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