Method for evaluating photovoltaic power generation and evaluation and management unit implementing the method

Abstract

The invention relates to a photovoltaic power production evaluation method for evaluating the photovoltaic power production of an energy supply installation (11) installed on a site (1), said energy supply installation (11) comprising at least one power production unit (12) comprising at least one photovoltaic module (14); characterized in that it comprises the following steps: - determining past or predictive irradiance values of the site (1) on which the energy supply installation (11) is installed, this determination being made over a time interval of one second to two years, and - evaluating the photovoltaic electric power produced as a function of the determined irradiance values and of values previously recorded in a database (30) comprising previously recorded values for each day of the year and for different time instants of each day, which make it possible to determine the photovoltaic electric power produced as a function of the irradiance.

Description

TECHNICAL FIELD

[0001] The present invention relates to the field of photovoltaic power production evaluation. More specifically, the present invention relates to a method for evaluating photovoltaic power production and an evaluation and management unit implementing the method. BACKGROUND

[0002] Due to the increasing cost of fossil energy and the increasing pollution resulting from the consumption of these fossil energies, there is a growing interest in renewable energies and in energy consumption according to a logic of sustainable development. This trend naturally favors renewable energies such as solar energy. The current practice is to install photovoltaic panels, in particular on the roofs of commercial, public buildings, or simply on the roofs of private homes, for self-consumption or to supply the public grid with, for example, all the production or only the excess energy.

[0003] Positive energy districts are currently being developed. These districts aim at being self-sufficient in terms of electricity by producing in a renewable way the energy they consume. An example of such a district is the IssyGrid project, which is an experimental project combining private homes and offices. For this project, different sites have been particularly equipped with photovoltaic modules to be able to produce electricity to meet the energy needs of the facilities of the district.

[0004] The different electrical devices of these facilities are for example interconnected in a network and can also be controlled to optimize their operation according to the instantaneous production and / or the storage in, for example, accumulators, while limiting the backup power from the public grid to which the district is connected.

[0005] There are also different control modules that allow limiting the consumption of different electrical devices to control the optimized operation of, in particular, air conditioning or heating (reversible heat pump) facilities, household appliances (washing machine, dishwasher, water heater) or even lighting.

[0006] Thus, the IssyGrid project aims at creating a district that is able to produce the energy it needs and possibly to inject the excess renewable electricity into the public grid.

[0007] To achieve at least partially such autonomy, it must be possible to evaluate the photovoltaic electrical energy produced in a predictable way, which makes it possible to choose between, on the one hand, using backup power from the public grid or from storage in accumulators and, on the other hand, simply turning off some consumers considered, for example, non-critical, in the event of a high energy demand and insufficient renewable production.

[0008] In fact, if the amount of renewable energy available or produced is either in excess or insufficient to meet the energy demand of the various consumers in the area, it can be necessary to implement storage solutions, to inform the operator of the public grid or to take from the storage units, or to limit certain identified consumers.

[0009] Such a solution can occur, for example, in the case of a harsh winter, during which the power generation capacity of renewable energy is significantly lower than the demand, or, conversely, in the summer when the photovoltaic power production is high and the daytime consumption is low.

[0010] In the case of photovoltaic plant design, some software is currently known which allows to calculate the renewable power production forecast. For a certain power site in the future, the software is used to determine the size of the photovoltaic plant and generally takes into account historical meteorological data.

[0011] These historical meteorological data include, for example, the level of light in different periods of the year in the geographical area where the plant is to be set up.

[0012] The software is mainly developed to calculate the return on investment of such a project and the financial viability thereof.

[0013] In a more complex version for self-consumption projects, some software also takes into account the power demand and the consumer side of a more complex plant comprising a power production unit, a power storage unit and a power consumption unit.

[0014] However, this type of software cannot predict the photovoltaic power produced by the power production unit in a future period, especially day by day and with a sampling interval sufficiently precise, in a reliable or practical way. Indeed, the photovoltaic power produced by the power production unit depends on the immediate meteorological conditions. These meteorological conditions can vary from one day to another or even within the same day.

[0015] Moreover, the calculations made by this software are quite complex and time-consuming, which makes it unsuitable for making predictive assessments to allow, for example, real-time adjustment of the power supply or consumption of electrical equipment.

[0016] Moreover, these known photovoltaic simulation software were initially designed to assess annual performance, they often have a calculation interval of about one hour and cannot be adjusted, which is too long for same-day assessment requiring minute-level assessment predictions.

[0017] Therefore, these software, although very good in terms of modeling and ergonomics, are not suitable for predicting photovoltaic power in the short term, are not accurate and require a large amount of calculation time.

[0018] Therefore, in order to meet the energy needs of the different facilities of these positive energy neighborhoods, it is necessary to be able to predict in real time the photovoltaic electrical power produced and possibly to activate the supply or injection of electricity from the public grid to these facilities, to activate storage units or to command a reduction of the consumption or the switching on of certain identified electrical consumers or electrical equipment in the neighborhood.

[0019] In hybrid electrical systems, especially with thermal power generators such as diesel generators, short-term photovoltaic predictions allow to anticipate a decrease in solar power production, for example due to the passage of clouds, and to switch on one or more generators in advance, to allow to avoid forced shutdowns or even blackouts. In return, reliable predictions allow to minimize the number of engines in operation, reducing fuel consumption and maintenance needs, while ensuring reliable power supply.

[0020] It is therefore one of the objectives of the present invention to provide a solution to allow to evaluate photovoltaic power production in real time without using complex calculations.

[0021] Another aspect relates to controlling the electrical power produced for diagnostic purposes. Indeed, by evaluating in a sufficiently precise manner the theoretical photovoltaic power production of the power production unit over a past time interval according to the actual meteorological conditions and comparing this theoretical power production with the actual power production of the power production unit over the same time interval, it is possible to determine the operating state of the power production unit and, in the event of too large a deviation, to schedule for example a necessary maintenance operation.

[0022] Indeed, if the electrical power produced is too much less than the expected electrical power, it can be deduced that the power production unit has a technical fault, for example a module chain or inverter fault, or a dust or mud deposit, etc.

[0023] It is therefore an objective of the present invention to at least partially overcome the above-mentioned problems of the prior art by proposing a simple method of evaluating photovoltaic power production allowing to monitor, diagnose or predict the photovoltaic power production. SUMMARY

[0024] To this end, the subject of the present invention is an evaluation method of photovoltaic power production of an energy supply facility installed on a site, said energy supply facility comprising at least one power production unit having at least one photovoltaic module;

[0025] The photovoltaic power production evaluation method comprises the following steps:

[0026] - determining past or predictive irradiance values of the site on which the energy supply facility is installed, this determination being made over a time interval of one second to two years, and

[0027] - evaluating the photovoltaic electric power produced according to the determined irradiance value and to values pre-recorded in a database comprising pre-recorded values for each day of the year and for different time instants of each day enabling to determine the photovoltaic electric power produced according to the irradiance.

[0028] The different steps of the method are for example automatically performed by an evaluation and management unit comprising processing means, or a computer system such as a microprocessor or a microcontroller. As will be described hereafter in the present description, the capabilities of these processing means can be limited due to the use of a database. In particular, the photovoltaic electric power produced values are read by the processing means and can be subsequently stored and processed.

[0029] The use of a database, for example in the form of a table, to determine the photovoltaic electric power produced by the power generation unit by introducing the irradiance, limits the computing power required for determining this produced photovoltaic electric power.

[0030] Thus, the use of such a database facilitates the computation and thus allows a simpler and faster determination of the photovoltaic electric power produced at any time instant of the day. Moreover, the use of such a database allows an automated determination of the photovoltaic electric power produced by the power generation unit.

[0031] The present application can also comprise one or more of the following aspects, alone or in combination:

[0032] According to one aspect, the values pre-recorded in the database correspond to photovoltaic electric power values produced according to irradiance values.

[0033] The database comprises for example for each time instant comprised in the database, electric power values produced according to different irradiance levels ranging from 0 to 1300 W / m 2 , in increments of 10 W / m 2 .

[0034] For an irradiance level not given in the database, but located between two levels given in the database, the photovoltaic electric power value can be determined by linear interpolation of the photovoltaic electric power values indicated for the two irradiance levels given in the database.

[0035] According to another aspect, the values pre-recorded in the database correspond to coefficients of a mathematical function describing the electric power values produced according to the irradiance.

[0036] The mathematical function can be a polynomial, in particular a fourth degree polynomial.

[0037] The coefficients of the mathematical function are determined in particular by performing a least squares regression on the generated electrical power values as a function of the irradiance values, the range of which is for example 0 to 1300 W / m 2 .

[0038] The method can comprise a step of correcting the photovoltaic electrical power generated as a function of the irradiance by taking into account the predicted, past or measured temperature and / or wind speed values on the installation site by applying a correction coefficient.

[0039] In particular, the correction coefficient is a linear correction coefficient.

[0040] The pre-recorded values are given in the database for example at least between sunrise and sunset each day, the time interval between these diurnal instants being between 5 minutes and 2 hours, in particular 1 hour.

[0041] For a diurnal instant not given in the database, but situated between two instants given in the database, the pre-recorded value thereof can be determined by linear interpolation of the pre-recorded values indicated by the two instants given in the database.

[0042] In particular, the sampling interval for which the electrical power production is evaluated is less than or equal to five minutes, in particular one second.

[0043] The application also relates to a method for predicting photovoltaic electrical power production and managing electrical equipment for an energy supply installation, the site on which the energy supply installation is installed being equipped with at least one electrical equipment, the energy supply installation comprising at least one electrical power production unit comprising at least one photovoltaic module, the method comprising the following steps:

[0044] - performing the photovoltaic electrical power production evaluation method as described above, in which, in the step of determining the irradiance values, predictive irradiance values are determined for the site on which the energy supply installation is installed, the determination being performed over a predictive time interval of between one second and two days, and

[0045] - adjusting the operating mode of at least one electrical equipment as a function of the evaluation of the photovoltaic electrical power production of the energy supply installation.

[0046] The application also relates to a method for monitoring and diagnosing the photovoltaic electrical power production of an energy supply installation installed on a site, the energy supply installation comprising at least one electrical power production unit comprising at least one photovoltaic module, the method comprising the following steps:

[0047] - performing the photovoltaic electrical power production evaluation method as described above, in which, in the step of determining the irradiance values, historical irradiance values are determined for the site on which the energy supply installation is installed for a past time interval, and

[0048] - comparing the evaluated photovoltaic power generation with the photovoltaic power generation measured in the past time interval.

[0049] According to an additional aspect, the method further comprises the step of generating an alert, if the difference between the evaluated photovoltaic power generation and the photovoltaic power generation measured in the past time interval exceeds a predetermined threshold.

[0050] The present application also relates to an evaluation and management unit comprising means configured to implement the method as described above.

[0051] The present application also relates to a computer program product, loadable into the internal memory of an evaluation and management unit comprising portions of software code for executing the steps of the method as described above when said computer program is executed by a computer. BRIEF DESCRIPTION OF DRAWINGS

[0052] Other characteristics and advantages of the present application will appear in the following description, made with reference to the attached drawings provided as non-limiting examples, in which:

[0053] Figure 1 is a schematic perspective view of a site equipped with energy supply facilities from renewable sources;

[0054] Figure 2 is a schematic overview of a local power grid comprising the energy supply facilities;

[0055] Figure 3 is an example of a schematic excerpt of a database evaluating photovoltaic electric power, as a function of the irradiance level and the time of the year, evaluating the photovoltaic electric power produced by the energy supply facilities on the site in Figure 1 and 2 ;

[0056] Figure 4 is an example graph showing, for a plurality of time instants of the year, the photovoltaic electric power produced by the energy supply facilities on the site in Figure 1 and 2 , as a function of the irradiance;

[0057] Figure 5 is an example of a schematic excerpt of a database evaluating photovoltaic electric power, as a function of the irradiance and the time of the year, evaluating the photovoltaic electric power produced by the energy supply facilities on the site in Figure 1 and 2 , with coefficients of a polynomial function;

[0058] Figure 6 is a graph showing the composition of a database for evaluating the photovoltaic electric power produced by the energy supply facilities on the site in Figure 1 ;

[0059] Figure 7 is a flowchart of an embodiment of a method for evaluating the photovoltaic electrical power produced;

[0060] Figure 8 is a flowchart of an embodiment of a method for predicting photovoltaic electricity production and managing electrical equipment; and

[0061] Figure 9 is a flowchart of an embodiment of a method for monitoring and diagnosing photovoltaic electricity production. DETAILED DESCRIPTION

[0062] In all the figures, elements having the same functionality have the same reference signs.

[0063] The following examples are illustrative. Although the present specification can refer to one or more embodiments, it is not necessarily implying that each reference is to the same embodiment or that each feature only applies to a single embodiment. Single features of different embodiments can also be combined to provide other embodiments.

[0064] Definitions

[0065] In the following description, a "photovoltaic module" refers to the most basic (direct current) electricity production unit, which is composed of photovoltaic cell assemblies connected to each other and completely protected from the external environment, i.e. as defined by the IEC-TS 61836 standard.

[0066] In the following description, "real time" refers to an evaluation sampling interval less than or equal to ten minutes, in particular less than or equal to five minutes, in particular every minute.

[0067] In the following description, "irradiance" or energy irradiance (French éclairement énergétique) according to the ISO 80000-7 § 19 standard refers to the quantification of the power of electromagnetic radiation impinging on a unit of area. The irradiance corresponds to the surface density of the energy flow reaching the considered point on a surface. For the entire solar spectrum or a limited part of the spectrum, this surface density is expressed in watts per square meter (W / m2). The irradiance can be in particular the "Global Horizontal Irradiance" (English GHI), the irradiance in a fixed or variable defined plane such as the module plane, the diffuse irradiance and / or the normal direct irradiance or a combination of the above information. 2

[0068] In French, the word "temps" can be associated with the chronology or the weather. In the present specification, the word "temps" will be used only to describe the time element, the words "weather" or "meteorological" being used to describe elements associated with the weather. ​

[0069] "meteorological parameter" means any meteorological parameter that can influence the operation of the photovoltaic module, in particular its efficiency, such as the irradiance value, the temperature and / or the wind speed on the installation site.

[0070] "temporal interval" means the duration between the beginning and the end of an evaluation period or a prediction period. The predictive temporal interval is the duration between the future prediction time and the current time. If the predictive temporal interval is 36 hours, it means that the meteorological parameter values can be predicted at the current time for 36 hours from now.

[0071] "sample interval" means the duration between two times, for example necessary to determine the irradiance value, or the duration between photovoltaic power evaluation points on the "temporal interval". Thus, for a predictive temporal interval of 36 hours and a sample interval of 5 minutes, the photovoltaic power can be calculated every 5 minutes for 36 hours from now, which gives 36 x 60 / 5 + 1 = 433 future power values.

[0072] Site

[0073] Figure 1 A site 1, for example a commercial site, for example a service station with a retail building 3 and a fuel filling building structure 5, the building structure 5 having a roof 7, for example of the awning type, is shown. Various electrical equipment 10 is also installed on the site 1.

[0074] The electrical equipment 10 is, for example, a heat pump, an air conditioning system, lighting and / or display equipment, a fuel filling pump, or even an automatic filler.

[0075] A power supply installation 11 (see Figure 2 ) is also installed on the site 1, comprising at least one power generation unit 12 having at least one, preferably a plurality of photovoltaic modules 14, and an evaluation and management unit 16.

[0076] Each photovoltaic module 14 of the power generation unit 12 has known power generation characteristics, in particular of the electric power generated as a function of the insolation, more particularly as a function of the irradiance, and for example of the temperature. Photovoltaic modules 14 of known technology can be used, for example modules having, for example, crystalline silicon photovoltaic cells (not shown).

[0077] As can be seen in Figure 1 , the photovoltaic modules 14 are, for example, installed on the roof 7 of the fuel filling building structure 5.

[0078] The power supply installation 11 can also optionally comprise an electrical energy storage unit 18 for storing the electrical energy generated by the power generation unit 12 and / or the thermoelectric generator 20.

[0079] The storage unit 18 can be, for example, a battery or an electrical energy accumulator.

[0080] The thermoelectric generator 20 can be formed by a diesel generator set which can be switched on, for example in case of a failure or outage of the public grid, or in case it is economically more advantageous to take electricity from the public grid than to start the engine set, to guarantee the supply of electricity.

[0081] Obviously, other embodiments are contemplated in which the site 1 can be a residential and / or industrial park comprising individual or collective housing, offices or even industrial buildings.

[0082] As schematically shown in Figure 2 the power supply facility 11 and the electrical equipment 10 are interconnected, for example in a local grid 22 controlled by the evaluation and management unit 16.

[0083] As will be explained in greater detail hereinafter, the evaluation and management unit 16 is configured to analyze the electricity production of the electricity production unit 12, to analyze the electricity requirements of the electrical equipment 10, and to control the electricity flow between, for example, the storage unit 18 and / or the individual units of the one or more thermoelectric generators 20 and the local grid 22. The local grid 22 is further connected to a public grid 24 which can receive the excess electricity produced by the power supply facility 11 or allow to complement the supply, completely or partially, or to replace the electricity production unit 12, as appropriate.

[0084] To this end, the evaluation and management unit 16 is configured, for example, to activate / disable / control switches, relays and / or converters (not shown) provided in the local grid 22 and to manage the various electric currents.

[0085] Thus, depending on what is most economically advantageous, for example, for the operator of the site 1, the electricity produced by the electricity production unit 12 can be consumed directly by the electrical equipment 10, stored by the storage unit 18, or supplied to the public grid 24.

[0086] The electricity stored by the storage unit 18 can be supplied, for example, to the electrical equipment 10, in particular in case of insufficient electricity produced by the electricity production unit 12.

[0087] The electricity of the public grid 24 can be supplied, for example, to the electrical equipment 10, in particular in case of insufficient electricity produced by the electricity production unit 12 and / or the thermoelectric generator 20, or in case of insufficient available electricity in the storage unit 18.

[0088] Finally, the electricity produced by the local thermoelectric generator 20, for example a diesel generator set, can also be switched on, for example in case of a failure or outage of the public grid 24, to ensure that backup power can be supplied to the electrical equipment 10.

[0089] Therefore, in order to enable the evaluation and management unit 16 to make these judgments, it is necessary to predict in real time the photovoltaic electricity production achieved by the electricity production unit 12, which depends highly on the meteorological conditions on the site 1, and also to take into account the electricity requirements of the various electrical devices 10 and the conditions for buying back or selling electricity to the public electricity network 24.

[0090] In a more advanced variant, the evaluation and management unit 16 is configured to control the energy consumption of at least some of the electrical devices 10 more finely, for example to limit the consumption of some of the electrical devices 10 over a given period. In particular, by limiting the consumption on the public electricity network 24, this increases the energy autonomy of the site 1 and thus optimizes the electricity bill of the site 1. In the case of an air conditioning system for example, the evaluation and management unit 16 can be configured to increase the target temperature by one degree for example to limit the consumption.

[0091] In order to inform the operator of the public electricity network 24 in order to be authorized to take a certain amount of electricity from the public electricity network 24 without penalty or to inject a certain amount of electricity into the public electricity network 24, or simply to be able to start the thermal power generator 20 in time, the predictive aspect can also be necessary.

[0092] To this end, in particular, the evaluation and management unit 16 is connected, in particular via the remote communication means 26, to a meteorological evaluation system 28 configured to communicate to the evaluation and management unit 16 predictive or historical meteorological parameters, for example the irradiance values, the wind speed or the temperature at the site 1 on which the electricity production unit 12 is installed. The meteorological evaluation system 28 is remote and comprises for example a remote server.

[0093] The evaluation and management unit 16 is for example a computer equipped with a memory, one or more processors or microcontrollers and communication means configured to communicate and control the energy supply installation 11 and the electrical devices 10, the meteorological evaluation system 28 and the operator of the public electricity network 24 for example. This evaluation and management unit 16 can be installed on the site 1 or remotely.

[0094] The evaluation and management unit 16 is configured to implement an evaluation method for evaluating the photovoltaic electricity production of the electricity production unit 12, in particular of the electricity production unit 12, by using a database 30 containing pre-recorded values of the photovoltaic electric power produced as a function of the irradiance for each day of the year and for different times of day.

[0095] To this end, the evaluation and management unit 16 is configured to access the database 30, which can be saved in the memory of the evaluation and management unit 16 (as illustrated schematically in Figure 2 ) or on a remote server.

[0096] According to a first embodiment, the pre-recorded values correspond to the photovoltaic electric power values produced by the electricity production unit 12 as a function of the irradiance.

[0097] In Figure 3 the table of the database 30 is shown in tabular form.

[0098] The database 30 contains photovoltaic electric power values generated as a function of the irradiance for each day of the year and for different times of day.

[0099] More particularly, the database 30 comprises, on the ordinate 32, irradiance levels in increments of, for example, 10 W / m 2 In the present embodiment, the irradiance values range from 0 to 1300 W / m 2 , in the present example from 0 to 1100 W / m 2 . This range of levels appears to be sufficient, since the maximum value of the irradiance of a surface orthogonal to the direct rays of the sun is generally of the order of 1000 W / m 2 .

[0100] The abscissa 34 shows the times of day, for example indexed by date and time, in a year. In the present embodiment, in the table of the database 30, there is each day of the year (from 1 January (01 / 01) to 31 December (12 / 31)), and for each day, different times of day indexed by the hour are shown, for example twenty-four times of day from 00:00 to 23:00 at one-hour intervals.

[0101] Obviously, the database table 30 can be modified without going beyond the scope of the application. Thus, the time intervals between the various times of day can be longer or shorter than one hour, and there can be more (or less) than twenty-four times of day per day. Moreover, it is also possible to index only the times of day that are between sunrise and sunset in the table of the database 30 (which can easily be determined by astronomical calculation), implicitly ignoring the nighttime hours when the irradiance value is zero or negligible.

[0102] Thus, for at least the daytime times of day between sunrise and sunset, Figure 3 the photovoltaic electric power values 36 generated as a function of the irradiance 32 are given in the database 30, the time intervals between these daytime times of day being preferably regular and ranging between 30 minutes and 2 hours, in particular 1 hour.

[0103] More particularly, each day of the year can be divided into hours, i.e. 8760 time intervals for a common year.

[0104] For each time of day and each irradiance level indexed in the database 30, in the range from 0 to 1100 W / m 2 and in increments of 10 W / m 2The electric power values 36 corresponding to the photovoltaic electric power generated by the electric power generation unit 12 are pre-recorded for incremental units.

[0105] Thus, if a global level of irradiance of 470 W / m 2 is received at 12:00 on 01 / 01, for example, the photovoltaic electric power generated by the electric power generation unit 12 can be evaluated at 3305573 kW, for example. At 16:00, this same irradiance generates a photovoltaic electric power of 2325012 kW.

[0106] Thus, it is evident that, based on the irradiance values, which can be predictive or historical values, the photovoltaic electric power generated by the electric power generation unit 12 can be very easily evaluated.

[0107] Thus, for astronomical reasons, according to the date and the predetermined geographical region, the database 30 takes into account the angle formed between the direct rays of the sun and the surface of the photovoltaic module 14, which varies according to the season and the time of day.

[0108] If the irradiance value 32 determined by the meteorological evaluation system 28 is not exactly one of the pre-recorded irradiance levels in the database 30, a linear correction can be made to approximate these photovoltaic electric powers 36 generated under individual conditions, by interpolation methods, for example.

[0109] A predicted irradiance 32 of 468 W / m 2 at a given time of day, for example, 10:00 on 20 July, is used as an example. In such a case, the following calculations can be made:

[0110] [mathematical formula 1]

[0111]

[0112] where:

[0113] - P1 corresponds to the photovoltaic electric power 36 generated corresponding to the predicted irradiance 32 at the given time T; and

[0114] - E e corresponds to the predicted irradiance value 32.

[0115] According to the data in Figure 3 at 10:00 on 20 July:

[0116]

[0117] On the other hand, if the time chosen for the evaluation of the electric power is not exactly the time given by the database of Figure 3 , a linear correction can also be made to determine the photovoltaic electric power 36 generated at this exact time.

[0118] For example, the prediction of the irradiance 32 can be made at 10:15 on July 20. In such a case, in order to predict the photovoltaic electric power 36 produced on July 20 at that precise time and for a predetermined time interval, the following calculations can be made:

[0119] [mathematical formula 2]

[0120]

[0121] where:

[0122] - P2 corresponds to the photovoltaic electric power produced at a specific time of the day for a given irradiance.

[0123] According to the data in 2 : Figure 3 For 10:00:

[0124]

[0125] For 11:00:

[0126]

[0127] Thus for 10:15:

[0128]

[0129]

[0130] Since the correction in this example is linear, the correction can be made first on the irradiance level and then on the time of the interval, or vice versa.

[0131] According to a second embodiment, which makes it possible to further reduce the size of the database 30, the pre-recorded values correspond to the coefficients of a mathematical function, in particular for example a fourth-degree polynomial function, which describes the photovoltaic electric power values produced as a function of the irradiance values, the range of which is between 0 and 1300 W / m 2 .

[0132] For example, if the values of the photovoltaic electric power 36 as a function of the irradiance level 32 are plotted for different times of the day, i.e. the graphs shown in Figure 4 are obtained.

[0133] Thus, the curves 41 (triangles), 43 (diamonds), 45 (squares) and 47 (circles) respectively show the values of the photovoltaic electric power 36 as a function of the irradiance level 32 for the following times: 01 / 01 at 12:00, 01 / 01 at 16:00, 07 / 20 at 10:00 and 07 / 20 at 11:00.

[0134] ​Using a mathematical function such as a least square regression with an interpolating fourth degree polynomial function, it is possible to determine the coefficients to be recorded in advance as values in the database 30, to calculate the photovoltaic electric power generated by the power generation unit 12 as a function of the irradiance.

[0135] More specifically, the calculated values of the model described in the following paragraphs illustrated in Figure 4 a fourth degree polynomial, by least square regression. The polynomial is written as:

[0136] P(Ee) = A x Ee 4 + B x Ee 3 + C x Ee 2 + D x Ee + E

[0137] By this regression, for a time of the year, it is possible to derive the 5 coefficients A, B, C, D and E to be recorded in the database 30, as illustrated in Figure 5 Figure 5 shows an example of expression and content of this database 30 in the form of a table with different coefficients.

[0138] Still in this embodiment, for each day of the year and for different times of the day, the database 30 comprises a set of coefficients, for example A, B, C, D, E, which allow to calculate the photovoltaic electric power value as a function of the irradiance by means of a mathematical function.

[0139] For an irradiance 32 from a measurement or a forecast, to evaluate the photovoltaic electric power of the power generation unit 12, it is only necessary to find in the database 30 the coefficients A to E corresponding to the time of evaluation and use these coefficients to calculate the electric power 36 in the polynomial. For example, to determine the electric power 36 at 10 o'clock on July 20, the coefficients A to E extracted from the database for this time of the year are respectively: -4.6074 x 10 -6 , 3.1851 x 10 -3 , 3.4227 x 10 0 , 4.7805 x 10 3 , 0 x 10 0 . Then the photovoltaic electric power 36 for a GHI irradiance of 468 W / m 2 is: P(468) = -4.6074 x 10 -6 x 468 4 + 3.1851 x 10 -3 x 468 3 + 3.4227 x 10 0 x 468 2 + 4.7805 x 10 3 x 468 + 0 x 10 0 ​= 3092387 kW

[0140] In contrast to the first embodiment, the method does not require interpolation of the irradiance to deal with precise irradiance levels. On the contrary, as mentioned above, interpolation must always be performed in order to evaluate the electric power at a time instant between two time intervals of the database. In the aforementioned embodiment, in order to evaluate the electric power at 10:15 under a GHI of 468 W / m 2

[0141] P2(10:00) = 3092387 kW

[0142] P2(11:00) = 3048581 kW

[0143]

[0144] i.e. only 0.5% difference compared to the first embodiment.

[0145] This second embodiment of the database 30 describes the performance of the power generation unit 12 as a function of irradiance and time, which is more compact since there are only 5 pre-recorded numerical values for each time interval, instead of 111 in the case of a database with increments of 10 W / m 2 2 between 0 and 1100 W / m 2 , i.e. approximately 22 times less storage requirement.

[0146] The performance of the electric power 36 as a function of the irradiance 32 can be described using a mathematical model other than a fourth-degree polynomial, by using other mathematical functions or other regressions or other methods for determining the coefficients. The method chosen will affect the size of the database and the computational capacity requirements.

[0147] Thus, the photovoltaic power of the power generation unit 12 at every time instant of the year and for all irradiance conditions can be accurately evaluated.

[0148] In order to make this evaluation as accurate as possible, as will be explained in detail below, particular attention is paid to the calculation and creation of the database 30.

[0149] Creating and using a database 30

[0150] Figure 6The operation blocks that allow the creation of database 30 are presented in a simplified and schematic manner. Block B1 represents the pre-modeling of the aforementioned energy supply facility 11, especially the power generation unit 12 as a whole, and block B2 represents a known adjustment or simulation program in the prior art, such as the commercial product PVSYST, PVSOL, or the academic product SAM or the collaborative product LADYBUG. Such modeling takes into account multiple parameters, such as, in particular, the characteristics of the photovoltaic modules 14, their arrangement / orientation / tilt on site 1, and their quantity and efficiency.

[0151] The modeling also includes a description of the wiring between the photovoltaic modules 14, as well as a description of the power conversion equipment used (inverters, controllers, transformers, etc.).

[0152] Modeling can also take into account the environment, such as occlusion from a distance or near and self-occlusion.

[0153] Once the modeling is complete, the numerical value used to determine the photovoltaic power generated by the power generation unit 12 is calculated and recorded in database 30, which is relative to the irradiance value represented by block B4. Figure 3 The embodiments shown) or the coefficients of the mathematical function ( Figure 5 The embodiment shown) and all predetermined times throughout the year (represented by block B3) are modeled according to time intervals defined by the user or software, wherein the irradiance values ​​(e.g., GHI) are particularly between 0 and 1100 W / m². 2 Between and at 10W / m 2 As an increment, this allows the above to be obtained. Figure 3 Or the table in database 30 in 5.

[0154] Therefore, this calculation is performed, in particular, using known software for adjusting and modeling photovoltaic facilities, taking into account the specific configuration of the power generation unit 12 on site 1.

[0155] These calculations, which are relatively energy-intensive in terms of power consumption and specialized software, are performed only once to create database 30. As described above, subsequent evaluations are achieved by simply reading or interpolating the values ​​in database 30. Moreover, the creation of database 30 is facilitated because modeling of the power supply facility 11 is often required at least once before it is deployed and assembled on site 1, especially for cost-benefit studies.

[0156] One of the advantages of using such a database 30 is that predictive or historical irradiance values ​​directly take into account some meteorological phenomena, such as clouds.

[0157] Photovoltaic power generation assessment method

[0158] Figure 7An embodiment of an evaluation method for evaluating the photovoltaic electricity production of an energy supply installation 11 installed on a site 1 is shown.

[0159] According to a step El, past or predictive irradiance values are determined for the time interval of the day for the site 1 on which the energy supply installation 11 is installed, between one second and two days or even two years. This step El is carried out in particular by the provision of irradiance values by the meteorological evaluation system 28 to the evaluation and management unit 16 by means of the remote communication means 26.

[0160] In the aspect of the predictive evaluation, the determination of the irradiance and of the other meteorological parameters is carried out in a predictive time interval between one second and two days, in particular less than 5 minutes. Obviously, the shorter the predictive time interval, the more reliable the prediction of the irradiance values. The interval between two irradiance value predictions can be chosen according to the requirements, for example one prediction every 10 seconds in the case of the management of a local electricity grid 22, as will be explained below.

[0161] In the aspect of the historical evaluation, the collected meteorological parameters can be taken in successive time intervals of the past between a few minutes and a few days.

[0162] The determination of the meteorological parameters (prediction or collection) in a given predictive time interval is carried out in a time interval shorter than or equal to the given predictive time interval, generally between one second and a few hours.

[0163] The produced photovoltaic electric power is then evaluated during a step E2 according to the determined irradiance values, the time of the year at which the evaluation is carried out and the pre-recorded produced electric power values 36 in the database 30, either by simple reading or by calculation using the mathematical functions and coefficients as detailed in the two embodiments above, linear interpolation being carried out if necessary on the irradiance 32 or on the time of the year 34.

[0164] According to an optional step E3, a step of correction of the pre-recorded values 36 of the produced photovoltaic electric power in the database 30 is applied by taking into account the values of the predicted, past or measured temperature (in particular the temperature of the modules 14 or the ambient temperature on the site 1) and / or the wind speed values on the installation site 1, using a correction coefficient, in particular a linear correction coefficient.

[0165] Indeed, the photovoltaic modules 14, in particular the cells that make them up, are components for which the photovoltaic conversion efficiency is almost linearly dependent on the operating temperature of the cells. Secondly, the ambient temperature can limit the conversion efficiency of the energy converters, for example the inverters.

[0166] The temperature can be determined for example by means of a temperature sensor fixed to the modules 14 and connected to the evaluation and management unit 16, or the temperature can be the result of meteorological prediction calculations transmitted by the meteorological evaluation system 28.

[0167] Therefore, by cyclically performing steps E1 and E2 or E1 to E3 at sampling intervals of 5 minutes or less, especially per second, accurate and rapid photovoltaic power generation assessments can be achieved.

[0168] If the sampling interval of the received irradiance, temperature, or wind speed values ​​exceeds the sampling interval of the assessment calculation (i.e., the interval between two irradiance value determinations is longer than the interval between two power generation assessments), a first approximate linear interpolation can be used to refine the calculation.

[0169] Using a database 30, for example, in tabular form, to determine the theoretical photovoltaic power 36 generated by the power generation unit 12 in the past or future by simply determining (predictive or historically collected) irradiance allows for a minimum limitation of the required computational power. Thus, using such a database 30 facilitates calculations and therefore allows for a simpler and faster determination of the photovoltaic power 36 generated by the power supply facility 11 at any time of day and year. Using this database 30 allows for near-instantaneous assessment of the generated power, which is not feasible with adjustment procedures known in the prior art.

[0170] Moreover, using such a database 30 allows for the automatic determination of the photovoltaic power theoretically generated by the power supply facility 11 at fine sampling intervals of 5 minutes or less, especially per minute.

[0171] The evaluation calculations can also be performed on physical machines or virtual machines in the cloud, which is not always feasible for, for example, commercial photovoltaic adjustment software.

[0172] These assessments can be used for management, such as local power grid 22, or for operational control on power generation unit 12.

[0173] Managing a local power grid 22

[0174] Figure 8 An embodiment of a method for predicting photovoltaic power generation and managing electrical equipment is shown, which is implemented, for example, by an assessment and management unit 16 to manage the local power grid 22.

[0175] According to Figure 7 Step E1, similar to step F1, involves collecting predictive meteorological parameters (e.g., irradiance values, temperature at site 1, and wind speed at site 1) for site 1 where the power supply facility 11 is installed. The values ​​of these predictive meteorological parameters are provided, for example, by the meteorological assessment system 28. This is followed by steps E2 and E3 (E3 is optional), as described above in conjunction with... Figure 5 As described. Finally, during step F4, the assessment and management unit 16 is configured to control the local power grid 22 based on the forecast of photovoltaic power generation from the power supply facility 11.

[0176] This control of the local electrical network 22 can involve one or more of the following actions, which list is not exhaustive, for example:

[0177] - regulating the consumption of one or more electrical devices 10,

[0178] - storing electrical energy in the storage unit 18 and / or injecting electrical energy from the storage unit 18,

[0179] - starting or stopping one or more thermoelectric generators 20,

[0180] - drawing electrical power from the public electrical network 24 or injecting electrical power into the public electrical network 24.

[0181] Method for monitoring and diagnosing power generation

[0182] The sensitivity, speed and low consumption of the calculation capacity also allow the use of said evaluation method in a method for monitoring and diagnosing photovoltaic production of the energy supply installation 11 installed on the site 1, as schematically shown according to the embodiment of Figure 9 The speed and saving calculation of this method allow the use of limited calculation resources to frequently monitor a large number of sites. According to a step G1 similar to the step E1 in Figure 7 , historical meteorological parameters (for example irradiance values, temperature on the site 1 and wind speed on the site 1) are collected for the site 1 on which the energy supply installation 11 is installed. The values of the historical meteorological parameters are for example provided by a meteorological evaluation system 28 working on satellite images. According to a variant not shown, these historical values can be provided by sensors on the site 1 and recorded in a memory of for example the evaluation and management unit 16. This is followed by steps E2 and E3 (E3 being optional) as described above in connection with Figure 7 These steps E2 and E3 thus allow to provide a reference value which is the value that the energy supply installation 11 should produce according to the irradiance and the temperature, if necessary. Then, during a step G4, the evaluation and management unit 16 is configured to compare the photovoltaic production evaluated on the basis of the historical meteorological data with the actual photovoltaic production measured over a past time interval.

[0183] Finally, according to a step G5, the evaluation and management unit 16 is configured to generate a warning if the difference between the evaluated photovoltaic production and the photovoltaic production measured over the past time interval exceeds a predetermined threshold.

[0184] Indeed, if the measured value is significantly lower than the theoretical value (for example 10%), it can be deduced that the energy supply installation 11 has a malfunction requiring a maintenance operation, for example the presence of dust or dirt on the photovoltaic modules 14 or the failure of a chain of modules 14.

[0185] The historical meteorological parameters can be acquired with high precision and / or in large quantities of data. Therefore, using the same computing power, it is possible to evaluate the theoretical electric power more finely over a period of time or over longer time intervals.

[0186] Obviously, therefore, one of the determining factors of the present application lies in the use of the database 30 and in the choice of how to organize it to be able to evaluate the electric power produced with pre-recorded values that allow to determine the specific photovoltaic electric power of the plant 11 on the site 1 based on few variables, such as the time of the year (allowing to take into account the astronomical and geographical date + time) and the irradiance (allowing to take into account the meteorological and astronomical aspects), or based on the coefficients as described above.

[0187] Moreover, for the frequency of iteration in the method for predicting the photovoltaic electric power, some short-term meteorological fluctuations, such as the passage of a cloud that causes a reduction in the irradiance on the photovoltaic modules 14 of the electric power unit 12, can also be captured and used to predict the photovoltaic electric power produced by the energy plant 11.

[0188] Similarly, since the calculation times are short, it is possible to read the meteorological parameters sufficiently frequently and close to each other over the time interval involved, so that the short-term meteorological fluctuations are less disturbing for the evaluation of the theoretical power.

[0189] Therefore, the evaluation calculation can be carried out on a physical machine or on a virtual machine in cloud computing.

[0190] The above-described embodiments are provided as non-limiting examples.

Claims

1. A method for evaluating the photovoltaic production of an energy supply installation (11) installed on a site (1), said energy supply installation (11) comprising at least one production unit (12) comprising at least one photovoltaic module (14); said method for evaluating the photovoltaic production comprising the steps of: - determining past or predictive irradiance values for the site (1) on which the energy supply installation (11) is installed, this determination being made over a time interval of between one second and two years, and - evaluating the photovoltaic electric power produced as a function of the determined irradiance values and of values previously recorded in a database (30), said database (30) comprising values previously recorded for each day of the year and for different times of day, which make it possible to determine the photovoltaic electric power produced as a function of the irradiance, the values previously recorded in the database (30) corresponding to the coefficients of a mathematical function describing the value of the electric power produced as a function of the irradiance. characterized in that The mathematical function is a polynomial. The method comprises a step of correcting the photovoltaic electric power produced as a function of the irradiance, this correction step taking into account the predictive, past or measured temperature and / or wind speed values on the installation site (1) by applying a correction coefficient. The correction coefficient is a linear correction coefficient. wherein said database (30) comprises, for each instant comprised in said database (30), the electric power values generated as a function of different irradiance levels ranging from 0 to 1300 W / m 2 For an irradiance level not given in said database (30) for a given time, but situated between two levels given in said database (30), the photovoltaic electric power value is determined by linear interpolation of the photovoltaic electric power values indicated by said database (30) for the two irradiance levels.

2. The photovoltaic power generation evaluation method according to claim 1, wherein The values previously recorded in the database (30) are given at least between sunrise and sunset each day, the time interval between these diurnal times being between 5 minutes and 2 hours.

3. The photovoltaic power generation evaluation method according to claim 2, wherein For the diurnal times not given in the database (30) and situated between two times given in the database (30), the values previously recorded are determined by linear interpolation of the values previously recorded indicated at the two times given in the database (30).

4. The photovoltaic power generation evaluation method according to claim 3, wherein The coefficients of the mathematical function are determined by least square regression on the generated electric power values as a function of different irradiance values ranging from 0 to 1300 W / m 2 .

5. The photovoltaic power generation evaluation method according to claim 1 or 2, characterized by, The sampling interval over which the production is evaluated is less than or equal to five minutes.

6. The photovoltaic power generation evaluation method according to claim 5, wherein 10. A method for predicting the photovoltaic production and for managing electrical equipment for an energy supply installation (11) equipped with at least one electrical equipment (10) on a site (1) on which the energy supply installation is installed, said energy supply installation (11) comprising at least one production unit (12) comprising at least one photovoltaic module (14), comprising the steps of: - performing a method for evaluating the photovoltaic production as claimed in any one of claims 1 to 9, in which, in the step of determining the irradiance values, predictive irradiance values are determined for the site (1) on which the energy supply installation (11) is installed, this determination being made over a predictive time interval of between one second and two days, and - adjusting the operating mode of at least one electrical equipment (10) as a function of the evaluation of the photovoltaic production of the energy supply installation (11).

7. The photovoltaic power generation evaluation method according to claim 1 or 2, characterized by, 11. A method for monitoring and diagnosing the photovoltaic production of an energy supply installation (11) installed on a site (1), said energy supply installation (11) comprising at least one production unit (12) comprising at least one photovoltaic module (14), said method comprising the steps of:

8. The photovoltaic power generation evaluation method according to claim 7, wherein ​ 9. The photovoltaic power generation evaluation method according to claim 1 or 2, characterized by, ​ ​ ​ ​ ​ ​ - performing a photovoltaic power production evaluation method as claimed in any one of claims 1 to 9, wherein, in said step of determining an irradiance value, for a past time interval, a historical irradiance value of a site (1) where said energy supply installation (11) is installed is determined, and - comparing the evaluated photovoltaic power production with the photovoltaic power production measured in the past time interval.

12. The method of monitoring and diagnosing of claim 11, wherein, The method further comprises a step of generating a warning if the difference between the evaluated photovoltaic power production and the photovoltaic power production measured in said past time interval exceeds a predetermined threshold.

13. An evaluation and management device comprising means configured to implement the method as claimed in any one of claims 1 to 12.

14. A computer program product, loadable into the internal memory of an evaluation and management device comprising portions of software code for performing the steps of the method as claimed in any one of claims 1 to 12 when said computer program is executed by a computer.

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