TECHNICAL SEMINAR ON POWER QUALITY MONITORING

Presented By:

P.Vinay Kumar

11671D0703

WHAT IS POWER QUALITYThe term Power quality is used to describe the extent

of variation of the voltage, current and frequency on thepower system. The variation of voltage and current can either be in terms of magnitude or waveform shape/distortion.

WHAT IS POWER QUALITY MONITORINGThe best way to detect and diagnose the problems in electrical power system is called Power quality monitoring

Power Quality Monitoring Why monitor? What to monitor? When to monitor? Where to monitor? How to monitor?

Why Monitor?

why Increased currents & losses in the system Lower Energy efficiency Blocked capacity / Higher Investment

Additional heating and lower reliability / life Failure of equipment Mal-function of equipment Poor operational efficiency Poor quality of products manufactured

What to monitor?

what Power Quality Power = Voltage x Current

S=VxI Power Quality = Voltage Quality x Current Quality

Where to monitor?

Where Close to sensitive /critical equipment Close to source PCC / metering point Major Nodes / Branches

When to monitor?

When Before installation of plant / Equipment Before expansion After problem occurrence / suspect

Annually / Periodically Formulation of guidelines Continuously

How to monitor?

HOW TO MONITORPOWER QUALITY PROBLEM VOLTAGE SAG VOLTAGE INTERRUPTION VOLTAGE SWELL TRANSIENT VOLTAGE NOTCH IMBALANCE SOLUTION UPS,DVR,CVT UPS UPS,POWER CONDITIONER SVC SNUBBER CKT PROTECTION SCHEME

DISTORTIONVOLTAGE FLUCTUATION VOLTAGE FLICKERING

SERIES & SHUNT ACTIVE FILTERSVC VOLTAGE UNBALANCED RELAY

PQ Aspects

Voltage - shape & magnitude Steady state limits Frequency Distortion - Frequency content Sags & Swells Transients Unbalance - Phase and magnitude Current- shape & magnitude Magnitude Distortion - frequency content Phase angle Transients Unbalance

POWER QUALITY PROBLEMS 1.Disturbance I. Voltage sag II. Voltage interruption III. Voltage swell IV. Transient V. Voltage notch 2.Imbalance 3.Distortion 4.Voltage fluctuation 5.Voltage flickering

DESCRIPTION 1.DISTURBANCESA DISTURBANCE IS DEFINED AS THE TEMPORARY DEVIATIONFROM THE STEADY STATE WAVEFORM.

VOLTAGE SAGReduction in voltage magnitude for a short period of time.

VOLTAGE INTERRUPTIONVoltage sag with 100% reduction in amplitude.

VOLTAGE SWELLIncrease in RMS voltage or current at the power frequency between 1.1 to 1.9 per unit for a duration of 8milisec to 1min.

TRANSIENTVoltage disturbance shorter than sag/swell and are caused by sudden changes in power system.

VOLTAGE NOTCHPeriodic transient occuring within each cycle.

2.IMBALANCEA SITUATION IN WHICH VOLTAGE,FREQUENCY AND PHASE ALL ARE DIFFERENT.

3. DISTORTIONIT IS GENERALLY EXPRESSED IN TERMS OF HARMONICS WHICH ARE SINUSOIDAL VOLTAGES OR CURRENTS HAVING FREQUENCY THAT ARE INTEGER MULTIPLE OF THE FREQUENCY AT WHICH THE SUPPLY SYSTEM IS DESIGNED TO OPERATE.

4.VOLTAGE FLUCTUATIONTHE RAPID CHANGE IN VOLTAGE MAGNITUDE IN THE ALLOWABLE LIMIT I.E.,

95% TO 105%.

5.VOLTAGE FLICKERINGTHE COLOUR OCCURING WHEN THE FREQUENCY OF VARIATION OF LIGHT FLUX LIES BETWEEN FEW HERTZ AND FUSION FREQUENCY.

Why PQ is such a Big Problem? The sensitivity of todays electronic equipment makes it

susceptible to power disturbances For some devices, a momentary disturbance can cause

scrambled data interrupted communications a frozen mouse system crashes and equipment failure

Who is Affected? High Cost Facilities o Semiconductor plants o Pharmaceuticals o Data centers Medium Cost Facilities o Automotive manufacturing o Glass plants o Plastics & Chemicals o Textiles

Major PQ ProblemsOutages, 6% Spikes, 7%

Swells,31%Swells System fault conditions Switching on a large capacitor bank Switching off a large load

Sags, 56%

Sags (Dips)

Associated with system faultsSwitching of heavy loads Starting of large motors

Cost of Voltage SagsTextile Industry Plastics Industry Glass Industry Process Industry Semiconductors

$1k

$10k

$100k

$1M

$10M

Losses per Voltage Sag Event

HOW DO THEY AFFECT YOU Motors stall Computers crash Production is affected

Equipment damaged Product spoilage The lights go out

BENEFITS OF POWER QUALITY MONITORINGDirect Benefits / Technical Benefits Energy Savings Release of blocked capacity Reduced temperature rise

Increased reliability / Life of equipment (e.g. Transformer,

Motors, capacitors...) Reduced mal-function of equipment (e.g. Drives, Relays,Meters)

Indirect / Regulatory Benefits Penalty savings / Incentives (e.g. Demand charges, pf penalty) Tax benefits Compliance to standards & Regulations

CONCLUSION DISTURBANCES PLACE ALL BUSINESSES AT

RISK BOTH IN TERMS OF FINANCIAL LOSSES AND ENERGY EFFICIENCY SO THEY SHOULD BE TAKEN SERIOUSLY. POWER QUALITY MONITORING IS VERY

ESSENTIAL TO GET AN UNINTERRUPTABLE AND EFFICIENT POWER SUPPLY.

REFERENCES UNDERSTANDING POWER QUALITY PROBLEMS VOLTAGE SAGS &INTERRUPTIONS, MATH H J BOLLEN, IEEE PRESS. AN INTEGRATED APPROACH TO POWER QUALITY IMPROVEMENT, R VENKATESH & S R KANNAN, - ET POWER TECH 2001. SOLUTIONS TO THE POWER QUALITY PROBLEM, PROF. RAY ARNOLD,IEE POWER ENGINEERING JOURNAL, APRIL 2001 POWER QUALITY ISSUES A DISTRIBUTION COMPANY PERSPECTIVE,IEE POWER ENGINEERING JOURNAL, APRIL 2001 MONITORING POWER FOR THE FUTURE, AFROZ K. KHAN, IEEPOWER ENGINEERING JOURNAL, APRIL 2001