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This paper presents an investigation on the mechanism of the impact of the governor control on power system dynamics, and an introduction of boundary frequency. The well-known Hefferon-Phllips math model has been extended to include the math model of the turbine and its governor. By using this model the impact can be divided into the synchronizing and the damping torques. Based on the analysis of...
For solving the problem of high energy consumption of variable nozzle, the experimental study on lawn sprinkler for energy-saving and variable range of the precision spraying were carried out. In the case of square spraying, the functions of control period between nozzle inlet pressure, converter frequency and time were determined by tests. The motor frequency was regulated by the converter; the needed...
The last three decades have experienced an impressive growth in loads interfacing with the grid through power electronic devices. These include personal computers and most office equipment as well as industrial induction motors driven by variable frequency drives. The increasing importance of these non-conventional loads has an impact which is yet to be quantified and modeled systematically. This...
This paper focus on the harmony control of chopping frequency at low speed range in which SRM operates with voltage-PWM mode in time and frequency domains. The simulation results indicate that the total distribution of spectrum of phase current on nth harmony frequencies keeps the same shape when the ratio of chopping frequency to shaft speed is constant. Thus chopping frequency and shaft speed can...
In the control of high power induction machine drives, the effect of dead time should not be neglected in the low-speed range, especially in the condition of low loads because it can seriously distort stator current waveform and generate torque ripple. This paper presents some theoretical analysis for the dead time effect in open-loop control and current closed-loop control, and analyzes the mechanism...
This paper proposes a method of improving the stability in sensor-less control of permanent magnet synchronous motors. The control method for low-speed region is divided into two: One is a high frequency method, which involves a problem of reverse rotation once misdetection of the permanent magnet polarity should occur, and another one is a current drive method, which has a problem that phase and...
The most commonly used methods for design of the industrial speed controllers are: experimental, root locus, frequency and optimization methods. The most commonly used experimental methods are Ziegler-Nichols methods: stability margin and step response function. Ziegler-Nichols methods are applied for design of speed controller of PM brushless DC motor drive. Both methods give the controller parameters,...
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