Dr. Hannan Week9 Power Quality Monitoring

8/2/2019 Dr. Hannan Week9 Power Quality Monitoring

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Power Quality Monitoring

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 voltage and current over and extended period.

Why needed?

What are the objectives/consideration?The monitoring objectives often determines the choice monitoring equipment, triggering threshold,

methods of data acquisition and storage, analysis and interpretation requirements. There are

several common objectives of power quality monitoring such as

i) Monitoring to characterize system performance

ii) Monitoring to characterize specific problems

iii) Monitoring as a part of an enhanced power quality service

iv) Monitoring as a part of predictive or just-in-time maintenance



Monitoring as part of a facility site survey

Site survey are performed to evaluate concerns for power quality and equipment performance

throughout a facility. The survey will includes inspection of wiring and grounding concerns,equipment connections, and voltage and current characteristic etc. This information is specially

important when monitoring objective intended to address specific PQ problems. This information

are as follow;

i) nature of problems

ii) Characteristics of sensitive equipment experiencing problems

iii) time at which problems occur

iv) Coincident problems or known operationv) possible source of power quality variations

vi) existing power conditioning equipment being used

vii) Electrical system data



Forms for RecordingForms for Recording

Data forms that can used for initial verification of

PQ disturbances are as follows;



Locations &permanent PQ monitoring equipment

Some categories of equipment that

are used for permanent PQmonitoring system such as;

i) Digital fault recorder

ii) Smart relays and other LEDs

iii) Voltage recorderiv)In-plant power monitor

v) Special purpose PQ monitor

vi)Revenue meter etc.



Historical perspective of PQ measuring instruments

►The instrument makes an impulse-like mark on strip-chart paper to record lighting strikes.

►Analog oscilloscope with logarithmic chart sweep rate and recorded quantitative voltage waveform



Historical perspective of PQ measuring instruments

►Microprocessor based monitor

analyzer 1st manufac. in 1975.

This text based printout of adisturbance, still in service.

►2nd generation PQ instrument

debuted in mid 80’s. Feature full

graphic display, digital memoryto view and store captured

events. Capable data

transmission from remote to

central location for further

analysis and also have triggeringmechanism.

►3rd generation are in mid 90’s

inspirited by EPRI DPQ project,

more appropriate than previous,complete PQ monitoring,

software based data collection

and analysis.



Power Quality Measuring InstrumentsPower Quality Measuring Instruments

►There are numbers of PQ measuring instruments that can measure power quality are as follows;

i) Wiring and grounding test device

ii) Multimeters

iii) Oscilloscopes

iv) Disturbance analysers

v) Harmonic analysers and spectrum analysersvi) combination disturbance and harmonic analysers

vii) Flicker and

viii) Energy monitor

Besides these meters, there are some other meters that can help to solve PQ problems bymeasuring ambient conditions such as;

i) Infrared meter

ii) magnetic gauss meter

iii) Static electricity meters



Wiring and grounding tester/multimetersWiring and grounding tester/multimeters

►Many power quality problems are reported by end users are caused by problems with wiring and

or grounding within the facility. Important capability for a wiring and grounding test

includes;

i) Detection of isolated ground short and neutral-ground bonds.

ii) Ground impedance and neutral impedance measure

iii) Detection open neutral, open ground and open hot wires

iv) Detection of hot/neutral reversals or neutral/ground reversals

After wiring test, a quick check of voltage and current measurements within the facility are to be to

Be taken for overloading, under and over voltage and unbalance problems detection. Signal also

used to check as follows;

i) Phase to ground voltages

ii) Phase to neutral voltages

iii) Neutral to ground voltages

iv) Phase to phase voltages

v) Phase currentsvi) Neutral currents



Oscilloscope/Disturbance analyzersOscilloscope/Disturbance analyzers

Digital oscilloscope: data storage available for analysis i. e. energy calculation and spectrum analysis

Communication to pc for additional analysis using software.Over

Hand-held oscilloscope: Display waveform, performing signal processing, portable and permits

connection with PC for further data analysis.

Disturbance Analyzer: Disturbance analyzer and monitor measure a wide variety of systemdisturbances from short duration transients to long duration outage or undervoltage. Basically,

there are two types;

Conventional analyzers: Over voltage/under voltage magnitudes, sag and surge magnitude and

duration, transient magnitude and duration

Graphics-based analyzers:Display, save and print the actual waveform of the disturbances



Oscilloscope/Disturbance analyzersOscilloscope/Disturbance analyzers



Spectrum analyzers and harmonic analyzers

►FFT calculation for determining low order harmonics. There some important Capabilities of

this instrument:

i) Capability to measure both voltage and

current to get harmonic power flow information

ii) Capability to measure both magnitude and phase

angle of individual harmonic also to get powerflow information

iii) Synchronization and fast sampling to obtain

accurate harmonic component

iii) Capability to characterise nature of harmonic

distortion level

There are basically three types of instrument to

consider for harmonic analysisi) Simple meter ii) General purpose spectrum

analyser iii) Special purpose power system harmonic analyser.



Flicker meter

►Flicker meter measures the level of flicker. The flicker evaluation level can be divided into two

Categories such as follows;

i) Short term Pst: Evaluation of flicker severity based on an observation period of 10 minute

Where the percentages P0.1, P1.0s, P3.0s, P10.0s and P50.0s are the flicker level that are exceeded0.1, 1.0, 3.0, 10,0 1nd 50.0 percent of time, respectively.

ii) Long term PLT: The long term variation flicker assessment of flicker severity is determined by

using PST equation

Where N is the number of PST reading and is determined by the duty cycle of flicker producing load

SSSSST PPPPPP5010311.0

08.028.00657.00525.00314.0 ++++=

N

P

P

N

i

ST

LT

∑== 1

3.



IEC Flicker meter



Flicker meter



Summary of Monitoring Equipments CapabilitiesSummary of Monitoring Equipments Capabilities

Digital oscilloscope: data storage available for analysis i. e. energy calculation and spectrum analysis

Communication to pc for additional analysis using software.



Assessment of PQ Measurement DataAssessment of PQ Measurement Data

Data assessment of PQ is meant by the data management, analysis, and interpretation function of

overall PQ monitoring efforts. As well as shifting off-line to on-line operation for automatic

problems identification.

There are two stream of power quality data assessment such as follows;

i) Off-line PQ data assessment: the off-line PQ data assessment is performed off-line i.e. it is

carried out separately from the monitoring instruments that is at the central processing

locations.

ii) On-line PQ data assessment: On-line data assessment is performed within instrument for

immediately information dissemination



PQ Off PQ Off --line Data Assessmentline Data Assessment



PQ OnPQ On--line Data Assessmentline Data Assessment



Application of Intelligent Systems

►The application of intelligent systems or

expert system in monitoring instrument help

engineer the system condition rapidly. Theimplementation of intelligent systems within

a monitoring Instrument can significantly

increase the value of monitoring application

since it generate information rather than just

collect data. Intelligent system module performto analyse capacitor switching transient and

determine the location of capacitor bank,

determine fault location etc.

Basic Design of an expert system for monitoringapplication



Voltage Sag Direction Module

►An autonomous expert system module called voltage sag direction module is designed just for to

detect and identify of a voltage sag event and subsequently determine the origin (upstream/

downstream) of the voltage sag event. The module can displayed computer screen using web browser

Software, displayed printed paper format, or sent as an e-mail etc.



Types of Intelligent PQ monitoring Systems

►There are many advance PQ monitoring system are equipped with off-line and on-line

intelligent systems to evaluate disturbances and system conditions so as make conclusionabout the cause of the problems before they occur. Out of many, the three types are

as follows.

i)Industrial PQ monitoring application

ii)Power system performance assessment and benchmarking

iii)System maintenance, operations and reliability applications



Industrial PQ Monitoring Applications



Power Sys. Perfm. Assessment and Benchmarking



Application for System Main. Optn. and reliability



PQ Monitor and the Internate



Power Sys. Perfm. Assessment and Benchmarking

Dr. Hannan Week9 Power Quality Monitoring

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