IEEE Power & Energy Magazine - September/October 2015 - 59

not oscillating initially, which is the normal operating condition. After few seconds, spontaneous oscillations were
observed, and after the special protection scheme operation,
it again come back to normal operating condition.

URTDSM
Most programs for WAMS technology have three stages to
implement phasor technology. The initial stage is to collect and archive phasor and frequency data from important
locations throughout the grid using PMUs to determine the
topology and operating limits. In the second stage, the data
is gathered along with real-time phasor and frequency measurements to calculate grid conditions using analytical functions to make suggestions to the grid operator to keep the grid
stable and reliable. The third and final stage is to do all of
these automatically without human intervention. Recognizing the need for WAMS applications in the Indian power system, PGCIL has embarked on the URTDSM project with the
installation of PMUs on substations at the 400-kV level and
above in the state and central grids; all generating stations at
the 220-kV level and above HVdc terminals; important interregional and international connection points; and provision
of PDCs at all SLDCs, RLDCs, and the NLDC along with
visualization aids are in the anvil in the first phase. In the subsequent phases, developing software-based analytic functions
will be undertaken. Based on the availability of existing fiber
optic (FO) communication links as well as FO links under
implementation, the implementation may be undertaken in
two phases: Phase 1, where substations with FO links would
be available by 2015-2016, and Phase 2, in balance substations where separate FO links will be established.

Conclusions
The following are the future courses of action;
1) The oscillation monitoring system, which has been
installed at RLDCs/NLDCs in the pilot projects,
needs further enhancement. It was found that the
OMS at the national control center and the regional
control centers supplied by the same vendor is capable of performing oscillation analysis only for a
single signal. The OMS engine at the western regional control center is able to perform oscillation
analysis on various PMU data with ambient as well
as event-based engine implementations. The OMS
engines currently are not generating any alarms for
the system operator. With such a fast data rate (25
samples/s), the operator may not be able to notice the
events; if a large amount of data is displayed then
this will not be helpful to the operator. The number
of screens before the operator and the time window
displayed are also very important. A 10-min window
is useful to detect oscillations but may be too less
if the operator is busy in a telephonic conversation
or coordinating any outage activity. In view of these
challenges, the various criteria for better oscillation
september/october 2015

monitoring system need to be defined, which will
help the operator in easy detection:
2) Along with these, other PMU applications, which
need further attention, are the following:
* event-based alarms in real time for the operator with
complete observability of the system
* event classification based on data mining and a
knowledge-based system
* alarms based on the PMU's digital flag
* much effort in contour-based visualization of the Indian grid in terms of voltage for better situational
awareness of the operator at each level (SLDCs/
RLDCs/NLDC)
* dynamic state estimation or hybrid state estimation to
be provided in conjunction with the dynamic line rating;
this is required for the operator to have more confidence
while utilizing the dynamic line rating in real time.
Above all, robust and redundant communication links are
needed for the transfer of PMU data as it is observed in the current pilot project; communication is a serious bottleneck. This
needs to be improved as the number of PMUs being monitored
increases. The Indian power sector is on a roll, and synchrophasor applications have added value and invaluable insights into
system operations and are poised to leapfrog as a primary tool in
the control center operations.

For Further Reading
S. K. Soonee, S. R. Narasimhan, R. K. Porwal, S. Kumar,
R. Kumar, and V. Pandey, "C2-107, application of phase angle measurement for real time security monitoring of Indian
electric power system-An experience," in Proc. CIGRE
General Session, Paris, France, 24-29 Aug. 2008.
POSOCO. Reports on synchrophasors initiative in India.
[Online]. Available: http://posoco.in/2013-03-12-10-34-42/
synchrophasors
Power Grid Corporation of India. (2012, Feb.). Unified
real time dynamic state measurement (URTDSM). [Online].
Available: http://www.cea.nic.in/reports/powersystems/sppa/
scm/allindia/agenda_note/1st.pdf
S. K. Soonee, V. K. Agrawal, P. K. Agarwal, S. R. Narsimhan, R. K. Porwal, and V. Pandey, "Experiences of synchrophasors initiative in India," in Proc. CIGRE 2014 General
Session, Paris, France, 24-29 Aug. 2014.

Biographies
S.K. Soonee is with Power System Operation Corporation
Ltd, New Delhi, India.
V.K. Agrawal is with Power System Operation Corporation Ltd, New Delhi, India.
P.K. Agarwal is with Power System Operation Corporation Ltd, New Delhi, India.
S.R. Narasimhan is with Power System Operation Corporation Ltd, New Delhi, India.
Mini Shaji Thomas is with Jamia Millia Islamia University, New Delhi, India.
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http://www.posoco.in/2013-03-12-10-34-42/ http://www.cea.nic.in/reports/powersystems/sppa/

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