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Hydro Power 102Hydro Power 102
Hydroelectric ModelsHydroelectric Modelsin thein the
NorthwestNorthwest
Three Regional Models
Hydro Simulator Program (HYDROSIM)– Bonneville Power Administration
Hydro System Seasonal Regulation (HYSSR)– Corps of Engineers
PNCA Seasonal Regulation (HYDREG)– Northwest Power Pool
Common Elements
Simulate the hydroelectric operation over 14 periods per year (split April and August)
Share hydroelectric project data Share historical stream flow/irrigation data Share flood control data
HYDROSIM - BPA
Columbia River Treaty (Coordination with the Canadian Operation)
White Book (NW Loads and Resources)
EIS (Environmental Impact Statement)
Biological Opinion (Endangered Species)
Long-term planning
HYSSR - Corps
Columbia River Treaty (Coordination with the Canadian Operation)
Flood Control Development
EIS (Environmental Impact Statement)
Biological Opinion (Endangered Species)
Evaluation of System Changes (new storage, revised irrigation withdrawals, etc.)
HYDREG - PNCA
Power Pool Operating Program
Critical Period Evaluation
FELCC
(Firm Energy Load Carrying Capability)
Headwater Benefits
Each Party’s Rights and Obligations
Modeling the Modeling the Hydroelectric SystemHydroelectric System
Tapping the Power of the RiverA Few Definitions
Potential Energy = stored energy proportional to the height above ground
Kinetic Energy = energy of motion proportional to the velocity
Tapping the Power of the River
A ball resting at the top of an incline has no motion and thus no kinetic energy.
With a little push, the ball rolls down the incline, picking up speed as it rolls.
At the bottom, the ball has its highest speed but can fall no further.
This is an example of converting potential energy to kinetic energy.
Tapping the Power of the River
Water in the forebay is passed through a turbine.
As the water falls, it forces the turbine blades to turn.
As the turbine rotates, it converts the mechanical energy of rotation into electricity.
Thus, we can capture some of the water’s potential energy.
Tapping the Power of the River
Power = Flow x Head x ConstantPower is measured in megawatts (million watts)
Flow is measured in cubic feet per second
Head is measured in feet
Constant is a function of the turbine’s efficiency
Example at Grand Coulee DamFlow is 100,000 cubic feet per second
Head is 328 feet
Constant is .075
Power = 100,000 x 328 x .075 = 2,460 megawatts
A Simple Example One River, One DamNo Storage, No Constraints
Energy as a function of Volume Runoff
0
2000
4000
6000
8000
10000
0 10 20 30 40 50 60 70 80 90 100
Volume Runoff (Maf)
En
erg
y (a
MW
)
A Simple Example One River, One DamNo Storage, No Constraints
Distribution of Volume Runoff
0
20
40
60
80
100
120
0 20 40 60 80 100 120
Volume Runoff (Maf)
Pro
bab
ilit
y
Developing a Planfor Our Simple System
What is the range of generation?
What is the average generation?
How much generation can we guarantee (year after year)?
What can we do to increase the amount of guaranteed generation?
Statistics for Our System
Minimum Runoff Volume 20 Maf
Minimum Generation 2,000 aMW
Maximum Runoff Volume 100 Maf
Maximum Generation 10,000 aMW
Average Runoff Volume 60 Maf
Average Generation 6,000 aMW
Guaranteed Energy 2,000 aMW
Improving Our Simple Systemby adding 20 Maf of Storage
What is the range of generation?
What is the average generation?
How much generation can we guarantee (year after year)?
Our Modified System
When storage is full:
minimum generation 4,000 aMW
average generation 8,000
maximum generation 12,000
When storage is half full:
minimum generation 3,000 aMW
average generation 7,000
maximum generation 11,000
Guaranteed generation depends on how much water is in the reservoir
Guaranteed Generation:
Condition 1 (full) 4,000 aMW
Condition 2 (half full) 3,000 aMW
Condition 3 (empty) 2,000 aMW
Improving Our Systemby Taking Some Chances
Distribution of Volume Runoff
0
20
40
60
80
100
120
0 20 40 60 80 100 120
Volume Runoff (Maf)
Pro
bab
ilit
y
95 %
Guaranteed Generation can be Increased if Contingency Actions are in Place
95 % of the time the runoff volume is at least 30 Maf
Contract with a customer to drop load in case of low water in return for better price
This action effectively increases the guaranteed generation by 1,000 aMW
Monthly Distributionof
Demand and Generation
Generation from Flow
2000
4000
6000
8000
10000
12000
14000Flow
Shape of Demand
2000
4000
6000
8000
10000
12000
14000
Sep Oct Nov Dec Jan Feb Mar Apr May Jun Jul Aug
Demand
Critical Period Planning
Required by the Pacific NW Coordination Agreement
Portion of the historical water record that produces the least amount of energy (namely the driest conditions)
Reservoirs are drafted from full to empty Stored water is used to maximize the
generation while matching the monthly shape of demand
Results in the Firm Energy Load Carrying Capability (FELCC)
Guaranteed GenerationNo Storage
2000
4000
6000
8000
10000
12000
14000Flow
Demand
SurplusSurplus
Guaranteed GenerationWith Storage
2000
4000
6000
8000
10000
12000
14000New Flow
Firm Gen
Shape of Electricity PricesCompared to the Shape of NW Demand
15
25
35
45$/
MW
-hou
r
Demand
Prices
Developing Operating Guidelinesfor the
Hydroelectric System
Rule Curves
Rule curves are simply elevations at each reservoir that help guide the operation (i.e. drafting or filling)
Rule curves specify the highest and the lowest elevation that a reservoir should be operated to in order to stay within the planning objective
Intermediate rule curves help determine which projects release water first when energy is needed
Rule Curves
Flood Control– defines the drawdown required to assure
adequate space to store the anticipated runoff without causing downstream flooding (Maximum Elevation).
Critical Rule Curve– defines how deep a reservoir can be
drafted in order to meet the firm energy requirements during the poorest water conditions on record (Minimum Elevation).
Rule Curves
Assured Refill Curve– represents the elevation from which the
reservoir could refill given the water conditions that occurred in 1931.
Variable Refill Curve (Energy Content Curve)– represents the elevation from which the
reservoir could refill given current water conditions.
Rule Curves
Actual Energy Regulation (AER)– defines how deep a reservoir can be
drafted in order to meet the firm energy requirements during the current water conditions.
Proportional Draft Point (PDP)– same as the AER above.
Rule Curves
0
900
1800
2700Co
nten
t (ks
fd)
Flood
Refill
AER
CriticalMinimum Content
Maximum Content
Value of Water in Storage
Very Cheap
Moderate
Expensive
Very Expensive
Em ergency Only
Flood Control Curve
Assured Refill Curve
Actual Energy Regulation
Critical Rule Curve
Em pty
How the Model Works
General Methodology
Starting with the most upstream reservoir, draft (or fill) each dam to its Variable Refill Curve
Check for constraint violations Calculate total generation If generation equals desired amount, we’re
done If generation is less than desired,
proportionally draft If generation is greater than desired,
proportionally fill
Calculating the Desired Amount of Hydro Energy
Start with NW firm demand Subtract (or add) firm contracts (i.e. exports
and imports) Subtract the expected thermal operation Subtract generation from miscellaneous
resources and small hydro Yields a residual demand that must be served
by the hydro system
Non-Power Constraints
Physical limits (i.e. top & bottom of dam) Maximum flow due to channel restriction Maximum elevation for flood control Maximum flow due to rate of draft limit Operational minimum & maximum flow rate Operational minimum elevation Water budget flow target Spill level
GENESYSGENESYSNorthwestNorthwest
A PC based program, incorporating the HYDROSIM algorithms
Performs stochastic (probabilistic) studies Dynamically simulates the interaction of
hydro, thermal and out-of-region resources Identifies potential reliability shortfalls, both
long-term (energy deficiencies) and short-term (peaking or capacity problems)
Assesses changes in the physical operation of the hydro system
