Small Wind Turbines and Wind Pumps - Välkommen till KTH · PDF fileThomas Ackermann...
Transcript of Small Wind Turbines and Wind Pumps - Välkommen till KTH · PDF fileThomas Ackermann...
Thomas Ackermann November 2015
Small Wind Turbines & Wind Pumps & Wind Diesel Systems
Thomas Ackermann, Ph.D.
Expert User of DIgSILENT PowerFactory for Power Systems Studies
Contents
Part 2: Wind Pump Systems
2
Part 1: Small Wind Turbines
Part 3: Wind-Diesel Systems
Thomas Ackermann November 2015
Contents
Part 2: Wind Pump Systems
3
Part 3: Wind-Diesel Systems
Part 1: Small Wind Turbines
Typical Markets for Small Wind Turbines (< 50 kW)
Remote Homes
Telecommunications
Village/ Rural Electrification
Water Pumping
Oil Well Pumping
Refrigeration
Desalination
4
Thomas Ackermann November 2015
Rural Electrification
World Bank projects in:
Brazil;
Russia;
Indonesia;
China;
Mexico ...
5
6
Thomas Ackermann November 2015
7
Features of Small Turbines for Power Generation
Larger tower, compared to turbine size;
Mainly variable speed, direct driven systems (no gearbox) for 2 to 10 kW; direct driven systems are also under development for turbines between 10 to 50 kW (Reason: High rotor speed well suitable for direct driven systems);
8
Thomas Ackermann November 2015
9
Generators
Low Cost Alternatives:
Alternators are very popular (Advantage: cheaper, long life time);
Induction motor (washing machine);
Advanced Alternatives:
AC generators (very seldom DC);
Permanent magnet generators;
10
Thomas Ackermann November 2015
Power regulation
Yaw (~ 10 %);
Stall (~ 8 %);
No Control (~ 14 %);
Pitch (~ 35 %);
Tilt (~ 33 %)
11
Yaw/ Horizontal Furling
12
Thomas Ackermann November 2015
13
14
Thomas Ackermann November 2015
15
Tilt/ Vertical Furling
16
Thomas Ackermann November 2015
Pitch Control
17
18
Thomas Ackermann November 2015
19
Blades
Often very bad aerodynamic design for small blades, e.g.
455 kW/ m2 for Bonus 600 kW
260 kW/ m2 for Bergey 10 kW;
Good research in this area is done by the University of New South Wales, Newcastle, Australia
20
Thomas Ackermann November 2015
Maintenance
Low maintenance costs is the key, however, it is often very difficult ton achieve;
Also, very difficult and risky to climb up a large tower to repair/ maintain a small wind turbine;
21
22
Thomas Ackermann November 2015
Grid Connection I
23
Induction Generator
Easy to synchronize with the network;
Cheap and easy;
BUT: Requires reactive power, hence a reactive power source needed!
Voltage different to regulate;
24
Thomas Ackermann November 2015
Synchronous Generator
Reactive power generation possible;
Easy to control;
BUT: Must be synchronized in frequency, phase and current;
25
DC Generator
Direct connection to battery possible (Battery charger);
No synchronisation required;
Low efficiency;
Repair of DC generator can get very expensive;
26
Thomas Ackermann November 2015
Battery & Inverter
Power output can be regulated;
Easy to synchronise;
Can supply reactive power;
Expensive;
Control might be difficult;
Lifetime of Battery limited.
27
Contents
Part 2: Wind Pump Systems
28
Part 3: Wind-Diesel Systems
Part 1: Small Wind Turbines
Thomas Ackermann November 2015
Water - Pumping
Cut subsidies to save water and to find economic ways to pump water (India has estimated 12 million electric pump sets, but only several thousand wind/solar pump sets)
Without subsidies (Yemen): 50-60 cents US/ kWh for electricity;
29
WIND PUMP SYSTEMS
30
Thomas Ackermann November 2015
Electrical Water Pumping
31
Wind Pump Systems
32Pump
mechanical coupling
gearbox
belt drive
Thomas Ackermann November 2015
Typical Situations
Small pumped volumes high pumped heads (> 20 m), often drinking water;
Medium pumped volumes medium pumped heads (5 - 20 m), often livestock;
Large pumped volumes small pumped heads (< 5 m), irrigation, drainage.
33
Operating Principle Pump
34
Pmech = 2 Pi M n
Ppump = pw g Q H
Thomas Ackermann November 2015
Pumps
A: Piston pump
B: Diaphragm pump
C: Eccentric screw pump
D: Single-stage centrifugal pump
E: Multistage centrifugal pump
F: Screw pump
G: Chain pump
H: Mammoth pump
35
36
Thomas Ackermann November 2015
37
A: piston pump
B: diaphragm pump,
C: eccentric screw pump,
D: single-stage centrifugal pump,
E: multistage centrifugal pump,
F: screw pump,
G: chain pump,
H: mammoth pump
Which Pump?
drinking-water supply/ livestock watering: Volume = small to medium; Height = large to medium;
Piston pump (A), multistage centrifugal pump (E), eccentric screw pump (C), mammoth pump (H)
38
Thomas Ackermann November 2015
Which Pump?
Irrigation; Volume = large; Height = small
Single-stage centrifugal pump ( D), diaphragm pump (B), screw pump (F), chain pump (G);
often pumps that can handle dirty water
39
40
A: piston pump; B: diaphragm pump
C: eccentric screw pump; D: single-stage centrifugal pump
E: multistage centrifugal pump; F: screw pump
Total
pumped
head H
Rotational speed n
Thomas Ackermann November 2015
Important Aspects
Rated Wind Speed (1.4 ..1.6 of Vm)
Cut in Wind Speed;
Gearbox efficiency (reduces overall efficiency);
...
41
42
Thomas Ackermann November 2015
Operating Points
43
Piston pump Centrifugal pump
Starting moment for piston pump
44
Position of the crank drive
Rotational speed
Performance characteristics of
the wind turbine
Torque
Thomas Ackermann November 2015
Centrifugal Pump & Gear Box
45
Power PW of the
wind turbine
Rotational speed nW of the wind turbine
curve of operating
points
Wind Pumps ...
Can be a very easy and cost effective solution if appropriate designed!
46
Thomas Ackermann November 2015
47
Contents
Part 2: Wind Pump Systems
48
Part 3: Wind-Diesel Systems
Part 1: Small Wind Turbines
Thomas Ackermann November 2015
Wind Diesel Systems
In many remote locations in the world, power generation with diesel generators is the common;
Fuel prices, however, are often very expensive: InAustralia/China, fuel costs per kWh can reach up to 20 Uscents;
Wind power can be used as fuel saver!
49
Wind Diesel Systems
Different design concepts possible, from very basic to extremely complicated;
Costs versus reliability, power quality, lifetime of diesel generator & battery, redundancy of equipment.
Larger number of different concept are in use.
50
Thomas Ackermann November 2015
Diesel/ Battery
Diesel: Cascade Design;
Battery: Short term storage up to 5-10 minutes; Short lifetime due to large number of cycles, Extra building, Air-condition ?, Environmental problematic;
51
Practical Steps
Important: Define Max, Min and average load
52
Thomas Ackermann November 2015
Wind-Diesel-Battery Systems
53
System 1: Wind / Diesel Controlled by Frequency (Droop Mode)
The grid frequency is used as a measure for loadsharing between the WTG and the diesel genset;
If the load increases, speed of diesel drops and frequency decreases;
If diesel power output is less than 50 % than wind turbine would sense a rise and would start to pitch (reduce output), hence increase load on the diesel generator
54
Thomas Ackermann November 2015
System 1
Advantages
WTG can be installed without communication link;
Minimum load on diesel genset is ensured;
Disadvantages
Wind speed fluctuations affect grid frequency
Need