Sreenath B

11EE63R17

05-Apr-121

Phasor Measurement Unit

Contents…

05-Apr-122

GPS

Phasor measurement unit

Architecture

Roadblocks

Conclusion

Introduction

05-Apr-123

Why phasor …?

Digitalization

D F T technique

Local synchronization

Global synchronization : GPS

What is GPS….?

05-Apr-124

Developed by US defense dept

High accuracy clocks

To get the position

A constellation of 24 high altitude satellites

Common time pulse

Accuracy of up to 1 micro sec

05-Apr-125

24 satellites in 6 Orbital planes 20,200 km Altitude

http://engineering.electrical-equipment.org/tag/gps-synchronization

05-Apr-126

V

V

V

1

V

2

Substation 1

Substation 2 t1 t2 t3 t4 t5 t6 t7

GPS time synchronized pulses

V1

V2Ψ

DFT or any other technique gives:

• Magnitude• Phase angle With respect to GPS

http://engineering.electrical-equipment.org/tag/gps-synchronization

05-Apr-127 http://engineering.electrical-equipment.org/power-quality/power-system.html

Features…

05-Apr-128

Time tagged AC phasors

+ve sequence voltages and currents as magnitude and

phase angles

Frequency

Accurate phase angle calculation with accuracy of

upto 1 degree or less

Synchronized sampling with GPS

05-Apr-129

PMU uses discrete Fourier transform (DFT) to obtain

the fundamental frequency components of voltage /

current(Half cycle or Full cycle)

Data samples are taken over one cycle / multiple

cycles.

Currently, sampling is done at 12 samples/cycle (IEEE

C37.111 Std.).

Resolution of the A / D converter is 16 bits.

Absolute time reference

05-Apr-1210http://www.erlphase.com/downloads/papers/08_CIGRE_PMU_Communication_Experience.pdf

Hardware…

05-Apr-1211

Phasor Measurement Units (PMU) placed at strategic

substations

Communication Links, including networking equipment at

substations as well as at control centers

Phasor Data Concentrator (PDC)

Computer systems located at the central control centers,

consisting of servers, storage, workstations and printing

facilities.

Architecture…

05-Apr-1212SOURCE : Practical Implementation of a Security-Dependability Adaptive Voting Scheme Using Decision Trees, Ryan D Quit

Latencies…

05-Apr-1213SOURCE : Practical Implementation of a Security-Dependability Adaptive Voting Scheme Using Decision Trees, Ryan D Quit

Dynamic State Estimation

05-Apr-1214

ConventionalNon-linearAssumptionsSlow convergence & accuracy levels

Dynamic LinearDirectly availableObservabilityCertain delays

SOURCE : Phasor Measurement Units in the Indian Smart Grid : Mohd Rihan,Department of Electrical Engineering,Alighar Muslim University

Other applications…

05-Apr-1215

Adaptive protection schemes

Increased power transfer capabilities

Real time monitoring

Post-Mortem analysis of disturbances and faults

Roadblocks…

05-Apr-1216

Diverse requirements for diff applications

High investment

Lack of related products

PMU placements

Visualization of voluminous data

Communication of data

Conclusion…

05-Apr-1217

PMU will become an integral part of future power

systems.

With increase in fault levels ,faster detection and

isolation are possible with the real time data from

PMU.

With the advent of novel technologies ,PMU may

become cheaper , and a common part in the system.

References…

05-Apr-1218

Practical Implementation of a Security-Dependability Adaptive Voting Scheme Using Decision Trees :Ryan D. Quint, November 11, 2011 ,Blacksburg, Virginia

A.G. Phadke ,etal., “Synchronized Sampling and Phasor Measurements for Relaying and Control,” PSRC working group report, 93 WM 039-8 P WRD, February 1993

A.G.Phadke, J.S.Thorp, R.F.Nuqui, M.Zhou, B, “Recent developments in state estimation with phasormeasurements”, in Proc. IEEE Power Syst. Conf. Expo., 2008.

05-Apr-1219