Hydro Power from a Control Engineering Perspective

Hydro Power from a
Control Engineering Perspective
Bernt.Lie@hit.no
Telemark University College
2 nd International Seminar on Renewable Energy, UiA, Grimstad, May 31, 2011

Overview
• The need for
renewable energy
• Hydro power systems
• Modeling HPS
• Simulation tools
• Controlling HPS
• Hydro power &
renewable energy
2

The need for renewable energy
Human needs:
• Fresh air (1 min)
• Fresh water (1-2 d)
• Food (2 weeks)
• Humane conditions
(culture, democracy)
• Health
• Standard of living
Renewable resources:
• Municipal solid waste
• Hydro – small/large scale
• Wind – onshore/offshore
• Biofuels – energy crops,
forestry wastes,
agricultural wastes
• Wave – shore/offshore
• Tidal – stream/barrage
• Solar – PV/thermal
3

Hydro power around the globe
Location Capacity Production P/C Comment
Norway 30 GW 135 TWh 0.5
Switzerland 35 TWh 47% RofR
Sweden
16 GW
Finland 3 GW 10-17 TWh 0.4-0.65
Denmark 4 MW Tangenværket
EU 120 GW 365 TWh 0.35
Three Gorges, China 22.5 GW 80 TWh 0.5
Itaipú, Paraguay 14 GW 93 TWh 0.75
USA 95 GW ?
Minnesota 0.15 GW ? RofR
Grand Coulee Dam 6.8 GW 20 TWh No. 5

Hydro power systems – history I
• Undershot wheel:
China/Egypt several
thousand years ago
• Rivers and shallow canals
• Overshot wheel: improved
design
• Artificial falls up to 3 m
• Best designs: 85% eff.
www.top-alternative-energy-sources.com/water-wheel-design.html
5

Hydro power systems – history II
Flour mill
Saw mill
farm, Norway
www.top-alternative-energy-sources.com/
water-wheel-design.html
6

Hydro power systems – main principle
• Water level
difference
• Water flow
• ‘’Turbine’’
• Generator
• ‘’Grid’’ with
load
www.green-trust.org/hydro.htm

Hydro power systems – high head plant
intake tunnel
surge shaft
reservoir
grid
penstock
aggregate
downstream

Modeling HPS: turbine model I
Pelton turbine
nozzle
needle
jet
bucket
overspeed deflector
9

Modeling HPS: turbine model II
Francis turbine
Kaplan turbine
guide vanes
water flow
runner
guide vanes
runner
blade pitch
propeller blades
water flow
10

Modeling HPS: turbine model III
D. Winkler
Admission: scaled volumetric flowrate
11

Modeling HPS: penstock model I
surge shaft
aggregate
penstock
12

Modeling HPS: penstock model II
Compressible water
Elastic penstock wall
13

Modeling HPS: penstock model III
40
Incompressible vs. compressible transfer function
j♒()j (dB)
20
0
-20
-40
10 -1 10 0 10 1 10 2 10 3
100
50
6 ♒()
0
-50
-100
10 -1 10 0 10 1 10 2 10 3
(rad/ s)

Modeling HPS: waterway model
15

Modeling HPS: turbine power
16

Modeling HPS: aggregate
17

Modeling HPS: synchronous generator I
18

Modeling HPS: synchronous generator II
Two pole salient rotor/3 phase
Example
19

Modeling HPS: synchronous generator III
Park transformation:
Constant parameters in (0,d,q):
20

i
Modeling HPS:synchronous generator IV
Electric torque:
Short circuit, constant ω a :
1.5 x 105
Three-phase current i a
, δ = 0°
1
0.5
i a
, A
0
-0.5
-1
-1.5
0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1
t, sec
1
Three-phase flux linkage lam a
, δ = 0°
0
-1
lam a
, Wb.turn
-2
-3
-4
-5
-6
0 0.5 1 1.5 2 2.5
t, sec
21

Modeling HPS: interface + grid
• Transformer:
• Transmission line:
Open terminal case:
22

Modeling HPS: customer
• Resistive or complex
load
• Grid + load give phase
lead/lag in system:
• Load changes:
– change of phase lag
– variation in Active
Power, P A
• Necessary to keep
track of:
– Active vs. Reactive
power
– Voltage amplitude
23

Simulating HPS I
LVTrans & LabVIEW

Simulating HPS II
HydroPlant & Dymola (Modelica)

Controlling HPS I
• Turbine opening u t
controls ω a /W m
• Field voltage v f
controls line voltage/
active-reactive power
26

Controlling HPS II
What is special about control
of electrical power?
• Difficult to store electrical
energy
– Balance is attempted at all
time
• Common grid frequency
• Common (consumer) grid
voltage
27

Controlling HPS III
Multi generator grid:
• all generators lock in to
the same electric
frequency
http://en.wikipedia.org/wiki/Crankshaft
28

Trends: Renewable energy & storage
Renewable resources:
• Municipal solid waste
• Hydro – small/large scale
• Wind – onshore/offshore
• Biofuels – energy crops,
forestry wastes,
agricultural wastes
• Wave – shore/offshore
• Tidal – stream/barrage
• Solar – PV/thermal
Storage possibilities:
• Pump storage hydro
plants
• Plug-in cars/batteries
• Electrolysis of water into
hydrogen + fuel cells
• High temperature water
(T>100C for electricity,
district heating, etc.)
• High temperature vapor
29

Trends: hydro power + wind power etc
Renewable power
varies:
wind
Demand varies:
tidal
Power can be predicted:
wind
G. Boyle (ed): Renewable Electricity and the Grid. The challenge of variability., 2007, Earthscan, London
30

Trends: hydro power + wind power etc
• Increased power
production from
renewable resources
(wind, etc.) in Europe
• Hydro power admits rapid
production variation
• Stored hydro power
(reservoirs) suitable as
balance power
• Run-of-river hydro power
less suitable
• Increased transmission
capacity necessary
• Many small sources
increased safety
requirements
• Growing need for rapid
and good control of hydro
power
31

Conclusions
• Hydro power production requires knowledge in many
fields
• Stored hydro power is suitable as balance power for other
renewable energy resources
• The new interconnected grid of renewable energy sources
poses challenges for optimal operation
• Modeling and simulation key technologies for optimal
energy usage

Bibliography
33