1. Modelling, Analysis, and Control Aspects of
a Rotating Power Electronic
Brushless Doubly-Fed Generator
Naveed ur Rehman Malik
Department of Electrical Energy Conversion
naveed.malik@ee.kth.se
2. NAVEED UR REHMAN MALIK, KTH 2
Outline
Different topologies
DFIG with slip rings
Introduce RPE-BDFIG
Dynamic model of the RPE-BDFIG
Closed-loop current control of the RPE-BDFIG
Experimental setup
Results
Conclusions
4. NAVEED UR REHMAN MALIK, KTH 4
Generator with Full-Scale Converter
Advantages
More rugged and reliable
Squirrel-cage induction generator
Direct-drive (permanent magnet)
Lower maintenance costs
Better low-voltage ride-through
Disadvantages
Larger size of the converter
Higher cost
Larger filters
5. NAVEED UR REHMAN MALIK, KTH 5
Slip-Ring Doubly-Fed Induction Generator
Advantages
Smaller power rating of the
converter due to limited
speed range
Cost effective
Disadvantages
High maintenance costs due
to slip rings/brushes
Brushes limit the generator
size
EMI can be troublesome
6. NAVEED UR REHMAN MALIK, KTH 6
Most famous topology in the family of wind generators
Slip-Ring Doubly-Fed Induction Generator
7. Carbon Brushes
Carbon brushes are replaced
every few months
Carbon dust is a problem in the
nacelle
Sparking between the brushes
and slip rings
NAVEED UR REHMAN MALIK, KTH 7
SOURCE:
http://www.engineersparadise.com/sixcms/
media.php/1463/Schleifringeinheit.jpg
8. NAVEED UR REHMAN MALIK, KTH 8
Rotating Power Electronic Brushless
Doubly-Fed Induction Generator
9. NAVEED UR REHMAN MALIK, KTH 9
Rotating Power Electronic Brushless
Doubly-Fed Induction Generator
Modes of Operation
Super-synchronous
Sub-synchronous
10. Advantages
Smaller converter due to
limited-speed-range
Lower maintenance cost
Lower EMI
Cost-effective
Disadvantages
Larger rotating mass
New technology
NAVEED UR REHMAN MALIK, KTH 10
Rotating Power Electronic Brushless
Doubly-Fed Induction Generator
11. Steady-state model
dq dynamic model
NAVEED UR REHMAN MALIK, KTH 11
Modelling the RPE-BDFIG
12. NAVEED UR REHMAN MALIK, KTH
12
Dynamic Model of the RPE-BDFIG
DFIG stator DFIG rotor Exciter rotor
13. NAVEED UR REHMAN MALIK, KTH 13
Closed-Loop Current Control of the RPE-BDFIG
Grid flux orientation
Phase Locked-Loop (PLL)
Two current controllers
One each for the DFIG and exciter rotor converter
Speed controller
DC-link voltage controller
24. NAVEED UR REHMAN MALIK, KTH 24
LVRT of RPE-BDFIG
LVRT investigation
Symmetrical and unsymmetrical voltage dips
Used E.oN grid code standards
Two techniques used
PRN
DVC
25. NAVEED UR REHMAN MALIK, KTH 25
Conclusions
Appropriate rotor voltage available from the exciter
Stable operation
Slip power recovery
Variable reactive power operation
Stable operation at synchronous speed
Converter size is around slip power rating of the machine.
Carbon brushes needs replacement every 10 months or so.
Converter size is around slip power rating of the machine.
Carbon brushes needs replacement every 10 months or so.
Converter size is around slip power rating of the machine.
Carbon brushes needs replacement every 10 months or so.
Before going into the details of the project i will just mention the conventional slip ring DFIG.
It is the most famous topology in the family of wind generators and has around 60% of the market of all wind generators.
So in order to remove slip rings and carbon brushes, they are replaced by a rotating converter and the exciter.
In a Generator mode, positive power factor implies capacitive and positive reactive power implies that it delivers reactive power. Therefore when load is increased, reactive power is capacitive in nature and is delivered to the grid.
In a Generator mode, positive power factor implies capacitive and positive reactive power implies that it delivers reactive power. Therefore when load is increased, reactive power is capacitive in nature and is delivered to the grid.
