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Intrinsic properties of ultrasonic motor (high torque for low speed, high static torque, compact in size, etc.) offer great advantages for industrial applications. However, when load torque is applied, dead-zone occurs in the control input. Therefore, a nonlinear controller, which considers dead-zone, is adopted for ultrasonic motor. The state quantities, such as acceleration, speed, and position...
Intrinsic properties of ultrasonic motor (high torque for low speed, high static torque, compact in size, etc.) offer great advantages for industrial applications. However, when load torque is applied, dead-zone occurs in control input. Therefore, sliding mode controller, which is a nonlinear controller, is adopted for ultrasonic motor. The state quantities, such as acceleration, speed, and position...
Nowadays, a wind turbine generator (WTG) is required to provide control capabilities regarding an output power. Under this scenario, this paper presents a frequency control method by coordination control of the WTG and a battery using load estimation by a disturbance observer for isolated island. The load variation is reduced by the WTG using pitch angle control in low frequency domain and the battery...
As wind turbines continue to grow in size and flexibility and are deployed in more hostile environments, the need to develop advanced control schemes will be elemental to deliver the lowest possible energy costs. This paper explores controller design based on modeling the wind speed as a stochastic process, and the wind generating system (WGS) as a multi-mass system with a soft shaft linking the turbine...
Recent advancement in size and technology of wind energy conversion systems (WECSs) require sophisticated control systems to effectively optimize energy conversion and enhance grid integration. Doubly-fed induction generators (DFIG)-based WECS are the most promising and widely utilized technology. This study focuses on advanced controls development to identify and assess the critical loads and instabilities,...
The output power fluctuation of renewable energy power plants such as wind turbine generator and photovoltaic system result in frequency deviation and terminal voltage fluctuation. Furthermore, these power fluctuations also affect the turbine shafting of diesel generator and gas-turbine generators which are the main power generation systems in isolated islands. This paper presents a control strategy...
With the increasing trend of connecting high penetrations of wind energy conversion systems (WECSs) to the transmission networks comes the challenge of updating the grid code for the connection of megawatt-class wind turbines. Starting with each WECS entity in the wind farm, the specifications would require the ability to complement some of the power system control services-voltage and frequency control-currently...
Generally, PWM voltage source inverter (VSI) has been used for the variable speed permanent magnet synchronous motor (PMSM) drives. However, the PWM-VSI fed PMSMs has two disadvantages. Firstly, PMSMs cannot operate at the speed at which the motor terminal voltage exceeds voltage constraint imposed by the DC-link voltage. Secondly, the distortion of the voltage commands increase at the low speed,...
In this paper, a mathematical model of ultrasonic motors for speed control, which includes the nonlinearity and approximation of the dead-zone in control input, has been presented. Intrinsic property of ultrasonic motor (high torque for low speed, high static torque, compact in size, etc.) offers great advantages for industrial applications. However, speed property of ultrasonic motor has strong nonlinear...
This paper deals with the control of induction generator terminal voltage and power factor which controlled by adjusting reactive power using compensating capacitor. At first, the theoretical equations expressing induction generator terminal voltage and power factor are derived. Then, the compensating capacitor in terms of wind velocity is determined quantitatively. By using the proposed control method,...
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