FI20225037A1 - Substation monitoring system - Google Patents

Substation monitoring system Download PDF

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Publication number
FI20225037A1
FI20225037A1 FI20225037A FI20225037A FI20225037A1 FI 20225037 A1 FI20225037 A1 FI 20225037A1 FI 20225037 A FI20225037 A FI 20225037A FI 20225037 A FI20225037 A FI 20225037A FI 20225037 A1 FI20225037 A1 FI 20225037A1
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FI
Finland
Prior art keywords
substation
partial discharge
sensor
monitoring system
processor
Prior art date
Application number
FI20225037A
Other languages
Finnish (fi)
Inventor
Jarkko Kuntanen
Kari Tuominen
Pekka Mikkola
Ilkka Virtanen
Original Assignee
Utu Oy
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Utu Oy filed Critical Utu Oy
Priority to FI20225037A priority Critical patent/FI20225037A1/en
Priority to SE2330024A priority patent/SE2330024A1/en
Publication of FI20225037A1 publication Critical patent/FI20225037A1/en

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Classifications

    • GPHYSICS
    • G01MEASURING; TESTING
    • G01RMEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
    • G01R31/00Arrangements for testing electric properties; Arrangements for locating electric faults; Arrangements for electrical testing characterised by what is being tested not provided for elsewhere
    • G01R31/12Testing dielectric strength or breakdown voltage ; Testing or monitoring effectiveness or level of insulation, e.g. of a cable or of an apparatus, for example using partial discharge measurements; Electrostatic testing
    • GPHYSICS
    • G01MEASURING; TESTING
    • G01RMEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
    • G01R31/00Arrangements for testing electric properties; Arrangements for locating electric faults; Arrangements for electrical testing characterised by what is being tested not provided for elsewhere
    • G01R31/12Testing dielectric strength or breakdown voltage ; Testing or monitoring effectiveness or level of insulation, e.g. of a cable or of an apparatus, for example using partial discharge measurements; Electrostatic testing
    • G01R31/1227Testing dielectric strength or breakdown voltage ; Testing or monitoring effectiveness or level of insulation, e.g. of a cable or of an apparatus, for example using partial discharge measurements; Electrostatic testing of components, parts or materials
    • G01R31/1263Testing dielectric strength or breakdown voltage ; Testing or monitoring effectiveness or level of insulation, e.g. of a cable or of an apparatus, for example using partial discharge measurements; Electrostatic testing of components, parts or materials of solid or fluid materials, e.g. insulation films, bulk material; of semiconductors or LV electronic components or parts; of cable, line or wire insulation
    • G01R31/1272Testing dielectric strength or breakdown voltage ; Testing or monitoring effectiveness or level of insulation, e.g. of a cable or of an apparatus, for example using partial discharge measurements; Electrostatic testing of components, parts or materials of solid or fluid materials, e.g. insulation films, bulk material; of semiconductors or LV electronic components or parts; of cable, line or wire insulation of cable, line or wire insulation, e.g. using partial discharge measurements
    • GPHYSICS
    • G01MEASURING; TESTING
    • G01RMEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
    • G01R31/00Arrangements for testing electric properties; Arrangements for locating electric faults; Arrangements for electrical testing characterised by what is being tested not provided for elsewhere
    • GPHYSICS
    • G01MEASURING; TESTING
    • G01RMEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
    • G01R31/00Arrangements for testing electric properties; Arrangements for locating electric faults; Arrangements for electrical testing characterised by what is being tested not provided for elsewhere
    • G01R31/12Testing dielectric strength or breakdown voltage ; Testing or monitoring effectiveness or level of insulation, e.g. of a cable or of an apparatus, for example using partial discharge measurements; Electrostatic testing
    • G01R31/1209Testing dielectric strength or breakdown voltage ; Testing or monitoring effectiveness or level of insulation, e.g. of a cable or of an apparatus, for example using partial discharge measurements; Electrostatic testing using acoustic measurements
    • GPHYSICS
    • G01MEASURING; TESTING
    • G01RMEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
    • G01R31/00Arrangements for testing electric properties; Arrangements for locating electric faults; Arrangements for electrical testing characterised by what is being tested not provided for elsewhere
    • G01R31/12Testing dielectric strength or breakdown voltage ; Testing or monitoring effectiveness or level of insulation, e.g. of a cable or of an apparatus, for example using partial discharge measurements; Electrostatic testing
    • G01R31/1227Testing dielectric strength or breakdown voltage ; Testing or monitoring effectiveness or level of insulation, e.g. of a cable or of an apparatus, for example using partial discharge measurements; Electrostatic testing of components, parts or materials
    • HELECTRICITY
    • H02GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02HEMERGENCY PROTECTIVE CIRCUIT ARRANGEMENTS
    • H02H1/00Details of emergency protective circuit arrangements
    • H02H1/0007Details of emergency protective circuit arrangements concerning the detecting means
    • H02H1/0015Using arc detectors
    • H02H1/0023Using arc detectors sensing non electrical parameters, e.g. by optical, pneumatic, thermal or sonic sensors

Abstract

Disclosed is a substation (100) monitoring system for monitoring partial discharge in substation (200) equipped with transformer (202). Substation monitoring system comprises partial discharge monitoring device (102, 400) comprising at least one sensor that generates sensor data and at least one processor communicably coupled with at least one sensor, and communication module, communicably coupled to at least one processor and user device. Processor is configured to determine partial discharge value by processing sensor data. Sensor comprises at least: high frequency current transformer coil (104, 206, 300) and ultrasonic microphone (106, 208) configured to measure current spikes and pressure of sound of partial discharge, respectively. The Communication module is configured to transmit partial discharge value, received from at least one processor, to user device, wherein at least one processor or processor of user device is configured to trigger alarm (108) at user device when partial discharge value exceeds pre-defined threshold value.

Description

SUBSTATION MONITORING SYSTEM
TECHNICAL FIELD
The present disclosure relates generally to power engineering; and more specifically, to substation monitoring systems for monitoring partial discharges in substations, equipped with transformers, and for predictive maintenance of substation, such as substations in a remote location.
BACKGROUND
Insulation failure is one of the principal causes of forced outages in operating high voltage electrical equipment such as switchgears and transformers. The insulation failures result in considerable damage and lost revenues. One type of insulation failure may typically be weak spots, such as small air gaps or voids, in the insulation of the high voltage electrical equipment. Such small air gaps or voids result in small electrical current sparks, namely the partial discharge, in or on the surface of the insulation of the high voltage electrical insulation. Moreover, the partial discharge occurs across a localized area of the insulation between two conducting electrodes, without completely bridging the gap. Notably, partial discharges can be detected in order to efficiently plan maintenance and prevent potential failure of the system that may be of an irreversible nature, thereby resulting in interruption in transmission and high repair < costs. 7 Conventionally, methods aided with modern signal processing and = evaluation techniques are used for partial discharge testing of high
N voltage electrical eguipment. Typically, a conventional partial discharge 3 25 detector, employs a storage oscilloscope to visualize measured signals
N corresponding to the partial discharge, and transmits data corresponding
N to the measured signals to a computer for further evaluation. It will be appreciated that the partial discharge currents tend to be of short duration and have risen times in the nanosecond realm. Moreover, on an oscilloscope, the discharges appear as evenly spaced burst events that occur at the peak of the sinewave even though the random events are arcing or sparking. Notably, a usual way of quantifying partial discharge magnitude is in picocoulombs and displaying it with respect to time.
Normally, an automatic analysis of reflectograms collected during the partial discharge measurement (namely by time domain reflectometry (TDR)), allows to determine the location of insulation irregularities that are displayed in a partial discharge mapping format. Additionally, for fast verification of partial discharge activity from various types of equipment, a variety of handheld devices exist, such as PD Scan by Megger®, may be used. However, such handheld devices may only be used for field tests on site and lack real time monitoring of the electrical equipment.
Other conventional ways of detecting the partial discharges employs ultrasound. Notably, the ultrasound detects the acoustic partial discharge and can be employed in devices for on-site measurement of partial discharges. It will be appreciated that ultrasound is completely insensitive to electromagnetic interference in a properly shielded system and can localize the partial discharges based on the sound waves, thereby avoiding false alarms. Moreover, as compared to electrical measurements a further benefit of acoustic partial discharge detection is that its
N sensitivity does not depend on the capacity of the test object. However; = the acoustic partial discharge detection uses acoustic wave sensors, 7 having mechanical mechanism, that fails+te can detect any sound other = 25 than human audible sound of frequency range 20 - 20 kHz. 5 Moreover, apart from the aforesaid methods, i.e. the electrical
D measurement and acoustic measurement, contact measurement
S methods may be used for the partial discharge detection. Typically, contact measurement may be performed using devices such as touch sensors that measure partial discharges in the sensor in the freguency range of 20kHz - 300kHz, electromagnetic sensors, such as ultra-high frequency sensors, that measure partial discharges in the sensor in the frequency range of 300kHz - 1.5GHz, or Transient Earth Voltage devices that measure partial discharges in the sensor in the frequency range of 3
MHz - 100 MHz, and so forth. However, the said methods employ numerous devices, thus are bulky, less efficient and mostly operable for on-site monitoring. Furthermore, conventional methods of partial discharge detection fail to measure signal values before the actual irreversible failure and the resulting interruption and repair costs are realized.
Therefore, considering the foregoing discussion, there exists a need to overcome drawbacks associated with conventional partial discharge detection.
SUMMARY
The present disclosure seeks to provide a substation monitoring system.
The present disclosure seeks to provide a solution to the existing problem of inaccurate measurements of a partial discharge of a substation in a remote location. An aim of the present disclosure is to provide a solution that overcomes at least partially the problems encountered in prior art, and provides an improved substation monitoring system that detects the
N partial discharges from the substation in a remote location in real-time = and provides said data to operators for preventive maintenance of 7 substations.
E In an aspect, an embodiment of the present disclosure provides a 5 25 substation monitoring system for monitoring a partial discharge in a 3 substation equipped with a transformer, the substation monitoring
ES system comprising: - a partial discharge monitoring device comprising at least one sensor that generates sensor data and at least one processor communicably coupled with the at least one sensor, wherein the at least one processor is configured to determine a partial discharge value by processing the sensor data, and wherein the at least one sensor comprises at least: - a high frequency current transformer coil configured to measure current spikes of the partial discharge, wherein the current spikes range from medium to high frequency, and - an ultrasonic microphone configured to measure pressure of sound of the partial discharge, wherein the pressure of sound ranges from low to medium frequency; and - a communication module, communicably coupled to the at least one processor and a user device, wherein the communication module is configured to transmit the partial discharge value, received from the at least one processor, to the user device, wherein the at least one processor or a processor of the user device is configured to trigger an alarm at the user device when the partial discharge value exceeds a pre-defined threshold value.
In another aspect, an embodiment of the present disclosure provides a method for monitoring a partial discharge, using a substation monitoring system, in a substation eguipped with a transformer, the method comprising: 3 - arranging at least one sensor near the transformer, wherein the at
N least one sensor comprises a high freguency current transformer coil and ? an ultrasonic microphone; > 25 - measuring pressure of sound, ranging from low to medium
E freguency, of the partial discharge in a medium-voltage section of the 2 substation, using the ultrasonic microphone; 3 - measuring current spikes, ranging from medium to high frequency,
N of the partial discharge in a low-voltage section of the substation, using the high frequency current transformer coil;
- determining a partial discharge value by processing the sensor data, using the at least one processor communicably coupled with the at least one sensor; and - transmitting, via a communication module, communicably coupled 5 to the at least one processor and a user device, the partial discharge value, received from the at least one processor, to the user device; and - triggering an alarm, by the at least one processor or a processor of the user device, at the user device when the partial discharge value exceeds a pre-defined threshold value.
Embodiments of the present disclosure substantially eliminate or at least partially address the aforementioned problems in the prior art and provide an improved real-time monitoring of the substation using the aforementioned substation monitoring system. The substation monitoring system enables monitoring of the technical condition of the main components of the substation, such as transformers, disconnectors, and cable terminals, remotely, using the aforementioned partial discharge monitoring device. In this regard, the partial discharge monitoring device detects partial discharge simultaneously with the high frequency current transformer coil and the ultrasonic microphone. The partial discharge monitoring device is operable to detect failures of the substation components, especially transformer and associated cables, by detecting 3 abnormal signal values before the actual irreversible failures and the
N resulting interruption and repair costs are realized. Moreover, the ? substation monitoring system employs other sensors to detect and > 25 monitor other parameters and condition status, such as transformer
E temperature, humidity, access control, geological location, transport 2 monitoring (using acceleration sensors), cable fault, and so forth, in the a substation for preventive maintenance thereof. Furthermore, the
N substation monitoring system effectively transmits alarms, either from cloud server or by using a substation connection, at a user device associated with a user (present in company's control room) authorized to monitor the health of the remotely located substation. Beneficially, the substation monitoring and transmission of alarms may be performed by the substation monitoring system in the presence or absence of an external electric supply using different types of communication networks.
Additional aspects, advantages, features and objects of the present disclosure would be made apparent from the drawings and the detailed description of the illustrative embodiments construed in conjunction with the appended claims that follow.
It will be appreciated that features of the present disclosure are susceptible to being combined in various combinations without departing from the scope of the present disclosure as defined by the appended claims.
BRIEF DESCRIPTION OF THE DRAWINGS
The summary above, as well as the following detailed description of illustrative embodiments, is better understood when read in conjunction with the appended drawings. For the purpose of illustrating the present disclosure, exemplary constructions of the disclosure are shown in the drawings. However, the present disclosure is not limited to specific methods and instrumentalities disclosed herein. Moreover, those skilled
A 20 in the art will understand that the drawings are not to scale. Wherever
N
S possible, like elements have been indicated by identical numbers.
O
K Embodiments of the present disclosure will now be described, by way of
I example only, with reference to the following diagrams wherein: jami 5 FIG. 1 is a schematic view of a substation monitoring system for
O a 25 monitoring a partial discharge in a substation eguipped with a
N transformer, in accordance with an embodiment of the present disclosure;
FIG.2 is a schematic view of a substation equipped with a substation monitoring system for monitoring a partial discharge in the substation, in accordance with an embodiment of the present disclosure;
FIG. 3 is a schematic view of a high frequency current transformer coil, in accordance with an embodiment of the present disclosure;
FIG.4A and 4B is a front view and a rear view, respectively, of the partial discharge monitoring device, in accordance with an embodiment of the present disclosure; and
FIG. 5 is an illustration of steps of a method for monitoring a partial discharge in a substation equipped with a transformer, in accordance with an embodiment of the present disclosure.
In the accompanying drawings, an underlined number is employed to represent an item over which the underlined number is positioned or an item to which the underlined number is adjacent. A non-underlined number relates to an item identified by a line linking the non-underlined number to the item. When a number is non-underlined and accompanied by an associated arrow, the non-underlined number is used to identify a general item at which the arrow is pointing.
DETAILED DESCRIPTION OF EMBODIMENTS
N
N 20 The following detailed description illustrates embodiments of the present 5 disclosure and ways in which they can be implemented. Although some = modes of carrying out the present disclosure have been disclosed, those
E skilled in the art would recognize that other embodiments for carrying 2 out or practising the present disclosure are also possible. &
N 25 In an aspect, an embodiment of the present disclosure provides a - substation monitoring system for monitoring a partial discharge in a substation equipped with a transformer, the substation monitoring system comprising: - a partial discharge monitoring device comprising at least one sensor that generates sensor data and at least one processor communicably coupled with the at least one sensor, wherein the at least one processor is configured to determine a partial discharge value by processing the sensor data, and wherein the at least one sensor comprises at least: - a high frequency current transformer coil configured to measure current spikes of the partial discharge, wherein the current spikes range from medium to high frequency, and - an ultrasonic microphone configured to measure pressure of sound of the partial discharge, wherein the pressure of sound ranges from low to medium frequency; and - a communication module, communicably coupled to the at least one processor and a user device, wherein the communication module is configured to transmit the partial discharge value, received from the at least one processor, to the user device, wherein the at least one processor or a processor of the user device is configured to trigger an alarm at the user device when the partial discharge value exceeds a pre-defined threshold value. 3 In another aspect, an embodiment of the present disclosure provides a
N method for monitoring a partial discharge, using a substation monitoring ? system, in a substation equipped with a transformer, the method - 25 comprising:
E - arranging at least one sensor near the transformer, wherein the at 2 least one sensor comprises a high freguency current transformer coil and a an ultrasonic microphone;
N - measuring pressure of sound, ranging from low to medium freguency, of the partial discharge in a medium-voltage section of the substation, using the ultrasonic microphone;
- measuring current spikes, ranging from medium to high frequency, of the partial discharge in a low-voltage section of the substation, using the high frequency current transformer coil; - determining a partial discharge value by processing the sensor data, using the at least one processor communicably coupled with the at least one sensor; and - transmitting, via a communication module, communicably coupled to the at least one processor and a user device, the partial discharge value, received from the at least one processor, to the user device; and - triggering an alarm, by the at least one processor or a processor of the user device, at the user device when the partial discharge value exceeds a pre-defined threshold value.
The present disclosure provides the aforementioned substation monitoring system and the aforementioned method of using said substation monitoring system for monitoring of partial discharge in substations eguipped with transformers. In this regard, the substation monitoring system comprises partial discharge monitoring device having various sensors to generate sensor data corresponding to the conditions within the substation. In particular, the partial discharge monitoring device comprises the high freguency current transformer coil and the ultrasonic microphone to determine the partial discharges from the 3 substation. Beneficially, the ultrasonic microphone and the high
N freguency current transformer coil together enable detecting a wider ? frequency range (low to medium and medium to high frequency, > 25 respectively) of the partial discharge as compared to conventional
E systems that employ any one of the electric measurements and the 2 acoustic measurement methods. Additionally, combined measurement
A with the high freguency current transformer coil and the ultrasonic
N microphone enables more detailed analysis and thus improves the detection of insulation failures. Moreover, the high freguency current transformer coil is arranged at the base of the transformer to detect partial discharges, optionally, the high frequency current transformer coil may also be connected with a plurality of cables, such as a medium voltage cable, if it is suspected of producing partial discharges, to monitor possible partial discharges inside the insulation of the suspected cables, thereby providing a preventive, overall monitoring of the substation.
Furthermore, the communication module of the substation monitoring system relays sensor data analysed by the at least one processor to the user device. Furthermore, the substation monitoring system is configured to trigger an alarm at the user device to prevent from an irreparable loss resulting from partial discharges and other conditions of the substation.
Throughout the present disclosure the term "substation" as used herein refers to an electrical system, with a low- to high-voltage capacity, comprising a set of equipment involved in electrical generation, transmission, and distribution system. The substation typically converts alternating current (AC) to direct current (DC), transforms electrical power of high voltage to low voltage (stepping down) or low voltage to high voltage (stepping up) for transmission through distribution grids, or perform several other functions. Moreover, several substations may be employed at different voltage levels between a generating station and an end user to enable the electricity distribution applications. In this regard, the substation may include several components such as a transformer, a 3 disconnector, a cable, and so forth to change voltage levels between high
N transmission voltages and lower distribution voltages, or at the ? interconnection of two different transmission voltages.
E 25 Optionally, the substation is any of a primary substation or a secondary substation. In this regard, the primary substation provides an 3 interconnection between a high voltage and a medium voltage. Notably.
O the primary substation is used to transfer electrical power from the network transmission lines to the distribution line of an area. In an example, the voltage may be reduced to a correct level suitable for local distribution from medium voltage (up to 36 kV) to low voltage (up to 0.9 kV). Optionally, the primary substation may be linked with bulk load centres alongside primary lines of transmissions. Optionally, the voltages are stepped-down at various voltage ranges for purpose of secondary transmission. The secondary substation provides an interconnection between medium and low voltage. Moreover, the secondary substation may be lined alongside secondary transmission lines adjacent to loads.
Furthermore, the voltages here are further stepped-down for purpose of distribution.
Moreover, the substations may be classified on the basis of any one of: a voltage level, an application within a power system, a method used to insulate most connections, materials of the structures used, and so on.
In an example, the substation may be a transmission substation, a distribution substation, a collector substation, and so forth. Furthermore, the substation may be located on the surface in fenced enclosures, underground, or in special-purpose buildings such as a high-rise building with several indoor substations. It will be appreciated that the indoor substations are used to protect various components, such as switchgears, from extreme climate conditions or pollution. Additionally, a grounding (earthing) system may be designed to protect a passer-by during a short circuit in the transmission system. Furthermore, a compact substation is 3 built in a metal enclosure, in which each item of the electrical equipment
N is located very near to each other to create a relatively compact size of ? the substation.
E 25 The term “transformer” as used herein refers to a passive component that transfers electrical energy from one electrical circuit to another 3 circuit, or multiple circuits. The transformer works on the principle of
O Faraday's law of electromagnetic induction and mutual induction. In this regard, a varying current in one coil of the transformer produces a varying magnetic flux in the transformer's core, that induces a varying electromotive force across other coils wound around the same core for regulating the voltage. The transformer may be a step-up transformer that increases low alternating current voltages at high current, or a step- down transformer that decreases high alternating current voltages at low current in electric power applications. The transformers may range in size from RF transformers (less than a cubic centimetre in volume) to units weighing hundreds of tons used to interconnect the power grid. The transformer comprises several components such as core, windings, insulation, bushings, and so forth. However, the insulation may produce current spikes, referred to as a partial discharge, resulting in a potential failure of the transformer.
The term “partial discharge" as used herein refers to a small electrical current spark or spikes that occur in high voltage electrical insulation whenever there are small air gaps or voids in or on the surface of the insulation. More specifically, partial discharge is an electrical discharge that occurs across a localized area of the insulation between two conducting electrodes, without completely bridging the gap. In this regard, the partial discharge usually takes place inside or on surface of a medium voltage component. The partial discharge is considered as an indication of weak spots in the insulation that can cause failure. The partial discharge may be detected by field testing while on site, or 3 continuously monitored over time on-line, either on a temporary or
N permanent basis, to efficiently plan maintenance and prevent failure.
O
It will be appreciated that to reduce the complexity of distribution
E 25 networks, increase coordination during an emergency, and reduce operating costs, the substations are provided with automated supervision 3 and control from a centrally attended point. In this regard, the
O substations are eguipped with monitoring systems such as the substation monitoring system as disclosed in the present disclosure. The substation monitoring system is configured to measure the partial discharge in the substation and provide a preventive maintenance of the substation. The novel substation monitoring system of the present disclosure can be employed to efficiently monitor a remotely located substation in real-time to prevent irreversible losses. Additionally, the disclosed substation monitoring system is a standalone equipment that centrally calculates information from a large amount of data received from sensors to monitor actual conditions of the substation and predict the need for maintenance thereof in real-time.
Pursuant to the embodiments of the present disclosure, the substation monitoring system for monitoring a partial discharge in a substation equipped with a transformer comprises a partial discharge monitoring device comprising at least one sensor that generates sensor data and at least one processor communicably coupled with the at least one sensor, wherein the at least one processor is configured to determine a partial discharge value by processing the sensor data. The term "partial discharge monitoring device" as used herein refers to a device having several sensors for monitoring high voltage electrical equipment.
Typically, the high voltage electrical equipment may be transformers, rotating machines, motors, cables, and so forth. Moreover, the device unit is compact, portable and light weight in a range from 250 to 400 gram), and has dimensions in a range from 50 mm x 90 mm x 30 mm 3 (width, height, depth) to 150 mm x 200 mm x 60 mm. In an example,
N the partial discharge monitoring device that has dimensions 100 mm x ? 180 mm x 45 mm weighs 330 gm. The disclosed partial discharge > 25 monitoring device is designed for long term data recording, alarm
E handling, event recognition, remote sensing, and so forth.
N
O
3 The partial discharge monitoring device consists of a router and a sensor
O board, comprising at least one sensor, permanently connected thereto.
The router is controlled by an ESP 32 processor. The communication connections are implemented with an integrated modem circuit, which is connected to a telephone (such as a mobile phone or a landline) network via an LTE-M connection. The partial discharge monitoring device may also support an NB-IoT and a 2G technology. In this regard, a SIM card is pre-installed on the partial discharge monitoring device. The sensor board may have its own processor that reads the at least one sensor and maintains the sensor data that the router reads and transmits to a backend system (namely, a user device) over a secure connection as
MQTT messages. An X.509 certificate is installed on the router for encryption. Notably, the X. 509 certificate is a digital certificate based on the widely accepted International Telecommunications Union (ITU) X. 509 standard, which defines the format of public key infrastructure (PKI) certificates. the X. 509 certificate is used to manage identity and security in internet communications and computer networking.
Optionally, the partial discharge monitoring device operates on a 24V DC or on its own internal battery. Once the supply voltage has been disconnected, the partial discharge monitoring device can be switched off completely or started on the battery. It will be appreciated that the partial discharge monitoring device cannot be switched off without disconnecting the external operating voltage, herein the internal battery acts as a backup power source during power outages and enables transport and monitoring of partial discharge at site.
N
The term ”at least one sensor” as used herein refers to a sensor that 5 detects an event or a change in environment in the vicinity of the sensor ~ and send the information (namely, sensor data) to other electronic
E 25 components, such as a processor, for further processing and analysis thereof. The at least one sensor is the high freguency current transformer 3 and the ultrasonic microphone that function together to measure the
O partial discharge. Beneficially, the combined measurement with the high freguency current transformer and the ultrasonic microphone enables more detailed analysis of sources of partial discharge and thus improves the detection of insulation failures. The term "at least one processor" as used herein refers to an integrated electronic circuit that performs the calculations such as basic arithmetic, logic, controlling, input/output operations, and the like, specified by the instructions in a computer program. Moreover, the at least one processor is communicably coupled with the at least one sensor to determine a partial discharge value by processing the sensor data.
The term "high frequency current transformer coil” (HFCT coil) as used herein refers to a sensor having an induction coil with a ferromagnetic core suitable for the measurement of transient signals as the partial discharge or pulse-shaped noise interferences. Moreover, the HFCT coil is configured to measure current spikes of the partial discharge ranging from medium to high frequency. In general, when on-line current spikes of the partial discharge measurement are performed on high voltage electrical equipment, the HFCT coil is clamped to the transformer's ground conductor. Notably, the HFCT coil is more sensitive than acoustic measurement and may be used to monitor all substation's components.
Typically, the HFCT coil converts the current (as a result of the partial discharge spikes) flowing therethrough HFCT coil into a corresponding induced voltage spikes that is measured over an input impedance of the
HFCT coil.
N
Optionally, the high frequency current transformer coil measures the 5 partial discharge in a frequency range of 100kHz to 2MHz. The HFCT coil ~ may capture the partial discharge in a frequency range from 100kHz,
E 25 200kHz, 400kHz, 800kHz, 1.0MHz, 1.2MHz, 1.4MHz, 1.6MHz or 1.8MHz
J up to 200kHz, 400kHz, 600kHz, 800kHz, 1.0MHz, 1.2MHz, 1.4MHz, 3 1.6MHz, 1.8MHz or 2MHz. It will be appreciated that the HFCT coil
O provides high sensitivity irrespective of the source or location of the partial discharge in the transformer. In an example, the HFCT coil may be located close to or far from the partial discharge source and the measurement of the current spikes of the partial discharge with a common time reference allows the determination of the location of defects by the time-of-flight analysis. In this regard, the current spikes of the partial discharge waveform may be recorded for post processing purposes. The recorded signals may be classified by the characterization of the partial discharge waveform to discriminate different current spikes of the partial discharge or noise sources. The said analysis of the associated different current spikes of the partial discharge patterns, improves the sensibility in the detection of defects and facilitates more accurate monitoring of the high voltage electrical equipment.
The term "ultrasonic microphone" as used herein refers to an acoustic sensor that measure pressure of sound (ultrasound) of the partial discharge in a high voltage electrical equipment, ranging from low to medium frequency. Moreover, the ultrasonic microphone sensitivity is a measure of the electrical output of the ultrasonic microphone (volts) given a known sound pressure at a known frequency. Optionally, the ultrasonic microphone measures the pressure of sound in a frequency range of as low as 20 kHz to 60 kHz. The pressure of sound generated in surface discharges and detected by the ultrasonic microphone may for example be in the frequency range from 20 kHz, 25kHz, 30kHz, 35Khz, kHz, 45kHz, 50kHz or 55kHz up to 25kHz, 30Khz, 35Khz, 40 kHz,
N 45kHz, 50kHz, 55kHz or 60 kHz.
S
S Optionally, the at least one sensor further comprises at least one of: - a temperature sensor, arranged in a medium-voltage section of the
E 25 substation, for measuring a temperature of the substation, wherein the temperature sensor is a far-infrared sensor; 3 - a humidity sensor, arranged in a medium-voltage section of the
O substation, for measuring a humidity of the substation.
In this regard, optionally, the technical condition of the main components of the substation, e.g., transformers, disconnectors and cable terminals, and the condition status of the substation, such as temperature, humidity, power transport speed, and access control, may be monitored remotely via various sensors of the substation monitoring system. The temperature sensor measures the temperature of its environment (i.e. the substation) and records or signals the temperature changes in the environment for further analysis. Optionally, the temperature sensor is installed at a distance ranging from 30 to 50 cm from the transformer.
Optionally, an opening angle of the temperature sensor is 50 degrees.
The term "opening angle" as used herein refers to the angle range that a sensor is capable of detecting.
Optionally, the temperature sensor may be a far-infrared sensor. The term “far-infrared sensor” as used herein refers to a sensor that measures the temperature in a far infrared (FIR) region in the infrared spectrum of electromagnetic radiation. The far-infrared sensor measures surface temperature using far-infrared measurement technology.
Optionally, the far-infrared sensor is also related to a multimeter suitable for providing the ability to measure and indicate the output as current, voltage, resistance, and impedance. The far infrared sensor may have a wavelength of 15 micrometers (um) to 1 mm (corresponding to a range 3 of about 20 THz to 300 GHz). The FIR sensor also reports its own internal
N temperature. The far infrared sensor may be small size, cost effective ? and possess high thermal stability. Beneficially, the use of the far infrared > 25 sensor results in reduction in cost, measurement time and complexity of
E the system.
O
3 The humidity sensor typically detects and measures changes in humidity
O in the air present inside the high voltage electrical eguipment that alters electrical currents or temperature therein. The humidity sensor is operable to monitor minute changes in the air in order to calculate the humidity in the air. The humidity sensors may be a capacitive, a resistive or a thermal humidity sensor.
Optionally, the at least one sensor may further comprise an acceleration sensor for measuring a power transport to and from the substation.
Typically, the acceleration sensor measures vibration, or acceleration of components, such as a stator end winding, inside the high voltage electrical equipment. Specifically, the acceleration sensor is operable to detect and convert acceleration into measurable quantities such as electrical signals. Optionally, the acceleration sensor are arranged at locations that are most likely to vibrate. Optionally, the acceleration sensor may be used to understand stability of the substation owing to their ability to monitor any unwanted forces or vibrations in the substation. Optionally, the acceleration sensor may be a piezoelectric acceleration sensor. Optionally, a tri-axial acceleration sensor may be used to provide the sensor data by collecting data in 3 directions simultaneously. Optionally, the acceleration sensor may be mounted using a stud or cement mounting to achieve the measured value closer to a calibrated value.
Moreover, the acceleration sensor may also monitor bumps. Normally, bumps are reported when the acceleration limit that may be set remotely
N (via the user interface) exceeds. Therefore, when the limit value is
O exceeded, the instantaneous maximum value of the acceleration is stored 5 and the maximum acceleration value of the reporting interval is reported ~ by the substation monitoring system. Notably, the frequency range of the
E 25 acceleration sensor is governed by the natural freguency of the sensor itself. Optionally, the acceleration sensor typically has the natural 3 frequency in the 5-10 kHz.
QA
N
Optionally, the at least one sensor may further comprise a location sensor for tracking geological location and positioning of the substation. In this regard, the location sensor may communicate with a global positioning satellite receiver (GPS) of the substation. Optionally, the location sensor may also work with a communication interface or network and/or WIFI location services. Optionally, the location may be the substation's present latitude and longitude, or the substation's address. Normally, the measuring units employed in the location sensor for distance is in meters and time is measured in milliseconds (ms). Furthermore, the locations of substations may be preset in the GPS.
Optionally, the at least one sensor is temperature compensated. The term "temperature compensated” as used herein refers to the temperature limits of operation of the at least one sensor, such as the sensors configured to measure the partial discharge) for which said at least one sensor meets the stated measurement accuracy thereof. Moreover, the temperature compensation refers to a measure for counteracting or correcting an undesired temperature influence on a measured value. In other words, temperature compensation is a method used to enhance performance of the at least one sensor to compensate for effects caused by changes in temperature. Beneficially, the at least one sensor is temperature compensated to dynamically adjust the voltage depending on the ambient temperature, thereby achieving prolong life thereof and accuracy in detecting the partial discharge. Additionally, the temperature compensated sensors may provide high precision under different complex 3 environment conditions of substation requirements. In an example, the
N temperature compensated ultrasonic microphone is not influenced by the ? temperature inside the high voltage electrical equipment, thereby > 25 resisting the temperature to cause significant impact on the ultrasound
E time-of-flight that may distort the calculated distance value of the 2 measured sound. Optionally, the at least one sensor is temperature
A compensated at a range between -20 to +40 °C. The compensated
N temperature range may be for example from -20, -10, 0, +10, +20 or +30 ?C up to -10, O, +10, +20, +30 or +40 °C.
Optionally, each of the at least one sensor is connected to an I2C port of the substation monitoring system via an I2C splitter. The term "I2C port” (namely, Inter-Integrated Circuit port or connector) as used herein refers to a synchronous, multi-master, multi-slave, packet switched, single- ended, and a serial communication bus. In this regard, the I2C port may be used for attaching lower-speed peripheral such as ICs to the processors and microcontrollers in short-distance, intra-board communication. Optionally, the I2C may use bidirectional open-collector or open-drain lines such as serial data line (SDA) and serial clock line (SCL), pulled up with resistors. The I2C port could be connected via two parallel Ethernet interfaces, and a CATS cable, having a maximum length of for example 10 meters, may be used for cabling. Moreover, up to 8
I2C splitters may be connected to the I2C port, to which the at least one sensor (I2C sensors) are connected. It will be appreciated that, a unique
I2C address is set for each I2C splitter using three dip switches inside housing of the partial discharge monitoring device. Moreover, the I2C port terminates at the last I2C splitter arranged in the cable line with a short circuit block. Furthermore, by default, splitters are set so that the cable line ends at the first I2C splitter. The term "I2C splitter” as used herein refers to a device that allows the connection of more I2C devices by sharing the same I2C port. Optionally, the I2C splitter may have components such as header pin holes, DF13 connectors, and JST-GH 3 connectors for abundant compatibility with different devices. = Furthermore, it is possible to continue the balanced I2C port by daisy- m 25 chaining the I2C Splitters. The daisy chain is typically a wiring scheme
I in which multiple devices are wired together in sequence or in a ring.
N Optionally, a differential driver may be used as an alternate version of 2 I2C port to communicate up to 20 meters (possibly over 100 meters)
S over a plurality of cables, such as over CAT5 or any other cable.
Optionally, the CAT5 cable may be used for Ethernet physical layer to carry differential-encoded I2C signals or boosted single-ended I2C signals.
Optionally, the sensor data is generated continuously or intermittently.
In this regard, at least one sensor such as the HFCT, the ultrasonic microphone, the temperature sensor, the humidity sensor, and others collect respective sensor data in real-time continuously or at pre-defined time intervals of equal or different intervals. In an example, the sensor data is generated every second. In another example, the sensor data is generated every 5 min.
Optionally, the sensor data is generated at 2-second intervals, and a 400 ms peak is sampled from the sensor data. As mentioned before, the HFCT coil and the ultrasonic microphone work in conjunction with each other and generate the sensor data at 2 second intervals. In this regard, the
HFCT coil captures the cable interferences and converts the signals into voltage spikes and the ultrasonic microphone measures the pressure of sound generated in surface discharges at every 2 seconds. Moreover, a 400 ms peak is sampled from the sensor data generated at every 2 second. It will be appreciated that the peak values are calculated and reported to a remote condition monitoring system for the average and maximum over the system reporting interval (such as 10 minutes).
N Moreover, the substation monitoring system comprises a communication = module, communicably coupled to the at least one processor and a user 7 device, wherein the communication module is configured to transmit the - partial discharge value, received from the at least one processor, to the
E 25 user device. 3
O The term "communication module" as used herein refers to a module that
ES enables the exchange of messages between different devices installed in the system. Moreover, the communication module could be a GPS, an
IoT, a GPS, an LTE-M and/or a CDMA sim card installed in the partial discharge monitoring device and the substation monitoring system, and optionally the user device. Optionally, the communication connections may be implemented with an integrated modem circuit, that is connected to the mobile telephone network via an LTE-M connection. Optionally, the hardware may also support an NB-IoT and a 2G technology. Optionally, the SIM card is pre-installed on the device. In this regard, the substation monitoring system employs the communication module communicably coupled to the at least one processor thereof as well as the processor of the user device. Thus, transmitting the partial discharge value, received from the at least one processor, to the user device. Notably, the user device may be associated with a user, that is remotely monitoring the substation.
Moreover, the at least one processor or a processor of the user device is configured to trigger an alarm at the user device when the partial discharge value exceeds a pre-defined threshold value. In this regard, the partial discharge monitoring device employs the router, attached to the sensor board and controlled by an ESP 32 processor, to read and transmit the sensor data to the backend system (namely, a user device) over the secure connection as MQTT messages.
Optionally, triggering an alarm is implemented as a notification sent at
N the user device. In this regard, the alarm is indicative of the partial
O discharge or other failure in the system. Optionally, the alarms are 5 triggered using the cloud server or from the transformer. Optionally, the ~ alarm levels may be set on a case-by-case basis. Optionally, the alarms
E 25 may be a text message, a ring (or siren), a light flash, a voice message, and so forth. Optionally, the intensity of the alarm, specially, the light 3 flash and the ring (or siren) type alarm, to alert the operator (or the user)
O regarding the intensity of failure in the substation. In an example, for a 20% failure a 'yellow' light may flash, for a 50% failure an 'orange' light may flash, and for failures ranging above 60% a 'red' light may flash.
Optionally, the substation monitoring system employs separate door switches that may be used to monitor the status of the doors in two separate circuits, the low voltage section and the medium voltage section or side doors separately. Furthermore, the door switches may be connected to the circuit thereof in parallel, thereby enabling each of the circuit door to cause an alarm. Optionally, the circuit may be open in normal mode, thereby eliminating the need of supervision for a broken wire.
Optionally, the substation monitoring system operates on the communication module such as an Amazon Web Services (AWS) cloud service. In this regard, the IoT solutions recommended by the AWS have been used in the implementation. The AWS's IoT Core service enables receiving messages, maintaining and updating the partial discharge monitoring device status using Shadow service. In this regard, AWS's IoT
Device Shadow service adds shadows to AWS IoT objects. The shadows make available a device's state available to apps and other services whether the device is connected to AWS IoT or not. For example, a device may reguest a change in a device's state by updating the shadow and
AWS IoT may publish a message that indicates the change to the device.
Moreover, the device may receive the message, update the state to match, and publish the message with its updated state. The AWS's IoT 3 device Shadow service reflects the updated state in the corresponding
N shadow. Optionally, the data processing may be based on the serverless ? architecture, where AWS Lambda functions are called as needed. > 25 Moreover, the dimension data may be stored in the timestream time
E series database. Notably, the latest results as well as other measurement 3 metadata may be stored in the DynamoDB database.
N
I Optionally, the substation monitoring system receives power, when in use, from at least one of: an external power source, and a battery unit.
The external power source is an external circuit (outside the substation monitoring system) that converts electric current into DC current or lower-voltage AC current for operating a consumer product. The battery unit is a source of electric power, herein installed within the substation monitoring system, for powering electrical devices. Optionally, the substation monitoring system may operate on a 24V DC or on the internal battery thereof. In this regard, once the supply voltage has been disconnected, the system may be switched off completely or may be started on the battery. In other words, the substation monitoring system employs the battery unit for providing power thereto when the external power source is interrupted. Optionally, the battery unit may be a primary battery unit and a secondary battery unit. The primary battery unit is designed to be used until it is exhausted of energy then discarded as the chemical reactions in the primary batteries are not reversible. The secondary battery unit may be recharged and used again multiple times as the chemical reactions therein may be reversed by applying electric current to the cell. Optionally, the battery may be a 3000mAh battery.
Beneficially, in an event of a power failure, the substation monitoring system will continue to report sensor data to the at least one processor or information to the processor of the user device at its normal rate for 2 hours. Grid scale energy storage envisages the large-scale use of batteries to collect and store energy from the grid or a power plant and then discharge that energy at a later time to provide electricity or other 3 grid services when needed. Grid scale energy storage (either turnkey or = distributed) are important components of smart power supply grids. ~ 25 Additionally, the partial discharge monitoring device may not be switched x off without disconnecting the external operating voltage in the system. 2 Optionally, the substation monitoring system, when in operation, is in at 3 least one of: a normal operating mode; an operating mode comprising a
N standby mode and a power saving mode; and a transport monitoring mode. The terms "normal operating mode", "standby mode", "power saving mode" and "transport monitoring mode" as used herein refer to different types of operating modes of the substation monitoring system, during the monitoring and maintenance stages of the life cycle of the substation monitoring system. In this regard, the different operating modes may include starting, normal operation, shutdown, product transitions, maintenance, and so forth.
Optionally, the substation monitoring system, is ideally in the normal operating mode, i.e. on 24V DC power supply. In normal operating mode, a normal reporting interval may be for example of 10 min as set by a back-end system. The reporting interval is the transmission interval of measurements to the background system. In addition, the substation monitoring system may be used to send information to the back-end system in the form of an interruption (for example, a short delay) when switching from one operating mode to another. Moreover, other data to be sent in the interrupt type may be an external relay tip data.
Furthermore, for the measured values to be reported according to the reporting interval, a possible alarm is triggered in the back-end system, wherein the alarm limits could be defined either per substation or globally.
Optionally, the substation monitoring system may be in any of a standby mode or a power saving mode. In standby mode, the substation
N monitoring system employs the battery unit. Moreover, the standby mode
O enables the system to report the sensor data and continue monitoring at 5 a normal rate (for example, 2 hours) in the event of a power failure. ~ Normally, in an event of power failure, the information about switching
E 25 to the battery unit may be sent to the backend system, the user interface
IS of which indicates that not all measurements can be performed as the 3 operating mode has changed to standby mode. For example, the external
O relay tip data cannot be read while the operating mode is on the standby mode and no alarm can be generated at the relay output. Moreover, the ultrasonic microphone may not rely on the battery unit and the other sensor data is reported normally.
Optionally, after the standby mode of operation, the system may enter into the power saving mode, that is utilized for monitoring transport and storage of the sensor data. In this regard, the router of the substation monitoring system is activated on a timer basis (for example, every 24 hours) and the location sensor may be used to report the location to the backend system.
Optionally, the substation monitoring system may be in the transport monitoring mode. In this regard, when the acceleration sensor limit value is exceeded in the power saving mode, the crash event and GPS position at the time of monitoring may be reported within 1 hour of reporting.
Moreover, optionally, a user interface of the user device is configured to receive information about an operating mode of the substation monitoring system. The term "user interface" as used herein refers to a space to enable interactions between the user and a system, such as an equipment, a machine, a computer, a website or an application software.
In this regard, the user interface of the user device receives information about the different operating modes of the substation monitoring system.
Optionally, the user interface allows effective operation and control of the
N system from the user end, while the system simultaneously feeds back = information such as the sensor data, that aids the operators' decision- 7 making process. Optionally, the user interface enables the user's - experience easy and intuitive, reguiring minimum effort on the user's part a 25 to receive maximum desired outcome. Moreover, the user interface code
S may be executed by the user's browser and is downloaded from the AWS 3 S3 file server. In this regard, the user interface may be implemented in
N a React programming environment. Furthermore, the user interface to the backend data may be the GraphQL query language. Optionally, the user interface may use a secure https connection and an AWS Cognito user management.
Optionally, the substation comprises: - a transformer cabinet having arranged therein the transformer; - a low-voltage section having arranged therein a main earth bar and the high freguency current transformer coil arranged at a base part of the transformer, - a medium-voltage section having arranged therein a plurality of disconnector switches, the ultrasonic microphone, the temperature sensor, and the humidity sensor, wherein the low-voltage section and the medium-voltage section are on either side of the transformer cabinet; and - a plurality of cable running between the medium-voltage section and the transformer cabinet for connecting the plurality of disconnector switches to the transformer.
The term "transformer cabinet" as used herein refers to a high voltage section in the substation where the transformer is arranged. The term "low-voltage section” as used herein refers to a section having low- voltage components, such as a main earth bar and the high freguency current transformer coil arranged at a base part of the transformer. The
N term " medium-voltage section" as used herein refers to a section having
O medium voltage components, such as a plurality of disconnector 5 switches, the ultrasonic microphone, the temperature sensor, and the ~ humidity sensor, and other sensors.
I
2 25 The term "plurality of cables" as used herein refers to a group of wires
S covered in plastic or rubber insulation to carry electricity or electrical 3 signals to and from the substation monitoring system. In this regard, the
N substation monitoring system employs the plurality of cable running between the medium-voltage section and the transformer cabinet for connecting the plurality of disconnector switches to the transformer. It will be appreciated that the plurality of the disconnector switches depends on number of the medium voltage cables connected to the transformer in the high voltage section of the substation monitoring system.
Optionally, the partial discharge may take place inside or on surface of the medium voltage insulator. In this regard, the medium voltage circuit breaker is followed by at least one sensor such as the HFCT coil, the ultrasonic microphone, and so forth. When the partial discharge takes place, the ultrasonic microphone detects the pressure of sound generated by the current spikes of the partial discharge. The partial discharge also generates high frequency current on transformer cabinet earthing wires that are all connected to the main earth bar (MEB). The main earth bar is located in the low-voltage section of the substation. The main earth bar may be connected to grounding electrode and the HFCT coil enables measuring the high frequency current that flows to earth. Furthermore, since almost all grounding currents flow via the plurality of cables, all possible partial discharges inside the substation may be monitored.
Additionally, the HFCT coil may also be connected to other grounding wires such as the earthing of the medium voltage cables or the power transformer earthing when the cable or the transformer insulations are suspected. Beneficially, the said arrangement enables monitoring of the current spikes of the partial discharge inside the insulation of the medium
N voltage cables connected to the substation. '
S Optionally, the substation monitoring system further comprises a cable fault monitoring arrangement for measuring a fault in cables of a plurality
E 25 of devices. The term “cable fault monitoring arrangement” as used herein refers to an arrangement for detecting a direction of the fault in cables 3 during unwanted accidents or faults such as short circuit, open circuit,
O insulation breakdown, and so forth. An example of cable fault monitoring arrangement may be a SigmaD® or SigmaD++® (Horstmann Germany) that provides a direction of fault. Beneficially, the cable fault monitoring arrangement provides a fault detection method to recover power lines.
Optionally, the cable fault monitoring arrangement may include a plurality of resistors to represent the cable in case of underground cable fault monitoring arrangement. In this regard, a DC voltage is supplied at one end and the defect is detected by detecting the voltage variation in the buried cable. The sensor data is then fed to an AD convertor to develop precise digital data. The digital data may then be processed using the processor to show the output. Moreover, the faults occurring in the power lines and cables may be classified into four main categories such as short circuit to another conductor in the cable, short circuit to earth, high resistance to earth and open circuit.
Optionally, an automatic analysis of the reflectograms collected during the partial discharge monitoring using a method referred to as time domain reflectometry (TDR) allows the location of insulation irregularities. In the Time Domain reflectometry (TDR) method, a low energy signal is sent through the cable where the perfect cable with the uniform characteristic impedance returns the signal within a known time and with a known profile. The time and profile of the signal is altered once the cable has impedance variation due to any fault. The impedance variation causes a portion of the signal reflected back to source. The reflected signal fortifies the original signal when there is an increase in 3 characteristic impedance at the fault location, while it opposes the
N original signal when there is a decrease in characteristic impedance. ? Furthermore, a graphical representation on the Time Domain > 25 Reflectometry (TDR) screen gives the user the distance to the fault in
E time units. Optionally, a four-relay data from each of the five external 2 devices (such as Horstman Sigma D++ ®) may be imported into the
A system to provide additional earth fault detection methods for
N compensated and isolated neutral networks. Optionally, the four-relay data module may contain four 5V relays and the associated switching and isolating components, that makes interfacing with a microcontroller or sensor easy with minimum components and connections. Optionally, the
Sigma D series may be combined directional short-circuit and directional earth fault indicators for medium voltage distribution networks. In this regard, the relays are switches to open and close circuits electromechanically or electronically. The relays control one electrical circuit by opening and closing contacts in another circuit. Optionally, the relay may consist of a set of input terminals for a single or multiple control signals, and a set of operating contact terminals. Optionally, the high- voltage electrical equipment may be controlled with small, low voltage wiring and pilot relay switches. Moreover, voltage is applied to each line in the device to read the relay data. Optionally, the devices may be current sensor powered. Optionally, each device may comprise a common ground or return line.
Optionally, the relay data may be an alarm data that may be configured on the partial discharge monitoring device unit for two digital outputs from which an external device, such as the substation in the transformer, may read the alarm data. Optionally, the implementation is done with a channel transistor (FET), that connects the 24V supply voltage to the output. No voltage is applied separately to the partial monitoring device to read the relay. Optionally, the ground (GND) of the hardware is connected to the ground of the external substation's input/output
S module.
S Optionally, the substation monitoring system further comprises a memory module for storing a plurality of the partial discharge values and
E 25 the pre-defined threshold value. The term "memory module" as used herein refers to a device or a system that is used to store information for 3 immediate use in a hardware, software, electronic devices, and the like.
O Optionally the memory may be an in-built memory of the system (such as read-only memory (ROM), random access memory (RAM), and the like) or a memory on a remote server. In another embodiment, the memory module may be a secondary memory, such as hard disk drives, secondary storage disks, floppy disks and the like. In this regard, the memory module is used for storing a plurality of the partial discharge values and the pre-defined threshold in the substation monitoring system. Moreover, the memory module is configured to store all the sensor data collected from at least one sensor such as the temperature sensor, the humidity sensor, the location sensor, the acceleration sensor, as well as different operative mode time intervals, instructions and values received by the user device, and so forth. Furthermore, the memory module may work in conjunction with the communication module and an alarm to process the sensor data.
Optionally, the substation monitoring system may comprise a short circuit piece and a dip switch. The term "short circuit piece" as used herein refers to an electrical circuit that allows a current to travel along an unintended path with no or low electrical impedance, thereby resulting in an excessive current flowing through the circuit. In other words, the short circuit piece is an abnormal connection between two nodes of an electric circuit intended to be at different voltages. Beneficially, the short circuit piece results in an electric current limited only by the Thevenin equivalent resistance of the rest of the network which can cause circuit damage, overheating, fire or explosion. With a low resistance in the connection, a
N high current will flow, causing the delivery of a large amount of energy
N in a short period of time. In electrical devices, unintentional short circuits ? are usually caused when a wire's insulation breaks down, or when another > 25 conducting material is introduced, allowing charge to flow along a
E different path than the one intended. Furthermore, to reduce the negative 2 effects of short circuits, power distribution transformers are deliberately
A designed to have a certain amount of leakage reactance. The leakage
N reactance (of usually about 5 to 10% of the full load impedance) helps limit both the magnitude and rate of rise of the fault current. Additionally, the substation monitoring system employs the short circuit piece to continue forward the I2C port. Moreover, when the I2C divider is the last in the line, the short circuit piece enables short circuiting of both rows of terminals.
Optionally, the substation monitoring system may comprise a dip switch.
The term "dip switch" as used herein refers to a manual electric switch that is packaged with others in a group in a standard dual in-line package (DIP). The term dip switch may refer to each individual switch, or to the unit as a whole. Moreover, the dip switch is used on a printed circuit board along with other electronic components to customize the behaviour of an electronic device for specific situations. Beneficially, the DIP switches are guicker to change and contain no parts to lose. The DIP switches may be classified as the slide, rocker, piano (side), rotary, and so forth. It will be appreciated that the dip switch may be used to provide a separate address for each divider in the system. Moreover, the least significant bit of the dip switch may be at the farthest edge from the Ethernet connector. For example, when I2C dividers are daisy-chained to several separator units for IR matrices, the I2C addresses may be defined in ascending numerical order, in the same order in which the separators are also numbered.
Optionally, the substation monitoring system further comprises
N monitoring a partial discharge in a switchgear, coupled to the
O transformer, that is configured to interrupt fault currents flowing between 5 circuits, wherein the switchgear includes switches, disconnector switches, ~ fuses and light arrestors. The term "switchgear" as used herein refers to
E 25 electrical disconnect switches, used to control, protect and isolate electrical equipment. Optionally, the switchgear may be used both to de- 3 energize equipment to allow work to be done and to clear faults
O downstream. Typically, the switchgear in the substation may be located on both the high- and low-voltage section of the transformers.
Beneficially, the switchgear may be used to enhance system availability by allowing more than one source to feed a load.
Optionally, the partial discharge monitoring device further comprises: - an amplifier for amplifying at least one of a current and a voltage; - a peak detector for measuring the highest partial discharge value; - an AD converter for converting the partial discharge value into a digital signal.
In this regard, the amplifier (a two-port electronic circuit) uses electric power from a power supply to increase the amplitude of a signal applied to its input terminals, producing a proportionally greater amplitude signal at its output. Beneficially, the amplifier amplifies at least one of a current and a voltage. In this regard, the amount of amplification provided by the amplifier is measured by a parameter called gain of the amplifier. The gain is the ratio of output voltage, current, or power to input. Optionally, the amplifier may either be a separate piece of equipment or an electrical circuit contained within another device. Moreover, the amplifiers may be categorized in different ways based on frequency of the electronic signal being amplified such as an audio amplifier, a RF amplifier, a servo amplifier, an instrumentation amplifier, and so forth. For example, the audio amplifiers amplify signals in the audio (sound) range of less than
N 20 kHz, the RF amplifiers amplify freguencies in the radio freguency range
O between 20 kHz and 300 GHz; the freguency may be for example from 5 20 servo amplifiers and the instrumentation amplifiers may function ~ under low frequencies down to direct current.
I
2 25 The peak detector may be a series connection of a diode and a capacitor
S outputting a direct current voltage egual to the peak value of the applied 3 alternating signal of the partial discharge. Optionally, the test voltage
N may be displayed in sinusoidal waveform. Typically, the AD convertor (namely, analog-to-digital converter, ADC, A/D, or A-to-D) may work in conjunction with the ultrasonic microphone of the system to convert analog signals, such as a sound picked up by the ultrasonic microphone or the partial discharge detected by the ultrasonic microphone, into the digital signal. Optionally, the AD convertor may work in conjunction with the amplifier and at least one sensor such as the temperature sensor, the humidity sensor, and so forth in the system to produce the analog signal of parameters such as temperature, humidity, and so forth, wherein the analog signals from a given sensor may be amplified and fed to the AD convertor to produce the digital signal proportional to the input signal.
Furthermore, the AD convertor enables periodical conversion, sampling of the input signal, and limiting the allowable bandwidth of the input signal. The performance of the AD convertor may be characterized by the bandwidth and signal-to-noise ratio (SNR) thereof. The bandwidth of the
AD convertor is characterized by sampling rate. The SNR of the AD convertor is influenced by factors such as the resolution, linearity and accuracy (for example, how well the quantization levels match the true analog signal), and so forth. Typically, the digital output may be a two's complement binary number that is proportional to the input. Moreover, due to the complexity and the need for precisely matched components, the AD convertors may be implemented as integrated circuits (ICs).
Optionally, the said AD convertors take the form of metal-oxide- semiconductor (MOS) or mixed-signal integrated circuit chips that
W integrate both analog and digital circuits.
O
N Optionally, the substation monitoring system may comprise an analyzer ? for plotting the sensor data against corresponding phase voltage. The > 25 analyzer is typically used to analyze the sensor data and find patterns
E and relationships. Optionally, the analyzer may be a piece of hardware or 2 a software. Optionally, the autoanalyzer may be used to perform the work 3 with little human involvement. Optionally, the analyzer may work in
N conjunction with the ultrasonic microphone and the HFCT coil to analyze the frequency and the time domain sensor data. The optimum frequency may be selected, and the partial discharge signals may be compared according to frequency. Optionally, the analyzer also enables a time domain analysis of the system. In this regard, the pulse wave forms of the partial discharge signals may be obtained, and the features may be analyzed. Specifically, the analyzer plots the current spikes of the partial discharge against the corresponding phase voltage to deduce the type of discharge from the phasing. The said analysis requires high speed sampling and broadband signal processing. The measurement of the pulse level with the HFCT coil in the frequency range 100 kHz to 1 MHz may suffice to detect a partial discharge alone, but the measuring range used according to IEC 60270 is as follows: 30 kHz < f1 < 100 kHz lower limit frequencies; f2 < 1 MHz upper limit frequencies; 100 kHz < Af < 900 kHz total bandwidth. Therefore, the analyser is required to work in conjunction with the ultrasonic microphone to cover a wider range of frequency. Moreover, the analyzer also enables the estimation of the location of the partial discharge signals. In an example, the partial discharge is accompanied by the electric pulse, ultrasonic wave, electromagnetic radiation, light, chemical reaction and causing the localized heating phenomenon. In response to such issues, the partial discharge monitoring device uses the balanced and quantitative methods of the gain in the different frequency bands to sample the ultrasonic signals of the partial discharge. The equalization method is used to adjust the gains of the electronic amplifier and the acquisition system, so that 3 the ratio of the output amplitude and the input amplitude is constant in = the required spectrum. Moreover, the analog digitals after the m 25 complementary processing are converted with the highly-resolution AD x converter and processing circuits, then are inputted to the analyzer for
N analysis and processing, thereby to improve the accuracy of the partial 2 discharge monitoring device.
O
N The present disclosure also relates to the method as described above.
Various embodiments and variants disclosed above apply mutatis mutandis to the method.
Pursuant to the embodiments of the present disclosure, the method for monitoring a partial discharge, using a substation monitoring system, in a substation equipped with a transformer, comprises: - arranging at least one sensor near the transformer, wherein the at least one sensor comprises a high frequency current transformer coil and an ultrasonic microphone; - measuring pressure of sound, ranging from low to medium frequency, of the partial discharge in a medium-voltage section of the substation, using the ultrasonic microphone; - measuring current spikes, ranging from medium to high freguency, of the partial discharge in a low-voltage section of the substation, using the high freguency current transformer coil; - determining a partial discharge value by processing the sensor data, using the at least one processor communicably coupled with the at least one sensor; and - transmitting, via a communication module, communicably coupled to the at least one processor and a user device, the partial discharge value, received from the at least one processor, to the user device; and - triggering an alarm, by the at least one processor or a processor of the user device, at the user device when the partial discharge value exceeds a pre-defined threshold value.
N According to an embodiment of the present disclosure, the HFCT coil is
N arranged at a base part of the transformer in a low-voltage section of the ? substation while the ultrasonic microphone is arranged in the medium- > 25 voltage section of the substation. It will be appreciated by a person skilled
E in the art that the HFCT coil may be arranged near other components of 2 the substation, such as the cables for example medium-voltage cables, 3 for measuring a partial discharge inside or on their surface.
N
DETAILED DESCRIPTION OF THE DRAWINGS
Referring to FIG. 1, illustrated is a schematic view of a substation monitoring system 100 for monitoring a partial discharge in a substation (such as a substation 200 of FIG. 2 below) equipped with a transformer (such as a transformer 202 of FIG. 2 below), in accordance with an embodiment of the present disclosure. The substation monitoring system 100 comprises a partial discharge monitoring device 102. The partial discharge monitoring device 102 comprises at least one sensor that generates sensor data and at least one processor communicably coupled with the at least one sensor, wherein the at least one processor is configured to determine a partial discharge value by processing the sensor data, and wherein the at least one sensor comprises at least a high frequency current transformer coil 104 configured to measure current spikes of the partial discharge, wherein the current spikes range from medium to high frequency, and an ultrasonic microphone 106 configured to measure pressure of sound of the partial discharge, wherein the pressure of sound ranges from low to medium frequency. Moreover, the substation monitoring system 100 comprises a communication module, communicably coupled to the at least one processor and a user device, wherein the communication module is configured to transmit the partial discharge value, received from the at least one processor, to the 3 user device. The at least one processor or a processor of the user device
N is configured to trigger an alarm 108 at the user device when the partial ? discharge value exceeds a pre-defined threshold value.
E 25 Additionally, the substation monitoring system further comprises a cable fault monitoring arrangement 110 for measuring a fault in cables of a 3 plurality of devices. Furthermore, the substation monitoring system 100
O further comprises a temperature sensor 112 and a humidity sensor 114.
The temperature sensor 112 is a far-infrared sensor. Additionally, each of the at least one sensor in the substation monitoring system 100 is connected to an I2C port of the substation monitoring system 100 via an
I2C splitter 116. Furthermore, the system comprises a location sensor (such as a GPS antenna) 118 for tracking geological location and positioning of the substation. The substation monitoring system also comprises a battery unit120, implemented as an AC-DC adapter, for providing power thereto, when in use.
Referring to FIG.2, illustrated is a schematic view of a substation 200 eguipped with a substation monitoring system for monitoring a partial discharge in the substation 200, in accordance with an embodiment of the present disclosure. The substation 200 comprises a transformer cabinet 212, a low-voltage section 214, a medium-voltage section 216, and a plurality of cables (not shown). Moreover, the transformer cabinet 212 has arranged therein the transformer 202, the low-voltage section 214 has arranged therein a main earth bar 204 and the high freguency current transformer (HFCT) coil 206 arranged at a base 222 part of the transformer 202. The medium-voltage section 216 has arranged therein a plurality of disconnector switches, such as the disconnector switch 218, the ultrasonic microphone 208, and wherein the low-voltage section 214 and the medium-voltage section 216 are on either side of the transformer cabinet 212. Additionally, the substation 200 comprises the plurality of cable running between the medium-voltage section 216 and the 3 transformer cabinet 212 for connecting the plurality of disconnector
N switches, such as the disconnector switch 218, to the transformer 202. ? The substation monitoring system further comprises at least one of a > 25 temperature sensor 210, arranged in a medium-voltage section 216 of
E the substation 200, for measuring a temperature of the substation 200 2 and a humidity sensor 220, arranged in a medium-voltage section 216
A of the substation 200, for measuring a humidity of the substation 200.
N Furthermore, the substation 200 may further be eguipped with an acceleration sensor (not shown) for measuring a power transport to and from the substation 200; and a location sensor (not shown) for tracking geological location and positioning of the substation 200.
Herein, the partial discharge may take place inside or on surface of the disconnector switch 218 in the medium-voltage section 216 of the substation 200. The suspected disconnector switch 218 in the medium- voltage section 216 is followed by at least one sensor, such as the ultrasonic microphone 208. When partial discharge takes place the ultrasound microphone 208 detects the pressure of sound generated by the partial discharge. Moreover, the partial discharge further generates a high frequency current on the transformer cabinet 212 earthing wires which are all connected to the main earth bar 204 located in the low- voltage section 214. The main earth bar 204 is connected to a grounding electrode and the HFCT coil 206 that measures the high frequency current which flows to earth.
It may be appreciated by a person skilled in the art that aforementioned is one way of monitoring the partial discharge. However, other modes of arranging the sensors are possible to measure the partial discharge.
Optionally, HFCT coil 206 can also be connected to other grounding wires like earthing of medium-voltage cables or transformer earthing if cable or transformer insulations are suspected. In this way it is possible also to
N monitor possible partial discharges inside the insulation of medium-
O voltage cables connected to the substation 200. ? Referring to FIG. 3, illustrated is a schematic view of a high frequency - current transformer coil 300, in accordance with an embodiment of the , 25 present disclosure. The high freguency current transformer coil 300 is
S configured to measure current spikes of the partial discharge, wherein 3 the current spikes range from medium to high frequency. The high
N freguency current transformer coil 300 is typically arranged at a base part of the transformer.
Referring to FIGs. 4A and 4B, illustrated are a front view and a rear view, respectively, of the partial discharge monitoring device 400, in accordance with an embodiment of the present disclosure. As shown in
FIG.4A, the front view of the partial discharge monitoring device 400 comprises an I2C port, connected via two parallel Ethernet interfaces 402 for inserting I2C splitters therein. Moreover, the partial discharge monitoring device 400 comprises terminal blocks 404 for inserting other connectors, such as a power source 406, a low voltage door 408 and a medium voltage door 410, and an alarm 412. Additionally, the partial discharge monitoring device 400 comprises SMA connectors 414 for connecting an HFCT coil 416, an ultrasonic microphone 418, a location sensor antenna 420, and a communication antenna 422.
As shown in FIG.4B, the rear view of the partial discharge monitoring device 400 comprises terminal blocks 424 for connecting a plurality of cable fault monitoring system.
Referring to FIG.5, there is shown a flowchart 500 illustrating steps of a method for monitoring a partial discharge in a substation equipped with a transformer, in accordance with an embodiment of the present disclosure. At step 502, at least one sensor near the transformer is arranged, wherein the at least one sensor comprises a high frequency
N current transformer coil and an ultrasonic microphone. At step 504,
O pressure of sound is measured, ranging from low to medium freguency, 5 of the partial discharge in a medium-voltage section of the substation, ~ using the ultrasonic microphone. At step 506, current spikes are
E 25 measured, ranging from medium to high freguency, of the partial discharge in a low-voltage section of the substation, using the high 3 frequency current transformer coil. At step 508, a partial discharge value
O by processing the sensor data is determined, using the at least one processor communicably coupled with the at least one sensor. At step 510, the partial discharge value, received from the at least one processor, is transmitted, via a communication module, communicably coupled to the at least one processor and a user device, to the user device. At step 512, an alarm is triggered, by the at least one processor or a processor of the user device, at the user device when the partial discharge value exceeds a pre-defined threshold value.
The steps 502, 504, 506, 508, 510 and 512 are only illustrative and other alternatives can also be provided where one or more steps are added, one or more steps are removed, or one or more steps are provided in a different sequence without departing from the scope of the claims herein.
Modifications to embodiments of the present disclosure described in the foregoing are possible without departing from the scope of the present disclosure as defined by the accompanying claims. Expressions such as “including”, “comprising”, “incorporating”, “have”, “is” used to describe and claim the present disclosure are intended to be construed in a non- exclusive manner, namely allowing for items, components or elements not explicitly described also to be present. Reference to the singular is also to be construed to relate to the plural.
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Claims (16)

1. A substation monitoring system (100) for monitoring a partial discharge in a substation (200) equipped with a transformer (202), the substation monitoring system comprising: - a partial discharge monitoring device (102, 400) comprising at least one sensor that generates sensor data and at least one processor communicably coupled with the at least one sensor, wherein the at least one processor is configured to determine a partial discharge value by processing the sensor data, and wherein the at least one sensor comprises at least: - a high freguency current transformer coil (104, 206, 300) configured to measure current spikes of the partial discharge, wherein the current spikes range from medium to high freguency, and - an ultrasonic microphone (106, 208) configured to measure pressure of sound of the partial discharge, wherein the pressure of sound ranges from low to medium freguency; and - a communication module, communicably coupled to the at least one processor and a user device, wherein the communication module is configured to transmit the partial discharge value, received from the at least one processor, to the user device, 3 wherein the at least one processor or a processor of the user device is N configured to trigger an alarm (108) at the user device when the partial ? discharge value exceeds a pre-defined threshold value. E 25 2. A substation monitoring system (100) according to claim 1, wherein the at least one sensor further comprises at least one of: 3 - a temperature sensor (210), arranged in a medium-voltage section O (216) of the substation, for measuring a temperature of the substation, wherein the temperature sensor is a far-infrared sensor;
- a humidity sensor (220), arranged in a medium-voltage section of the substation, for measuring a humidity of the substation.
3. A substation monitoring system (100) according to claim 1, wherein the substation (200) comprises: - a transformer cabinet (212) having arranged therein the transformer (202); - a low-voltage section (214) having arranged therein a main earth bar (204) and the high freguency current transformer coil (104, 206, 300) arranged at a base part (222) of the transformer; - a medium-voltage section (216) having arranged therein a plurality of disconnector switches (218), the ultrasonic microphone (106, 208), the temperature sensor (210), and the humidity sensor (220), wherein the low-voltage section and the medium-voltage section are on either side of the transformer cabinet; and - a plurality of cable running between the medium-voltage section and the transformer cabinet for connecting the plurality of disconnector switches to the transformer, and wherein the substation is any of a primary substation or a secondary substation.
4. A substation monitoring system (100) according to any of the N preceding claims, wherein the high freguency current transformer coil O (104, 206, 300) measures the partial discharge in a freguency range of 5 100kHz to 2MHz. =
- 5. A substation monitoring system (100) according to any of the , 25 preceding claims, wherein the ultrasonic microphone (106, 208) S measures the pressure of sound in a freguency range of as low as 20 kHz N to 60 kHz. N
6. A substation monitoring system (100) according to any of the preceding claims, wherein the sensor data is generated continuously or intermittently.
7. A substation monitoring system (100) according to any of the preceding claims, wherein the sensor data is generated at 2-second intervals, and wherein a 400 ms peak is sampled from the sensor data.
8. A substation monitoring system (100) according to claim 1, wherein each of the at least one sensor is connected to an I2C port (114) of the substation monitoring system via an I2C splitter.
9. A substation monitoring system (100) according to any of the preceding claims, further comprising monitoring a partial discharge in a switchgear, coupled to the transformer (202), that is configured to interrupt fault currents flowing between circuits, wherein the switchgear includes switches, disconnector switches, fuses and light arrestors.
10. A substation monitoring system (100) according to any of the preceding claims, wherein the substation monitoring system receives power, when in use, from at least one of: an external power source, and a battery unit (120).
11. A substation monitoring system (100) according to any of the N 20 preceding claims, wherein the substation monitoring system, when in = operation, is in at least one of: a normal operating mode; an operating 7 mode comprising a standby mode and a power saving mode; and a transport monitoring mode, and wherein a user interface of the user : device is configured to receive information about an operating mode of 3 25 the substation monitoring system. N N N
12. A substation monitoring system (100) according to claim 1, wherein triggering an alarm (108) is implemented as a notification sent at the user device.
13. A substation monitoring system (100) according to claim 1, further comprising: - a cable fault monitoring arrangement (110) for measuring a fault in cables of a plurality of devices; and - a memory module for storing a plurality of the partial discharge values and the pre-defined threshold value.
14. A substation monitoring system (100) according to any of the preceding claims, wherein the partial discharge monitoring device (102) further comprises: - an amplifier for amplifying at least one of a current and a voltage; - a peak detector for measuring highest partial discharge value; and - an AD converter for converting the partial discharge value into a digital signal.
15. A substation monitoring system (100) according to any of the preceding claims, wherein the at least one sensor is temperature compensated.
16. A method (600) for monitoring a partial discharge, using a substation monitoring system (100), in a substation (200) eguipped with a transformer (202), the method comprising: - arranging at least one sensor near the transformer, wherein the at N least one sensor comprises a high freguency current transformer coil = (104, 206, 300) and an ultrasonic microphone (106, 208); 7 - measuring pressure of sound, ranging from low to medium - freguency, of the partial discharge in a medium-voltage section (216) of , 25 the substation, using the ultrasonic microphone; S - measuring current spikes, ranging from medium to high freguency, 3 of the partial discharge in a low-voltage section (214) of the substation, N using the high freguency current transformer coil;
- determining a partial discharge value by processing the sensor data, using the at least one processor communicably coupled with the at least one sensor; and - transmitting, via a communication module, communicably coupled to the at least one processor and a user device, the partial discharge value, received from the at least one processor, to the user device; and - triggering an alarm (108), by the at least one processor or a processor of the user device, at the user device when the partial discharge value exceeds a pre-defined threshold value.
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FI20225037A 2022-01-17 2022-01-17 Substation monitoring system FI20225037A1 (en)

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CN103913679B (en) * 2014-03-03 2017-08-08 高海涛 High-tension switch cabinet partial discharge monitoring system
CN108919070A (en) * 2018-06-07 2018-11-30 广西电网有限责任公司电力科学研究院 A kind of partial discharge of switchgear detection system of Multi-source Information Fusion
CN108680843A (en) * 2018-08-21 2018-10-19 广西电网有限责任公司电力科学研究院 A kind of method for detection of partial discharge of switch cabinet based on Radio Transmission Technology
CN108710074A (en) * 2018-08-21 2018-10-26 广西电网有限责任公司电力科学研究院 A kind of partial discharge of switchgear detecting system based on Radio Transmission Technology
CN112104071A (en) * 2020-07-08 2020-12-18 国网北京电力公司昌平供电公司 Intelligent substation synthesizes monitored control system based on big dipper thing networking
CN214622883U (en) * 2021-01-25 2021-11-05 上海迈内能源科技有限公司 Multi-parameter online partial discharge monitoring equipment installed inside switch cabinet

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