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The paper presents numerical simulation results and experimental data used for modeling a hybrid step motor (HSM). Two different HSM models have been developed starting from available technical data of a HSM (2-phase, bipolar, frame size 56.4 mm). One of the models is adequate for analyzing the HSM response to different control strategies, while the second one can be used for performing an electromagnetic...
In this paper is presented a solution for optimal operation of the Francis turbine, the most used hydro energy converter in small hydro plants. As the efficiency of this turbine is highly dependent from the water flow, which generally has a large variation, variable speed operation was chosen. Due to the fact that all hydro generators are AC machines, the connection to the 50 Hz power grid can be...
The paper presents a variable speed solution for optimal operation of a group of small water turbines integrated in a medium voltage AC grid. As the efficiency of hydro machines is dependent on the water flow, which usually exhibits a large variation, operation at variable speed is considered. Due to the fact that all hydro generators are AC machines, the connection to the 50 Hz power grid can be...
This paper proposes a method for optimal placement of phasor measurement units (PMUs) for measuring the states of a power system. A method to compute the measurement uncertainty associated with the estimated states is also illustrated in the paper. The PMU placement strategy ensures complete observability of the power system states for normal operating conditions, as well as under the loss of a single...
The optimal control of the transient state of the electrical drive systems with DC and AC motors is presented. Similar interesting results for different motor types are obtained. A simple implementable suboptimal solution is proposed.
In this paper, one application targeting a small-scale DC network supplying signal processing laboratory (personal computers, universal motors and other low-voltage, low-power loads) is proposed, in order to analyze the technical interconnecting possibilities of isolated power systems. As a first step, simulations using the already implemented network elements models in DIgSilent were performed in...
In the paper, a new approach on the model of the broken rotor bars and rotor rings of the induction generators used in micro hydro power plants is proposed. Any physical asymmetry of the rotor, as a broken bar or a broken ring directly affects the stator current and the machine torque by distorting the corresponding waveforms. The analysis of simulation results and experimental data obtained for different...
The paper presents the results referring to the dc link voltage control of an induction generator/PWM converter system. This system can be used for the renewable energy sources in isolated areas. The voltage control is carried out with an adequate flux control based on an indirect rotor field oriented control.
The advent of higher voltages in automobiles constitutes an opportunity for new electrical features and systems. A combined starter-generator is one of them, because provides greater electrical generation capacity and improves the fuel economy and emissions. The paper describes a performing test facility to evaluate the behavior of the control structure of an indirect field-oriented induction machine...
The paper studies a decoupling control method for induction motor drive supplied by a voltage source inverter. The proposed method is based on general theory of decoupling linear systems modeled by state variables and has certain advantages because leads to a decoupled system independent of motor parameters.
On line estimation of the battery state of charge may be realized through on optimal Kalman Filter, based on the battery model. In this paper is presented a method to obtain physical battery parameters. The proposal method is based on coefficients estimation of the continuous-time model.
A DC grid with different type of generators and load is presented. It is considered an islanded and grid connected operation. A low voltage laboratory model is simulated and tested and is expected in the future the results to be extended to high voltage applications. It is demonstrated that the solution can have not only scientific but also commercial viability.
The advent of higher voltages in automobiles constitutes an opportunity for new electrical features and systems. A combined starter-generator is one of them, because provides greater electrical generation capacity and improves the fuel economy and emissions. The paper presents a control structure of an indirect field-oriented induction machine dedicated to act as integrated starter-generator. Test...
The exploitation of renewable sources is expected to become the most promising solution to the environmental issues and to the permanent increase of prices of the fossil energy. Since most of renewable energy sources are widely distributed and the energy converters generally do not provide electric power at main grid frequency and voltage, a DC bus is suggested to be used for integrating them into...
We have synthesized coloured monomer structures characterized by the simultaneous existence of a polarizable double bond and an extended chromophore. The polymerization and copolymerization of these monomers have been tested with styrene and methyl methacrylate. The third-order nonlinear optical (NLO) properties of different samples have been studied from their solutions using chloroform as solvent...
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