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Frequency Response Initiative
Generator Event Survey
NERC Resources Subcommittee
North American Generator Forum
December 8, 2016
RELIABILITY | ACCOUNTABILITY2
• Essential for Reliability of the Interconnections Cornerstone for system stability
Line of defense to prevent Under Frequency Load Shedding(UFLS)
Prevent equipment damage
• Essential for System Restoration Droop response is critical in restoration efforts
Hydro units and gas turbines are some of the first units to be restarted
• Compliance with NERC Standards BAL-003-1, BAL-001 Mitigate future regulations related to generator frequency response
performance
• To accurately predict system events (Transmission Models)
Why Primary Frequency Response Is Important
RELIABILITY | ACCOUNTABILITY3
2012 Frequency Response Initiative Report
“Lazy L”
RELIABILITY | ACCOUNTABILITY4
NERC Outreach OEM and Engineering Firms
RELIABILITY | ACCOUNTABILITY5
• Advisory issued February 5, 2015
• Initiated by NERC Resource Subcommittee Interconnections frequency response
has declined
Eastern Interconnection Lazy L profile
2010 and 2013 Generator Survey Data
Generator Governor Frequency Response Advisory
Generator Governor Frequency Response Advisory
RELIABILITY | ACCOUNTABILITY6
Turbine OEM Reach Out to Customer Base
RELIABILITY | ACCOUNTABILITY7
Many Deadbands Exceed 36 mHz
• Deadbands Vary Many exceed 36 mHz or 2.16 RPM
• Droops Settings Vary Majority Droops reported 5%
What has been learned –Deadbands Exceed
RELIABILITY | ACCOUNTABILITY8
What has been learned –Outer Loop Control
Coordination with plant DCS is a requirement when operating in MW Set Point Coordinated Control.
RELIABILITY | ACCOUNTABILITY9
• Posted December 15, 2015
Reliability Guideline:Primary Frequency Control
1. Always present
2. Default on modern units
since ~2011
3. Site specific , co-ordination required
Primary response GE perspective 1. Basic governor always present. Used for startup, synch, over speed
protection and other functions in addition to droop
2. Unit level load control with primary frequency regulation bias. Default
on new units starting ~ 2011, also default on many retrofits to larger
units. May need to be disabled or coordinated with plant control.
3. Plant level load control. Plant –plant coordination with A/E. Open loop
vs closed loop, steam unit considerations, coordination with turbine
load controller etc. Simple algorithms, low or no cost in plant design
phase.
• Recommend Plant level primary frequency
response be a contractual requirement on new
plant so not change order mid-commissioning
• Clearly defined requirements ( ex. ERCOT 5.78%)
…also define what constitutes plant rated load (
ISO, prevailing ambient, supplemental sources etc)
• Example , minimum of X % response in Y seconds
for Z mHz change in frequency
• Requirements will trickle down to turbine supplier
• Plant level testing
• Must coordinate frequency injection
between systems
Recommendations
• Clearly defined requirements upfront save time and resources
Outer Closed Loop Controls
• Any closed-loop load controls can “squelch” or “negate” governor droop response (PFR)
• Must add a PFR bias or simulation component
• Subject to tuning:
– Proportional
– Integrating
• Outside controls usually executed at a slower scan rate (1 second)
RELIABILITY | ACCOUNTABILITY12
Illustration
Frequency 60.000 Hz
Graphic from GE info bulletin PSIB20150212
RELIABILITY | ACCOUNTABILITY13
Illustration
450 MW
Frequency 59.940 Hz
153 MW for little more than 1 second
150 MW
+/- Dead Band MW
153 MW for little more than 1 second
Graphic from GE info bulletin PSIB20150212
Mis
sin
g
RELIABILITY | ACCOUNTABILITY14
Example
450 MW
Frequency 59.940 Hz
153 MW
150 MW
+/- Dead Band MW
153 MW
456 MW
6 MW
Graphic from GE info bulletin PSIB20150212
RELIABILITY | ACCOUNTABILITY15
Example
400 MW
Frequency 60.000 Hz
150 MW
150 MW
100 MW
400 MW
0 MW
Graphic from GE info bulletin PSIB20150212
RELIABILITY | ACCOUNTABILITY16
Conventional Steam Plant
Graphic from GE info bulletin PSIB20150212
Frequency 59.940 Hz
400 MW6 MW
406 MW
+/- Dead Band MW
406 MW
RELIABILITY | ACCOUNTABILITY17
The Capability Goal
Reliability Guideline: Primary Frequency ControlIn order to provide Primary Frequency Control, it is recommended that all resources connected to an Interconnection be equipped with a working governor or equivalent frequency control device.
The primary focus of the Guideline is prime mover governors. Other forms of resources providing frequency response should have similar response characteristics described herein for governor.
3 -175 MW GE7FA Gas Mark VIe Turbine
Frequency Algorithm added to Plant DCS
RELIABILITY | ACCOUNTABILITY18
• Three Interconnections: Eastern, Western and Quebec conduct periodic generator surveys based on selected events over multiple years to measure generators individual performance. The surveys intention is to bring awareness to the industry and assist the
industry in improving primary frequency response. The purpose of this data collection is not related to compliance.
The NERC RS and NERC Staff will select at least two events a year spaced out in such a way to allow generator to address any issues discovered.
Surveys will be sent within a timely manner of selected frequency excursions.
Generator owners should complete and provide survey data for all BES generators online at the time of the event.
Next Step: Generator Survey
RELIABILITY | ACCOUNTABILITY19
• NERC will provide an email address and instructions for survey responses.
• Additional webinars with OEM and Engineering firms to provide resources to the industry.
Additional Details
RELIABILITY | ACCOUNTABILITY20
Generator Survey Form
RELIABILITY | ACCOUNTABILITY21
Generator Survey: Historian Data Entry
RELIABILITY | ACCOUNTABILITY22
Generator Survey: Results
RELIABILITY | ACCOUNTABILITY23
For Generators with headroom(between Pmin and 2% of Pmax),Generators who provide response in the proper direction and sustained it for the lesser of the event duration or for 1 minute.
Generators whose MW output remained unchanged, was in the wrong direction, or withdrew response.
Assessing Performance:Simplistic Grading System