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The increasing penetration of variable speed wind turbines which use the traditional controllers reduces the inertia of power systems. Consequently, the maintenance of the frequency stability of power systems would be an important challenge. Currently, droop and inertial control methods have been used in variable speed wind turbines to control the frequency of the power network. Adjusting the gains on the droop and inertia control loops is very influential on the performance of wind turbines. However, due to the variable wind speed and power system conditions, the adjustment of the control coefficients which produces the best response in all situations seems to be impossible. In this paper, a new method for the adaptive adjustment of droop and inertia control loop gains in the doubly fed induction generator is presented. In order to eliminate the defects and problems of the power system and wind turbine modeling, it is also proposed to use the data-driven method, which only operates based on the input and output of the system. The second derivative of the error can be used to provide the adaptive adjustment of the droop and inertia control loop gains. This is done to enable faster control and to prevent frequency drooping. In the proposed control method, through implementing the K-vector nearest neighborhood, the output of the next moment is estimated. Then, the coefficients of the frequency control loops are adjusted adaptively, using the Hessian matrix. Simulation results demonstrated the proper performance of a data-driven based adaptive approach to increase the frequency nadir and to decrease the frequency variations of the power system in a steady state and a transient state. [ABSTRACT FROM AUTHOR]

Five-phase permanent magnet synchronous motors (PMSM) have special applications in which highly accurate speed and torque control of the motor are a strong requirement. Direct Torque Control (DTC) is a suitable method for the driver structure of these motors. If in this method, instead of using a common five-phase voltage source inverter, a three-phase to five-phase matrix converter is used, the low-frequency current harmonics and the high torque ripple are limited, and an improved input power factor is obtained. Because the input voltages of such converters are directly supplied by input three-phase supply voltages, an imbalance in the voltages will cause problems such as unbalanced stator currents and electromagnetic torque fluctuations. In this paper, a new method is introduced to remove speed and torque oscillator factors. For this purpose, motor torque equations were developed and the oscillation components created by the unbalanced source voltage, determined. Then, using the active and reactive power reference generator, the controller power reference was adjusted in such a way that the electromagnetic torque of the motor did not change. By this means, a number of features including speed, torque, and flux of the motor were improved in terms of the above-mentioned conditions. Simulations were analyzed using Matlab/Simulink software. [ABSTRACT FROM AUTHOR]