EP3830469B1 - Connected backfeeding installation and method for operating such an installation - Google Patents

Description

TECHNICAL AREA

The present invention relates to a connected countdown installation and a method of operating such an installation. It applies, in particular, to gas transport networks to export surplus renewable gas from a distribution network to a transport network with greater reception capacity, by supplying a larger consumption area. vast, even storage, thanks to the storage facilities connected to it.

STATE OF THE ART

Biogas production is experiencing strong growth in Europe and its valorization conditions the creation of a sustainable methanization sector. In the following, “biomethane” defines the gas produced from raw biogas from the anaerobic methanization of organic waste (biomass) or by high temperature gasification (followed by synthesis by methanation); purified and treated to make it interchangeable with mains natural gas.

If the most common recovery method is the production of heat and/or electricity, recovery in the form of fuel and the injection of biomethane into the natural gas network are also under development.

The injection of biomethane into the natural gas network is already carried out in Europe. In a context of strong development of biomethane, natural gas distributors find themselves faced with situations of lack of outlet. In fact, the consumption of domestic customers varies on average from 1 to 10 between winter and summer on public distributions. The injection of biomethane is initially possible only if it is done at a flow rate lower than the minimum flow rate recorded during periods of lower consumption or if the biomethane is produced as close as possible to consumption. When production exceeds quantities consumed, this tends to saturate the distribution networks during hot seasons. This situation limits the development of the biomethane production sector through the congestion of natural gas distribution networks. Several solutions have been identified to resolve this problem: the networking of distribution networks to increase the consumption capacities of biomethane produced by the multiplication of connected consumers, the modulation of biomethane production according to the seasons and consumption needs, the micro -liquefaction and compression to store biomethane production during seasons of low consumption, the development of gas uses (for mobility, in particular), as well as the creation of countdown stations between the natural gas distribution and transport networks.

Backflow installations are thus one of the solutions identified to develop biomethane injection capacities. These installations make it possible to export surplus biomethane from a distribution network to the transport network, by compressing them and reinjecting them into this transport network to thus benefit from its greater gas storage capacity. Thus, producers would no longer have to limit their production and the profitability of their projects would be more easily ensured. The countdown station is a work of the transport operator allowing the transfer of gas from the distribution network to the transport network with a large storage capacity, via a gas compression station. The countdown station can be located either near the expansion station, or at another location where the transmission and distribution networks intersect.

The countdown therefore integrates a gas compression function to adapt it to the constraints imposed by the downstream of this compressor, that is to say the transport network. Current countdowns are fixed installations in which compressors are placed in buildings. Each compressor is driven by an electric motor connected to the electrical network.

However, the pressure and flow of gas in the distribution network are very variable, in particular depending on the injection of biogas by a producer or the consumption of gas by consumers, for example industrial sites. The simple regulation of gas pressure in the distribution network can thus lead to activating the reverse installation to export gas into the transport network, then a few moments later, release gas from the transport network to supply it to the network. of distribution. The operation of the countdown installation may thus be only partially effective.

Furthermore, the configurations of distribution networks are changing, particularly when a biogas supplier is connected to it and injects biogas into it or disconnects from it. At the same time, gas consumption on this distribution network may increase or decrease, for example when a factory or large consuming area is installed or when it is shut down. Again, the operation of the countdown installation may be partially ineffective.

Today, the countdown equipment is controlled automatically based on orders transmitted by an operator and/or by information directly collected on the site of the countdown installation. The systems implemented therefore do not allow optimal management of the installation by taking into account elements collected externally at the reverse site. In addition, the supervision of the installation of countdowns and the configuration of analyzers is only possible in person, on the countdown installation. This requires a strong presence of operational teams on site.
We know the document FROM 10 2009 038 128 which discloses a countdown installation positioned between two gas networks of different pressure, the activation and deactivation of which depends on predetermined fixed thresholds.

STATEMENT OF THE INVENTION

The present invention aims to remedy all or part of these drawbacks.

• au moins un compresseur pour comprimer du gaz en provenance d'un réseau,
• un automate de commande de fonctionnement d'au moins un compresseur,
• un moyen de communication à distance pour recevoir au moins une valeur instantanée de pression captée à distance sur le réseau en amont de l'installation de rebours,
• un moyen de prédiction d'évolution de la pression dans le réseau en amont de l'installation de rebours, en fonction, au moins, des valeurs de pression reçues,
• un moyen de détermination d'une valeur limite de pression pour l'arrêt ou le démarrage d'au moins un compresseur en fonction de la prédiction d'évolution de la pression,

l'automate commandant l'arrêt ou le fonctionnement d'au moins un compresseur lorsque la pression en entrée de chaque compresseur est inférieure, respectivement supérieure, à la valeur limite de pression déterminée.To this end, according to a first aspect, the present invention aims at a countdown installation comprising:

• at least one compressor for compressing gas coming from a network,
• a controller for controlling the operation of at least one compressor,
• a means of remote communication for receiving at least one instantaneous pressure value captured remotely on the network upstream of the countdown installation,
• a means of predicting the evolution of the pressure in the network upstream of the backflow installation, depending, at least, on the pressure values received,
• a means for determining a pressure limit value for stopping or starting at least one compressor as a function of the pressure evolution prediction,

the automaton controlling the stopping or operation of at least one compressor when the inlet pressure of each compressor is lower, respectively higher, than the determined pressure limit value.

In embodiments, the prediction means implements dynamic learning and profiles of consumers, suppliers, capacities and response times of the countdown facility.

In embodiments, the prediction means implements artificial intelligence algorithms and/or neural networks.

In embodiments, the prediction means uses historical data, in particular, for a large number of dates and times, pressures observed at different points of the distribution network and triggering and stopping of safety devices, pressure relief , countdowns, consumption, injections.

In embodiments, the prediction means uses weather data.

• le profil de consommation ou d'injection de gaz,
• la distance jusqu'à l'installation de rebours,
• le volume de gaz ou la surface de la section moyenne de canalisation, jusqu'à l'installation de rebours.

In embodiments, the prediction means uses for each gas consumer and for each gas supplier present on the distribution network:

• the gas consumption or injection profile,
• the distance to the timer installation,
• the volume of gas or the surface area of the average pipe section, up to the installation of backs.

In embodiments, the prediction means uses the topology of the distribution network, with its branches and the positions of the sensors.

In embodiments, the prediction means uses operating rise curves of the expansion station and the countdown installation.

In embodiments, the prediction means is configured to determine preferential times for maintenance or inspection stops minimizing a cost function of these stops.

In embodiments, the prediction means is configured to predict pressures, within a horizon of a few minutes or a few hours.

In embodiments, the prediction means is configured to predict maximum and minimum setpoint pressure values.

In embodiments, the countdown installation further comprises a means of determining a load rate of each compressor as a function of the pressure evolution prediction, the automaton controlling the operation of each compressor to achieve the determined charging rate.

• un moyen d'analyse de qualité de gaz à compresser
• un moyen de communication à distance pour recevoir au moins une valeur instantanée de qualité de gaz captée à distance en amont ou en aval de l'installation de rebours,
• un moyen de prédiction d'évolution de la qualité de gaz dans le réseau en amont de l'installation de rebours, en fonction, au moins, des valeurs de qualité reçues,
• un moyen de détermination d'une valeur limite de qualité de gaz pour l'arrêt d'au moins un compresseur en fonction de la prédiction d'évolution de la qualité,

l'automate commandant l'arrêt d'au moins un compresseur lorsque la qualité en entrée de chaque compresseur est inférieure à la valeur limite de qualité déterminée.In embodiments, the countdown installation further comprises,

• a means of analyzing the quality of gas to be compressed
• a means of remote communication for receiving at least one instantaneous gas quality value captured remotely upstream or downstream of the countdown installation,
• a means of predicting changes in gas quality in the network upstream of the reverse installation, based, at least, on the quality values received,
• a means for determining a gas quality limit value for stopping at least one compressor based on the prediction of changes in quality,

the automaton controlling the stopping of at least one compressor when the quality at the input of each compressor is lower than the determined quality limit value.

In embodiments, the countdown installation further comprises a means of determining a loading rate of each compressor as a function of the prediction of the evolution of the quality, the automaton controlling the operation of each compressor to achieve the determined charging rate.

• au moins un compresseur pour comprimer du gaz en provenance d'un réseau et
• un automate de commande de fonctionnement d'au moins un compresseur ; procédé qui comporte les étapes suivantes :
  • une étape de réception, depuis un capteur distant, d'au moins une valeur instantanée de pression captée à distance de l'installation de rebours,
  • une étape de prédiction d'évolution de la pression dans le réseau en amont de l'installation de rebours,
  • une étape de détermination d'une valeur limite de pression pour l'arrêt ou le démarrage d'au moins un compresseur en fonction de la prédiction d'évolution de la pression,
  • une étape d'arrêt ou de démarrage, respectivement, du fonctionnement d'au moins un compresseur lorsque la pression en entrée de chaque compresseur est inférieure, respectivement supérieure, à la valeur limite de pression déterminée.

According to a second aspect, the present invention relates to a method of operating a countdown installation comprising:

• at least one compressor for compressing gas coming from a network and
• a controller for controlling the operation of at least one compressor; process which comprises the following steps:
  • a step of receiving, from a remote sensor, at least one instantaneous pressure value captured remotely from the countdown installation,
  • a step of predicting the evolution of the pressure in the network upstream of the backflow installation,
  • a step of determining a pressure limit value for stopping or starting at least one compressor based on the pressure evolution prediction,
  • a step of stopping or starting, respectively, the operation of at least one compressor when the inlet pressure of each compressor is lower, respectively higher, than the determined pressure limit value.

• une étape de détermination de valeurs de charge de la compression à appliquer en fonction de la prédiction d'évolution de la pression,
• une étape de régulation du fonctionnement de chaque compresseur pour atteindre le taux de charge à appliquer.

In embodiments, the method further comprises:

• a step of determining the compression load values to be applied according to the pressure evolution prediction,
• a step of regulating the operation of each compressor to achieve the load rate to be applied.

• une étape de réception, depuis un capteur distant, d'au moins une valeur instantanée de qualité de gaz captée à distance de l'installation de rebours,
• une étape de prédiction d'évolution de la qualité de gaz en amont de l'installation de rebours,
• une étape de détermination d'une valeur limite de qualité de gaz pour l'arrêt de chaque compresseur en fonction de la prédiction d'évolution de la qualité,
• une étape d'arrêt du fonctionnement de chaque compresseur lorsque la qualité de gaz en entrée de chaque compresseur est inférieure, à la valeur limite de qualité déterminée.

In embodiments, the method further comprises:

• a step of receiving, from a remote sensor, at least one instantaneous gas quality value captured remotely from the countdown installation,
• a step of predicting changes in gas quality upstream of the reverse installation,
• a step of determining a gas quality limit value for stopping each compressor based on the prediction of changes in quality,
• a step of stopping the operation of each compressor when the quality of gas at the inlet of each compressor is lower than the determined quality limit value.

• une étape de détermination de valeurs de charge de la compression à appliquer en fonction de la prédiction d'évolution de la qualité de gaz et
• une étape de régulation du fonctionnement de chaque compresseur pour atteindre le taux de charge à appliquer.

In embodiments, the method further comprises:

• a step of determining compression load values to be applied according to the prediction of evolution of the gas quality and
• a step of regulating the operation of each compressor to achieve the load rate to be applied.

The advantages, aims and particular characteristics of this process being identical to those of the installation which is the subject of the invention, they are not recalled here.

BRIEF DESCRIPTION OF THE FIGURES

• la figure 1 représente, sous forme d'un schéma bloc, une installation de rebours objet de l'invention,
• la figure 2 représente, partiellement et sous forme d'un schéma bloc, un réseau de transport et un réseau de distribution munis de moyens de communication avec l'installation de rebours objet de l'invention,
• la figure 3 représente, partiellement et sous forme de schéma, un réseau de transport et de distribution avec des positionnements d'équipements de mesure et de résultats de calcul,
• la figure 4 représente un algorithme de détermination de calcul de charge d'un compresseur en fonction de données distantes,
• la figure 5 représente, sous forme d'un logigramme, des étapes de fonctionnement d'une installation de rebours objet de l'invention,
• la figure 6 représente des évolutions de débit et de pression lors de la régulation en débit du fonctionnement de l'installation de rebours,
• la figure 7 représente des évolutions de débit et de pression lors de la régulation en pression du fonctionnement de l'installation de rebours,
• la figure 8 illustre, sous forme de courbes, des évolutions de prédiction de pression et de valeur limite de déclenchement d'au moins un compresseur et
• la figure 9 illustre, sous forme de courbes, des évolutions de prédiction de pression et de valeur limite de déclenchement d'un poste de détente et de livraison.

Other advantages, aims and characteristics of the present invention will emerge from the description which follows, given for explanatory and in no way limiting purposes, with reference to the appended drawings, in which:

• there figure 1 represents, in the form of a block diagram, a countdown installation which is the subject of the invention,
• there figure 2 represents, partially and in the form of a block diagram, a transport network and a distribution network provided with means of communication with the countdown installation which is the subject of the invention,
• there Figure 3 represents, partially and in diagram form, a transport and distribution network with positions of measuring equipment and calculation results,
• there Figure 4 represents an algorithm for determining the load calculation of a compressor based on remote data,
• there Figure 5 represents, in the form of a flowchart, the operating steps of a countdown installation which is the subject of the invention,
• there Figure 6 represents changes in flow and pressure during flow regulation of the operation of the backflow installation,
• there Figure 7 represents changes in flow and pressure during pressure regulation of the operation of the backflow installation,
• there figure 8 illustrates, in the form of curves, changes in pressure prediction and trigger limit value of at least one compressor and
• there Figure 9 illustrates, in the form of curves, changes in pressure prediction and triggering limit value of an expansion and delivery station.

DESCRIPTION OF MODES OF CARRYING OUT THE INVENTION

• l'analyse et le contrôle 19 de la qualité de gaz à compresser en conformité aux prescriptions techniques de l'opérateur de transport,
• le comptage 20 des quantités transférées,
• la compression du gaz en provenance du réseau de distribution 15, par au moins un compresseur 21, il s'agit généralement de compresseurs à moteur électrique et à pistons, avec deux ou trois étages de compression,
• la régulation 24 en pression ou en débit,
• la filtration 22, amont et aval,
• la gestion 18 de la stabilité du fonctionnement du réseau de distribution,
• les organes de sécurité 26 et
• les outils de pilotage 24 et de suivi de l'installation de rebours.

There figure 1 schematically represents a countdown installation which is the subject of the invention. The countdown installation has a set of technical functions making it possible to create a gas flow by controlling the operating conditions specific to a transport network 10 and a distribution network 15. These functions include:

• analysis and control 19 of the quality of gas to be compressed in accordance with the technical requirements of the transport operator,
• counting 20 the quantities transferred,
• the compression of the gas coming from the distribution network 15, by at least one compressor 21, these are generally compressors with an electric motor and pistons, with two or three compression stages,
• regulation 24 in pressure or flow,
• filtration 22, upstream and downstream,
• management 18 of the stability of the operation of the distribution network,
• security organs 26 and
• 24-hour management and monitoring tools for the countdown installation.

• de la pression d'exploitation du réseau de transport 10 et de celle du réseau de distribution 15. La première doit être comprise entre 30 et 60 bars sur le réseau régional et peut atteindre 85 bars sur le réseau principal. La seconde est de l'ordre de 4 à 19 bars sur les réseaux MPC (Réseau Moyenne Pression de type C, soit une pression entre 4 et 25 bars) et inférieure à 4 bars sur les réseaux MPB (Réseau Moyenne Pression de type B, soit une pression entre 50 millibars et 4 bars),
• de la capacité maximale de production des producteurs de biométhane 17 susceptibles d'injecter du biométhane dans le réseau de distribution 15, capacité qui varie de quelques dizaines de Nm³/h pour les plus petites unités, à plusieurs centaines de Nm³/h pour les plus grosses,
• de la consommation des consommateurs 16 sur le réseau de distribution 15, notamment la consommation minimale et
• de la faculté du réseau de distribution 15 à absorber des variations de pression (volume en eau).

These different functions are described below. There are also utilities (electrical sources, communications network, etc.) necessary for operating an industrial installation. The countdown installation is sized taking into account:

• of the operating pressure of the transport network 10 and that of the distribution network 15. The first must be between 30 and 60 bars on the regional network and can reach 85 bars on the main network. The second is of the order of 4 to 19 bars on MPC networks (Medium Pressure Network type C, i.e. a pressure between 4 and 25 bars) and less than 4 bars on MPB networks (Medium Pressure Network type B, i.e. a pressure between 50 millibars and 4 bars),
• of the maximum production capacity of biomethane producers 17 capable of injecting biomethane into the distribution network 15, a capacity which varies from a few tens of Nm ³ /h for the smallest units, to several hundred Nm ³ /h for the biggest,
• of consumer consumption 16 on the distribution network 15, in particular the minimum consumption and
• of the ability of the distribution network 15 to absorb variations in pressure (water volume).

All of these data make it possible to determine the maximum flow rate of the countdown installation and to estimate its operating time. This duration may vary, depending on the case, from occasional operation (10 to 15% of the time) to almost permanent operation. This exercise must also take into account the fact that the installations of producers 17 are not put into service simultaneously but over the years.

• une unité de déshydratation 29 à l'amont de la compression 21, pour réduire les risques de condensation sur le réseau haute pression de transport, de formation d'hydrates et de corrosion,
• en option, un laboratoire d'analyse des paramètres de combustion (indice de Wobbe, pouvoir calorifique et densité de gaz) pour injecter les injecter les relevés dans le système de détermination des énergies de l'opérateur de transport.

Concerning the analysis 19 of gas conformity, discrepancies exist between the gas quality specifications applied to the transmission 10 and distribution 15 networks, due to different operating pressures, infrastructure, materials, uses and interfaces with underground storage. The specifications of the transport networks 10 are generally the most restrictive than those of the distribution networks 10. Thus, to guarantee that the installation of gas return from the distribution network 15 to the transport network 10 fits into the operational operation of the transport network 10, the following provisions are planned:

• a dehydration unit 29 upstream of compression 21, to reduce the risks of condensation on the high pressure transport network, hydrate formation and corrosion,
• as an option, a laboratory for analyzing combustion parameters (Wobbe index, calorific value and gas density) to inject the readings into the transport operator's energy determination system.

At the discretion of the transport operator, the analysis of other compound contents (CO ₂ , H ₂ O, THT, etc.) is optional and is only carried out if there is a proven risk of contamination of the transport network 10 (example: reversal of a biomethane with a high CO ₂ content without the possibility of dilution on the distribution networks 15 and transport 10, or operated at a very high pressure).

Concerning gas counting 20, the countdown installation is equipped with a counting chain consisting of a counter and a local or regional energy determination device in accordance with legal metrology.

• un compresseur 21 réalisant 100 % du besoin de rebours maximum,
• deux compresseurs 21 réalisant chacun 100 % du besoin de rebours maximum où
• deux compresseurs 21 réalisant chacun 50 % du besoin de rebours maximum.

Concerning gas compression, the compression unit makes it possible to compress the surplus biomethane production at the operating pressure of the transport network 10. Depending on economic criteria and availability of the installation, several configurations are possible, for example example :

• a compressor 21 achieving 100% of the maximum countdown requirement,
• two compressors 21 each realizing 100% of the maximum countdown requirement where
• two compressors 21 each performing 50% of the maximum countdown requirement.

The configuration is chosen by a study of the different advantages and disadvantages in terms of costs, availability, size, and possibility of evolution of the compression unit. The suction pressure to be considered is the service pressure of the distribution network 15, which depends in particular on the injection pressures of the biomethane producers 17. The construction pressure at discharge to be considered is the maximum service pressure (“PMS” ) of the transport network, for example 67.7 bars. To ensure start-up, anti-pumping protection of each compressor 21 (excluding piston compressor) or operation in stabilized recycling, a recycling circuit 27 provided with a valve 28 can be provided. The recycling circuit expands gas at the second pressure and injects it upstream of the compressor when at least one compressor is put into operation, under the control of a controller 25.

The sealing of each compressor 21 can be carried out with oil or with a dry seal. In the first case, certain filtration arrangements are put in place (see below).

The automaton 25 performs the functions of piloting 24, operating control, loading rate and stopping of each compressor 21 and regulation and stability 18 of the network 15. Note that, throughout the description, the term “automaton” means an automaton or a computer system or a set of automatons and/or computer systems (for example one automaton per function).

Concerning regulation, the evolution of the pressure of the distribution network 15 near the backflow installation is correlated to the flow rate of gas passing through the installation backwards. These developments are the result of the dynamic operation of gas consumption on the distribution network 15, of the capacities injected with biomethane by producers 17 and of the operation of the delivery installation, through a valve 14, and countdowns . We therefore integrate possibilities for adapting the operating range of the suction pressure of the backflow installation, as well as regulation of the compressors 21 which can anticipate the constraints exerted on the distribution network 15, according to the configurations encountered. This is a difference with delivery stations without countdown, for which the pressure is regulated at the delivery point so as to be fixed, regardless of consumption by consumers 16. Consequently, the mode of regulation (pressure or flow) of the reverse flow towards the transport network 10 is adapted to the proper functioning of the reverse installation.

According to the specifications of the compressors and to avoid their deterioration or due to the constraints linked to the operation of the transport network 10, filtration is provided in the gas quality compliance function, upstream of compression to recover any liquids and dust contained in the gas coming from the distribution network 15. In addition, in the case of an oil-sealed compressor 21, a coalescer filter 22 is installed at the outlet of the compressor 21, for example with a manual purge and a visual level.

A cooling system 23 cools all or part of the compressed gas to maintain the temperature downstream, towards the transport network 10, at a value below 55°C (equipment certification temperature). To ensure the operation of the cooling system 23, it is sized from relevant ambient temperature values according to meteorological histories.

Delivery station 12 is an installation, located at the downstream end of the transport network, which allows the delivery of natural gas according to the needs expressed by the customer (pressure, flow rate, temperature, etc.). It is therefore the gas expansion interface from the transport network 10 to the distribution network 15 or to certain industrial installations. The delivery station 12 therefore integrates expansion valves to reduce the pressure to adapt to the conditions imposed downstream.

• nombre de cycles de démarrage et d'arrêt de chaque compresseur 21 et sa compatibilité avec les recommandations du fournisseur du compresseur 21,
• le démarrage et l'arrêt de chaque compresseur 21 par une routine, faisant suite à une temporisation,
• l'utilisation d'un volume tampon (non représenté) en amont de chaque compresseur 21, pour amortir les variations de pression et de débit du réseau de distribution 15.

To avoid instability phenomena, the countdown installation must not operate simultaneously with the expansion station 12 and delivery from the transport network 10 to the distribution network 15. Limit values for starting and stopping the countdown installation are set accordingly and each automaton 25 of an installation combining trigger 12 and countdown is adapted so as to prohibit the simultaneity of these two functions. The countdown installations, during their start-up, operation and shutdown phase, limit disturbances to the upstream network (distribution 15) and the downstream network (transport 10) by avoiding in particular triggering pressure safety devices at the delivery station 12. The following parameters are taken into account:

• number of start and stop cycles of each compressor 21 and its compatibility with the recommendations of the compressor supplier 21,
• starting and stopping each compressor 21 by a routine, following a time delay,
• the use of a buffer volume (not shown) upstream of each compressor 21, to cushion variations in pressure and flow rate of the distribution network 15.

• un mode de fonctionnement automatique,
• une visualisation/supervision du fonctionnement de l'installation de rebours et
• le démarrage de l'installation de rebours.

A control and supervision function carried out by the automaton 25 makes it possible to obtain:

• an automatic operating mode,
• visualization/supervision of the operation of the countdown installation and
• starting the installation countdown.

Data logging is carried out to document operating conditions.

In the event of an emergency, the countdown installation is isolated from the distribution network 15, by closing the valve 14. An “emergency stop” function makes it possible to stop and secure the countdown installation. The countdown installation is also equipped with pressure and temperature safety devices 26. There is no automatic venting unless contraindicated by safety studies. The countdown installation is equipped with fire and gas detection systems 26. A means of protection against overflows is provided to protect the devices, in the form of a physical organ such as a restriction orifice or by the via an automation.

Note that the flow rate of a countdown can vary from a few hundred to a few thousand Nm ³ /h depending on the case.

• d'un moyen de communication à distance 9, configuré pour recevoir au moins une valeur instantanée de pression et au moins une valeur instantanée de qualité de gaz captées à distance sur le réseau en amont de l'installation de rebours,
• d'un moyen de stockage 8 de données historiques et de prédiction,
• d'un moyen de détermination 7 d'une valeur limite de pression pour l'arrêt ou le démarrage d'au moins un compresseur 21, en fonction de la prédiction d'évolution de la pression,
• d'un moyen 6 de détermination d'un taux de charge à appliquer à chaque compresseur 21 en fonction de la prédiction d'évolution de la pression, l'automate 25 commandant le fonctionnement de chaque compresseur 21 pour atteindre le taux de charge déterminé,
• un moyen 5 de prédiction d'évolution de la qualité de gaz dans le réseau en amont de l'installation de rebours, en fonction, au moins, des valeurs de qualité reçues,
• un moyen 4 de détermination d'une valeur limite de qualité de gaz pour l'arrêt d'au moins un compresseur 21 en fonction de la prédiction d'évolution de la qualité, l'automate 25 commandant l'arrêt d'au moins un compresseur lorsque la qualité en entrée de chaque compresseur est inférieure à la valeur limite de qualité déterminée,
• un moyen 3 de détermination d'un taux de charge à appliquer à chaque compresseur 21 en fonction de la prédiction d'évolution de la qualité, l'automate 25 commandant le fonctionnement de chaque compresseur pour atteindre le taux de charge déterminé.
• un moyen 2 de sélection automatique d'un mode de régulation, soit en débit, soit en pression (par exemple, entre deux valeurs limites (SH et SB), le mode de régulation est une régulation en débit et, en dehors de l'intervalle entre ces deux valeurs limites, le mode de régulation est une régulation en pression.

The automaton 25 is equipped with:

• a remote communication means 9, configured to receive at least one instantaneous pressure value and at least one instantaneous gas quality value captured remotely on the network upstream of the backflow installation,
• a means of storing 8 historical and prediction data,
• a means 7 for determining a pressure limit value for stopping or starting at least one compressor 21, as a function of the pressure evolution prediction,
• means 6 for determining a load rate to be applied to each compressor 21 as a function of the pressure evolution prediction, the automaton 25 controlling the operation of each compressor 21 to reach the determined load rate,
• a means 5 for predicting changes in the gas quality in the network upstream of the reverse installation, depending, at least, on the quality values received,
• a means 4 for determining a gas quality limit value for stopping at least one compressor 21 as a function of the prediction of changes in quality, the automaton 25 controlling the stopping of at least one compressor when the input quality of each compressor is lower than the determined quality limit value,
• a means 3 for determining a load rate to be applied to each compressor 21 as a function of the prediction of the evolution of the quality, the automaton 25 controlling the operation of each compressor to achieve the determined load rate.
• a means 2 for automatic selection of a regulation mode, either in flow or in pressure (for example, between two limit values (SH and SB), the regulation mode is flow regulation and, apart from the interval between these two limit values, the regulation mode is pressure regulation.

There figure 2 represents the gas transmission network 10, the distribution network 15, the consumers 16, the biomethane producers 17, the expansion and delivery station 12 and the countdown installation 30.

The transport network 10 is provided with a communicating pressure sensor 31 and a communicating flow sensor 32. The distribution network 15 is provided with a communicating pressure sensor 33 and a communicating flow sensor 34. A communicating weather information source 35 provides geolocated weather data. Finally, the biomethane producers 17 are connected to the distribution network 15 by injection points equipped with communicating flow sensors 36.

A computer network (not shown), for example the Internet on a mobile telephone network, connects all the communicating sensors.

The storage and prediction means 8 analyzes the data received from the various sensors and the source 35, in particular the pressure 33 and flow sensors 34 and provides, depending on the meteorological data and the days and times of the week (taking into account taking into account public holidays and summer and winter hours), a prediction of consumption on the distribution network 15.

• un partage de données entre le gestionnaire du réseau de distribution, en amont de l'installation de rebours, et le gestionnaire du réseau de transport, en aval du rebours,
• la mise à disposition de données « mouvement de gaz » à l'exploitant (accès à des pressions et débits du réseau), exploitant qui peut ainsi orienter certaines interventions comme déterminer les durées suivantes :
  • ∘ durée dont il dispose pour intervenir sur l'installation entière ou en partie (exemple, le traitement du gaz, l'analyse du gaz) sans perturber les producteurs de biométhane,
  • ∘ durée dont il dispose avant de devoir intervenir sur site avant impact chez le producteur de biométhane, voire la nécessité ou pas, d'intervenir.
• la télé-exploitation et la télémaintenance de l'installation de l'installation de rebours.

The invention therefore makes the collection and transmission of data available to the countdown installation. It therefore offers an exchange of data on three distinct aspects:

• data sharing between the distribution network manager, upstream of the reverse flow installation, and the transport network manager, downstream of the reverse flow,
• the provision of “gas movement” data to the operator (access to network pressures and flow rates), the operator who can thus guide certain interventions such as determining the following durations:
  • ∘ duration available to intervene on the entire installation or in part (example, gas treatment, gas analysis) without disturbing biomethane producers,
  • ∘ duration available before having to intervene on site before impact at the biomethane producer, or even the need or not to intervene.
• remote operation and remote maintenance of the installation of the reverse installation.

Concerning the sharing of data between the network managers, the transport network manager 10, as operator of the backflow installation, has quality data of the incoming gas and pressure and flow data of the distribution network .

The exchange of gas quality data makes it possible to determine the characteristics of the gas such as the composition or the GC (High Calorific Value) at the level of the backflow installation and to avoid carrying out additional analyzes on this backflow installation. Compared to existing reverses, this innovation therefore makes it possible to save on certain analyzers and thus reduce investment costs on reverses, but also to temporarily dispense with certain analyzers. To do this, the biomethane stations injecting into the distribution network in question record process gas and safety information in real time, this information is then sent via internet link to a server processing this data and making it accessible to the distribution network manager. 15.

• une vérification directe des valeurs sur le réseau de distribution avec les valeurs limites (« seuils ») autorisées sur le réseau aval,
• un calcul des mélanges de gaz réalisés sur le réseau de distribution avec les valeurs limites autorisées sur le réseau aval, par
  • ∘ soit un calcul en pourcentage molaire en amont du poste rebours,
  • ∘ soit des systèmes de traçage de la qualité par simulation des durées de transits en régime stationnaire, voire en intégrant les régimes dynamiques,
  • ο soit des systèmes de construction par maillage (par exemple de type Lagrangien) permettant de la reconstruction (le calcul) des données manquantes, dans ce cas, les données en entrée de la compression.

Different algorithms can be used:

• a direct verification of the values on the distribution network with the limit values (“thresholds”) authorized on the downstream network,
• a calculation of the gas mixtures made on the distribution network with the limit values authorized on the downstream network, by
  • ∘ i.e. a calculation in molar percentage upstream of the countdown station,
  • ∘ either quality tracking systems by simulating transit times in stationary conditions, or even by integrating dynamic regimes,
  • ο or mesh construction systems (for example of the Lagrangian type) allowing the reconstruction (calculation) of missing data, in this case, the compression input data.

• les valeurs limites pouvant être admises sur le réseau aval pouvant être évolutives en fonction des caractéristiques du gaz du réseau aval et des quantités y transitant. Par exemple, un gaz circulant sans hydrogène (H₂) sur le réseau en aval de la compression pourra accepter un gaz en amont de la compression au prorata molaire du mélange des deux gaz jusqu'à la limite admissible sur le réseau.

The parameters of the mathematical model are the network description data (roughness, diameter, length, then possibly, second order data such as linearity, heat exchange coefficients of the pipe and the ground, burial depth , or any other values allowing the description of the structure to be refined in the model), the model being supplied by the temporal data on gas quality, flow and pressure available to the upstream network,

• the limit values that can be admitted on the downstream network can be scalable depending on the characteristics of the gas in the downstream network and the quantities passing through it. For example, a gas circulating without hydrogen (H ₂ ) on the network downstream of compression will be able to accept a gas upstream of compression in molar proportion of the mixture of the two gases up to the admissible limit on the network.

The sharing of pressures and flow rates in real time from the distribution network 15 connected to the backflow installation 30 is carried out by pressure sensors connected and positioned on certain critical points of the distribution network 15 highlighted by static studies and dynamic. This sharing of data makes it possible to optimize the management of the countdown installation (in particular on stopping/starting and charging) and to secure the process by anticipating the risks and impacts on the distribution network 15.

THE figures 3 And 4 describe transport and distribution networks and a control algorithm that can be implemented, this making it possible to define the load level, the need to start a compressor (case where the load rate is equal to 100% ). Likewise, a low threshold can be defined allowing a compressor to be stopped. A transport network 10 and a distribution network 15 are interfaced by a countdown installation 30 and a relaxation and distribution station 42. Note that the countdown installation 30 can be fixed, mobile (for example made up of transportable modules on trucks) or scalable (the installation including locations and connectors for adding compressors).

• trois points de livraison vers le réseau secondaire dit « de distribution » 15 (deux biométhanes 40 et 41 et un poste de détente et de livraison 42 du réseau de transport distant de l'installation de rebours 30),
• cinq points de livraison 43 à 47 du réseau secondaire (légende : carré marqué d'un « L » indicé),
• cinq capteurs de mesures de pression 48 à 52 (légende : rond marqué de « PM » indicé),
• quatre pressions calculées 53 à 56 (légende : rond marqué d'un « PC » indicé). On note que les capteurs de mesures de pression et les lieux de calcul de pression ont été placés en figure 3 sans rechercher la compatibilité avec un calcul.

There Figure 3 presents in particular a distribution network with:

• three delivery points to the secondary so-called “distribution” network 15 (two biomethanes 40 and 41 and an expansion and delivery station 42 from the transport network distant from the reverse installation 30),
• five delivery points 43 to 47 of the secondary network (legend: square marked with a subscripted “L”),
• five pressure measurement sensors 48 to 52 (legend: round marked with “PM” indexed),
• four calculated pressures 53 to 56 (legend: circle marked with a subscripted “PC”). We note that the pressure measurement sensors and the pressure calculation locations were placed in Figure 3 without looking for compatibility with a calculation.

There Figure 4 is an example of a mathematical function for defining the compression load rate. The coefficients k are determined by simulation or by measurements on the network which may require testing, they can also be derived from artificial intelligence by learning. The coefficients k express the importance (in other words, the weight or criticality) of the measurement point in relation to the control constraint. If the information from simulation or prior measurement analysis only designates a restrictive measurement point for control, then this is called a critical point (it is the point used for control). In the proposed algorithm, the coefficient k makes it possible to change the critical point according to changes in pressure evolutions.

• PX = PM ou PC
• PX_{max_i} : pression max pouvant être atteinte à ce point, toutes les PX_{max_i} sont identiques dans le cas de la figure 3
• PX_{min_i} : pression min pouvant être atteinte à ce point.

In Figure 4 :

• PX = PM or PC
• PX _{max_i} : maximum pressure that can be reached at this point, all PX _{max_i} are identical in the case of Figure 3
• PX _{min_i} : min pressure that can be reached at this point.

During a step 61, it is determined whether the minimum, for any value of i, of k _{pX_hi} * (PX _{max_i} - Pc _i )) > _{Load_max} threshold

If not, during a step 62, we apply the formula load (%) = 100 * min _{all i} (k _{pX_bi} * (PX _i - P _{xmin_i} )). If the result of step 61 is positive, during a step 63, the charging rate is set to 100%.

Thus, the closer the charge level is to 100% on its low regulation level, the more the knowledge of the charge by the algorithm of the Figure 4 Allows you to speed up or slow down compression (also called “load rate”) based on the distance between the nearest high and low limits. The acceleration and deceleration speeds can be calculated by PID (Proportional/Integral/Derivative).

The operation optimization component aims to make network pressure and flow data available to the transport network 10 operating teams, both in real time and over a period of several months. This allows the operator to visualize the network pressure and flow data in the form of a functional diagram. He can thus analyze a situation more quickly and better understand his intervention by having knowledge of all the parameters of the network, something which is not the case today. This also allows alarms to be raised when simultaneously the countdown installation 30 is operating and the injection station 12 is delivering. This feedback to the operator is based on the technology used for the “@home” applications of National Dispatching and Regional Surveillance Centers (CSR), in retrieving information from the remote management system and presenting it in a form that can be directly used by the intervention teams.

The data made available to the operating teams are the source data resulting from the acquisition, as well as all the data (intermediate and final) calculated by the algorithms proposed for the implementation of the invention, these calculated data being time stamped. . This data allows intervention teams to carry out their own analyses, for example simple pro rata calculations or by comparison with similar situations already encountered. The data collected allows, thanks to their timestamp, the operating teams to evaluate the time they have before a need for intervention, to evaluate the consequences of a reduction in the load rate on a possible postponement of the intervention, or even a capacity for non-intervention.

The computer network for the installation of countdowns also integrates remote diagnostics and remote maintenance functionalities for the internal operational teams of the transport network manager 10 and the contractors in charge of part of the maintenance. The innovation lies in the possibility of remotely viewing the views of the supervision/human-machine interface of the countdown installation and of being able to configure the analyzers remotely and not only in person. These solutions facilitate maintenance operations, reduce the mobilization time of teams (reduction of journeys, concordance of the schedules of the different actors involved, etc.) and the unavailability of the countdown installation, in comparison with existing countdown installations.

• une première valeur limite de pression servant au déclenchement du fonctionnement de chaque compresseur 21 de l'installation de rebours 30 et, éventuellement, pour le circuit de recyclage 27 et la vanne 28,
• une deuxième valeur limite de pression servant pour l'arrêt du fonctionnement de chaque compresseur 21 de l'installation de rebours 30,
• une troisième valeur limite de pression servant pour le déclenchement du poste de détente et de fourniture 12, et
• une quatrième valeur limite de pression servant pour l'arrêt du poste de détente et de fourniture 12 ;

en fonction :

• de la prédiction de consommation fournie par le moyen de prédiction 8,
• des données reçues des différents capteurs, notamment les capteurs de pression 33 et de débit 34 et 36.

The automaton 25 sets:

• a first pressure limit value used to trigger the operation of each compressor 21 of the reverse installation 30 and, possibly, for the recycling circuit 27 and the valve 28,
• a second pressure limit value used to stop the operation of each compressor 21 of the reverse installation 30,
• a third pressure limit value used to trigger the expansion and supply station 12, and
• a fourth pressure limit value used for stopping the expansion and supply station 12;

in function :

• of the consumption prediction provided by the prediction means 8,
• data received from the various sensors, in particular the pressure 33 and flow sensors 34 and 36.

Then, when the pressure of the distribution network 15 exceeds the first limit value thus fixed, the automaton 25 triggers the operation of at least one compressor 21 and, possibly, the valve 28. Conversely, when the pressure of the distribution network 15 crosses, while decreasing, the second limit value thus fixed, the automaton 25 stops the operation of each compressor 21.

There Figure 5 details the steps of a process 70 for operating the automaton 25 controlling the countdown installation 30. It is assumed, in the Figure 5 that each compressor 21 of the installation 30 is stopped and that the expansion and delivery station 12 is also stopped.

During a step 71, the automaton 25 receives and stores instantaneous pressure and flow values coming from the various sensors, in particular the remote pressure 33 and flow sensors 34. The automaton 25 receives and puts also in memory, preferably, instantaneous gas quality values captured remotely from the countdown installation 30.

During a step 72, the automaton 25 receives and stores meteorological data, in particular the air temperature and the wind.

During a step 73, the automaton 25 makes a prediction of consumption on the distribution network 15, based on the data stored in memory, the day of the week and the time and the weather data received. The day of the week, the time, the air temperature and the wind allow, in particular, the automaton 25 to predict the consumption of consumers 16, by statistical and predictive processing of data stored in memory, for example over a period of one hour. By subtracting the average flow rate by the producers 17, captured at the injection points, by the sensors 36, and depending on the average injection duration for each of the producers, an evolution of the pressure in the network is predicted. distribution 15.

During step 73, the prediction of the evolution of the pressure in the network upstream of the reverse installation is carried out, and the prediction of the evolution of the gas quality upstream of the reverse installation.

• une première valeur limite de pression servant à l'arrêt du fonctionnement de chaque compresseur 21 de l'installation de rebours 30 et, éventuellement, pour le circuit de recyclage 27 et la vanne 28,
• une deuxième valeur limite de pression servant pour l'arrêt du fonctionnement de chaque compresseur 21 de l'installation de rebours 30,
• une troisième valeur limite de pression servant pour l'arrêt du poste de détente et de fourniture 12,
• une quatrième valeur limite de pression servant pour l'arrêt du poste de détente et de fourniture 12 et
• une valeur limite de qualité de gaz pour l'arrêt de chaque compresseur en fonction de la prédiction d'évolution de la qualité,

During a step 74, depending on the pressure prediction, the controller determines:

• a first pressure limit value used to stop the operation of each compressor 21 of the reverse installation 30 and, possibly, for the recycling circuit 27 and the valve 28,
• a second pressure limit value used to stop the operation of each compressor 21 of the reverse installation 30,
• a third pressure limit value used to stop the expansion and supply station 12,
• a fourth pressure limit value used for stopping the expansion and supply station 12 and
• a gas quality limit value for stopping each compressor based on the quality change prediction,

In particular, as illustrated in figure 8 , if the prediction 93 shows, in the absence of delivery or compression, the imminent occurrence of a temporary maximum 94 of the pressure at a level lower than the pressure 90 temporarily tolerated by the distribution network 15, the first limit value 91 is increased to a value 92 greater than or equal to this maximum 93. This case occurs, for example, when producers inject biomethane into the distribution network a few moments before the probable start of professional, industrial or commercial consuming installations of gas at times 95 and 96. This avoids triggering the compression of gas by the compressor 21, followed, a few moments later, by the stopping of this compressor 21 and the stopping of the expansion and delivery station 12 .

Conversely, as illustrated in Figure 9 , if the prediction 93 shows, in the absence of delivery or compression, the imminent occurrence of a temporary minimum 97 of pressure, the third limit value 98 is set at a value 99 less than or equal to this minimum 97. This case occurs, for example, a few moments before the probable shutdown 101 of professional, industrial or commercial installations consuming gas while biomethane producers begin, at a moment 100, an injection of biomethane of which we know, by declaration or by learning , that the duration will extend beyond the predicted reduction in consumption. This avoids triggering the expansion and delivery station 12 followed, a few moments later, by stopping the expansion and delivery station and stopping the gas compression by the compressor 21.

• que la compression ne soit jamais simultanée à la détente et la livraison (la deuxième valeur limite est toujours supérieure à la quatrième valeur limite) et
• que l'évolution prévisible de la pression (la compensation de l'évolution de pression en tenant compte de la compression et de la livraison) reste proche de la pression nominale de fonctionnement du réseau de distribution 15.

The second and fourth limit values are set at intermediate levels between the first and third limit values for:

• that compression is never simultaneous with expansion and delivery (the second limit value is always greater than the fourth limit value) and
• that the predictable evolution of the pressure (compensation of the pressure evolution taking into account compression and delivery) remains close to the nominal operating pressure of the distribution network 15.

The four limit values are thus optimized to limit the number of start and stop cycles of each compressor 21 and the number of start and stop cycles of the expansion and delivery station 12.

During a step 75, the automaton 25 determines whether the gas pressure in the distribution network 15 exceeds the first or fourth limit values upwards or the second or third limit value decreases. If yes, the automaton 25 triggers, respectively, the stopping of at least one compressor 21, the stopping of the expansion and delivery station 12, the stopping of each compressor 21 or the activation of the expansion station and delivery 12.

During step 75, the automaton 25 commands the operation of each compressor 21 to stop when the quality of gas at the inlet of each compressor 21 is lower than the determined quality limit value.

We continue, during a step 76, the capture of physical quantities of pressure and flow. During steps 77 and 78, when at least one compressor 21 is put into operation, the controller 25 controls the operation of the recycling circuit 27 and the valve 28 to dampen the pressure oscillations upstream and downstream of each compressor 21. Then, we return to step 71.

During step 77, the automaton 25 determines the compression load values to be applied based on the pressure evolution prediction. During step 78, the automaton 25 regulates the operation of each compressor 21 to achieve the charging rate thus determined. Optionally, the automaton 25 also determines, during step 77, compression load values to be applied according to the prediction of evolution of the gas quality. In this case, during step 78, the automaton 25 regulates the operation of each compressor 21 to achieve the charging rate thus determined.

• calcul de simulation permettant de disposer de la pression maximum autorisée à l'aspiration,
• calcul de simulation permettant de disposer de la pression minimum à l'aspiration,
• l'intégral de l'écart entre la pression corrélée et la pression minimum multiplié par le volume en eau du réseau amont permet de définir le débit pouvant être absorbé par la compression rebours dans la période de temps considérée,
• l'intégral de l'écart entre la pression corrélée et la pression maximum multiplié par le volume en eau permet de définir le débit pouvant être réduit dans la compression rebours dans la période de temps considérée,
• par comparaison des deux valeurs précédentes aux capacités du compresseur (débit minimum et maximum), le débit à comprimer est calculé. Celui-ci doit répondre :
  • ∘ s'il est détecté, au besoin de démarrer un autre compresseur, d'augmenter le débit des compresseurs en fonctionnement, jusqu'à ce que ce besoin disparaisse,
  • ∘ s'il est détecté, au besoin d'arrêter un compresseur, de minimiser le débit des compresseurs en fonctionnement, jusqu'à ce que ce besoin disparaisse.

Concerning step 73, the predictions are made by conventional statistical calculations. Of course, these could be replaced by artificial intelligence in order to increase performance. The statistical establishment data that can be used are, in a non-exhaustive manner, the pressures of the upstream network, the gas inlet flow rates, calendar data such as weekends, public holidays and holidays, meteorological data (for example , measured temperature, felt, hydrometry, wind), consumer flow rates and the flow rate of the countdown stations. The output data is the inlet pressure of each compressor. The standard deviations obtained make it possible to select the best correlations and to assign margins of error to the chosen correlation. The correlation results are used as follows:

• simulation calculation allowing the maximum authorized suction pressure to be available,
• simulation calculation allowing the minimum suction pressure to be available,
• the integral of the difference between the correlated pressure and the minimum pressure multiplied by the volume of water in the upstream network makes it possible to define the flow rate that can be absorbed by the reverse compression in the period of time considered,
• the integral of the difference between the correlated pressure and the maximum pressure multiplied by the volume of water makes it possible to define the flow rate which can be reduced in the reverse compression in the period of time considered,
• by comparing the two previous values to the compressor capacities (minimum and maximum flow rate), the flow rate to be compressed is calculated. He must answer:
  • ∘ if it is detected that there is a need to start another compressor, to increase the flow rate of the compressors in operation, until this need disappears,
  • ∘ if it is detected, the need to stop a compressor, to minimize the flow rate of the compressors in operation, until this need disappears.

Two types of regulation envisaged for the compressor are described below. Flow regulation means that the flow passing through the compressor is constant when the station is operating. On the other hand, it is indeed the suction pressure (for example in a medium pressure network) which triggers the starting and stopping of the compressor when this pressure reaches the limit values set during step 74. Figure 6 represents an example of evolution of the pressure 80 upstream of the compressor and the flow rate 81 of the compressor, in a case where the limit value of starting pressure of the compressor is at 4.2 bars and where the limit value of stopping pressure of the compressor is at 2.5 bars. When the pressure decreases between these two limit values during compressor operation, the controller regulates the compressor operation to have a constant flow rate of 700 Nm ³ /h.

In the case of pressure regulation, the flow rate passing through the station changes so that the suction pressure (for example in a medium pressure network) remains constant. There Figure 7 illustrates an example of evolution of the pressure 80 upstream of the compressor and the flow rate 81 of the compressor with a set pressure value upstream of the compressor of 4 bars, as a function of the flow rate 82 of gas consumed by consumers on the distribution network , the flow rate 83 of gas injected by biomethane producers into the distribution network. We also observe, in Figure 7 , the gas flow 84 supplied by the transport network.

We see, in Figure 7 , that as soon as the consumption rate on the distribution network is lower than the biomethane injection rate, the delivery station stops injecting gas from the transport network and the controller regulates the compressor so that the pressure of the distribution network is constant regardless of variations in consumption on the distribution network.

In the case of the presence of two compressors, a first compressor ensures the operation of the reverse installation up to its operating limit. If necessary, the controller controls the operation of a second compressor to supplement the gas flow passing through the reverse installation.

The two types of regulation have the same objectives, namely to maintain the situation in a stable state for as long as possible, and thus limit the frequent accelerations and declarations of compressors and/or the successive stopping and starting of compressors, or even of control stations. delivery. In current practices, the choice of mode of Control is done manually by an operator based on historical data and his analysis of future events. The algorithmic transcription of the choice for a countdown station is the ratio of proportionality between the pressure and the flow rate, that is to say, the importance of a variation in flow rate in relation to a variation in pressure at the suction of the compression. When the flow variation influences the pressure variation too quickly, the control mode is pressure, especially if there is very little flexibility between the minimum and maximum possible pressures at the compression suction.

• un seuil haut « SH » pour passer de débit à pression (SH réglable), SH à proximité de la pression maximum possible à l'aspiration,
• le seuil haut SH moins epsilon 1 (E1), E1 réglable, SH - E1 seuil pour retourner en mode de régulation en débit, E1 permettant de limiter les changements de mode,
• un seuil bas « SB » pour passer de débit à pression (SB réglable), SB à proximité de la pression minimum possible à l'aspiration,
• le seuil haut SB moins epsilon 2 (E2), E2 réglable, SB - E2 seuil pour retourner en mode de régulation en débit, E2 permettant de limiter les changements de mode.

The present invention allows automatic choice of the regulation mode. If possible flow control is chosen, three control zones are defined. In the center, the flow mode, and at the ends the pressure control. The choice of switching from one mode to another is made at suction pressure thresholds:

• a high threshold “SH” to go from flow to pressure (SH adjustable), SH close to the maximum possible suction pressure,
• the high threshold SH minus epsilon 1 (E1), E1 adjustable, SH - E1 threshold to return to flow regulation mode, E1 allowing mode changes to be limited,
• a low “SB” threshold to go from flow to pressure (adjustable SB), SB close to the minimum possible suction pressure,
• the high threshold SB minus epsilon 2 (E2), E2 adjustable, SB - E2 threshold to return to flow regulation mode, E2 allowing mode changes to be limited.

We describe, below, a method of calculating flow based on modeling of the compression elements and its recycling. These methods exist with certain suppliers, the innovation consists of using its data to back up the main metering, and for diagnosis, all automatically, or even, if it is not necessary to have a transactional metering, in replacement of the position count.

All flow calculation methods are carried out from the upstream pressure (or/and the downstream pressure) and the upstream/downstream pressure differential of the element on which the flow will be modeled. The model comes from mathematical laws of the profession of the element concerned.

For the control valve, the flow coefficient “Cv” given as a function of the opening percentage and the pressure measurements make it possible to recalculate the flow passing through the valve.

For a centrifugal compressor, the dimensions (flow and efficiency coefficients, and the rotation speed of the compressor or the power consumed by the compressor motor) and the pressure measurements make it possible to recalculate the flow passing through a compressor. Another method for a centrifugal compressor is to take the pressure differential across the inlet volute (common term “dp-eye” or “eye dp transmitter”), the model usually being supplied by the compressor supplier.

For a piston compressor, the flow rate is calculated from the dimensions of the piston (compressed volume, dead spaces, rotation speed, and which can take into account the control parameter of the valves if they are controlled) and the pressure measurements allow the compressed flow to be recalculated.

• comparé avec le débit mesuré pour détecter soit un problème sur les organes de transit (compresseur ou vanne de régulation) soit un problème sur le comptage, la comparaison génère une alarme télétransmise pour un diagnostic à distance et
• utilisé automatiquement en remplacement du débit mesuré en cas de défaillance de celui-ci

The calculated flow rates make it possible to determine the flow exported by the station. This flow is then:

• compared with the measured flow to detect either a problem on the transit organs (compressor or regulation valve) or a problem on the metering, the comparison generates an alarm transmitted remotely for remote diagnosis and
• used automatically to replace the measured flow in the event of its failure

• un moyen de détermination du débit transité à travers le rebours permettant de s'affranchir du comptage du poste à l'installation,
• si l'installation de rebours est équipée d'un organe de mesure de débit la traversant, un moyen de détermination du débit transité à travers l'installation de rebours permettant de se substituer automatiquement au comptage de l'installation en cas de défaillance de ce comptage, et permettant de détecter un dysfonctionnement du compresseur ou de la vanne de recyclage (si installée),
• un moyen de détermination du mode de pilotage optimum de la compression entre pression ou débit,
• un système d'analyse permettant à des opérateurs distants ou pas de s'affranchir d'une intervention ou d'évaluer le délai maximum avant intervention.

The present invention also provides:

• a means of determining the flow rate passed through the reverse, making it possible to avoid counting the station at the installation,
• if the backflow installation is equipped with a flow measuring member passing through it, a means of determining the flow rate passed through the backflow installation making it possible to automatically replace the counting of the installation in the event of failure of this counting, and making it possible to detect a malfunction of the compressor or the recycling valve (if installed),
• a means for determining the optimum control mode for compression between pressure or flow,
• an analysis system allowing operators, remote or not, to avoid intervention or to evaluate the maximum time before intervention.

• un moyen d'analyse de qualité de gaz à compresser
• un moyen de communication à distance pour recevoir au moins une valeur instantanée de qualité de gaz captée à distance en amont ou en aval de l'installation de rebours,
• un moyen de prédiction d'évolution de la qualité de gaz dans le réseau en amont de l'installation de rebours, en fonction, au moins, des valeurs de qualité reçues,
• un moyen de détermination d'une valeur limite de qualité de gaz pour l'arrêt d'au moins un compresseur en fonction de la prédiction d'évolution de la qualité.

L'automate commande l'arrêt d'au moins un compresseur lorsque la qualité en entrée de chaque compresseur est inférieure à la valeur limite de qualité déterminée.Everything described above regarding pressure prediction is valid for gas quality prediction. In embodiments, the countdown installation thus comprises:

• a means of analyzing the quality of gas to be compressed
• a means of remote communication for receiving at least one instantaneous gas quality value captured remotely upstream or downstream of the countdown installation,
• a means of predicting changes in gas quality in the network upstream of the reverse installation, based, at least, on the quality values received,
• means for determining a gas quality limit value for stopping at least one compressor based on the prediction of changes in quality.

The controller controls the stopping of at least one compressor when the quality at the input of each compressor is lower than the determined quality limit value.

In embodiments, the countdown installation further comprises a means of determining a loading rate of each compressor as a function of the prediction of the evolution of the quality, the automaton controlling the operation of each compressor to achieve the determined charging rate.

The means for determining the limit value preferably comprises a means for determining the absorption capacity of a non-compliant gas (of low quality) downstream of the backflow installation, capacity making it possible to avoid treatment or to exceed the processing capacities of existing installations.

Below, we give more details on the means of prediction, also called a predictive system.

We recall that the purpose of a predictive system is the statistical prediction of a subsequent state of a system. Such a system is based on the statistical association of past values of input parameters called “predictors” to at least one past output state.

In a learning predictive system, the impact of the predictors on the output state is not initially known and is subject to learning. Learning then consists of assigning to each type of predictor a statistical weighting according to the relevance of the past values of the predictor in the estimation of the known past state of the system.

Such an approach therefore consists of presupposing that the relative impact of all the predictors is unknown or modifiable depending on the learning. Thus, a set of coefficients can evolve over time as new predictor and state values are recorded in the database on which the learning algorithm is based.

The predictions implemented are based on dynamic learning and predictors such as profiles of consumers, suppliers, capacities and response times of compressors of the installation, countdown, inertia and safety. Dynamic learning based on machine learning algorithms, artificial intelligence and/or neural networks, means that the predictive system uses historical data, in particular, for a large number of predictors such as dates and times, pressures observed at different points of the distribution network and triggering and stopping of safety, relaxation, countdowns, consumption, injections. In variants, these data are supplemented by meteorological data. The predictive system continues to collect this data when this predictive system is then used to trigger the operation and shutdown of the timer installation and its components such as valves.

• le profil de consommation ou d'injection de gaz,
• la distance jusqu'à l'installation de rebours, et
• le volume de gaz ou la surface de la section moyenne de canalisation, jusqu'à l'installation de rebours.

When initializing the predictive system, it is provided for example, for each gas consumer and for each gas supplier present on the distribution network:

• the gas consumption or injection profile,
• the distance to the timer installation, and
• the volume of gas or the surface area of the average pipe section, up to the installation of backs.

In addition, for example, we provide the predictive model with the topology of the distribution network, with its branches and the positions of the sensors. We also provide the predictive model with the rise curves in operation of the expansion station and the countdown installation, for example. Finally, for example, we provide the predictive model with the initial setpoint and permanent safety limit pressures for each branch of the distribution network.

During operation of the predictive system, it receives all the pressure, flow, and gas analysis values (depending on needs, one or more constituents of the molar composition or total sulfur, water content, etc.) captured on the distribution network, upstream and downstream of the expansion station and the backflow installation.

On this basis, as well as on calendar data (days of the week, day and month, public holidays) and timetables, as well as on meteorological data and, possibly, agricultural models making it possible to anticipate consumption or injections of gas, the predictive system predicts the evolution of the pressure upstream or downstream of a pressure installation and therefore, depending on a pressure safety value not to be exceeded, the need to start or stop the The countdown installation or, on the contrary, the relaxation station of the transport network.

The predictive system makes it possible to regulate the operation of the countdown installation and the expansion stations so as not to have to stop the countdown or the biomethane producer whose gas quality does not allow it to be transported downstream of the countdown.

The predictive system thus characterizes time constants and safety constants and predicts pressure values and/or pressure setpoint values, for different regimes (injection, consumption, countdown and/or expansion, simultaneous or not) and different moments (in the year, in the week and/or in the day).

For example, on a weak link in the distribution network (that is to say having low inertia or a low volume compared to nominal or maximum consumption), a preventive emergency stop signal is provided for the installation of a countdown as soon as the prediction anticipates a pressure drop below the minimum setpoint value.

In addition, the predictive system determines preferential times for maintenance or inspection stops, on the same basis. These preferential moments are those which minimize a cost function of these stops.

• des prédictions de pression ou de qualité du gaz, dans un horizon de quelques minutes ou de quelques heures et/ou
• des prédictions de valeurs de pression maximales et minimales de consigne à appliquer, de telles valeurs étant déterminées en fonction d'une évolution de pression prédite.

Note that the predictive system can, depending on the embodiments, perform two types of prediction:

• predictions of pressure or gas quality, within a horizon of a few minutes or a few hours and/or
• predictions of maximum and minimum setpoint pressure values to be applied, such values being determined as a function of a predicted pressure evolution.

In the first case, the setpoint and safety values are maintained but the pressure or gas quality prediction is used to determine whether a setpoint value will be exceeded without changing the operating regime of the expansion station. and the installation of countdowns and, if so, whether this overrun will be temporary. If this overrun is not going to be temporary, the operating regime of the expansion station and the countdown installation is modified. Likewise, the prediction of pressure or gas quality is used to determine whether a safety value will be exceeded without modifying the operating regime of the expansion station and the countdown installation and, if so, the operating regime of the expansion station and the countdown installation is modified.

In the second case, the predicted setpoint values are implemented for the automatic operation of the components of the expansion station and the countdown installation. For example, as soon as the pressure in the distribution network becomes, at the expansion station and the backflow installation, lower than the predicted minimum setpoint value, the expansion station is put into operation. On the contrary, as soon as the pressure of the distribution network becomes, at the level of the expansion station and the backflow installation, greater than the predicted maximum setpoint value, the backflow installation is put into operation.

The set value and safety terms can be uniform on the distribution network or, on the contrary, different depending on the portions and branches of the network, these portions and branches being equipped with at least one pressure and/or flow sensor .

• arrêt de sécurité,
• opérations de maintenance réparation, inspection,
• démarrage de l'installation de rebours et
• côté gain, livraison et consommation.

The means 7 for determining limit values (“setpoints”) of pressure for starting or stopping at least one reverse compressor, possibly integrated into the predictive system, as explained above (second case), optimizes a energy and/or economic cost factor, based on the cost or gain linked to the events of:

• safety stop,
• maintenance operations repair, inspection,
• starting the installation of countdown and
• on the earning, delivery and consumption side.

The means 7 for determining pressure limit setpoint values comprises, for this purpose, an energy and/or economic gain and cost calculator.

Claims (14)

1. Backfeeding installation (30), which comprises:

   - at least one compressor (21) for compressing gas from a network (15);

   - a programmable logic controller (25) for controlling the operation of at least one compressor;

   - a remote communication means (9) for receiving at least one instantaneous pressure value captured remotely upstream or downstream of the backfeeding installation;

   - a means (8) for predicting the change in pressure in the network upstream of the backfeeding installation, as a function of, at least, the pressure values received;

   - a means (7) for determining a pressure threshold value for stopping and/or a pressure threshold value for starting at least one compressor as a function of the predicted pressure change,

   the programmable logic controller controlling the stopping or operation of at least one compressor when the pressure at the inlet of each compressor is respectively lower, or higher, than the pressure threshold value that was determined,

   characterised in that the prediction means (8) is configured to predict maximum and minimum pressure setpoint values.
2. Installation (30) according to claim 1, wherein the prediction means (8) utilises a dynamic learning process and profiles of consumers, suppliers and capacities, and response times for the backfeeding installation.
3. Installation (30) according to one of claims 1 or 2, wherein the prediction means (8) utilises artificial intelligence algorithms and/or neural networks.
4. Installation (30) according to one of claims 1 to 3, wherein the prediction means (8) uses historic data, in particular, for a large number of dates and times, of pressures observed at different points in the distribution network and of the starting and stopping of safety, expansion, backfeeding, consumption, injection functions.
5. Installation (30) according to one of claims 1 to 4, wherein the prediction means (8) uses meteorological data.
6. Installation (30) according to one of claims 1 to 5, wherein the prediction means (8) uses the following for each gas consumer and each gas supplier present in the distribution network:

   - the gas consumption or injection profile;

   - the distance up to the backfeeding installation;

   - the volume of gas or the average cross-section area of the line, up to the backfeeding installation.
7. Installation (30) according to one of claims 1 to 6, wherein the prediction means (8) uses the topology of the distribution network, with its branch lines and the positions of the sensors.
8. Installation (30) according to one of claims 1 to 7, wherein the prediction means (8) uses ramp-up curves for the expansion station and backfeeding installation.
9. Installation (30) according to one of claims 1 to 8, which also comprises a means (6) for determining a loading rate to be applied to each compressor (21) as a function of the predicted pressure change, the programmable logic controller (25) controlling the operation of each compressor to achieve the loading rate that was determined.
10. Installation (30) according to one of claims 1 to 9, which also comprises

    - a means (19) for analysing the quality of the gas to be compressed;

    - a remote communication means (9) configured for receiving at least one instantaneous gas quality value captured remotely upstream or downstream of the backfeeding installation;

    - a means (5) for predicting the change in gas quality in the network upstream of the backfeeding installation, as a function of, at least, the quality values received;

    - a means (4) for determining a gas quality threshold value for stopping at least one compressor (21) as a function of the predicted quality change,

    the programmable logic controller (25) controlling the stopping of at least one compressor when the quality at the inlet of each compressor is lower than the quality threshold value that was determined.
11. Installation (30) according to one of claims 1 to 10, which also comprises a means (2) for automatically selecting a flow rate or pressure regulation mode, wherein the regulation mode is a flow rate regulation between two threshold values (SH, SB), and the regulation mode is pressure regulation outside the bounds of these two threshold values.
12. Method (70) for operating a backfeeding installation (30) comprising:

    - at least one compressor (21) for compressing gas from a network (15);

    - a programmable logic controller (25) for controlling the operation of at least one compressor,

    which method is characterised in that it comprises the following steps:

    - a step (71) of receiving, from a remote sensor, at least one instantaneous pressure value captured remotely from the backfeeding installation;

    - a step (73) of predicting the change in pressure in the network upstream of the backfeeding installation, and maximum and minimum pressure setpoint values;

    - a step (74) of determining a pressure threshold value for stopping or starting at least one compressor as a function of the predicted pressure change;

    - a step (75) of respectively stopping or starting the operation of at least one compressor when the pressure at the inlet of each compressor is respectively lower, or higher, than the pressure threshold value that was determined.
13. Method (70) according to claim 12, which also comprises:

    - a step (77) of determining loading rates for the compression to be applied as a function of the predicted pressure change;

    - a step (78) of regulating the operation of each compressor to achieve the loading rate to be applied.
14. Method (70) according to one of claims 12 to 13, which also comprises:

    - a step (71) of receiving, from a remote sensor, at least one instantaneous gas quality value captured remotely from the backfeeding installation;

    - a step (73) of predicting the change in gas quality upstream of the backfeeding installation;

    - a step (74) of determining a gas quality threshold value for stopping each compressor as a function of the predicted quality change;

    - a step (75) of stopping the operation of each compressor when the gas quality at the inlet of each compressor is lower than the quality threshold value that was determined;

    - a step (77) of determining loading rates for the compression to be applied as a function of the predicted gas quality change; and

    - a step (78) of regulating the operation of each compressor to achieve the loading rate to be applied.

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