ITMI20112178A1 - POWER LIMITATION SYSTEM ENTERED INTO NETWORK BY RENEWABLE SOURCES - Google Patents

Description

Title: "System for limiting the power fed into the grid by renewable source plants".

DESCRIPTION

Field of invention

The present invention refers to a system for limiting the power fed into the grid by one or more renewable source plants, in accordance with the preamble of claim 1.

State of the art

In accordance with the state of the art, renewable source plants are known, such as, for example, plants equipped with photovoltaic panels, wind turbines or the like capable of producing and feeding the power produced by them into an electrical network.

However, as is known, an electricity grid, such as the Italian one, does not support Γ connection of renewable energy plants with power greater than the capacity established by the electricity service manager for each specific point, i.e. a power established during the investigation by the managing body which imposes, on the basis of the physical limit of the network, the maximum power that can be connected to each specific point.

This entails Γ impossibility of installing renewable source plants greater than the maximum power established during the preliminary investigation phase by the managing body.

However, this limit to the maximum power that can be fed into the grid deprives the owner of the renewable sources plant from obtaining greater economic advantages due to the construction of larger plants in compliance with the limit imposed by the managing body of the electricity grid.

Technical problem

From the foregoing, the need emerges to have a suitable system to limit the power fed into the grid from renewable source plants and dependent on the actual needs of the electricity grid.

Technical Solution

It is therefore necessary, to allow the connection of plants with greater power in compliance with that imposed by the grid, to have a system that allows the dissipation of the excess energy produced by the renewable energy plant in accordance with the input limits. of power established by the managing body during the preliminary investigation.

This purpose is achieved by a system for limiting the power fed into the grid from renewable source plants in accordance with claim 1.

Beneficial effects

Thanks to the present invention it is possible to obtain a system capable of injecting into the electric network a determined and constant quantity of power produced by a renewable source plant.

Moreover, thanks to the present invention, it is possible to feed into the grid the quantity of energy that the electric grid can actually absorb in a given instant of time.

Finally, according to a further advantageous aspect of the present invention, thanks to the particular implementation of the inventive system it is possible to limit the disturbances introduced into the electrical network.

Brief description of the drawings

Further characteristics and advantages of the system according to the present invention will result from the description given below of a preferred embodiment thereof, given by way of non-limiting example, with reference to the attached figure 1 which represents a schematic view of a possible form of realization of the system capable of injecting a determined quantity of energy produced by the renewable source plant into the electricity network, in accordance with the present invention.

Detailed description

With reference to the annexed figure 1, 1 indicates in its generality a system equipped with a renewable source plant 2 structured to generate a power Q.

The purpose of the inventive system 1 is to introduce a certain amount of power Q ', part or fraction of the power Q generated by the plant 2 into an electrical network 3.

It should immediately be noted that regret 2 takes the form of a system that may include photovoltaic panels, wind generators and / or a combination of the same capable of producing electricity Q.

System 1 also includes:

- means of measurement 4 of the energy produced by the renewable sources plant 2;

- processing and control means 5 e

- dissipation means 6 to dissipate a certain amount of energy Q produced by the renewable source system 2 to enter the power Q 'into the electricity grid 3.

In particular, the measuring means 4 are placed in signal communication with the regret 2 and with the processing and control means 5.

Preferably these measuring means 4 are arranged downstream of the plant 2 and upstream of the processing and control means 5.

To this end, the measuring means 4 generate an electrical signal SI identifying the value of the power, energy and / or electrical quantities generated by the plant 2 and the processing and control means 5 are configured to receive and process this electrical signal. YES.

In one embodiment, the measuring means 4 take the form of Amperometric Transformers (TA), Voltometric Transformers (TV) and data communication through communication protocols (Modbus or similar).

The processing and control means 5 preferably take the form of a Programmable Logic Controller (PLC) or a personal computer with suitable data input and output interfaces.

The system 1 comprises second energy measurement means 7 arranged upstream of the electricity network 3, which are configured to generate a second signal S2 identifying the quantity Q 'of energy that can be input (or absorbed) from the electricity network 3.

In other words, the S2 signal represents the energy value Q 'that the electricity network 3 is actually able to absorb at that moment.

In one embodiment, the measuring means 7 take the form of Amperometric Transformers (TA), Voltometric Transformers (TV) and data communication through communication protocols (Modbus or similar).

The dissipation means 6 are arranged in signal communication with the regression 2 and with the processing and control means 5 and are suitably sized to dissipate a determined quantity of energy Δ produced by the system 2, with the aim of guaranteeing an injection of power less than or equal to the power limit imposed by the managing body.

Advantageously, according to a peculiar aspect of the present invention, we have that:

- the dissipation means 6 are constant dissipation means which, when suitably connected, can provide a variable load value to the electrical network 3

- the processing and command means 5 are configured to command at least partially said dissipation means 6 in closing or opening as a function of the signals S1 and S2, that is, as a function of the value of power supplied Q and measured by the measuring means 4 and of the value Q 'can actually be fed into the electrical network 3 to dissipate the aforementioned predetermined energy Δ in compliance with the imposed limits.

In this way it is possible to dissipate the amount Δ of energy produced by the renewable source plant 2 and the remaining amount of this predetermined amount of energy produced can be fed into the electricity grid 3.

In other words, it is possible to activate (or deactivate) at least partially or totally, through the processing and control means 5, the dissipative means 6 which, being at variable load, can be adapted (i.e. dimensioned) to the quantity of energy Q 'actually receivable. by the electrical network 3 to dissipate that predetermined quantity of energy Δ which must not be fed into the electrical network 3.

Therefore the predetermined amount of energy Δ to be dissipated by the dissipation means 6 is a function of the energy value Q generated by the system and the energy Q ’that can be fed into the electrical network 3.

For example, the predetermined quantity of energy Δ to be dissipated can be even calculated according to the following formula:

A = Q- Q \

Alternatively, the quantity Δ to be dissipated by the dissipation means 6 can be set by the user of the system 1.

It should be noted that the predetermined quantity Δ is variable between zero and the entire value of energy produced by the plant 2.

In other words it is possible, by varying the load value of the dissipative means 6, that the system 1 of the present invention is capable of injecting into the electrical network 3 a value between the maximum value that can be produced by the system 2 or not injecting energy at all. in the power grid 3.

The dissipative means 6 are therefore implemented and sized in such a way that they can dissipate at least the maximum power value Q that can be produced by the system 2

According to a characteristic of the present system 1, the dissipation means 6 comprise a plurality of constant resistive banks of similar and / or different sizes, i.e. a group of such plurality of resistive banks has its own constant and different dimension, each group being able to comprise one or more resistive elements.

For example, a group of banks can be composed of one or more resistors having a value equal to 1KOhm and another group can be composed of one or more resistors having a value equal to 64KOhm.

According to an advantageous aspect of the present invention, it should be emphasized that the processing and control means 5 sequentially select one or more of said resistive banks as a function of the value of the signal S1 and the signal S2.

For example, according to a particularly effective selection strategy, the means of 5 first select the resistive elements with the largest resistance value in order to select, i.e. to add to those already selected, further resistances with a smaller value as long as there is no reached a size of overall resistance necessary and sufficient to dissipate the predetermined value Δ.

In other words, the processing and control means 5 first activate the higher size resistors (for example those equal to 64KOhm) and gradually activate those of lower size (for example those equal to 1KOhm) as long as the load realized by the dissipative means 6 it is not sufficient to dissipate the predetermined value Δ.

Thanks to the aforementioned strategy for activating the resistive elements, it is possible to limit the disturbances that are introduced into the electrical network 3.

In order to select the banks necessary and sufficient to dissipate the predetermined amount of energy Δ, the processing and control means 5 comprise a plurality of switches 8 which can be activated by means of a respective activation signal Satt suitably generated by the processing and control means 5 in operation of the value of the signals SI and S2.

Each of these switches can be connected to a respective resistive element as a function of the state of said activation signal Satt.

In other words, the processing and control means 5 process the signals S1 and S2 to command the necessary number of resistive elements 6 in closing or opening, by means of the appropriate closing or opening of the respective switches controlled by the Satt signal, in order to guarantee the 'injection into the electricity grid 3 of the quantity Q' of the power Q produced by the plant 2.

Should the values represented by the signals SI and / or S2 change, the processing and control means 5 modify the number of resistive elements 6 which must be selected by opening or closing the respective switches.

This makes it possible to dynamically adapt the system 1 to the changed meteorological or operating conditions (and therefore to the variability of production of the supplied power Q) but to keep constant the power value Q 'that can be fed into the electricity grid 3 if, also the conditions of injection of the latter have not undergone any changes.

Obviously, a person skilled in the art, in order to meet contingent and specific needs, will be able to make numerous changes and variations to the limitation system according to the invention described above, all however contained within the scope of protection of the invention as defined by the following claims.

Claims (8)

CLAIMS 1. System for limiting the power fed into a grid (3) by a renewable source plant (2), said system comprising: - a renewable energy plant (2) which can be connected to said electricity grid (3), - first measuring means (4) of the energy produced by said renewable source plant, said measuring means being placed in signal communication with said renewable source plant (2) to generate a first signal (SI) identifying the power supplied (Q) from said plant (2), - processing and command means (5) to receive at the input said first signal (SI) and a second signal (S2) identifying a quantity of energy that can be input (Q ') in said electrical network (3); characterized in that it comprises dissipation means (6) for dissipating a determined quantity of energy (Δ) produced by said renewable source plant (2) and arranged in signal communication with said renewable source plant (2) and said means of processing and command (5), the latter being configured to command the closing or opening at least partially said dissipation means (6) as a function of said first signal (SI) and said second signal (S2) so as to dissipate said predetermined quantity of energy (Δ) produced. 2. System according to claim 1, wherein said dissipation means (6) have variable load and comprise a plurality of resistive banks of different sizes, said processing and control means (5) sequentially selecting one or more than said resistive banks as a function of said first signal (SI) and said second signal (S2). 3. System according to claim 2, wherein said processing and control means (5) are configured to first select the resistive banks of larger size and subsequently resistive banks of smaller size. System according to any one of the preceding claims 2 to 3, wherein said processing and control means (5) comprise a plurality of switches (8) each of which is associated with a respective resistive bank, said plurality of switches being in signal communication with said processing and control means (6) and controllable by the latter by means of an activation signal (Satt). 5. System according to any one of the preceding claims from 2 to 4, in which said resistive bank of smaller size is equal to 1KOhm and said resistive bank of larger size is equal to 64KOhm. 6. System according to claim 1, comprising second energy measuring means (7) arranged upstream of said electrical network (3), configured to generate said second signal (S2) identifying said quantity of energy (Q ' ) which can be fed into said electrical network (3). System according to claim 1, wherein said processing and control means (5) are a Programmable Logic Controller. 8. System according to claim 1, wherein said renewable source plant comprises solar panels, wind generators and / or the like.