos ⁇ g1 Vcp1 cos ⁇ cp
• Vg2cos ⁇ g2 Vcp2cos ⁇ cp
• the new current is lower than the old; the reactive power consumption in the transformer becomes:
• the alternator must therefore supply the same active power; Pcp and a total reactive power Qg2 such that:
• connection conditions show an additional connection condition.
• the resulting discomfort is especially noticeable for the high network voltages which prevent the alternator, itself unable to raise its voltage by more than 10%, to provide all the expected reactive power.
• This slope is not mathematically equal to that of the parallelogram appearing in the usual diagrams of the specifications at delivery point, but still remains fairly well represented by the slope of the parallelogram.
• the slope is defined by the variation of reactive power exchanged at the coupling point as a function of the difference between the voltage at the coupling point and the alternator voltage.
• Vgcos ⁇ g Vcpcos ⁇ cp (8)
• Vgsin ⁇ g Vcpsin ⁇ cp + Xt.l (9)
• Vg.l.sin ⁇ g Vcp.l.sin ⁇ cp + Xt I 2
• Qg Qcp + Qt
• Vcp voltage at the delivery point, which will be assumed to be high in order to be able to assess the absolute voltage of the alternator Vg necessary for virtually maintaining Qcp.
• Vg absolute voltage across the generator
• Xt constant reactance of the transformer
• Qcp reactive power at the delivery point, the variation of which as a function of Vg (slope) must be controlled
• Qg reactive power supplied by the alternator
• Qt reactive power consumed by the reactance of the transformer.
• the “turbine + generator” group is very often slightly oversized from the point of view of active power and almost always oversized from the point of view of reactive power.
• the generator voltage is made by the manufacturer and not by the network manager.
• this same generator is oversized in reactive power.
• the invention consists in evaluating the generator as closely as possible according to the need of the site, by lowering the nominal voltage to the lowest while continuing to satisfy the ability to export the active power delivered by the generator drive device, the power reactive corresponding to this active power required by the consumer or the network operator.
• the lowering of the voltage is ensured so that the alternator can always transform the active power of the drive device available or dimensioned as closely as possible according to site conditions and that the alternator can simultaneously deliver, as accurately as possible, the power associated reactive, defined by the consumer.
• the method used is pessimistic because as the losses to the rotor are reduced in a large proportion because they vary with the square of the excitation current and the f.e.m. demand is lower, as the overall iron losses are slightly reduced due to the f.e.m. reduced, in the caloric balance of the losses to dissipate, one could therefore accept losses of the stator a little higher than the original losses.
• x'd transient reactance (originally subtransient x "d in IEC 909).
• x'd transient reactance (originally subtransient x "d) of the alternator.
• Sin ⁇ ng is deduced from the nominal power factor cos ⁇ ⁇ g of the alternator.
• cmax varies from 1 to 1, 1 according to the type of minimum or maximum short-circuit current that one seeks to establish and according to the quantity of hazards of the network that one seeks to take into account in the result final.

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• Engineering & Computer Science (AREA)
• Power Engineering (AREA)
• Control Of Eletrric Generators (AREA)
• Supply And Distribution Of Alternating Current (AREA)

Applications Claiming Priority (3)

Publications (1)

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ID=8846332

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Country Status (10)

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Citations (1)

Family Cites Families (7)

• 2000
  • 2000-01-26 FR FR0000994A patent/FR2804254B1/fr not_active Expired - Fee Related
  • 2000-07-31 US US09/629,699 patent/US6351103B1/en not_active Expired - Fee Related
• 2001
  • 2001-01-25 WO PCT/FR2001/000242 patent/WO2001056131A1/fr active Application Filing
  • 2001-01-25 EP EP01907701A patent/EP1166422A1/fr not_active Withdrawn
  • 2001-01-25 BR BR0104247-5A patent/BR0104247A/pt not_active Application Discontinuation
  • 2001-01-25 KR KR1020017011997A patent/KR20020004977A/ko not_active Application Discontinuation
  • 2001-01-25 AU AU35604/01A patent/AU3560401A/en not_active Abandoned
  • 2001-01-25 CA CA002365632A patent/CA2365632A1/fr not_active Abandoned
  • 2001-01-25 JP JP2001555178A patent/JP2003521209A/ja active Pending
  • 2001-01-26 AR ARP010100335A patent/AR027930A1/es unknown

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