AU2018200740A1 - Photovoltaic Installation for an Industrial Site with Device for Storing Energy on Fork-Lift Trucks - Google Patents

Abstract

Abstract The invention relates to a photovoltaic installation (1) for an industrial site (8) comprising photovoltaic panels (2), a DC/AC converter (4) of which the primary (4a) is connected to the photovoltaic panels, a bidirectional energy metering device (9) connected, on the one hand, to the secondary (4b) of the DC/AC converter and, on the other hand, to the network of a supplier of electricity (7), at least one bidirectional AC/DC converter (11) of which the primary (11a) is connected to the secondary (4b) of the DC/AC converter, at least one control device (16) configured to control at least one bidirectional AC/DC converter (11) according to the metering data supplied by the bidirectional energy metering device (9) and at least one fork-lift truck comprising a rechargeable battery (19) connected to the secondary (1Ib) of the bidirectional AC/DC converter (11). 4 7, 4 2=Z I-9 7 -- 16 1 13 10a Figure2I L - - - - - - -I

Description

Photovoltaic Installation for an Industrial Site with Device for Storing Energy on Fork-Lift Trucks

Technical field [0001] This invention relates to the field of photovoltaic installations on industrial sites. It relates very particularly to optimising the use of the solar energy produced on the industrial site.

PRIOR ART [0002] Implementing photovoltaic installations on industrial sites is well known. Conventionally, such an installation comprises photovoltaic panels that produce electrical energy under the action of the sun. This electrical energy is transformed via a DC/AC converter in order to be used on the industrial site, with the surplus energy produced being injected into the network of the electricity supplier for a resale price which can be lower than the purchase price of the electricity.

[0003] The production of electrical energy by means of the photovoltaic installation is maximum during the peak hours of solar production. On the contrary, many industrial sites generally consume little energy during these peak hours of solar production, while they sometimes consume more outside of this period since it is necessary to illuminate and heat buildings and offices of the industrial site and to operate the site over much wider time slots, in the morning and in the evening, for example. In other terms, there is a need for an alignment between production and consumption, with this being more or less favourable according to the electric charge curves and the solar production curves.

Summary of the invention [0004] This invention has for objective to use as best as possible the solar energy produced on the industrial site for its own consumption by reducing the quantity of electricity purchased from the electricity supplier and the quantity of electricity injected into the network of said supplier of electricity.

2018200740 31 Jan 2018 [0005] To this effect, the invention relates to a photovoltaic installation of an industrial site allowing for the production of solar energy converted into electricity for use on the industrial site or even a reinjection of this electricity into the supplier's network for a sales price, during an excess production of energy that is not used on said site.

[0006] The photovoltaic installation comprises:

- at least one photovoltaic panel for the production of solar energy in the form of a DC voltage,

- a first DC/AC converter comprising a primary and a secondary, with the primary being connected to the at least one photovoltaic panel, with the converter making it possible to convert the DC voltage at the primary into AC voltage at the secondary,

- a bidirectional energy metering device connected, on the one hand, to the secondary of the DC/AC converter and, on the other hand, to the network of a supplier of electricity, such a metering device that makes it possible to meter the quantity of electricity taken from the network of the supplier of electricity or, on the contrary, the quantity of electricity injected into said network.

[0007] The term primary of the first DC/AC converter means the connection terminals of the direct portion and the term secondary of said converter means the connection terminals of the alternating portion.

[0008] Remarkably, the photovoltaic installation according to the invention comprises:

- at least one second bidirectional AC/DC converter comprising a primary and a secondary, with the primary being connected in parallel on the secondary of the first DC/AC converter;

- at least one control device configured to control the bidirectional AC/DC converter according to the metering data supplied by the bidirectional energy metering device;

- at least one fork-lift truck comprising a rechargeable battery connected to the secondary of the bidirectional AC/DC converter.

[0009] The term primary of the second bidirectional AC/DC converter means the connection terminals of the alternating portion and the term secondary of said converter means the connection terminals of the direct portion.

2018200740 31 Jan 2018 [0010] In terms of the invention, the term second bidirectional AC/DC converter means a bidirectional AC/DC converter, as such, or a bidirectional AC/DC conversion system the provides the same function as that of a bidirectional AC/DC converter. In an embodiment, this bidirectional AC/DC conversion system is comprised of a fork-lift truck charger providing an AC/DC conversion function, of an inverter providing the function of a DC/AC converter and of a switch. The charger and the inverter are mounted in parallel between them and connected in parallel on the secondary of the first DC/AC converter by the intermediary of the switch which makes it possible to switch either to the charger or to the inverter, with said switch being controlled by the control device.

[0011] In terms of the invention, the term fork-lift truck means a fork-lift truck, as such, or any similar handling vehicle working by means of a rechargeable battery.

[0012] The connection of the primary of the second converter can be carried out to the secondary of the first converter, in parallel of the distribution network of the industrial site. The interest in carrying out this connection in parallel is however to be able to connect the primary of the second converter with regards to the secondary of the first converter anywhere on the distribution network of the industrial site, for example according to the usual location of the fork-lift trucks on said industrial site.

[0013] The bidirectional metering device makes it possible to measure when energy is injected into the network of the supplier of electricity, i.e. when the consumption on the industrial site is less than the quantity of solar energy produced. The control device or devices receiving the data from the bidirectional metering device then control the bidirectional AC/DC converter or converters so that they operate in AC/DC mode, the surplus energy produced by the photovoltaic installation, not consumed by the industrial site, is then used to recharge the batteries of the fork-lift trucks rather than injecting this surplus of energy into the network of the supplier of electricity. On the contrary, when the bidirectional metering device measures a quantity of energy taken from the network of the supplier of electricity, i.e. when the consumption on the industrial site is greater than the quantity of solar energy produced, the control device or devices control the bidirectional AC/DC converter or converters so that they operate in DC/AC mode. In this second case, the energy of the battery of the fork-lift truck is transmitted as direct current then converted into alternating current in order to be injected into the network of the industrial site, through a simple socket, rather than

2018200740 31 Jan 2018 taking the power from the network of the supplier. The energy required for the operation of the industrial site is then taken with priority from the solar panels and batteries of the connected fork-lift trucks, before taking electricity from the network of the supplier of electricity. The invention as such makes it possible to minimise the quantity of electricity purchased from the supplier of electricity.

[0014] Furthermore, the invention makes it possible to constantly use the fork-lift trucks present on the site. When it is necessary to use one of the fork-lift trucks for its first use (handling), it is sufficient to disconnect it from the photovoltaic installation. When the handling operation is complete, it is sufficient to reconnect said truck to the distribution network of the industrial site in order to recharge the battery of the truck in the case of excess solar energy produced or in order to use this battery as a source of energy in the case of underproduction of solar energy compared to the power consumed on the industrial site. The constant using and recharging of the fork-lift trucks is beneficial for the batteries that are provided on these trucks due to their less-deep charge cycles, which makes it possible to extend their service life.

[0015] Preferably, the bidirectional energy metering device implemented on the photovoltaic installation object of the invention is entirely independent from the bidirectional energy metering device installed by the supplier of electricity, in order to not touch the installation of said supplier of electricity and to be able to very easily add the various missing modules on a photovoltaic installation that already exists on an industrial site.

[0016] According to a first embodiment of the invention, the photovoltaic installation comprises a single bidirectional AC/DC converter and a single control device. Furthermore, first means of removable connection are arranged between the battery of at least one fork-lift truck and the secondary of the bidirectional AC/DC converter. This implementation makes it possible to be able to use the trucks that are already present on the industrial sites, without requiring any modification.

[0017] According to this first embodiment of the invention, the first means of removable connection are configured to prevent the electric arcs during the connecting or disconnecting of a fork-lift truck with regards to the secondary of the bidirectional AC/DC converter. As such any damage is prevented of the photovoltaic installation due to the frequency of

2018200740 31 Jan 2018 connecting and disconnecting trucks in order to carry out handling operations. Preferably, the first means of removable connection include a male connector and a female connector connected, via cables, one to the truck and the other to the secondary of the bidirectional AC/DC converter, and first resistive means configured to charge or discharge first capacitive means on said bidirectional AC/DC converter.

[0018] It is possible however to consider a second embodiment of the invention, according to which the photovoltaic installation comprises as many bidirectional AC/DC converters and control devices as there are fork-lift trucks, with said elements being on-board said trucks. Furthermore, second means of removable connection are arranged between each fork-lift truck and the secondary of the DC/AC converter. The second means of removable connection are configured to prevent electric arcs during the connecting or disconnecting of a fork-lift truck with regards to the secondary of the DC/AC converter, which prevents damaging the connection despite the usage frequency of the truck for the handling operations. Preferably, these second means of removable connection include a male connector and a female connector connected, via cables, one to the truck and the other to the secondary of the DC/AC converter, and second resistive means configured to charge or discharge second capacitive means on said DC/AC converter.

[0019] According to the invention, the control device is comprised of an automatic device for strategic controlling which recovers the data from the bidirectional metering device and which controls the bidirectional AC/DC converter either in AC/DC mode in order to charge the battery of the fork-lift truck, or in DC/AC mode to restore the electricity on the industrial site.

Brief Description of the Figures [0020] The characteristics and advantages of the invention shall appear when reading the following description along with the figures, among which:

- Figure 1 shows a first embodiment of the photovoltaic installation;

- Figure 2 shows a second embodiment of the photovoltaic installation;

- Figure 3 shows a third embodiment of the photovoltaic installation, according to which the bidirectional AC/DC converter present on the first embodiment of figure 1, is implemented by the intermediary of a fork-lift truck charger and an inverter.

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Detailed Description [0021] In the rest of the description, the same references are used to describe the same characteristics according to the different alternative embodiments of the invention.

[0022] In figure 1, the photovoltaic installation 1 comprises photovoltaic panels 2 which make it possible to generate a DC voltage. These photovoltaic panels 2 are connected by the intermediary of a cable 3 to the primary 4a of a DC/AC converter 4 of the solar inverter type which is unidirectional, such as shown by the arrow 5, and which transforms a DC voltage at the primary 4a into an alternating voltage at the secondary 4b of said converter 4.

[0023] The secondary 4b of the DC/AC converter 4 is connected via a distribution cable 6 to the network of the supplier 7 and to the cabling network of the industrial site 8. A bidirectional energy meter 9 makes it possible to meter, on the one hand, the quantity of electricity taken from the network of the supplier 7 for the supply of the industrial site 8 when the self-production of energy is insufficient and, on the other hand, the quantity of electricity injected into said network of the supplier 7 when an over-production of electricity that cannot be stored or used on the industrial site 8. Although of similar design, this bidirectional energy meter 9 is entirely independent from the bidirectional energy meter (not shown) installed by the supplier 7 for the purpose of metering the sales price and the purchase price of the electricity.

[0024] Such as shown in figure 1, the photovoltaic installation 1 comprises fork-lift trucks 10. In this figure 1, a single fork-lift truck 10 is diagrammed, the principle however remains identical with several fork-lift trucks 10, according to the number of trucks available for the handling needs on the industrial site 8. The photovoltaic installation 1 comprises a bidirectional AC/DC converter 11 of which the primary 1 la is connected in parallel on the distribution cable 6 via a cable 12, which makes it possible to connect it to the secondary 4a of the DC/AC converter 4. This cable 12 can however be connected in parallel anywhere on the cabling network of the industrial site 8. As long as secondary 1 lb of the bidirectional AC/DC converter 11 is connected to the fork-lift truck 10 via a cable 13 and a connection system 14. As shown by the arrow 15 in this figure 1, the bidirectional AC/DC converter 11 makes it possible either to transform an alternating voltage into direct voltage in the first direction of circulation going from the secondary 4b of the DC/AC converter 4 to the fork-lift

2018200740 31 Jan 2018 truck 10 when the production of solar energy is greater than the need for energy on the industrial site 8, or the transformation of a DC voltage into an alternating voltage in the second direction of circulation going from the fork-lift truck 10 to the industrial site 8 when the production of solar energy is insufficient pour for supplying said industrial site 8.

[0025] Such as shown in figure 1, the photovoltaic installation 1 comprises an automatic device 16 configured to control the bidirectional AC/DC converter 11 in one or the other direction of conversion of the energy according to the production of solar energy and the supply needs of the industrial site 8. For this, the automatic device 16 recovers data from the bidirectional energy meter 9. When the production of solar energy is greater than the electrical need of the industrial site 8, the surplus of energy production should be injected into the network of the supplier 7, as is the case on conventional installations. On the contrary, according to the invention, the bidirectional energy meter 9 transmits this data to the automatic device 16 (as shown by the arrow 17), which activates the bidirectional AC/DC converter 11 (as shown by the arrow 18) so that the surplus of production of solar energy is stored in the rechargeable batteries 19 of the fork-lift trucks 10 rather than be injected into the network of the supplier 7. When the production of solar energy is insufficient for the needs in electricity of the industrial site 8, the bidirectional energy meter 9 detects the need to take energy on the network of the supplier 7, as is the case for conventional installations. On the contrary, according to the invention, the bidirectional energy meter 9 transmits this data to the automatic device 16 which switches the bidirectional AC/DC converter 11 so that the energy stored in the batteries 19 of the fork-lift trucks 10 connected to the photovoltaic installation 1 are restored for the needs in electricity of the industrial site 8, rather than taking this energy on the network of the supplier 7.

[0026] In case of insufficient energy stored in the batteries 19 of the fork-lift trucks 10 connected or in case of need to disconnect the fork-lift trucks 10 for handling operations, the automatic device 16 neutralises the bidirectional AC/DC converter 11 so that the electricity is taken from the network of the supplier 7 for the supply needs of the industrial site 8, in so much as this energy cannot be supplied directly by the photovoltaic panels 2. This also makes it possible to prevent an excessive discharge of the batteries 19 beyond a critical threshold. In case of a maximum charge of the batteries 19 on the fork-lift trucks 10 is reached, the surplus of solar energy produced is then injected into the network of the supplier 7.

2018200740 31 Jan 2018 [0027] The connection system 14 allows for frequent connections and disconnections of a fork-lift truck 10. This connection system 14 comprises a male connector 14a on the first portion 13a of the cable 13 connected to the secondary 1 lb of the bidirectional AC/DC converter 11 and a female connector 14b on the second portion 13b of the cable 13 connected to the fork-lift truck 10. The male 14a and female 14b connectors can be inverted on the first and second portions 13a, 13b of the cable 13, without modification of the operating principle. A resistance with the detection of the presence of the battery (not shown) is integrated into the connection system 14, even in the bidirectional AC/DC converter 11, allows for the charging or discharging of the capacitor integrated into the bidirectional AC/DC converter 11, which prevents the formation of electric arcs during the frequent connections and disconnections of the fork-lift truck 10 for the needs of use.

[0028] In the alternative embodiment of the photovoltaic installation 1 of figure 2, the principle remains identical to that described hereinabove for figure 1. As such there are the solar panels 2, the DC/AC converter 4, the bidirectional energy meter 9, the network of the supplier 7 and the industrial site 8 with the same connection configuration via cables 3,6. Contrary to the embodiment of figure 1, the bidirectional AC/DC converter 11 and the automatic device 16 are on-board the fork-lift truck 10. This design therefore requires having one bidirectional AC/DC converter 11 and one automatic device 16 per fork-lift truck 10. The secondary 1 lb of the bidirectional AC/DC converter 11 is connected to the battery 19 of the fork-lift truck 10 via the cable 13. While the primary 1 la of the bidirectional AC/DC converter 11 is connected indirectly to the secondary 4b of the DC/AC converter 4 via the cable 12 and of the connection system 14, said cable 12 being connected in parallel on the distribution cable 6 or anywhere on the distribution network of the industrial site 8. This connection system 14 comprises, as hereinabove, a male connector 14a and a female connector 14b making it possible to frequently connect and disconnect the two portions 12a, 12b of the cable 12 for a use of the fork-lift truck 10. The connection system 14 or the bidirectional AC/DC converter 11 also comprises a resistor with detection of the presence of the battery (not shown) making it possible to charge or discharge the capacitor integrated into the DC/AC converter 4 in such a way as to prevent electric arcs during the connecting and disconnecting of the fork-lift truck 10.

[0029] According to these two alternatives of figures 1 and 2, the transmission of metering data of the energy shown by the arrow 17 of the bidirectional energy meter 9 to the automatic

2018200740 31 Jan 2018 device 16 will preferably be carried out via a wireless connection. The transmission of the control data shown by the arrow 18 between the automatic device 16 and the bidirectional AC/DC converter 11 is more preferably carried out via a wireless connection.

[0030] As such the invention makes it possible to use the production of solar energy for a self-consumption on the industrial site 8, by limiting to the maximum the flow of electricity on the network of the supplier 7. This also allows for a daily discharging and recharging of the batteries 19 on the fork-lift trucks 10, which improves their service life.

[0031] The connection in parallel of the bidirectional AC/DC converter or converters 11 with regards to the distribution network of the industrial site 8 advantageously makes it possible to carry out frequent connections and disconnections of the fork-lift trucks 10 anywhere on said distribution network, without any incidence on then normal operation of the industrial site 8.

[0032] The detailed description that precedes of the two embodiments of the invention do not have any limiting nature. On the contrary, it has for objective to remove any imprecision as to the scope thereof. As such, alternatives can be considered in the framework of the invention.

[0033] By way of example, in figure 3, the photovoltaic installation 1 corresponds to that shown in figure 1, the preceding description with regards to figure 1 therefore applies for this figure 3. The only difference concerns the bidirectional AC/DC converter 11 which is implemented by means of a charger 110 of a fork-lift truck, of an inverter 111 and a switch 112. The charger 110 plays the role of an AC/DC converter, with the latter making it possible to transform an alternating voltage coming from the secondary 4b of the DC/AC converter 4, into a DC voltage supplying the fork-lift truck 10, as diagrammed by the arrow 15a, when the production of solar energy is greater than the need for energy on the industrial site 8. The inverter 111 makes it possible to convert a DC voltage coming from the fork-lift truck 10, into an alternating voltage supplying the industrial site 8, as diagrammed by the arrow 15b, when the production of solar energy is insufficient to supply said industrial site 8. The switch 112 is for example of the electromechanical type. This switch 112 makes it possible to switch either to the charger 110 or to the inverter 111, with the automatic device 16 controlling the ίο

2018200740 31 Jan 2018 switch 112 in one or the other direction of conversion of the energy according to the production of solar energy and the supply needs of the industrial site 8.

[0034] Another alternative can also be considered that combines the characteristics of figures 2 and 3, in which case the bidirectional AC/DC converter 11, implemented by means of the charger 110, of the inverter 111 and of the switch 112, and the automatic device 16 are on-board the fork-lift truck 10.

Claims (9)

1. Photovoltaic installation (1) for an industrial site (8) comprising:

- at least one photovoltaic panel (2) for the production of solar energy,

- a DC/AC converter (4) comprising a primary (4a) and a secondary (4b), with the primary (4a) being connected to at least one photovoltaic panel (2),

- a bidirectional energy metering device (9) connected, on the one hand, to the secondary (4b) of the DC/AC converter (4) and, on the other hand, to the network of a supplier of electricity (7), characterised in that it comprises:

- at least one bidirectional AC/DC converter (11) comprising a primary (11a) and a secondary (1 lb), with the primary (11a) being connected in parallel to the secondary (4b) of the DC/AC converter (4);

- at least one control device (16) configured to control the bidirectional AC/DC converter (11) according to the metering data supplied by the bidirectional energy metering device (9);

- at least one fork-lift truck (10) comprising a rechargeable battery (19) connected to the secondary (lib) of the bidirectional AC/DC converter (11).

2. Photovoltaic installation (1) according to claim 1, which comprises a single bidirectional AC/DC converter (11) and a single control device (16), with first means of removable connection (13, 14) being arranged between the battery (19) of the at least one fork-lift truck (10) and the secondary (lib) of the bidirectional AC/DC converter (11).

3. Photovoltaic installation (1) according to claim 2, wherein the first means of removable connection (13, 14) are configured to prevent electric arcs during the connecting or disconnecting of a fork-lift truck (10) with regards to the secondary (lib) of the bidirectional AC/DC converter (11).

4. Photovoltaic installation (1) according to claim 3, wherein the first means of removable connection include a male connector (14a) and a female connector (14b) with one connected to the fork-lift truck (10) and the other to the secondary (1 lb) of the bidirectional AC/DC converter (11), and first resistive means configured to charge or discharge first capacitive means on said converter (11).

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5. Photovoltaic installation (1) according to claim 1, which comprises as many bidirectional AC/DC converters (11) and controls devices (16) as there are fork-lift trucks (10), with said elements being on-board said trucks, with second means of removable connection (12, 14) being arranged between each fork-lift truck (10) and the secondary (4b) of the DC/AC converter (4).

6. Photovoltaic installation (1) according to claim 5, wherein the second means of removable connection (12, 14) are configured to prevent electric arcs during the connecting or disconnecting of a fork-lift truck (10) with regards to the secondary (4b) of the DC/AC converter (4).

7. Photovoltaic installation (1) according to claim 6, wherein the second means of removable connection include a male connector (14a) and a female connector (14b) connected one to the truck (10) and the other to the secondary (4b) of the DC/AC converter (4), and second resistive means configured to charge or discharge second capacitive means on said converter (4).

8. Photovoltaic installation (1) as claimed in any preceding claim, wherein the control device (16) is comprised of an automatic device.

9. Photovoltaic installation (1) according to one of the preceding claims, wherein each bidirectional AC/DC converter (11) is comprised of a charger (110), of an inverter (111) and of a switch (112), with the charger (110) and the inverter (111) being mounted in parallel between them and connected in parallel on the secondary (4b) of the first DC/AC converter (4) by the intermediary of the switch (112) making it possible to switch either to the charger or to the inverter, with said switch being controlled by the control device (16).