1. MATHEMATICAL MODELING
Virtual Inertial Response of Doubly Fed Induction Generator Wind Turbines
Elena van Hove1, Jonathan Devadason2
1Purdue University 2The University of Tennessee, Knoxville
Load decreases
DFIG power decreases and speed increases which is good
At about 65 s P looks bad
W looks good until 65 s
MOTIVATION
Conventional energy sources
Provide constant source of energy but are harmful to the environment
Can quickly adjust to fluctuations in load power demand
Use inertial response of synchronous generators
Inertial response is taking kinetic energy from generator’s rotor
Wind turbines
Predominately use induction generators
Do not have inertial response
Want to make controls that mimic inertial response
Common case of sudden frequency fluctuation is generator fall out
Deviation from 60 Hz is bad, machines heat up
Customer satisfaction is important
Simulation
I. Approximate variable initial values
Change in load
MATHEMATICAL MODELING
Equations derived from block diagram:
II. Find steady state values using derived equations
III. Apply load change at 50 seconds
Doubly-Fed Induction Generator (DFIG) equation derivation to model inertial response in MATLAB
34 state and algebraic variables
RESULTS
Inertial response very sensitive to KPF and KDF controllers
Important for frequency to stay near constant
All initial load values are Po= 0.5 p.u. and Qo= 0.1 p.u.
Example of load decrease
DFIG power appropriately decreases as synchronous generator speed increases
Figure 1: Block diagram of DFIG wind turbine model
Figure 2: Circuit realization of DFIG wind turbine model
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FUTURE WORK
Make robust conclusions on DFIG model
Investigate KPF and KDF controllers
Compare another virtual inertial response model
This work was supported primarily by the ERC Program of the National Science Foundation and DOE under NSF Award Number EEC
Other US government and industrial sponsors of CURENT research are also gratefully acknowledged.