Method for determining the operating state of an electrical transformer positioned within a distribution substation, device and corresponding computer program.

Abstract

The invention relates to a method for determining the operating state of an electrical transformer located within an enclosure comprising at least two ventilation grilles. According to the invention, such a method comprises: a step of obtaining (S02, S03) at least two pairs of representative temperature data measured at two different locations within the enclosure; a calculation step (S051, S052), from said at least two pairs of representative temperature data, of at least two transformer temperatures ( , ); using said at least two transformer temperatures, a determination step (S053) of the operating state of an electrical transformer. Fig. 2

Description

Title of the invention: Method for determining the operating state of an electrical transformer located within a distribution substation, device and corresponding computer program. Scope of the invention

[0001] The field of invention is that of electrical equipment in the distribution network. The present invention relates to an in-situ diagnostic device for assessing the health status of distribution transformers in high-voltage AC (HV) / low-voltage (LV) substations using a limited number of measurements. Previous Art

[0002] Distribution substations are components of the electrical distribution network, ensuring the conversion of medium voltage to low voltage to supply the majority of electricity consumers. Several hundred thousand of them are installed in each European country. A transformer, which provides galvanic isolation between the upstream and downstream voltage levels, is positioned inside these distribution substations. The distribution substation, acting as an enclosure for the transformer, provides a certain degree of physical protection for it, as well as ventilation.

[0003] The transformer often consists of a sealed metal tank containing a magnetic circuit in the shape of an inverted figure eight, with three columns corresponding to the three phases of the transformer. Each column is wound with a medium-voltage winding and a low-voltage winding, made of copper or aluminum. These windings are separated by electrotechnical paper impregnated with a dielectric liquid contained in the tank, thus forming a paper-dielectric liquid complex that determines the dielectric strength of the transformer, that is, its ability to withstand dielectric stresses.

[0004] The dielectric fluid also plays a role as a heat transfer fluid by transmitting the heat generated by Joule losses in the conductors and iron losses in the magnetic circuit to the metal tank for cooling by heat exchange with the surrounding environment of the transformer station, this environment being naturally ventilated by the thermal draft created by the shape of the station and the ventilation grilles.

[0005] The end of a transformer's life is reached when its dielectric strength is no longer sufficient, resulting in internal breakdown, i.e., current flowing between two windings or between a winding and the metal core of the tank. The indicators of Aging factors are chemical in nature, such as the degree of paper polymerization and the moisture content in the dielectric fluid. However, these indicators are not accessible in MV / LV distribution transformers because they are sealed. Manufacturers' recommendations and standards for using these transformers only cover limited situations and do not take into account the different operating regimes of the transformer.

[0006] The thermal loop describing the heat exchange within the transformer is described in standards (notably IEC 60076-7:2018-01), with established relationships between the oil temperature at the top of the tank, called the "top oil" temperature, and the hot spot temperature, generally located at two-thirds of the height of the central winding. Natural ventilation of the enclosure provides air circulation around the transformer, partially ensuring its temperature maintenance, and therefore the proper functioning and longevity of the equipment it contains.

[0007] The main problem of maintaining operational condition lies in the inability of the operator to determine the temperature of the "hot spot" in real time (independent of ambient temperature and load conditions) in order to maintain the transformer in optimal operating and aging conditions.

[0008] Thus, to guard against potential transformer failures, operators reduce the loads applied to them. Consequently, operators accept significant margins on transformers to maintain relatively low load factors at the peak load, preventing the hot spot temperature (Ths) from exceeding the threshold for dielectric strength degradation. This approach results in additional costs and does not provide solutions in many practical situations.

[0009] Indeed, many distribution stations are limited in their ventilation capacity by local problems (vegetation or posters obstructing the ventilation grilles) which degrades the transformer particularly during certain peak periods and / or periods of high heat.

[0010] Solutions for monitoring transformer temperature in real time have been considered. One solution involves instrumenting the transformer with fiber optics. This has the advantage of eliminating the need for data from the distribution substation, but raises the issue of the cost of implementing such a solution across the entire fleet of MV / LV substations. Furthermore, maintaining these measurements over the expected lifespan of a sealed MV / LV transformer, approximately forty years, would not be guaranteed, depriving the operator of the diagnostic and monitoring function or forcing them to replace the transformer at a cost. Another approach would be to apply to distribution transformers the monitoring devices used in some HV / MV transformers, based on taking samples of the dielectric fluid and analyzing them to track aging indicators. It should be noted that an HV / MV transformer (High Voltage B / High Voltage A) is a type of electrical transformer used in electricity distribution networks to step down the voltage from a high voltage level (HV) to a lower high voltage level (MV). Unlike MV / LV transformers, HV / MV transformers are not sealed and undergo dielectric fluid regeneration or top-up.Applying this type of device to a sealed transformer would create more problems than it solves and would be very costly compared to the price of MV / LV transformers (around ten thousand euros for an MV / LV transformer versus hundreds of thousands of euros for an HV / MV transformer).

[0011] The invention improves the situation. Summary of the invention

[0012] The invention aims to provide an in situ diagnostic solution for voltage transformers equipping a MV / LV distribution substation that can overcome at least one of the aforementioned drawbacks.

[0013] To this end, the invention proposes a method for determining the operating state of an electrical transformer positioned within an enclosure comprising at least two ventilation grilles. Such a method comprises the following steps: - a step of obtaining at least two pairs of data representative of temperatures measured at two different locations of the envelope station; - a calculation step, based on said at least two pairs of representative temperature data, of at least two transformer temperatures; - using the aforementioned at least two transformer temperatures, a step to determine the operating state of an electrical transformer.

[0014] The invention enables real-time monitoring of representative transformer temperatures ("hot spot" and "top-oil"), allowing for the diagnosis and monitoring of the transformer's health. Furthermore, these measurements are non-intrusive and require no additional sensors inside the equipment. Thus, the operator can make the best decisions regarding actions to ensure optimal operation of distribution substation transformers.

[0015] Such a method offers several advantages, depending on the operational implementation conditions and the features implemented, including real-time or semi-delayed monitoring. Furthermore, the measurements are performed without requiring additional sensors inside the transformer, thus reducing the costs and complications associated with the installation and maintenance of internal sensors. Moreover, by providing accurate data on the transformer's operating status, the method enables operators to make informed decisions to optimize transformer operation and maintenance. The method can be applied to different types of substation enclosures, making it adaptable to various environments and transformer configurations.Furthermore, by avoiding the need for preventative load reduction, the process maintains optimal load factors, thus reducing the additional costs associated with transformer underutilization. Finally, by monitoring representative temperatures, the process helps prevent potential failures due to overheating, thereby extending transformer lifespan.

[0016] According to a particular feature, the first location is at the level of the first ventilation grille and the second location is at the level of the second ventilation grille.

[0017] By positioning the temperature sensors at the two ventilation grilles, the method makes it possible to capture the temperature variations of the air entering and leaving the substation enclosure. This improves the accuracy of ambient temperature measurements around the transformer, which is important for calculating internal transformer temperatures, such as the "hot spot" and the "top-oil".

[0018] According to a particular feature, the two pairs of representative measured temperature data are obtained at two different times separated by a predetermined duration.

[0019] Thus, by obtaining temperature data at two different times separated by a predetermined duration, the method makes it possible to monitor the evolution of temperatures over time. This facilitates the analysis of thermal variations and improves the accuracy of diagnosing the operating condition of the transformer, taking into account thermal dynamics and changing load conditions.

[0020] According to a particular feature, the calculation step of said minus two transformer temperatures implements a numerical model.

[0021] According to a particular characteristic, the digital model uses parameters which are obtained from at least one data representative of the identification of the envelope post.

[0022] According to a particular characteristic, the calculation step is carried out as a function of a data representative of a load factor experienced by the envelope substation.

[0023] According to another aspect, the invention also relates to a device for determining the operating state of an electrical transformer positioned within an enclosure comprising at least two ventilation grilles. Such a device comprises: - means of obtaining at least two pairs of representative temperature data measured at two different locations of the envelope station; - means of calculating, from said at least two pairs of representative temperature data, at least two transformer temperatures; - means of determining the operating state of an electrical transformer using at least two transformer temperatures.

[0024] Such a device also includes, depending on the embodiment, a processor and memory, located locally. It can take the form of a diagnostic case. It includes, for example, two temperature sensors suitably positioned at the distribution substation, a power measurement module (load factor) which transmits data through the substation, retrieving this information from the substation's intelligent equipment if it is equipped with such equipment, or current and voltage sensors enabling the retrieval of this information, Analog-to-Digital Converters (ADCs) for pre-processing the measurements, and a microcontroller (MC) in which ADC data processing software is implemented to generate a diagnostic and output indicator, either in the form of a light or an HMI.

[0025] When the device is used with a remote server and the only modules present on site are the temperature measurement modules, the implementation follows these steps: temperature sensors installed on the ventilation grilles measure temperatures at regular intervals. This data is collected locally by a measurement module; the measured temperature data is transmitted to the remote server via a communication network (Wi-Fi, 3G / 4G / 5G, etc.); communication modules, integrated into the transformer substation, ensure this transmission; the remote server receives the temperature data and uses processing software to perform the necessary calculations; this includes calculating the internal temperatures of the transformer (such as the "hot spot" and "top-oil") and assessing the operating status of the transformer; the remote server analyzes the processed data to diagnose the health status of the transformer.It can also use digital models to simulate operating conditions and predict maintenance needs; diagnostic results and recommendations are sent to operators via a remotely accessible user interface; this may include. alerts in case of detection of abnormal conditions; operators use the information provided to make informed decisions regarding the operation and maintenance of transformers, thus optimizing their performance and lifespan.

[0026] According to a preferred implementation, the various steps of the processes according to this disclosure are implemented by one or more software or computer programs, comprising software instructions intended to be executed by a data processor of an electronic resource consumption measurement device or, more generally, of a communicating object according to this technique and designed to control the execution of the various steps of the processes, implemented at the level of the electronic resource consumption measurement device or the communicating object, a remote server and / or a resource consumption management / monitoring system or communicating objects, within the framework of a distribution of the processing to be carried out and determined by a scripted source code or a compiled code.

[0027] Consequently, the present technique also relates to programs, capable of being executed by a computer or by a data processor, these programs comprising instructions to control the execution of the steps of the processes as mentioned above.

[0028] A program may use any programming language, and be in the form of source code, object code, or intermediate code between source code and object code, such as in a partially compiled form, or in any other desirable form.

[0029] The present technique also relates to an information carrier readable by a data processor, and comprising instructions of a program as mentioned above.

[0030] The information medium can be any entity or terminal capable of storing the program. For example, the medium can include a storage means, such as a ROM, for example a CD ROM or a microelectronic circuit ROM, or a magnetic recording means, for example a mobile medium (memory card) or a hard disk or an SSD.

[0031] On the other hand, the information medium can be a transmissible medium such as an electrical or optical signal, which can be transmitted via an electrical or optical cable, by radio, or by other means. The program according to the present technique can, in particular, be downloaded onto an Internet-type network.

[0032] Alternatively, the information carrier may be an integrated circuit in which the program is incorporated, the circuit being adapted to execute or to be used in the execution of the process in question.

[0033] According to one embodiment, the present technique is implemented using software and / or hardware components. In this context, the term "module" in this document may refer to a software component, a hardware component, or a set of hardware and software components.

[0034] A software component corresponds to one or more computer programs, one or more subroutines of a program, or more generally to any element of a program or software capable of implementing a function or set of functions, as described below for the module concerned. Such a software component is executed by a data processor of a physical entity (terminal, server, gateway, set-top box, router, etc.) and is capable of accessing the hardware resources of that physical entity (memory, storage media, communication bus, input / output electronic cards, user interfaces, etc.).

[0035] Similarly, a hardware component corresponds to any element of a hardware assembly capable of implementing a function or a set of functions, as described below for the module concerned. It may be a programmable hardware component or one with an integrated processor for software execution, for example an integrated circuit, a smart card, a memory card, an electronic card for executing firmware, etc.

[0036] Each component of the system described above naturally implements its own software modules.

[0037] The different embodiments mentioned above can be combined with each other for the implementation of the present technique. Brief description of the figures

[0038] Other objects, features and advantages of the invention will become more apparent upon reading the following description, given by way of simple illustrative, and not limiting, example, in relation to the figures, among which: - [Fig. 1] represents a transformer model, including the differential equations allowing the obtaining of characteristic values, according to the disclosure; - [Fig.2] illustrates the algorithm implemented within the disclosure mechanism; - [Fig.3] schematically illustrates a disclosure device.

[0039] Description of an embodiment

[0040] The disclosure device includes means for real-time estimation of key temperatures of a distribution transformer ("hot spot" and "top-oil") by measuring temperatures at the level of the two ventilation grilles, the measurement of Its load and the information on its nameplate are taken into account. This information is processed by software that calculates in real time the exceedance of the dielectric strength thresholds of the paper-dielectric liquid complex of the transformer and the transformer's aging rate. The measurements performed are non-intrusive and do not require additional sensors placed within the equipment, which significantly reduces the cost of the solution.

[0041] The thermal model of the transformer conforming to IEC 60076-7:2018-01 is a dynamic model that allows the operating temperatures of the transformer to be calculated, in particular the hot spot temperature and the top-oil temperature. The thermal model can be represented by an equivalent circuit consisting of two RC circuits in series: - oil circuit: represents the thermal behavior of the oil; - winding circuit: represents the thermal behavior of the windings.

[0042] Each circuit comprises: - a thermal resistance R; - a thermal capacity C; - a source of heat (losses).

[0043] The model allows the following temperatures to be calculated: - top-oil temperature (Tto): temperature of the oil at the top of the tank; - Hotspot temperature (Ths): highest temperature in the windings; - Hot spot temperature gradient (A0h): difference between Ths and Tto.

[0044] The model of a disclosure distribution transformer is shown in Figure 1. The process implemented by the disclosure device is illustrated in Figure 2. In the model in Figure 1, Tamb denotes the ambient temperature, Tto the top-oil temperature, and Ths the hot-spot temperature. The notation A x0y denotes the temperature difference, in kelvin, between Tx and Ty. This model includes the following parameters: - kJ |, coefficient of acceleration of the oil temperature rise, - k2t, coefficient indicating the proportion of the temperature increase in the windings that is tempered by the oil circulation, - k22, coefficient of acceleration of the temperature rise in the windings, - Temperature, characteristic time of oil temperature rise under normal operating conditions transitional, - characteristic temperature rise time of the windings, - A Oor, parameter designating A amb0to at nominal power and in steady state, - A 0^, parameter designating A to0hs at nominal power and in steady state, - exponent, which characterizes the increase of A to0hs in steady state depending on the load factor, - x, the exponent, which characterizes the increase of A amb0to in steady state according to the power dissipated, - K, load factor, - R75, ratio of pressure losses to no-load losses, for K = 1 and a average winding temperature of 75°C.

[0045] These parameters and constants are generally determined by tests or estimated from transformer characteristics, for example, those found on its nameplate, at the substation level. The standard model considers the overheating of the device as a function of an ambient temperature Tamb. In the laboratory, or in open air, this temperature Tamb corresponds to the outside temperature. However, this is not the case within an enclosure-type substation.

[0046] The inventors determined, however, that it was possible to estimate the ambient temperature from measurements taken by two strategically placed thermal probes. Thus, a thermal coupling between the ambient temperature of the transformer and the outside temperature (measured at two different locations within the substation) is implemented. The inventors have therefore developed a method for evaluating these aspects from temperature measurements taken in situ at the substation, namely at the two ventilation grilles. To this end, a coupling is implemented between the substation (at which the temperatures are measured) and the transformer (the transformer whose condition is to be assessed).The coupling allows measurements taken outside the substation to be converted to values ​​representative of the situation inside the substation, and thus to be able to loop back to the transformer model of the IEC 60076-7:2018-01 standard.

[0047] Indeed, it is possible to equate the ambient temperature with the outside (weather) temperature when the transformer is in open air. However, this is not true within a ventilated enclosure (frame). The temperature inside the enclosure does not determine the reference level to be considered within the device. Air movement constantly brings fresh air into contact with the transformer. of the device. The ambient temperature is thus similar to a "perceived" temperature, cooler than the temperature inside the unit.

[0048] Without defining and estimating this ambient temperature within the substation enclosure, it would be necessary to internally instrument the transformer (optical fibers, for example) to access Ths (hotspot), which is economically impractical given the number of transformers installed. The disclosure device is described in relation to [Fig. 3].

[0049] Thus, the disclosure device is equipped, for example, with two temperature probes (St1, St2) that allow the device to receive, at predetermined time intervals (for example, every fifteen minutes), a temperature measurement at each ventilation grille of the transformer substation, for example, the lower grille and the upper grille. The lower grille measures the air inlet temperature of the transformer substation. The upper grille measures the air outlet temperature of the transformer substation. The two temperature probes (St1, St2) are connected to an analog-to-digital converter (ADC). The disclosure device also includes an electronic module comprising a memory M, a processing unit P equipped, for example, with a microprocessor, and controlled by a computer program Pg.The analog-to-digital converter (ADC) transmits temperature data to the processing unit P, which also receives an evaluation of the transformer load via a load measurement module CL. Furthermore, the device may also include communication means (CIE), such as network components (Wi-Fi, 3G / 4G / 5G, wired, RFID / NFC, Bluetooth, BLE, LPWAN, VLC, etc.), enabling the device to receive data from entities connected to one or more communication networks and to transmit processed data to such entities, for example, remote servers. In some embodiments, the device may include a keyboard and / or a screen, or means of connection to a portable terminal, for example, for inputting and / or displaying measured or calculated temperatures, as explained in relation to the equations and the process described herein.

[0050] Furthermore, the current load measurement module CL of the transformer (power), can for example be in the form of an interface allowing it to be obtained directly from a measuring equipment present on the transformer station, or in the form of an association of current and voltage sensors with which the device is equipped.

[0051] The inlet and outlet temperature data of the transformer substation, as well as the load, are used to perform a simple and efficient calculation, which is based not only on these measurements, but also on the transformer parameters (which are accessible via its nameplate).

[0052] A heat removal equation for the transformer substation is considered to be given by: [°O53] pT = - PT, power dissipated in W;

[0054] PT = Pfe + R75 xK2 - T<ext>, average outside temperature at the MV / LV substation; - Tin, internal temperature of the MV / LV substation, at mid-height of the transformer, which depends on the temperature stratification inside the substation; ^ <ext>6in, temperature difference T^^-T^. - Pfe, no-load losses (or "iron" losses), which occur within the ferromagnetic core and are constant regardless of the transformer's load regime, - R75, Pressure losses for K = 1 and an average temperature of 75° windings - K, the load factor continuously measured by the disclosure device, is the ratio of the measured power to the transformer's rated power (which is known for the transformer)

[0055] . Thus, the first of these two equations relies on two parameters: the conduction coefficient 4>c and the ventilation coefficient (j>v). However, evaluating these parameters requires detailed knowledge of the structure. It would be necessary to have precise measurements of the substation, the location of the grilles, their profile, the buried height, the transformer height, the wall thickness, the material they are made of, etc. This information is beyond the scope of an on-site evaluation.However, the device of the invention must be able to evaluate these coefficients to allow coupling with the model and thus to enable the evaluation of the conditions experienced within the transformer (by solving the appropriate differential equations). In the absence of knowledge of <|)c and $, the heat dissipation equation of the transformer substation has two unknowns (<])ç and (|>v) because it is assumed that Aæxt>0m are known using the measurement performed with the device of the invention. However, an equation with two unknowns cannot be solved uniquely: it has an infinite number of solutions.

[0056] The inventors determined that in order to allow the solution of this equation, it was necessary to perform a temporal duplication.

[0057] Let li and t2 be two consecutive distinct measurement times performed by the device which is the subject of this document. For clarity, each value measured at h is indexed to 1 and each value measured at t2 is indexed to 2.

[0058] The previous heat evacuation equation from the transformer station can, on the one hand, undergo a transformation at the level of the variables and, on the other hand, be subject to temporal duplication.

[0059] Thus, we note:

[0060] A T|=(14i)(Tsl-Tel)

[0061] A 1-,= (14 nlfe-rj

[0062] In which: - H; is the height of the enclosure of the MV / LV transformer substation; - h; is the height of the MV / LV transformer (inside the substation) transformation); - Such; is the temperature at the inlet grid at time t]; - Tsl; is the temperature at the outlet grid at time; - Te2: is the temperature at the inlet grid at time; - Ts2: is the temperature at the outlet grid at time t2;

[0063] Thus, we obtain the following two equations: [0064l P,, = ([rAPP AT, + 4>)PP( AT,)' [°°651 AT!+eW

[0066] The following quantities are calculated at different measurement times:

[0067] , \2 at time tj; PI1 = Pfe+R75 x(Kj

[0068] , \2 at time L; PT, = Pfe +r75 x(Kj

[0069] Considering the two coefficients sought (|>APP and (j)APP as variables of the system of equations, we obtain: [0°7°] APP (at^at^ T,, — , ,3 / 2 / ,3 / 2 c AT^AT,) -AT / ATj)

[0071] .app at^-ata, Q) — / ,3 / 0 (v AT / ATJ TATJAT,) "

[0072] Once the duplication is applied to the in situ transformer substation, the model treats the transformer substation as an avatar: the conventional transformer substation that would exhibit identical behavior over the time interval [trt?]. The model only assesses the consequence of the actual configuration: does it ensure an ambient temperature in the substation that conforms to the duly qualified ideal configuration?

[0073] In other words, when the time duplication method is used on the on-site transformer substation, the mathematical model treats this substation as if it were a standard transformer substation. This standard transformer substation is defined by ideal and uniform characteristics, such as a parallelepiped shape, not adjoining any building, with unobstructed ventilation grilles ideally positioned on two separate vertical walls. Thus, the method only considers the results of temperature and load measurements to assess whether the ambient temperature inside the transformer substation conforms to that of an ideal substation. This simplifies the analysis by eliminating the need for specific details about the actual design and construction of the transformer substation. Therefore, the model can operate effectively without needing to know the exact parameters of the actual transformer substation..

[0074] Instead of directly measuring key temperatures (and in particular the ambient temperature inside the substation), this ambient temperature is estimated using an energy balance (heat balance). This is a simple and effective approach for covering possible substation architectures since it does not consider their design and construction parameters (size, materials, etc.) but only the heat exchanges at the MV / LV substation level.

[0075] Thus, the device of the invention is implemented by positioning the two temperature probes it carries at the two ventilation grilles of the transformer substation. Iterative temperature readings are taken at the inlet and outlet of the transformer substation, as well as power readings (obtained either directly via a suitable interface or by determining the voltage and current). The time interval at which the various measurements are taken is variable and depends primarily on the specific conditions. As an example, a time interval of 15 minutes between two measurements can be considered.

[0076] In any event, once the first measurement is taken at li, the input temperature Tel and output temperature Tsl values ​​of this first measurement are recorded in memory. The device of the invention then enters a data processing loop at a predefined time step. Within this loop, at the next time interval, the output temperature (Ts2,... T^, T^p) is compared to the previous output temperature to determine if stable output temperatures are observed, in which case no calculations are necessary (steady state).

[0077] When a difference in outlet temperature is observed (e.g., Tsl < Ts2), the inlet and outlet temperatures at two successive time steps are used, in

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[0090] in accordance with the previously described model, to calculate the various model temperatures and assess the transformer's aging. To do this, as explained previously, in addition to the load factor, information relating to the substation (and / or transformer) markings is used. Thus, the analytical solution of equations (la) (1b) and (2), from figure 1, describing the model implemented within the disclosure, is as follows, and comprises two groups of equations (depending on whether the temperatures are measured during load increase -group I - or load decrease -group II): Regarding the temperature rise of the metal in the windings (la): I. During a load increase: A 01 ( t ) = A tm ) + {k21 A 0hrKy - A 0] ( tm )} x [ 1 - ] I. During a load decrease: AO^t) =k21A6hrKy+ { -k21AehrKy} For cooling metal with oil (1b): I. During a load increase: A 02 ( t ) = A 02 ( tm ) + {(k21 -1) A 0bïKy - A e2 ( tm )} x [ 1 - ] I. During a load decrease: A02(t) = (ler 1)A6^+ { A02(td) - (k -1) A 0hrKy 1 x^2) J l 21 / J For the oil (2): I. During a load increase: A anA( t ) = A amb0to( tm ) + A 0OT I. During a load decrease: [1+R--K2 ( F 1+R--K2 TT ] + ( A amb0îo ( td ) - A 0or x [ ] | x T In these equations, tm denotes the instant of the start of the load ramp-up, td the instant from the beginning of a load decrease. When the plateau is maintained, either equation (ascent or descent) can be used: the result will be equivalent. During an increase in load, the algorithm uses the equations labeled I. During a decrease in load, it uses the equations labeled IL. Then, a representative data point regarding the ventilation efficiency of the transformer substation is obtained. This data is displayed (and / or transmitted) to allow an operator to take the necessary measures if required.

[0091] In relation to [Fig.2], the process implemented within the device includes: - a data acquisition step (SOI) representative of the transformation station; - an acquisition step (S02) of a first pair of input temperature data Tel and output temperature Tsl - an acquisition step (S03) of a second pair of input temperature Te2 and output temperature Ts2 data - a comparison step (S04) of the first outlet temperature and the second outlet temperature;

[0092] When it is determined that these two temperatures are different, the implementation (S05) of the following steps: - determination of a representative data of a load factor (S051); - calculation of temperatures (S052), using an implementation of the equations previously presented (group of equations I or group of equations II); - evaluation (S053) of the aging of the transformer station as a function of the calculated temperatures; - optionally, determination (S054) of the efficiency of heat removal by the transformer station.

[0093] Following the execution (S05) of the preceding calculation, the data representing the calculated values ​​are displayed (either on the device itself or on a remote system). A new execution can be performed, for example, if longer monitoring is planned. In this case, the pair of second temperature values ​​at time t2 replaces, in memory, the pair of first temperature values ​​at time h, and a new iteration of steps S03 to S05 is carried out. These iterations can continue as long as necessary. A history of the measurements and calculations can be maintained to keep track of the changes associated with this transformer substation.

[0094] Thus, the disclosure method and device provide a simple and easily deployable diagnostic and monitoring solution. This solution can be deployed on a large scale both on new MV / LV substations (for example, by equipping substations during construction with temperature sensors on the ventilation grilles and equipping these transformers with a communication interface to transmit the measured data) and on existing substations (by implementing measurement campaigns using portable devices as described above), and allows the network operator to monitor the health of the transformers and optimize its interventions. More generally, the disclosure solution applies to any type of MV / LV substation housing a transformer.< / ext> < / ext>

Claims

Demands

1. Method for determining the operating state of an electrical transformer positioned within an enclosure substation comprising at least two ventilation grilles, the method comprising: - a step of obtaining (S02, S03) at least two pairs of representative temperature data measured at two different locations of the enclosure substation; - a step of calculating (S051, S052), from said at least two pairs of representative temperature data, at least two temperatures of the transformer (Tto, Ths); - using said at least two temperatures of the transformer, a step of determining (S053) the operating state of an electrical transformer.

2. A method according to claim 1, characterized in that the first location is at the level of the first ventilation grille and in that the second location is at the level of the second ventilation grille.

3. A method according to any one of claims 1 and 2, characterized in that the two pairs of representative measured temperature data are obtained at two different times (b, t2) separated by a predetermined duration.

4. A method according to any one of claims 1 to 3, characterized in that the calculation step (S051, S052) of said two transformer temperatures (Tto, Ths) implements a numerical model.

5. Method according to claim 4, characterized in that the digital model uses parameters which are obtained from at least one data representative of the identification of the envelope post.

6. A method according to any one of claims 1 to 5, characterized in that the calculation step (S051, S052) is carried out as a function of a data representative of a load factor (K) undergone by the envelope station.

7. Device for determining the operating state of an electrical transformer positioned within an enclosure comprising at least two ventilation grilles, the device comprising:

8.

9. - means of obtaining (SO2, SO3) at least two pairs ((teE Tsi), (Te2, TS2)) of representative temperature data measured at two different locations of the envelope station; - calculation means (S051, S052), from said at least two pairs of representative temperature data ((teE ^si), (TE2, TS2)), of at least two transformer temperatures (Tto, Ths); - means of determining (S053) the operating state of an electrical transformer using at least two transformer temperatures. Computer program comprising instructions for implementing the method according to any one of claims 1 to 6, when said instructions are executed by a processor of a computer processing circuit. Data carrier on which a computer program according to the preceding claim is recorded.

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