Download Unit.5 Power Quality Monitoring

Unit.5 Power Quality
Monitoring
D.Maharajan Ph.D
Assistant Professor,
Department of Electrical and Electronics Engg.,
SRM University,
Chennai-203
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Unit.5 Power Quality Monitoring- syllabus
Monitoring considerations:
Power line disturbance analyzer,
power quality measurement equipment,
harmonic analyzer, spectrum analyzer, flicker meters,
and disturbance analyzer.
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Monitoring Considerations
The monitoring objectives often determine
the choice of monitoring equipment,
triggering thresholds, methods for data
acquisition and storage, and analysis and
interpretation requirements.
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PQ Monitoring-Introduction
• Power quality monitoring is the process of gathering,
analyzing, and interpreting raw measurement data into useful
information.
• The process of gathering data is usually carried out by
continuous measurement of voltage and current over an
extended period.
• The process of analysis and interpretation has been
traditionally performed manually, but recent advances in
signal processing and artificial intelligence fields have made it
possible to design and implement intelligent systems to
automatically analyze and interpret raw data into useful
information with minimum human intervention.
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Need for PQ Monitoring
• Power quality monitoring programs are often
driven by the demand for improving the
system wide power quality performance.
Many industrial and commercial customers
have equipment that is sensitive to power
disturbances, and, therefore, it is more
important to understand the quality of power
being provided.
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Sensitive to PQ disturbance
Examples
• computer networking
• telecommunication facilities
• semiconductor and electronics manufacturing
facilities
• biotechnology and pharmaceutical
laboratories
• financial data-processing centers.
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Common objectives of power quality
monitoring
• Monitoring to characterize system performanceneed to understand its system performance and then match that system
performance with the needs of customers
• Monitoring to characterize specific problems-
performing short-term monitoring at specific customer sites or at difficult
loads.
• Monitoring as part of an enhanced power
quality service-A provider and customer can together achieve this goal
by modifying the power system or by installing equipment within the customer’s
premises
• Monitoring as part of predictive or just-in-time
maintenance-Equipment maintenance can be quickly ordered to
avoid catastrophic failure.
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Monitoring as part of a facility site survey
1. Nature of the problems (data loss, nuisance trips, component failures,
control system malfunctions, etc.)
2. Characteristics of the sensitive equipment experiencing problems
(equipment design information or at least application guide
information)
3. The times at which problems occur
4. Coincident problems or known operations (e.g., capacitor
switching)that occur at the same time
5. Possible sources of power quality variations within the facility
(motor starting, capacitor switching, power electronic equipment
operation, arcing equipment, etc.)
6. Existing power conditioning equipment being used
7. Electrical system data (one-line diagrams, transformer sizes and
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Quality Monitoring
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impedances,
load information,
capacitor
information, cable data, etc.)
Power quality monitoring concept with
monitoring at the substation and selected
customer locations.
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Some of the categories of equipment that can be
incorporated into an overall monitoring system
1. Digital fault recorders (DFRs).- DFR will typically trigger on
fault events and record the voltage and current waveforms that characterize the
event.
2.Smart relays and other IEDs.
3. Voltage recorders.
4. In-plant power monitors.
5. Special-purpose power quality monitors.
6. Revenue meters.
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Power line disturbance analyzer
• The first generation of power quality monitors began in the mid-1970s
when Dranetz Engineering Laboratories (now Dranetz-BMI) introduced
the Series 606 PLDA.
• This was a microprocessor based monitor-analyzer first manufactured in
1975, and many units are still in service.
• The output of these monitors was text-based, printed on a paper tape.
• The printout described a disturbance by the event type (sag, interruption,
etc.) and voltage magnitude.
• These monitors had limited functionalities compared to modern monitors,
but the triggering mechanics were already well developed.
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Power line disturbance analyzer
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• Second-generation power quality instruments debuted in
the mid1980s.
• featured full graphic display and digital memory to view and
store captured power quality events, including both transients
and steady-state events.
• Some instruments had a capability of transmitting data
from a remote monitoring site to a central location for
further analysis.
• Second-generation power quality instruments virtually had
perfected the basic requirements of the triggering
mechanism. Since the occurrence of a power quality
disturbance is highly unpredictable, data must be
continuously recorded and processed without any dead
time
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• Complex triggering engines determine what data
and how much data should be saved to the digital
memory. Trigger methods include fixed and
floating limits and sensitivities, wave shape
changes, and specific event characteristic
parameters. These methods optimize the
probability that what is important to the user will
be captured and stored.
• By the mid-1990s, the third-generation power
quality instruments
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• By the mid-1990s, the third-generation power quality
instruments emerged. The development of the thirdgeneration power monitors was inspired in part by the
EPRI DPQ project.
• This generation of monitors was more appropriate as
part of a complete power quality monitoring system,
and the software systems to collect and manage the
data were also developed.
• Since the conclusion of the project, substantial field
experience gained revealed some of the difficulties in
managing a large system of power quality monitors
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Third Generation PQ Monitoring
Eq
1. Managing the large volume of raw measurement data that must be
collected, analyzed, and archived becomes a serious challenge as
the number of monitoring points grows.
2. The data volume collected at each monitoring point can strain
communication mechanisms employed to move that data from
monitor to analysis point.
3. As understanding of system performance grows through the
feedback provided by the monitoring data, detailed views of certain
events, such as normal capacitor switching, become less valuable
and would be of more use in a summary or condensed form.
4. The real value of any monitoring system lies in its ability to generate
information rather than in collecting and storing volumes of
detailed raw data.
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Types of instruments used for PQ
Monitoring
A number of different instruments may be used for
measuring PQ problems
• Wiring and grounding test devices
• Multimeters
• Oscilloscopes
• Disturbance analyzers
• Harmonic analyzers and spectrum analyzers
• Combination disturbance and harmonic analyzers
• Flicker meters
• Energy monitors
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Important factors considered when
choosing the instrument
Number of channels (voltage and/or current)
Temperature specifications of the instrument
Ruggedness of the instrument
Input voltage range (e.g., 0 to 600 V)
Power requirements
Ability to measure three-phase voltages
Input isolation (isolation between input channels and from each input
to ground)
• Ability to measure currents
• Housing of the instrument (portable, rack-mount, etc.)
• Ease of use (user interface, graphics capability, etc.)
• Documentation
• Communication capability (modem, network interface)
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• Analysis software
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•
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Benefits of Continuous PQ Monitoring
• Power Quality monitoring provides a continuous
“Health Check” of a facility’s power system … for
example:
o
Harmonic interaction between loads and
power conditioning equipment spotted
o
High Inrush currents from equipment
startup detected
o
Transients from load switching are seen
• It provides data to see, diagnose and avert looming
problems – “like squeaky brakes on a car”
o
Trends can be detected
o
JIT equipment maintenance programs can
be established
• It acts like a “Black Box” on an airplane to tell you
what, when, and where a Power Quality event
occurred … to prevent it from reoccurring
Continuous PQ Monitoring Detects, Records, and Leads to the
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Quality
Prevention
PQMonitoring
Problems
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Power Quality Meter – PQM II
Features:
• All basic electrical parameters
• Data logging and waveform
• Voltage disturbance analyzer
• Analog outputs, digital inputs
• Control relays and KYZ pulses
• Multiple communication ports
• Easy to program and set-up… EnerVista
• Replaces multiple analog meters
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Power Quality Meter – PQM II
• Key Features
– High accuracy, mid range Power Quality with many advanced features.
– Waveform capture using set-points for PQ analysis. Waveform can be
triggered by external equipment (motors) through digital inputs for capturing
start-up current etc….
– Control Relays can open and close at the pre-programmed (min, max etc)
set-points for alarms and notifications.
– Analog outputs for power information to PLCs, RTU
and other non digital
communication devices.
– VERY EASY to use , program and set-up – comes with free set-up and
monitoring software (launch pad).
– Voltage Disturbance Recording for electrical up to 500 sag & swell
events
– Open Modbus and DNP 3.0 protocol over RS 485 with multi port
communication capability
Power Quality with Advanced Voltage Disturbance Recorder
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Target Applications/Industries
– Ideal for circuit monitoring for control panels, switchboards,
Motor Control Centers, Power Distribution Panels.
– Primary Monitoring of low and medium voltage application,
requiring full metering with over 100 different electrical
parameters with data logging and oscillograph (waveform).
– Applications requiring Control Relays with set-point
activation, Analog and digital I/Os.
– Heavy power users for need of clean power - Data Centers,
Pulp and Paper, Oil & Gas…….
– OEMs, Electrical Panel Manufacturers, Switchgear
manufacturers, Motor Control manufacturers…..
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Assignment
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Features
Block Diagram
Each Block Explanation
Target Applications/Industries
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PQ Meter ITI Capture
ITI Acceptable Power
Disturbance Envelope
Damage Inducing Voltage
Surges as Recorded
Equipment Interrupting
Voltage Sags as Recorded
ITI: Information Technology Industry Council (Computer & Business Equipment Manufacturer’s Association)
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Instantaneous Sag Event
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Instantaneous Swell Event
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Harmonic & Interharmonic Spectrum
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References
1. Electric Power System Quality – Roger C.Dugan,
Mark F. McGranaghan, Mark McGranaghan, Surya Santoso, H. Wayne
Beaty, H. Beaty, Tata McGraw-Hill Education.
2. http://www.duke-energy.com/indianabusiness/products/power-quality/power-quality-mitigation
strategies.asp
3. http://www.enetics.com/app-PQM.html
4.http://www.esgroundingsolutions.com/electrical-groundingservices/power-quality-monitoring-and-load-analysis.php
5.http://www.gedigitalenergy.com/multilin/catalog/pqmii.htm
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