NEPOOL Operating Procedure No. 12

VOLTAGE AND REACTIVE CONTROL

Approved:	July 22, 1998 by the NEPOOL Regional Market Operations Committee and the NEPOOL Regional Transmission Operations Committee to be implemented for the Second Effective Date for Market Implementation.
References:	
1.	ISO New England Transmission Operating Guides - All Voltage/Reactive Guides

2.	NEPOOL Operating Procedure No. 4 - Action During a Capacity Deficiency   (OP 4)

3.	NEPOOL Operating Procedure No. 7 - Action in an Emergency (OP 7)

4.	NEPOOL Operating Procedure No. 14  - Technical Requirements for Generation and Load (OP 14)

5.	NEPOOL Operating Procedure No. 16 - Transmission System Data (OP 16)

6.	NEPOOL Operating Procedure No.19 - Transmission Operations (OP 19)

7.	Master/Satellite Procedure No. 9 - Operation of the Chester Static VAR Compensator    (M/S 9)

TABLE OF CONTENTS
					   
I.	INTRODUCTION	3

II.	CRITERIA	3
A.	Voltage Schedules and Limits for Generators and Key Transmission Stations	3
B.	Generator Reactive Capabilities, Commitments and Required Reactive Reserves	4

III.	VOLTAGE/REACTIVE OPERATING PRACTICES	4
A.	Traditional Voltage/Reactive Control	4
B.	Circuit Switching to Control High Voltage	4
C.	Load Management for Voltage/Reactive Reliability	4

IV.	RESPONSIBILITIES	4
A.	Generating and Transmission Stations	4
B.	Satellites	5
C.	ISO NEW ENGLAND	6

APPENDIX
A. 	Voltage/Reactive Documents in the ISO New England Transmission Operating Guides

B. 	Voltage and Reactive Survey 

I.	
INTRODUCTION

This procedure provides broad criteria, operating practices and responsibilities to help ensure that desired/reliable voltage and reactive conditions are maintained on the power system.  It also includes general actions to control voltage/reactive conditions when deviations from normal occur or are needed to minimize adverse effects during abnormal conditions. 

More specific criteria and actions may be required when the measures described in this procedure do not correct the abnormal voltage/reactive conditions.  This information is contained in detailed voltage/reactive documents issued as part of the ISO New England Transmission Operating Guides.  Whereas these guides are referenced several times throughout this procedure, Appendix A lists the documents and indicates the types of information they contain.  To facilitate references to Appendix A, its column numbering and headings are consistent with the format and order of this procedure.

II.	CRITERIA

A.	Voltage Schedules and Limits for Generators and Key Transmission Stations

Major generating stations throughout New England have specified voltage schedules, which should be maintained as closely as possible in system operations.  They should also be used by operators and planners in off-line studies of the power system.  During certain conditions at a generating station or on the power system, sustained deviations from voltage schedules may be required/unavoidable and minimum and maximum voltages have been established that can be sustained at generating stations during these infrequent conditions.

In addition to voltage schedules, minimum and maximum voltage limits at several key generating or transmission stations have been established to promote system reliability during adverse voltage/reactive conditions.  These reliability concerns can be based on the security of the transmission system or station service supplies to nuclear generators.  The key stations and associated voltage limits are detailed in the area Voltage Guides issued as part of the ISO New England Transmission Operating Guides (refer to Appendix A, column 1). 

B.	Generator Reactive Capabilities, Commitments and Required Reactive Reserves

Generator reactive capabilities available to regulate voltages should be employed in system operations and analyses.  Data collection methods (see OP 14) have been designed such that these reactive capabilities should be fully available except for occasional times when unique temporary problems occur at a particular generating station.
To promote security of the transmission system during adverse voltage/reactive conditions, required unit commitments and levels of required reactive reserve for generators within certain areas of New England and for the Chester SVC have been established.  System conditions that warrant the prescribed unit commitments or reactive reserves have also been identified.  Details are provided in the ISO New England Transmission Operating Guides (see Appendix A columns 2 and 3).

III.	VOLTAGE/REACTIVE OPERATING PRACTICES

A.	Traditional Voltage/Reactive Control	

Besides the use of generator reactive capabilities, the proper dispatch of shunt capacitors/reactors combined with effective transformer voltage schedules or fixed tap settings are the most traditional means of achieving desired voltages and reactive conditions.  Listings of switchable shunt devices installed to support the New England transmission system (115 kV and above) and guides for switching them can be found in the area Voltage Guides (see Appendix A, column 4).  

B.	Circuit Switching to Control High Voltage

In some areas, transmission circuit switching is a viable option for controlling high voltage/excessive charging conditions.  Appendix A column 5 identifies the ISO New England Transmission Operating Guides that provide information for switching circuits in the Boston area to control high voltage.

C.	Load Management for Voltage/Reactive Reliability

In severe cases of low voltage and/or inadequate reactive reserves, load management actions can be taken.  Details on conditions when these actions can/should be used and how they should be implemented are provided in the Voltage Guides (as identified in Appendix A, column 6) and NEPOOL Operating Procedures No. 4 and 7.

IV.	RESPONSIBILITIES

This procedure is based on the principle that voltage control is best achieved when action is taken as close as possible to the affected area.  Voltage schedules and other reactive conditions will be supervised by Station, Satellite and the ISO operators, each being responsible for an ever expanding area of responsibility.  Regardless of who's requesting or directing corrective measures, action must ultimately be taken by Station or Satellite operators depending on who has "hands on" control of the reactive resources.

A.	Generating and Transmission Stations

Generating and transmission station operators are responsible for maintaining station service and other local voltage requirements and scheduled voltages at levels designated by individual Participants.  Generating stations are also responsible for maintaining voltage schedules set for the high side of the generator step-up transformers by the appropriate NEPOOL committee.  Normally, automatic voltage regulation works off the low side of the step-up transformer (generator terminals).  Thus, in order to maintain a high side voltage schedule, manual intervention can be required to offset varying power flows through and voltage drops across the step-up transformer. 

When unable to maintain scheduled station and local voltages with the means under their control, the generating or transmission station operators should notify their respective Satellite operator (and local dispatch authority if appropriate).

B.	Satellites

Satellites are responsible for monitoring and supervising the following conditions within their territories:

•	voltage schedules and limits,
•	unit MVAR loadings, capabilities and reserves,
•	shunt capacitor and reactor dispatches,
•	transformer voltage schedules or fixed tap settings,
•	synchronous condenser operation,
•	MVAR flows between the AC system and HVDC facilities,
•	Static VAR Compensator operation (must be coordinated with the ISO),
•	line switching for voltage/reactive control (must be coordinated with the ISO and, if warranted, with other Satellites),
•	the Satellites will notify/ coordinate the need for MW re-dispatch for MVAR requirements with the ISO.  The Satellites will not directly re-dispatch MW with generators unless it is an emergency,
•	other predefined indicators of voltage/reactive security (e.g. a particular circuit flow, the status of specific units, area load level, etc.).

Satellites are responsible for: 1) detecting and correcting deviations from normal scheduled voltage/reactive operations, 2) responding to notifications by generating or transmission station operators of difficulty in maintaining station or other local voltage or reactive schedules and, 3) responding to ISO requests to assist with inter-Satellite or inter-Area problems.

Satellites are authorized to exercise the following actions to correct voltage/reactive difficulties within their territories: 

•	direct voltage schedules and levels of reactive output and reserve on generators, synchronous condensers and Static VAR Compensators,
•	direct the use of shunt capacitors and reactors,
•	direct the operation of LTC transformers.

When a Satellite is unable to correct a voltage/reactive problem using the above actions or the Satellite believes that the problem should be handled on a multi-Satellite or inter-Area basis, the Satellite will notify the ISO and request assistance.

Before exercising any of the following voltage/reactive control actions, Satellites must notify the ISO and coordinate their implementations:

•	line switching,
•	load management.

C.	ISO NEW ENGLAND

The ISO is responsible for the general monitoring and supervision of voltage/reactive conditions on the New England bulk power system (115 KV and above).  If in monitoring the system a problem is detected within a Satellite, the ISO will contact the Satellite and request action.

When a Satellite reports to the ISO that it is not possible to correct a problem at a station or Satellite level, the ISO will assume direct responsibility for alleviating the problem.  The ISO is authorized to direct, through the appropriate Satellite(s), all actions listed in the above Satellite section B and in addition any MW re-dispatching.

The ISO is also responsible for monitoring and supervising voltage/reactive operations of inter-Area ties.  Problems may be noticed by the ISO or appear in the form of requests from neighboring pools or companies for assistance.  The ISO will inform the appropriate Satellite(s) of the nature of the problem specifying; the pool or company involved, the location of the undesirable voltage/reactive condition and, general conditions aggravating the difficulty.  The ISO is authorized to work with/through the Satellites and use all section B actions and MWh re-dispatching to eliminate the problem. 

When abnormal voltage/reactive operating conditions materialize, the ISO may initiate a survey of key system parameters to better assess the nature and expanse of the conditions.  Appendix B contains the survey forms that the ISO will use.  The forms are broken down based on Satellite territories.

Document History

OP 12.rtf
8/18/98

	Voltage/Reactive Documents in the ISO New England Transmission Operating Guides
   
                                    1         2                3            4             5               6                 		                                                                                             Load
Voltage/Reactive Document	           Voltage   Req'd Unit	    Req'd. Reactive   Shunt         Line Switching    Management
                                      Limits   Commitments         Reserves     Information    For High Voltage     Actions

Eastern REMVEC Low Voltage Guide         ü                            ü             ü                                 ü

Low Voltage Guidelines-Connecticut       ü                            ü             ü                                 ü
345 KV System

Northern New England Transmission        ü                                          ü                                 ü
Corridor-Low Voltage Guide

Northern New England Transmission        ü          ü                               ü
Corridor - High Voltage Guide

Orrington Capacitors                     ü                                          ü                

Southern Connecticut Voltage             ü                                          ü 
Guidelines

Connecticut						     ü
Forecasting and Operating Guideline

Must Run Units/Conditions in the Boston Area	     ü                                  

Method to Ensure Reliable "All Lines In"            ü                               ü
Voltage/Reactive Operation in VT

Operation of the Boston Edison                                                      ü
Tertiary Reactors

Boston Area Voltage Control - Light Load										 ü

Switching Guidelines for Line 372                                                                    ü                             (Voltage Control)

Operations Guide for 349 Cable                                                                       ü
Switching

M/S-9 Operation of the Chester SVC       ü                            ü            				

Voltage and Reactive Survey

					    REMVEC								
	VOLT												
	SCHED	VOLT			STATIONS/LINES	VOLT	VOLT			CAPACITORS/			
UNITS	HVY/LGT	ACTUAL	MVARS		TRANSFORMERS	SCHED	ACTUAL	MVARS		REACTORS	AVAIL	MVARS	
BRAYTON 1	118/116				COOLIDGE XF					BAKER ST	107		
BRAYTON 2	118/116				GRANITE XF					FRAMINGHAM	54		
BRAYTON 3	358/352				KINGSTON XF					LEXINGTON	54		
BRAYTON 4	358/352									K ST	107		
CANAL 1	358/355									MYSTIC	54		
CANAL 2	358/355									NEEDHAM	54		
MYSTIC 4	119/117									WOBURN REACT	-80		
MYSTIC 5	119/117									N. CAMBRIDGE REACT	-102		
MYSTIC 6	119/117									MYSTIC REACT	-80		
MYSTIC 7	360/352									MILLBURY	63		
NEA BELLINGHAM	358/352									PRATTS	63		
NEW BOSTON 1	119/117									KENT COUNTY	63		
NEW BOSTON 2	119/117									TEWKSBURY	126		
SALEM HARBOR 3	119/117									FRANKLIN SQ	63		
SALEM HARBOR 4	119/117									ESSEX	50		
OCEAN STATE 1	355/350									SANDBAR	25		
OCEAN STATE 2	355/350									WILLISTON	25		
SOMERSET 6	116/115									MIDDLEBURY	23		
BEAR SWAMP 1	234/230									N. RUTLAND	24		
BEAR SWAMP 2	234/230									BERLIN	24		
PILGRIM	358/358									EAST FAIRFAX	24		
CLEARY CC	118/116									HYANNIS	40		
MILFORD POWER	115/115									COMERFORD 451			
MOORE	240/225									COMERFORD 452			
COMERFORD	240/225									SANDY PD 3512			
VERMONT YANKEE	360/354									SANDY PD 3521			
Notes:  Transformers: (+) denotes flow into low side    (-) denotes flow into high side	

					CONVEX								
	VOLT												
	SCHED	VOLT			STATIONS/LINES	VOLT	VOLT			CAPACITORS/			
UNITS	HVY/LGT	ACTUAL	MVARS		TRANSFORMERS	SCHED	ACTUAL	MVARS		REACTORS	AVAIL	MVARS	
BRIDGEPORT HBR 2	118/117				BERKSHIRE 345					EAST SHORE	84		
BRIDGEPORT HBR 3	118/117				BERKSHIRE 115					SACKETT	42		
DEVON 7	118/117				BERKSHIRE XF					NORTH HAVEN	42		
DEVON 8	118/117				ALPS-BERK 393					MANCHESTER	314		
MIDDLETOWN 2	118/116				FROST BRIDGE 345					BERLIN	119		
MIDDLETOWN 3	118/116				FROST BRIDGE 115					N. BLOOMFIELD	157		
MIDDLETOWN 4	360/359				FROST BRIDGE XF					GLENBROOK	191		
MILLSTONE 1	357/357				PL VLY-LNG MT 398					FROST BRIDGE	157		
MILLSTONE 2	357/357				LUDLOW 345					PLUMTREE	80		
MILLSTONE 3	357/357				LUDLOW 115					NORWALK HBR	79		
MASS POWER	117/117				LUDLOW 1X XF					AGAWAM	104		
MONTVILLE 6	117/117				LUDLOW 3X XF					MONTVILLE	105		
MOUNT TOM	115/115				MANCHESTER 345					SOUTHINGTON	157		
NORTHFIELD G1	359/359				MANCHESTER 115					DARIEN	40		
NORTHFIELD G2	359/359				MANCHESTER 4X XF					WATERSIDE	40		
NORTHFIELD G3	359/359				MANCHESTER 5X XF								
NORTHFIELD G4	359/359				MANCHESTER 6X XF								
NORTHFIELD P1	351/351				MONTVILLE 345								
NORTHFIELD P2	351/351				MONTVILLE 115								
NORTHFIELD P3	351/351				MONTVILLE 18X XF								
NORTHFIELD P4	351/351				MONTVILLE 19X XF								
NORWALK HBR 1	119/119				NWK HBR-NPRT 1385								
NORWALK HBR 2	119/119				PLUMTREE 345								
NEW HAVEN HBR	119/117				PLUMTREE 115								
WEST SPFLD 3	116/116				PLUMTREE 1X XF								
ALTRESCO	117/117				PLUMTREE 2X XF								
BRIDGEPORT ENERGY	118/117				SOUTHINGTON 345								
AES THAMES	117/117				SOUTHINGTON 115								
					SOUTHINGTON 1X XF								
					SOUTHINGTON 2X XF								
					SOUTHINGTON 3X XF								
					SOUTHINGTON 4X XF								
Notes:  Transformers: (+) denotes flow into low side    (-) denotes flow into high side	

					MAINE / PSNH								
	VOLT												
	SCHED	VOLT			STATIONS/LINES	VOLT	VOLT			CAPACITORS/			
UNITS	HVY/LGT	ACTUAL	MVARS		TRANSFORMERS	SCHED	ACTUAL	MVARS		REACTORS	AVAIL	MVARS	
YARMOUTH 3	120/120									CHESTER SVC CAP	442		
YARMOUTH 4	355/355									CHESTER SVC REAC	-124		
MERRIMACK 1	119/119									ORRINGTON CAP #1	67		
MERRIMACK 2	119/119									ORRINGTON CAP #2	67		
NEWINGTON	357/357									ORRINGTON CAP #3	67		
SCHILLER 4	119/119									ORRINGTN REACT #1	-40		
SCHILLER 5	119/119									ORRINGTN REACT #2	-40		
SCHILLER 6	119/119									MAINE YANKEE	30.6		
SEABROOK	357/357									SUROWIEC REACT #1	-40		
										SUROWIEC REACT #2	-40		
										BEEBE	20		
										MERRIMACK 1	37.5		
										MERRIMACK 2	37.5		
										SCOBIE REACT	-80		

													

													

													

													

Notes:  Transformers: (+) denotes flow into low side    (-) denotes flow into high side