Qatar University High Voltage Technology and Condition Monitoring Paper I have uploaded Four (4) attachments related to this task. There are Four Questions

Qatar University High Voltage Technology and Condition Monitoring Paper I have uploaded Four (4) attachments related to this task. There are Four Questions below:

The review should clearly/appropriate have the following sections/writeup: (Answer the following points based on attachment named “Partial Discharge Detect”.

1. Title and Author of paper

2. Summary of the paper

3. Relevance of the paper with the subject

4. Methodology used by the author

5.Your comments on the Results/analysis obtained by the author in the paper (your novel thinking-based comments) Strengths of the paper

6. Weaknesses of the paper (It means: disadvantage/not good/dangerous / problems associated with techniques)

Any gap areas spotted (How to overcome the disadvantages or weakness of the paper)

7. List references, if you refer to any other document for the reviewing. [Better take 15-20 papers and list].

Question 1:

To answer Question 1, refer to attachment named “Question 1 Paper1”.

SENARIO: As a research student provide the insulation levels of system equipment and rating of the surge arresters considered by various utilities for EHV 400kV Transmission.

Q.1 The comparison with the protection levels of the arresters shows that the improved/modern system protection against lightning and switching surges is attainable using certain schemes. (500 words)

Question 2:

To answer Question 2, refer to attachment named “Question 2 Paper2”.

SENARIO-2: As a high voltage technology researcher use link to see the Impulse testing systems are designed to generate impulse voltages that simulate lightning strikes and switching surges. The complete test system consists of a charging rectifier, impulse stages according to the “Marx Circuit”, an impulse voltage divider and impulse voltage measurement system. The applications are defined by I-E-C, ANSI/IEEE and other national standards.

Impulse Test Sets are also available as current impulse generators used primarily for surge arrestor testing. HV TECHNOLOGIES, Inc. has a long tradition of supplying impulse generator for HV applications as well as impulse test systems for the EMC and avionics, military industries. https://hvtechnologies.com/hv-equipment/impulse-testing provide the answer:

Q2. Sketch (by hand) and describe the principle behind the multistage(n-stage) of high voltage and current generation (500 words)

Question 3:

To answer Question 3, refer to attachment named “Question 3 Paper3”.

SENARIO 3: Assets management is composed of number of stages, power apparatus information management and monitoring, risk assessment, and various visualization for diagnostic result. In the first, the operator registers the power apparatus’s information, manages its maintenance history, and monitors its status information.

Q3. Sketch a substation at [ for example 11/33kV or 11/66kV or 33/132kV or any other type] generation side or transmission side or distribution diagram (by hand) and describe the any assets management techniques. (500 words)

*** Words count = minimum 2000 words.

*** In-Text Citations and references using Harvard style.

*** Note that: Question 2 and Question 3 has “Hand sketch”.

*** I have uploaded Four (4) attachments:

-“Partial Discharge Detect” file.

-“Question 1 Paper1” file.

-“Question 2 Paper2” file.

-“Question 3 Paper3” file. PHOTONIC SENSORS / Vol. 4, No. 4, 2014: 325–337
Review on Partial Discharge Detection Techniques Related to
High Voltage Power Equipment Using Different Sensors
MM YAACOB1, MA ALSAEDI1,2*, JR RASHED2, AM DAKHIL2, and SF ATYAH2
1
Institute of High Voltage and High Current, Faculty of Electrical Engineering, Universiti Teknologi Malaysia
2
Department of Electrical Engineering, College of Engineering, Misan University, Iraq
*
Corresponding author: MA ALSAEDI
E-mail: maliksaady@yahoo.com
Abstract: When operating an equipment or a power system at the high voltage, problems associated
with partial discharge (PD) can be tracked down to electromagnetic emission, acoustic emission or
chemical reactions such as the formation of ozone and nitrous oxide gases. The high voltage
equipment and high voltage installation owners have come to terms with the need for conditions
monitoring the process of PD in the equipments such as power transformers, gas insulated
substations (GIS), and cable installations. This paper reviews the available PD detection methods
(involving high voltage equipment) such as electrical detection, chemical detection, acoustic
detection, and optical detection. Advantages and disadvantages of each method have been explored
and compared. The review suggests that optical detection techniques provide many advantages in the
consideration of accuracy and suitability for the applications when compared to other techniques.
Keywords: PD detection methods, power transformer, high voltage equipments
Citation: MM YAACOB, MA ALSAEDI, JR RASHED, AM DAKHIL, and SF ATYAH, “Review on Partial Discharge Detection
Techniques Related to High Voltage Power Equipment Using Different Sensors,” Photonic Sensors, 2014, 4(4): 325–337.
1. Introduction
Stability of any power system network is
determined mainly by the high voltage equipment
used. Failure of this equipment is normally related to
partial discharge (PD) activity which deteriorates the
system performance and can lead to breakdowns,
fires or irreparable damage to the system. PD
detection is necessary as precautionary measures to
ensure that high voltage equipment insulation is not
exposed to any unnecessary hazards. A good
understanding of PD mechanisms, characteristics,
and its development processes is essential for power
system designer and power system installation
maintenance engineer.
There is a high risk of insulation system
dielectric instability when PD occurs. Therefore,
measurement and monitoring of PD is an important
preventive tool to safeguard the high-voltage
equipment from wanton damage. Techniques for
detecting PD depend on what different physical
properties which accompany the occurrence of PD,
are measured. Known physical properties which
have been used in the measurement include
electromagnetic emission (in the form of radio wave,
light, and heat), acoustic emission (in the audible
and ultra-sonic ranges), ozone formation, and the
release of nitrous oxide gases [1]. The measurement
level indicates the quantity and magnitude of partial
discharge. Popular methods of PD detection in the
high-voltage power equipment utilize electrical,
chemical, acoustic or optical measurements.
Received: 27 September 2013 / Revised version: 30 May 2014
© The Author(s) 2014. This article is published with open access at Springerlink.com
DOI: 10.1007/s13320-014-0146-7
Article type: Review
326
Measurement of an electrical quantity is convenient
and can give precise recording of PD variations in
the laboratory. However, it can give an inaccurate
recording for conditions at on-site (for example to
monitor in-service transformers). The inaccuracy is
due to the various disturbances and interferences
which can result in the high environmental noise
level.
Two electrical quantity measurement methods
are available. They are the ultra high frequency
(UHF) method and pulse capacitive coupler method.
The UHF method is based on the measurement of
electrical resonance at the frequency range of up to
1.5 GHz due to PD excitation. This method is
capable of detecting as well as locating a PD source
[2, 3]. The UHF method has inherent advantages
such as low noise levels due to the shielding effect
of the transformer and very low signal attenuation.
The UHF method can also avoid local interference
throughout the 100 MHz of its operating
measurement frequency band which nestles in the
whole UHF band range between 300 MHz and
1500 MHz. This method has immunity against
external noise as the UHF sensor is connected inside
the transformer. The connection between the UHF
sensor and power transformer is non-electrical, and
hence there is reliability and safety against any
induced current at the power secondary.
The pulse capacitive coupler method collects
and measures the PD induced current at the
detection coil which has a connection loop through
some impedance to the earth line [4]. Quantitative
measurement has the good sensitivity and great
implementation simplicity. However, it is prone to
false alarm due to this high sensitivity, and it is
therefore not suitable for long-term monitoring of
transformers.
The chemical measurement techniques for
detecting PD in the high voltage transformer are
based on the collection and some chemical
measurement of oil and gas samples released during
the PD process. Two chemical measurement
Photonic Sensors
techniques are used at the present moment. They are
the high performance liquid chromatography method
(HPLC) and the dissolved gas analysis method
(DGA). The HPLC analyses PD expelled byproducts
such as degraded forms of glucose induced by
degradation of insulation [5, 6], while the DGA
analyses the accumulated volume of the gas
produced by the PD. For chemical measurement
techniques, sufficient expelled byproducts or gas has
to be collected before analysis can begin. Hence,
there is some time delay between collection and
analysis. Chemical measurement techniques are
therefore not suitable for real-time monitoring.
Chemical as well as electrical approaches are
incapable of locating the exact position of PD
sources.
The acoustic method detects and locates the
position of the PD by studying the amplitude
attenuation or phase delay of the acoustic waves
propagating from the PD. This mechanical wave
(acoustic wave) is caused by the mechanical energy
explosion due to the vaporization of the material
inside the transformer tank creating a form of the
pressure field [7–11]. The acoustic wave in the
transformer oil can be detected using acoustic
sensors (piezoelectric transducers – PZT). When the
PZT is mounted outside, on the transformer wall, it
will capture interferences from the very noisy
environment, and this can make PZT sensors’
usefulness limited. The PZT sensor can be placed
inside the oil tank of the transformer to reduce the
noise and attenuation of the signal [12]. The location
of the PD can be estimated by measuring the time of
arrival of the acoustic wave, and position
information is ascertained by using sensors at
multiple locations. This makes acoustic emission
sensing a more preferable measuring tool in real
time of PD signal detection, Measurement using the
acoustic approach has an additional advantage of
possessing better noise immunity for online
real-time applications. Occasionally, the acoustic
method experiences difficulty in locating the exact
MM YAACOB et al.: Review on Partial Discharge Detection Techniques Related to High Voltage Power Equipment Using
Different Sensors
origin of the PD due to interference/degradation of
signals from the environmental noise [13, 14]. Here,
the sensitivity is certainly compromised.
The optical method that uses the optical fiber
sensor which is small in size, highly sensitive and
light weight, and possesses high frequency response
and significant immunity against electromagnetic
interference, can measure a wide range of chemical
and physical parameters at ease. Apart from PD
detection and assessment [15], optical fiber acoustic
sensors have been used successfully in applications
such as underwater hydrophones, construction
non-destructive diagnosis, material property analysis
[16], traffic monitoring, and vehicle detection.
Functionally, the optical detection technique is based
on fiber optic intrinsic interferometers such as
Michelson
interferometers,
Mach-Zehnder
interferometers, multimode fiber and fiber optic
extrinsic such as Fabry-Perot interferometric sensors.
The Michelson interferometers, Mach-Zehnder
interferometers sensors suffer from fringe fading
problems due to random polarization rotation. The
Fabry-Perot interferometric sensors are compact in
size compared to the Michelson and Mach-Zehnder
fibre sensors and therefore achieve virtually singlepoint measurement. Due to the measurement
sensitivity, the optical method has the restricted use
for PD detection
327
the insulating materials, sometimes over a period of
several years, leading perhaps to eventual failure.
Locating and detecting the PD in the power
transformers is vital both in industries and utilities to
avoid the damage of the high-voltage equipment [17,
18]. Figure 1(a) shows the UHF sensor to detect PD
in gas insulated substations (GIS). This type of
sensor has been proven effective not only for
laboratory test but also for on-site PD. Figure 1(b)
shows the UHF sensor to test the power transformer
for usage on DN50/DN80 gate valve. The sensor
allows alternative ways to estimate PD, and the
configuration shown is known as bushing-tap which
is suited for the measurement made on galvanic
connected decoupling. Figure 1(b) shows an
inductive UHF sensor setup for the measurement on
the power cable termination [19]. Figure 2 shows
three types of UHF sensors which can be used to
characterize PD on the power transformer and GIS.
They are the disc-type, monopole-type, and
spiral-type. The disc-type, monopole-type, and
spiral-type sensors can provides the greatest energy
accumulation in the laboratory test, which indicates
that the sensors have the high sensitivity for
detecting radiated signals [20]. Figure 3 shows a
capacitive coupler for partial discharge detection in
2. Sensors for the detection of the PD
phenomenon
2.1 Sensors for electrical quantity measurement
PD is an electrical discharge or spark that
partially bridges a small section of insulation when
two conducting electrodes emerge from the
separation of distinct high concentration of positive
and negative charges. It is a random localized
discharge formed by transient gas ionization in an
insulated system when the stress voltage exceeds a
certain critical value. PD often occurs when the
electric field strength exceeds the breakdown
strength of insulation and can lead to a flashover.
The PD phenomenon causes gradual deterioration of
(a)
(b)
(c)
Fig. 1 Elecrical sensors: (a) UHF sensor adapted to a GIS
grounding bar, (b) oil valve sensor for the power transformer
reactor e.g. left side for usage on DN 50 gate valve, and right
side for DN 80 gate valve, and (c) inductive UHF sensor for the
power cable termination [19].
Photonic Sensors
328
the high voltage cable. The 40-mm tin tape wrapped
around the exposed cable acts as a coupler for the
capacitive sensor. The capacitive sensor coupler
does not interfere with the measurement on the
insulation of the cable because at the UHF the
capacitive coupler is effectively connected and
works as the power frequency ground [21].
Monopole-type
Disc-type
0.06 m
0.12 m
0.04 m
Spiral-type
Fig. 2 Three types of UHF sensors: disc-type, monopoletype and spiral-type [20].
such as power transformers and high voltage (HV)
cables. At low resonant frequencies, the
piezoelectric sensor film is a crystal which is in the
form of a disc, for which resonances can be
calculated easily [22].
2.3 Sensors for optical detection
Currently, the most popular method for detecting
PD in the high voltage transformer and other
equipments such as the GIS is the optical detection
method which uses the fiber intrinsic sensor coil, the
detail of which is shown in Fig. 5(a). The fiber
intrinsic sensor coil is made by winding 8 m of fiber
around a former into a coil of 25 mm in diameter.
The single mode optical fiber intrinsic sensor is
based on Mach-Zehnder fiber interferometers and is
normally immersed in the oil within the walls of the
transformer whose PD characteristics are being
measured [23]. Figure 5(b) shows the multimode
optical fiber sensor for partial discharge detection in
the GIS [24] while Figs. 6(a) and 6(b) show the
Fig. 3 Diagram of a capacitive coupler [21].
2.2 Sensors for acoustic detection
The acoustic technique which uses a highly
sensitive piezoelectric film sensor shown in Fig. 4(a)
and configured as in Fig. 4(b) has applications to the
measurement of PD for the high-voltage equipment
Fig. 5 Optical sensors (intrinsic): (a) optical fiber intrinsic
sensor based on Mach–Zehnder fiber interferometers [23] and
(b) Intrinsic multimode optical fiber sensor [24].
Connector
Metal case
Pre-amplifier
Piezoelectric
crystal
Conducting
electrodes
Plastic protective shoe
(a)
(b)
Fig. 4 Acoustic sensors: (a) piezoelectric film sensor with its
connector and (b) typical design of the piezoelectric transducer
sensor [22].
(a)
(b)
Fig. 6 Optical sensors (extrinsic): (a) extrinsic Fapry-Perot
interferometer
sensor
[25]
and
(b)
extrinsic
microelectromechanical system sensor [25].
MM YAACOB et al.: Review on Partial Discharge Detection Techniques Related to High Voltage Power Equipment Using
Different Sensors
extrinsic Fapry-Perot interferometer sensor and
extrinsic microelectro-mechanical system sensor
which have applications to the measurement of PD
of the oil cooled high voltage transformers [25].
3. PD detection process
3.1 Electrical detection
Under the influence of the intensive electric field,
the PD activity starts with the transfer of electrons in
short current bursts in micro void gaps. The void
space charge is transferred to adjacent voids within
the time frame of nanoseconds. The recharge
process impulse can be detected with the aid of the
(0.1 nF –1 nF) coupling capacitor. The resolution,
polarity, and arrival speed of the PD induced
impulse are registered [26]. With nanosecond (ns)
arrival time of PD induced impulses, the signal
generated by the activity of PD would be in the
frequency range between 300 MHz and 3 GHz (UHF
band). With the appropriate calibration, PD signals
detected can be used as diagnosis of the insulation
condition for the GIS, transformer, and cable. The
detection process has the wide detection range, high
sensitivity, and minimal external disturbances[27].
This property is an important consideration for
monitoring insulation safety [28]. A major reason for
the success in the use of the UHF method to
measure PD in the GIS is the fact that the PD current
pulse has short rise time (
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