smart operation of systems with deep penetrations of res ... · 00.00 01.00 02.00 03.00 04.00 05.00...

© 2018 Electric Power Research Institute, Inc. All rights reserved.

Miguel Ortega-VazquezSenior Technical Leader, Grid Ops. & Planning

Generation Program Advisory MeetingSeptember 10-13, 2018

Smart Operation of Systems with Deep

Penetrations of RES and Emerging Technologies

2© 2018 Electric Power Research Institute, Inc. All rights reserved.

Agenda

§ A glance at EPRI GO&P§ Introduction§ Market clearing stages and implications§ Flexibility in a market environment§ Integration and participation of storage resources§ Conclusions


Grid (T & D) Operations & Planning Research AreaTransmissionOperations

Bulk System DER &Renewables Integration

Demand Response,Energy Storage, EVs,et. al. technologies

GEN and NUC Programs

Transmission Planning

Distribution Operations& Planning

YearsExp #Staff<5 165-10 1010-20 1220+ 9Total 47Degree/Cert. #StaffDoctorate 29Masters 14Bachelors 4Prof.Eng. 8IEEEFellow 3

System Modeling & Simulation

Expertise


Power System Planning and Operation

MaintainIntegrity

“Green”

Affordable


§ The power industry is undergoing a profound transformation:– Large penetrations of renewable energy sources (RES)– New sources interfaced through power electronics– Active demand and need for greater coordination between T&D– Integration of emerging technologies (e.g. storage, EVs, DER, etc.)– Greater interdependencies with other sectors (e.g. gas)– Electricity as energy carrier for other sectors (e.g. transport)

§ Fundamentally different power system:– Different needs, sources and modelling needs– Adapt existing market structures to accommodate

new entrants and maximize benefits

Power Systems’ Evolution

*Y.-Z.Chen,Z.-G.Huang,H.-F.Zhang,D.Eisenberg,T.P.Seager,andY.-C.Lai,"Extremeeventsinmultilayer,interdependentcomplexnetworksandcontrol,"ScientificReports,Articlevol.5,p.17277,11/27/online2015.

*


% V

aria

ble

Rene

wab

le E

nerg

y(o

f ann

ual e

nerg

y)

System Size (GW)10.10.010.001 100010010

25

50

75

100

80

5

23

Alaskan Village

Ireland Cont. USA

42

Denmark*

Actual Operating System

35

Maui

14CA*

Relatively Easy

Much harder

WWSIS

CA 50%

Lanai Modeled System

ERGIS

REF54

DOE 2050 Goals35% Wind (404 GW)

19% PV (632 GW)

Deep Decarbonization

1400 GW wind

900 GW Solar

78

* Part of a larger synchronous AC power system

20 Germany*

Expectations: Transforming the Grid at a Scale That Matters

Extremely Difficult

B. Kroposky, NREL


Mexico: Expectations and Potential§ Mexico has high RES potential for both, wind and solar§ How to pave the way for its optimal integration?

Sources:SOLARGIS. http://solargis.com/products/maps-and-gis-data/free/download/mexico Mexico Energy Outlook 2016, IEASolar Energy Potential in Mexico´s Northern Borders States, 2012, Wilson CenterWorld Energy Resources: Solar, 2013, WEC Marcelino Madrigal, CRE, 2018

AWS wind data based on actual 2016 meteorology–Hourly output simulated for advanced turbine: 125m hub height, 154m rotor diameter, 4 MW

Annual average solar radiation


MX-REGEN: Regional Loads and Transmission Flows for 2030Reference Case Goodwindresources

andaccesstoU.S.gasmakesNoreste keysuppliertocentralregions

Westernregionsaccountfor22%oftotalload

Annualload(TWh)


Can grids support high levels of RES?

Many grids are operating with 20%–30% or more RESTheir experiences demonstrate that actions taken to integrate wind and solar

are unique to each system, but do follow broad principles.

Country % electricity from RES Balancing

Denmark 60.4% in 2016 Interconnection, flexible generation (including CHP), and good markets

Portugal 27.2% in 2016 Interconnection to Spain, gas, hydro and good market

Spain 42.8% in 2014 Gas, hydro and good market

Ireland 20.9% in 2015 Gas and good market


Why Does Variable Generation Present Operating Challenges?

1. Variability and uncertainty:– Markets à scheduling, planning/operating reserve– A/S à Voltage regulation and frequency control

2. Inverter-based, non-synchronous resources:– Disturbance voltage and frequency performance– System protection coordination

3. May not all be connected at HV level:– Visibility and controllability

3 Key RES Characteristics that Affect Power SystemEconomics and Reliability

RES are often located in

remote areas, thus require

investments in transmission


Distributed PV Impact on System Load Shape

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MW - Lunedì, 30 Agosto 2010



Source: ENEL – Measured Data from Southern Italy

Increased requirement for downward ramping capability in

the morning

More upward ramping capability is required when

sun goes down

Need lower minimum generation levels to avoid over-generation

Lower energy cost & emissions from large tranche of zero fuel

cost and zero emission PV


Example from EPRI InFLEXion tool - Hourly Ramping by Month and Hour in the Southeast US

Large ramps in summer mornings, and winter eveningsAdding 7 GW of solar (8% energy) increases evening winter rampsAdding tracking increases ramps further


50

55

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12:00:00 12:05:00 12:10:00 12:15:00 12:20:00

Pow

er (M

W)

Quantifying the exact reserve needs

Forecast Interval Average Actual

Inter-Interval Variability

Average Interval Uncertainty

Intra-Interval Variability

Risk Tolerance

Operating Reserve Need


Impacts of variability and uncertainty in markets§ Ideally, there should be no deviations from

day-ahead transactions§ Uncertainty and variability unavoidably

materialize, and adjustments are needed in real-time

§ How much are we relaying on real-time transactions?

*Capacity that must be committed by different markets in Western Interconnection

*EPRI, “Dynamic Operating Reserve and Advanced Scheduling Techniques to Support Variability and Uncertainty in Power Systems”, 3002008366, Dec. 2016.

Gate Closure

Results Posted

Binding Periods

Look Ahead Periods

Scheduling Frequency

24 x2 hr24 x 1 hr15 hrs5 min

Day Ahead UC

Daily

4 x 1 hr1 x 1 hr4.5 hrs5 min

Hour Ahead UC

Hourly

11 x 15 min1 x 15 min15 min0 min

Real Time UC

15 Min


Real Time ED

5 Min


Methods to deal with uncertainty/variability

Stochastic UC Interval UC Robust UC Dynamic ReservesUncertainty Model Scenarios Inter-temporal rates Uncertainty range Requirements

Objective min E{cost}Minimize cost to

meet central forecast

min{max{min f}}Minimize operating

cost to meet forecast

Security Depends on thescenarios

Inter-temporal ranges Uncertainty Budget Confidence interval

Scalability Low High Variable (high) High

Y. V. Dvorkin, H. Pandzic, M. A. Ortega-Vazquez, and D. S. Kirschen, "A Hybrid Stochastic/Interval Approach to Transmission-Constrained Unit Commitment",IEEE Transactions on Power Systems, Vol. 30, Issue 2, pp. 621-631, Mar. 2015.


Equivalence between advanced methods and reserves

Multi-period Scheduling withLook Ahead

AdvancedScheduling

Closer Gate Closure

Shorter Scheduling Intervals

Increased Scheduling Frequency

Reserve Needs Advanced methods(implicit recourse)

Reserve Requirement(explicit recourse)

Intra-intervalVariability

Shorter scheduling intervals Regulation reserves

Inter-intervalVariability

Time-coupled multi-perioddispatch w/ longer look-ahead horizons

Flexible ramping reserve

Uncertainty

Stochastic, robust,or interval unit commitment and dispatch

Reserve for unforeseen events(e.g. deviations or even

contingencies)


Industry relevance§ California ISO FlexiRamp

– Reserving flexible capacity for use in real time– Reduce price spikes

§ MISO Ramp Product & Look Ahead Dispatch– Capability to ramp 10-minutes ahead– Further look-ahead for ramping needs assessment

§ Xcel Energy Flex Reserve– Reserve for long-term wind ramps that are not regulation or contingency

§ ERCOT Ancillary Service Redesign– Wide scale reorganization of ancillary service products – Primary frequency response, fast frequency response, inertia service– Regulation requirements based on forecast error characteristics


ERCOT Proposed Ancillary Services

Regulation UpFast-Responding Regulation Up

Current Proposed

Fast Frequency Response 1

Primary Frequency Response

Contingency Reserves 1

Synchronous Inertial Response

Supplemental Reserves 1

Mostly unchanged

59.8 Hz, Limited duration

59.7 Hz, Longer durationFast Frequency Response 2

Contingency Reserves 2

SCED-dispatched

Manually dispatched

Supplemental Reserves 2

SCED-dispatched

Manually dispatched

Ongoing development

Non-Spin

Responsive

Regulation DownFast-Responding Regulation Down

Regulation Up

Regulation Down

Fast-Responding Regulation Up

Fast-Responding Regulation Down

www.ercot.com


Example: Utility study results (small system, 1300 MW peak)

Benefits system dependent based on quantity of variability and uncertainty, scheduling process, decisions that can be made, and existing reserve method.

Base case Static Rqmt90% conf.

By VER90% conf. EPRI 90% conf.

Operating cost, $ 531.76 M 542.22 M 541.47 M 539.29 M

Total violations (12×MWh) 2,148,894 197,027 153,653 103,333

Base case (RT Commitments)

EPRI 50%(RT Commitments)

Operating cost, $ 596.53 M 593.79 M

Total violations (12×MWh) 114,264 31,239

Utility Study found $20-$24M (3-4%) in savings using dynamic reserve method and cycling of mid-merit resources

Simultaneous Reliability Improvement and Cost Reduction

Significant Reliability Improvement at Modest Cost Increase


Taxonomy of resource contributionsEPRI whitepaper (2015):Contributions of Supply

& Demand Resources to Required

System Reliability Services

(3002006400)


Options to increase flexibility (from NREL)


FERC Order 841 – Energy Storage Resources (ESR)§ ESR: “A resource capable of receiving electric energy from the grid and storing it

for later injection of electric energy back to the grid”

§ Summary:– Include participation model for ESRs in energy, A/S, and capacity markets if technically able to

do so§ Also includes ability to provide services that are not procured through organized market

(frequency response, voltage support, black start)– Eligibility of the ESR to set prices as buyer and seller when marginal– ISOs must account for technical parameters of the ESR through bidding or otherwise– ISOs must allow a minimum size requirement that is at most 100 kW– Energy stored from purchases in the wholesale market must be sold at wholesale prices


Order 841: ESR Operating CharacteristicsPhysical or Operational Characteristic Definition

State of Charge (% or MWh) State of Charge represents the amount of energy stored in proportion to the limit on the amount of energy that can be stored, typically expressed as a percentage. It represents the forecasted starting State of Charge for the market interval being offered into.

Maximum State of Charge (% or MWh) Maximum State of Charge represents a State of Charge value that should not be exceed (i.e., gone above) when a resource using the participation model for electric storage resources is receiving electric energy from the grid.

Minimum State of Charge (% or MWh) Minimum State of Charge represents a State of Charge value that should not be exceeded (i.e., gone below) when a resource using the participation model for electric storage resources is injecting electric energy to the grid.

Maximum Charge Limit (MW) Maximum Charge Limit represents the maximum MW quantity of electric energy that a resource using the participation model for electric storage resources can receive from the grid.

Maximum Discharge Limit (Pmax) (MW) Maximum Discharge Limit represents the maximum MW quantity that a resource using the participation model for electric storageresources can inject to the grid.

Minimum Charge Time (minutes/hours) Minimum Charge Time represents the shortest duration that a resource using the participation model for electric storage resources is able to be dispatched by the RTO/ISO to receive electric energy from the grid.

Maximum Charge Time (minutes/hours) Maximum Charge Time represents the maximum duration that a resource using the participation model for electric storage resourcesis able to be dispatched by the RTO/ISO to receive electric energy from the grid.

Minimum Run Time (minutes/hours) Minimum Run Time represents the minimum amount of time that a resource using the participation model for electric storage resources is able to inject electric energy to the grid (already provided by other generators).

Maximum Run Time (minutes/hours) Maximum Run Time represents the maximum amount of time that a resource using the participation model for electric storage resources is able to inject electric energy to the grid.

Minimum Discharge Limit (MinGen) (MW) The minimum MW output level that a resource using the participation model for electric storatge resources can inject onto the grid.

Minimum Charge Limit (MW) The minimum MW level that a resource using the participation model for electric storage resources can receive from the grid.

Discharge Ramp Rate (MW/min) The speed at which a resource using the participation model for electric storage resources can move from zero output to its Maximum Discharge Limit

Charge Ramp Rate (MW/min) The speed at which a resource using the participation model for electric storage resources can move from zero output to its Maximum Charge Limit.

“the following chart summarizes the physical and operational characteristics of electric storage resources for which each RTO’s/ISO’s participation model for electric storage resources must account”-FERC


Order 841: Capacity Market Eligibility§ ESR must be allowed to participate in capacity markets if able to do so§ Capacity contribution based on ratio of power to energy duration

Example: Energy Storage Capacity ValueStatus quo*: Ruling:

Power Capacity: 10 MWEnergy Storage: 40 MWhCapacity Value: 10 MW




*In some markets

Key Question: What is the most appropriate way to measure capacity contribution from energy storage?


State of Art – ESR Participation§ PSH exists in great quantities in ISO-NE, NYISO, MISO, PJM, and CAISO and

participates in majority of ISO services:– Offer in as separate pump or gen. units that can get selected by ISO energy and ancillary

markets– PJM – Hydro optimizer, optimize mode of operation to minimize cost and leave PSH with

ending reservoir level and SoC limits§ Other limited ESR (e.g. less than a few hours of endurance) primarily participate

in ISO regulation market– Some software limitations for provision of energy and other A/S (SoC management?)– Regulation service typically most lucrative for ESR (bi-directional, mileage payment, etc.)– Typically only requires 15 minutes of sustained energy

§ CAISO Non Generator Resource - Submits offer curve from max consumption to max generation and can be selected anywhere between


Conclusions§ Variability and uncertainty have a profound effect on market outcomes§ The reserves should be estimated in a smart manner

– Assessment of the actual requirements:§ Uncertainty§ Inter-interval variability§ Intra-interval variability

§ Smart reserves can:– Reduce operating costs– Increase system reliability

§ Storage is a versatile result that can participate in energy, A/S and capacity markets– The value of storage is system dependent, regulation services are favored– Efforts to normalize the participation of across RTOs and ISOs


Together…Shaping the Future of Electricity


Support Material


Trends Impacting Operation and Planning ProcessesChanging Generation Mix Consumer Choice/Control and

Electrification

Active Distribution SystemsHigh-Impact, Low-Frequency


Market Clearing Processes

24 x2 hr24 x 1 hr15 hrs5 min

Day Ahead UC

Daily

4 x 1 hr1 x 1 hr4.5 hrs5 min

Hour Ahead UC

Hourly


Real Time UC

15 Min


Real Time ED

5 Min

Gate Closure

Results Posted

Binding Periods

Look Ahead Periods

Scheduling Frequency


Where are the flexibility needs resolved?§ Ideally, there should be no deviations from day-ahead transactions§ Uncertainty and variability unavoidably materialize, and adjustments are needed

in real time§ How much are we relaying on real-time transactions?

*Capacity that must be committed by different markets in Western Interconnection

*EPRI, “Dynamic Operating Reserve and Advanced Scheduling Techniques to Support Variability and Uncertainty in Power Systems”, 3002008366, Dec. 2016.

Horizon length

Cyc

les’

gran

ular

ity


Three Central Needs for Operating Reserve1.Hold capacity now to meet the variability that occurs within the current

scheduled time interval.

2.Hold capacity now to prepare for anticipated variability that occurs after the current time interval.

3.Hold capacity now to prepare for uncertain outcomes that are different from those used in scheduled time intervals.

Intra-interval variability

Inter-interval variability

Uncertainty


Order 841: Electricity Product/Services Participation§ Energy, all A/S, capacity markets when technically capable:

– ISO determine what/when it is capable of providing– Also includes ability to provide services that are not procured through organized market

(frequency response, voltage support, black start)§ Ancillary Service Provision

– No changes to NERC Glossary or Standards: – No requirement for the ISOs to change rules to allow for ESR to provide ancillary services

without energy schedule, but encourage them to allow it when appropriate§ Capacity markets

– Allow De-rate to participate (next slide)– No changes to must offer rules


Order 841: Price setting and Settlement§ Must pay/be paid price as a wholesale buyer and seller and set price as

wholesale buyer and seller and when available as a dispatchable resource and marginal resource– If block loaded or self-scheduled, cannot set price

§ Include make whole payments (e.g. cost recovery guarantee) when price is higher than bid price when charging or lower than offer price when discharging

§ Prices for buying and selling at nodal level, not zonal§ Transmission charges to load can be applied to ESR when charging§ Require direct metering for better accounting of wholesale


State of Art – Pricing

§ All ISOs – storage that participates as generator can set price§ ISO-NE – Allows PSH in pumping mode to set price as part of fast-start pricing

logic (relaxes block loading)§ PJM – PSH model separate from pricing model – cannot set price§ CAISO – Continuous ESR (NGR) can set price in either mode based on

continuous offer curve§ ISO-NE – Allows make whole payment (NCPC) for PSH when prices are above

consumption bids


Demand Response as Flexible Resource§ Types of Loads:

– What will be available and when?– How long will it be available for?– How is it controlled?– Will be examined in this project and quantified for case studies– Can contribute to system operators assessment of DR as a

resource for providing operational flexibility§ DR operations:

– Ramp limits– Call rate limits– Energy limits– Duration limits– Time of day/week/year availability– Efficiency of pre-loading & make up energy

System Operators will need to be able to characterize if and how DR can provide operational flexibility


Together…Shaping the Future of Electricity

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