EP2411745B1 - System for cryogenic cooling for consumer cooling with temporally variable load - Google Patents
System for cryogenic cooling for consumer cooling with temporally variable load Download PDFInfo
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- EP2411745B1 EP2411745B1 EP10712464.6A EP10712464A EP2411745B1 EP 2411745 B1 EP2411745 B1 EP 2411745B1 EP 10712464 A EP10712464 A EP 10712464A EP 2411745 B1 EP2411745 B1 EP 2411745B1
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- gas
- valves
- consumer
- delivery
- regulator
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
- F25B—REFRIGERATION MACHINES, PLANTS OR SYSTEMS; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS
- F25B9/00—Compression machines, plants or systems, in which the refrigerant is air or other gas of low boiling point
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
- F25B—REFRIGERATION MACHINES, PLANTS OR SYSTEMS; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS
- F25B49/00—Arrangement or mounting of control or safety devices
- F25B49/02—Arrangement or mounting of control or safety devices for compression type machines, plants or systems
Definitions
- the invention relates to a cryogenic system for cooling a consumer having a variable thermal load over time; it applies in particular to the cooling of superconducting magnets.
- a cryogenic system for cooling a consumer generally comprises a fluid circuit in which pressurized heat transfer gas (N 2 or He) flows from a compression stage to a "cold box", where it is cooled and partially liquefied by relaxation.
- the cold box contains a bath of liquefied gas, in thermal contact with the consumer to cool.
- the heat transferred by the consumer to the bath (“heat load”) causes the evaporation of a portion of the gas, which is removed from the cold box to the compression stage, so as to close the circuit.
- a system of this type is particularly suitable for cooling a consumer having a constant or slowly variable heat load, but is not very effective when the thermal load varies significantly on a time scale of the order of minutes, even seconds. Such conditions are encountered especially during the cooling of the superconducting magnets, and in particular magnets used in research tokamaks on controlled nuclear fusion.
- the document FR 2 919 713 describes a method and a cryogenic installation according to the preamble of claim 1, particularly suitable for cooling consumers with a variable thermal load over time.
- the solution proposed by this document is to provide, in the cold section of the instalation, a liquefied gas accumulator. This accumulator makes it possible to store cold fluid when the value of the thermal load is low, and to supply it to the consumer when the heat load increases.
- the accumulator thus behaves like a filter that decouples the variability of the thermal load of the cryogenic circuit, which can continue to operate at constant speed and be sized on the basis of the average thermal load - and no peak - of the consumer.
- the invention aims to provide a cryogenic system for cooling a consumer having a variable thermal load over time, not having the aforementioned drawbacks of the prior art.
- An idea underlying the invention is to modify the system so as to allow operation of the cryogenic circuit in dynamic mode, instead of circumventing the problem by "filtering" the variability of the thermal load by a cold fluid accumulator.
- a cryogenic system of conventional type can work satisfactorily in dynamic mode, provided to be provided with a suitable control means.
- the inventors have understood that the adaptation of a conventional cryogenic system to a variable load can be achieved by means of automatic techniques, without the need for significantly modify its material structure, and in particular that of its cold part.
- the adaptation of an existing installation can therefore be carried out at a limited cost, and the design of installations specifically dedicated to consumers with variable thermal load is greatly simplified.
- An object of the invention is therefore a cryogenic system for cooling a consumer having a variable thermal load over time, comprising: a cold box in thermal contact with said consumer, supplied with compressed heat transfer gas by a supply duct and connected to a discharge pipe for discharging said gas at a lower pressure; and a pressure control assembly in said supply and discharge conduits having a plurality of controlled valves and a control device for controlling the opening of said valves; characterized in that said control device is a multivariable controller adapted to generate opening control signals of said valves as a function of measured values and pressure setpoints in said supply and discharge conduits on the basis of a mathematical model of the system taking into account a coupling between the pressure values in the supply and discharge pipes via said cold box.
- the Figure 1A illustrates, in a simplified way, the structure and operation of a conventional type CRY helium-liquefied refrigerator-liquefier.
- Such an installation comprises a cryogenic circuit comprising a high pressure line CHP, a low pressure line CBP, a compression stage CMP and a cold box BF.
- the compression stage CMP may comprise one or more compressors, for example of the screw type, as well as an unrepresented deoiler.
- the gas - Helium in particular - compressed by the compression stage flows in the high pressure line, or supply line CHP, at a pressure P HP of the order of 15 -20 bar, in the direction of the cold box BF; the mass flow rate of the compressor, assumed to be constant, is indicated by Q CMP .
- the flow of heat transfer gas (Helium) is subdivided in two: a flow rate Q JT passes through a Joule-Thomson V JT expansion valve (after a possible pre-cooling with liquid nitrogen , not shown), while the remaining flow passes through an expansion turbine TD.
- a flow rate Q JT passes through a Joule-Thomson V JT expansion valve (after a possible pre-cooling with liquid nitrogen , not shown), while the remaining flow passes through an expansion turbine TD.
- the gas cooled by its passage through the turbine TD is injected into countercurrent exchangers and used to pre-cool the flow through the Joute-Thomson valve, upstream. of the latter, according to the principle of Claude's cycle.
- the Q V JT / Q L JT ratio depends in particular on the upstream temperature of the expansion valve.
- a consumer CONS represented by an electrical resistance, is in thermal communication with the bath BT.
- This consumer dissipates in the form of heat a power ⁇ ("thermal load") which causes the evaporation of a flow rate Q W of liquid gas.
- This flow rate Q W as well as the flow rate Q V JT and the flow rate passing through the expansion turbine, are discharged from the cold box via the low pressure discharge pipe CBP (P BP of the order of 1.05 bar) towards the CMP compressor.
- a gas storage tank RS at a pressure P RS , intermediate between P BP and P HP (for example, of the order of 9 bar) is connected to the low pressure pipe CBP via a first valve controlled VC 1 , and to the high-pressure pipe CHP via a second valve VC 2 controlled.
- first valve VC 1 When the first valve VC 1 is open, a flow rate Q VC1 of gas is injected into the installation from the reserve RS; conversely, when the second valve VC 2 is open, a flow rate Q VC2 of gas is removed from the installation to be stored in the reserve RS.
- Both valves VC 1 , VC 2 must never be opened at the same time.
- a third valve VC 3 controls the operating point of the installation by opening and closing a bypass path of the cold box, crossed by a flow rate Q VC3 gas.
- Valves VC 1 . VC 2 and VC 3 are controlled by two independent regulators, generally of the PID type (proportional - integral - derivative) to maintain the pressure values P BP and P HP close to respective reference values P 0 BP and P 0 HP .
- PID type proportional - integral - derivative
- a first regulator PID1 generates a control signal SC 3 of the valve VC 3 as a function of the difference P BP - P 0 BP in order to regulate the pressure in the discharge pipe CBP.
- a second regulator PID2 generates a control signal SC 12 of the valves VC 1 and VC 2 as a function of the difference P HP -P 0 HP in order to regulate the pressure in the supply duct CHP.
- the optimal control (that is to say, which minimizes the cost function) can be obtained by solving an algebraic equation of Riccati.
- this problem can be solved by applying a technique known as "control switching".
- the system to be controlled is modeled by a plurality of independent subsystems, each with its own controller, of which the actual system "switches".
- the cryogenic plant SYS can be modeled using two partial models describing the operation of the plant in material supply and withdrawal respectively.
- two vector control signals are generated, one for each partial model; a control selector chooses which of these control signals must be effectively applied to the installation.
- the partial models are linearized around the point of operation of the installation, which can not be done for a "global" model that is supposed to account for the behavior of the system in both regimes at the same time.
- a regulator embodying the principles of the invention will be described in more detail with reference to the figure 2 .
- the pressure values P HP and P BP measured in the CHP and CBP ducts respectively, are input to a mathematical model MOD of the CRY installation, consisting of two submodels or partial models MP 1 , MP 2 , representing the operation of the installation in terms of intake and removal of material respectively.
- These models make it possible to associate with the temporal variations of the pressures P HP and P BP "virtual" variations of opening of the valves CV 1 , CV 2 .
- the partial models make it possible to calculate "virtual openings" O V 1 .
- O V 2 of said valves which, if real, would produce the observed pressure fluctuations (which, in reality, are generated mainly by thermal load variations, not measured directly).
- the first DC regulator 1 is intended to control the CRY cryogenic installation in material supply regime: to do this, it generates control signals (or a first vector signal of control) SC 1 and SC ' 3 for controlling the valves CV 1 and CV 3 respectively. On the other hand, this regulator does not act on the valve CV 2 which, in material supply regime, is supposed to remain in the closed state.
- the second DC 2 regulator is intended to control the CRY cryogenic installation in material removal regime: to do this, it generates control signals (or a second vector control signal) SC 2 and SC " 3 intended to control the valves CV 2 and CV 3 respectively. for against, this controller does not act on the valve CV 1 which, on the withdrawal system, is expected to remain in the closed state.
- Non-linear DC 1 , DC 2 controllers could also be used, providing only physically feasible opening signals; in this case, the control selection would be by identifying which of the signals SC 1 and SC 2 is closest to zero.
- the linearized equations also make it possible to calculate the "virtual openings" O V 1 , O V 2 as a function of the pressures P BP , P HP measured.
- FIG. Figures 3A - 3C compare the behavior of a system according to the invention with a system of the prior art, of the type shown in FIG. Figure 1A .
- the heat transfer gas is helium, and the thermal bath B is at a temperature of 4.2 K.
- Tests were carried out by sending to a consumer (electrical resistance) power pulses of 300W of rectangular shape, lasting 50 s and with a period of 100 s.
- Curves ⁇ INV and ⁇ REF on the figure 3A show the corresponding thermal loads, the variation of which is damped by the thermal inertia of the consumer.
- the exponent “INV” indicates the measurements relating to the system of the invention, while “REF” denotes the reference measurements, made on the conventional system.
- FIGS. 4A - 4C show the curves ⁇ INV , P INV BP and P INV HP for a test using slots of thermal power of 1000 W. Under these conditions, the system of the prior art stops working (the compressor stops), whereas in the system of invention the pressure fluctuations are maintained at acceptable levels.
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- Engineering & Computer Science (AREA)
- Physics & Mathematics (AREA)
- Mechanical Engineering (AREA)
- Thermal Sciences (AREA)
- General Engineering & Computer Science (AREA)
- Pipeline Systems (AREA)
- Filling Or Discharging Of Gas Storage Vessels (AREA)
- Containers, Films, And Cooling For Superconductive Devices (AREA)
- Feedback Control In General (AREA)
Description
L'invention porte sur un système cryogénique pour le refroidissement d'un consommateur présentant une charge thermique variable dans le temps ; elle s'applique notamment au refroidissement des aimants supraconducteurs.The invention relates to a cryogenic system for cooling a consumer having a variable thermal load over time; it applies in particular to the cooling of superconducting magnets.
Un système cryogénique pour le refroidissement d'un consommateur comporte généralement un circuit fluidique dans lequel du gaz caloporteur sous pression (N2 ou He) circule d'un étage de compression à une « boîte froide », où il est refroidit et partiellement liquéfié par détente. La boîte froide contient un bain de gaz liquéfié, en contact thermique avec le consommateur à refroidir. La chaleur cédée par le consommateur au bain (« charge thermique ») provoque l'évaporation d'une partie du gaz, qui est évacué de la boîte froide vers l'étage de compression, de manière à boucler le circuit. Un tel système est décrit, par exemple, dans l'article de
Un système de ce type convient particulièrement pour le refroidissement d'un consommateur présentant une charge thermique constante ou lentement variable, mais s'avère peu efficace lorsque la charge thermique varie d'une manière importante sur une échelle temporelle de l'ordre des minutes, voire des secondes. De telles conditions se rencontrent notamment lors du refroidissement des aimants supraconducteurs, et en particulier des aimants utilisés dans les tokamaks de recherche sur la fusion nucléaire contrôlée.A system of this type is particularly suitable for cooling a consumer having a constant or slowly variable heat load, but is not very effective when the thermal load varies significantly on a time scale of the order of minutes, even seconds. Such conditions are encountered especially during the cooling of the superconducting magnets, and in particular magnets used in research tokamaks on controlled nuclear fusion.
La manière conventionnelle de gérer le refroidissement des consommateurs présentant des charges thermiques variables, par exemple pulsées, consiste à surdimensionner le système cryogénique sans modifier sensiblement son architecture. Une telle solution est peu satisfaisante du point de vue économique.The conventional way of managing the cooling of consumers having variable thermal loads, for example pulsed, is to oversize the cryogenic system without modifying substantially its architecture. Such a solution is unsatisfactory from the economic point of view.
Le document
L'accumulateur se comporte ainsi comme un filtre qui découple la variabilité de la charge thermique du circuit cryogénique, qui peut continuer à fonctionner à régime constant et être dimensionné sur la base de la charge thermique moyenne - et pas de pic - du consommateur.The accumulator thus behaves like a filter that decouples the variability of the thermal load of the cryogenic circuit, which can continue to operate at constant speed and be sized on the basis of the average thermal load - and no peak - of the consumer.
L'inconvénient de cette solution est qu'elle comporte une augmentation significative du volume et de la complexité de la région froide de l'installation, ce qui a des répercussions défavorables sur son encombrement et son coût.The disadvantage of this solution is that it involves a significant increase in the volume and complexity of the cold region of the installation, which has adverse repercussions on its size and cost.
L'invention vise à procurer un système cryogénique pour le refroidissement d'un consommateur présentant une charge thermique variable dans le temps, ne présentant pas les inconvénients précités de l'art antérieur.The invention aims to provide a cryogenic system for cooling a consumer having a variable thermal load over time, not having the aforementioned drawbacks of the prior art.
Une idée à la base de l'invention consiste à modifier le système de manière à permettre un fonctionnement du circuit cryogénique en régime dynamique, au lieu de contourner le problème en « filtrant » la variabilité de la charge thermique par un accumulateur de fluide froid.An idea underlying the invention is to modify the system so as to allow operation of the cryogenic circuit in dynamic mode, instead of circumventing the problem by "filtering" the variability of the thermal load by a cold fluid accumulator.
En outre, les inventeurs se sont rendus compte du fait qu'un système cryogénique de type conventionnel peut fonctionner de manière satisfaisante en régime dynamique, à condition d'être pourvu d'un moyen de régulation adapté. Autrement dit, les inventeurs ont compris que l'adaptation d'un système cryogénique conventionnel à une charge variable peut être obtenue grâce à des techniques relevant de l'automatique, sans besoin de modifier de manière significative sa structure matérielle, et en particulier celle de sa partie froide. L'adaptation d'une installation existante peut donc être réalisée à un coût limité, et la conception d'installations spécifiquement dédiées à des consommateurs à charge thermique variable se trouve fortement simplifiée.In addition, the inventors have realized that a cryogenic system of conventional type can work satisfactorily in dynamic mode, provided to be provided with a suitable control means. In other words, the inventors have understood that the adaptation of a conventional cryogenic system to a variable load can be achieved by means of automatic techniques, without the need for significantly modify its material structure, and in particular that of its cold part. The adaptation of an existing installation can therefore be carried out at a limited cost, and the design of installations specifically dedicated to consumers with variable thermal load is greatly simplified.
Un objet de l'invention est donc un système cryogénique pour le refroidissement d'un consommateur présentant une charge thermique variable dans le temps, comprenant : une boîte froide en contact thermique avec ledit consommateur, alimentée en gaz caloporteur comprimé par un conduit d'amenée et reliée à un conduit de refoulement pour évacuer ledit gaz à une pression plus faible ; et un ensemble de régulation des pressions dans lesdits conduits d'amenée et de refoulement comportant une pluralité de vannes commandées et un dispositif de commande pour piloter l'ouverture desdites vannes ; caractérisé en ce que ledit dispositif de commande est un régulateur multivariable adapté pour générer des signaux de commande d'ouverture desdites vannes en fonction de valeurs mesurées et de valeurs de consigne des pressions dans lesdits conduits d'amenée et de refoulement sur la base d'un modèle mathématique du système prenant en compte un couplage entre les valeurs de pression dans les conduites d'amenée et de refoulement par l'intermédiaire de ladite boîte froide.An object of the invention is therefore a cryogenic system for cooling a consumer having a variable thermal load over time, comprising: a cold box in thermal contact with said consumer, supplied with compressed heat transfer gas by a supply duct and connected to a discharge pipe for discharging said gas at a lower pressure; and a pressure control assembly in said supply and discharge conduits having a plurality of controlled valves and a control device for controlling the opening of said valves; characterized in that said control device is a multivariable controller adapted to generate opening control signals of said valves as a function of measured values and pressure setpoints in said supply and discharge conduits on the basis of a mathematical model of the system taking into account a coupling between the pressure values in the supply and discharge pipes via said cold box.
Selon des modes de réalisation particuliers de l'invention :
- Ledit dispositif de commande peut comporter : un premier régulateur pour générer un premier signal de pilotage desdites vannes sur la base d'un premier modèle partiel du système ; un deuxième régulateur pour générer un deuxième signal de pilotage desdites vannes sur la base d'un deuxième modèle partiel du système, différent dudit premier modèle partiel ; et un sélecteur de commande pour appliquer sélectivement auxdites vannes le premier ou le deuxième signal de commande.
- Ledit système de régulation peut comprendre : une réserve de stockage de gaz caloporteur à une pression intermédiaire entre celle dudit conduit d'amenée et celle dudit conduit de refoulement ; une première vanne commandée, disposée entre ladite réserve de stockage et ledit conduit de refoulement, pour permettre une injection de gaz dans ce dernier à partir de ladite réserve ; une deuxième vanne commandée, disposée entre ladite réserve de stockage et ledit conduit d'amenée, pour permettre une évacuation de gaz depuis ce dernier vers ladite réserve ; et une troisième vanne commandée, disposée entre ledit conduit d'amenée et ledit conduit de refoulement, pour permettre un contournement de la boîte froide.
- Ledit premier régulateur peut être adapté pour générer un premier signal de commande d'ouverture de la première et de la troisième vanne, à l'exclusion de ladite deuxième vanne, sur la base dudit premier modèle partiel du système ; et ledit deuxième régulateur peut être adapté pour générer un deuxième signal de commande d'ouverture de la deuxième et de la troisième vanne, à l'exclusion de ladite première vanne, sur la base dudit deuxième modèle partiel du système.
- Ledit premier modèle partiel peut modéliser le comportement du système lorsqu'un volume de gaz est injecté dans le conduit de refoulement, et ledit deuxième modèle partiel peut modéliser le comportement du système lorsqu'un volume de gaz est extrait du conduit d'amenée.
- Ledit modèle mathématique du système peut modéliser des perturbations de débit du gaz caloporteur induites par des variations temporelles de la charge thermique d'un consommateur en communication thermique avec ladite boîte froide par des variations virtuelles des ouvertures des vannes du système de régulation, ces dernières étant fournies audit dispositif de commande en tant que variables d'entrée à côté des valeurs mesurées et de consigne des pressions
- Ledit dispositif de commande peut être adapté pour minimiser une fonction de coût dépendant des écarts entre les pressions mesurées dans les conduites d'amenée et de refoulement et les valeurs de consigne respectives, ainsi que de l'amplitude des signaux de commande générés. En particulier, il peut être un régulateur linéaire quadratique.
- La boîte froide peut contenir une réserve de gaz caloporteur liquéfié qui s'évapore en partie sous l'effet de la charge thermique d'un consommateur, le gaz évaporé étant évacuée par le conduit de refoulement et remplacé par la liquéfaction d'au moins une partie du gaz provenant dudit conduit d'amenée, la variabilité dans le temps des taux d'évaporation et de liquéfaction du gaz induisant de ce fait des perturbations dans la pression à l'intérieur desdits conduits d'amenée et de refoulement.
- Le consommateur peut être un aimant supraconducteur présentant une charge thermique pulsée.
- Said control device may comprise: a first controller for generating a first control signal of said valves based on a first partial model of the system; a second regulator for generating a second driving signal of said valves based on a second partial model of the system, different from said first partial model; and a control selector for selectively applying to said valves the first or second control signal.
- Said regulation system may comprise: a heat transfer gas storage tank at an intermediate pressure between that of said supply duct and that of said discharge duct; a first controlled valve disposed between said storage tank and said discharge pipe for allowing gas injection therefrom from said tank; a second controlled valve, disposed between said storage tank and said supply pipe, to allow evacuation of gas from the latter to said tank; and a third controlled valve, disposed between said supply conduit and said delivery conduit, to allow bypass of the cold box.
- Said first regulator may be adapted to generate a first opening control signal of the first and third valves, excluding said second valve, based on said first partial model of the system; and said second regulator may be adapted to generate a second opening control signal of the second and third valves, excluding said first valve, based on said second partial model of the system.
- Said first partial model can model the behavior of the system when a volume of gas is injected into the discharge pipe, and said second partial model can model the behavior of the system when a volume of gas is extracted from the supply duct.
- Said mathematical model of the system can model heat transfer flow disturbances induced by temporal variations of the thermal load of a consumer in thermal communication with said cold box by virtual variations of the openings of the valves of the control system, the latter being supplied to said control device as input variables next to measured values and pressure setpoints
- Said control device can be adapted to minimize a cost function depending on the differences between the pressures measured in the supply and discharge pipes and the values of respective setpoints, as well as the amplitude of the generated control signals. In particular, it can be a quadratic linear regulator.
- The cold box may contain a liquefied heat transfer gas reserve which evaporates in part under the effect of the heat load of a consumer, the evaporated gas being discharged through the discharge pipe and replaced by the liquefaction of at least one part of the gas from said supply duct, the variability over time of evaporation rates and liquefaction of the gas thereby inducing disturbances in the pressure inside said supply and discharge ducts.
- The consumer may be a superconducting magnet having a pulsed thermal load.
D'autres caractéristiques, détails et avantages de l'invention ressortiront à la lecture de la description faite en référence aux dessins annexés donnés à titre d'exemple et qui représentent, respectivement :
- La
figure 1A , un schéma d'un système cryogénique selon l'art antérieur; - La
figure 1B , le principe de « commande partagée »
(« split range ») mis en oeuvre dans le système de lafigure 1A ; - La
figure 2 , un diagramme de principe du moyen de régulation d'un système cryogénique selon un mode de réalisation de l'invention ; et - Les
figures 3A, 3B et 3C et 4A, 4B, 4C , des graphiques illustrant le comportement d'un système cryogénique selon l'invention sous charge thermique pulsée, et sa comparaison avec l'art antérieur.
- The
Figure 1A a diagram of a cryogenic system according to the prior art; - The
Figure 1B , the principle of "shared control"
("Split range") implemented in the system ofFigure 1A ; - The
figure 2 a principle diagram of the regulating means of a cryogenic system according to one embodiment of the invention; and - The
FIGS. 3A, 3B and 3C and 4A, 4B, 4C , graphs illustrating the behavior of a cryogenic system according to the invention under pulsed thermal load, and its comparison with the prior art.
La
Une telle installation comporte un circuit cryogénique comprenant une conduite à haute pression CHP, une conduite à basse pression CBP, un étage de compression CMP et une boîte froide BF.Such an installation comprises a cryogenic circuit comprising a high pressure line CHP, a low pressure line CBP, a compression stage CMP and a cold box BF.
L'étage de compression CMP peut comporter un ou plusieurs compresseurs, par exemple de type à vis, ainsi qu'un déhuileur non représenté. Le gaz - Hélium en particulier - comprimé par l'étage de compression s'écoule dans la conduite à haute pression, ou conduite d'amenée CHP, à une pression PHP de l'ordre de 15 -20 bar, en direction de la boîte froide BF ; on indique par QCMP le débit massique du compresseur, supposé constant.The compression stage CMP may comprise one or more compressors, for example of the screw type, as well as an unrepresented deoiler. The gas - Helium in particular - compressed by the compression stage flows in the high pressure line, or supply line CHP, at a pressure P HP of the order of 15 -20 bar, in the direction of the cold box BF; the mass flow rate of the compressor, assumed to be constant, is indicated by Q CMP .
A l'intérieur de la boîte froide, le flux de gaz caloporteur (Hélium) se subdivise en deux : un débit QJT traverse une vanne de détente à effet Joule-Thomson VJT (après un pré-refroidissement éventuel à l'azote liquide, non représenté), tandis que le débit restant traverse une turbine de détente TD. Bien que cela ne soit pas représenté sur la figure, le gaz refroidi par son passage à travers la turbine TD est injecté dans des échangeurs à contre-courant et utilisé pour pré-refroidir le flux qui traverse la vanne de Joute-Thomson, en amont de cette dernière, selon le principe du cycle de Claude.Inside the cold box, the flow of heat transfer gas (Helium) is subdivided in two: a flow rate Q JT passes through a Joule-Thomson V JT expansion valve (after a possible pre-cooling with liquid nitrogen , not shown), while the remaining flow passes through an expansion turbine TD. Although this is not shown in the figure, the gas cooled by its passage through the turbine TD is injected into countercurrent exchangers and used to pre-cool the flow through the Joute-Thomson valve, upstream. of the latter, according to the principle of Claude's cycle.
Une fraction QL JT du débit QJT traversant la vanne Joule-Thomson VJT est liquéfiée suite à la détente dans ladite vanne. Le gaz liquide ainsi produit alimente un bain thermique BT, tandis que la fraction QV JT = QJT-QL JT demeure à l'état gazeux. Le rapport QV JT/QL JT dépend notamment de la température amont de la vanne de détente.A fraction Q L JT flow Q JT through the Joule-Thomson V JT valve is liquefied following expansion in said valve. Liquid gas thus produced feeds a thermal bath BT, while the fraction JT = Q V Q L Q JT JT remains in the gaseous state. The Q V JT / Q L JT ratio depends in particular on the upstream temperature of the expansion valve.
Un consommateur CONS, représenté par une résistance électrique, est en communication thermique avec le bain BT. Ce consommateur dissipe sous la forme de chaleur une puissance Θ (« charge thermique ») qui provoque l'évaporation d'un débit QW de gaz liquide. Ce débit QW, ainsi que le débit QV JT et le débit traversant la turbine de détente sont évacués de la boîte froide par le conduit de refoulement à basse pression CBP (PBP de l'ordre de 1,05 bar) vers le compresseur CMP.A consumer CONS, represented by an electrical resistance, is in thermal communication with the bath BT. This consumer dissipates in the form of heat a power Θ ("thermal load") which causes the evaporation of a flow rate Q W of liquid gas. This flow rate Q W , as well as the flow rate Q V JT and the flow rate passing through the expansion turbine, are discharged from the cold box via the low pressure discharge pipe CBP (P BP of the order of 1.05 bar) towards the CMP compressor.
Comme ledit compresseur fonctionne à vitesse - et donc à débit volumétrique - constant, la pression dans les conduits CHP et CBP est régulée grâce à un système de vannes commandées VC1, VC2 et VC3.Since said compressor operates at a constant speed - and therefore at a volumetric flow rate - the pressure in the CHP and CBP ducts is regulated by means of a controlled valve system VC 1 , VC 2 and VC 3 .
Une réserve de stockage de gaz RS à une pression PRS, intermédiaire entre PBP et PHP (par exemple, de l'ordre de 9 bar) est connectée au conduit à basse pression CBP par l'intermédiaire d'une première vanne commandée VC1, et au conduit à haute pression CHP par l'intermédiaire d'une deuxième vanne commandée VC2. Lorsque la première vanne VC1 est ouverte, un débit QVC1 de gaz est injecté dans l'installation à partir de la réserve RS ; inversement, lorsque la deuxième vanne VC2 est ouverte, un débit QVC2 de gaz est évacué de l'installation pour être stocké dans la réserve RS. Les deux vannes VC1, VC2 ne doivent jamais être ouvertes en même temps.A gas storage tank RS at a pressure P RS , intermediate between P BP and P HP (for example, of the order of 9 bar) is connected to the low pressure pipe CBP via a first valve controlled VC 1 , and to the high-pressure pipe CHP via a second valve VC 2 controlled. When the first valve VC 1 is open, a flow rate Q VC1 of gas is injected into the installation from the reserve RS; conversely, when the second valve VC 2 is open, a flow rate Q VC2 of gas is removed from the installation to be stored in the reserve RS. Both valves VC 1 , VC 2 must never be opened at the same time.
Une troisième vanne commandée VC3 fixe le point de fonctionnement de l'installation en ouvrant et fermant une voie de contournement de la boîte froide, traversée par un débit QVC3 de gaz.A third valve VC 3 controls the operating point of the installation by opening and closing a bypass path of the cold box, crossed by a flow rate Q VC3 gas.
D'une manière conventionnelle (voir l'article précité de J.-C. Boissin et al.), les vannes VC1. VC2 et VC3 sont commandées par deux régulateurs indépendants, généralement de type PID (proportionnel - intégral - dérivée) pour maintenir les valeurs de pression PBP et PHP proches de valeurs de consigne respectifs P0 BP et P0 HP.In a conventional manner (see the aforementioned article by J.-C. Boissin et al.), Valves VC 1 . VC 2 and VC 3 are controlled by two independent regulators, generally of the PID type (proportional - integral - derivative) to maintain the pressure values P BP and P HP close to respective reference values P 0 BP and P 0 HP .
Comme le montre la
Le signal SC12 peut commander les deux vannes VC1 et VC2 grâce à un mécanisme de « commande partagée » (« split range ») SR, dont le fonctionnement est illustré sur la
Les inventeurs ce sont rendus compte du fait que cette stratégie de régulation est responsable du comportement dynamique peut satisfaisant de l'installation CRY. En effet, les valeurs de pression dans les conduits à haute et à basse pression sont couplés par l'intermédiaire de la boîte froide BF, mais ce couplage n'est pas pris en compte par les deux régulateurs indépendants PID1 et PID2 ; cela engendre un effet de « pompage » en cas de variation rapide de la charge thermique Θ. En effet, si une perturbation modifie rapidement la valeur de PBH, le premier régulateur PID1 réagit pour la neutraliser ; mais à cause du couplage introduit par la boîte froide, l'action de PID1 perturbe inévitablement la valeur de PHP, ce qui déclenche l'intervention du deuxième régulateur PID2. A son tour, ce dernier perturbe à nouveau la valeur de PBP, et ainsi de suite.The inventors are aware that this control strategy is responsible for the satisfactory dynamic behavior of the CRY installation. Indeed, the pressure values in the high and low pressure pipes are coupled via the cold box BF, but this coupling is not taken into account by the two independent regulators PID1 and PID2; this gives rise to a "pumping" effect in the event of rapid variation of the heat load Θ. Indeed, if a disturbance rapidly changes the value of P BH , the first PID1 regulator reacts to neutralize it; but because of the coupling introduced by the cold box, the action of PID1 inevitably disturbs the value of P HP , which triggers the intervention of the second PID2 regulator. In turn, it again disrupts the value of P BP , and so on.
Cette découverte a permis aux inventeurs de proposer une nouvelle stratégie de commande prenant en compte ledit couplage haute pression/basse pression par l'utilisation d'un régulateur multivariable, par exemple du type linéaire quadratique, en remplacement des deux régulateurs PID indépendants de l'art antérieur.This discovery allowed the inventors to propose a new control strategy taking into account said high pressure / low pressure coupling by the use of a multivariable regulator, for example of the quadratic linear type, replacing the two independent PID regulators of the prior art.
La méthode de commande multivariable dite « linéaire quadratique » est bien connue de l'art antérieur ; voir par exemple les ouvrages :
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« Contrôle optimale : théorie et applications », Emmanuel Trelat, Editions Vuibert, collections : Mathématiques concrètes, 2e édition ISBN : 9782711722198, en particulier le chapitre 1 -
« Optimal control: linear quadratics methods » ; de B.D.O Anderson et J.B Moore, Dover publications, ISBN 9780486457666
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"Optimal control: theory and applications", Emmanuel Trelat, Editions Vuibert, collections: Concrete Mathematics, 2nd edition ISBN: 9782711722198, in particular Chapter 1 -
"Optimal control: linear quadratics methods"; by BDO Anderson and JB Moore, Dover Publications, ISBN 9780486457666
Fondamentalement, il s'agit d'un schéma de commande optimale d'un système dynamique défini par un système d'équations différentielles linéaire, dans lequel la fonction de coût est représentée par une fonctionnelle quadratique de l'écart entre les variables de commande (PHP, PBP) et leurs consignes respectives (P0 HP, P0 BP), et des intensités des signaux de commande. Dans ces conditions, la commande optimale (c'est à dire qui minimise la fonction de coût) peut être obtenue par résolution d'une équation algébrique de Riccati.Basically, it is an optimal control scheme of a dynamic system defined by a system of linear differential equations, in which the cost function is represented by a quadratic functional of the difference between the control variables (P HP , P BP ) and their respective setpoints (P 0 HP , P 0 BP ), and intensities of the control signals. Under these conditions, the optimal control (that is to say, which minimizes the cost function) can be obtained by solving an algebraic equation of Riccati.
En fait, la mise en oeuvre d'une régulation multivariable dans l'installation cryogénique de la
Conformément à invention, ce problème peut être résolu en appliquant une technique connue comme « commutation de commande ». Dans cette technique, on modélise le système à commander par une pluralité de sous-systèmes indépendants, chacun pourvu d'un régulateur propre, parmi lesquels le système réel « commute ». En l'espèce, l'installation cryogénique SYS peut être modélisée à l'aide de deux modèles partiels décrivant le fonctionnement de l'installation en régime d'apport et de retrait de matière respectivement. A chaque instant, deux signaux de commande vectoriels sont générés, un pour chaque modèle partiel ; un sélecteur de commande choisit lequel de ces signaux de commande doit être effectivement appliqué à l'installation.According to the invention, this problem can be solved by applying a technique known as "control switching". In this technique, the system to be controlled is modeled by a plurality of independent subsystems, each with its own controller, of which the actual system "switches". In this case, the cryogenic plant SYS can be modeled using two partial models describing the operation of the plant in material supply and withdrawal respectively. At each moment, two vector control signals are generated, one for each partial model; a control selector chooses which of these control signals must be effectively applied to the installation.
Les modèles partiels sont linéarisés autour du point de fonctionnement de l'installation, ce qui ne peut pas être fait pour un modèle « global » censé rendre compte du comportement du système dans les deux régimes à la fois.The partial models are linearized around the point of operation of the installation, which can not be done for a "global" model that is supposed to account for the behavior of the system in both regimes at the same time.
Le principe de la commutation de commande est connu, par exemple, des publications suivantes :
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D. Liberzon et S. Morse, « Basic Problems in Stability and Design of Switched Systems », IEEE Control Systems Magazine, Octobre 1999, pages 59 - 70 -
M. Zefran et J. W. Burdick « Design of switching controllers for system with changing dynamics », Proceedings of 37th Conference on Decision and Control, 1998
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D. Liberzon and S. Morse, "Basic Problems in Stability and Design of Switched Systems," IEEE Control Systems Magazine, October 1999, pages 59-70 -
M. Zefran and JW Burdick, "Design of switching controllers for system with changing dynamics," Proceedings of 37th Conference on Decision and Control, 1998
Un régulateur mettant en oeuvre les principes de l'invention sera décrit plus en détail en référence à la
Les valeurs de pression PHP et PBP, mesurées dans les conduits CHP et CBP respectivement, sont fournies en entrée à un modèle mathématique MOD de l'installation CRY, constitué par deux sous-modèles ou modèles partiels MP1, MP2, représentant le fonctionnement de l'installation en régime d'apport et de retrait de matière respectivement. Ces modèles permettent d'associer aux variations temporelles des pressions PHP et PBP des variations « virtuelles » d'ouverture des vannes CV1, CV2. Autrement dit, les modèles partiels permettent de calculer des « ouvertures virtuelles » OV 1. OV 2 desdites vannes qui, si elles étaient réelles, produiraient les fluctuations de pression observées (qui, en réalité, sont engendrées essentiellement par les variations de charge thermique, non mesurées directement). On dit que les perturbations du système sont « ramenées sur les entrées ». Il est important de noter que les deux ouvertures virtuelles dépendent à la fois de PHP et PBP : les modèles du système prennent en compte les couplages existants entre les régions à haute et à basse pression de l'installation.The pressure values P HP and P BP , measured in the CHP and CBP ducts respectively, are input to a mathematical model MOD of the CRY installation, consisting of two submodels or partial models MP 1 , MP 2 , representing the operation of the installation in terms of intake and removal of material respectively. These models make it possible to associate with the temporal variations of the pressures P HP and P BP "virtual" variations of opening of the valves CV 1 , CV 2 . In other words, the partial models make it possible to calculate "virtual openings" O V 1 . O V 2 of said valves which, if real, would produce the observed pressure fluctuations (which, in reality, are generated mainly by thermal load variations, not measured directly). It is said that the disturbances of the system are "brought back to the entrances". It is important to note that the two virtual openings depend on both P HP and P BP : the system models take into account the existing couplings between the high and low pressure regions of the installation.
On dispose ainsi d'un vecteur constitué par six variables scalaires d'entrée, dépendantes du temps : tes pressions mesurées dans les conduits, PHP et PBP ; les valeurs de consigne respectives, P0 HP, P0 BP ; et les « ouvertures virtuelles » OV 1. OV 2. Ce vecteur est fourni en entrée à un dispositif de commande DC, constitué par un premier et un deuxième régulateurs, DC1 et DC2. Ces deux régulateurs - mutuellement indépendants - sont du type linéaire quadratique et basés sur le premier et le deuxième modèle partiel, respectivement.We thus have a vector consisting of six scalar input variables, dependent on time: the pressures measured in the ducts, P HP and P BP ; the respective setpoints, P 0 HP , P 0 BP ; and the "virtual openings" O V 1 . O V 2 . This vector is input to a control device DC consisting of a first and a second regulator, DC 1 and DC 2 . These two mutually independent regulators are of the quadratic linear type and based on the first and second partial models, respectively.
Le premier régulateur DC1 est destiné à commander l'installation cryogénique CRY en régime d'apport de matière : pour ce faire, il engendre des signaux de commande (ou un premier signal vectoriel de commande) SC1 et SC'3 destinés à piloter les vannes CV1 et CV3 respectivement. Par contre, ce régulateur n'agit pas sur la vanne CV2 qui, en régime d'apport de matière, est censée rester à l'état fermé.The first DC regulator 1 is intended to control the CRY cryogenic installation in material supply regime: to do this, it generates control signals (or a first vector signal of control) SC 1 and SC ' 3 for controlling the valves CV 1 and CV 3 respectively. On the other hand, this regulator does not act on the valve CV 2 which, in material supply regime, is supposed to remain in the closed state.
Réciproquement, le deuxième régulateur DC2 est destiné à commander l'installation cryogénique CRY en régime de retrait de matière : pour ce faire, il engendre des signaux de commande (ou un deuxième signal vectoriel de commande) SC2 et SC"3 destinés à piloter les vannes CV2 et CV3 respectivement. Par contre, ce régulateur n'agit pas sur la vanne CV1 qui, en régime de retrait de matière, est censée rester à l'état fermé.Conversely, the second DC 2 regulator is intended to control the CRY cryogenic installation in material removal regime: to do this, it generates control signals (or a second vector control signal) SC 2 and SC " 3 intended to control the valves CV 2 and CV 3 respectively. for against, this controller does not act on the valve CV 1 which, on the withdrawal system, is expected to remain in the closed state.
Il est intéressant de noter que le premier régulateur fournit un signal de commande SC1 de la vanne CV1 même lorsque le système se trouve en régime de retrait de matière ; dans ce cas, cependant, ce signal de commande correspondra à un niveau d'ouverture de ladite vanne non physiquement réalisable - par exemple négatif. Il en va de même pour le signal de commande SC2 engendré par le deuxième régulateur lorsque le système se trouve, en réalité, en régime d'apport de matière. Cela permet à un sélecteur de commande SELC de sélectionner les signaux de commande SCS 1, SCS 2, SCS 3 qui seront réellement appliqués aux vannes CV1, CV2 et CV3 respectivement. Par exemple :
- Si SC1<0, alors : SCS 1= 0; SCS 2= SC2; SCS 3= SC"3 (fonctionnement en régime de retrait de matière, le régulateur DC2 commande le système) ;
- Si SC2<0, alors : SCS 1= SC1; SCS 2= 0; SCS 3 = SC'3 (fonctionnement en régime d'apport de matière, le régulateur DC1 commande le système).
- If SC 1 <0, then: SC S 1 = 0; SC S 2 = SC 2 ; SC S 3 = SC " 3 (operation in material removal mode, the DC 2 controller controls the system);
- If SC 2 <0, then: SC S 1 = SC 1 ; SC S 2 = 0; SC S 3 = SC ' 3 (operation in material supply regime, the controller DC 1 controls the system).
On pourrait également utiliser des régulateurs DC1, DC2 non linéaires, fournissant uniquement des signaux d'ouverture physiquement réalisables ; dans ce cas, la sélection de commande se ferait en identifiant lequel parmi les signaux SC1 et SC2 est le plus proche de zéro.Non-linear DC 1 , DC 2 controllers could also be used, providing only physically feasible opening signals; in this case, the control selection would be by identifying which of the signals SC 1 and SC 2 is closest to zero.
On discutera maintenant, de manière synthétique, quelle peut être la forme des modèles partiels utilisés pour la mise en oeuvre de la commande du système.We will now discuss, in a synthetic way, what can be the form of the partial models used for the implementation of the system control.
Le point de départ pour obtenir ces modèles est constitué par les équations de conservation de la masse à l'intérieur des sections à basse pression (mBP) et à haute pression (mHP) du système SYS :
Tous les termes à la droite de ces équations ont été décrits plus haut, en référence à la
Or:
- QVC3 dépend linéairement de PHP et non-linéairement du niveau d'ouverture de la vanne VC3, représenté par ouv3 ; le flux gazeux dans le chemin de contoumement étant sonique, le débit ne dépend pas de la pression aval PBP. On peut donc écrire : QVC3=f3(PHP, ouv3).
- QVC1 dépend linéairement de PRS et non-linéairement du niveau d'ouverture de la vanne VC1, représenté par ouv1 ; le flux gazeux dans le chemin de contournement étant sonique, le débit ne dépend pas de la pression aval PBP. Comme la pression de la réserve PRS est considéré constante, on peut écrire : QVC1=f1(ouv1).
- QVC2 dépend non-linéairement à la fois de PHP, de la différence PHP-PRS (le flux est subsonique, car la pression amont PHP est inférieur à deux fois la pression aval PRS, par conséquent la pression aval doit être prise en considération) et du niveau d'ouverture de la vanne VC2, représenté par ouv2. En « cachant » la constante PRS dans la fonction non-linéaire f2 on peut donc écrire : QVC2=f2(PHP, ouv2).
- Qw dépend linéairement du flux thermique (ou charge thermique) Θ du consommateur : QW=KW·Θ.
- QCMP dépend linéairement de PBP, en supposant que le débit volumétrique du compresseur est constant et que la densité du gaz est proportionnelle à sa pression : QCMP=KCMP· PBP, avec KCMP constant.
- QV JT dépend essentiellement de la température du gaz au niveau de la vanne de détente VJT ; il s'agit d'un paramètre indépendant des autres, qui peut être considéré constant.
- Q VC3 depends linearly on P HP and non-linearly on the opening level of valve VC 3 , represented by open 3 ; the gas flow in the contoement path being sonic, the flow rate does not depend on the downstream pressure P BP . We can write: Q VC3 = f 3 (P HP , open 3 ).
- Q VC1 depends linearly on P RS and non-linearly on the opening level of valve VC 1 , represented by open 1 ; the gas flow in the bypass path being sonic, the flow rate does not depend on the downstream pressure P BP . As the pressure of the reserve P RS is considered constant, one can write: Q VC1 = f 1 (open 1 ).
- Q VC2 depends non-linearly from both P HP , the difference P HP -P RS (the flow is subsonic, because the upstream pressure P HP is less than twice the downstream pressure P RS , therefore the downstream pressure must be taken into consideration) and the opening level of the valve VC 2 , represented by open 2 . By "hiding" the constant P RS in the non-linear function f 2 we can write: Q VC2 = f 2 (P HP , open 2 ).
- Qw linearly depends on the thermal flux (or thermal load) Θ of the consumer: Q W = K W · Θ.
- Q CMP depends linearly on P BP , assuming that the volumetric flow rate of the compressor is constant and that the density of the gas is proportional to its pressure: Q CMP = K CMP · P BP , with constant K CMP .
- Q V JT depends essentially on the gas temperature at the expansion valve V JT ; it is a parameter independent of the others, which can be considered constant.
L'équation d'état du gaz (qui peut être supposé parfait) permet de lier les masses mBP, mHP aux pressions correspondantes PBP, PHP.The equation of state of the gas (which can be supposed perfect) makes it possible to bind masses m BP , m HP to the corresponding pressures P BP , P HP .
En remplaçant ces expressions dans les équations de conservation de la masse on obtient un système de deux équations différentielles non linéaires pour les pressions PBP, PHP :
FBP et FHP sont deux fonctions non-linéaires qui peuvent être linéarisées autour de deux points de fonctionnement :
- un premier point de fonctionnement correspondant au régime d'apport de matière, caractérisé par ouv2=0 ; et
- un deuxième point de fonctionnement correspondant au régime de retrait de matière, caractérisé par ouv1=0.
- a first operating point corresponding to the material feed regime, characterized by O 2 = 0; and
- a second operating point corresponding to the material withdrawal regime, characterized by open 1 = 0.
La linéarisation de ces équations permet d'écrire les deux sous-systèmes correspondant auxdits points de fonctionnement sous la forme de représentations d'état dans lesquelles les valeurs de pression PBP, PHP définissent les états, les niveaux d'ouverture des vannes ouv1, ouv2 et ouv3 représentent les commandes et la charge thermique Θ constitue une perturbation externe.The linearization of these equations makes it possible to write the two subsystems corresponding to said operating points in the form of state representations in which the pressure values P BP , P HP define the states, the opening levels of the open valves. 1 , open 2 and open 3 represent the controls and the thermal load Θ constitutes an external disturbance.
Les équations linéarisées permettent également de calculer les « ouvertures virtuelles » OV 1, OV 2 en fonction des pressions PBP, PHP mesurées.The linearized equations also make it possible to calculate the "virtual openings" O V 1 , O V 2 as a function of the pressures P BP , P HP measured.
Il est donc possible de concevoir deux régulateurs multivariables pour ces deux sous-systèmes par des techniques conventionnelles. Il est particulièrement avantageux d'utiliser une commande optimale de type linéaire quadratique.It is therefore possible to design two multivariable controllers for these two subsystems using conventional. It is particularly advantageous to use an optimal command of the quadratic linear type.
Les
Des essais ont été réalisés en envoyant à un consommateur (résistance électrique) des impulsions de puissance de 300W de forme rectangulaire, d'une durée de 50 s et avec une période de 100 s. Les courbes ΘINV et ΘREF sur la
Les
Les
Claims (10)
- A cryogenic system for cooling a consumer (CONS) presenting a thermal load (Θ) that varies over time, the system comprising:· a cold box (BF) in thermal contact with said consumer, fed with a compressed heat-conveying gas by a delivery pipe (CHP) and connected to a return pipe (CBP) for exhausting said gas at a lower pressure; and· a unit for regulating the pressures in said delivery and return pipes, the unit comprising a plurality of controlled valves (CV1, CV2, CV3) and a control device (MC) for controlling the opening of said valves;
the system being characterized in that said control device is a multivariable regulator adapted to generate opening control signals (SCS 1, SCS 2, SCS 3) for said valves as a function of measured values (PHP, PBP) and of setpoint values (P0 HP, P0 BP) for the pressures of said delivery and return pipes on the basis of a mathematical model of the system, which model takes account of coupling between the pressure values in the delivery and return pipes via said cold box. - A system according to claim 1, wherein said control device comprises:· a first regulator (MC1) for generating a first signal for controlling said valves on the basis of a first partial model of the system;· a second regulator (MC2) for generating a second signal for controlling said valves on the basis of a second partial model of the system that is different from said first partial model; and· a control selector (SELC) for selectively applying the first or the second control signal to said valves.
- A cryogenic system according to either preceding claim, wherein said regulation unit comprises:· a supply (RS) of heat-conveying gas at a pressure that is intermediate between the pressure of said delivery pipe and that of said return pipe;· a first controlled valve (VC1) arranged between said supply and said return pipe in order to enable gas to be injected into the return pipe from said supply;· a second controlled valve (VC2) arranged between said supply and said delivery pipe in order to enable gas to be exhausted from the delivery pipe to said supply; and· a third controlled valve (VC3) arranged between said delivery pipe and said return pipe in order to enable the cold box to be bypassed.
- A system according to claims 2 and 3, wherein said first regulator is adapted to generate a first control signal (SC1, SC'3) for opening the first and third valves, to the exclusion of said second valve, on the basis of said first partial model of the system; and said second regulator is adapted to generate a second control signal (SC2, SC"3) for opening the second and third valves, to the exclusion of said first valve, on the basis of said second partial model of the system.
- A system according to any one of claims 2, 3 in combination with claim 4 or 4, wherein said first partial model models the behavior of the system when a volume of gas is injected into the return pipe, and said second partial model models the behavior of the system when a volume of gas is extracted from the delivery pipe.
- A system according to any preceding claim, wherein said mathematical model of the system models the disturbances in the flow rate of the heat-conveying gas that are induced by variations over time in the heat load
of a consumer in thermal communication with said cold box, by means of virtual variations in the openings of the valves of the regulation system, said virtual openings being supplied to said control device as input variables together with the measured and setpoint values for the pressures. - A system according to any preceding claim, wherein said control device is adapted to minimize a cost function that depends on the differences between the pressures measured in the delivery and return pipes and the respective setpoint values therefor, and also on the amplitudes of the control signals generated.
- A system according to claim 7, wherein said control device is a linear quadratic regulator.
- A system according to any preceding claim, wherein the cold box contains a supply of liquefied heat-conveying gas (BT) that evaporates in part under the effect of the thermal load of a consumer, the evaporated gas being exhausted via the return pipe and replaced by liquefying at least some of the gas coming from said delivery pipe, the variability over time in the gas evaporation and liquefaction rates, thereby giving rise to disturbances in the pressures within the delivery and return pipes.
- A system according to any preceding claim, wherein the consumer is a superconductive magnet that presents a pulsed thermal load.
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FR0901374A FR2943768B1 (en) | 2009-03-24 | 2009-03-24 | CRYOGENIC SYSTEM FOR COOLING A CONSUMER HAVING A VARIABLE THERMAL LOAD IN TIME. |
PCT/FR2010/000236 WO2010109091A1 (en) | 2009-03-24 | 2010-03-22 | Cryogenic system for cooling a consumer having a time-variable heat load |
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EP2411745A1 EP2411745A1 (en) | 2012-02-01 |
EP2411745B1 true EP2411745B1 (en) | 2013-07-10 |
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EP10712464.6A Not-in-force EP2411745B1 (en) | 2009-03-24 | 2010-03-22 | System for cryogenic cooling for consumer cooling with temporally variable load |
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FR2985805B1 (en) | 2012-01-12 | 2016-12-23 | Commissariat Energie Atomique | METHOD FOR CONTROLLING A COMPRESSION DEVICE OF A COOLANT FLUID OF A REFRIGERATING MACHINE |
FR3001533B1 (en) | 2013-01-29 | 2015-02-27 | Commissariat Energie Atomique | METHOD FOR DETERMINING A MODEL OF A THERMODYNAMIC SYSTEM |
RU2631841C2 (en) | 2013-05-31 | 2017-09-26 | Майекава Мфг. Ко., Лтд. | Cooling device based on brayton cycle |
US10054357B2 (en) * | 2016-10-12 | 2018-08-21 | Raytheon Company | Purity monitor |
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-
2010
- 2010-03-22 EP EP10712464.6A patent/EP2411745B1/en not_active Not-in-force
- 2010-03-22 US US13/258,686 patent/US20120055664A1/en not_active Abandoned
- 2010-03-22 JP JP2012501338A patent/JP2012521535A/en active Pending
- 2010-03-22 WO PCT/FR2010/000236 patent/WO2010109091A1/en active Application Filing
Also Published As
Publication number | Publication date |
---|---|
US20120055664A1 (en) | 2012-03-08 |
FR2943768B1 (en) | 2011-04-29 |
EP2411745A1 (en) | 2012-02-01 |
WO2010109091A1 (en) | 2010-09-30 |
FR2943768A1 (en) | 2010-10-01 |
JP2012521535A (en) | 2012-09-13 |
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