Folie 1

1
Measurements of Doubly Fed Induction Generator
System With Optimised Fault Ride Through
Performance
2
Marketing Overview
Measurement 2.5MW Wind Turbine On Site

• Grid Code Requirements
• System Topology
• Control during Grid Faults
• Measurements
• Conclusions

3
Grid Code Requirements
Voltage Support
Fault Ride Through
4
Topology of Wind Energy System withDFIG and
4-Quadrant IGBT-Converter
5
Oscillating Torque Reduction during
Asymmetrical Grid Voltage Conditions
Constant torque
Oscillating torque
6
Test Bay Topology
750kW
750kW
2000kW
1500kW
7
Symmetrical Stator Voltage Sag to 9 Unominal
Stator voltage sag to 9 Unominal equals zero
voltage sag at point of common coupling
at nominal reactive current
Igrid Q1, negative overexcited Igrid
P1
Qgrid Pgrid,
8
Symmetrical Stator Voltage Sag to 0 Unominal
Fault ride through operation with stator short
circuit is technically possible
Igrid Q, negative overexcited Igrid
P
Qgrid Pgrid
9
Unsymmetrical Stator Voltage Sag to 9 Unominal
During asymmetrical grid voltage conditions
following operation modes are possible
b) reactive current support with limited
oscillating torque reduction
a) oscillating torque reduction with limited
reactive current support
Ustator - Ustator
Ustator - Ustator
Igrid Q, negative overexcited Igrid
P
Igrid Q, negative overexcited Igrid
P
10
Unsymmetrical Stator Voltage Sag to 9 Unominal
During asymmetrical grid voltage conditions
following operation modes are possible
b) reactive current support with limited
oscillating torque reduction
a) oscillating torque reduction with limited
reactive current support
11
Conclusions

• Compliance of wind energy systems with DFIG to
  actual grid code requirements, especially zero
  voltage ride through and voltage support
• No crowbar firing during fault ride through
  operation
• Converter system is actively controlled all the
  time during fault ride through operation,
  including voltage support and torque control
• Measured transient behavior of test bay
  comparable to wind turbine with nominal power of
  2-3 MW due to characteristic of testing
  generator