UNIT.5 POWER QUALITY - SRM · PDF file20/09/2012 Unit.5 Power Quality Monitoring 3 Monitoring Considerations The monitoring objectives often determine the choice of monitoring equipment,

20/09/2012 Unit.5 Power Quality Monitoring 1

D.MaharajanD.Maharajan Ph.DPh.D

Assistant Professor,Assistant Professor,Department of Electrical and Electronics Department of Electrical and Electronics EnggEngg.,.,

SRM University,SRM University,

ChennaiChennai--203203

Unit.5 Power Quality Unit.5 Power Quality

MonitoringMonitoring


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.


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.


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.


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.


Sensitive to PQ disturbance

Examples

• computer networking

• telecommunication facilities

• semiconductor and electronics manufacturing

facilities

• biotechnology and pharmaceutical

laboratories

• financial data-processing centers.


Common objectives of power quality

monitoring

• Monitoring to characterize system performance-need 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.


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

impedances, load information, capacitor information, cable data, etc.)


Power quality monitoring concept with

monitoring at the substation and selected

customer locations.


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.


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.


Power line disturbance analyzer


• 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


• 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


• By the mid-1990s, the third-generation power quality instruments emerged. The development of the third-generation 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


Third Generation PQ Monitoring

Eq1. Managing the large volume of raw measurement data that must be

collected, analyzed, and archived becomes a serious challenge asthe number of monitoring points grows.

2. The data volume collected at each monitoring point can straincommunication 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 valuableand 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.


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


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)

• Analysis software


Benefits of Continuous PQ Monitoring

Continuous PQ Monitoring Detects, Records, and Leads to the

Prevention of PQ Problems

• 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


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

Power Quality Meter – PQM II


Power Quality with Advanced Voltage Disturbance Recorder

• 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 Meter – PQM II


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…..


Assignment

• Features

• Block Diagram

• Each Block Explanation

• Target Applications/Industries


PQ Meter ITI Capture

Equipment Interrupting

Voltage Sags as Recorded

Damage Inducing Voltage

Surges as Recorded

ITI Acceptable Power

Disturbance Envelope

ITI: Information Technology Industry Council (Computer & Business Equipment Manufacturer’s Association)


Instantaneous Sag Event


Instantaneous Swell Event


Harmonic & Interharmonic Spectrum


References

1. Electric Power System Quality – Roger C.Dugan,Mark F. McGranaghan, Mark McGranaghan, Surya Santoso, H. WayneBeaty, H. Beaty, Tata McGraw-Hill Education.

2. http://www.duke-energy.com/indiana-business/products/power-quality/power-quality-mitigationstrategies.asp

3. http://www.enetics.com/app-PQM.html

4.http://www.esgroundingsolutions.com/electrical-grounding-services/power-quality-monitoring-and-load-analysis.php

5.http://www.gedigitalenergy.com/multilin/catalog/pqmii.htm

Documents

UNIT.5 POWER QUALITY - SRM · PDF file20/09/2012 Unit.5 Power Quality Monitoring 3 Monitoring Considerations The monitoring objectives often determine the choice of monitoring equipment,