System for monitoring partial discharges in an electrical installation by means of gaseous emissions

Abstract

A method for monitoring partial discharge (PD) in an electrical installation (1), the electrical installation (1) comprising at least one electrical room (2), the electrical room (2) comprising at least one piece of medium voltage or high voltage electrical equipment (3).

Description

Technical Field

[0001] The present invention relates to a system and a method for monitoring partial discharges in at least one piece of medium voltage or high voltage electrical equipment.

[0002] The invention also relates to an electrical installation comprising such a monitoring system. Background Art

[0003] Medium and high voltage electrical equipment are often subject to high current and voltage levels and partial discharges may occur.

[0004] In the following, the terms "medium voltage" and "high voltage" are used as generally accepted, that is, "medium voltage" refers to voltages above 1000 volts AC and 1500 volts DC but not above 52000 volts AC and 75000 volts DC, and the term "high voltage" refers to voltages strictly above 52000 volts AC and 75000 volts DC.

[0005] A partial discharge is a local discharge that, under the action of high voltage, shorts out parts of the insulating material that separates the conductive material.

[0006] Partial discharges can be caused, inter alia, by manufacturing defects, uncontrolled environmental conditions or material wear.

[0007] For example, partial discharges in dielectric materials can occur in gas bubbles: Since the dielectric constant of the gas is much lower than that of the surrounding material, the electric field generated is significantly higher than the electric field present in the insulating material. If the voltage exceeds the dielectric strength limit of the gas contained in the gas bubble, a partial discharge occurs. Conversely, the presence of conductive particles in an insulator can also lead to partial discharges.

[0008] Other types of partial discharges may occur on the surface of insulating materials or in the surrounding gas through corona discharge.

[0009] There are therefore two types of partial discharges: internal partial discharges, which occur inside the insulating material, and external partial discharges, which occur on the surface of the insulating material or in the gas immediately surrounding the insulating material.

[0010] These partial discharges may increase the rate of deterioration of the dielectric strength of the insulating material, for example by promoting corrosion or oxidation of the material. In the medium and / or long term, this deterioration may become severe and eventually lead to breakdown of the insulating material terminals and damage to the electrical equipment.

[0011] This increases the safety risk to the electrical equipment and therefore to people working nearby.

[0012] In order to limit this risk, various methods are known for monitoring partial discharges in a piece of electrical equipment, for example electrical, acoustic or optical methods.

[0013] Document EP 3 258 278 A1 therefore proposes a method based on an acoustic analysis which is correlated with the measured values ​​from temperature and humidity sensors.

[0014] Document EP1593981A2 proposes a method based on the analysis of voltage and current signals when partial discharge occurs.

[0015] Chemical methods can also be used. Specifically, external partial discharges can lead to chemical reactions on the surface of insulating materials of electrical equipment or in the surrounding gas (especially air). These chemical reactions lead to the formation of gaseous elements, especially ozone.

[0016] Therefore, the document “Characterization of medium voltage equipment ageing by monitoring of partial discharges chemical and acoustical emission, E. Odic, E. Jouseau, G. Vivien, CS. Maroni, 10th International Electrical Insulation Conf. INSUCON 2006, Birmingham: United Kingdom (2006)” proposes a method for monitoring partial discharges using an ozone sensor.

[0017] However, this approach does not allow to identify the specific causes of partial discharges, but measures to limit their occurrence may depend on these causes.

[0018] Furthermore, this approach has been shown to be inaccurate in certain circumstances. Specifically, the concentration of the gaseous element measured by the sensor may vary over time, for example due to other human activities in the vicinity of the electrical equipment, regardless of the occurrence or absence of a partial discharge.

[0019] For example, it is known that some industrial plants or motor vehicle traffic may emit ozone precursors, such as nitrogen oxides, hydrocarbons or volatile organic compounds. These ozone precursors may react to form ozone, in particular under the influence of ultraviolet radiation from the sun.

[0020] Therefore, by measuring a high concentration of a gas element such as ozone regardless of the occurrence or non-occurrence of a partial discharge in the electrical equipment, a measurement value from the sensor for the gas element may be distorted.

[0021] One of the objects of the present invention is therefore to find a simple, reliable and economical system capable of detecting the occurrence of partial discharges in an electrical installation in order to determine its cause and ensure the effectiveness of the method used.

[0022] Furthermore, gaseous elements produced in partial discharges may have significant health effects, for example by promoting bronchial inflammation or scarring of lung tissue in persons working near electrical equipment.

[0023] It is therefore another object of the present invention to allow continuous and real-time monitoring in order to detect potentially dangerous partial discharges. Summary of the invention

[0024] The present invention improves this situation.

[0025] Proposed is a method for monitoring partial discharges in an electrical installation, the electrical installation comprising at least one electrical room comprising at least one piece of medium-voltage or high-voltage electrical equipment, the electrical installation comprising:

[0026] - at least one set of first sensors arranged inside the electrical room and at least one set of second sensors arranged outside the electrical room, each of the first and second sets of sensors comprising at least one sensor for a gas element;

[0027] - at least one temperature sensor and / or humidity sensor arranged inside the electrical installation,

[0028] The method comprises at least the following steps:

[0029] a1) comparing the concentrations of gas elements obtained using the first set of sensors and the second set of sensors;

[0030] a2) determining, based on the comparison in step a1), whether a change in the concentration of the gas element acquired by the first group of sensors is caused by factors external to the electrical installation;

[0031] b1) comparing the concentration of the gas element obtained by the first group of sensors with the measurement values ​​from the temperature sensor and / or the humidity sensor;

[0032] b2) determining, based on the comparison in step b1), whether the change in the concentration of the gas element acquired by the first group of sensors is due to a change in temperature and / or humidity inside the electrical installation; and

[0033] c) If the response to steps a2) and b2) is negative, it is inferred that the concentrations of the gaseous elements obtained by the first set of sensors originate from factors internal to the electrical installation.

[0034] Through these arrangements, it is possible to distinguish between partial discharges caused by external factors of the electrical equipment (such as specific environmental conditions inside the electrical installation that may promote the occurrence of one-time partial discharges) and partial discharges caused in particular by internal factors of the electrical equipment (such as wear on the materials of the electrical equipment).

[0035] Optionally, the features disclosed in the following paragraphs may be implemented. These features may be implemented independently of each other or in combination with each other:

[0036] According to one embodiment, the sensors for gas elements in the first group of sensors and the second group of sensors are selected from an ozone sensor, a carbon monoxide sensor, a nitric acid sensor and a nitrogen oxide sensor.

[0037] According to another embodiment, if the response to step b2) is positive, the method further comprises a step b3) of regulating the environmental conditions inside the electrical installation.

[0038] According to another embodiment, if the response to step b2) is negative, the method further comprises a step c') of determining the state of wear of the material of the piece of electrical equipment from the concentrations of the gaseous elements obtained by the first set of sensors.

[0039] According to another embodiment, if the concentration of the gas element obtained by the first set of sensors is higher than a threshold value, the method further comprises a warning step d).

[0040] According to another embodiment, the internal factor is wear and tear of the piece of electrical equipment.

[0041] Therefore, the "difference" or relative analysis between sensors installed inside and outside the electrical room can ensure that the electrical facilities are satisfactorily maintained. By analyzing the absolute concentration, the concentration of gas elements can be monitored, thereby protecting the safety of personnel working near electrical facilities when necessary.

[0042] According to another aspect, proposed is a system for monitoring partial discharges in an electrical installation, the electrical installation comprising at least one electrical room comprising at least one piece of medium voltage or high voltage electrical equipment, the system comprising:

[0043] - at least one set of first sensors arranged inside the electrical room and at least one set of second sensors arranged outside the electrical room, each of the first and second sets of sensors comprising at least one sensor for a gas element;

[0044] - at least one temperature sensor and / or humidity sensor arranged inside the electrical installation,

[0045] - a processing unit comprising a processor configured to implement at least the following steps:

[0046] a1) comparing the concentrations of gas elements obtained using the first set of sensors and the second set of sensors;

[0047] a2) determining, based on the comparison in step a1), whether a change in the concentration of the gas element acquired by the first group of sensors is caused by factors external to the electrical installation;

[0048] b1) comparing the concentration of the gas element obtained by the first group of sensors with the measurement values ​​from the temperature sensor and / or the humidity sensor;

[0049] b2) determining, based on the comparison in step b1), whether the change in the concentration of the gas element acquired by the first group of sensors is due to a change in temperature or humidity inside the electrical installation; and

[0050] c) If the response to steps a2) and b2) is negative, it is inferred that the concentrations of the gaseous elements obtained by the first set of sensors originate from factors internal to the electrical installation.

[0051] According to one embodiment, the system comprises a warning device.

[0052] According to another embodiment, the system includes one or more actuators configured to adjust environmental conditions within the electrical installation. BRIEF DESCRIPTION OF THE DRAWINGS

[0053] Other features, details and advantages will become apparent upon reading the description provided below and upon reviewing the accompanying drawings, in which:

[0054] Figure 1 is a schematic diagram of a facility according to one embodiment of the present invention.

[0055] Figure 2 is a schematic diagram of a monitoring method according to an embodiment of the present invention. DETAILED DESCRIPTION

[0056] The following drawings and descriptions mostly contain certain characteristic elements, so they contribute not only to a better understanding of the invention but also, where appropriate, to its definition.

[0057] Figure 1 Schematically shown is a substation or installation 1 comprising one or more pieces of electrical equipment 3 (or electrical devices 3) arranged in an electrical room 2. One or several electrical rooms 2 may be arranged in the electrical installation 1.

[0058] according to Figure 1 In the illustrated embodiment, the electrical installation 1 includes three pieces of electrical equipment 3 arranged in a single electrical room 2 .

[0059] The electrical installation 1 may be a station in a power grid for power transmission and / or distribution. The electrical equipment 3 may be selected from switches, circuit breakers, contactors, fuse switches, reclosers or disconnectors. However, other types of electrical equipment 3 are also possible.

[0060] In a manner known per se, the electrical equipment 3 comprises a variety of metallic materials, such as steel, copper or aluminium, or insulating materials, such as elastomers, resins or EPDM. However, it is certainly possible to use other types of materials, the dielectric strength of the material being more specifically selected according to the target application of the electrical equipment.

[0061] The electrical installation 1 comprises a system for monitoring partial discharge (PD), in particular external partial discharge. The monitoring system comprises at least one first group of sensors 4 (hereinafter referred to as "first group") and a second group of sensors 5 (hereinafter referred to as "second group").

[0062] The first group 4 is arranged inside the electrical room 2 , in particular near the electrical equipment 3 , while the second group 5 is arranged outside the electrical room 2 , in particular inside and / or outside the electrical installation 1 .

[0063] according to Figure 1 In the illustrated embodiment, the first group 4 includes sensors arranged at each piece of electrical equipment 3 , and the second group 5 includes sensors arranged inside and outside the electrical installation 1 .

[0064] The first group 4 comprises at least one sensor Cg for a gaseous element.

[0065] The sensor Cg for the gas element is configured to measure the concentration or the change in concentration of the gas element. The gas element may be selected from ozone (O 3 ), carbon monoxide (CO), nitric acid (HNO 3 ) and nitrogen oxides (NO x ). Advantageously, the gas element is ozone, which is one of the first gases produced during the external partial discharge. However, other gas elements are also conceivable.

[0066] The first group 4 also comprises at least one temperature sensor Ct and / or a humidity sensor Ch. Advantageously, the first group 4 comprises both a temperature sensor Ct and a humidity sensor Ch.

[0067] The first group 4 may also include one or more other additional sensors configured to acquire environmental measurements such as pressure, altitude or other measurements. These additional sensors may allow the electrical installation 1 specific climatic conditions to be taken into account when analyzing the acquired measurements, for example according to its geographical location.

[0068] The first set of sensors 4 may be arranged in the electrical room 2, in particular in close proximity to the electrical equipment 3. The first set of sensors 4 may, for example, be arranged in contact with the electrical equipment 3, in particular on an outer wall of the electrical equipment 3, or in close proximity to the electrical equipment 3, in order to measure the concentration or changes in concentration of gaseous elements found in the air around the electrical equipment 3.

[0069] The second group 5 comprises at least one sensor Cg for a gas element. In the same manner as the first group 4, the sensor Cg for a gas element is configured to measure the concentration or the change in the concentration of the gas element. The gas element may be selected from ozone (O 3 ), carbon monoxide (CO), nitric acid (HNO 3 ) and nitrogen oxides (NO x ). Thus, the second group 5 advantageously comprises the same sensors for gas elements as the first group 4 .

[0070] The second group 5 , located outside the electrical room 2 , makes it possible to measure the concentration or the change in concentration over time of the gaseous elements independently of the operation of the electrical equipment 3 and the occurrence of partial discharges.

[0071] In particular, as indicated above, the concentrations of some gaseous elements may vary from day to day or from season to season, for example due to human activities in the environment near the electrical installation 1. The second group 5 allows taking these variations into account.

[0072] In the same way as the first group 4, the second group 5 may also comprise at least one temperature sensor Ct and / or humidity sensor Ch. Advantageously, the second group 5 comprises both a temperature sensor Ct and a humidity sensor Ch.

[0073] The system further comprises a processing unit 6. The processing unit 6 is configured to analyse and process the measurements once they have been acquired by the various sensors of the first set 4 and the second set 5.

[0074] The processing unit 6 thus comprises a communication interface 7 configured to receive the measurements acquired by the sensors. The communication between the processing unit 6 and the sensors may be wired or wireless, in particular via a short range protocol such as Bluetooth, Sigfox, LoRa or the like.

[0075] The communication interface 7 also makes it possible to send / receive information from a remote server 8. The remote server 8 can thus be configured to remotely analyze and process the measurements acquired by the sensors in combination with or as an alternative to the processing unit 6. The communication between the processing unit 6 and the remote server 8 can be wired or wireless, in particular via a remote protocol such as Ethernet or 3G / 4G / 5G.

[0076] The processing unit 6 further comprises a processor 9 configured to analyse, advantageously in real time, the measurements acquired by the sensors. The processor 9 may use mathematical or algorithmic tools, in particular by using artificial intelligence.

[0077] By real time it is understood that the method according to the invention is implemented during the operation of the electrical installation 1 , within fixed time limits.

[0078] The processing unit 6 further comprises a memory 10 configured to store measurement values ​​acquired by the sensors over time.

[0079] The system further comprises one or more warning devices 11 configured to warn personnel working on the electrical installation 1, in particular using sound, light, messages etc., in particular in case of high concentrations of gaseous elements, as will be described below.

[0080] The system further comprises one or more actuators 12. The actuators 12 are configured to control and / or adjust environmental conditions inside the electrical installation 1, and more specifically, to control and / or adjust environmental conditions inside the electrical room 2. The actuators 12 may, for example, control heating, cooling, humidification or dehumidification equipment inside the electrical installation 1.

[0081] Combine the following Figure 2 A method according to the invention for monitoring partial discharges inside an electrical installation 1 is described.

[0082] In step 100 , the system checks the integrity and correct operation of the electrical installation 1 , in particular the integrity and correct operation of the monitoring system. Specifically, in step 101 , the system checks the correct operation of the first group 4 and the second group 5 .

[0083] If the sensor is not working or has a problem communicating with the processing unit 6 , the system sends a warning message via the warning device 11 in step 102 .

[0084] If no problem is detected, the system proceeds to step 103 of acquiring measurements from the sensors. These measurements may be stored in the memory 10 of the processing system 6 and / or on the remote server 8 (step 104).

[0085] In step 105 , the system compares the measurements taken between the first set of sensors 4 and the second set of sensors 5 .

[0086] As described above, some gas elements, such as ozone, may be generated by partial discharges, but may also be generated by other factors outside the electrical facility 1 and unrelated to the electrical facility 1. Therefore, it is necessary to compare the concentration of the gas element obtained by the first group 4 located in the electrical room 2 with the concentration of the gas element obtained by the second group 5 located outside the electrical room 2. This comparison may be performed remotely by the processor 9 of the processing unit 6 and / or the remote server 8 (steps 105 and 106).

[0087] By "external factors" is understood a concentration of gaseous elements which is partially or completely caused by the occurrence of partial discharges or other situations which are independent of the state or operation of the electrical installation 3. Thus, external factors are, for example, environmental and climatic conditions which affect the interior of the electrical installation 1 or gaseous elements which are emitted by elements independent of the electrical installation 1.

[0088] In contrast to external factors, "internal factors" are understood to be partial or total causes of the concentration of gaseous elements related to the state or operation of the electrical equipment 3. Internal factors are, for example, wear and tear of the electrical equipment 3 or manufacturing defects.

[0089] If this comparison indicates a difference less than a given threshold value and / or a correlation in terms of concentration and time between the measurements taken by the first set 4 and the second set 5, it can be concluded that the concentrations of the measured gaseous elements are due to factors external to the electrical installation 1. They are therefore not related to the partial discharges occurring inside the electrical room 2.

[0090] If the comparison indicates a difference greater than a given threshold and / or a lack of correlation in terms of concentration and time between the measurements taken by the first 4 and second 5 sets, it can be concluded that the concentration of the gaseous element is due to a partial discharge occurring in the electrical chamber 2 .

[0091] Then, in step 107 , the system sends a warning message via the warning device 11 .

[0092] These partial discharges may in particular be caused by internal factors, in particular by wear of insulating materials of the electrical equipment 3 .

[0093] According to one embodiment (not shown), the system can measure the degradation of the material of the electrical equipment 3, in particular the degradation caused by oxidation, based on the concentration of the gaseous elements obtained by the sensor. Therefore, the degradation of the electrical equipment 3 can be estimated by taking into account the known model of wear and aging of the material.

[0094] In particular, the order of appearance and the relative concentrations of the various gaseous elements make it possible to determine the kinetics of the chemical reactions following a partial discharge and to improve the estimation of the degradation of the material of the electrical equipment 3 under consideration.

[0095] However, these partial discharges may also be prompted by external factors, such as certain specific environmental conditions inside the electrical installation 1, in particular regarding temperature and humidity inside the electrical room 2. In particular, the amplitude or frequency of partial discharges may increase or decrease if the temperature and / or humidity vary.

[0096] If the sensor shows a correlation between the ambient conditions (particularly temperature or humidity) and the concentration of the gaseous element inside the electrical installation 1 (step 108), it can be concluded that the partial discharge is due to the ambient conditions inside the electrical installation 1. In step 109, the system sends a warning message via the warning device 11.

[0097] For example, the concentrations of gaseous elements may be compared to known threshold concentrations of these same gaseous elements that are typically observed at a given temperature or humidity inside the electrical installation 1 .

[0098] If the sensors show an insufficient correlation, it can be concluded that the partial discharge is due to internal factors, such as wear on the material of the electrical equipment 3. It is therefore necessary to perform maintenance on the electrical equipment in order to ensure the safety and correct operation of the installation.

[0099] In addition, in step 111, the system evaluates whether the concentration of the gaseous elements inside the electrical installation 1 may have a negative impact on the health of personnel working inside the electrical installation 1. In case the concentration is above a given threshold, the system then sends a warning message via the warning device 11 in step 112.

[0100] according to Figure 1 In the embodiment shown, in which the electrical installation 1 comprises an actuator 12, the system may allow, in step 113, the environmental conditions inside the electrical installation 1 to be controlled and / or regulated in order to limit the risks associated with partial discharges. Thus, the system is able to regulate the temperature and humidity in the electrical installation 1 in order to reduce the occurrence of partial discharges and thus reduce the generation of gaseous elements.

[0101] The method can be implemented by a first set of sensors 4 arranged near each piece of electrical equipment 3. The arrangement of these sensors thus makes it possible to locate more precisely which piece of electrical equipment 3 or electrical room 2 more specifically needs to be monitored.

[0102] The method according to the invention makes it possible to improve the detection of partial discharges, determine their causes (in particular material wear or environmental conditions in the electrical room) and then perform actions inside the electrical installation 1 to limit the occurrence of new partial discharges or to warn the relevant personnel according to various alarm levels.

[0103] according to Figure 2In the embodiment shown, the method can then be repeated by returning to all or some of the above steps 100 to 113. Thus, the method is performed continuously.

[0104] By “continuously” it is understood that the method is advantageously carried out repeatedly during the entire operation of the electrical installation 1 .

[0105] Of course, the present invention is not limited to the above-mentioned embodiments, which are provided as examples only. The present invention covers various modifications, alternative forms and other variations that can be thought of by those skilled in the art in the context of the present invention, in particular any combination of the above-mentioned various embodiments, which can be used alone or in combination.

Claims

1. A method for monitoring partial discharges in an electrical installation (1), the electrical installation (1) comprising at least one electrical room (2), the electrical room (2) comprising at least one medium-voltage or high-voltage electrical equipment (3), the electrical installation (1) comprising: - at least one set of first sensors (4) arranged inside the electrical room (2) and at least one set of second sensors (5) arranged outside the electrical room (2), each of the first set of sensors (4) and the second set of sensors (5) comprising at least one sensor for a gas element; - at least one temperature sensor and / or humidity sensor arranged inside the electrical installation (1), The method is characterized in that the method comprises at least the following steps: a1) comparing the concentrations of gas elements obtained using the first set of sensors (4) and the second set of sensors (5); a2) determining, based on the comparison in step a1), whether the change in the concentration of the gas element acquired by the first group of sensors (4) is caused by factors external to the electrical installation (1); b1) determining whether there is a correlation between the concentration of the gas element obtained by the first group of sensors (4) and the measurement values ​​from the temperature sensor and / or the humidity sensor; b2) determining, based on the determination in step b1), whether the change in the concentration of the gas element acquired by the first group of sensors (4) is due to a change in temperature and / or humidity inside the electrical installation (1); and c) If the response to steps a2) and b2) is negative, it is inferred that the concentrations of the gaseous elements obtained by the first set of sensors (4) originate from internal factors of the electrical installation (1).

2. The method according to claim 1, wherein: The sensors for gas elements in the first group of sensors (4) and the second group of sensors (5) are selected from ozone sensors, carbon monoxide sensors, nitric acid sensors and nitrogen oxide sensors.

3. The method according to claim 1 or 2, wherein: If the response to step b2) is positive, the method further comprises a step b3) of regulating the environmental conditions inside the electrical installation (1).

4. The method according to claim 1 or 2, wherein: If the response to step b2) is negative, the method further comprises a step c') of determining the state of wear of the material of the piece of electrical equipment (3) based on the concentrations of the gaseous elements obtained by the first set of sensors (4).

5. The method according to claim 1 or 2, further comprising a warning step d) if the concentration of the gas element obtained by the first group of sensors (4) is higher than a threshold value.

6. The method according to claim 1 or 2, wherein: The internal factor is wear and tear on the piece of electrical equipment (3).

7. A system for monitoring partial discharges in an electrical installation (1), the electrical installation (1) comprising at least one electrical room (2), the electrical room (2) comprising at least one piece of medium voltage or high voltage electrical equipment (3), the system comprising: - at least one set of first sensors (4) arranged inside the electrical room (2) and at least one set of second sensors (5) arranged outside the electrical room (2), each of the first set of sensors (4) and the second set of sensors (5) comprising at least one sensor for a gas element, - at least one temperature sensor and / or humidity sensor arranged inside the electrical installation (1), - a processing unit (6) comprising a processor (9), the processor (9) being configured to implement at least the following steps: a1) comparing the concentrations of gas elements obtained using the first set of sensors (4) and the second set of sensors (5); a2) determining, based on the comparison in step a1), whether the change in the concentration of the gas element acquired by the first group of sensors (4) is caused by factors external to the electrical installation (1); b1) determining whether there is a correlation between the concentration of the gas element obtained by the first group of sensors (4) and the measurement values ​​from the temperature sensor and / or the humidity sensor; b2) determining, based on the determination in step b1), whether the change in the concentration of the gas element acquired by the first group of sensors (4) is due to a change in the temperature or humidity inside the electrical installation 1; and c) If the response to steps a2) and b2) is negative, it is inferred that the concentrations of the gaseous elements obtained by the first set of sensors (4) originate from internal factors of the electrical installation (1).

8. System according to claim 7, comprising a warning device (11).

9. System according to claim 7 or 8, comprising one or more actuators (12) configured to adjust environmental conditions inside the electrical installation (1).

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