IEEE Power & Energy Magazine - January/February 2014 - 27

System operators faced a formidable task:
to reassemble the grid and restore power to tens of millions
of customers.
connecticut and Long island had been constructed but had
not yet been authorized to begin operation.
By 12 a.m. on 15 August, 40% of new York load had been
restored, and 60% of new York load was restored by 4 a.m.
on that day. Because the morning load pickup exceeded the
capability of the partially restored system, the emergency
Demand response Program, which calls for voluntary load
reduction, was invoked at 8:59 a.m. When this action proved
insufficient, 300 mW of load west of utica was shed at 9:33
a.m. Area control error at the time was -630 mW. half of this
load was restored at 10:02 a.m., and the rest was restored at
10:24 a.m. By 10:30 p.m. on August 15, 100% of new York
load had been restored.
nYisO found that several lessons were learned from the
experience:
✔ staff duties in the event of such a calamity needed to
be clearly defined.
✔ communications needed to be improved.
✔ A recommendation was made to investigate a formal
process for distributing information to transmission
and generator owners.
✔ it was concluded that restoration training should be
expanded.

New England

threshold of 59.3 hz for the first stage of uFLs in new england. significant oscillations were reported, possibly due
to a misalignment of frequency bias with actual generation
frequency response. the status of the new england system
after the event is shown in Figure 2.
Voltage was initially high after the separation but fell
rapidly owing to the tripping of capacitors (both transmission and distribution) by overvoltage protection and a load
increase over the next 7-10 min. At 4:16 p.m., all fast-start
generation was ordered online. Due to flows on transmission
lines over long-term emergency ratings and low voltages that
prevented generation synchronization, cOnVeX (a local
transmission operator) ordered 500 mW of manual load
shedding (400 mW in connecticut and 100 mW in western
massachusetts), which was completed by 4:40 p.m. Over the
next hour and 10 min, 400 mW of generation was synchronized to the system. the load that had been manually shed
was restored between 5:42 p.m. and 7:28 p.m.
restoration of power to southwestern connecticut was an
ongoing task. stations were manually staffed in southwestern
connecticut. At 9:50 p.m., Danbury, norwalk, and stamford
were reconnected. At 11:23 p.m., the connecticut transmission system was restored except for the ties to new York and
the connections to the middle river substation, which were
high-pressure, fluid-filled cables. By 1:35 a.m. on 15 August,
all distribution buses at bulk substations were energized

new england and the maritimes remained intact, as a single island. the aggregate flow
across the ac ties (i.e., excluding
1,400 MW
dc imports) was very small before
the event, and the total genera150 MW
50 MW
tion loss and load loss during the
event in these areas were nearly
0 MW Citizens
identical (around 3,100 mW).
396
the island was therefore able to
High Gate
remain in relatively stable operaPV-30
tion. southwestern connecticut
had separated along with southK37
east new York and was blacked
K6
out, while about 140 mW in
Phase II HVDC
E205W
393
northern Vermont was also deen690
ergized, apparently in reaction
Total New England Load
398
Lost: 2,500 MW
to oscillations over a 4.5-s interval that drove voltage as low as
1,385 Cable
Cross-Sound Cable DOS
0 MW
0.21 p.u. A small amount of load
had been shed by underfrequency
Blacked-Out Areas
load-shedding (uFLs) relays
that had acted above the standard figure 2. The New England power system island.
january/february 2014

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Table of Contents for the Digital Edition of IEEE Power & Energy Magazine - January/February 2014