IEEE Power & Energy Magazine - November/December 2016 - 23

(a)

(b)

figure 2. The damaged Sylmar converter station: (a) the interior of valve hall and (b) the exterior damage to harmonic
filters and switchyard structures. (Courtesy of Hydro-Quebec.)

For example, a distribution circuit would be de-energized
for about one hour; at the end of the hour, another circuit
would be disconnected, and the first circuit re-energized.
However, due to the severity of the cold (-15 to -20 °C),
at the end of the hour every thermostat would be calling
for heat and energizing the circuit would result in every
furnace trying to start at the same time; this would cause
an overload and trip the circuit breaker at the substation.
Through trial and error, the operating personnel determined that the longest a circuit could be out under these
conditions was not more than 20 min!

If We Build It, the Winds Will Come
This is not an event caused by wind generation, but it demonstrates the power of the wind. During 1960-1962, the utilities
in upstate New York were completing the first major 345-kV
cross-state transmission project to deliver hydroelectric power
from the new Robert Moses Niagara Power Project to eastern and southeastern New York. The eastern segments, constructed by Niagara Mohawk, would turn south at Albany,
cross the Hudson River near Catskill, and continue south to
meet Consolidated Edison's 345-kV transmission system at a
station east of Poughkeepsie. A severe winter storm in the Hudson Valley over the 1962-1963 New Year's holiday brought
blizzard conditions of heavy snow and sustained winds in
excess of 60 mi/h. Towers located on high ground above the
river sustained significant damage. One of the river crossing
spans was damaged, at least two towers on the west side failed
completely, and several more tangent structures sustained
significant damage. Subsequent investigation showed that the
severe cold, heavy snow, and high winds exceeded the design
capability of the towers. The towers were rebuilt and, with
some design modifications applied, have served the system
well for over 55 years.
november/december 2016

Conclusions
The disturbances cited range from relatively small, local
events to large interconnection events and demonstrate a
broad range of initial causes. When that is combined with
unusual or atypical system conditions, the results can be
unexpected to bizarre. The lessons learned from these events
can be useful to preserve and improve the reliability of the
interconnected systems.

For Further Reading
M. Henderson, J. Gagnon, D. Bertagnolli, B. Hosie, G. DeShazo, and B. Silverstein, "Building a plan for HVDC," IEEE
Power Energy Mag., vol. 5, no. 2, pp. 52-60, Mar./Apr. 2007.
345kV river span falls in gusty, frigid wind, Electrical
World, pp. 67, Jan. 14, 1963.
IEEE Guide for Animal Deterrents for Electric Power
Supply Substations, IEEE Standard 1264-2015, 2015.
IEEE Guide for Transmission Structure Foundation Design and Testing, IEEE Standard 691-2001 (R2007), 2007.
IEEE Guide to Installation of Foundations for Transmission Line Structures, IEEE Standard 977-2010, 2011.
NERC Standard on Vegetation Management, FAC-0034, 2016.
FERC summary of vegetation management requirements
(2013). [Online]. Available: http://www.ferc.gov/industries/
electric/indus-act/reliability/vegetation-mgt.asp
NERC events analysis and lessons learned (2016).
[Online]. Available: http://www.nerc.com/pa/rrm/ea/Lessons
%20Learned%20Document%20Library/Forms/AllItems.
aspx

Biography
Robert W. Waldele, retired, was with the New York Indep&e
pendent System Operator, Inc.
ieee power & energy magazine

http://www.ferc.gov/industries/ http://www.nerc.com/pa/rrm/ea/Lessons

Table of Contents for the Digital Edition of IEEE Power & Energy Magazine - November/December 2016