METHOD AND MODULE CONTROLLER FOR CONTROLLING A POWER PRODUCING SYSTEM

Abstract

A module controller and a method for controlling operation of power producing modules in a power producing system are provided. The module controller comprises a processor and a memory, configured to store instructions, which when executed by the processor performs the method by causing the module controller to identify each power producing module connected to the module controller, retrieve a control logic for and associated with each of the identified power producing modules, determining the order in which the power producing modules are to be controlled by the module controller, allocate processor time to each power producing module and control the operation of each power producing module by executing, in the processor, the associated control logic.

Claims

1. A method of controlling a power producing system comprising at least two power producing modules and a module controller for controlling operation of the power producing modules, wherein the module controller comprises a processor, the method comprising: identifying each power producing module connected to the module controller; retrieving a control logic for and associated with each of the identified power producing modules; scheduling a control sequence which determines an order in which the power producing modules are to be controlled by the module controller; allocating processor time to each power producing module in accordance with the scheduled control sequence; and controlling the operation of each power producing module by executing, in the processor, the associated control logic.

2. The method according to claim 1, wherein the identifying of each power producing module comprises reading a configuration file stored in a memory of each respective power producing module.

3. The method according to claim 1, wherein the control sequence is scheduled to restart at regular periods.

4. The method according to claim 3, wherein the regular periods restart at an interval between 25 and 100 ms.

5. The method according to claim 1, wherein the allocation of the processor time is determined based on a complexity of the control logic.

6. The method according to claim 1, wherein the module controller further comprises a safety processor executing a security logic, and wherein the method further comprises: reading, from a memory, a security status of each power producing module; determining that the security status is critical in one power producing module of the power producing modules; classifying the critical security status as either an internal status or an external status; and in response to the classifying of the critical security status, sending, from the safety processor, instructions to the processor to (i) terminate operation of all power producing modules if, when the critical security status is classified as the external status, and (ii) terminate operation of the one power producing module that generated the critical security status, when the critical security status is classified as the internal status.

7. The method according to claim 6, further comprising, when the critical security status has been classified as the internal status: re-scheduling the control sequence; and re-allocating processor time based on the terminated operation of the one power producing module that generated the critical security status classified as the internal status.

8. A module controller for controlling operation of power producing modules in a power producing system, the module controller comprising a processor and a memory configured to store instructions, which when executed by the processor, cause the module controller to perform operations comprising: identifying each power producing module connected to the module controller; retrieving a control logic for and associated with each of the identified power producing modules; scheduling a control sequence, which determines an order in which the power producing modules are to be controlled by the module controller; allocating processor time to each power producing module in accordance with the scheduled control sequence; and controlling the operation of each power producing module by executing, in the processor, the associated control logic.

9. The module controller according to claim 8, wherein each power producing module is identified by reading a configuration file stored in a memory of the respective power producing module.

10. The module controller according to claim 8, wherein the operations include scheduling the control sequence to restart at regular periods.

11. The module controller according to claim 10, wherein the regular periods restart at an interval between 25 and 100 ms.

12. The module controller according to claim 8, wherein the allocation of the processor time is determined based on a complexity of the control logic.

13. The module controller according to claim 8, wherein the module controller further comprises a safety processor, which, when executing a security logic, causes the module controller to perform operations comprising: reading a security status from a memory of each power producing module; determining that the security status is critical in one power producing module of the power producing modules; classifying the critical security status as either an internal status or an external status; and in response to the classifying of the critical security status, sending, from the safety processor, instructions to the processor to (i) terminate operation of all power producing modules, when the critical security status is classified as the external status, and (ii) terminate operation of the one power producing module that generated the critical security status, when the critical security status is classified as the internal status.

14. The module controller according to claim 13, wherein, when the critical security status has been classified as the internal status, the module controller further performs operations including: re-scheduling the control sequence; and re-allocating processor time based on the terminated operation of the one power producing module that generated the critical security status classified as the internal status.

15. (canceled)

16. (canceled)

17. A non-transitory computer-readable recording medium having computer instructions recorded thereon for controlling a power producing system comprising at least two power producing modules and a module controller including a processor and for controlling operation of the power producing modules, the computer instructions, when executed on one or more processors, causing the one or more processors to implement operations comprising: identifying each power producing module connected to the module controller; retrieving a control logic for and associated with each of the identified power producing modules; scheduling a control sequence which determines an order in which the power producing modules are to be controlled by the module controller; allocating processor time to each power producing module in accordance with the scheduled control sequence; and controlling the operation of each power producing module by executing, in the processor, the associated control logic.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0026] FIG. 1a shows a schematic view of a power producing system, comprising power producing modules and a module controller.

[0027] FIG. 1b shows a schematic view of another power producing system, with power producing modules connected both in series and parallel and a module controller.

[0028] FIG. 2 shows a schematic view of a module controller for controlling operation of power producing modules.

[0029] FIG. 3 shows a schematic view of a power producing module.

[0030] FIG. 4 is a flow chart showing the method for controlling a power producing system.

[0031] FIG. 5 illustrates an exemplary embodiment of a power producing module.

[0032] FIG. 6 shows another exemplary embodiment of a power producing module.

DESCRIPTION

[0033] The present invention generally relates to controlling a power producing system comprising two or more power producing modules. In context of the present application a power producing module may be single unit utilizing a power generator such as a steam turbine coupled to a generator, as described further in FIG. 6, or a heat power unit, which utilizes a power generator such as a gas turbine coupled to a generator, as described further in FIG. 5 or a heat power unit group comprising several heat power units. In other embodiments, the power producing modules may also utilize different types of power generators such as for example wind or water turbines or combustion engines of any kind. The main point is that there is a modularity, i.e. that there is a power producing system that comprises two or more power producing modules, the operation of which needs to be controlled.

[0034] As mentioned above creating modularity, as such, is not a major problem but it increases the costs since up to now each power producing module requires its own module controller. This is especially true when it comes to harvesting power from low temperature heat. When harvesting power from low temperature heat it is very important to control and tune the process very efficient in order to get any return on investment. Thus, each power producing module needs to be controlled in a dedicated way to optimize the energy extraction of each power producing module, i.e. there is a dedicated control logic for each power producing module.

[0035] As will be described below the inventor found that it is possible to use a centralized module controller and still use dedicated control logic for each power producing module. As an option such a centralized module may comprise security logic, which further improves the modularity and enhances plug and play functionality of the power producing system. Thus, with the present invention it is possible to create a simple and scalable design of the power producing system, which is easy to install, and which comes with low maintenance costs. The power producing modules may be configured either serially or parallelly to make optimal use of a heat source. Due to the modular design and the way the operation of the power producing modules is controlled, individual power producing modules may be taken offline for service without having to shut down the entire power producing system or site, maximizing site availability.

[0036] FIG. 1a shows a power producing system 2 comprising six power producing modules 4, a controller module 6, control logic 8 and security logic 10. In the power producing system 2 of FIG. 1a the power producing modules 4 are connected in series but may depending on the configuration of the power producing system 2 also be connected in parallel, as described above. The number of power producing modules 4 is at least two but may be extended to ten or more power producing modules 4 depending on the capacity of the module controller 6, which will be described below. The module controller 6 will be closer described in conjunction with FIG. 2 and the power producing module 4 will be closer described in conjunction with FIG. 3.

[0037] FIG. 1b shows a schematic view of another power producing system harvesting heat from a heat source having a certain available hot fluid flow and temperature, with power producing modules 4 connected both in series and parallel and a module controller 6. This really shows the modularity and flexibility of the system. The system can be configured both in parallel and series. This flexibility makes it possible to optimize the utilization of the available hot source flow and temperature. For example, the power producing system 2 may be a distributed geothermal heat power system utilizing low-temperature heat source such as hot fluid, brine or water, from a geothermal well. The inflow of fluid Inflow 1 from the hot source to the first power producing modules 4a1, 4b1, 4c1, 4d1, in a series may have a first temperature Temp 1 of 120° C. The inflow rate of hot fluid is in this case preferably about 80-120 liters per second divided into four parallel flows, Inflow 1-4. Said Inflow 1-4 is therefore for example approximately 20-30 liters per second or more. The outflow temperature Temp 2 from the first series of power producing modules 4a1, 4b1, 4c1, 4d1 after that the heat energy is harvested is approximately 110° C. Said hot source fluid with temperature Temp 2 is used as input to the second power producing modules 4a2, 4b2, 4c2, 4d2, in the series. Each energy harvesting step over each module reduces the temperature of the hot source fluid with approximately 10 degrees. Thus, Temp 3 may be 100° C., Temp 4 may be 90° C. and Temp 5 may be 80° C. The practical aspect of this modularity is that one and the same type of power producing module 4 can be used to expand the power producing system 2 flawlessly and hassle-free. The power producing module 4 is flexible and may be used for different inflows and temperatures without any customization, which makes it perfect for a quick and secure deployment.

[0038] For example, if a heat source or well today provide 80 liters per second of 120° C. hot water, this may change over time due to for example geothermal activity or industrial processes. Thus, if there is more heat potential than calculated you can simply install more power producing modules 4 in the future if you expand your power producing system. It is also possible to remove and move power producing modules if the well or heat source deliver less heat or flow than calculated.

[0039] FIG. 2 shows a schematic view of the module controller 6 for controlling the operation of the power producing modules 4. The module controller 6 is configured to and is operable to perform the method to be described in conjunction with FIG. 4. The module controller 6 comprises a processor 12 and a memory 14. In context of the present application the term processor 12 should be interpreted broadly as processing circuitry, which may comprise one or more programmable processors, application-specific integrated circuits, field programmable gate arrays or combinations of these (not shown) adapted to execute instructions. The memory 14 contains instructions, i.e. a computer program 16, executable by said processing circuitry, whereby the module controller 6 is operative to control the power producing modules 4 connected thereto. The control logic 8 for each power producing module 4 that is connected to the module controller 6 is stored in the memory 14. Each control logic 8 is associated with and dedicated to one power producing module 4. In a preferred embodiment also security logic 10 is stored in the memory 14. When the security logic 10 is executed by a safety processor 22 the security status of each connected power producing module 4 will be checked. As mentioned above the term processor should be interpreted broadly, in context of the present application, as processing circuitry, i.e. also the safety processor 22 may comprise one or more programmable processors, application-specific integrated circuits, field programmable gate arrays or combinations of these adapted to execute instructions.

[0040] The module controller 6 further comprises an interface 19, which may be considered to comprise conventional means for communication with other units and devices, such as the connected power producing modules 4.

[0041] The computer program 16 may comprise computer readable code means, which when run by the processors 12, 22 causes the module controller 6 to perform the steps described in the method below in conjunction with FIG. 4. The computer program 16 may also be carried by a computer program product connectable to the processor 12. The computer program product may be the memory 14. The memory 14 may be realized as for example a RAM (Random-access memory), ROM (Read-Only Memory) or an EEPROM (Electrical Erasable Programmable ROM). Further, the computer program may be carried by a separate computer-readable medium 17, such as a CD, DVD or flash memory, from which the program could be downloaded into the memory 14. Alternatively, the computer program may be stored on a server or any other entity connected or connectable to the module controller 6 via the interface 19. The computer program may then be downloaded from the server into the memory 14.

[0042] Turning now to FIG. 3, the power producing module 4 will be closer described. The power producing module 4 is very schematically shown in FIG. 3 and principally only shows the controlling functions of the power producing module 4. The power producing as such is only shown as a cloud 150 in FIG. 3. Examples of the power producing as such are closer described in conjunction with FIG. 5 and FIG. 6. The controlling functions of the power producing module 4 comprises a controller 100. The controller 100 is configured and operable to communicate with the module controller 6 and control the operation of its power producing module 4 as instructed by the module controller 6. In an exemplary embodiment the controller 100 is a Proportional Integral Derivative, PID, regulator, a Programable Logic Controller, PLC, a personal computer or any other suitable control system. The controller 100 comprises a processor 120 and a memory 140. In context of the present application the term processor 120 should, as mentioned above, be interpreted broadly as processing circuitry and may comprise one or more programmable processors, application-specific integrated circuits, field programmable gate arrays or combinations of these adapted to execute instructions. The memory 140 contains instructions executable by said processing circuitry.

[0043] According to other embodiments, the power producing module 4 may further comprise an interface 190, which may be considered to comprise conventional means for communication with other units or devices, such as the module controller 6. The instructions executable by the processor 120 may be arranged as a computer program 160 stored e.g. in the memory 140. The computer program 160 may comprise computer readable code means, which when run in the processor 120 of the controller 100 causes the controller 100 to control the power producing module 4 according to the instructions received from the module controller 6. The computer program 160 may be carried by a computer program product connectable to the processor 120. The computer program product may be the memory 140. The memory 140 may be realized as for example a RAM (Random-access memory), ROM (Read-Only Memory) or an EEPROM (Electrical Erasable Programmable ROM). Further, the computer program may be carried by a separate computer-readable medium 170, such as a CD, DVD or flash memory, from which the program could be downloaded into the memory 140. Alternatively, the computer program may be stored on a server or any other entity connected or connectable to the power producing module 4 via the interface 190. The computer program may then be downloaded from the server into the memory 140.

[0044] Turning now to FIG. 4 the method performed by the module controller 6 according to the present invention will be closer described by means of a flow chart. The method is applicable when controlling a power producing system 2 comprising two or more power producing modules 4. Compared to the traditional way of controlling power producing modules 4, the full potential of the method is achieved when several power producing modules 4 are connected to the module controller 4. In prior art one dedicated controller is used for each power producing module 4, but with the method according to the present invention it is possible to use only one module controller 6 for controlling the operation of all connected power producing modules 4.

[0045] The method starts at step S102, in which the module controller 6 identifies each power producing module 4 connected to the module controller 6. By identifying each power producing module 4, it is possible for the module controller 6 to control each power producing module 4, individually, depending on type, size, configuration etc. of each individual power producing module 4. In one exemplary embodiment the identification of each power producing module 4 comprises reading a configuration file stored in the memory 140 of the power producing module 4. The identification may also be done by reading a unique identification number or serial number stored in the memory 140 of the power producing module 4.

[0046] In step S104, the module controller 6, retrieves a control logic 8 for and associated with each of the identified power producing modules 4. The retrieving step S104 may be performed in a variety of ways depending on how the power producing system 2 is configured and on the types of power producing modules 4 that are connected thereto. In one exemplary embodiment the control logic 8 is downloaded to the memory 14 of the module controller 6 when the power producing system 2 is set up and during operation the control logic 8 is retrieved directly from the memory 14 of the module controller 6. In another exemplary embodiment, the module controller 6 may retrieve the control logic 8 from a database which stores the control logic 8 for all different types of power producing modules 4. Such a database may be connected directly to the module controller 6 or may be provided in a cloud solution to which the module controller 6 has access.

[0047] In step S106, the module controller 6, schedules a control sequence, i.e. determines the order in which the power producing modules 4 are to be controlled by the module controller 6. The control sequence may be configured in different ways depending on how the system is set up, i.e. depending on if the power producing modules 4 are connected in series, in parallel or any combination thereof. In an exemplary embodiment the control sequence is scheduled to restart at regular periods, balancing the time each power producing module 4 needs to be controlled and the number of power producing modules 4 that are connected to the module controller 6. The regular periods may restart at an interval between 25 and 100 ms, preferably once every 50 ms. In situations where it is difficult to balance the individual processing time needed by each power producing module 4 and the number of power producing modules 4 the module controller 6 may be upgraded with a more powerful processor 12.

[0048] In step S108, the module controller 6, allocates processor time to each power producing module 4 in accordance with the scheduled control sequence. The allocation of processor time is determined based on control logic 8 complexity and may thus differ between the different connected power producing modules 4. In step S110, the module controller 6, controls the operation of each power producing module 4 by executing, in the processor 12, the associated control logic 8.

[0049] In an exemplary embodiment of the power producing system 2, the module controller 6 may further be provided with an optional safety processor 22, which will enhance plug and play functionality. Thus, it will be possible to connect or disconnect power producing modules 4 during operation of the power producing system 2 logic, i.e. without shutting down the power producing system 2. The safety processor 22 is configured to execute the security logic 10 stored in the memory 14 of the module controller 4.

[0050] When the module controller 6 is provided with the safety processor 22, the module controller 6, in step S112, reads the security status of each power producing module 4. The security status is stored in the memory 140 of each power producing module 4, respectively. The module controller 6 checks if the security status is critical in any one of the power producing modules 4. If the security status is critical somewhere in the power producing system 2, the module controller 6 determines, in step S114, that the security status is critical in one of the producing modules 4. In step S116, the module controller 6 classifies the critical security status as either an internal status or an external status. An internal security status is defined as being a security status that only affects the power producing module 4 that generated the security critical status, i.e. an internal error. An external security status is defined as being a security status that affects the whole power producing system 2 and not only the power producing module 4 that generated the security critical status.

[0051] In step S118, the module controller 6 sends, in response to that it has been determined that the security status is critical, instructions from the safety processor 22 to the processor 12 to terminate operation of all power producing modules 4 if the critical security status is classified as the external status or to terminate operation in the power producing module 4 that generated the critical security status if the critical security status is classified as the internal status.

[0052] If the critical security status has been classified as the internal status, the method may further comprise re-scheduling of the control sequence in step S120 and re-allocating the processor time, in step S122, based on the terminated operation in the power producing module 4 that generated the critical security status classified as the internal status.

[0053] Thus, by using a safety processor 22 and determining the type of critical security status it is possible to connect and disconnect individual power producing modules 4 from the power producing system 2 without the need to interrupt the operation of the entire power producing system 2. This gives a very flexible power producing system 2, which is easy to maintain and where power producing modules 4 are readily added or removed. This is accomplished by separating the operational system (processor 12) from the security system (safety processor 22).

[0054] Turning now to FIG. 5 an exemplary embodiment of a power producing module 4 will be described. This is just an example and it should be understood that the method according to the present invention may be used with any type of power producing module 4. Another exemplary embodiment of a power producing module 4 will be described in conjunction with FIG. 6.

[0055] FIG. 5 shows a first heat exchanger 1 as part of a power producing module 4. The power producing module 4 is a closed loop thermodynamic system, preferably an Organic Rankine Cycle, ORC, system. The ORC system comprises a circulating working medium, i.e. the first medium, circulating through a gas turbine 20 coupled to a generator 25 which is configured to generate electric power while expanding the gas which is produced in the first heat exchanger 1 by boiling and overheating the working medium into a dry gas. The boiling and overheating are accomplished by guiding the hot fluid for the heat source, i.e. heat transferring second medium, through the first heat exchanger 1. The gas which has passed through the turbine 20 is condensed in a condenser 30. The condenser 30 comprises a second heat exchanger 30a arranged to cool a stream of working medium with a cooling medium originating for a cold source and a separate condenser tank 30b in which the gaseous working medium condense by cooling the gas with the cold stream of working medium. The second heat exchanger 30a has an inlet 36 and an outlet 37 for the cooling medium as well as an inlet 33 and an outlet 32 for the working medium. In another exemplary, not shown, embodiment the condenser 30 may be a single heat exchanger unit in which the gaseous working medium is directly condensed by indirect or direct contact with the cooling medium.

[0056] A regulator 40, 41 conveys the working medium condensed in the condenser 30 to the first heat exchanger 1. The working medium (i.e. the first medium) enters the first heat exchanger 1 via an inlet port 28 of the first medium and exits through an outlet port 3 of the first medium in form of gas. The second medium enters the first heat exchanger 1 via an inlet port 26 of the second medium and then exits via the outlet port 7 of the second medium. A PID regulator 100 is controlling the operation of the regulators 40, 41 based on temperatures measured by sensors 15, 27 measuring the temperature of the second medium flow in and out of the first heat exchanger 1 and also based on the pressure and temperature of the working medium exiting the first heat exchanger 1 measured by the sensor 11.

[0057] Turning now to FIG. 6 another exemplary embodiment of a power producing module 4 will be described. In this embodiment the power producing module 4 comprises a steam turbine 20 through which a medium is circulated. The steam turbine 20 is coupled to a generator 25 which is configured to generate electric power. The flow of medium through the gas turbine is determined by a PID regulator 100 which controls a valve 41. Thus, the power producing module 4 in FIG. 6 is one very simple module. The point is that the method of the present invention may be implemented using different types of power producing modules for building up a power producing system 2. The modularity of the power producing system 2 may have several levels, i.e. the whole power producing system 2 of FIG. 1a or FIG. 1b may also be seen as one power producing module 4 and could be connected to other such “large” power producing modules in order to harvest even more energy from the available energy sources. Thus, the method according the present is very flexible and scalable and may be implemented in wide variety of power producing systems.

[0058] Although the description above contains a plurality of specificities, these should not be construed as limiting the scope of the concept described herein but as merely providing illustrations of some exemplifying embodiments of the described concept. It will be appreciated that the scope of the presently described concept fully encompasses other embodiments which may become obvious to those skilled in the art, and that the scope of the presently described concept is accordingly not to be limited. Reference to an element in the singular is not intended to mean “one and only one” unless explicitly so stated, but rather “one or more.” All structural and functional equivalents to the elements of the above-described embodiments that are known to those of ordinary skill in the art are expressly incorporated herein and are intended to be encompassed hereby. Moreover, it is not necessary for the controller or method to address each and every problem sought to be solved by the presently described concept, for it to be encompassed hereby. In the exemplary figures, a broken line generally signifies that the feature within the broken line is optional.