IEEE Power & Energy Magazine - July/August 2017 - 93

july/august 2017

billing, and payroll departments of the
Westinghouse east pittsburgh plant.
Of these users, engineers were typically at the bottom of the priority list
and were limited in computing time. In
1965, both ge and Westinghouse used
computers such as this to investigate the
northeast blackout that occurred on 9
november. engineers were forced to

make many modeling compromises and
approximations to simulate an event of
such large magnitude over the several
minutes the event took to develop.

PTI and the
Minicomputer Era
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surprised that the new time burden was
more than offset by not adding and
multiplying by zeroes. He didn't recognize the importance of this work and
wrote it up mainly to get approval to
go to a conference he wanted to attend!
This work was timely and welcome;
just five years later, in 1968, Ibm held
the first Sparse matrix Symposium.
From then on, the use of sparsity was
increasingly adopted in power-flow
solutions, increasing speed and lowering memory requirements by orders of
magnitude. The methods presented in
these papers are used in virtually all
power flow, electromagnetic transient
(emT) and many other programs today.
In the early 1960s, simulation tools
developed in part through competition
between Westinghouse and general
electric. both companies had utility
Headquarters Departments that performed analysis in cooperation with
their customers. each company hoped
to form close relationships with key
managers in utilities and supply the
needed equipment. The study results
were used in the development, improvement, and application of the equipment.
The older analog equipment used by
Westinghouse included dc and ac
boards to solve power flow and some
relay development problems as well as
the anacom, which was an ac passive
circuit analog computer with synchronous switches that investigated switching surge issues in networks. analysis
was done using oscilloscopes and film
cameras to record the system transients.
With the introduction, in the 1960s,
of affordable digital computers with
enough capacity to be useful, mathematical power-flow solution algorithms
such as Tinney's (generally coupled
with short circuit programs, which we
will not discuss separately) were applied
along with transient simulations developed from Kimbark's process. This allowed for the simulation of larger power
system networks, size limited by the capabilities of available digital computers.
Westinghouse maintained a transient stability program that ran on an
Ibm 7094 mainframe computer (see
Figure 4), shared with the accounting,

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Table of Contents for the Digital Edition of IEEE Power & Energy Magazine - July/August 2017