NEPOOL OPERATING PROCEDURE NO. 13
 
STANDARDS FOR VOLTAGE REDUCTION AND
LOAD SHEDDING CAPABILITY

Approved:	August 20, 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:

North American Electric Reliability Council (NERC)		
Operating Guide No. 11					Load Shedding and Restoration

Northeast Power Coordinating Council (NPCC)		Emergency Operation Criteria (A‑3)

NEPOOL Operating Procedure No. 4		Action During a Capacity Deficiency

NEPOOL Operating Procedure No. 7				Action in An Emergency 

NEPOOL Operating Procedure No. 8	Operating Reserve and Automatic Generation Control

NEPOOL Operating Procedure No. 14	Technical Requirements of Generation and Load

Master/Satellite Procedure No. 2				Abnormal Conditions Alert

Market Rules and Procedures

Table of Contents

I.	INTRODUCTION	3

II.	COMPLIANCE	3

III.	REQUIREMENTS	4
A.	Voltage Reduction	4
B.	Load Shedding	5

IV.	COMPLIANCE SURVEYS	6

V.	TESTING	7
A.	Voltage Reduction	7
B.	Load Shedding	7

Appendix A - Holidays Applicable to Voltage Reduction Capability
I.	
INTRODUCTION

This document establishes standards for the installation and testing of Participants with control over transmission/distribution facilities voltage reduction and load shedding capability.  These standards require that all NEPOOL Participants with control over transmission/distribution facilities have the capability to reduce load demand when directed to do so for bulk power supply dispatching purposes.  These load reducing capabilities are used by the ISO and/or the Satellites to maintain system reliability during generating capacity deficiencies, energy deficiencies, and other emergency operating conditions as described in NEPOOL Operating Procedure No. 4 ‑ Action During a Capacity Deficiency (OP 4) and NEPOOL Operating Procedure No. 7 ‑ Action in an Emergency (OP 7).

II.	COMPLIANCE

Participants with control over transmission/distribution facilities are expected to comply with the standards established by this NEPOOL Operating Procedure.  Those not in compliance are expected to proceed immediately to achieve compliance.

Participants with control over transmission/distribution facilities may achieve compliance by arranging with another Participant with control over transmission/distribution facilities to provide on its behalf, voltage reduction and/or load shedding capability.  The voltage reduction and/or load shedding capability provided by such arrangements must be in a similar electrical location to the Participant for which service is provided.  Such arrangements must yield equivalent support to transmission system load and voltage as would be obtained if the Participant with control over transmission/distribution facilities had installed voltage reduction and load shedding capability on its own system.

Arrangements may also be made for one (1) Participant with control over transmission/distribution facilities to provide voltage reduction and/or load shedding capability for another Participant with control over transmission/distribution facilities during a portion of the day or week.  For example, a Participant with control over transmission/distribution facilities not able to reduce voltage or shed load during the entire period of time that such capability is required may arrange for another Participant with control over transmission/distribution facilities, subject to the requirements of the previous paragraph, to provide such capability on its behalf during the deficient periods.   Participants providing voltage reduction and/or load shedding capability for another Participant with control over transmission/distribution facilities must not count the capability dedicated to another Participant with control over transmission/distribution facilities toward meeting its own requirements.  

The details of arrangements between Participants with control over transmission/distribution facilities for voltage reduction and/or load shedding services to meet the standards of this NEPOOL Operating Procedure must be submitted to and approved by the NEPOOL Regional Market Operations Committee and the NEPOOL Regional Transmission Operations Committee.

III.	REQUIREMENTS

A.	Voltage Reduction

1.	Voltage reduction should take place on the distribution system wherever possible.  It is recognized that in certain areas, voltage reduction is implemented on the subtransmission system.  Voltage reduction should not be implemented on the transmission system operating at 69 KV and above.

2.	Ideally, voltage reduction capability should be installed so that all loads are subject to a five- (5) percent voltage reduction.  However, it is recognized that it may not be practical to subject some loads to voltage reduction (e.g., loads served from the transmission system, voltage sensitive loads, etc.).  It may be desirable to subject some loads to a voltage reduction of less than five (5) percent.  However, each Participant with control over transmission/distribution facilities must have the capability to reduce system load demand at the time a voltage reduction is initiated by at least one and one‑half (1.5) percent through implementation of a voltage reduction.

3.	It is intended that voltage reductions be fully implemented within ten (10) minutes from the time ordered.  However, it is recognized that it may not be practical for some Participants with control over transmission/distribution facilities to meet this requirement.  In those circumstances, voltage reduction which can be implemented in thirty (30) minutes is permissible.

4.	Each Participant with control over transmission/distribution facilities must be able to implement a voltage reduction on all non‑holiday weekdays during the period between 0800 to 2300 hours.  Holidays are those listed in Appendix A to this procedure.

5.	Upon application to and approval by the NEPOOL Regional Market Operations Committee and the NEPOOL Regional Transmission Operations Committee, the requirement for voltage reduction capability may be satisfied by an equivalent amount of interruptible loads.  Such loads must be interruptible within ten (10) minutes of issuance of the voltage reduction order by the ISO.  Loads designated for this purpose must be dedicated to NEPOOL Operating Procedure No. 4 (OP 4) ‑ Action During a Capacity Deficiency, must be under dispatch authority of the ISO and/or the appropriate Satellite, and do not qualify as NEPOOL Interruptible Loads under the provisions of NEPOOL Operating Procedure 14 (OP 14) - Technical Requirements of Generation and Load.

B.	
Load Shedding

1.	Each Participant with control over transmission/distribution facilities  must install underfrequency load shedding equipment to accomplish the following in an emergency characterized by rapid frequency decline:

•	Automatic load shedding of ten (10) percent of load initiated at a nominal set point of 59.3 Hertz.

•	Automatic load shedding of an additional fifteen (15) percent of load initiated at a nominal set point of 58.8 Hertz.

These load shedding steps are designed to return frequency to at least 58.5 Hertz in ten (10) seconds or less and to at least 59.5 Hertz in thirty (30) seconds or less, for a generation deficiency of up to twenty‑five (25) percent of the load.
	
Load shed automatically by underfrequency relays shall not be automatically restored.

2.	Each Participant with control over transmission/distribution facilities must be capable of manually shedding at least fifty (50) percent of load in ten (10) minutes or less.  Insofar as practical, the first half of the load shed manually should not include that load which is part of any automatic load shedding plan (III.B.1. above).

3.	Manual load shedding should not interrupt transmission paths.  Participants with control over transmission/distribution facilities who include such interruptions in load shedding plans must demonstrate from system simulations that transmission interruptions will not degrade interconnected system reliability.

4.	Manual load shedding plans may incorporate the use of digital pager systems, outside of normal business hours, to notify Participants with control over transmission/distribution facilities personnel that manual load shedding has been requested.  Participants with control over transmission/distribution facilities whose plans include the use of such a system must coordinate those plans with the appropriate Satellite Control Center.  In addition, Participants with control over transmission/distribution facilities whose plans include use of a pager system will consider receipt of an Abnormal Conditions Alert, under Master/Satellite Procedure #2 - Abnormal Conditions Alert, as notification that their substations are to be staffed for possible implementation of manual load shedding during the period that the Alert is in effect.

This provision for the use of a digital display pager system is subject to review by the NEPOOL Regional Market Operations Committee and the NEPOOL Regional Transmission Operations Committee relative to the overall manual load shedding capability of NEPOOL and the extent to which such systems are being used to provide coverage outside of normal business hours.  The compliance surveys performed in accordance with Section IV of this NEPOOL Operating Procedure will serve as the basis for such NEPOOL Regional Market Operations Committee and the NEPOOL Regional Transmission Operations Committee reviews.

5.	The plan should include the capability of shedding load proportionately over the whole system; however, it is recognized that this may not be practical in some areas.

Generation connected to sub‑transmission or distribution systems will have an ever‑increasing impact on load shedding plans.  If such a resource is interrupted as part of a Participant with control over transmission/distribution facilities load shedding plan, an equivalent amount of additional load must be included in the load shedding plans.

6.	Each Participant with control over transmission/distribution facilities must be capable of implementing automatic and manual load shedding twenty‑four (24) hours a day.

7.	Once manual load shedding has been implemented, the appropriate Satellite will inform the Participants with control over transmission/distribution facilities of the estimated length of time that the load is expected to be interrupted.  Depending on the time estimate, Participants with control over transmission/distribution facilities may choose to initiate feeder rotations.  During the rotation process, load must be interrupted before an equivalent load can be restored.

IV.	COMPLIANCE SURVEYS

The ISO will survey each Participant with control over transmission/distribution facilities to verify voltage reduction and load shedding capability.  Such surveys will be conducted at least once every five- (5) years and at most once each year.  In addition, a new Participant with control over transmission/distribution facilities will be required to complete a survey within 30 days after becoming a NEPOOL Participant.

The purpose of the surveys is to assess the Participants with control over transmission/distribution facilities compliance with the requirements of this procedure.  A report will be issued to the NEPOOL Regional Market Operations Committee and the NEPOOL Regional Transmission Operations Committee identifying Participants with control over transmission/distribution facilities found not to be in full compliance and summarizing the areas of deficiency.  Each such Participant with control over transmission/distribution facilities shall, within 30 days following the NEPOOL Regional Market Operations Committee and the NEPOOL Regional Transmission Operations Committee's review of the survey results and on October 1 of each year thereafter, issue a written report to the NEPOOL Regional Market Operations Committee and the NEPOOL Regional Transmission Operations Committee detailing plans for and progress towards compliance along with dates that compliance is expected.  In addition, each non-compliant Participant with control over transmission/distribution facilities is required to complete and submit a new survey to the ISO on October 1 each year until compliance is achieved.

V.	TESTING

A.	Voltage Reduction

At the discretion of the NEPOOL Regional Market Operations Committee and the NEPOOL Regional Transmission Operations Committee, the ISO will conduct system‑wide voltage reduction tests. An actual voltage reduction will be implemented.  Participants with control over transmission/distribution facilities will record the load reduction attained within ten (10) minutes and/or thirty (30) minutes in the test.  If such records are not possible, Satellite load relief data may be used.  Each Participant with control over transmission/distribution facilities will complete a questionnaire that will record load relief attained and identify operational, or customer, problems that were encountered and should be resolved.  The data will be used by the ISO to update load relief estimates contained in NEPOOL Operating Procedure No. 4 ‑ Action During a Capacity Deficiency, and to help verify each Participant’s with control over transmission/distribution facilities voltage reduction capability.

Voltage reduction tests will be conducted in accordance with the following parameters:

1.	A date will be established for the test.

2.	Participants with control over transmission/distribution facilities will be given a written notice four (4) weeks in advance of the test date.

3.	If system-operating conditions force cancellation of the test, a new date will be set in accordance with the above parameters.

4.	Voltage reduction load relief capability shall be measured by each Participant with control over transmission/distribution facilities during system‑wide voltage reduction tests.

B.	Load Shedding

Every second month, the ISO will conduct a simulated manual load shed test to train the ISO, Satellite, and Participant with control over transmission/distribution facilities personnel in all aspects of manual load shedding procedures.  These tests will be conducted in accordance with NEPOOL Operating Procedure No. 7 (OP 7) ‑Action in an Emergency, to the maximum extent possible. Tests will deviate from actual load shed operations in the following manner.

1.	All verbal load-shedding directives will be preceded and concluded with the statement, "This is a test.  Do not shed load".

2.	Operators will not open breakers or disconnect actual load, but instead, will observe or estimate the amount of load that would have been shed on the circuit had it been an actual load shedding operation.  These tests may be used to help verify a Participant with control over transmission/distribution facilities's capability to reduce system load by as much as fifty (50) percent.

3.	Operators will report the amount of load that would have been shed and the length of time to do it to their next highest dispatching authority.  The ISO will issue reports on each simulated manual load shedding test.  The report will specify the amount of load relief attained and the time interval to attain the load shed during the test.

Document History

	STANDARDS FOR VOLTAGE REDUCTION AND
	LOAD SHEDDING CAPABILITY

	Holidays Applicable to Voltage Reduction Capability

				New Year's Day

				Memorial Day

				Independence Day

				Labor Day

				Veterans Day

				Thanksgiving Day

				Christmas Day