NASHRIYYAH -I MUHANDISI -I BARQ VA MUHANDISI -I KAMPYUTAR -I IRAN, A- MUHANDISI -I BARQ
Year:2016 | Volume:14 | Issue:1|Papers Count:8

Nowadays, it is clear to everyone that climate change has posed a huge threat to human welfare. Hence, the growth of demand for electricity as well as the dependence of power sector to the fossil fuel sources has converted the electrical energy sector into one of the most important areas suitable for applying the restrictions and implementation of the solutions provided to mitigate greenhouse gases. Enacting different incentive-based support schemes pursuing the promotion of renewable energy sources along with emission reduction in power generation sector is treated as one the main provided solutions. In this paper, from various points of view, such as environmental issues, power sector investors’ profit and the surplus of electricity consumers, the effect of renewable penetration rate growth under implementation of incentive-based policies is evaluated in a long-term generation expansion planning framework by employing the concept of Bergson-Samuelson social welfare function. To achieve this aim, first, a comprehensive generation expansion planning model, faced by a generation company, is proposed, as the effect of one on the most popular policies, namely emission trading system, is incorporated into the model. As a mixed integer nonlinear programming problem, the model is solved through two different scenarios using the GMAS optimization package. Then, regarding the obtained optimized expansion strategies, aforementioned viewpoints are assessed.

Generators failure and generators break down can cause high financial consequences. For this reason, several concepts for the condition monitoring of generators have been developed. The purpose of this article is to collect significant generator data in order to form a comprehensive analysis by analytical hierarchy process (AHP) method. The AHP is a multi-criteria analysis approach, where is used in order to combine the results of online diagnostic methods and draw conclusions on the most probable failure. A fault diagnosis structure has been designed and several comparison charts have been generated. This trend led to the running generator probable failure, to be revealed. In this paper the circumstances of design and implementation of the LEMS structure with two simulation results are described.

This paper presents a new exact formulation which models all harmonics in Double Fed Induction Generator (DFIG). In this methodology, the harmonics which originate from rotor side converter, stator side and mechanical part are analyzed and their interactions are considered and a new model is extracted based on frequency components in electrical and mechanical parts. The proposed method expands previous analytical approach and phase angle/amplitude of frequency components take to be account.Since this model is derived from time domain relations between frequency components, it can be used in normal and faulty conditions. The proposed model is evaluated by some case study in MATLAB/SIMULINK software.

In this paper dual-loop control method is proposed for control of 400 Hz inverter. Resonant controllers are used in the outer loop to regulate the amplitude of fundamental harmonic and to remove the unwanted harmonics. To avoid phase delay and bandwidth degradation, proportional controller is used as the inner control loop. In this paper, hybrid digital design in discrete- and continuous-time domain is introduced to design the inner and outer control loops. To decouple the control system from the load current disturbances and to improve the dynamic performance, a feed-forward path is added to the dual-loop control structure. To reduce the noise of feed-forward path, a soft-derivative term is introduced which is optimized for 400 Hz frequency. To verify the system performance, several simulations have been carried out which shows satisfactory results under dynamic and steady state conditions. Finally, the experimental results of a 20 kVA hardware prototype is presented to confirm the validity of theoretical and simulation results.

The electrical connection between the load and source can be eliminated using inductive power transfer. Supplying AC Loads, such as V2G and single phase motors, is one of the many applications of IPT. To supply an AC load, the rectified output power of IPT should be delivered to an inverter. The sequential dc/ac/dc/ac conversions cause IPT efficiency decreases. To make an output AC voltage with acceptable THD, the carrier frequency of the PWM method should be several times the reference frequency which increases the switching loss. In this paper based on IPT gain-frequency characteristics, a new pulse frequency waveform synthesizing method (PFWS) has been presented. This method eliminates secondary inverter switching losses. It is shown that besides loss reduction, synthesized sinusoidal waveform at secondary of IPT, causes the Total Switching Device Power (TSDP) of secondary converters decrease, therefore their lifetime increase. Simulated and experimental results of the developed laboratory model which verify and illustrate the operation of the proposed method are presented.

Unified Power quality conditioner (UPQC) consists of back to back voltage source inverters. In UPQC combination of parallel and series active power filters are used to compensate for the nonlinear load current harmonics and voltage distortions, simultaneously. For appropriate performance of both converters and bidirectional power flow, the DC link voltage should be at least 1.41 times larger than the line to line voltage in the high voltage part of the system; i.e. the parallel active filter. One of the determining factors for the cost of semiconductors is the maximum tolerable voltage stress. The voltage stress of the series converter increases when the DC link voltage is high. In order to overcome this deficiency, a Z-source network is added to the common structure of back to back invertors in the UPQC. It will reduce the applied DC voltage to the series active power filters significantly and decrease the cost of manufacturing. In this structure, an impedance source network is used in an AC/DC inverter to produce a buck-boost effect. Additionally, dead time has been eliminated through the use of a Z source network in the parallel active filter and thus its performance and reliability has increased impressively. In this paper, a comparison study has been conducted through necessary simulations for the performance evaluation of the common and proposed structures. The total switching device power has been used as a criteria to confirm the manufacturing cost reduction in the proposed structure.

An interior permanent magnet motor is a good option for traction application related to the induction motor and switched reluctance motor because of high mechanical rigidity and low demagnetization risk. the design of this kind of motor is attractive for engineer despise the implementation cost of them in high constant speed power range (cpsr) is high. In this paper using combination of two ideas i.e. non-conventional air bridge and segmented permanent magnet a optimal design has been proposed. In this paper non-conventional air bridge is used for reducing the permanent magnet volume. The genetic algorithm has been applied to the goal function. Simulation results show the good performance of optimal design related the conventional design.

In this paper, a cooperative network consisting of one source, one relay, and one destination is considered. The source and the destination are both single-antenna systems, while the relay is equipped with N antennas and operates in decode-and-forward (DF) mode. We assume that there is no direct link between the source and the destination. We propose two beam forming methods at the relay to transmit the data to the destination. Beam forming is performed at the relay by the assumption of having two bit quantized information about the phase of all links between the relay and the destination. We derive an upper bound on bit error probability of the system and show that the proposed scheme achieves full diversity order. Simulation results illustrate that performance of the system in terms of bit error probability is better than some well-known scenarios and is close to some scenarios with ideal assumptions.