1 Stephan Meier, Staffan Norrga, Hans-Peter Nee Department of Electrical Engineering Division of...
-
Upload
briana-johnson -
Category
Documents
-
view
216 -
download
0
Transcript of 1 Stephan Meier, Staffan Norrga, Hans-Peter Nee Department of Electrical Engineering Division of...
![Page 1: 1 Stephan Meier, Staffan Norrga, Hans-Peter Nee Department of Electrical Engineering Division of Electrical Machines and Power Electronics Royal Institute.](https://reader035.fdocuments.in/reader035/viewer/2022062518/56649de65503460f94ade9bf/html5/thumbnails/1.jpg)
1
Stephan Meier, Staffan Norrga, Hans-Peter Nee
Department of Electrical EngineeringDivision of Electrical Machines and Power Electronics
Royal Institute of TechnologyStockholm, Sweden
New topology for more efficient AC/DC converters for future offshore wind farms
Stephan Meier
Electrical Machines and Power Electronics
Norpie 04
New topology for more efficient AC/DC converters for future offshore
wind farms
![Page 2: 1 Stephan Meier, Staffan Norrga, Hans-Peter Nee Department of Electrical Engineering Division of Electrical Machines and Power Electronics Royal Institute.](https://reader035.fdocuments.in/reader035/viewer/2022062518/56649de65503460f94ade9bf/html5/thumbnails/2.jpg)
2
• VSC transmission
New topology for more efficient AC/DC converters for future offshore wind farms
Stephan Meier
Electrical Machines and Power Electronics
Norpie 04
Contents
• Adjustable speed wind turbine generators
• New AC/DC converter topologyPrinciple of operationCommutation principlesModulation algorithmBasic waveformsAdvantagesChallenges
• Conclusions
![Page 3: 1 Stephan Meier, Staffan Norrga, Hans-Peter Nee Department of Electrical Engineering Division of Electrical Machines and Power Electronics Royal Institute.](https://reader035.fdocuments.in/reader035/viewer/2022062518/56649de65503460f94ade9bf/html5/thumbnails/3.jpg)
3
• High Voltage Direct Current (HVDC) system based on Voltage Source Converters (VSC)
New topology for more efficient AC/DC converters for future offshore wind farms
Stephan Meier
Electrical Machines and Power Electronics
Norpie 04
VSC transmission - Principle
• No capacitive cable charging currents
• Provides isolation between the offshore installation and the mainland AC grid
![Page 4: 1 Stephan Meier, Staffan Norrga, Hans-Peter Nee Department of Electrical Engineering Division of Electrical Machines and Power Electronics Royal Institute.](https://reader035.fdocuments.in/reader035/viewer/2022062518/56649de65503460f94ade9bf/html5/thumbnails/4.jpg)
4
New topology for more efficient AC/DC converters for future offshore wind farms
Stephan Meier
Electrical Machines and Power Electronics
Norpie 04
VSC transmission - Advantages
ffarm is independent of fgrid: Frequency control of the wind turbine generators
DC cable can have any length required
Controllable active and reactive power flow
![Page 5: 1 Stephan Meier, Staffan Norrga, Hans-Peter Nee Department of Electrical Engineering Division of Electrical Machines and Power Electronics Royal Institute.](https://reader035.fdocuments.in/reader035/viewer/2022062518/56649de65503460f94ade9bf/html5/thumbnails/5.jpg)
5
New topology for more efficient AC/DC converters for future offshore wind farms
Stephan Meier
Electrical Machines and Power Electronics
Norpie 04
VSC transmission - Disadvantages
• High switching losses due to high-frequency PWM switching
• High costs for the complex converters
![Page 6: 1 Stephan Meier, Staffan Norrga, Hans-Peter Nee Department of Electrical Engineering Division of Electrical Machines and Power Electronics Royal Institute.](https://reader035.fdocuments.in/reader035/viewer/2022062518/56649de65503460f94ade9bf/html5/thumbnails/6.jpg)
6
• Low acoustic noise at low speed operation
New topology for more efficient AC/DC converters for future offshore wind farms
Stephan Meier
Electrical Machines and Power Electronics
Norpie 04
Adjustable speed wind turbine generators
a) Cut-in wind speed
b) Maximum output power
c) Constant output power
d) Cut-off wind speed
• Improved system efficiency
• Pitch control limits the power at rated conditions
• Reduced mechanical stresses and improved power quality
![Page 7: 1 Stephan Meier, Staffan Norrga, Hans-Peter Nee Department of Electrical Engineering Division of Electrical Machines and Power Electronics Royal Institute.](https://reader035.fdocuments.in/reader035/viewer/2022062518/56649de65503460f94ade9bf/html5/thumbnails/7.jpg)
7
New topology for more efficient AC/DC converters for future offshore wind farms
Stephan Meier
Electrical Machines and Power Electronics
Norpie 04
HVDC based VSC systems
1) New AC/DC converter topology
2) Direct-In-Line ASG (full size back-to-back VSC)
3) Doubly-fed induction generator ASG (back-to-back VSC is rated at approx. 20 % of rated power allowing a wide speed range)
4) Individual direct HVDC connection
![Page 8: 1 Stephan Meier, Staffan Norrga, Hans-Peter Nee Department of Electrical Engineering Division of Electrical Machines and Power Electronics Royal Institute.](https://reader035.fdocuments.in/reader035/viewer/2022062518/56649de65503460f94ade9bf/html5/thumbnails/8.jpg)
8
New topology for more efficient AC/DC converters for future offshore wind farms
Stephan Meier
Electrical Machines and Power Electronics
Norpie 04
New AC/DC converter topology
Installation in the wind turbine:- Line filter - MF transformer- Cycloconverter - Circuit breaker
Offshoreplatform:- Single-
phase VSC- Main MF
transformer- Main circuit
breaker
Distribution grid: - MF AC bus
![Page 9: 1 Stephan Meier, Staffan Norrga, Hans-Peter Nee Department of Electrical Engineering Division of Electrical Machines and Power Electronics Royal Institute.](https://reader035.fdocuments.in/reader035/viewer/2022062518/56649de65503460f94ade9bf/html5/thumbnails/9.jpg)
9
New topology for more efficient AC/DC converters for future offshore wind farms
Stephan Meier
Electrical Machines and Power Electronics
Norpie 04
Features
• Soft commutation is achieved for all semiconductor valves.
• The number of VSC phase legs is reduced to one.
• The cycloconverters enable variable speed operation of the wind turbines. Cheap and well-established fast thyristors are used.
• Single-phase MF transformers
![Page 10: 1 Stephan Meier, Staffan Norrga, Hans-Peter Nee Department of Electrical Engineering Division of Electrical Machines and Power Electronics Royal Institute.](https://reader035.fdocuments.in/reader035/viewer/2022062518/56649de65503460f94ade9bf/html5/thumbnails/10.jpg)
10
New topology for more efficient AC/DC converters for future offshore wind farms
Stephan Meier
Electrical Machines and Power Electronics
Norpie 04
Cycloconverter commutation
![Page 11: 1 Stephan Meier, Staffan Norrga, Hans-Peter Nee Department of Electrical Engineering Division of Electrical Machines and Power Electronics Royal Institute.](https://reader035.fdocuments.in/reader035/viewer/2022062518/56649de65503460f94ade9bf/html5/thumbnails/11.jpg)
11
New topology for more efficient AC/DC converters for future offshore wind farms
Stephan Meier
Electrical Machines and Power Electronics
Norpie 04
VSC commutation
![Page 12: 1 Stephan Meier, Staffan Norrga, Hans-Peter Nee Department of Electrical Engineering Division of Electrical Machines and Power Electronics Royal Institute.](https://reader035.fdocuments.in/reader035/viewer/2022062518/56649de65503460f94ade9bf/html5/thumbnails/12.jpg)
12
New topology for more efficient AC/DC converters for future offshore wind farms
Stephan Meier
Electrical Machines and Power Electronics
Norpie 04
Modulation
Carrier-based modulation:
- Maintain soft commutation
- Ensure proper transformer operation: Constant VSC commutation intervals
- Provide the desired PWM patterns for the cycloconverter
![Page 13: 1 Stephan Meier, Staffan Norrga, Hans-Peter Nee Department of Electrical Engineering Division of Electrical Machines and Power Electronics Royal Institute.](https://reader035.fdocuments.in/reader035/viewer/2022062518/56649de65503460f94ade9bf/html5/thumbnails/13.jpg)
13
New topology for more efficient AC/DC converters for future offshore wind farms
Stephan Meier
Electrical Machines and Power Electronics
Norpie 04
Simulated waveforms at rated operation (i)
Main transformer voltage and current
![Page 14: 1 Stephan Meier, Staffan Norrga, Hans-Peter Nee Department of Electrical Engineering Division of Electrical Machines and Power Electronics Royal Institute.](https://reader035.fdocuments.in/reader035/viewer/2022062518/56649de65503460f94ade9bf/html5/thumbnails/14.jpg)
14
New topology for more efficient AC/DC converters for future offshore wind farms
Stephan Meier
Electrical Machines and Power Electronics
Norpie 04
Simulated waveforms at rated operation (ii)
Cycloconverter phase voltage and current
![Page 15: 1 Stephan Meier, Staffan Norrga, Hans-Peter Nee Department of Electrical Engineering Division of Electrical Machines and Power Electronics Royal Institute.](https://reader035.fdocuments.in/reader035/viewer/2022062518/56649de65503460f94ade9bf/html5/thumbnails/15.jpg)
15
New topology for more efficient AC/DC converters for future offshore wind farms
Stephan Meier
Electrical Machines and Power Electronics
Norpie 04
Advantages
• Application of squirrel-cage induction generator.
• Cheaper single-phase MF transformers with reduced weight and volume.
• Significant reduction in series-connected IGBTs in the VSC.
• Significant reduction of switching losses.
• Application of comparably cheap and well-established fast thyristors in the cycloconverter.
![Page 16: 1 Stephan Meier, Staffan Norrga, Hans-Peter Nee Department of Electrical Engineering Division of Electrical Machines and Power Electronics Royal Institute.](https://reader035.fdocuments.in/reader035/viewer/2022062518/56649de65503460f94ade9bf/html5/thumbnails/16.jpg)
16
New topology for more efficient AC/DC converters for future offshore wind farms
Stephan Meier
Electrical Machines and Power Electronics
Norpie 04
Challenges
• Design of the MF transformer: Transformer insulation has to withstand high voltage derivatives.
• Effect of the square-wave MF voltage on the AC cables.
• Design of an appropriate design system:- on the wind farm level- on the converter level
![Page 17: 1 Stephan Meier, Staffan Norrga, Hans-Peter Nee Department of Electrical Engineering Division of Electrical Machines and Power Electronics Royal Institute.](https://reader035.fdocuments.in/reader035/viewer/2022062518/56649de65503460f94ade9bf/html5/thumbnails/17.jpg)
17
New topology for more efficient AC/DC converters for future offshore wind farms
Stephan Meier
Electrical Machines and Power Electronics
Norpie 04
Conclusions
• The proposed AC/DC converter offers full adjustable speed operation of the wind turbines.
• Low initial costs.
• Reduced switching losses due to soft commutation.
• The application of VSC transmission in the grid connection of wind farms becomes far more attractive.
![Page 18: 1 Stephan Meier, Staffan Norrga, Hans-Peter Nee Department of Electrical Engineering Division of Electrical Machines and Power Electronics Royal Institute.](https://reader035.fdocuments.in/reader035/viewer/2022062518/56649de65503460f94ade9bf/html5/thumbnails/18.jpg)
18
New topology for more efficient AC/DC converters for future offshore wind farms
Stephan Meier
Electrical Machines and Power Electronics
Norpie 04
Questions?
Acknowledgment:The authors would like to express their gratitude to Vind-Forsk and the Swedish Energy Agency for financial support.