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1
POWER GENERATION OPERATION AND CONTROL
Presentation by
Bruce F. Wollenberg
University of Minnesota
2
Course is based on textbook by Allen J. Wood Bruce F. Wollenberg Gerald B. Shebl
3 3 3
Power System Operations
Operations is a 24 hours/day, 365 days/year job
Photo courtesy Xcel Energy, Minneapolis MN
Large economic effect on
power delivery costs
Economic Dispatch
Unit Commitment
Hydro Scheduling
Fuel Scheduling
4
ECONOMIC DISPATCH
5
Fuel Input$/ton$/bbl$/cuft
Power Output
MW
Students learn to use Lagrange functions and the KKT optimal conditions and how to interpret Lagrange multipliers
Fuel Input$/ton$/bbl$/cuft
Power Output
MW
Fuel Input$/ton$/bbl$/cuft
Power Output
MW
How do we allocate MW output to the generators to minimize the total cost of operating all generators
Scheduling Generation to meet hourly
load the Unit Commitment Problem
0 20 40 60 80 100 120 140 160 1801000
1200
1400
1600
1800
2000
2200
2400
2600
2800
3000
Hours
MW
Hourly load for one week
Sunday Monday Tuesday Wednesday Thursday Friday Saturday
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Students learn how To use Dynamic Programming and Lagrange Relaxation
Hydro units on river networks and
fuel delivery networks
Schedule oil usage so as to not empty storage tank until new supplies are available
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Schedule hydro to avoid overflow of reservoirs
Students learn to use Linear Programming
Transmission System
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9 9 9
Power System Security
Lightning, rain, wind, and vehicles can cause a transmission line to fail
Failure can result in other lines overloading and voltages to sag
Operations must take transmission
system into account
All lines and transformer flows within limit
All bus voltage magnitudes within limit
No first contingency outages will result in any flow or
voltage limit violations (the (N-1) rule)
Any violations must be corrected
Economic dispatch must account for transmission losses
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Students use Newton and Decoupled Power Flow, Linear Power Flow and PTDF and LODF factors
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What Happens If We Ignore
System Security?
Times Square, New York City, August 14, 2003
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Control of Generation, frequency,
and power interchange
L O A
D
G O
V
Pre f
G 3
G 4
G O
V
G O
V
Pre f
Pre f
G O
V
Pre f
C o n tro l A re a R e d C o n tro l A re a B lu e
A G C T ie F lo w
Fr e
qu
en
cy
Ge
ne
ra
t or O
ut p
ut
Ge
ne
ra
to
r O
utp
ut
Automatic Generation Control
(AGC)
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Students learn the importance of well thought out practical control systems
Large Mathematical Applications
State Estimation (least squares and orthogonal decomposition)
Calculate the power flow state from real time measurements
Detect and identify bad measurements
Optimal Power Flow (incremental LP and interior point optimization)
Minimize operating cost
Power flow for entire transmission system as set of constraints
Extend to market calculation of demand and supply
Optimal Power Flow with flow
and line outage constraints
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Power System Operations
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Short Term Demand Forecasting
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Function Forecast Horizon Forecast Intervals
Automatic Generation Control (AGC) Next 15 Minutes 5 Seconds
Economic Dispatch (ED) Next Hour 30 Seconds
Power Flow (PF) Next 2 Days Five Minutes
Optimal Power Flow (OPF)
Contingency Analysis (CA) Next 2 Days Ten Minutes
Situational Awareness (SA) Next Hour 120 Samples Per Second
Voltage Stability (VS) Next Hour 120 Samples Per Second
Unit Commitment (UC) Next 14 Days Hourly
Transaction Evaluation & Management (TEM) Next 14 Days Hourly
Wind Forecasting Next 5 60 minutes 30 seconds
Hydro Forecasting Next 14 days Hourly
Fuel Scheduling Next 1 6 months Weekly
Students are introduced to basic time series modeling such as Box Jenkins, weighted least squares, innovations estimation etc.
Thank you
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