NASHRIYYAH -I MUHANDISI -I BARQ VA MUHANDISI -I KAMPYUTAR -I IRAN, A- MUHANDISI -I BARQ
Year:2015 | Volume:13 | Issue:1|Papers Count:10

One of the most common electrical faults in Permanent Magnet Synchronous Motor (PMSM) is inter-turn fault in stator winding. At the incipient steps it seems not dangerous and so light, but spreading this fault can leads to irreparable Consequences. In this paper, the intelligent system is presented to protect PMSMs from this kind fault. At the first, intelligent protection system determine the condition of the motor (which can be: Normal, Phase-phase short circuit, Open circuit and Inter-turn fault conditions). If the system determines the faults then send an alarm to operator and also if the fault is inter-turn, it can determine the damaged phase. Obtaining results show that Probabilistic Neural Network can be the most reliable and robust protection system for PMSMs against internal faults, especially inter-turn faults.

The growing need of energy sources especially in industrial countries and the shortage of the fossil resources cause a great concern in many countries. Considering that in some periods of the day the energy price is increased, Demand side management is one of the solutions that is implemented. The major change in demand side management is consideration of consumers' response to energy price variations. This paper investigates the effect of demand response implementation on cost reduction in stochastic security constraint unit commitment. Uncertainties in power system such as transmission lines and power plants outage is considered in the paper Considering that the simultaneous implementation of stochastic security constraint unit commitment and demand response is a complex and nonlinear problem that contain Continuous and discrete variables, the mixed integer programming is being used. Proposed method is simulated in simple 3 bud system and IEEE RTS 24 bus system and the results analyzed in the paper.

This study compares Direct Torque Flux Control (DTFC) performance of a three-phase Induction Motor (IM) and its equal Line-Start Permanent Magnet Synchronous Motor (LSPMSM). Simulation results of line-starting DTFC method of an IM and its equal LSPMSM (for both normal and voltage sag conditions) is compared and analyzed. In addition, field weakening region is evaluated. The advantages of the discussed control strategy over line-starting are also investigated for LSPMSM.

Increasing power transfer capability of existing transmission lines is one of the key issues in the power systems. Inter-area oscillations have effect on the power transfer capability and decrease the network efficiency. On the other hand, FACTS devices can be used to increase the power transfer capability by damping the inter-area oscillations. This paper proposes a Linear Matrix Inequality (LMI) based robust controller design to generate an additional stabilizing signal for a Static VAR Compensator (SVC) in order to increase damping of the inter-area modes. Wide Area Measurement (WAM) has been employed by the controller which is designed based on the H∞ mixed-sensitivity synthesis method. The effectiveness of the method is investigated by a test system consisting of 16 numbers of generators, 68 buses and 5 areas. The results show good and robust performance of the controller in damping the oscillations.

In single-stage single-phase power factor correction converters, the time of dynamic response and input current THD are in conflict with each other. The main purpose of this paper is to improve the dynamic response of the converter along with reducing its input current THD. To achieve these goals, two multi-objective optimization methods based on evolutionary algorithms including; SPEA and NSGA-II were used to design a PI compensator coefficients in the indirect current control technique for PFC rectifier. The integral and fractional-order PI compensators were designed, respectively. The obtained results showed the superiority of the fractional-order PI compensator. To investigate the optimization problem, the dynamic response to changes in load and reference voltage was considered. The comparison between the optimization algorithms showed that each algorithm may have better performance than the other one according to the used objective functions. It means that neither had an absolute superiority.

Due to increasing number of inverter based distributed generation resources in electric power systems, improving the quality and performance of them are necessary. In this paper a new current scheme is presented to inject sinusoidal current to the grid with following grid voltage conditions: sinusoidal voltage, distorted voltage and unbalance voltage. The proposed control scheme includes two sections: 1) Determination of sinusoidal reference current considering grid voltage condition; 2) current controller to track reference current. The proposed reference current determination algorithm in comparison with other algorithms, such as Park method is implemented easier and has faster dynamic response. The proposed current controller is implemented in the stationary reference frame and does not require the use of multiple controllers and coordinate transforms to compensate the harmonics. This control strategy needs tuning of only one variable, hence compared with other control methods requires less computational burden for practical implementation. Simulation results confirm the effectiveness of the proposed control method.

This paper e-multi objective genetic algorithm variable (eV-MOGA) to optimize cost of generation, emission and active power transmission loss of flexible ac transmission systems (FACTS) device-equipped power systems. In the proposed approach, optimal power flow problem is formulated as a multi-objective optimization problem. FACTS devices considered include thyristor controlled series capacitor (TCSC). The proposed approach has been examined and tested on the modified IEEE 57-bus test system. The results obtained from the proposed approach have been compared with those obtained from nondominated sorting genetic algorithm-II, multi-objective differential evolution.

High voltage chargers are being used in the equipments such as electrical vehicles, uninterruptible power supplies and aircrafts. The converter introduced here is based on bi-directional boost topology. The output voltage of batteries set is larger than the input source voltage amplitude, and this converter can transfer the energy both from the source to the batteries bank and vice versa. Input source voltage is sine wave and the output voltage is DC. Both conversion of AC-to-DC and DC-to-DC is performed in one stage and the control scheme of switches is based on hysteric control method to achieve the unity power factor. One can use the electrical equations presented here to define the converter and EMC filter elements value. Finally, simulation results performed on a typical converter show the control method authenticity and effectiveness of the analyses presented here. Also some suggestion for the future works is proposed.

Construction of wind farms rise for wind energy capture as a renewable energy around the world. The purpose of wind farm layout optimization, absorb maximum energy from wind farms. In this paper, a new hybrid algorithm is presented to maximize the expected energy output. Considerations of algorithm wake loss, which is based on wind turbine location and wind direction. The proposed model is illustrated with a scenario of the wind speed and its direction distribution of windy sites and is compared with ant colony algorithm and evolutionary strategy algorithm in six steps layout. The results show that the combination of ant colony algorithm and genetic algorithm performs better than existing strategies based on maximum values of the expected energy output and wake loss.

Spatial diversity is one of the most effective techniques to combat fading in wireless channels that can be implemented through antenna arrays. In this paper the hybrid decode-amplify-forward protocol with best relay selection (HDAF-S)in a cooperative system with multiple parallel relays with independent non-identically channels is considered and tight upper and lower bounds on bit error rate (BER) of this protocol is derived. It is shown that the BER of this protocol outperforms the BER of amplify and forward (AF) protocol but cannot exceeds the performance of decode and forward (DF) protocol. Then through asymptotic analysis for high SNR regime, it is shown that the HDAF-S protocol achieves full diversity order. Then the BER performance of HDAF protocol with n-th best relay selection (HDAF-nS) in independent and identically distributed channels is analyzed and tight upper and lower bounds on the BER are derived. Asymptotic analysis shows that this protocol cannot achieve full diversity order and it is shown that the diversity order decreases as n increases. The analytical results are validated through simulations.