Method for controlling at least one photovoltaic conversion device electrically connected to an electrolyser

Abstract

The present invention relates to a method for controlling a hydrogen production installation (100), the method comprising the following successive steps: - determining a first magnitude of a nominal operating electric current (In) of at least one electrolyser (50); - measuring a second magnitude of an electric current (Imes flowing through a connection (22) between the electrolyser (50) or at least one of the electrolysers (50) and at least one photovoltaic conversion device (10); and - orienting the device (10) or at least one of the devices (10) such that the second magnitude (Imes) is less than or equal to the first magnitude (In).

Description

[0001] DESCRIPTION

[0002] TITLE: Method for controlling at least one photovoltaic conversion device electrically connected to an electrolyser

[0003] FIELD OF THE INVENTION

[0004] The invention relates to the production of hydrogen using electrolysers supplied with electric current by adjustable photovoltaic panels.

[0005] STATE OF THE ART

[0006] Hydrogen can be produced by electrolysis of water using electrolysers powered by photovoltaic panels. This is one of the means of producing so-called "green" hydrogen, given the use of a renewable energy source to supply the electricity.

[0007] Since the electrolyser is powered by direct current and the panels convert photovoltaic power into direct current electrical power, the two systems can be either directly coupled or connected via a direct current / direct current converter (known by the acronym "DC / DC converter").

[0008] However, in this configuration, all the power from the panels is either directed to the electrolyser or directed to the DC / DC converter upstream of the electrolyser, with the exception of Joule losses dissipated in the cables. Since the latter has a high operating threshold, it is shut down for safety reasons as soon as the power supplied to the electrolyser directly coupled to the panels, or connected via the DC / DC converter, exceeds this threshold value, which causes the loss of possible hydrogen production during this shutdown period.

[0009] One solution is to size the photovoltaic panels so that they provide maximum power as close as possible to a nominal operating point of the electrolyser.

[0010] Another solution is to use the converter's programming to limit the maximum power downstream of the converter, as close as possible to a nominal operating point of the electrolyser. However, in this configuration, the electrolyser's charge rate, i.e. the ratio of its nominal operating time over a year, is low. In this case, it is generally between 15% and 25%.

[0011] As the electrolyser is an expensive piece of equipment, this charging rate therefore has an influence on the price of green hydrogen.

[0012] One aim of the invention is therefore to reduce the cost price of hydrogen in this type of installation.

[0013] STATEMENT OF THE INVENTION

[0014] For this purpose, a method for controlling a hydrogen production installation is proposed, the method comprising the following successive steps:

[0015] - determination of a first magnitude of a nominal operating electric current of at least one electrolyser;

[0016] - measurement of a second magnitude of an electric current passing through a connection between the electrolyser or at least one of the electrolysers and at least one photovoltaic conversion device; and

[0017] - orientation of the device or at least one of the devices so that the second quantity is less than or equal to the first quantity.

[0018] Thus, the orientation of the panel allows, if necessary, to reduce the power of the sunlight it receives so that it delivers an electric current whose magnitude does not exceed the capacities of the electrolyser and possibly its associated converter. This orientation is therefore adapted according to the sunlight to provide the electrolyser as often as possible with power adapted to its capacities. This increases the charging rate of the electrolyser and reduces the price of green hydrogen. The process makes it possible to increase the charging rate above 10% compared to a conventional solution. It also makes it possible not to shut down the electrolyser as a safety measure. The process also makes it possible to reduce the dimensions and the cost of the electrolysers.More specifically, the method makes it possible to exploit photovoltaic fields that are or will be equipped with trackers by reprogramming their control units. Indeed, in addition to programming the trackers to rotate the panels in order to follow the astronomical path of the sun from East to West and to convert maximum photovoltaic power, the panels are oriented in order to ensure that the second magnitude is always less than or equal to the first magnitude. The device can be oriented to place it in at least one intermediate position between two end-of-travel positions of the device.

[0019] It is also possible to orient the device by moving it in discontinuous steps.

[0020] The pitch can be expected to have a value between 1.8° and 2.2°.

[0021] Thus, defining the step value allows the second quantity to be kept as close as possible to the first quantity.

[0022] A preliminary step of positioning the device or at least one of the devices may be provided according to at least one orientation instruction from a control loop, the orientation instruction corresponding to a position in which the device or at least one of the devices converts a predetermined photovoltaic power.

[0023] This ensures that the second magnitude is at its maximum during the day.

[0024] It may be provided that, in the presence of several devices, at least one of the devices is disconnected from the electrolyser or from at least one of the electrolysers so that the second quantity is less than or equal to the first quantity.

[0025] It may also be provided that, in the presence of several devices distributed over several branches, each branch comprising several devices and being electrically connected to the electrolyser or to at least one of the electrolysers, at least one of the branches is disconnected from the electrolyser or to at least one of the electrolysers so that the second quantity is less than or equal to the first quantity.

[0026] This is another way to adapt the power supplied by the panel(s) to the capacity of the electrolyser by disconnecting the device(s) or the branch(es). Thus, the process makes it possible to increase the charging rate above 15% compared to a conventional solution.

[0027] It is also possible to disconnect the device(s) or branch(es) corresponding to a fraction of between 7% and 15% of a power production capacity supplied by all the devices connected to the electrolyser.

[0028] Thus, the fraction of this power production capacity can be calculated based on the number of devices or the number of branches. In addition, defining such a fraction makes it possible to keep the second magnitude as close as possible to the first magnitude. It is also possible to connect the disconnected device or each disconnected branch after a period of between 5 minutes and 20 minutes from the disconnection.

[0029] Thus, defining such a duration also helps to keep the second magnitude as close as possible to the first magnitude.

[0030] The invention also provides a control unit comprising a program comprising code instructions capable of controlling the execution of a method according to the invention when it is executed on a computer.

[0031] The invention also provides a hydrogen production installation comprising:

[0032] - at least one photovoltaic conversion device; and

[0033] - at least one electrolyser electrically connected to the device; the installation (100) being configured to implement the method according to the invention.

[0034] Thus, the cost of producing green hydrogen decreases with such an installation. Indeed, the installation makes it possible to control electrolysers with a power significantly lower than the power of the photovoltaic device.

[0035] It can be expected that the device includes at least:

[0036] - a supporting structure; and

[0037] - a photovoltaic panel mounted mobile relative to the supporting structure.

[0038] It can be provided that the hydrogen production installation comprises several devices and at least one switch adapted to connect or disconnect at least one of the devices with respect to the electrolyser, the installation being configured to control the opening and closing of the or each switch.

[0039] Thus, the cost of producing green hydrogen decreases further with such an installation.

[0040] It can be provided that the hydrogen production installation comprises a direct current / direct current converter electrically connected to the electrolyser and to the or each photovoltaic conversion device.

[0041] The direct current / direct current converter modulates a first current / voltage pair from the photovoltaic panel into a second current / voltage pair intended for the electrolyser to reach the maximum power point that can be supplied by the photovoltaic panel for different operating conditions.

[0042] This converter allows, over a first operating range of the photovoltaic panel, to deliver an electric current whose magnitude does not exceed the capacities of the electrolyser.

[0043] DESCRIPTION OF FIGURES

[0044] We will now describe an embodiment of the invention and variants by way of non-limiting examples with reference to the appended drawings in which:

[0045] Figure 1 illustrates a hydrogen production installation according to one embodiment of the invention;

[0046] Figure 2 and Figure 3 illustrate a hydrogen production installation according to other embodiments of the invention;

[0047] Figure 4 illustrates the evolution of the electrical power output from an adjustable photovoltaic conversion device and a stationary photovoltaic conversion device over one day;

[0048] Figure 5 illustrates the evolution of the power converted by adjustable photovoltaic conversion devices and the nominal power of an electrolyser according to an initial dimensioning over one day;

[0049] Figure 6 illustrates the evolution of the power converted by the adjustable photovoltaic conversion devices and the nominal power of the electrolyser connected to the device according to another dimensioning over one day;

[0050] Figure 7 is a flowchart illustrating a mode of implementation of the method according to the invention;

[0051] Figures 8 to 11 illustrate the operational principle of the flowchart in Figure 6; and

[0052] Figure 12 illustrates the evolution of the output power of the steerable photovoltaic conversion devices according to the invention, the evolution of the output power of the photovoltaic conversion devices in a conventional hydrogen production installation, and the nominal power of the electrolyser connected to the devices over two days. DETAILED DESCRIPTION OF THE INVENTION

[0053] Installation Description

[0054] Figure 1 illustrates a hydrogen production installation 100 according to one embodiment of the invention.

[0055] It includes:

[0056] - photovoltaic conversion devices 10 distributed over several branches 20, each branch comprising several devices 10; and

[0057] - an electrolyser 50 electrically connected to the branches 20.

[0058] According to another embodiment, the hydrogen production installation 100 comprises a group of electrolysers 50 electrically connected to the branches 20 or several groups of electrolysers 50 electrically connected to the branches 20.

[0059] The hydrogen production facility 100 may comprise a direct current / direct current converter 21 (also known by the acronym DC / DC converter) electrically connected to the electrolyzer 50 and to the branches 20. In this case, the direct current / direct current converter 21 may be electrically connected to a device 10, to several devices 10, or to each device 10. The converter may be electrically connected to a group of branches 20 or to several groups of branches 20. The direct current converter 21 may be a chopper. An example of a hydrogen production facility 100 comprising a direct current / direct current converter 21 is illustrated in FIG. 2.

[0060] Each device 10 comprises at least:

[0061] - a supporting structure 12; and

[0062] - a photovoltaic panel 11 mounted mobile relative to the supporting structure 12.

[0063] The supporting structure 12 is defined here as a set of integral elements configured to support a load. For example, the supporting structure 12 may be a mast or a triangulated structure supporting the weight of the photovoltaic panel 11 and the mechanical elements constituting the mobile part of the photovoltaic panel 11.

[0064] Such a device 10 is called a solar tracker. Its function is to better track the sun in order to optimize electricity production. As illustrated in Figure 4, the photovoltaic energy converted over a day is higher compared to a fixed photovoltaic panel 11 relative to the supporting structure 12. Indeed, the area under the curve with tracker 60 is greater than that under the curve without tracker 70. However, the applicant has noticed that this conventional use of the trackers 10, i.e. maximizing the photovoltaic energy converted over a day (see Figure 4), is not suitable for the production of hydrogen. Indeed, in such a case illustrated in Figure 5, the electrolyser 50 only operates for a very short time at full load so that its charge rate is low.

[0065] In another case illustrated in Figure 6, the capacity of the electrolyser 50 is better exploited with a higher charge rate but this requires clipping the converted photovoltaic power so that the electrolyser 50 does not go into a safety mode.

[0066] According to the invention, the clipping is achieved by changing the orientation of the trackers 10. Indeed, the photovoltaic power converted by the trackers 10 is maximum when the panels 11 are facing the sun and it decreases when they are inclined.

[0067] In addition to the orientation of the trackers 10, clipping is also achieved by disconnecting several branches 20. Indeed, in direct current, the input power of the electrolyser 50 is proportional to the number of disconnected branches 20. A similar reasoning can be made with the current.

[0068] For example, for a hydrogen production facility with ten branches, reducing power by 10% corresponds to disconnecting one branch.

[0069] According to another example, for a hydrogen production installation 100 illustrated in figure 3, reducing the power transmitted to the electrolyser by 50% corresponds to disconnecting two branches 20.

[0070] We thus observe in Figure 1:

[0071] - several branches 20 in parallel, each of which comprises trackers 10 connected in series;

[0072] - an electrolyser 50 electrically connected to all of the branches 20;

[0073] - a control unit 40 placed between the branches 20 in parallel on the one hand and the electrolyser 50 on the other hand; and

[0074] - switches 30 positioned so as to disconnect a group of branches relative to the control unit 40.

[0075] For example, such a hydrogen production facility 100 may comprise:

[0076] - a 5 MW 50 electrolyser;

[0077] - six hundred to one thousand branches 20 connected to the electrolyser 50; and

[0078] - ten to twenty trackers 10 connected in series per branch 20. The switches 30 can be located on a group of branches 20 as illustrated in figure 1 or, according to another embodiment, they can be located on each of the branches 20 as illustrated in figure 3.

[0079] According to the configuration illustrated in Figure 1, the number of branches 20 that can be opened stringSDj respects the following inequality: with X corresponding to a fraction of a power production capacity provided by all the trackers 10 connected to the electrolyser 50, and string; corresponding to the branches 20 remaining connected.

[0080] The control unit 40 is configured to:

[0081] - receive an instruction C ei of a nominal operating electric current l n of the electrolyser 50;

[0082] - receive orientation instructions C e 2i, C e 2 P from each control loop of the trackers 10 corresponding to the positions in which they convert maximum photovoltaic power;

[0083] - measure an electric current l me s crossing a connection between the electrolyser 50 and the trackers 10;

[0084] - control the orientation of each tracker 10 by angle instructions C s n, Csi q ; And

[0085] - control the opening or closing of switches 30 by control instructions Cs21, Cs22.

[0086] In order to control the orientation and disconnection of the trackers 10, the control unit 40 comprises code instructions for the execution of a method for controlling the hydrogen production installation 100, one embodiment of the invention of which is presented below.

[0087] Method for controlling an E0 hydrogen production installation according to an embodiment of the invention

[0088] For each moment of the day, there is an orientation for each tracker 10 in which the total output power of the branches 20 remains less than or equal to the nominal power of the electrolyser 50. Thus, the method for controlling the hydrogen production installation 100 makes it possible to clip the photovoltaic power converted by the trackers 10. This method is illustrated by the flowchart in Figure 7, each of the steps of which is detailed below.

[0089] During a step E1, a nominal operating current l is determined n of the electrolyser 50.

[0090] This step can for example be carried out when dimensioning the electrolyser 50 before installing it in the hydrogen production installation 100.

[0091] During a step E2, the installation 100 is in operation. The sun irradiates the panels 11 which supply electric current to the electrolyser 50. The electrolyser 50 produces hydrogen continuously.

[0092] During a step E3, the control unit 40 positions the trackers 10 according to the orientation instructions C e 2i, C e 2 P from each control loop of the trackers 10 and which correspond to the positions in which they convert maximum photovoltaic power.

[0093] During a step E4, the unit 40 measures the current l mes crossing the connection between the electrolyser 50 and the trackers 10 then compares it to the nominal value l n .

[0094] If the measured current l me s is greater than the value of the nominal current l n of the electrolyser 50, then the unit 40 executes a step E5 in which it controls an orientation of the trackers 10 by angle instructions C s n, C siq so that the measured current l me s is less than or equal to the nominal current l n The control unit 40 orients the trackers 10 by moving them between two end-of-travel positions of each tracker 10, for example by moving them in discontinuous steps. Each step in this case has a value between 1.8° and 2.2°.

[0095] For example, in Figure 8, at 11 a.m., the trackers 10 do not provide a current greater than l me s at nominal current l nof the electrolyser 50. The trackers 10 are therefore in a position in which they convert maximum photovoltaic power.

[0096] In Figure 9, at 1 p.m., the trackers 10 provide a current l me s greater than the nominal current l n of the electrolyser 50. The trackers 10, each being in a position in which they convert maximum photovoltaic power, are therefore controlled by the unit 40 to change their orientation to provide less current as illustrated in figure 10. If the measured current l me s is always greater than the value of the nominal current l n of the electrolyser 50, then a step E6 is executed in which the control unit 40 disconnects several trackers 10 by control instructions C S 2i, C S 22 so that the measured current l me s is less than or equal to the nominal current l nIn this case, the number of disconnected trackers 10 corresponds to a fraction of between 7% and 15% of a power production capacity provided by all of the trackers 10 connected to the electrolyser 50.

[0097] Alternatively, according to a configuration like that illustrated in figure 1 or 3 in which the trackers 10 are distributed over several branches 20, each branch 20 comprising several devices 10 and being electrically connected to the electrolyser 50, the control unit 40 disconnects one or more branches 20 so that the measured current es is less than or equal to the nominal current l n In this case, the number of disconnected branches 20 also corresponds to a fraction of between 7% and 15% of a power production capacity provided by all of the trackers 10 connected to the electrolyser 50.

[0098] In the case where the measured current l mes remains greater than the value of the nominal current l n , the control unit 40 shuts down the electrolyser 50 as a safety measure during a step E7. Otherwise, the control unit 40 executes a step E8 in which it waits for a set duration and then reconnects the disconnected trackers 10. In this case, the unit 40 connects the disconnected trackers 10 after a duration of between 5 minutes and 20 minutes from the disconnection.

[0099] Alternatively, the control unit 40 connects the disconnected branches 20 after a period of between 5 minutes and 20 minutes from the disconnection.

[0100] Steps E2 to E6 and step E8 are repeated cyclically.

[0101] For example, in figure 11, at 3 p.m., the sun 90 is again facing the panels 11 of the trackers 10 and according to the value of the measured current l mes in step E4, steps E5 to E6 and step E8 can be repeated or the production of hydrogen continues with the same orientation of the panels 11 as at 1 p.m. by repeating steps E2 and E3.

[0102] The results of the implementation of the method are illustrated in figure 12. The photovoltaic power 61 converted by the panels 11, being a magnitude of the current passing through the connection between the electrolyser 50 and the trackers 10, is each day limited to a threshold value 53 corresponding to the nominal power of the electrolyser 50 to obtain a clipped photovoltaic power 62.

[0103] Of course, numerous modifications may be made to the invention without departing from its scope. The characteristics of the disconnection of the panels or branches 20 of panels 11 relative to the electrolyser 50 may be implemented independently of the orientation ability of the panels 11.

Claims

CLAIMS 1. Method for controlling a hydrogen production installation (100), the method comprising the following successive steps: - determination of a first magnitude of a nominal operating electric current (l n ) at least one electrolyzer (50); - measurement of a second magnitude of an electric current (l me s) passing through a connection (22) between the electrolyser (50) or at least one of the electrolysers (50) and at least one photovoltaic conversion device (10); and - orientation of the device (10) or at least one of the devices (10) so that the second quantity (l me s) is less than or equal to the first quantity (l n ).

2. Method according to the preceding claim in which the device (10) is oriented to place it in at least one intermediate position between two end-of-travel positions of the device (10).

3. Method according to one of claims 1 or 2 in which the device (10) is oriented by moving it in discontinuous steps.

4. Method according to the preceding claim in which the pitch has a value between 1.8° and 2.2°.

5. Method according to one of claims 1 to 4 wherein, in the presence of several devices (10), at least one of the devices (10) is disconnected from the electrolyser (50) or from at least one of the electrolysers (50) so that the second quantity (l me s) is less than or equal to the first quantity (l n ).

6. Method according to one of the preceding claims in which, in the presence of several devices (10) distributed over several branches (20), each branch (20) comprising several devices (10) and being electrically connected to the electrolyser (50) or to at least one of the electrolysers (50), at least one of the branches (20) is disconnected from the electrolyser (50) or to at least one of the electrolysers (50) so that the second quantity (l me s) is less than or equal to the first quantity (l n ).

7. Method according to one of claims 5 or 6 in which the device(s) (10) or the branch(es) (20) corresponding to a fraction of between 7% and 15% of a power production capacity supplied by all of the devices (10) connected to the electrolyser (50) are disconnected.

8. Method according to one of claims 5 to 7 in which the or each disconnected device (10) or the or each disconnected branch (20) is connected after a period of between 5 minutes and 20 minutes from the disconnection.

9. Control unit (40) comprising a program comprising code instructions capable of controlling the execution of a method according to one of the preceding claims when executed on a computer.

10. Hydrogen production facility comprising: - at least one photovoltaic conversion device (10); and - at least one electrolyser (50) electrically connected to the device (10); the installation (100) being configured to implement the method of one of claims 1 to 8.

11. Hydrogen production installation according to the preceding claim in which the device (10) comprises at least: - a supporting structure (12); and - a photovoltaic panel (11) mounted to move relative to the supporting structure (12).

12. Hydrogen production installation (100) according to one of claims 10 or 11 comprising several devices (10) and at least one switch (30) adapted to connect or disconnect at least one of the devices (10) relative to the electrolyser (50), the installation being configured to control the opening and closing of the or each switch (30).

13. Hydrogen production installation (100) according to one of claims 10 to 12 comprising a direct current / direct current converter (21) electrically connected to the electrolyser (50) and to the or each photovoltaic conversion device (10).

Images