A Smarter Dispatch for Smart Grid - University of Washington...2011/11/17 · −Robust Commitment...
Transcript of A Smarter Dispatch for Smart Grid - University of Washington...2011/11/17 · −Robust Commitment...
A Smarter Dispatch for Smart Grid
Dr. Xing Wang
Nov 17, 2011 @ UW
Outline
• Smart Grid’s Impacts on Grid and Market Operations
• Smart Dispatch
• PJM Implementation Example
• Dispatch Demand Response
• Future Development
Smart Grid’s Impacts On Grid And Market Operations
Smart Grid’s Impacts on Grid and Market Operations
Smart Dispatch
Smart Dispatch Market Drivers
• Society’s growing dependency on electricity − Looming risks of major system disturbances − Focus on reliable demand-supply balance & grid security
• Global energy & environmental movement
− Increasing presence of DER - Distributed Energy Resources (e.g. wind, DR, etc) − Operational challenges: DER performance uncertainties
• Experiences from deregulated system operations
− Established foundation for integrating demand-supply balance with grid security constraints (e.g. LMP). − Identified emerging deficiencies in Dispatch Instructions
• Unrelenting complexity in business & technical decision process
Smart devices/resources with distributed intelligence
Coordinated decision making
Resource Scheduling and Dispatch Evolution of Capabilities
• Classical Dispatch
− Unit Commitment Scheduling, Economic Dispatch, AGC − Grid security, scheduling, dispatch are Independent tasks
• Market-Based Dispatch
− UC/ED with explicit transmission security constraints − Formal Day-Ahead and Real-time tasks − Pricing - Dual of the MW signal − Transparency & consistency − Large-scale system dispatch
• Smart Dispatch
− Dispatch with explicit forward vision − Dispatch with intelligence (e.g. parameter adaptation) − Improve system robustness against uncertainties (e.g. DER, Wind, DR) − Mitigate root-causes for dispatch deficiencies − Process re-engineering for business/economic analysis
Challenges in Demand Forecast and Reserve Estimation
• Increase amount of uncertainties
• Sources (Demand Response, distributed energy resources, wind)
• Demand forecast
• Need better predictability
Dimensions of Smart Dispatch Applications
Time
Scen
ari
os
AFA
SKED 3
SK
ED
-DA
SK
ED
1
SK
ED
2
PD
(Ro
bu
stn
es
s)
(Forensic
Analysis) (Vision)
Comprehensive Operating
Plan (COP)
SKED 1
t=30,60,90,120,180...720..
SKED 2
t=15,30,45,60...
SKED 3
t=5,10,15...5 min
Quarter
Hourly
Hourly
Outages
Demand Forecast
Adaptive Model
Management
5 min to
Hourly
On Demand
Asynchronous
Explicit Real-time
Dispatch
Implicit/Indirect DispatchAfter-the-Fact
Forensic Analysis
Perfect Dispatch
5 minOn Demand
5 min On
Demand
Physical System
OperationArchived System
Operation History
5 min
5 min On Demand
On
Demand
Smart Dispatch Overview
Adaptive Generator Model
• Operational history of resource used to predict response to certain dispatch instructions
• Predicted response used in determining dispatch instruction to be issued to resource
• Probabilistic response model replaces need to correct bad offer data or explicitly model mill points, dead bands, forbidden zones etc.
Adaptive Constraint Model
• Provide analysis to evaluate near-term line loading trends (and PV characteristics) to adapt constraint control strategy based on current conditions
• Group, rank and prioritize active transmission constraints
• Incorporate historical data to assist in anticipating and strategizing constraint control actions
• Reduce number of “hard” limits that are introduced into the optimization phase
SKED Optimization Engine
• SKED is a Mixed Integer Programming (MIP) / Linear Programming (LP) based optimization application which includes both unit commitment and unit dispatch functions. SKED can be easily configured to perform scheduling processes with different heart beats and different look-ahead time.
− Robust Reliability Unit Commitment (SKED1)
• Look ahead 6-12 hours with hourly intervals − Short-Term Look-Ahead Scheduling (SKED2)
• Look ahead 2-4 hours with 15-minute intervals − Real-time Dispatch and Pricing (SKED3)
• Look ahead 1 hour with 5-minute intervals
• Physical unit commit against the forecasted system conditions with consideration of uncertainties.
− Robust Commitment for slow start units
• Load and Generation Variations
• Interchange Variation
• Topology Uncertainty − Identification of Pre-ramping needs
• A multi-period security constrained unit commitment.
− Stochastic Approach − Robust Approach − Scenario-based Approach
Robust Reliability Unit Commitment
• Commitment Decision:
− Robust commitment of fast-start units only
• Scheduling Recommendation:
− Interchange schedules − Selection of regulation units − Demand response activation − Outage and ramping preposition
• Condition Prediction:
− Emergency conditions: capacity excess and shortage − Price prediction − Transmission congestion prediction
Short-Term Look-Ahead Scheduling
• Clears the real-time energy and ancillary service markets.
• Solves a multi-period security constrained economic dispatch problem:
− Balance the load while maintaining the system security. − Schedule the energy and ancillary service outputs for dispatchable
resources. − Compute the market clearing prices (ex ante or ex post) − Consider more accurate unit characteristics (start-up and shut down
profile, forbidden zone etc…)
Real-time Dispatch and Pricing
Comprehensive Operating Plan (COP)
• COP is an application to coordinate scheduling data to and from a certain class of power system applications and present a comprehensive, synchronized and more harmonized view of scheduling data to applications, to system operators or other stakeholders for the purpose of power system operations.
COP3
SCED3
Synch
COPt
COP2
SCED2
Synch
COP1
SCED1
Synch
AGM
Other data
ACM
AGM
Other data
ACM
AGM
Other data
ACM
Overrides MOI
SKED3
SKED2
SKED1
t0 t1 t2 t3 tn t1(sc2)
SKED-2 (M)
Low
SE time
stamp
Pgmin(tn)
....
SE
Pgmax(tn)
High
Medium
t2(sc2) t3(sc2)
Coordination Between Schedulers for Reach-ability
Envelope of reachability
After-the-Fact Analysis
• After-the-Fact Analysis (AFA)
Systematic analysis of past events and practices
Quantitative assessments of how do specific events and practices affect system performance
Use-case comparative approach
• Perfect Dispatch
A class of use cases of AFA that focus on “Day-After” analysis of the performance of actual system dispatch results, including the impacts of specific events.
Smart Dispatch Visualization
PJM GCA Implementation Example
From Andy Ott’s presentation at Panel “Smart Dispatch For Grid and Market Operations”, IEEE PES GM 2011.
»PJM©2011
»Day Ahead and Real Time Market Cycle
1. System Outage Analysis and Coordination
2. Day Ahead Market Clearing
3. Reliability Assessment Commitment
4. Real Time Market CT
Commitment
5. Real Time Market Economic
Dispatch
6. Perfect Dispatch Analysis
»PJM©2011 »23
GCA Architecture
»www.pjm.com
»PJM©2011 »24 »www.pjm.com
Observations
• Adaptive Models enhance performance of dispatch engines
• Real-time Optimization performance must improve to support automation
• Trend visualization well received by dispatchers
• Market response will be enhanced by reduction in dispatch base point volatility and producing dispatch signal trajectories for all resources
»PJM©2011 »25
• Unit A – 9/16/09 – Unloading of the unit with basepoint reversal
»www.pjm.com
Turn Around Effects
»PJM©2011 »26 »www.pjm.com
Mill Effects
• Unit B – 9/8/09 – Volatile basepoint moves through non-operating band
A Multi-tier Framework For Demand Response Dispatch
Price Responsive Demand
• Enabled by “Smart Grid”/AMI technology
• Residential and small commercial consumers
• Not directly dispatchable by RTOs/ISOs
• Aggregated to Transmission bus level
• Price Responsive/retail dynamic pricing
• Includes Distributed Energy Resources (DERs)
• Have significant impact to market and grid operation
Multi-Tier Optimization Framework
• Each tier has its own objectives and constraints
• Information flow between tiers is bi-directional. Coordination is required between tiers but it should be asynchronous.
• Parent tier provides a “bulk” guideline/incentive over a number of look-ahead intervals for its child tiers
• Child tier provides aggregated feedback (forecast MW values) over a number of look-ahead intervals to its parent tier
Multi-Tier Optimization Framework
• RTO/ISO Tier − Support regional transmission level objectives − Transmission network model and bulk generation/load model − Distributed resources and demand responses are modeled as aggregation
(either MW forecast or MW-Price curves) − Price/incentive signals are at aggregated/bus pnodes level − Annual/monthly/weekly/day-ahead/intra-day/real-time coordinated
rolling scheduling/dispatch processes
• Market participant/utility tier − Portfolio optimization − Process the LMP received from RTO − Aggregation function − DMS function provider
Multi-Tier Optimization Framework
• Aggregators/Commercial building Owners
− Detailed neighborhood/building modeling − Distributed resource/storage devices scheduling based on
upstream incentive signals − Local network optimization/feeder reconfiguration for loss
reduction, etc. − Provide aggregated MW feedback signals to upstream tier − Request distribution network information from utility DMS
• Household scheduling/distributed resource optimal control
− Monthly electricity bill reduction − EV/PHEV charging scheduling − Smart appliance optimal control
Future Development
• Advanced algorithms to deal with uncertainties
− Stochastic unit commitment − Robust unit commitment
• Computational performance enhancement
− Problem decomposition and parallel solving − Utilizing multi-core technology
• Distributed optimization
• Cloud computation
Thank You!