Technical Field

The present invention relates to a system for the control of electric energy, in particular a system for the smart control of the electric energy of a domestic/residential type of user point.

Background Art

Recently, the more widespread use of plants for the production of energy from renewable sources, such as, e.g. photovoltaic and/or wind power plants, has laid the foundations for the development of a“smart” type of energy distribution, also called“smart grid”, which, in addition to the public network for the distribution of electric energy, comprises a network of peripheral nodes, some of which small, from which the flows of energy travel in a bidirectional way to and from the public distribution network.

Peripheral nodes, such as homes for example, usually use units for the production of renewable energy to:

transfer the renewable energy produced directly in the home to power the loads;

feed the renewable energy produced into the public network for the distribution of electric energy;

store the renewable energy produced for subsequent use.

Depending on the type of use of the renewable energy produced, two types of peripheral nodes mainly exist:“grid-connected” or“stand-alone”.

In the first case,“grid-connected” means a system wherein the unit for the production of renewable energy is connected in parallel to the public network for the distribution of electric energy.

Typically, a“grid-connected” system comprises:

a plurality of photovoltaic panels (or other devices for the production of renewable energy) adapted to transform solar energy into electric energy; a system of storage by means of accumulators which conserves the energy not consumed for use when the photovoltaic panels do not produce energy (e.g. at night); and an inverter equipped with a DC- AC converter block to stabilize the energy produced or stored and to transform it at the voltage and frequency of the loads (in the case of transfer of panels/accumulators towards the loads) or at the voltage and frequency imposed by the electric energy distribution network operator (in the case of transfer of panels/accumulators to the network).

During a normal day of use, of course, various different scenarios can occur in the production/distribution of energy in a user point.

For example, if the energy absorption of the home is greater than the electric energy produced or stored by the photovoltaic panels, the electric energy distribution network will be expected to feed the excess demand into the home, together with that produced by the panels. In such case, the user will pay the excess energy to the distribution network operator.

Diversely, if the energy absorption of the home is lower than the electric energy produced by the photovoltaic panels, the excess energy can be stored in the batteries or be fed into the public distribution network through the“exchange on the spot” system and calculated through special bi-directional meters. In the latter case, the distribution network operator may pay or compensate for the sale of energy produced by the photovoltaic panels.

With regard to the“stand-alone” peripheral nodes, it should be noticed that the latter, unlike the“grid connected” type, are isolated from the electric energy distribution network and have accumulators that store the energy not consumed to use it when the photovoltaic panels do not produce energy (e.g., at night).

In recent years, with the increasing presence of electric vehicles in the country, the“grid connected” systems can be equipped with dedicated connections to connect electric cars to the public distribution network. These systems, commonly called“vehicle to grid” or“V2G” do in fact permit the addition of a further accumulator (the car battery), the energy of which can flow bi directionally to and from the public distribution network, to make it possible not only to charge the battery of the electric vehicle but, if necessary, for dispatching reasons, to return the electric energy previously stored in the battery of the electric vehicle to the network.

In consideration of the different and numerous sources of energy to be controlled in the“grid connected” type systems, it is increasingly difficult to control dynamically and in real time the available energy flows according to the specific convenience for each particular moment of the day. It follows that the storage of energy and/or the redistribution of the same in the public network or inside the home must be controlled effectively without affecting the overall energy balance.

Description of the Invention

One object of the present invention is therefore to provide a system for the control of electric energy with functional characteristics such as to meet the above requirements and at the same time to overcome the problems mentioned with reference to the prior art.

This object is achieved by a system for the control of electric energy in accordance with claim 1.

Brief Description of the Drawings

Further characteristics and the advantages of the system for the control of electric energy according to the present invention will emerge from the following description of its preferred embodiments, given by way of an indicative and non-limiting example, with reference to the attached illustrations, wherein:

- Figure 1 is a connection diagram showing a first embodiment of the system according to the present invention;

- Figure 2 is a connection diagram showing a second embodiment of the system according to the present invention,

- Figure 3 is a connection diagram showing a third embodiment of the system according to the present invention;

- Figure 4 is a connection diagram showing a fourth embodiment of the system according to the present invention.

Embodiments of the Invention

With particular reference to these figures, reference numeral 1 globally indicates an electric energy distribution system in accordance with the present invention.

The system 1 comprises:

at least one accumulator 8 for the accumulation of electric energy. Preferably, the accumulator 8 can comprise at least one direct current battery, e.g. of the lithium-ion or nickel-cadmium type;

at least one connection section 13 for the electric connection to the electric energy distribution network 3. The connection section 13, e.g. consists of an electric connection node, i.e. in a simple point of connection to the electric energy distribution network 3, or in a more complex electronic device, such as an electric panel, an electric circuit comprising multiple nodes, or the like;

at least one charging point 14 for the connection to an electric vehicle 9 provided with a rechargeable battery. The charging point 14 in turn comprises:

at least one AC/DC converter 5 which is adapted to place the electric vehicle 9 in electric communication with the connection section 13. The AC/DC converter 5 can be of the unidirectional type (in which case the electric current drawn from the electric energy distribution network 3 can be used to charge the battery of the electric vehicle 9) or of the bidirectional type (in which case it is possible to draw the electric current from the electric energy distribution network 3 to charge the battery of the electric vehicle 9 and, if necessary, draw electric current from the battery of the electric vehicle 9 and feed it into the electric energy distribution network 3); and

at least one bidirectional DC/DC converter 7 which is adapted to place the electric vehicle 9 in electric communication with the accumulator 8. The fact that the DC/DC converter 7 is of the bidirectional type makes it possible to draw electric current from the accumulator 8 to charge the battery of the electric vehicle 9 and, if necessary, draw electric current from the battery of the electric vehicle 9 to charge the accumulator 8. One of the objects of the DC/DC converter 7 is to convert the DC voltage of the accumulator 8 into a DC voltage suitable for the battery of the electric vehicle 9 and vice versa.

Advantageously, the system 1 of the present invention can operate in different conditions according to the environmental conditions, according to the user's need and/or according to public energy redistribution needs.

In the case in point, and as will be explained in detail below in the present description, the system 1 can operate under at least one of the following conditions, which can also be combined with each other:

condition of drawing public energy from the electric energy distribution network 3;

condition of drawing energy from the battery of the electric vehicle 9;

condition of drawing energy from the accumulator 8;

condition of feeding energy into the electric energy distribution network 3; condition of charging the battery of the electric vehicle 9;

condition of storing energy in the accumulator 8.

By means of the charging point 14 in fact, the electric current can be:

drawn from the electric energy distribution network 3 (condition of drawing public energy) to power the electric vehicle 9 (condition of charging the battery of the electric vehicle 9) and/or the accumulator 8 (condition of storing energy);

drawn from the accumulator 8 (condition of drawing energy from the accumulator 8) to charge the electric vehicle 9 (condition of charging the battery of the electric vehicle 9) and, if the AC/DC converter 5 is of the bidirectional type, to feed electric energy into the network for dispatching purposes (condition of feeding energy into the network);

drawn from the electric vehicle 9 (condition of drawing energy from the battery of the electric vehicle 9) to charge the accumulator 8 (condition of storing energy) and, if the AC/DC converter 5 is of the bidirectional type, to feed electric energy into the network for dispatching purposes (condition of feeding energy into the network). The AC/DC converter 5 comprises:

a first alternating section 5a connected to the connection section 13; and a second direct section 5b connectable to the electric vehicle 9.

The DC/DC converter 7 comprises:

a first direct section 7a connected to the accumulator 8; and

a second direct section 7b connectable to the electric vehicle 9.

In the context of the present treatise, when it is said that the second direct section 5b of the AC/DC converter 5 and the second direct section 7b of the DC/DC converter 7 are connectable to the electric vehicle 9 one should understand that such a connection is of a non-permanent type.

It is easy to appreciate, in fact, that the electric vehicle 9 can be freely connected to and disconnected from the charging point 14 to allow the separation of the electric vehicle 9 from the system 1 and its use as a means of transport.

Figure 1 shows a first embodiment of the system 1, wherein the second direct section 5b of the AC/DC converter 5 and the second direct section 7b of the DC/DC converter 7 are connected to a common connecting node 15 connectable to the electric vehicle 9 along a connecting stretch 16.

In the embodiment shown in Figure 1, the AC/DC converter 5 is of the unidirectional type and can only be crossed by the electric energy coming from the electric energy distribution network 3, through the connection section 13, and cannot flow in the opposite direction.

However, as already mentioned, the possibility cannot be ruled out of the AC/DC converter 5 being of the bidirectional type.

Figure 2, on the other hand, shows a second embodiment of the system 1 which differs from the first one by the fact that the charging point 14 comprises at least one bidirectional auxiliary DC/DC converter 24, positioned along the connecting stretch 16.

The auxiliary DC/DC converter 24 e.g. comprises:

a first direct section 24a connected to the connecting node 15; and a second direct section 24b connectable to the electric vehicle 9. In the second embodiment, therefore, there is a further DC/DC converter which permits sizing the components, i.e., the AC/DC converter 5, the DC/DC converter 7 and the auxiliary DC/DC converter 24, in a particularly convenient way according to the real needs of the system 1, e.g., in terms of electric power to be transferred through the charging point 14 and of transfer efficiency.

In a similar way to what is shown in Figure 1, in the embodiment shown in Figure 2, the AC/DC converter 5 is also of the unidirectional type and can only be crossed by the electric energy coming from the electric energy distribution network 3, through the connection section 13, and cannot flow in the opposite direction.

In this case too, however, it is possible to provide for an AC/DC converter 5 of the bidirectional type.

Figure 3 shows, on the other hand, a third embodiment of the system 1 which differs from the first one by the fact that the second direct section 5b of the AC/DC converter 5 and the second direct section 7b of the DC/DC converter 7 coincide with each other.

In this embodiment, in actual facts, the AC/DC converter 5 and the DC/DC converter 7 consist of a three-port hybrid inverter and the AC/DC converter 5 is of the bidirectional type, thus allowing crossing the electric energy either from or towards the electric energy distribution network 3.

Finally, Figure 4 shows a fourth embodiment of the system 1, which shows a more articulated implementation of the embodiment of Figure 1, to which, however, reference should be made as regards the detailed description of the AC/DC converter 5 and of the DC/DC converter 7, with the variant, already previously provided for, that the AC/DC converter 5 of the embodiment in Figure 4 be of a bidirectional type.

The system 1 shown in Figure 4 is associated with a user point (e.g. a dwelling house) comprising one or more loads 12.

The connection section 13 in fact, is associable with at least one load 12 of the user point and is adapted to send electric energy to the load itself.

For this purpose, for example, the system 1 comprises a distribution module 11 connected to the connection section 13 and provided with one or more electric connectors 4 to which the loads 12 are associable to power them.

Preferably, the distribution module 11 also comprises a meter to count the flow of electric energy circulating in the user point.

The system 1 also comprises at least one unit for the production of renewable energy 6 and at least one inverter device 2 which is adapted to place in electric communication:

the unit for the production of renewable energy 6 with the connection section 13; and

the unit for the production of renewable energy 6 with the accumulator 8 and with the DC/DC converter 7.

In the rest of the present description and in the subsequent claims“units for the production of renewable energy” shall be meant to indicate units for the production of energy by wind, geothermal, hydroelectric, marine, and/or solar systems.

A unit for the production of renewable energy may therefore comprise, e.g., solar/photovoltaic panels, water turbines, windmills, etc.

In the example shown in Figure 4, the unit for the production of renewable energy comprises a plurality of photovoltaic panels 6.

The inverter device 2 comprises:

a first direct section 2a connected to the unit for the production of renewable energy 6;

a second alternating section 2b connected to the connection section 13; and a third direct section 2c connected to the accumulator 8 and to the DC/DC converter 7.

Preferably, the system 1 of the present invention comprises a switching node 10 connected to the accumulator 8, to the inverter device 2 and to the DC/DC converter 7 to direct, if necessary, the energy flows in a bidirectional way between the accumulator 8 and the DC/DC converter 7, between the DC/DC converter 7 and the inverter device 2 device or between the accumulator 8 and the inverter device 2. Advantageously, the presence of the loads 12 and of the unit for the production of renewable energy 6 enable the system 1 of the present invention to operate in even more diverse operating conditions depending on needs.

In addition to operating under the already mentioned conditions, i.e.:

condition of drawing public energy from the electric energy distribution network 3;

condition of drawing energy from the battery of the electric vehicle 9;

condition of drawing energy from the accumulator 8;

condition of feeding energy into the electric energy distribution network 3; condition of charging the battery of the electric vehicle 9;

condition of storing energy in the accumulator 8.

The system 1 of Figure 4 can also operate under the following conditions:

condition of drawing renewable energy;

condition of powering the loads 12;

condition of sale of the renewable energy.

Through the connection section 13, the user, in accordance with the present invention, is connected to the public electric energy distribution network 3, which typically supplies alternating current energy.

It follows, therefore, that the alternating current coming from the electric energy network 3 (condition of drawing energy from the public network) is intended to supply the loads 12 of the user point (condition of powering the loads 12).

Still through the connection section 13, the user point in accordance with the present invention is also connected to the photovoltaic panels 6 which provide for renewable energy typically in direct current.

The renewable energy produced by the photovoltaic panels 6 can therefore power the loads 12 through the inverter device 2 meant to transform it from direct to alternating current (condition of drawing renewable energy and condition of powering the loads 12).

In case of excess production of renewable energy, this can be stored in the accumulator 8 (condition of drawing renewable energy and condition of storing energy). Optionally, the inverter device 2 is also intended to convey the renewable energy produced by the photovoltaic panels 6 to the electric energy distribution network 3 (condition of sale of renewable energy).

Still through the inverter device 2, the energy stored in the accumulator 8 can be conveyed to the electric energy distribution network 3 without passing through the charging point 14.

Through the charging point 14, furthermore, the electric energy produced by the photovoltaic panels 6 can be conveyed to the electric vehicle 9 to charge it (condition of drawing renewable energy and condition of charging the battery of the electric vehicle 9).

If the AC/DC converter 5 is of the bidirectional type, it is possible, if necessary, to provide for the drawing of the energy stored in the electric vehicle 9 so as to convey it to the electric connectors 4 in order to power the loads 12 (condition of drawing energy from the battery of the electric vehicle 9 and condition of powering the loads 12).

In other words, the battery of the electric vehicle 9 can be recharged, if necessary, by means of the alternating current coming from the public network 3, the renewable energy coming from the photovoltaic panels 6 and/or the stored energy coming from the accumulator 8.

Similarly, the accumulator 8 may be charged, if necessary, by means of the alternating current coming from the public network 3, the renewable energy coming from the photovoltaic panels 6 and/or the energy coming from the battery of the electric vehicle 9.

The loads 12, instead, can be powered by the alternating current coming from the public network 3, the renewable energy coming from the photovoltaic panels 6, the stored energy coming from the accumulator 8 and/or the energy coming from the battery of the electric vehicle 9.

Finally, for reasons of dispatching and/or selling energy, it is possible to feed renewable energy coming from the photovoltaic panels 6, the stored energy coming from the accumulator 8 and the electric energy coming from the battery of the electric vehicle 9 into the electric energy distribution network 3. For the control and entire management of the energy flows through the system 1, the charging point 14 comprises at least one energy control device 18 or EMS (Energy Management System).

The energy control device 18 is placed in signal communication, by means of e.g. communication wiring of the bus type, at least with the AC/DC converter 5, with the DC/DC converter 7, with the electric energy distribution network 3 and with the accumulator 8.

Preferably, the energy control device 18 can be placed in signal communication also with other components of the system 1.

In the embodiment shown in Figure 4, for example, the energy control device 18 is arranged in signal communication also with two auxiliary counters 19, of the bidirectional type, which count the flow of electric energy circulating from and towards the electric vehicle 9.

Even if not shown in Figure 4, the energy control device 18 can be usefully placed in signal communication even with the meter intended to count the flow of electric energy circulating in the loads 12.

In the embodiment shown in Figure 4, moreover, the energy control device 18 is placed in signal communication also with the inverter device 2, to detect and manage the parameters relating to the renewable energy produced by the photovoltaic panels 6.

Still with reference to Figure 4, the energy control device 18 is placed in signal communication, e.g. by means of non-wiring connection (Internet, GSM, etc.) also with a remote operating center 20, which for example can transmit data relating to the electric energy distribution network 3.

The energy control device 18 is adapted to control the AC/DC converter 5 and the DC/DC converter 7 according to some operating parameters relating at least to the accumulator 8 and to the electric energy distribution network 3.

More in particular, the energy control device 18 is intended to monitor and process the energy flows circulating between the components of the system 1, e.g., in order to:

obtain the highest energy efficiency in real time both according to the type and quantity of absorption of the loads, and according to the demand for the redistribution of energy by the public network, and according to the threshold of intervention of any devices for limiting the power exchanged from and to the electric energy distribution network 3;

- control the production of renewable energy;

control network services, comprising the drawing and feed-in of electric energy from and to the electric energy distribution network 3;

control the energy consumed by the loads 12.

The energy control device 18 is only shown in the embodiment in Figure 4, which is more complete and articulated; it is easy to appreciate, however, that a simplified energy control device 18 can also be envisaged in the embodiments shown in Figures 1-3.

As can be appreciated from what has been described, the system for the control of electric energy according to the present invention makes it possible to satisfy the needs and overcome the drawbacks referred to in the introductory part of the present description with reference to the prior art.

Obviously, the embodiments and the variants described and illustrated so far are to be considered purely as an example and an expert in the field, to meet contingent and specific needs, can make numerous changes and variations to the system for the control of electric energy according to the invention described above, comprising for example the combination of these embodiments and variants, all of which are contained within the scope of protection of the invention as defined by the following claims.