of May 13, 1966, the Northeast Power Coordinating
Council has completed studies under 1968 conditions to
supplement the FPC SSG studies that had been conducted under
1966 conditions.
Enclosed is the report of our Task Force on System
Studies entitled
Study of the Effect of Possible, but
Improbable Events on the Northeast Power Interconnected
Sys terns under 1968 Conditions.
As indicated in my letter, the results of this series
of tests show the effect of major generation

transmission
additions, but do not include
effect of all other possible
changes, as for example, in protective devices, that are under
study and may be made prior to
We trust that this report will be of aid to the
Commission in the preparation of its final report.
It is the purpose of the Council to promote maximum
reliability and efficiency of electric service in the Nqrtheast
Power interconnected system by extending the coordination of
planning and operating
of its members.
The Council is carrying on several studies in furtherance of
this purpose and the enclosed
covers only one phase of
these activities.
The Council has adopted a Procedure for Action in a
Major Emergency as a first step in the development of
load reduction procedures and
is undertaking
immediate studies of current load reduction techniques, including
the application of automatic equipment, for further consideration
of its membership. Studies have been conducted to determine critical
switching time in certain key areas and plans are underway
to modify protective schemes to obtain faster backup
clearing and to obtain isolation of the affected area to
prevent the occurrence of widespread interruptions. We feel
that each of these steps will further reduce the already
low probability of occurrence of a widespread interruption
from the "possible but improbable" events.
Yours sincerely,
Ernest R.
Chairman
Encl. A Study of
The Effect of Possible, but Improbable Events
on the
Northeast Power Interconnected Systems under 1968 Conditions
Northeast Power Coordinating Councils
Task Force on System Studies
September 21, 1966 TABLE OF CONTENTS
Page No.
NPCC Task Force on System Studies
i
Letter from Mr. E. R.
to
Mr. F. S. Brown, dated May 13, 1966
Purpose
Introduction
Analysis of Tests
Summary of Results
Conclusion
ii
1
2
3
8
8
Tables
I
Scheduled Major Generation and Transmission
Additions Included in 1968 Tests
II
Comparison of Base Load Flows
III
Comparison of Transient Stability Tests
Exhibits
1
1966 Base Load Flow Used by FPC System
Studies Group Test 590-105
2
1968 Base Load Flow Used by NPCC Task Force
Test
10
3
Generation Swing Curves Case 1.53
(1966 System)
4
Generation Swing Curves Case 1.53
(1968 System) Table of Contents
Exhibits
5
6
7
a
9
10
11
12
13
14
Generation Swing Curves Case 1.71
(1966 System)
Generation Swing Curves Case 1.71
(1968 System)
Generation Swing Curves Case 1.72
(1966 System)
Generation Swing Curves Case 1.72
(1968 System)
Generation Swing Curves Case 8. 11
(1966 System)
Generation Swing Curves Case 8. 11
(1968 System)
Generation Swing Curves Case 9.32
( 1966 System)
Generation Swing Curves Case 9.32
(1968 System)
Generation Swing Curves Case 10. 11
(1966 System)
Generation Swing Curves Case 10. 11
(1968 System) Northeast Power Coordinating Council
Task Force on System Studies
Members
Affiliation,
K. W. Amish, Chairman
Rochester Gas and Electric Corporation
i
Consolidated Edison Company of New York, Inc.
W.
Balet, Secretary
P. L. Dandeno
The Hydro-Electric Power Commission of Ontario
Einar Gr eve
Power Authority of the State of New York
(Represented by Uhl, Hall Rich)
H. E. Pierce, Jr.
New England Power Company
H. B. Smith
Niagara Mohawk Power Corporation
Assisted by the Working Group on

Studies of Improbable Events
H. B. Smith, Chairman
Niagara Mohawk Power Corporation
G. D.
Niagara Mohawk Power Corporation
J. R. Stewart
Niagara Mohawk Power Corporation
G. C. Loehr
Consolidated Edison Company of New York, Inc.
D. Hayward
New England Power Company
B. MacKenzie
New York State Electric and Gas Corporation
E. G. Neudorf
L. J. Rubino
The
Power Commission of Ontario
The
Power Commission of Ontario

Liaison
I
C. R. Jacobsen
Federal
Commission ii
OFFICERS
ERNEST R. ACKER
284 South Avenue
New York
F .
Room


New York, N. Y.
STER E. REYNOLDS

2 0 1 0
Hartford,
ERNEST I.. GROVE
Assistant Treasurer
Box 2010
Connecticut
M A S J . B R O S N A N
Chairman
Design
Committee
R O B E R T
Chairman
Operating Procedure
Committee
M A X M .
Relations
MEMBERS
Edison Compony
Hudson Gas Electric
Corporation

Power Company
al Vermont Public Service
Corporation
tight and Power
C o m p a n y
Edison Company
of New York, Inc.
tern Utilities Associates
en Mountain Power
Corporation
Electric light Company
Power Company
Power Commission


Electric System
gland

Electric
Association
State Electric Gas
Corporotion
Mohawk Power
and
Utilities, Inc.
Authority of the State of
New York
Service Company
New Hampshire
ster Gas and Electric
ted illuminating Company
Massachusetts Electric
NORTHEAST POWER COORDINATING COUNCIL
284 South Avenue, Poughkeepsie, New York

May

1966
Mr. F. S. Brown, Chief
Bureau of Power
Commission
Washington, D. C. 20426
Dear Mr. Brown:
In accordance with our recent discussion in
Washington, the Northeast Power Coordinating Council
is initiating studies of the northeast interconnected systems
to supplement the Phase I and Phase II studies of the FPC
System Studies Group under
1966
conditions. The Councils
studies will be conducted by its Task Force on System
Studies with membership as follows:
Name
Power System
William
Balet
Consolidated
Paul L. Dandeno
Ontario Hydro
E. Pierce, Jr.
New England Power
Harry
Smith
Niagara Mohawk
Einer Greve
Power Authority
Keith W. Amish, Chairman
Rochester G. E.
All of
of this task force are members of the
FPC System Studies Group.
The Council studies will deter
mine the effect of planned generation and transmission
additions through

on the most severe improbable
cases analyzed by the FPC System Studies Group.
The
following cases are being considered:
Case No.
1.71
Description
Three phase fault on one Niagara-Rochester
345 Kv circuit with one breaker at Niagara
failing to operate. Mr. F. S. Brown
May 13,
1966
Case No.
1. 72
8. 11
9.32
10.11
1.53
2.11
phase fault involving both Niagara-Rochester
345 Kv circuits with unsuccessful reclosing.
Three phase fault involving both Rochester-Clay 345 Kv
circuits with unsuccessful reclosing.
Three phase fault involving both Clay-Edit 345 Kv
circuits with unsuccessful reclosing.
Three phase fault causing loss of all transmission
circuits from
generating plant and breaker
at
failing to operate.
Three phase fault on two Beck 230 Kv circuits and one
breaker failing to operate, no delivery to Canada.
On Test 590-128, instability developed even though the
power flow relays operated to separate Canada from
New York.
This case will be rerun with the fault
detection relays at Packard and Niagara operating.
A test under 1968 conditions is contingent on the out-
come of this rerun.
Three phase fault involving all three
Hinchinbrooke 230 Kv circuits. A test under 1968
conditions is contingent on the investigation of
transient conditions under 1966 conditions by the
systems involved.
While the results of this series of tests will show the effect of genera-
tion and transmission additions, they will not include the effect of
other proposed changes, as for example, in protective devices, that
are now under study and may be made by 1968.
The Council will from time to time advise the Commission
as to the progress of these studies and upon their completion will
submit a report to the Commission setting forth the results.
It is our understanding that you have designated Mr.
Jerome K. Delson of your staff as your liaison representative for Mr. F. S. Brown
May 13,
1966
this project and we assume that he will contact Mr. Amish for any
information he may require in connection with this assignment.
With best regards,
Yours sincerely,
Ernest R.
Chairman

1.
The study was conducted to examine the response of the Northeast
Power interconnected systems following severe disturbances under
system conditions.
The
system representation included all major
generation and transmission additions planned for that time.
Tests have
been conducted similar to the severe possible but improbable events
reported in Section IV of the report to the Federal Power Commission,
Studies Related to the Northeast Power Interruption dated June 1,
A comparison of matching tests indicates the effect of the scheduled addi-
tions on the system response. INTRODUCTION
The System Studies Group appointed by the Federal Power Commission
was assigned two jobs: (1) to attempt to reproduce the initial events of
November 9, 1965 through the use of computer simulation, and (2) to examine
the Northeast interconnected systems for other events that could lead to a
similar widespread outage.
The Federal Power Commission System Studies
Groups June 1, 1966 report discusses the studies and results of these assign-
ments.
In section IV of this report covering the analysis of postulated major
disturbances referred to as possible, but improbable events, it was shown
that in some cases these events caused no major problems; in others, the
system was stable but overloads on underlying circuits might create a prob-
lem, and in some cases, instability could occur.
This report by the Northeas