ITMI20120778A1 - MONITORING SYSTEM FOR A PHOTOVOLTAIC SOLAR SYSTEM - Google Patents

Description

DESCRIPTION

â € œSOLAR SYSTEM MONITORING SYSTEM

PHOTOVOLTAIC â €

FIELD OF APPLICATION

The present invention relates to a monitoring system of a photovoltaic solar plant.

In particular, the present invention relates to a monitoring system of a photovoltaic solar plant aimed at contrasting the frequent attempts to steal the panels of the plant.

The system of the invention is mainly applied to counter theft of photovoltaic solar panels, especially during the night and mainly in large plants positioned on the ground, but also to detect faults and malfunctions.

TECHNIQUE NOTE

To date, the protection of panels in photovoltaic systems from theft can be achieved with various techniques, for example by using conventional protection and alarm systems, such as fences and perimeter IR barriers, seismic sensors, video surveillance, tamper-proof fixing elements, etc., or by using anti-theft systems. dedicated, for example to optical fibers.

These systems are expensive and complex as they represent real autonomous systems dedicated to protection and require additional equipment and wiring that increase installation and maintenance costs; in addition, some passive components (eg tamper-proof fastening elements) can preclude or complicate maintenance interventions on the system.

Other rarer systems are made with dedicated components which are able to disable themselves if the system is not correctly installed.

These systems are also expensive and complex and, in addition, they severely limit the flexibility of installation and supply of components of the entire system, as they are linked to a specific model of panels or inverters.

Other systems of different conception are integrated into the photovoltaic solar system and use the conductors already present in the system itself.

The main disadvantage of these systems is the strong limitation in the type of detectable tampering, which makes their use unreliable.

The purpose of the present invention is to provide a monitoring system for a solar photovoltaic system that is reliable in detecting any type of tampering and / or malfunction.

The particular purpose of the invention is to provide a monitoring system for a solar photovoltaic system that is efficient in detecting theft of panels from the system itself.

A further purpose of the invention is to provide a monitoring system for a solar photovoltaic system which guarantees continuous and constant monitoring of the system panels.

SUMMARY OF THE INVENTION

These and other purposes are achieved by a monitoring system of a photovoltaic solar plant, according to what is described in claims 1 to 8.

These and other purposes are also achieved by a photovoltaic solar system comprising a photovoltaic solar plant and a system for its monitoring, as described in claims 9 to 11.

The invention, as described, has the following technical effects:

â € ¢ allows reliable detection of the presence or absence of solar panels with respect to predefined conditions;

â € ¢ it allows constant day and night monitoring of a solar photovoltaic electricity production plant;

â € ¢ It can be installed for all types of systems, regardless of both the brand of the panels and the brand of the inverters to which the system is connected.

â € ¢ gives information on the status of the electricity network to which the system is connected;

â € ¢ it gives indications on the production deficit of the plant not attributable to the absence of components but to their malfunction.

The cited technical effects and other technical effects of the invention will result in more detail from the description, given below, of an example of embodiment given by way of indication and not of limitation with reference to the attached drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

Figure 1 shows a block diagram of a monitoring system of a solar photovoltaic plant and of the corresponding monitored solar photovoltaic plant, according to the invention.

Figure 2 shows a detailed block diagram of the monitoring system only, according to the invention. Figure 3 shows a circuit diagram of a string of photovoltaic panels of the plant in figure 1.

Fig. 4 shows a particular circuit of a component of the monitoring system.

DETAILED DESCRIPTION

The invention describes a monitoring system of a photovoltaic solar plant equipped with at least one string of photovoltaic panels.

With reference to Figure 1, two strings 1, 2 are shown comprising respective panels 10, 11 and 20, 21.

In general, each string 1,2 can include at least one photovoltaic panel in which a Dbp recirculation diode is associated with each panel.

In the example of realization shown, two strings 1,2 of photovoltaic panels will be considered. In the following, for simplicity, the strings of photovoltaic panels will be briefly defined as "strings" and the terms "panels" and "modules" will be used as synonyms.

According to the invention, each panel 10, 11, 20, 21 is associated with a recirculation diode (bypass diode) Dbp arranged in parallel to the panel itself; as is known, the recirculation diode allows a passage of charges between successive panels when the panel associated with the recirculation diode is not working.

The solar photovoltaic system also includes inverters 12,22 connected downstream of the respective strings 1,2.

With reference to Figures 1 and 2, the monitoring system of the invention comprises at least one primary control device 15.25 configured for monitoring the strings 1,2 of photovoltaic panels 10,11,20,21.

The primary control device 15.25 is interposed between the inverter 12.22 and strings 1.2.

Still with reference to Figures 1 and 2, the monitoring system of the invention comprises a master control device 50, in data connection with the at least one primary control device 15, 25.

The master control device 50 is configured to receive data representative of a state Si of the string 1,2 of the photovoltaic panels 10,11,20,21 from the at least one primary control device 15. Thanks to the presence of the recirculation diodes in parallel to the photovoltaic panels, and through a signal measurement downstream of the photovoltaic strings, it is possible to determine states of tampering of the string.

In particular, knowing the amplitude of the signal sent to the string, the following states can be determined:

S1: open circuit, as no signal will be measured downstream of the string;

S2: complete short circuit, as the downstream signal will be measured identical to the one sent;

S3: partial short circuit, that is the absence of some panels, as the amplitude of the signal will not correspond to the drop on the entire string.

For determining the Si state of the string, the primary control device 15.25 comprises a current pulse generator, hereinafter described as a pulse generation module 40, and a certain number of sensing circuits, one for each monitored string, included in a sensing module 33, (described below) for detecting the signal downstream of the string.

More precisely, the primary controller 15.25 includes a processing unit 30.

In general, it should be noted that in the present context and in the subsequent claims, the processing unit 30 and, in general, all the processing units, are presented as divided into distinct functional modules (memory modules or operating modules) for the sole purpose of clearly and completely describe the functionality of the units themselves.

In reality, these units can consist of a single electronic device, suitably programmed to perform the described functions, and the various modules can correspond to hardware entities and / or software routines forming part of the programmed device.

Alternatively or in addition, these functions can be performed by a plurality of electronic devices on which the aforementioned functional modules can be distributed.

The processing units can also use one or more processors to execute the instructions contained in the memory modules.

The aforementioned functional modules can also be distributed on different computers locally or remotely based on the architecture of the network in which they reside.

Advantageously, according to the invention, the primary control device 15.25 checks at regular intervals (or alternatively receives at regular intervals) the presence of the strings connected to the inverter and through the modules included in the processing unit 30, in particular the pulse generation module 40 and the sensing module 33 determine and update the status Si of the strings.

The pulse generation module 40 is configured to generate a train of pulses Ii to be sent towards the strings 1,2 of photovoltaic panels to verify the presence and continuity of the connection.

Advantageously, according to the invention, to generate the pulse train Ii, the pulse generation module 40 comprises a suitably controlled DC-DC converter and a high frequency transformer. The DC-DC converter used is in half-bridge configuration. (fig. 4)

Among the possible DC-DC converters that can be used, the half-bridge architecture is suitable for the purpose, simple to implement and with low costs.

As previously mentioned, the operation of the monitoring system foresees the presence of the recirculation diodes present on the photovoltaic panels: by sending, through the pulse generation module 40, the train of pulses Ii on the negative pole of the strings, it is monitored, through photo-couplers, included in the sensing modules 33, if the pulses cross the string, in order to verify the presence and continuity of the connection.

By controlling the half bridge with a PWM modulation it is possible to obtain a train of pulses of suitable amplitude with a duty cycle of 50%.

This type of system allows you to detect three types of tampering, corresponding to the Si states of the system mentioned above:

â € ¢ S1: opening of the electrical circuit: in the event of disconnection of one or more strings, the pulse train will not be detected by the respective sensing circuit.

â € ¢ S2: total replacement with a short circuit; in case of bypass of the whole string with a short circuit the load will be unbalanced and the shorted string will have an anomalous current absorption while on the other strings the absorption will decrease to practically zero. In this way the pulse train will be detected only on the tampered strings.

â € ¢ S3: partial removal with a short circuit; It is a case similar to the previous one, with the difference that not all the string is bypassed but only a portion. Also in this case the load is unbalanced towards the string with fewer panels connected and therefore the current absorption is predominant on the tampered string.

The system also allows you to detect a state

â € ¢ S4: regular operation within the preset thresholds

As already mentioned, according to the invention, the processing unit 30 comprises a sensing module 33 (fig 2) configured to detect parameters Ps representative of the presence of the strings 1,2 of photovoltaic panels.

According to the invention, the sensing module 33 is configured to detect parameters Ps representative of the presence of the strings 1,2 of photovoltaic panels 10,11,20,21 as a function of the pulses Ii sent by the pulse generation module 40.

These representative parameters can be electrical parameters such as, for example, voltage, current, frequency, impedance detected by the sensing module in the particular conditions.

According to the invention, the sensing module 33 has a linear response.

The sensing module 33 includes one or more of:

linear opto-couplers;

resistive shunts;

Hall effect probes;

or similar

Preferably, the sensing module is formed by various branches, each of which is connected to the positive terminal of a photovoltaic string.

The train of pulses sent to the negative terminal of the strings, connected in parallel, crosses them using the by-pass diodes on each panel and closes on the sensing branch.

The signal that is detected through a linear optocoupler contains the representative information Ps of the presence of the photovoltaic string, as the amplitude of the pulses is determined by the voltage drop on the diodes encountered.

The main part of the circuit is formed by the linear sensing circuit and the sensing resistor which determines the current circulating on the branch.

This point is very important as the sensing circuit saturates for currents above a predefined current threshold.

On the sensing branch there are also safety devices (eg zener diodes) placed in parallel to the sensing circuit in order to prevent high input voltages from damaging the sensing circuit.

There is also a high voltage capacitor to prevent the DC component from ending up on the transformer secondaries, risking damaging it.

Advantageously, according to the invention, the processing unit 30 comprises a configuration module 31 (fig. 1 and 2) configured to detect the number of the strings 1,2 of photovoltaic panels connected to the respective inverters 12,22.

In this way, the configuration module 31 determines a first reference threshold I for recognizing the state Si of the strings.

This detection is peculiar to a daytime control in which the system is off as it is not necessary to signal the presence of the panels and it is sufficient to check the energy production and the information sent by the inverter.

However, the monitoring device is always connected to the photovoltaic strings even during the day, so the device must be able to tolerate even high input voltage values without being damaged.

For this reason, Zener diodes have been placed in order to limit the input voltage to the optolinear. In this way, the opto-linear will always detect the maximum value and this information can be used to verify the presence or absence of the string even during the day.

To summarize, therefore, in daytime mode, the system detects:

- correct functioning;

- opening of the circuit of a string of photovoltaic panels;

- short circuit of a string of panels by means of a bridge at the beginning of the string in an attempt to exclude the panels;

The configuration module 31 is also configured to determine a threshold value for the presence of the strings 1,2 of photovoltaic panels.

In particular, the configuration module 31 is configured to determine a reading value of the sensing module corresponding to a threshold of presence of the strings 1,2 of photovoltaic panels. In other words, the threshold determined by is also detected

- a partial short circuit of a string, by means of a half-string bridge in an attempt to exclude only some panels of the string.

The configuration module 31 therefore determines a second reference threshold II for recognizing the state Si of the string.

This detection is peculiar to a night check. The technical effect of the day and night operating configurations is the continuous and constant monitoring of the Si state of the string 1,2 of photovoltaic panels 10,11,20,21.

As a result, the detection gives very reliable results.

According to the invention, the processing unit 30 further comprises a comparison module 32 configured to compare the representative parameters Ps with the reference thresholds I; II, to recognize a possible state Si of the string, which corresponds to one of the above states described.

According to the invention, the primary control device 15.25 comprises a communication module 34 configured to communicate to the master control device 50 the status Si detected by the comparison module 32.

For this purpose, the master control device 50 comprises a first auxiliary communication module 51 configured for communication with at least one primary control device 15.25.

The master control device 50 further comprises a second auxiliary communication module 52 configured for a communication with a network module 61 configured for a transmission of data, for example the status Yes, to remote users.

More specifically, a wireless module or an RS485 module is preferably used as the first auxiliary communication module 51, while a TCP / IP module is preferably used as the second auxiliary communication module 52.

Inside the master control device 50, a control unit may be provided that deals with the interfacing between the communication devices in the event of some problems relating to communication compatibility.

The invention also describes a photovoltaic solar system comprising a photovoltaic solar plant monitored by a monitoring system. The solar photovoltaic system includes at least one string 1,2 of photovoltaic panels 10,11,20,21, in which each panel includes a Dbp recirculation diode, the system also including an inverter 12,22 connected downstream of the string 1.2. Advantageously, according to the invention, the photovoltaic solar system comprises a monitoring system of the photovoltaic solar plant, with the characteristics described above.

According to the invention, the photovoltaic solar plant further comprises a monitoring cabin 60 (Fig. 1).

The monitoring system comprises a network module 61, associated with the monitoring cabin 60, configured for a transmission of the status Si of the strings to a remote user.

Claims (11)

CLAIMS 1. Monitoring system of a solar photovoltaic system in which said system includes: â € ¢ at least one string (1,2) of photovoltaic panels (10,11,20,21) in which a recirculation diode (Dbp) is associated with each panel; â € ¢ an inverter (12,22) positioned downstream of said at least one string (1,2); in which the monitoring system includes â € ¢ at least one primary control device (15.25) configured for monitoring of said at least one string (1,2) of photovoltaic panels (10,11,20,21), said primary control device (15,25 ) being interposed between said inverter (12,22) and said at least one string (1,2) of photovoltaic panels (10,11,20,21); â € ¢ a master control device (50), in data connection with the at least one primary control device (15, 25), configured to receive representative data from said at least one primary control device (15, 25) of a state (Si) of said at least one string (1,2) of said photovoltaic panels (10,11,20,21); wherein said primary control device (15.25) comprises a processing unit (30) comprising, in turn: or a configuration module (31) configured for: detect the number of said strings (1,2) of photovoltaic panels (10,11,20,21) connected to said inverter (12,22), thereby determining a first reference threshold (I) for the recognition of said state (Yes), and / or determining a presence threshold of said strings (1,2) of said photovoltaic panels (10,11,20,21), thereby determining a second reference threshold (II) for the recognition of said state (Si); or a sensing module (33) configured to detect representative parameters (Ps) of the presence of said strings (10,11,20,21) of photovoltaic panels; or a comparison module (32) configured to compare said representative parameters (Ps) with said reference thresholds (I; II), to detect said state (Si). System according to claim 1 wherein said primary control device (15.25) comprises a communication module (34) configured to communicate to said master control device (50) said state (Si) as a function of said comparison made from said comparison module (32). System according to any one of claims 1 or 2 wherein said processing unit (30) comprises a pulse generation module (40) configured to generate a train of pulses (Ii) to be sent towards said strings (1 , 2) photovoltaic panels to verify the presence and continuity of the connection. 4. System according to claim 4 wherein said pulse generation module (40) comprises a controlled DC-DC converter and a high frequency transformer. 5. System according to any one of the preceding claims, in which said sensing module (33) is configured to detect said representative parameters (Ps) of the presence of the strings (1,2) of photovoltaic panels (10,11,20,21) as a function of said pulses (Ii) sent to said strings by said pulse generation module (40). 6. System according to claim 5 wherein said sensing module (33) is linear response. System according to claim 5 or 6 wherein said sensing module (33) comprises one or more of: linear opto-couplers; resistive shunts; effect probes o or similar System according to any one of the preceding claims, wherein said master control device (50) comprises one or more of: â € ¢ a first auxiliary communication module (51) configured for communication with said at least one primary control device (15.25); â € ¢ a second auxiliary communication module (52) configured for communication with said network module (61); 9. Solar photovoltaic system comprising: â € ¢ a photovoltaic solar system comprising: or at least one string (1,2) of photovoltaic panels (10,11,20,21) in which a recirculation diode (Dbp) is associated with each panel; or an inverter (12,22) positioned downstream of said at least one string (1,2); characterized by the fact of understanding: â € ¢ a monitoring system of said solar photovoltaic system comprising: or at least one primary control device (15.25) configured for monitoring of said at least one string (1,2) of photovoltaic panels (10,11,20,21), said primary control device (15.25) being interposed between said inverter (12,22) and said at least one string (1,2) of photovoltaic panels (10,11,20,21); â € ¢ a master control device (50), in data connection with the at least one primary control device (15, 25), configured to receive representative data from said at least one primary control device (15, 25) of a state (Si) of said at least one string (1,2) of said photovoltaic panels (10,11,20,21); wherein said primary control device (15.25) comprises a processing unit (30) comprising, in turn: or a configuration module (31) configured for: detect the number of said strings (1,2) of photovoltaic panels (10,11,20,21) connected to said inverter (12,22), thereby determining a first reference threshold (I) for the recognition of said state (Yes), and / or determining a presence threshold of said strings (1,2) of photovoltaic panels (10,11,20,21), thereby determining a second reference threshold (II) for the recognition of said state (Si); or a sensing module (33) configured to detect representative parameters (Ps) of the presence of said strings (1,2) of photovoltaic panels (10,11,20,21); or a comparison module (32) configured to compare said representative parameters (Ps) with said reference thresholds (I; II), to detect said state (Si). Photovoltaic solar system according to claim 9 wherein said photovoltaic solar system comprises a monitoring cabin (60). 11. Photovoltaic solar system according to claims 9 and 10 wherein said monitoring system comprises a network module (61) configured for a transmission of said state (Si) to a remote user, said network module (61) being associated with said monitoring cabin (60).