ITBA20130011A1 - CONTROL MODULE AND RELATED ELECTRONIC CIRCUITS, FOR THE AUTONOMOUS AND AUTOMATIC SELECTION OF THE SOURCE OF ELECTRIC SUPPLY IN A PLANT CONNECTED TO THE NATIONAL NETWORK AND TO A CENTRAL UNIT FOR THE PRODUCTION OF ELECTRICAL ENERGY FROM SOURCES - Google Patents

Description

Control module and related electronic circuits, for the autonomous and automatic choice of the source of electricity supply in a plant connected both to the national grid and to a power plant for the production of electricity from renewable sources, as well as for the management of the accumulators of these 'last.

The invention consists of a control module that can be integrated into electrical power plants connected both to the 220 V national grid and to plants for the production of energy from renewable sources, capable of making the autonomous and automatic choice of the source of electricity supply. of the connected utilities, that is able to produce an automatic changeover between one or the other power source according to a series of conditions and parameters which can be partly programmed; it also manages the energy accumulators that are part of the power plant for the production of energy from renewable sources in the best possible way, in order to optimize their use and maximize their life cycle.

As is well known, electricity is mainly produced by transformation starting from a primary energy source; suitable power plants are used for this purpose which operate starting from different energy carriers.

The electricity produced is then transported and distributed through suitable networks, so as to make it easily available for the most disparate uses, in the form of alternating current at 220 V.

An alternative to the production of electricity by transforming a primary energy, is offered by the direct exploitation of so-called renewable energies, ie energies which by their intrinsic characteristic are regenerated at least at the same speed with which they are consumed or are not "exhaustible. "in the" human "time scale (source wikipedia).

They are commonly considered renewable energies, such as solar, wind, tidal energy and others.

Each of the aforementioned renewable energies can be exploited by means of suitable means or systems for the production of electricity.

An example of this is the photovoltaic panel systems which exploit the solar energy incident on them, converting it into electricity to be used directly on site or to be fed into the national distribution network, after conversion into alternating electricity.

In the first case it is customary to indicate this type of system with the term â € œstand-aloneâ €, to indicate an â € œis-aloneâ € system not connected to any distribution network.

In the second case, the plants are defined as â € œgrid-connectâ €, indicating the fact that they are connected to an existing distribution network, into which the electricity they produce is injected.

In a stand-alone system, the utilities connected to it are electrically powered only by the energy produced and stored by the system; this means that in case of unavailability of renewable energy, or in case of exhaustion of the electrical energy stored in suitable accumulators, the utilities cannot function because they are not powered.

In grid-connect systems, the utilities are instead electrically powered only by the national grid and are in no way connected to the photovoltaic system, that is, they cannot directly exploit the electricity produced by the photovoltaic system.

The limits and drawbacks of these known types of plants therefore appear evident: in the case of stand-alone plants there is a risk of not being able to use the utilities connected to the plant if the appropriate renewable energy is not available (wind, sun etc.), or the electrical energy reserve accumulated during plant operation is exhausted; the latter case can, for example, occur for the following reasons:

Photovoltaic panels of number and / or size unsuitable for the production of the overall electricity requirement;

Accumulators of number and / or capacity unsuitable for the storage of electrical energy commensurate with the overall requirement;

Limited availability of renewable energy, therefore unable to sufficiently recharge the batteries and / or satisfy the overall electricity requirement (due for example to seasonal, climatic and / or geographical conditions). A further drawback of stand-alone systems is represented by the fact that in them the accumulators intended to store the electricity produced are used without any logic aimed at safeguarding their efficiency and duration (in fact, it would be necessary to avoid the continuous total discharge, or partial recharge etc.). In the case of grid-connect systems, on the other hand, it is impossible to power the users with self-produced electricity from one's own renewable energy system; due to this, that is to say, the fact that all the users are electrically powered only and exclusively by the national grid, it may therefore happen that no users can be powered in the event of a grid black-out (unless you have a generator electric of suitable dimensions).

The main purpose of the present invention is to solve the aforementioned drawbacks, providing a control module to be connected both to a plant for the production of electricity from renewable sources and to the 220 V national grid, able to operate autonomously and automatically the choice the most appropriate source of electricity supply (renewable power plant or network), allowing users connected to an electrical system equipped with such a module to be powered by self-produced renewable energy or by the network; in accordance with this purpose, the control module according to the present invention is capable of producing an automatic switching between one or the other power source according to a series of partially programmable conditions and parameters.

The control module of the present invention also has the purpose of managing the use of the energy accumulators forming part of the power plant for the production of energy from renewable sources, maximizing their life cycle.

These and other purposes, as will become clearer from the following description, are achieved by the control module according to the present invention, which is described below, in a preferred, non-limiting embodiment of further developments in the field of the invention, with the help of the attached drawing tables that illustrate the following figures:

fig. 1) the block diagram of an electrical system equipped with the control module; fig. 2) the main elements from which the control module is formed;

fig. 3) the logical operating scheme of the control module;

fig. 4) the electronic circuit of the overload switch;

fig. 5) the electronic circuit of the inverter automatism.

As already mentioned, fig. 1) highlights the placement of the control module (1) between a renewable electricity plant (F) (integral with the photovoltaic panels P, a regulator (S) and batteries (A), all of known technique) and the national grid at 220 V (R); the control module (1) has a logic that always requires the use of the power supply coming from the control unit (F) and, only in the absence of consent consequent to the set parameters, it switches over to the network (R) to allow the energy electricity coming from it, to continue to power the connected users (U).

The first of the parameters that can be set is that of the time bands of potential supply of electricity from the power plant (F); a cyclic timer (T) is connected to module (1) for this purpose.

The programming of the cyclic timer (T), is aimed at using the electricity produced by the plant (F), only in the time slots in which it is assumed that a sufficient quantity of renewable energy is available (for example during the day in case of photovoltaic system), thus avoiding the use of this source when it is known with certainty that it will not be able to supply the users directly (U) because it is scarcely available; by programming the cyclic timer (T), the time band is then established in which the power supply from the control unit can potentially take place (F).

In case of consent from the cyclic timer (T), the control module (1) passes to a second control consisting in checking the state of charge of the batteries (A) in which the renewable energy produced by the plant is stored ( F).

The condition that must be met is that the batteries (A) are fully charged at the time of the first start-up.

The consent from the cyclic timer (T) and the maximum state of charge of the batteries (A), constitute the so-called â € œ starting conditionsâ €.

In the presence of both starting conditions, the control module (1) turns on the inverter (V) connected to it, allowing the control unit (F) to electrically power the utilities (U) connected to the system.

Once the inverter is turned on (V), it remains operational during the entire consent time band set on the cyclic timer (T).

During this time, the batteries (A) act as the flywheel of the plant (F), offsetting the energy demands higher than that produced instant by instant by the plant (F).

In fact, if the power plant (F) produces an amount of electricity equal to or greater than that required by the users (U), it directly feeds the users (U) leaving the batteries (A), already fully charged, in a state of â € œbuoyancyâ €; in the event of energy requests higher than that produced at that moment by the power plant (F), the batteries (A) instead compensate by yielding the amount of supplementary electricity.

During this operational phase, the state of charge of the batteries (A) is therefore subject to continuous variations as, as seen, it lowers when there are peak electricity requests, while it rises again when the power plant (F) produces more electricity than is absorbed by the users (U) connected to the system.

The batteries (A) therefore operate in a charge range that goes from a maximum to a minimum value; both the two values can be set in order to optimize the performance of the batteries (A) and maximize their life cycle.

The maximum value is set by means of a trimmer (15) present in the control module (1), according to the type of batteries used; It is in fact known that depending on the type of batteries (lead, lithium, etc.), the maximum charge value is different.

On the other hand, the minimum value is set with a trimmer (16) and consists in defining the threshold value below which the batteries are not desired (A); by defining this discharge limit (for example by setting the batteries not to go below 40% of the total charge), the harmful complete discharge of the batteries (A) is avoided and their duration and performance are maximized.

When in use the discharge limit threshold set by the trimmer (16) is reached, the control module (1) automatically switches off the inverter (V) followed by the immediate passage to the mains power supply (R) to the purpose of continuing to electrically power the users (U) connected to the system. The batteries (A) therefore continue to supply energy as long as they are in the charge range between the values set using the trimmers (15) and (16).

When the control module (1) selects the network (R) to electrically power the utilities (U) connected to the system, the inverter (V) is switched off thus remaining until the â € œstart conditionsâ € (cyclic timer consent (T) and state of maximum charge of the batteries (A)). Even if the utilities are powered by the network (R), the power plant (F) continues to produce a certain amount of electricity, which is stored in the batteries (A), charging them up to the maximum permitted threshold and thus allowing to meet the â € “starting conditions” of the following day.

The passages from one power source to the other decided by the control module (1) are instantaneous and are operated, as we shall see, by means of a suitable two-phase relay (4).

In the block diagram of fig. 1), the control module (1) is placed between the batteries (A) and the relay (4) which in turn switches between the grid (R) and the inverter (V) which carries the renewable energy produced by the plant (F); the module (1) processes a series of inputs and on the basis of these it energizes or de-energizes an internal relay (3.1) in turn addressed to the external relay (4), allowing the network (R) or the control panel (F) to supply the power supply for the users (U).

Now let's see in detail how the control module (1) is made; from fig. 2) it can be seen that said module (1) is substantially constituted by an electronic circuit called â € œinverter automatismâ € (2) and another one called â € œdisconnector for overloadâ € (3); the two said circuits allow the module (1) to make the choice between the mains power supply (R) or the control unit (F), by commanding the external relay (4) to switch to the power supply coming from one or from the other source.

The inverter automation (2) checks the state of charge of the batteries (A) and is also connected to the cyclic timer (T); if the latter enters the consensus time band, the circuit (2) detects the input and goes on to check whether the batteries (A) are fully charged (aforementioned â € œ starting conditionsâ €).

If the two starting conditions are not both satisfied, the inverter (V) remains off and the power supply for the users continues to be supplied by the grid (R). If, on the other hand, the two starting conditions are both satisfied, circuit (2) sends the inverter start-up signal (V) and energizes the relay (2.1) which enables the following circuit (3) for continuous control of the maximum absorption of connected users.

The overload switch (3) checks the total absorption of the users (U) connected to the system and if it detects that it is higher than the maximum threshold set with a trimmer (17) present on it, it sends a signal to the relay ̈ (3.1) which commands the external relay (4) to make the electricity flow from the grid (R) to power the connected users (U).

If, on the other hand, the total absorption is lower than the value set with the trimmer (17), the relay (3.1) commands the external relay (4) to pass the renewable electricity produced by the plant (F), to supply the utilities (U) connected.

In detail, the power supply for the users (U) connected to the system is preferably supplied by the control unit (F) and its batteries (A); for this reason the relay (3.1) is normally de-energized while the external relay (4) is excited and transits the electrical power supply from the control unit (F).

On the other hand, when the module (1), through its circuits (2) and (3), detects a switch-off requirement of the inverter (V), the relay (3.1) receives an excitation signal and, consequently, the relay External ̈ (4) is de-energized by switching to the mains power supply (R).

Once the inverter (V) is switched on due to the simultaneous presence of the `` starting conditions '', the circuit (2) continuously checks that the charge state of the batteries (A) is included in the operating range between the defined limit values by means of the trimmers (15) and (16) placed inside it; remember that by means of the aforementioned trimmers, the two maximum and minimum battery charge thresholds (A) are set, defining the range within which the batteries must operate following initial start-up.

If the circuit (2) detects that the state of charge of the batteries (A) is lower than the minimum threshold set with the trimmer (16), then it commands the immediate shutdown of the inverter (V) and the consequent disabling of the next circuit. (3).

When the overload cut-out circuit (3) is operational, it continuously monitors the maximum absorption of the connected users; remember that it contains a trimmer (17) through which to set the maximum absorption of the connected users.

If the absorption detected is higher than the limit value set with the trimmer (17), the control on the duration of the demand peak is activated; in fact, it may happen that an electrical requirement exceeding the set limit value lasts a few seconds and coincides, for example, with the starting cues of a household appliance.

In order to prevent this electrical request lasting a few seconds from generating a switching of electrical power supply from (F) to (R), a capacitor (7) in circuit (3) is suitably sized to recognize and tolerate peak electrical demands of the duration of a few seconds.

If, on the other hand, the electrical request has a duration greater than that tolerated by the capacitor (7), the circuit (3) generates a signal that excites the internal relay (3.1) which, consequently, de-energizes the external relay (4) causing a switching that allows the transit of electricity from the grid (R) to power the connected users (U).

We now use fig. 3) to expose some cases that help to understand the logic with which the various elements that make up the control module work (1); those that we will expose are only a part of the numerous eventualities that can occur:

â € ¢ case 1:

I. the cyclic timer (T) does not give consent to the circuit (2)

â – º the electrical power supply of the users is supplied by the mains (R) â € ¢ case 2:

I. the cyclic timer (T) gives consent to the circuit (2)

II. the batteries (A) are fully charged

III. the trimmer (17) is set to a maximum absorption threshold of xx W â – º If the circuit (3) detects that the utilities (U) absorb less than xx W overall, the power supply is guaranteed by the control unit ( F).

â – º If, on the other hand, the circuit (3) detects that the utilities (U) absorb more than xx W overall, the power supply is guaranteed by the network (R).

â € ¢ case 3:

I. the cyclic timer (T) gives consent to the circuit (2)

II. the batteries (A) are not fully charged

â – º Having detected the circuit (2) that the batteries (A) are not fully charged, then the power supply is guaranteed by the mains (R) and the inverter (V) remains off.

Let us now see in detail how the two circuits (2) and (3) are made; the inverter automatism (2) is a monitor of the battery voltage (A) and of the cyclic timer status (T).

As already said, it turns on the inverter (V) when it verifies that the batteries (A) of the system are fully charged and the cyclic timer (T) is in the consent phase; instead it switches off the inverter (V) when the battery is discharged until the residual charge level set with the trimmer (16) is reached, or there is an energy request higher than the limit value set with the trimmer ( 17), lasting longer than that allowed by the capacitor (7).

The battery charge status (A) is monitored by means of two operational amplifiers (5) and (6) which compare the battery voltage with the stabilized voltage present at the output of (8) and suitably adjusted by the two trimmers (15) and (16); the amplifier (5) connected to (15) generates a high logic level signal when the difference between the battery voltage and the reference voltage reaches a value corresponding to "battery charged", while the amplifier (6) connected to ( 16) generates a high logic level signal when the difference between the battery voltage and the reference voltage reaches a value corresponding to "low battery".

The outputs of the two operational units are sent to an S-R type flip-flop circuit, ie to a logic gate which drives the transistor (9); the set impulse activates (9) while the reset impulse deactivates it.

The transistor (9) is connected in series to the transistor (10) and is designed to excite the output relay (2.1); they constitute an "and" gate, ie only if both are activated the output relay (2.1) is activated; (10) in fact receives the base bias voltage from the cyclic timer output (T).

The overload disconnector (3) is instead a monitor of the current flowing on the 220V AC "user line", which energizes or de-energizes the relay (3.1) depending on whether the current on the user line is higher or lower than the preset value by means of the trimmer (17).

The circuit consists of a shunt resistor (11) which, when the disconnector (3) is active, is connected in series to the user line; the voltage across the resistor (11) (proportional to the load of the user) is applied to (12), a voltage step-up transformer necessary to bring the voltage to a value sufficient to polarize the transistor (13).

The output of the transformer (12) is rectified by the diode (14), then filtered and stabilized by the capacitor (7); the latter defines the residence time of the overload situation, after which the relay (3.1) is energized with the consequent de-energization of the external relay (4) and switching of the electricity supply source (from renewable power plant (F ) to net (R)).

This function is critical for the use of the control module (1) as the loads normally present on a consumer are "inductive" and therefore have a high initial inrush current which leads to a shunt inrush voltage (11 ) high; the capacitor (7) must contain this cue in order not to generate transients in the system. The trimmer (17) and the resistors (r1), (r2), (r3) constitute a voltage divider and allow to adjust the bias threshold voltage of the transistor (13); in particular with (17) the threshold of power absorbed by the users (U) is adjusted at which the system must switch over to the network (R).

The polarization of (13) in fact excites the relay (3.1) allowing the users (U) to be powered by the network (R).

Finally, the capacitor (18) filters out any AC disturbances present in the circuit.

Claims (10)

Claims 1) â € œcontrol module and related electronic circuits, for the autonomous and automatic choice of the electricity supply source in a plant connected both to the national grid and to a power station for the production of electricity from renewable sources, as well as for the management of the accumulators of the latter - comprising resistors, transistors, capacitors, relays and transformers belonging to the known art, characterized by an electronic circuit (2) powered by the batteries (A) of a power plant (F) for the production of electricity from renewable sources, for example from the sun by means of photovoltaic panels (P) of a known type, having an input intended for a cyclic timer (T) of a known type as well as an output which, in the presence of certain requirements, can simultaneously power an inverter (V) of a known type and an electronic circuit (3), the latter having an output towards a relay (4) intended to switch between electrical energy coming from the inverter (V) or from the national grid (R), both entering the relay box (4), in order to electrically power the utilities (U) with electricity from renewable sources or from the national grid, the utilities (U) being connected to a system that branches off from the relay (4) and the control unit (F) also integrating a regulator (S). 2) Control module as per claim 1), characterized by the fact that the circuit (2) is responsible for controlling the signals coming from the cyclic timer (T) and detecting the state of charge of the batteries (A), the circuit (2) supplying power to the circuit (3) as well as turning on the inverter (V), only after verifying that the batteries (A) of the control unit (F) are fully charged and the cyclic timer (T) is in the consent phase pre-set by the user, the inverter (V), on the other hand, remains off when the aforementioned conditions are not detected. 3) Control module as per the preceding claims, characterized in that once the inverter (V) is switched on by the circuit (2), it always remains operational until the battery charge (A) is included in the operating range defined by the maximum and minimum values set respectively by trimmers (15) and (16) placed inside said circuit (2), the latter cutting the power supply to the inverter (V) and to circuit (3) when it detects a state of charge of the batteries (A) lower than the value set with the trimmer (16), or when the cyclic timer (T) is no longer in the consent phase. 4) Control module as per the preceding claims, characterized by the fact that the circuit (3) is responsible for monitoring the quantity of electric current flowing on the user line, i.e. the total electricity absorbed by the users (U) connected to the '' electrical system that develops starting from the relay (4), the circuit (3) commanding the relay (4) to switch to the network (R) when it detects a demand for electricity by the users (U) greater than limit value set with another trimmer (17) placed inside said circuit (3), however, given the condition that this demand for electricity lasts longer than that allowed by a capacitor (7) suitably sized to tolerate requests for peak energy lasting a few seconds. 5) Control module as per the preceding claims, characterized by the fact that the relay (3.1) is de-energized and the external relay (4) is energized, whenever the circuit (3) is operational and the users (U) are powered by the electricity produced by the control unit (F), the relay (3.1) being energized instead and commanding the external relay (4) to de-energize when the circuit (3) detects an overload higher than the set limit value with the trimmer (17) and lasting longer than that tolerated by the capacitor (7), the power supply to the users (U) is always supplied by the mains (R) when the external relay (4) is de-energized. 6) Control module as per the preceding claims, characterized by the fact that the functions of the two electronic circuits (2) and (3) can be provided by a single electronic circuit suitably designed to ensure the same functionality of the two said electronic circuits ( 2) and (3), i.e. check the inputs of a cyclic timer (T), check the state of charge of the batteries (A), manage the inverter (V) and monitor the total electricity consumption of the users (U ) connected, then making the same logical choices referred to in the previous claims. 7) Control module as per the preceding claims, characterized by the fact that when the utilities (U) are powered by the control unit (F), the batteries (A) act as the flywheel of the control unit (F) compensating instant by instant the energy requests higher than that produced at that particular moment by the control unit (F). 8) Control module as per the preceding claims, characterized in that the circuit (2) monitors the state of charge of the batteries (A) by means of two operational amplifiers (5) and (6) which compare the battery voltage with the stabilized one present at the output of (8) and suitably adjusted by the two trimmers (15) and (16), the amplifier (5) connected to the trimmer (15) generating a high logic level signal when the difference between the battery and the reference one reaches a value corresponding to "charged battery", the amplifier (6) connected to the trimmer (16) instead generating a high logic level signal when the difference between the battery voltage and the reference voltage reaches a value corresponding to "low battery", the outputs of the two operational units being finally sent to an S-R type flip-flop circuit which drives a transistor (9) connected in series to a transistor (10) designed to excite the r and the output (2.1) of circuit (2). 9) Control module as per the preceding claims, characterized by the fact that the circuit (3) consists of a shunt resistor (11) which is connected in series to the user line so as to detect the voltage at the ends, said voltage being then applied to a voltage step-up transformer (12) necessary to bring the voltage to a value sufficient to polarize a transistor (13), the output of the transformer (12) being rectified by the diode (14) and subsequently filtered and stabilized by the capacitor (7), while the trimmer (17) and the resistors (r1), (r2), (r3) give rise to a voltage divider and allow to adjust the threshold voltage of the transistor (13). 10) Control module as per the preceding claims, characterized by the fact that the polarization of the transistor (13) of the circuit (3) excites the relay (3.1) which de-energizes the external relay (4) which therefore makes the electricity from the network (R) to power the connected users (U), the capacitor (18) finally filtering any AC disturbances present in the circuit.