EP3332467A1

EP3332467A1 - Auxiliary system for storage and supply of electrical energy for multiple uses incorporated in an electricity production plant

Info

Publication number: EP3332467A1
Application number: EP15770558.3A
Authority: EP
Inventors: Hervé Biellmann
Original assignee: GE Energy Products France SNC
Current assignee: GE Energy Products France SNC
Priority date: 2015-08-07
Filing date: 2015-08-07
Publication date: 2018-06-13
Also published as: US20180145511A1; WO2017025664A1; US10243366B2

Abstract

The invention relates to an appended system for supplying electrical energy for an electricity production plant comprising at least one turbine coupled to an alternator forming a main unit (2) for electrical energy production supplying an energy discharge grid (10), itself supplying a main auxiliary grid (4, 15) intended to supply the auxiliary systems (6,16) of the plant. The system comprises a secondary unit for electrical energy supply (7), itself comprising at least one elementary unit (8) for storing and restoring electrical energy in DC form. Said elementary unit comprises electrical energy storage elements (81) coupled to reversible DC-AC conversion means (82), ensuring, on demand, the charging of storage elements (81) by the main auxiliary grid (4) or the discharging of electrical energy stored in the storage elements (81) onto said main auxiliary grid (4).

Description

AUXILIARY MULTI-PURPOSE STORAGE AND POWER SUPPLY SYSTEM INTEGRATED WITH POWER GENERATING PLANT

FIELD OF THE INVENTION

The invention relates to the general field of electric power generation systems. It relates more particularly to

5 installations of the type of power stations

supplying an electricity transmission network.

BACKGROUND OF THE INVENTION - PRIOR ART

Currently, auxiliary equipment of a power station

are supplied from an ancillary auxiliary network derived from the power-removal network of the power station itself connected to the electricity transmission network supplied by the power plant and to the power generation group.

Generally these facilities also include a network of

15 DC backup that is used in case of loss of sources

main energy supplying the auxiliary network.

These facilities also include various devices to provide various network services through the plant. By network service we mean the technical functionalities realized by the power plants

20 electricity generation in order to ensure the proper functioning of the

electricity transmission network to which they are connected, such as the rapid supply of additional electrical energy to meet the demand for primary response that the plant must be able to provide in case of solicitation of the network.

The European patent application published under the reference

EP 2595266 (A1) describes in this connection an installation for producing electrical energy comprising means for generating electrical energy intended to be connected to a distribution network and means for storing part of the electrical energy produced. in the form of energy

30, by means of flywheels, the stored energy being restored

on order at installation in electrical form to provide support functions such as: - Frequency and voltage regulation (steady state and transient);

- the support of micro-cuts of networks;

the guarantee of an optimal state of charge of the storage means in the event of a break;

- the use of stored energy in mechanical form to support the shutdown of the main power generation group and in particular the limitation of the overspeed phenomenon of the alternator shaft;

- support for restarting the plant in the event of a prolonged power failure.

The power generation plant thus described comprises a system for producing electrical energy, generated from kinetic energy stored in flywheels. This system is associated with the main power generation group which supplies electrical power to the electricity distribution network in order to compensate for the inertia of the steam turbine which drives the generator of the main production group. if it is necessary for the plant to provide the primary response requested by the network and, on the other hand, to supply electricity to the auxiliary network of this plant.

This electrical energy production system is managed by a controller controlling the operation of the energy storage means and the connection thereof to the generation means and the electricity transmission network.

The document cited above highlights the advantages of implementing an energy storage system in a plant in order to improve the capacity to provide the primary response, while the latter is in operation. However, it is possible to consider also taking advantage of the features provided by such a system when the plant is stopped and that the electrical energy ceases to be provided by the main group. Indeed, many power plants are now operated cyclically, that is to say that during a given period (season, day, week, ...) they alternate periods operating and shutdown periods. We generally means stopping the periods during which the plant's generating unit does not supply power to the transmission network, the turbine being stopped and the alternator being disconnected from the network or not. As a result, the use during these shutdown periods of the energy storage system would increase the profitability of these plants.

The document cited further describes a system for storing energy in the form of kinetic energy. However, it may be wise to consider other types of energy storage systems. The storage and production of electrical energy by means of electrochemical generators can thus prove to be very competitive, in terms of cost, with respect to storage in the form of mechanical energy, especially when a large autonomy is required. Indeed, energy storage in kinetic form is very suitable for providing high powers for short times (of the order of a minute), but it is less for longer times (of the order of a minute). several minutes to several hours).

But some auxiliaries, commonly called critical auxiliaries, a power plant require to be powered for periods of up to several hours, in case of failure of the normal power source of the auxiliary network of the plant. This is for example the case of shaft line lubrication systems which, in the event of failure of the plant's auxiliary network supply, must be maintained in operation in order to ensure its shutdown and restart in good conditions.

In fact, the power supply of the auxiliaries of a power plant is generally done, as illustrated in FIG. 1, by means of two types of distribution networks:

a main auxiliary network, medium voltage 4 and low voltage 15, of AC type, the main function of this network being to supply, from the energy transmission network 1 or the main power generation group 2, the set of medium voltage auxiliaries 6 and low voltage 16 of the plant necessary for its proper operation. Among these auxiliaries are typically groups of motor pumps, actuators and auxiliary motors operating on average or low voltage, either fixed frequency or frequency variable, the frequency variation can be achieved by means of static frequency converters.

an auxiliary network 17 called "backup", of DC type, the main function of which is to mitigate a failure of the main auxiliary network and to allow a maintenance operation, at least temporarily, critical auxiliaries of the plant in order to ensure the shutdown of the plant and its restart in good conditions.

These critical auxiliaries include the lubrication systems of the main group 2 shaft line, whose AC motors are redundant by DC motors, powered by batteries, to ensure the lubrication of the generator. shaft line and its stop without damage in case of loss of power of the main AC auxiliary network 4, 15. In a conventional manner, the backup network of a power plant is therefore particularly constituted by a or more than one battery and other equipment operating in direct current, such as switchboards, control equipment and motors and actuators. These equipments, supplied with direct current, are coupled to the main auxiliary network 4, 15, by means of electronic circuits for converting alternating current into direct current. In normal operation of the unit, the batteries are recharged from the main auxiliary network 15. In the event of a malfunction, the batteries restore the stored electrical energy to the equipment operating in direct current.

However, the implementation within one and the same plant of two types of auxiliary networks, a main auxiliary network 4, 15 of alternating current and a direct current network 17, induces a complexity of implementation of the auxiliaries and generates problems. significant costs throughout the life cycle of the plant (eg during the design, commissioning and operation phases of the plant). In fact, these two networks are partially redundant and the equipment operating in direct current, which constitutes in particular the emergency equipment of the critical auxiliaries, is less widespread than the equivalent equipment operating with alternating current and, therefore, generally more expensive. In addition, these equipment and the elements which constitute them, are exclusively dedicated to the emergency function in case of failure.

Thus, considering the network architecture of a conventional plant and the operating constraints related to maintaining the integrity of the plant in the event of failure of the main auxiliary network supply 4, 15, there is a real need to develop a support architecture more efficient auxiliaries, including simplifying the implementation of the latter and ensure their continued operation even in case of failure, without necessarily having recourse means for use only in this case .

At the same time, there is a need for an architecture to improve the network services that can be achieved through the plants to make them more competitive, or even expand the range of network services that can be provided.

PRESENTATION OF THE INVENTION

An object of the invention is to improve the capabilities of a power plant in terms of network services and operation while drastically simplifying the architecture of its auxiliary power distribution.

To this end, the subject of the invention is an ancillary system for the supply of electrical energy. An additional system for the supply of electrical energy for an electricity generating station supplying an electric power transmission network, said production plant of electricity comprising at least one turbine coupled to an alternator forming a main power generation group which supplies an alternating current to an energy evacuation network connected to the transmission network, the energy evacuation network also supplying electricity a main auxiliary network, said main auxiliary network for supplying auxiliary equipment necessary for the operation of the plant. The system according to the invention comprises a secondary electrical energy supply unit itself comprising at least one elementary unit for storing and restoring electrical energy in continuous form. Said elemental unit comprises electrical energy storage elements coupled to reversible AC direct current converting means providing, on command, the charge of the storage elements from the electrical energy delivered by the main auxiliary network or the discharge of the electrical energy stored in the storage elements on said main auxiliary network.

According to the invention, the secondary power generation group is sized and designed so that it can:

- provide the power transmission network with an electrical power time profile at least sufficient to provide the requested network service (s), even for network services to be provided when the main group is at a standstill;

or provide the central auxiliary network of the plant with the time profile of power required to supply the critical auxiliaries of the plant in the event of failure of the supply of said main auxiliary network.

-Supply the two previous functions.

According to various arrangements that may be considered alone or in combination with each other, the system according to the invention may have additional features.

Thus, according to a particular provision, the secondary power supply group is sized so as to be able to supply the electricity transmission network with the time profile of electric power making it possible to compensate for the inertia of the gas turbine and / or of the steam turbine during primary response supply requests.

According to another particular arrangement, the secondary power generation group comprises a plurality of elementary units each comprising at least one electrical energy storage element and a reversible AC-DC converter connected to the inputs of the storage element. . The assembly is coupled to the electricity transmission network or the energy evacuation network or the main auxiliary network of the plant. The elementary units are dimensioned to be able to produce when they are put into service simultaneously at least the requested power. According to another particular arrangement, the plant being equipped with a first auxiliary thermal generator and / or a second emergency power generating unit, the secondary electrical power supply unit is dimensioned so as to be able to deliver power to the generator. less equivalent to that of the first auxiliary heat group or that of the second auxiliary heat group or to the sum of the powers of these two groups.

According to another particular provision, the secondary power supply group is dimensioned such that it provides sufficient power to allow itself to start the alternator of the main group, or that, the central being equipped with an auxiliary thermal generator connected, on command, to the main auxiliary network, it provides sufficient power for the addition of the power supplied by the storage means and the power supplied by the auxiliary thermal generator is sufficient to allow the alternator start of the main group.

According to another particular provision, the elementary cell of the secondary electrical energy supply group furthermore comprises complementary means for reversible conversion of direct current to alternating current, coupled to the elements for storing electrical energy. These means are configured and arranged to allow the secondary power supply group to ensure, on command, the power supply of the alternator of the main group in the starting phase of the latter from the voltage available on the main auxiliary network and / or the energy available in the energy storage elements, or the load of the electrical energy storage elements and / or the supply of the main auxiliary electricity supply by withdrawing electrical energy by means of complementary conversion means directly to the terminals of the alternator when it is running.

According to another particular arrangement, the complementary DC reversible conversion means are configured so as to provide, on command, a supply voltage of variable frequency for supplying the engines of auxiliary equipment likely to operate at variable speed.

According to another particular arrangement, the elementary cell of the secondary electric power supply group furthermore comprises an additional additional DC-DC converter, connected in parallel to the complementary DC reversible conversion converting means, and making it possible to supply the alternator rotor of the generating set.

According to another particular arrangement, the complementary means of reversible AC direct current converting means are made from IGBT switches (isolated-gate bipolar transistors) controlled by appropriate means.

According to another particular arrangement, the system according to the invention further comprises control means making it possible to operate each of the reversible conversion means either as an AC-DC converter or as a DC-AC converter delivering a given fixed frequency alternating current or variable frequency.

Moreover, the subject of the invention is also a power generation plant which comprises an auxiliary system for producing electrical energy according to the invention.

The proposed system for storing and restoring electrical energy advantageously makes it possible to design an electricity generation plant comprising means making it possible to:

- provide the network services requested when the plant is in operation;

- also provide certain network services when the plant is shut down;

- to supply the necessary power to supply the alternative critical auxiliaries of the plant in the event of loss of the normal power supply of its main AC auxiliary network. More particularly, by using certain types of electrochemical generators with appropriately specified characteristics, the proposed electrical energy storage and retrieval system can be advantageously configured to provide a certain time profile of primary reserve power and, once this reserve delivered primary, always be able to provide, following the power time profile required to power the critical auxiliaries of the plant for the desired duration. Indeed, the power profile of the primary response requires the provision of a high power only for a few minutes, which does not cause a complete discharge electrochemical generators provided that they are sized for this purpose.

DESCRIPTION OF THE FIGURES The characteristics and advantages of the invention will be better appreciated thanks to the description which follows, a description which is based on the appended figures which present:

FIG. 1 is a block diagram showing the structure of an ancillary network of a plant according to the state of the art with auxiliary auxiliary equipment with direct current, as well as the principle of connection of the continuous power sources and alternatives to the various equipment of the plant;

- Figure 2, a block diagram showing the basic structure of a system according to the invention and its interconnection to the auxiliary circuit of a power plant;

- Figure 3, a block diagram showing the device according to the invention in an alternative embodiment and interconnection allowing it to provide additional functionality. It should be noted that in the different figures, the same structural or functional element is identified by the same numerical or alphanumeric reference.

DETAILED DESCRIPTION Figure 2 shows schematically the principle of implementation of the system according to the invention, in a first embodiment, within the power distribution network of a power plant.

This network typically comprises an energy evacuation network

10 connecting the main power generation group 2 of the power plant, comprising in particular a turbine and an alternator driven by said turbine, to an electricity transmission network 1, via a group transformer 3, and an auxiliary network main medium voltage 4, and low voltage 15, connected to the energy evacuation network 10 via an auxiliary transformer 5, on which are connected the medium voltage auxiliaries 6 and low voltage 16 of the plant, and one or more groups of electricity production annexes.

Auxiliaries 6, 16 are constituted by the equipment necessary for the proper functioning of the plant, both the electrical and electronic management and control units, and the equipment performing tasks essential to the proper functioning of the main electricity generation group, such as for example the lubrication pumps of the main group 2 shaft line.

Among the auxiliary power generating units that a power plant can have, there are in particular auxiliary thermal generators 14 and 11, the functions of which consist respectively of:

for the auxiliary heat unit 14, to feed certain critical auxiliaries of the plant in the event of failure of the main auxiliary network supply 4,15,

- For the auxiliary heat unit 1 1, to provide extra energy to start the plant without power from the transport network 1.

As illustrated in FIG. 2, the ancillary electric power supply system according to the invention mainly comprises a secondary power supply group 7 capable of storing electrical energy taken from the power plant network. which it is integrated and to restore this energy to this same network. For this purpose the secondary group 7 mainly comprises one or more elementary units 8 of electrical power supply configured and arranged to be able to operate in parallel. For reasons of simplicity and clarity of the diagram, FIG. 2 shows a secondary group 7 comprising a single cell 8.

As illustrated in FIG. 2, each elementary unit 8 comprises means 81 for storing electrical energy, constituted for example by electrochemical generators, in other words storage batteries. Since several elementary units can be used in parallel, it is possible to combine several storage means of different technologies in order to optimize the dimensioning and therefore the cost of the secondary group.

Each unit 8 also comprises one or more AC / DC reversible converters 82, each converter being preferably constituted by electronic power switches, of the bipolar transistor type with insulated gate, or IGBT according to the English terminology, whose operation is managed by the control means of the system.

The sizing of the secondary group 7 can be achieved either by sizing the different elements 81 and 82 of an elementary unit 8, or by varying the number of elementary units 8 constituting the secondary group 7 considered.

In a preferred embodiment of the system according to the invention, control means, not shown in FIG. 2, make it possible to operate the converters 82 of the different elementary units 8 either as an AC-DC converter or as a DC converter. -AC delivering an AC current of given fixed frequency or variable frequency.

Each elementary unit 8 is moreover permanently connected, according to the power that it must develop, to the energy transport network 1 or to the energy evacuation network 10 or to the main auxiliary network 4, via a reversible converter 82 of continuous electrical energy into alternative electrical energy (conversion AC-DC and DC-AC conversion) and, if necessary, via a voltage matching transformer 83.

Each elementary unit 8 can also be connected to one or the other of these networks either directly at the converter (or one of the converters) 82, or via an adaptation transformer 83.

According to the invention each elementary unit 8 can be put into service separately via the control means of the system. The cutting into elementary units of the secondary power supply group 7 thus advantageously makes it possible, in the case where the secondary group 7 comprises several elementary units 8, to put into service only the number of elementary units corresponding to the need for inputting. expected energy.

The power dimensioning of the secondary group 7 can thus be achieved either by sizing the different elements 81 and 82 of an elementary unit 8, or by varying the number of elementary units 8 constituting the secondary group 7 considered.

The integration of a power generation plant with an electrical energy storage and return system, such as the system according to the invention, has many advantages, among which may be mentioned:

a) The possibility of designing power generation plants that do not include DC back-up networks or redundant backup auxiliary equipment, operating in direct current, such as those mentioned above, equipment that equips the existing power plants.

Integration with a central unit of the system according to the invention makes it possible, by means of the control means of the system, to configure a secondary power supply group 7 to provide an auxiliary power supply. alternatively, in case of failure of the energy evacuation network 10, to supply, via the main auxiliary network 4, 15 and for a predetermined duration, auxiliaries 6 and 16 operating as alternating current. b) The possibility of upgrading existing plants so as to improve the network services they provide and thus increase their profitability, by integrating the system according to the invention into the plant.

(c) The possibility of improving and increasing network services provided by the plant, including by:

- better regulation of frequency and voltage (steady state and transient), this regulation passing through:

- network support for maintaining the transmission network frequency by providing active power (primary response, secondary response, and improving the stability of the alternator in the event of a network voltage dip or "FRT recovery" according to the Anglo-Saxon name, ...),

network support for maintaining the voltage of the transmission network by supplying reactive power,

- a contribution, as part of a procedure to restart the plant on "dead busbar", that is to say without supply of auxiliary power from the transport network, procedure called "black-start" According to the Anglo-Saxon name,

d) Strengthening the reliability and robustness of the plant in response to voltage dips.

e) The possibility of reducing maintenance costs of the plant by eliminating continuous equipment (switchboards and electrical equipment, motors, etc.).

f) The possibility of having a modular auxiliary power supply and configurable thanks to the modular structure of the system according to the invention, modularity that also gives the system a better reliability and greater robustness.

In this respect, the secondary power supply group 7 can be sized to provide the power time profile corresponding to the required network service and the power time profile required to supply the critical auxiliaries and to enable, at least temporarily, their power supply. maintenance in operation, so as to ensure the shutdown of the plant and its restart in good conditions. Thus, in the event of loss of the power supply of the main auxiliary network, the control system of the storage system can control, by means of appropriate interfaces with the control system of said network, the power supply of the critical auxiliaries of the plant since energy storage elements. This characteristic of the system therefore makes it possible to drastically simplify the architecture of the auxiliary electrical distribution of the control unit by eliminating the auxiliary backup network 17, since it provides the same functionalities.

Thus the secondary group 7 may, for example, be sized to be able to deliver instantly to the electricity transmission network 1 an electric power at least equal to the additional power to be provided by the steam turbine of the main group 2 in case of primary response request. In this way, the inertia of the steam turbine is compensated by the speed of the response of the secondary group 7 and the main group 2 can thus operate continuously at a higher power.

It will be noted that the primary response corresponds to the fraction of the nominal power of the main group 2 that it must be able to deliver to the network in a very short time. There is no technical requirement common to all networks because each network operator is free to define its own requirements, for example we can consider a power of the order of 2.5% of the nominal power of the group to deliver in a time of the order of 30 seconds.

Moreover, insofar as the plant in question is equipped with an auxiliary thermal generator 1 1 providing a "black-start" function, the secondary group 7 can be sized to be able to deliver, in addition to the required power time profile. for supplying the critical auxiliaries, a power at least equivalent to that of the auxiliary heat unit 1 1.

Such a dimensioning then makes it possible advantageously to use this thermal group in order to provide network services, such as, for example, the primary response. Indeed it is possible, by means of the control system of the storage system, to quickly control the discharge of the storage elements in order to quickly provide on the auxiliary network of the plant a power equivalent to that of the black-start group 1 1, and to control the startup of it so that it replaces the storage system after its startup sequence completed.

Such a principle can also be implemented to perform network services by means of the backup thermal generator 14, and / or to ensure uninterrupted power supply of the loads supplied by this backup group in the event of a failure of the network supply. main assistant. The modular structure of the secondary power supply group 7, associated with the use of reversible DC conversion means 82, configurable by means of the control means of which the system according to the invention is provided makes it possible to advantageously to simplify the composition and organization of ancillary means which a power plant may need in different circumstances. This also makes it possible to have a reconfigurable architecture making it possible to use the secondary group 7 of the system according to the invention, to perform various tasks ordinarily performed by other ancillary equipment which, as a result, can be deleted, or contribute to the execution of these same tasks in association with the other available ancillary means.

Thus, the system for producing additional electrical energy according to the invention can be implemented to provide certain network services when the plant is at a standstill. Indeed, the block diagram described in FIG. 2 shows that it is possible to connect the system to the electricity transmission network 1, through the group transformer 3 and the auxiliary transformer 5, so that it delivers to the transmission network the electrical energy stored in the batteries 81 of the cells 8 constituting the secondary group 7. If necessary, the control system of this system can be interfaced directly with the control system of the transport network 1, and / or with the control system of the main group 2 to control the control and protection devices such as the group circuit breaker 22 or the line circuit breaker 23. Thus also, the system for producing additional electrical energy according to the invention can be implemented so as to be able to provide the power demand required when starting the auxiliary motors 12, so that the thermal group of 14 (diesel group) is only dimensioned according to the permanent power of the auxiliary engines.

Furthermore, the electrical energy production system annexed according to the invention can thus be implemented so as to deliver a variable frequency alternating current for restarting the auxiliary motors 12 progressively, variable frequency, to reduce the current draw during a start on dead bus set, that is to say when no more voltage is present on the main auxiliary auxiliary network 4, 15.

This functionality can be achieved simply by means of interface signals between the system control system and the control system of said main auxiliary network, or if necessary by adding an auxiliary board dedicated to this auxiliary helper restart function on a busbar. death.

Figure 3 shows schematically the principle of implementation of a variant of the system according to the invention within the power distribution network of a power plant.

This embodiment variant differs from that of FIG. 2 in that the secondary power supply group 7 comprises one or more elementary units 8b each comprising one or more reversible converters 84 for continuous electrical energy in alternative electrical energy ( AC-DC conversion and DC-AC conversion).

The second converter 84 is connected to the means 81 for storing electrical energy on the one hand and the alternator of the main group 2 and / or an auxiliary motor 12 'on the other hand.

As in the previous embodiment, the secondary group 7 of the system according to the invention can be connected, depending on its power, either directly to the secondary of the transformer group 3, or to the secondary of the auxiliary transformer 4, which is still the primary of the transformer of group 3.

Similarly, as in the previous embodiment, the secondary power supply group 7 is sized to perform the required network service or services and so that it replaces the DC backup network by filling the corresponding function.

In the embodiment of FIG. 3, the additional electrical energy production system according to the invention can also advantageously be implemented to perform functions normally supported by auxiliary equipment normally present in a power plant and to substitute totally or partially for these equipments. To do this, it is necessary to size the power equipment constituting the system (transformer 83, converters 82 and 84 and storage means 81) so that they can provide at least the power corresponding to the required network service and to the new function. during the necessary time, and to configure the elements constituting the secondary group 7 of the system according to the invention with the aid of the control means which control in particular the mode of operation of the static power converters 82 and 84.

As in the previous embodiment, the control system of this power generation system can be interfaced, if necessary, with the control system of the transport network 1, the control system of the main group 2 and the control system of the control system. auxiliary distribution network 4.15 to control the operation of the various control devices (circuit breakers, etc.) and to perform the functions required of the secondary group 7.

Thus, for example, the system according to the invention can be implemented, by using the static power converters 82 and 84 which equip each cell 8 of the secondary group 7, to ensure the static start of the shaft line when the central station is stationary and is not used for another function.

The static start of the shaft line is usually done using a static frequency converter used to power the alternator in motor mode so as to rotate the shaft line of the gas turbine during its startup phase.

To achieve this start using the system according to the invention the converter 82 is driven rectifier (that is to say in voltage source) to create, from the voltage present on the auxiliary network of the central 4 , a DC voltage on the internal DC bus of the secondary group 7. The converter 84 is then driven by UPS in such a way that it converts the DC voltage supplied by the converter 82 into a variable frequency AC voltage.

This configuration of the system according to the invention thus makes it possible to drastically simplify the architecture of the accessories of the central unit by eliminating the static power conversion system 19 (see FIG. 1) normally dedicated to the start of the shaft line. Similarly, the auxiliary electric power generation system according to the invention can advantageously be implemented, so as to ensure the turning function of the shaft line. To do this, the converter 84 is driven in an inverter so as to provide the power necessary for the rotation at very low speed of the shaft line, when the control unit is at a standstill.

This configuration of the system according to the invention thus makes it possible to perform the turning function by feeding the turning motor by means of the energy available on the auxiliary network and / or the energy stored in the storage means of the system, allowing and to advantageously simplify the architecture of the auxiliaries of the plant.

In the same embodiment, the electrical energy production system of the invention may also advantageously be implemented, so as to provide all or part of the power required to start the line. shaft using electrochemical generators 81. To do this, the electrical energy stored in the DC voltage generators (ie the batteries) 81 is converted into alternating current by the converters 82 and 84 and transferred to the alternator in motor mode so as to drive the line of rotation in rotation. shaft of the gas turbine. This configuration of the system according to the invention thus makes it possible to advantageously simplify the architecture of the auxiliaries of the central unit by making it possible to eliminate the auxiliary thermal unit 1 1 necessary for the start-up of the central unit on a dead busbar (that is to say when the plant must restart without power from the distribution network), or at least reduce the power of this group and therefore its cost by providing a portion of the power required by the storage elements 81. Likewise, the system for producing additional electrical energy according to the invention may advantageously be implemented, so that the static power converter 84, (to the extent that it is not used as described previously in FIG. of the start-up phase of the plant), can be used to supply a variable frequency auxiliary motor.

This configuration of the system thus makes it possible to advantageously simplify the architecture of the accessories of the control unit by eliminating a static frequency converter dedicated to supplying one or more variable speed auxiliary motors 12, such as for example a food pump motor. the boiler in a combined cycle plant.

Furthermore, the additional electric power generation system according to the invention can also be advantageously implemented, so as to temporarily provide the power required to supply the static converter 84 by means of the electrochemical generators 81.

This configuration of the system according to the invention thus makes it possible to provide a supply without disturbances (such as for example voltage dips) of the motor driven by means of the converter 84, even when the main auxiliary network of the plant is disturbed.

Moreover, the system according to the invention can also be advantageously implemented, so that it allows to draw electrical energy from the alternator to charge the storage means 81 and / or replenish the main auxiliary network 4 of the plant by means of the converters 82 and 84 of this system in the event of failure of the supply of said main auxiliary network 4.

To do this, it is necessary to drive the converter 84 rectifier (that is to say, voltage source) to create and regulate, from the alternating voltage generated by the alternator, a DC voltage on the bus internal continuous secondary group 7 storage system. The converter 82 is in turn controlled by the inverter, so that it converts the DC voltage supplied by the converter 84 into a fixed frequency AC voltage.

This configuration of the system according to the invention thus makes it possible to drastically simplify the architecture of the auxiliaries of the plant by eliminating the backup auxiliary heat group 14, or to increase the reliability of the supply of the main auxiliary network of the plant by means of of this additional voltage source. In fact, in the event of incidents on the electric power transmission network 1, the plant is able to isolate itself from said network by means of the line circuit breaker 23, and to supply its auxiliaries while maintaining the main group 2 in operation.

Moreover, in this same embodiment, the electrical energy production system annexed according to the invention can advantageously be implemented, in such a way that it makes it possible to extract electrical energy from the alternator of the generator. main group 2, in order to replenish the main auxiliary network 4 of the plant by means of the converters 82 and 84 of this system in the event of failure of the energy storage elements 81.

This configuration of the system according to the invention thus makes it possible to increase the reliability of the secondary power unit 7 in the event of failure of the energy storage elements 81, the power necessary to ensure the supply of the main auxiliary network 4 being in this case provided by the alternator.

Moreover, finally, in this same embodiment, the electrical energy production system annexed according to the invention can be advantageously dimensioned and designed, so that it can supply the excitation system of the alternator of the main group 2 by means of an additional DC / DC converter connected in parallel with the converter 84.

This configuration of the system according to the invention thus makes it possible to supply the stator as well as the rotor of the alternator so that it is possible to start the shaft line by means of the single production system, starting from the energy available in the storage elements 81 and / or on the main auxiliary network 4.

It should also be noted that the installation of the system according to the invention advantageously makes it possible to ensure the operation of critical auxiliaries operating in direct current that may need to be maintained, in particular in the case where the system according to the invention invention is implemented in the context of a discount operation to an existing plant. These DC equipment, according to their quantity, can be connected directly by means of their control / protection equipment to the secondary group 7 of the system at the output of the energy storage elements 81, or at the output of the secondary group 7 by means of an additional DC converter.

Claims

1. Auxiliary electrical power supply system for an electricity generation plant supplying an electricity transmission network (1), said power generation plant comprising at least one turbine coupled to an alternator forming a main group ( 2) producing electrical energy which supplies an alternating current to an energy evacuation network (10) connected to the transport network (1), the energy evacuation network (10) also supplying an auxiliary network main (4, 15), said main auxiliary network for supplying the auxiliary equipment (6, 16) necessary for the operation of the plant, characterized in that said system comprises a secondary power supply group (7) comprising itself at least one elementary unit (8) for storing and restoring electrical energy in continuous form, said elementary unit comprising elements Electrical energy storage means (81) coupled to a reversible AC direct current converting means (82) providing, on command, charging of the storage elements (81) from the electrical energy delivered by the network main auxiliary (4) or the discharge of the electrical energy stored in the storage elements (81) on said main auxiliary network (4), the secondary power generation group (7) being sized and designed to to be able to provide the electricity transmission network (1) with an electrical power time profile at least sufficient to provide the requested network service or services, even for network services to be provided when the main group is at a standstill and / or so as to be able to supply the main auxiliary network of the power plant (4,15) with the power time profile required to power the critical auxiliaries of the power plant. s of failure of the supply of said main auxiliary network.

2. Ancillary electric power supply system according to claim 1, characterized in that the secondary group of supply of electrical energy (7) is dimensioned so as to provide the electricity transmission network (1) with the time profile of electric power making it possible to compensate for the inertia of the gas turbine and / or the steam turbine when requesting primary response provision.

3. Annex system for supplying electrical energy according to one of claims 1 or 2, characterized in that the secondary power generation group (7) comprises a plurality of elementary units (8) each comprising at least an electrical energy storage element (81) and a reversible AC-DC converter (82) connected to the inputs of the storage element (81), the assembly being coupled to the electricity transmission network (1) or to the energy evacuation network (10) or to the main auxiliary network (4) of the plant, the elementary units (8) being dimensioned so as to be able to produce, when they are put into service simultaneously, at least the requested power.

4. System according to any one of the preceding claims, characterized in that, the central being equipped with a first auxiliary thermal generator (1 1) and / or a second auxiliary thermal generator (14), the secondary group electrical power supply (7) is further dimensioned so as to deliver a power at least equivalent to that of the first auxiliary heat group (1 1) or that of the second auxiliary heat group (14) or the sum of the powers of these two groups.

5. System according to any one of the preceding claims, characterized in that the secondary power supply group (7) is dimensioned in such a way that it provides sufficient power to allow itself the start of the alternator of the main group (2), or that, the plant being equipped with an auxiliary thermal generator (1 1) connected, on command, to the main auxiliary network (4), it shall provide a sufficient power that the addition of the power supplied by the storage means (81) and the power supplied by the auxiliary thermal generator (1 1) is sufficient to allow the alternator of the main group (2) to start.

6. System according to any one of the preceding claims, characterized in that the elementary cell (8b) of the secondary power supply group (7) further comprises complementary means (84) of reversible conversion of direct current into alternating current, coupled to the electrical energy storage elements (81) and enabling the secondary electrical power supply unit (7) to supply, on command, the alternator supply of the main group (2) in starting phase of the latter from the voltage available on the main auxiliary network (4) and / or the energy available in the energy storage elements (81), or the load of the storage elements (81) of electric energy and / or supplying the main auxiliary electricity supply (4) by withdrawing electrical energy by means of the complementary conversion means (84) directly at the terminals of the alternator when this one is running.

7. System according to claim 6, characterized in that the complementary means (84) of reversible conversion of direct current to alternating current are configured to provide, on command, a variable frequency supply voltage for powering the motors. auxiliary equipment (12) capable of operating at variable speed.

8. System according to one of claims 6 or 7, characterized in that the elementary cell (8b) of the secondary power supply group (7) further comprises an additional DC / DC converter connected in parallel with the converter ( 84) for supplying the rotor of the alternator of the generating unit 2.

9. System according to any one of the preceding claims, characterized in that the means (82, 84) for reversible conversion of direct current to alternating current, are made from IGBT switches (bipolar transistors with isolated gates) controlled by appropriate means.

10. System according to any one of the preceding claims characterized in that it further comprises control means for operating each of the reversible conversion means (82, 84) either AC-DC converter or DC-DC converter. AC delivering an AC current of given fixed frequency or variable frequency.

1 1. Power generation plant, characterized in that it comprises an ancillary system for generating electrical energy according to any one of the preceding claims.