scholarly journals Control model design to limit DC-link voltage during grid fault in a dfig variable speed wind turbine

2017 ◽  
Vol 68 (4) ◽  
pp. 274-281
Author(s):  
Cajethan M. Nwosu ◽  
Cosmas U. Ogbuka ◽  
Stephen E. Oti
Keyword(s):  
Wind Turbine ◽  
Control Model ◽  
Current Control ◽  
Loop Current ◽  
Model Design ◽  
Variable Speed ◽  
Power Circuit ◽  
Fault Ride Through ◽  
Variable Speed Wind Turbine ◽  
Speed Mode

AbstractThis paper presents a control model design capable of inhibiting the phenomenal rise in the DC-link voltage during grid- fault condition in a variable speed wind turbine. Against the use of power circuit protection strategies with inherent limitations in fault ride-through capability, a control circuit algorithm capable of limiting the DC-link voltage rise which in turn bears dynamics that has direct influence on the characteristics of the rotor voltage especially during grid faults is here proposed. The model results so obtained compare favorably with the simulation results as obtained in a MATLAB/SIMULINK environment. The generated model may therefore be used to predict near accurately the nature of DC-link voltage variations during fault given some factors which include speed and speed mode of operation, the value of damping resistor relative to half the product of inner loop current control bandwidth and the filter inductance.

scholarly journals Transient and steady state performance analysis of power flow control in a DFIG variable speed wind turbine

2017 ◽  
Vol 68 (1) ◽  
pp. 31-38
Author(s):  
Cajethan M. Nwosu ◽  
Stephen E. Oti ◽  
Cosmas U. Ogbuka
Keyword(s):  
Steady State ◽  
Performance Analysis ◽  
Wind Turbine ◽  
Power Flow ◽  
Variable Speed ◽  
Power Flow Control ◽  
Variable Speed Wind Turbine ◽  
Speed Mode ◽  
Transient And Steady State ◽  
Steady State Performance

Abstract This paper presents transient and steady state performance analysis of power flow control in a 5.0 kW Doubly-Fed Induction Generator (DFIG) Variable Speed Wind Turbine (VSWT) under sub synchronous speed, super synchronous speed and synchronous speed modes of operation. Stator flux orientation is used for the control of the rotor-side converter (RSC) and DFIG whereas the grid (or stator) voltage orientation is the preferred choice for the control of the grid-side converter (GSC). In each of the three speeds modes, power is always supplied to the grid through the stator of the DFIG. The magnitude of net power (stator power plus rotor power) is less than stator power during the sub synchronous speed mode; it is greater than stator power during the super synchronous speed mode while it is equal to the stator power during the synchronous speed mode. In synchronous speed mode, the rotor power is zero indicating that power is neither supplied to the grid from the rotor nor supplied to the rotor from the grid; here the magnitude of net power is equal to stator power. The simulation results thus obtained in a MATLAB/SIMULINK environment laid credence to the controllability of power flow reversal in a DFIG-VSWT through back-to-back power electronic converter.

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