Balancing Electricity Focus on Operational Management ...
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Balancing Electricity – Focus on Operational Management/ Frequency control Julia Matevosyan Lead Planning Engineer, Resource Adequacy dena-symposium A Global Perspective on Electricity Ancillary Service Berlin, November 2018
Transcript of Balancing Electricity Focus on Operational Management ...
Balancing Electricity – Focus on
Operational Management/ Frequency
control
Julia Matevosyan
Lead Planning Engineer, Resource Adequacy
dena-symposium
A Global Perspective on Electricity Ancillary
Service
Berlin, November 2018
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Outline
• What is ERCOT
• Wind and Solar Generation Capacity Charts
• ERCOT Compared to Other Systems
• Brief ERCOT Market Overview
• Primary Frequency Response Requirement
• Ancillary Services
• Load Participation in AS
• Key Takeaways
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What is ERCOT
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The interconnected electrical system serving most of Texas, with limited external connections
• 90% of Texas electric load; 75% of Texas land
• 73,308 MW peak demand, July 19, 2018
• 570+ generation units
ERCOT connections to other grids are limited to ~1,250 MW of direct current (DC) ties, which allow control over the flow of electricity
600 MW with SPP
30 MW with CFE
at Eagle Pass
100 MW with CFE
at Laredo 300 MW with CFE at McAllen
220 MW with SPP
Texas RE
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ERCOT Energy Use and Generation Capacity
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Wind Generation Capacity – September 2018
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Future outcomes uncertain
Installed Wind Capacity: 21,190 MW
Wind Generation Record (instantaneous):
Output: 17,541 MW
‒ Feb. 19, 2018, 10:05 p.m.
Penetration (load served): 54%
‒ Oct. 27, 2017, 4 a.m.
‒ Total Load = 28,416 MW
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Utility Scale Solar Generation Capacity – September 2018
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Future outcomes uncertain
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SouthAustralia
Eirgrid HydroQuebec
Nordic TSOs ERCOT NG UK
Minumum Inertia Encountered (GW·s)
Min (GWs)
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ERCOT NG UK HydroQuebec
NordicTSOs
SouthAustralia
Eirgrid
Largest Contingency (MW)
Under-frequency side
ERCOT vs other systems with similar frequency control
challenges
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Source: Survey on Inertia Related Challenges and Mitigation Measures, presentation
at Wind Integration Workshop 2017
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Nodal energy Market, 5-min Real Time Dispatch
• Voluntary Day-Ahead Market (DAM); Ancillary Services are procured in
DAM, co-optimized with energy
• Generator self-commitment; ERCOT makes residual reliability commitments
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• All generators (including renewables)
submit offers for generation output
• Real-Time market clears every five
minutes, using the cheapest generation
to serve the load, subject to
transmission constraints.
• All generators (including renewables)
receive output level instructions and
locational marginal prices
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Primary Frequency Response (PFR) from All Generators
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59,85
59,875
59,9
59,925
59,95
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60,025
60,05
13:25 13:28 13:31 13:34 13:37 13:40
Wind Resource Response to Low Frequency 07/13/2016
Frequency Nominal Frequency MW
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59,925
59,944
59,963
59,981
60,000
60,019
60,038
60,056
60,075
16:13 16:16 16:19 16:22 16:25 16:28
Wind Resource Response to High Frequency 08/25/2015
Frequency Nominal Frequency MW
• All Generators (excl. nuclear) in ERCOT are required to provide PFR with ±17
mHz deadband and 5% droop. Capacity reservation is not required, unless
providing AS.
• Requirement for all wind and solar resources with interconnection agreements
after 2008 to provide PFR (about 2000 MW of older plants are exempt);
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Ancillary Services
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Regulation Up
157 to 687 MW*
Non-Spin967 to 2,361 MW
Responsive
Regulation Down
156 to 604 MW
1.Primary Frequency Response
2.Load Resources on Under Frequency
Relays (UFR)
2,300 to 3,200 MW
*The numbers are showing 2018 AS amounts
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Regulation (Up and Down)
• Provided from selected generators that
receive AGC signal from ERCOT every 4
seconds to move up or down to maintain
frequency between 5-minute dispatch
intervals;
• Requirement varies by hour of the day
and month based on historic 5-min net
load* variability.
*Net Load = Load – Wind – Solar
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Ancillary Services – Non-Spin
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• Used to ensure sufficient capacity is
available to cover net load forecast
errors or replace deployed frequency
containment reserve
• 30 min deployment required but
mostly provided by 10 min quick
start or unloaded on-line
generation
• Quantity required varies by time of
the day and season based on
historic forecast error and risk of
large net load ramps
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Responsive Reserve Service (RRS)
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• Used to ensure sufficient capacity is
available to respond to frequency
excursions due to unit trips
− Capacity reserved from
generators to provide RRS
through governor response
− Up to 60% of Responsive
requirement can be provided by
Loads with underfrequency relays
that trips at 59.7 Hz
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Inertial Effect
Initial rate of change of frequency
(prior to any resource response) is
solely a function of inertia
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Required RRS varies with Inertia
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Prim
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Fre
quency R
esponse(M
W)
Inertia (GW∙s)
RRS Requirement if provided by Generators Primary Frequency Response(MW)
5/17/2017 UVIG
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Varying Responsive Reserve Requirement
165/17/2017 UVIG
Using Load Resources (with underfrequency
Relays) to provide 60% the RRS, decreases the
total RRS MW requirement at lower inertia levels
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Load Resources Providing RRS
Single site loads (no aggregation), 100-250 MW:
• Industrial process plants that produce chemicals, each site >150 MW, and
consist of several process lines each about 50 MW.
• Air separation plants that extract industrial gasses, each site ≤ 100 MW
• Natural gas compression sites that are part of pipeline operation
• Oil field loads (from couple of kW to tens of MW),
• Industrial process loads (i.e. cement plants, manufacturing plants),
• Very few large commercial sites, mainly data centers.
The participation from broader range of customers is limited due to:
• Instantaneous interruption that a Resource should be able to withstand and
• Costs of real time telemetry equipment (a requirement for participation is to
add dedicated communication systems to send site data to ERCOT).
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Load Resources Providing RRS
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17011824
1975
2114 2136
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June2006
June2007
June2008
June2009
June2010
June2011
June2012
June2013
June2014
June2015
June2016
Load Resource MW registered
Deployed as Responsive Reserves, via:
• Manual dispatch, 10-minute ramp requirement
• Instantaneous trip via Under-Frequency Relay
Procurement capped at 60% of RRS
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Load Resources Providing RRS
• Currently over 300 Load Resources registered with total capacity of about
4200MW
• Participation rates are 1600-1700 MW of offers and about 1400 MW of awards
every day
• To participate in RRS, a Load Resource must go through a qualification test
with ERCOT.
• Biannual relay testing of registered resources or a recent event is used in lieu
of the test.
• ERCOT uses nearest PMU or high speed recorder data to verify Load
Resource performance after an event.
• The frequency trigger for Load Resources is set relatively low (for really large
events), they respond only one or two times a year, while carrying the reserve
and being paid for it every hour of the year.
• As system inertia is decreasing this may change and they’ll be triggered more
often.
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Reliability Risk Desk, Situational Awareness
Inertia Monitoring and Forecasting
Critical Inertia alerts
Reserve Sufficiency Monitoring
Overall Capacity Availability Tool
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Current Framework
Proposed Ancillary Service Framework Changes, 2018
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NPRR 863 With STEC Comments (4/26, 8/2) and ERCOT Steel Suggestions
Load Resources on UFR
Primary Frequency Response (PFR)
Fast Frequency Response (FFR)
ERCOT Contingency Reserve
Service (ECRS)
Load Resources
may or may not be on UFR
10 minute ramp
Responsive Reserve Service
1. Primary Frequency
Response
2. Load Resources on Under
Frequency Relay (UFR)
3. 10 minute ramp
2,300 to 3,200 MW*
No ChangeRegulationRegulation
157 to 687 MW* 157 to 687 MW*
2,300 to 3,200 MW*
508 to 1,644 MW**
Responsive Reserve Service (RRS)
Non-Spin
Non-Spin967 to 2,361 MW*
0 to 1,180 MW*
*Quantities computed/estimated using 2018 Ancillary Service Methodology. **Quantities estimated using this reference.
For Discussion Purposes Only. The intent of this slide is to represent NPRR 863 (with ERCOT comments from 7/6/2018). Protocol language prevails to the extent of any inconsistency with this one page summary.
Overall A/S: 3,807 to 5,958 MW* Overall A/S: 3,807 to 5,958 MW*
Last Edited on /16/2018
FFR
• Triggered at 59.85 Hz and full response in 15 cycles
• Once deployed, sustain for up to 15 mins. Once recalled, restore within 15 mins
PFR
• PFR capable capacity reserved on generators or Controllable Load Resources
(CLR)
• Minimum 1,150 MW must be provided by resources capable of PFR
Load Resources on UFR
• Triggered at 59.70 Hz and full response in 30 cycles
• Sustain until recalled. Once recalled, restore within 3 hours
• Beyond the minimum PFR, up to 60% of total FRS can come from Load
Resources on UFR or FFR.
Generation• Online or offline capacity that can be converted to energy within 10 minutes
• Dispatched by SCED
Load Resources (UFR not required)• Up to 50% of ECRS capacity can come from Load Resources with or without UFR
• Once deployed, must respond within 10 minutes. Restoration within 3 hours
No protocol changes. • Proposed methodology for Non-Spin Reserve Service quantities in this framework -
quantities computed using 2018 A/S Methodology are reduced by ECRS
quantities.
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Key Takeaways
As the generation mix is changing, ERCOT takes a proactive role
introducing gradual changes to frequency response mechanisms:
• All generators including wind and solar are required to provide primary
frequency response (without capacity reservation);
• RRS requirements is based on expected inertia conditions;
• Load Resource providing RRS are very effective in low inertia
conditions;
• System inertia and RRS sufficiency is monitored in the Day Ahead and
into Real Time;
• Alternative AS Framework proposal is being discussed, includes fast
frequency response service;
• Wind and Solar Generators started seeking qualification for Ancillary
Services;
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