CN108138760B

CN108138760B - Control system and method for controlling a compression system

Info

Publication number: CN108138760B
Application number: CN201680051524.0A
Authority: CN
Inventors: S·尼曼; S·海莫宁; H·劳里拉
Original assignee: SARLIN Oy AB
Current assignee: SARLIN Oy AB
Priority date: 2015-08-14
Filing date: 2016-06-30
Publication date: 2020-09-25
Anticipated expiration: 2036-06-30
Also published as: EP3334934A4; EP3334934B1; CN108138760A; PL3334934T3; ES2900024T3; EP3334934A1; WO2017029427A1

Abstract

A control system and method for controlling a compression system, the compression system comprising: a compressor and its controller; a secondary treatment device for treating the medium delivered from the compressor; a pipe system for delivering a fluid medium to a consumption site, the control system comprising a control unit comprising: a data processing system controlling the compression system; a user interface including an associated display; and a transmission device for transmitting control data among the control unit, the controller and the pressure sensor. The compression system may have a plurality of adjustment values for determining demand for the fluid medium, change of direction and rate of change of the fluid medium, the compressor specific adjustment values being based on parameters given from the user interface, the adjustment values being converted into network delivery requests or network pressure settings or compressor specific pressure settings, the control system being adapted to convert the network delivery requests or network pressure settings or compressor specific pressure settings into compressor specific control requests via direct control data, pressure settings or pressure data items of the compressor.

Description

Control system and method for controlling a compression system

Technical Field

The object of the invention is a system for controlling a compression system of a fluid medium and a method for controlling a compression system.

Background

In industrialised countries, approximately 10% of the electrical energy consumed by the industry is spent on the production of compressed air. In addition, compressed air is a critical production factor, and therefore quality problems occurring in compressed air are in many cases economically significant. The inefficient use of compressed air has been found to be a significant problem in many countries.

In a compression system of a compressed air network, a compressor is used to generate compressed air which is conducted via a cooler and a pressure tank to a secondary treatment unit provided with a filter and a dryer and a second pressure tank from which the compressed air is supplied to a consumption site. The compressors are controlled by means of controllers which are connected via a data communication bus to a control computer controlling the system. Further connected to the control computer are, for example, pressure sensors, and the data obtained from these sensors are used for the control of the system.

The specification WO91/06762 discloses a compressor control device of this type which may be connected to a computer. Via a data communication bus, several compressors may be connected to the computer. A single controller may control the modes of operation of a single compressor, which are on/off line, modulated operation, and de-rated operation. In the WO91/06762 specification, the controllers of the compressors may be controlled individually by means of signals obtained from a computer. In addition, the device comprises a graphical display (such as an LED display) on which e.g. controller parameters can be presented, and an operator of the device can operate the device via a user interface by pressing different switches.

In order to save energy when producing compressed air, various methods have been developed. The most typical of these solutions is a standard controller provided by the compressor manufacturer and having its own control program that cannot be customized to suit other manufacturers' compressors and does not include verification of control efficiency. In addition, a partially modular approach has been developed that is customizable for several compressor types and allows for the connection of several pressure sensors.

There are also measurement methods that can be used to determine the energy saving benefits achieved by the control. However, these measurement methods have a single operational nature and must be repeated regularly if the aim is to ensure continuous high-quality execution. The price of a customizable solution is high due to, among other things, the large amount of programming effort required. In these cases, the plants must be built in small production series, and they are therefore expensive.

Most (up to 80%) of the maintenance visits associated with the control system may be due to malfunctions due to misuse. This is because current control systems are stand-alone systems that are not maintained after introduction, except in sporadic cases. When users are replaced, the training they have received is no longer useful. The actual compressed air system to be controlled has been developed over many years and the control system does not necessarily adapt to the changed situation. This leads to the following situation: over time, even a well-functioning control system does not necessarily achieve its objectives.

The US4502842 specification discloses a system consisting of a plurality of compressors, which can be preset to function in different situations, for example in such a way that only some of the compressors are operated or at reduced power. The specification US4526513 proposes another system for controlling a compressor system.

The systems known in the prior art do not allow to achieve the best possible energy efficiency, but instead the compressors of them are often driven in ranges where the efficiency ratio of the compressor and/or of the whole system is not good.

Disclosure of Invention

The object of the present invention is to achieve a new type of control system and a new type of control method in order to enable the operation of pneumatic systems and equivalent to be made more efficient on a large scale at reasonable costs and with limited human resources. Details of the features of the system of the invention are given in the following claims.

In the system according to the invention, one or more compressors and associated secondary treatment devices connected to one or more compressed air networks or equivalent are controlled and monitored. The system of the invention is a system for controlling at least one compression system of a fluid medium. The compression system includes: a compressor and its associated controller for compressing a fluid medium; a secondary treatment device for treating the medium delivered from the compressor; and a piping system for conducting the fluid medium to the consumption site. The control system includes a control unit comprising: a data processing system for controlling the compression system; a user interface including a display associated therewith; and transmission means for transmitting control data between the control unit, the controller and the pressure sensor. A control mode specific to the type of compressor may be selected in the compression system, which determines the adjustment value to be used. The adjustment value determines the demand for the fluid medium, the change in direction of the fluid medium, and the rate of change. The parameters given from the user interface may act on the adjustment value. The control system is adapted to convert the adjustment value into a delivery request and a control request of the compressor based on the regulation mode selected for the compressor. The selection of the control and regulation modes of the compressor is made from the user interface of the control system.

By means of the system according to the invention, it is possible to operate variable displacement compressors (variable delivery compressors) within a good compressor specific efficiency range, thereby achieving the best possible energy efficiency. By means of the system according to the invention, the range of operating compressors can be limited to a specific compressor. In addition to this, the measurement data can be used to control the delivery rate of the compressor.

Drawings

The invention will be described in more detail hereinafter by means of some embodiments with reference to the accompanying drawings, in which:

FIG. 1 presents a compression system according to an embodiment of the present invention;

FIG. 2 presents the operation of a system according to an embodiment of the present invention;

3A-3D present as flow charts the operation of a control mode and a regulation mode of a compressor according to some embodiments of the present invention;

FIGS. 4A-4C present definitions of network delivery requests according to embodiments of the present invention;

FIG. 5 presents a definition of a compressor delivery request according to an embodiment of the present invention;

fig. 6 presents an example of the operation of the control mode and the regulation mode of the compressor according to the embodiment of the present invention.

Detailed Description

In the following, the invention will be described in more detail by means of an example of embodiment thereof with reference to fig. 1, which fig. 1 presents a block diagram of a pneumatic system according to the invention comprising a control unit 3.

The pneumatic system according to the embodiment of the invention presented in fig. 1 comprises two

compressed air networks

1, 2 which are connected to a control system controlling them. The first network 1 includes: six compressors C1-C6 with their controls A1-A6; a pressure tank 11 connected to three compressors C2-C4; four secondary processing units 12-15; a consumption site 16; and piping 17-19 for their interconnection. The second network 2 correspondingly comprises one compressor C7 with its controller a7, secondary process units 21, consumption sites 22 and interconnecting piping 23 for them.

In addition, both networks are provided with: pressure sensors PI1-PI5, wherein PI1 is connected to the conduit 17 between the compressor C1 and the secondary treatment unit 12, PI2 is connected to the pressure tank 11, PI3 is connected to the conduit 19 between the compressors C5, C6 and the

secondary treatment units

14, 15, PI3 and PI4 are connected to the consumption site 16, and PI5 is connected to the conduit 23 between the compressor C7 and the secondary treatment unit 21 and to the consumption site 22; and a pneumatic station controller AS1-AS3, wherein AS1 is connected to sensors PI2, PI4, PI1 and secondary processing unit 13, AS2 is connected to controllers a5, a6 and sensor PI3, and AS3 is connected to sensor PI 5.

The above described controllers and sensors may be connected to a serial port 33 of the control unit 3, for example via three serial communication buses 30-32 common to both devices, and also to a control computer 34 comprising a display and a user interface 35. The controllers, sensors, and other components of the system may also be connected using some other wireless or wired data communication bus or data communication method. The user interface is provided with a user interface program and the control computer is provided with a group control program and a controller unit.

Via the user interface 35, a user may observe the operation of the pneumatic system, configure the control and monitoring system, and output reports related to the operation of the system. The control program regulates and controls the pneumatic system via the pneumatic station controller and the compressor controller on the basis of information obtained by means of the data communication means and the program and instructions given by the user.

The pneumatic station controller AS1-AS3 reads data specific to the pneumatic station, such AS pressure and alarm data, from the pneumatic system. The compressor controllers A1-A7 read data related to the compressor and control commands sent by the control program via the data communication bus 30-32 and execute commands such as start, stop, and load.

The number of compressors may be provided as a parameter to the group control program. There is no need to change the control program in any way when a compressor is added or removed. This is because, as far as the compressors are concerned, the program is constructed according to a modular design in such a way that each compressor C1-C7 is an embodiment of its class, which is used or deactivated depending on the given parameters.

Each compressor C1-C7 may be configured as any compressor type via the user interface 35 by virtue of parameters. Thus, the control system need not be modified at all when the control system is first configured or when the individual compressor type is later changed. This is due to the fact that: the above-described embodiments of the compressor class can be configured as any base compressor type by means of parameters. These are for example constant speed control, frequency converter drive control or turbo compressor control.

A required number of pressure sensors PI1-PI5 may be connected to the control system to read the delivery pressure of each compressor and the desired network pressure. This makes it easier to control the compressor and gives a general view of the state of the pneumatic network. Any one of the pressure sensors may be configured to indicate the delivery pressure of any one of the compressors, and any one of the pressure sensors may be configured to serve as a control pressure for the entire system. The addition or removal of the pressure sensor does not involve any changes in the control program.

Each pressure data item may also contain information about how large a volume it belongs to and what the rate of change of the pressure is. Based on these data, the exact change in the amount of compressed air can be calculated for the volume being considered. The real-time actual consumption of compressed air is obtained by calculating the change in air volume for each volume and combining this information with data relating to the status of all compressors. The method obviously improves the control accuracy and the reaction capability.

Also, other measuring or controllable devices may be connected to the control system. These may be, for example, dew point, heat rate or flow rate measurements, valves, dryers, fans, ventilation flaps or pump controls. The additional measurements and the properties of the additional devices are defined by parameters. The addition or removal of additional measurements and additional devices does not involve any changes in the application software.

The control system may control and monitor a plurality of individual

pneumatic systems

1, 2. This makes it possible to select any of the pressure sensors PI1-PI5 connected to the system as a control pressure sensor for each compressor C1-C7, and in addition, any of the compressors can be set via a user interface to be controlled according to the pressure sensor value, which is selected according to the individual pressure setting.

Thus, the operation of the compressor can be controlled with the system for controlling a compression system according to the present invention. In the compression system according to the invention, the mode of controlling and regulating the specific delivery of the compressor can be selected from a user interface. Based on the selections made from the user interface, the control of the delivery of the compressor may be based on a delivery reference value calculated from the network delivery request, or directly based on a network pressure setting or a compressor specific pressure setting as presented in fig. 3A.

A mode for adjusting the compressor is selected for a particular compressor from a user interface. How the regulation of the compressor operates depends on which control mode is selected for the compressor. The regulation of the compressor is achieved with direct adjustment (e.g. by changing the rotational speed) or by changing the pressure setting or by changing the delivery pressure reading of the compressor.

If the delivery request is selected as the control mode of the compressor, then as in the graph in fig. 3B, the network delivery request is an adjustment value that determines the air demand or, more generally, the demand for fluid medium, the change in direction of the fluid medium and the rate of change. The determination of network delivery requests (0-100%) according to one embodiment of the invention is depicted in fig. 4A-4C. As presented in fig. 3B, a regulation mode for the compressor is selected from the user interface. If a direct reference (e.g., speed) is selected as the method of regulating the compressor, the delivery request of the compressor is scaled to the format required by the compressor. If the pressure setting is selected as the regulation mode, the network delivery request is converted into a compressor delivery request and further into a pressure setting taking into account the restrictions given from the user interface. In this case, the rate of adjustment may first be checked and a new pressure setting may be calculated based on the magnitude of the compressor delivery request, its derivative, and the value and derivative of the delivery pressure sensor of the compressor. In addition, the pressure difference over the secondary processing unit can be taken into account if the compressor's own pressure sensor is not on the network side. If the pressure data item is selected as the regulation mode, a rate check may be performed first and the same value as the pressure setting of the compressor may be provided to the compressor for the pressure transmitter signal. According to the delivery request, a value larger than the above-described value may be set to the value if smaller delivery is required, and a smaller value may be set if larger delivery is required. The determination of the delivery request of the compressor according to one embodiment is presented in more detail in fig. 5 and 6.

If the compressor control mode is a network pressure setting, as in the graph of FIG. 3C, the network pressure setting is an adjustment value, and the demand for fluid medium, the change in direction of the fluid medium, and the rate of change are determined by comparing the adjustment value to the reading of the control pressure sensor. The compressor adjustment mode is selected from the user interface, which adjustment mode can be a direct reference, a pressure setting or a pressure data item in the case currently considered. The network pressure setting may for example be converted into a compressor pressure setting taking into account the pressure loss due to the secondary treatment of the compressed air. If the direct reference is used as a compressor regulation mode in case of a network pressure setting, a check of the regulation rate may be performed, how much the network pressure data item differs from the network pressure setting may be calculated, and the direct reference may be changed based on this information. With a slow adjustment rate, the changes are distributed to the desired time period, and the direct reference is also updated between checks of the adjustment. If the pressure setting is used as a mode to regulate the compressor, a check to adjust the rate may be performed and the network pressure setting may be provided to the compressor. If the compressor's own sensor is not on the network side, the setting can be corrected by the pressure difference over the secondary processing unit. If the pressure data item is used as a mode to regulate the compressor, a check of the regulation rate may be performed and it may be calculated how much the network pressure data item differs from the network pressure setting. The pressure data item to be supplied as a pressure transmitter signal to the compressor can be corrected if necessary.

If the compressor control mode is a compressor specific pressure setting, then the same as in the graph of fig. 3D, the compressor specific pressure setting is an adjustment value that is compared to the reading of the control pressure sensor to determine the fluid medium demand, the change in direction of the fluid medium, and the rate of change. The compressor adjustment mode is selected from the user interface, which adjustment mode can be a direct reference, a pressure setting or a pressure data item in the case currently considered. If a direct reference is used as the regulation mode in case of a compressor specific pressure setting, a check of the adjustment rate may be performed, it may be calculated how much the compressor pressure data item differs from the compressor specific pressure setting, and the direct reference may be changed based on this information. With a slow adjustment rate, the changes are distributed to the desired time period, and the direct reference is also updated between checks of the adjustment. If the pressure setting is used as a mode to regulate the compressor, a compressor specific pressure setting is provided to the compressor. If the pressure data item is used as a mode for regulating the compressor, a check of the regulation rate can be performed and it can be calculated how much the compressor pressure data item differs from the compressor specific pressure setting. The pressure data item to be supplied as a pressure transmitter signal to the compressor can be corrected if necessary.

Fig. 4B depicts how the determination of the network delivery request progresses. If the network pressure is close to the setting (i.e., within limits closer to the setting), the rate of change of the network pressure is checked. If the rate of change is large, the change is slowed down by changing the network delivery request quickly, and if the rate of change is small, the network delivery request is changed slowly. The average change in the network pressure may be used to evaluate the rate of change of the network pressure, and a setting for the rate of change may be used as a parameter when examining the rate of change, the setting being intended for situations where the network pressure is close to the setting (i.e., within limits closer to the setting). If the network pressure is further away from the setting (i.e., outside the limit values closer to the setting but within the limit values further away from the setting), the rate of change of the network pressure is checked. If the rate of change is large, the change is slowed by rapidly changing network delivery requests, and if the rate of change is small, the network delivery requests are slowly changed. The average change in the network pressure may be used to evaluate the rate of change of the network pressure, and the setting for the rate of change may be used as a parameter when examining the rate of change, which is intended for situations where the network pressure is far away from the setting (i.e. outside the limit values closer to the setting but within the limit values further away from the setting). If the network pressure is far away from the setting (i.e. outside the limit values that are further away from the setting), the network delivery request is changed quickly. The rate of change setting may be used as a parameter when checking the rate of change, the setting being intended for situations where the network pressure is far away from the setting (i.e. outside the limit values that are further away from the setting).

Fig. 4C depicts how the determination of the network delivery request may progress further. After performing the above process, it may be checked whether there is a variation in the number of compressors required to deliver air. If the number of required compressors changes, the increased/decreased compressor capacity can be compensated for by changing the network delivery request. If the number is unchanged, no further steps are required. The number of compressors delivering air and their delivery (which are known to the system) can be used to evaluate the number of compressors required.

Fig. 5 is a graph presenting the determination of a compressor delivery request in the context of one embodiment of the present invention. First, a delivery request of the compressor is determined according to a network delivery request. The limits of the compressor adjustment range may, for example, affect this determination. After this, the efficiency ratio of the compressor is checked and the delivery request of the compressor is changed in order to be as efficient as possible from the viewpoint of the efficiency ratio of the compressor. In evaluating the compressor efficiency ratio, the efficiency ratio of the currently considered compressor and, for example, the efficiency curve of the compressor can be used.

Fig. 6 presents an example according to an embodiment of the invention, wherein the compressor control mode is a delivery request and the compressor regulation mode is a pressure setting. The set point may be selected via a user interface of the control system and a delivery request, a network pressure setting or a compressor specific pressure setting may be selected as a control mode for the compressor. Among these, a delivery request is selected for this example. A direct delivery reference, pressure setting or delivery pressure reading may be selected as a regulation mode for the compressor. In this example, the pressure setting is selected as a mode for regulating the compressor.

In the embodiment of fig. 6, the network delivery request is first determined (0-100%). The change in direction and rate of change of the network pressure, the difference from the set pressure, and the rate of change selected from the user interface all affect the calculation. After this, a delivery request for the compressor is determined (0-100%). The adjustment range, which is adjusted via the user interface and is available for the compressor, is taken into account when determining the compressor delivery request. Finally, a pressure setting for the compressor is determined, and the efficiency curve of the compressor can be taken into account here, for example, in such a way that the compressor is always used with the best possible efficiency ratio. In determining the pressure setting of the compressor, the adjustment range of the compressor, the delivery request value and the magnitude of the change in the value, and the value of the delivery pressure sensor of the compressor are taken into account, and in addition, the differential pressure over the secondary processing unit is taken into account if the delivery pressure sensor of the compressor itself is not on the network side.

The user can optimize the operation of the entire pneumatic system by selecting the control mode and the regulation mode of the compressor and utilizing the parameters of the selected regulation values. The control system is adapted to the control and delivery regulation of all known compressor types. In the system according to the invention there is no limit on how many variable displacement compressors can be controlled and regulated together. This enables the best possible energy saving benefit to be achieved.

In the controls known from the prior art, the regulating range of the compressor remains fixed. In practice, however, the adjustment ranges of the compressors are of different sizes and therefore do not use the entire adjustment range of the compressors in the solutions known from the prior art, or the desired machine cannot be selected to always operate with the best efficiency ratio. This results in unnecessary consumption of energy.

In the solution of the invention, the direction of the network air demand and its amount of change can be calculated when converting the network adjustment value into a delivery request for a variable displacement compressor. The variation is distributed to the variable displacement compressors. After this, a check is made as to whether the requirements can be corrected in a more energy-efficient direction, for example by means of an efficiency curve of the compressor.

The effect of the efficiency curve can be taken into account if one or more of the compressors have a better efficiency ratio with a larger delivery and some of the compressors have a better efficiency ratio with a smaller delivery. The effect of the efficiency curve can also be taken into account if some compressors have better efficiency ratios with smaller deliveries and, even if the efficiency ratio of all the machines would be better with smaller deliveries, their capacity is significantly greater than that of the other compressors. The effect of the efficiency curve can also be taken into account if a certain compressor has a better efficiency ratio at a larger delivery and, even if the efficiency ratio of all the machines is to be better at a larger delivery, its capacity is significantly greater than the other compressors.

In the solution according to the invention it is also possible to de-load and stop the compressor. In this case, the wasted capacity of the variable displacement compressor is calculated and, if necessary, the small compressor is turned off so that the variable displacement compressor operates at a greater delivery.

The controller known in the art may have a load relief limit and a load limit for the compressor. Normally, in the solutions known from the prior art, a plurality of variable displacement compressors are operated with minimum delivery, in which case the pressure rises very slowly or not at all. The next compressor is de-loaded only when the de-loading limit is reached. In such prior art solutions, the variable displacement compressor is driven for a long period of time with a poor efficiency ratio.

In the solution according to one embodiment of the invention, the compressors to be subsequently de-loaded in turn are identified. In addition to this, the wasted capacity of the variable displacement compressor is calculated. The capacity of the compressor to be de-loaded is not included in the calculation. A safety factor given from the user interface or automatically calculated is inferred from the wasted capacity, thereby obtaining a calculated wasted capacity. The delivery of the compressor to be de-loaded at the moment of current consideration is inferred from the calculated wasted capacity. If the calculated result is positive, the compressor is de-loaded.

The advantage of this solution is that the unloading of the next compressor is performed significantly earlier and the driving of the variable displacement compressor in the range of low efficiency is reduced compared to the solutions known from the prior art. Continuous loading and unloading of the machine can be avoided using a safety margin. If the consumption fluctuates, hysteresis can be used, which reduces "unnecessary" on/off switching.

FIG. 2 presents an example of a compressor derating scenario for the operation of a system according to an embodiment of the present invention.

The regions marked in fig. 2 are defined as follows:

1 ═ running compressor

2 ═ stopped compressor

3-compressor to be subsequently de-loaded

4-operating variable displacement compressor

In the embodiment presented in fig. 2, the compressor that is next to be de-loaded in turn is identified (i.e., compressor 2 in this case, since it has the lowest priority (═ 4)). The next compressor to be relieved is now 50% by 80m3/min to 40m 3/min.

After this, the wasted capacity of the running variable displacement compressor (region 4) is calculated: (100% -75%) 100m3/min + (100% -75%) 80m 3/min-45 m 3/min.

A safety factor is inferred from the wasted capacity, thereby obtaining a calculated wasted capacity. For example, if the safety factor is 4m3/min, the calculated wasted capacity is 45m 3/min-4 m 3/min-41 m 3/min.

The delivery of the compressor to be de-loaded is inferred from the calculated wasted capacity and if the end result is positive, the compressor is de-loaded. Thus, for example, if the safety factor is 4m3/min, the end result achieved is: 45m 3/min-4 m 3/min-40 m 3/min-1 m 3/min. In other words, the compressor is de-loaded with the safety factor currently considered. Thus, for example, if the safety factor is 6m3/min, the end result achieved is: 45m 3/min-6 m 3/min-40 m 3/min-1 m 3/min. With this safety factor, the compressor is not de-loaded.

The compressor to be relieved of load may also be a fixed delivery or some other type of compressor. All compressors capable of operating at part load (e.g., frequency converter driven or turbo compressors, multi-stroke piston compressors, etc.) are considered variable displacement compressors.

In the solution according to the invention, the adjustment range of the variable displacement compressor can be set from a user interface. In this way, the compressor can be operated at an optimum efficiency ratio and the turbocompressor discharge can be avoided.

The relief and loading limits of the pressure are set in some central controllers known in the art. It is also possible that the central controller has pressure setting and loading limits or setting and unloading limits. If the controller is also capable of driving a variable displacement compressor, the system also often has a pressure setting for the compressor. However, in the combinations known in the prior art, it is not taken into account how the variable displacement compressor and the deloading-loading compressor are arranged to operate together. The problem occurs in particular in the following cases: the base load operates with the variable displacement compressor and there are times when: if the capacity of the compressor is ended halfway, the de-loaded compressor is put into service to support pressure delivery. In this case, it generally happens that the variable displacement compressor operates at a high or medium to high pressure level when there is sufficient capacity. At the end of the capacity, the pressure is allowed to drop, and when the pressure has dropped sufficiently, the support compressor is started.

In the solution of the invention, the deloading setting limit and the loading setting limit can be set for the central controller in such a way that the setting limit of the loader is very close to the loading limit. The range between the deloading set limit and the loading set limit may also be automatically calculated by studying the pressure driven by a single variable displacement compressor and its fluctuation range. One advantage of this solution is that the pressure level is lower and energy can be saved when the variable displacement compressor is operated alone.

In the solutions known from the prior art, the compressor generally has three settings in the central control: relief pressure, loading pressure, and set pressure. In some compressors, dumping the excess air begins when they are driven with the smallest possible delivery. Dumping excess air wastes significantly more power than when operating at minimum delivery and no outlet valve is opened. In some compressed air networks, where the consumption fluctuates significantly, there are very many situations where the operation is at the minimum delivery limit.

In the solution according to the invention, it is possible to allow exceeding the normal pressure setting (e.g. in these types of cases). In this case, for example, the turbocompressor is allowed to operate at a higher pressure than specified by the pressure setting. In this case, the turbine is not dumped, but the discharge valve remains closed. This achieves better energy efficiency.

In the solution according to the invention, different deloading limits can be added for deloading-loading compressors and for variable displacement compressors. The limit of the variable displacement compressor may be set higher than the limit of the deloading-loading compressor. Thus, in this case, the pressure is allowed to rise slightly in the network before the compressor is allowed to dump. The limit may be set, for example, via a user interface. By using the above solution, the compressor dump is reduced at minimum delivery, thereby reducing the need for power losses.

The further conversion of the delivery request to the control request for the compressor (i.e. the adjustment of the delivery of the variable displacement compressor) can be made in a number of ways in the solution of the invention (e.g. with direct reference from resolution per minute, delivery percentage or attitude of the suction vanes). The adjustment of the delivery of the variable displacement compressor may be made with a change in pressure setting, automatically or by simulating a network pressure data item along with the pressure setting. These methods are applicable to all compressor types regardless of model and fabrication.

In the system of the present invention, an adjustment value may be calculated for the compressor that specifies a desired delivery or pressure level of the compressor and a desired compressor drive sensor that may be provided to the compressor. By means of this, either the rotational speed or the IVG position, the pressure setting or the simulated network pressure data item are calculated as values to be supplied to the compressor. After this, the compressor power or sensor pressure is measured. Based on the measurement data, the value to be supplied to the compressor is corrected in such a way that the setpoint is reached. In this way, compressors controlled with different control modes can be controlled together in a uniform manner. Also, the compressor can be parameterized easily from the user interface.

By means of the system of the invention, it is possible to control a plurality of different plants with a plurality of different compressed air networks or air networks with the same controller. In this case, the controller of the system of the present invention may have set points, user interfaces, and control logic for a very large number of points. A computer can be reserved for the center that can process the data fast enough and from which the control can be formed. The system may also be configured in such a way that: so that interruptions in the computer network do not prevent the production of compressed air. In this way, the platform of the server for the enterprise group can be connected to the control apparatus, and a separate system is not required. This results in cost savings and easier group-by-group update management. Likewise, plant-specific or pneumatic network-specific comparisons may then be made.

In one embodiment of the system of the present invention, a compressed air network may be controlled in multiple sections. In this case, a compressed air network is divided into a plurality of "virtual networks" in terms of its control. These parts of the compressed air network are controlled as separate entities. In this case, the pressure reduction of the faster part of the network can be taken into account and can be reacted to in the best possible way.

The system of the present invention may have an emergency sequence if any of the selected compressors are inoperable. In this case, the larger compressor, which is running as a base load, is placed in the list of choices to generate an emergency sequence when the compressor is stopped or not delivering air for some unforeseen reason. Larger replacement compressors are placed in emergency sequences so that they are put into service earlier. The use of the contingency sequence may be automatically interrupted upon detection of a return of the system to a normal state. The operator may initiate and interrupt the use of the emergency sequence from the user interface, or the initiation may be automatic.

By means of the emergency sequence of the system according to the invention, a compressor which normally does not operate as base load can also be used as a compressor operating as base load in the event of a compressor failure, in order to replace a failed or stalled compressor which normally operates as base load. In this case, a more uniform pressure is achieved in operation after the failure of the larger compressor and after the failure. In this case, it is also possible to calculate the lowest operating pressure and to continuously save energy during normal operation.

In one embodiment of the invention, the compressor may be run hotter in a timed manner, depending on the settings given in the user interface or by direct selection from the user interface. After that, the compressor returns to the normal automatic drive. Dedicated operating states (in addition to normal states, also local, automatic, manual states) can be built into the central controller for the purpose of hotter operation. The compressors can be individually switched to the state currently considered, for example in a timed manner or via a user interface. The compressors are moved in front of other compressors in terms of priority, becoming very easily driven compressors. The compressor may return to an automatic or some other previous state from the currently considered state based on the compressor oil temperature (or other measurement) running through all stages/states or in a timed manner. Finally, the compressor stops and shuts down when it is no longer at the top of the priority list.

With the above-described solution, manual work is reduced when the backup compressor can be run hotter in a controlled manner automatically and it can be ensured that the compressor runs definitely hotter and all the stages/states required for proper implementation can be achieved. However, the backup compressor is not used for unnecessarily long periods.

In one embodiment of the invention, a special point may exist in the network and the system may take this special point into account. Thus, if there is a certain point of importance in the network, the pressure at that location can be monitored and the location can be set to a particular point in the system. If the pressure is reduced, the setting for the delivery end can be increased. Thus, for most of the time, the delivery end pressure may be lower and when a higher delivery end pressure is required, the pressure may be raised to a desired level. In this way, an unnecessarily high pressure is generated without the compressor. Also, the effect of consumption spikes on the pressure level at a particular point can be detected more quickly, and the network pressure can be kept low when consumption spikes do not occur in the network.

In this embodiment, additional sensors may be added to the consumption site and/or measurements available in the network may be used. There may also be a setting of a desired minimum pressure for a particular point. In addition, there may also be settings for how much network pressure may drop or rise depending on the particular point and the parameters of the controller. The settings may be selected by an operator. The compressor can be controlled and the network pressure level raised according to a given setting.

In one embodiment of the invention, the higher pressure network may be supported by the lower pressure network if desired. In this embodiment, the system may identify a pressure drop in the higher pressure network. Support of the second network may also be initiated for another reason. In the solution of this embodiment, a second sequence is selected in the lower pressure network, in which sequence the pressure level of the lower pressure network is higher. After this, it is verified that the pressure rises in the lower pressure network to become higher than the pressure of the higher pressure network. After this, the valve is opened to support the higher pressure network. When verification based on measurements can be performed, a return to normal sequence may be made. The return may also be effected from the user interface.

In the system according to the invention, maximum and minimum pressure limits can be set for each compressor and for the pneumatic system. When these values are exceeded, the control of the compressors is switched to their own control system. The sequence of starting and loading the compressor is determined by the operational sequence list.

The compressor may be arranged to operate according to a plurality of operational sequences as required. This is possible because each independent sequence of operations is an implementation of its class, which can be used or deactivated by changing the program parameters that determine the number of implementations. Thus, no changes at all need to be made to the program when adding or removing operational sequences.

The manner in which the sequence of operations is changed is selected by changing a control parameter. The operational sequence may be changed based on, for example, a week, a stop of the compressor, or an automatic setting. The automatic change is based on a continuous calculation of the required idling power of all possible compressor combinations, which in combination with an observation of the required compressors to be kept active and a free selection of observation intervals results in an automatic selection of the most efficient operation sequence possible.

In one embodiment of the present invention, if there is enough compressor, the compressor can be rotated by limiting the start-up of the compressor. For example, when large motors are involved, start-up may be limited to 2 times per hour, for example. If three 10 minute cycles per hour are required, the first 2 cycles are run by one compressor and the last cycle by another compressor. This can reduce excessive idling. The rules may be compressor specific and they may be set, for example, with a central controller.

The method of starting and stopping the compressor may be selected via a user interface. These methods are start and stop with continuous signals or pulses and the operation is stopped or stopped based on the allowed number of starts.

The start-up, load and unload delays for each compressor can be adjusted individually. This allows the correct operation of the method in any case, regardless of the dynamics of the pneumatic system itself.

The compressor controller reads information from the compressor and sends information to the control program, reads control commands from the group control program, and executes the commands according to its own control program while also monitoring the validity of the commands and the conditions of the data communication bus and the program. In existing solutions, even a single non-standard compressor model to be incorporated under the control system requires relatively extensive modifications to the control program. This problem is now limited to the modification of simple compressor controller programs. When the solution is successful, even this modification work is reduced, since this will easily form a library of compressor controller programs.

The control program may continuously calculate the total output and power input of the pneumatic system. These data may be stored on mass storage media. In the user interface, these data may be presented in the same graph so that they can be viewed in a graphical form from moment to moment. In addition, the user interface calculates the average consumption and power during the selected time period. Also, the dots of the map may be printed to the file at desired time intervals. The resulting report allows to verify that the actual benefit generated by the control system can be performed even with continuous measurements over a long period of time.

The information received by the control program via the data communication means regarding the compressor status and pressure values is continuously stored on a mass storage medium which may be in the control computer. The operating state and the pressure level of the compressor can be presented in the same graph, so that they can be viewed in a graphical form from moment to moment. This enables the operation of the pneumatic system to be analysed in real time or thereafter.

The basic architecture of the method allows for the use of any manufacturer's device in the compressor controller. This makes it possible to use the invention in many situations where it was not possible before.

When a disturbance (e.g., a connection failure) occurs in any part of the system, the compressor controller switches control to the compressor's own control system. This ensures a trouble-free production of compressed air in almost all cases.

The operation of the compressor controller may be tested by means of the group controller or any device capable of writing run and load commands to the controller. This is achieved by the structure of the controller program, in which the external interface can be kept as simple and standard as possible, regardless of the type and model of the compressor. Only the run/stop command and the required loading factor are written through the interface.

It is obvious to the person skilled in the art that different embodiments of the invention are not exclusively limited to the examples described above, but that they may be varied within the scope of the claims presented below.

Claims

1. A control system for controlling a compression system, the compression system comprising: a compressor (C1-C7) and its controller (A1-A7), said compressor (C1-C7) and its controller (A1-A7) being used for compressing a fluid medium; a secondary treatment device for treating the fluid medium delivered from the compressor; and a pipe system (17-19, 23), the pipe system (17-19, 23) being adapted to conduct the fluid medium to a consumption site (16, 22), the control system comprising a control unit (3), the control unit (3) comprising: a data processing system (34), the data processing system (34) for controlling the compression system; a user interface (35), the user interface (35) including a display associated therewith; and transmission means for transmitting control data between the control unit, the controller and the pressure sensor,

it is characterized in that the preparation method is characterized in that,

the compression system having at least one compressor-specific adjustment value determining a demand for a delivery amount of the fluid medium, a change of direction of the fluid medium and a rate of change of the demand for the delivery amount of the fluid medium, wherein a control mode can be selected from the user interface (35) for the compressor, the control mode determining the adjustment value to be used,

wherein the control of the delivery of the compressor is based on a delivery reference value of a delivery volume calculated from a network delivery request, or directly on a network pressure setting or a compressor specific pressure setting,

wherein the control system is adapted to convert the network delivery request or the network pressure setting or the compressor specific pressure setting into a compressor specific control request via direct control data, pressure setting or pressure data items of the compressor.

2. The control system according to claim 1, characterized in that the compressor has a limit to the adjustment range of the delivery volume, said limit being adapted to be determined from the user interface.

3. Control system according to claim 1 or 2, characterized in that the control system is adapted to convert the network delivery request or the network pressure setting into a delivery request to a variable displacement compressor based on an allowed adjustment range of the delivery amount of the compressor and/or based on an efficiency curve of the compressor.

4. A control system according to claim 3, characterised in that the control system is adapted to take into account the effect of the efficiency curve if one or more of the compressors is delivered with a substantially larger delivery having a better efficiency ratio and there is also a better efficiency ratio of the compressors delivered with a substantially smaller delivery.

5. Control system according to claim 1, characterized in that the control system is adapted to convert the delivery request further into a control request for the compressor using a direct reference derived from the rotational speed, a reference derived from a percentage of the delivered amount of the compressor or a reference derived from the attitude of the suction vanes.

6. A control system according to claim 5, characterized in that the control system is adapted to calculate, for a compressor, an adjustment value for what delivery amount the compressor is expected to deliver, or to give a pressure level and a sensor that the compressor is expected to run,

the control system is further adapted to calculate the rotational speed or the attitude of the suction vanes, a pressure setting or a simulated network pressure data item for sending to the compressor as a control request.

7. Control system according to claim 1, characterized in that the control system is further adapted to measure the power of the compressor or to read the pressure value measured by a sensor and to correct the pressure value to be supplied to the compressor on the basis of the resulting data in such a way that the pressure setpoint of the compressor is reached.

8. The control system of claim 1, wherein the control system has a de-rating limit and a loading limit, and the de-rating limit and the loading limit are adapted to be set based on a range of pressure and pressure fluctuations produced by a single variable displacement compressor.

9. The control system of claim 1, wherein the control system has different deloading limits for a deloading-loading compressor and a variable displacement compressor, the deloading-loading compressor being a compressor that operates using a loading-deloading control scheme.

10. The control system of claim 9, wherein the deloading limit of a variable displacement compressor is adapted to be higher than the deloading limit of a deloading-loading compressor.

11. The control system of claim 1, wherein the control system is adapted to:

the unused capacity of the variable displacement compressor is calculated,

the delivery quantity at the currently considered moment of the next compressor to be de-loaded according to the sequence is further calculated,

inferring from the unused capacity the delivery capacity of the next compressor to be de-loaded,

a safety margin given from a user interface or automatically calculated is inferred from the unused capacity,

and de-rating the compressor if the calculated result is positive.

12. The control system of claim 1, wherein the compression system includes a sensor at a consumption site,

the control system also includes a setting for the desired minimum pressure for a particular point for which it is desired to monitor the pressure and a setting for how much the network pressure can be reduced or increased depending on the pressure at the particular point,

wherein the control system is adapted to control the compressor and to adjust the level of the network pressure in accordance with the given setting.

13. A method for controlling a compression system, the compression system comprising: a compressor (C1-C7) and its controller (A1-A7), said compressor (C1-C7) and its controller (A1-A7) being used for compressing a fluid medium; a secondary treatment device for treating the fluid medium delivered from the compressor; -a pipe system (17-19, 23), which pipe system (17-19, 23) is intended to conduct the fluid medium to a consumption site (16, 22); and a control system comprising a control unit (3), the control unit (3) comprising: a data processing system (34), the data processing system (34) for controlling the compression system; a user interface (35), the user interface (35) including a display associated therewith; and transmission means for transmitting control data between the control unit, the controller and the pressure sensor,

it is characterized in that the preparation method is characterized in that,

wherein the network delivery request or the network pressure setting or the compressor specific pressure setting is translated into a compressor specific control request via direct control data, pressure setting or pressure data item of the compressor.

14. The method of claim 13, wherein the compressor has a limit on the adjustment range of the delivery amount, the limit determined from the user interface.

15. Method according to claim 13 or 14, characterized in that the network delivery request or the network pressure setting is converted into a delivery request to a variable displacement compressor based on an allowable adjustment range of the delivery amount of the compressor and/or based on an efficiency curve of the compressor.

16. The method of claim 15, characterized in that the effect of the efficiency curve is taken into account if one or more of the compressors is delivered with a substantially larger delivery with a better efficiency ratio and there is also a better efficiency ratio of the compressors delivered with a substantially smaller delivery.

17. Method according to claim 13, characterized in that the delivery request is further converted into a control request for the compressor, using a direct reference derived from the rotational speed, a reference derived from a percentage of the delivered amount of the compressor or a reference derived from the attitude of the suction vanes.

18. The method according to claim 17, characterized in that an adjustment value for what delivery quantity the compressor is expected to deliver is calculated for a compressor, or a sensor is given of a pressure level and the compressor is expected to run,

further calculating the rotational speed or the attitude of the suction vanes, pressure setting or simulated network pressure data item for sending to the compressor as a control request.

19. Method according to claim 13, characterized in that the compressor power is measured or the pressure value measured by a sensor is read, and the pressure value to be supplied to the compressor is corrected on the basis of the resulting data in such a way that the pressure setpoint of the compressor is reached.

20. The method of claim 13, wherein the control system has a de-rating limit and a loading limit, and the de-rating limit and the loading limit are set based on a range of pressure and pressure fluctuations produced by a single variable displacement compressor.

21. The method of claim 13, wherein the control system has different deloading limits for a deloading-loading compressor and a variable displacement compressor, the deloading-loading compressor being a compressor that operates using a load-deloading control scheme.

22. The method of claim 21, wherein the deloading limit of a variable displacement compressor is higher than the deloading limit of a deloading-loading compressor.

23. Method according to claim 13, characterized in that in the method:

calculating an unused capacity of the variable displacement compressor;

further calculating the delivery quantity at the currently considered moment of the next compressor to be deloaded according to the sequence;

inferring from the unused capacity the delivery capacity of the next compressor to be de-loaded;

inferring a safety margin from the unused capacity given from a user interface or automatically calculated;

and de-rating the compressor if the calculated result is positive.

24. The method of claim 13, wherein the compression system includes a sensor at a consumption site,

wherein the control system controls the compressor and adjusts the level of the network pressure according to the given setting.