Designing optimal controllers for doubly fed induction generators using a genetic algorithm

Inst. de Tecnol., Univ. Fed. do Para, Belem
IET Generation Transmission & Distribution (Impact Factor: 1.41). 06/2009; DOI: 10.1049/iet-gtd.2008.0239
Source: IEEE Xplore

ABSTRACT This work presents a design procedure based on evolutionary computation, more specifically on a genetic algorithm combined with the formal pole placement project, to obtain optimal controllers to the rotor-side converter of doubly fed induction generators (DFIGs), in variable-speed wind generation systems connected to the electrical grid. With this procedure it is intended to improve the global system dynamic behaviour during and after the fault period, also increasing the transient stability margin of the power system and the fault ride-through capability. The control action of the DFIG converters is accomplished by proportional and integral controllers, whose gainspsila adjustment is not a trivial task, because of the high complexity of the system. The results obtained confirm the efficiency of the proposed control design procedure.

  • [Show abstract] [Hide abstract]
    ABSTRACT: Closed-loop control provides a challenge for fault diagnosis in electric machines due to inherent compensation provided by the controller. This paper presents a method to detect static and dynamic air-gap eccentricities in doubly-fed induction generators (DFIGs) operated for closed-loop stator power control. A model of the eccentric machine is first developed using modified winding function theory (MWFT) and a suitable reference frame is chosen so as to decouple the flux equations and dynamically simulate the machine. A modified control technique is proposed to enable detection of air-gap eccentricities. The technique helps detect and differentiate or isolate this fault from grid-voltage unbalances and stator and rotor electrical faults that produce similar effects. The proposed method looks at low frequency fault signatures which can be detected using the DSP controller that is part of the drive. The effectiveness of the proposed control is verified using simulations and preliminary experiments performed on a laboratory set-up.
    Electric Machines & Drives Conference (IEMDC), 2011 IEEE International; 01/2011
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: In this paper, a combined vector and direct power control (CVDPC) is proposed for the rotor side converter (RSC) of doubly fed induction generators (DFIGs). The control system is based on a direct current control by selecting appropriate voltage vectors from a switching table. In fact, the proposed CVDPC enjoys the benefits of vector control (VC) and direct power control (DPC) in a compacted control system. Its benefits in comparison with VC include fast dynamic response, robustness against the machine parameters variation, lower computation, and simple implementation. On the other hand, it has benefits in comparison with DPC, including less harmonic distortion and lower power ripple. An extensive simulation study, using MATLAB/Simulink, is conducted on a 9-MW wind farm composed of six 1.5-MW DFIG-based wind turbines. The performance of the proposed CVDPC method is compared with both VC and DPC under steady-state and transient conditions. Simulation results confirm the superiority of the CVDPC over either VC or DPC.
    IEEE Transactions on Sustainable Energy 01/2014; 5(3):767-775. · 3.84 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: It is proposed in this paper a methodology to obtain optimal controllers gains for the rotor-side converter of doubly fed induction generators (DFIGs) using a genetic algorithm approach. The main objective is to enhance the operational security and robustness of the power system, by a more effective contribution of the DFIG controllers to the system controllability. To reach this goal, the crow-bar protection scheme is activated during the fault period when severe voltage sags occur in order to maintain the rotor-side converter connected to the DFIG. Immediately after the fault is cleared the crow-bar protection scheme is deactivated and simultaneously the rotor-side converter optimal controllers are turned on which permits the improvement of the converter ride-through capability and also contribute to enhance the overall power system stability margin. To validate the optimal proposed methodology several simulation results were obtained using a real electrical network which are presented in the paper.
    Bulk Power System Dynamics and Control (iREP) - VIII (iREP), 2010 iREP Symposium; 01/2010