Nowadays actual scientific problem of renewable energy is the problem of developing control systems, that ensure the generation of stable voltage in a changing environment. This paper presents a structure and methods of synthesis of control system development, which allow to decide the indicated problem. An electric subsystem of wind power plant is a well-known structure with well-known advantages, consisting mainly of double-fed induction generator (DFIG) and power converter in the circuit of rotor. Operation of the control system based on the original nonlinear mathematical model of DFIG in rotational "dq" coordinates, taking into account the nonlinear external and internal DFIG disturbances, such as inductances of coil winding, changes of coil winding resistances from temperature, etc. The study received adaptive control algorithms of the wind turbine output voltage parameters.

A robust direct flux and torque control (DFTC) technique of a doubly-fed induction generator (DFIG) for wind turbine applications (WTA) is presented in the paper. The main advantages of traditional DFTC control method are its simple structure, robust technique and good dynamic response compared to the field-oriented control (FOC). The use of a classical hysteresis comparator and a predefined lookup table will inevitably lead to select a nonoptimal rotor voltage vector in terms of reducing rotor flux errors, harmonic distortion (THD) current, and electromagnetic torque undulations. In this research work, a new approach of DFTC technique of DFIG based modified super-twisting algorithms (MSTA) and modified space vector modulation (MSVM) is developed by replacing the traditional lookup table and two hysteresis comparators. Theoretical principles of this method are presented along with simulation results. Analysis of DFTC-MSVM control scheme based MSTA controllers have been done in MATLAB/ Simulink environment. The machine (DFIG 1,5MW) is tested in association with a wind turbine. Simulation results are presented. The proposed DFTC control technique takes full advantage and the electromagnetic torque regulation objective of DFIG is confirmed by the numerical simulation results compared to the traditional DFTC control technique.

A new nonlinear controller for direct flux and torque control (DFTC) of a doubly-fed induction generator (DFIG) based on a single-rotor wind turbine (SRWT) using the fractional-order second-order continuous sliding mode (FOSOCSM) controller is presented in this paper. Three different controllers are proposed to control the electromagnetic torque and rotor flux of the doubly-fed induction generator driven by a single-rotor wind turbine. The main goal of the proposed DFTC control structure is to improve the quality of the electromagnetic torque and stator current of the SRWT system by reducing electromagnetic torque undulations, stator current, and rotor flux undulations in the DFIG-SRWT systems. The mathematical model of the DFIG has been described. The descriptions of the modified space vector modulation (MSVM) strategy and the proposed FOSOCSM controller have been presented. The DFTC-MSVM control structure with proposed FOSOCSM controllers has been described. This proposed strategy has been shown to be robust and stable against parametric uncertainties and load electromagnetic torque. The validity, robustness, and effectiveness of the proposed DFTC-FOSOCSM technique are demonstrated through simulation studies in the MATLAB® software environment. Numerical simulation results demonstrate that the proposed DFTC control scheme with proposed FOSOCSM controllers has a faster transient response than traditional DFTC and DFTC with classical SOCSM controllers. Also, it reduces ripples in both electromagnetic torque of stator current, and rotor flux significantly compared to the classic technique and DFTC with traditional SOCSM controllers.

Background: The direct flux and torque control are a robust, simple, and alternative approach control formulation that does not require decomposition into symmetrical components; the direct flux and torque control schemes have been proved to be preponderant for doubly-fed induction generators due to the simple implementation. Aim: This work presents the minimization of electromagnetic torque and rotor flux undulations of doubly-fed induction generators using fractional-order super twisting algorithms and modified space vector modulation techniques. Methods: The main role of direct flux and torque control is to regulate and control the electromagnetic torque and rotor flux of doubly-fed induction generators for wind turbine systems. The direct flux and torque control is a traditional control algorithm and robust technique. Fractional-order super twisting algorithms are a new and proposed nonlinear controller; characterized by a robust controller and a simpler algorithm, which gives a good harmonic distortion of current compared to other methods. Novelty: The A fractional-order super twisting algorithm is proposed. Proposed nonlinear controller construction is based on the traditional super twisting algorithm and fractional calculus to obtain a robust controller and reduces the electromagnetic torque and rotor flux undulations of doubly-fed induction generators. We use in our study a 1.5 MW doubly-fed induction generator integrated into a single-rotor wind turbine system to minimizes the electromagnetic torque, stator current, rotor flux undulations. As shown in the results figures using fractional-order super twisting algorithms ameliorate effectiveness especially minimizes the electromagnetic torque and rotor flux, and minimizes harmonic distortion of stator current (0.16 %) compared to the traditional control scheme. Results: As shown in the results figures using fractional-order super twisting algorithms ameliorate effectiveness especially minimizes the electromagnetic torque and rotor flux, and minimizes harmonic distortion of stator current (0.16 %) compared to the traditional control scheme. Conclusion: The direct flux and torque control are a robust, simple, and alternative approach control formulation that does not require decomposition into symmetrical components; the direct flux and torque control schemes have been proved to be preponderant for doubly-fed induction generators due to the simple implementation.

The paper considers the using of ground station operator’s software that provides the diagnosis of automatic control system of marine vehicles, based on the functional state monitoring of the system elements with depth to the type of failure. Also considers the use of neural networks for the issues solving of monitoring, control and state diagnostics of the actuators and sensors. This paper describes the principles of active fault tolerance and flexible functionality recovery of marine mobile vehicle’s control system