مجله مهندسی برق و الکترونیک ایران
سال دهم شماره 2 (پاییز و زمستان 1392)

Demand response (DR) has many beneficiaries in the electricity market. There are independent players who are interested in DR, which include: transmission system owners, distributors, retailers, and aggregators. In this paper DR is introduced as a tradable commodity that can be exchanged between DR buyers and sellers in a pool-based market which is called demand response exchange (DRX). DRX operator (DRXO) collects DR offers and bids from the buyers and sellers. In this paper, a novel approach has been presented for buyers to bid in a DRX market. Also a dynamic approach has been proposed for DR sellers’ participation in DRX market. In the proposed approach, the buyers should forecast their loads and energy market prices. An ARIMA method is used for these forecasts. Then, a dynamic approach is proposed for DR sellers in order to maximize their profits. The proposed scheme is tested using Spain market data. The results show the efficiency and accuracy of the proposed approach.

Voltage control is one of the imperative issues in the smart distribution control system. While traditional distribution network is equipped with communication and monitoring equipment, the online voltage control can be perfectly achieved. With using these smart gird technologies, the distribution voltage control schemes should carry out intelligently and cover the undesirable effect of high penetration of renewable distributed generation. This paper presents a new approach that improved the conventional voltage control models. The proposed approach needs measuring and communication equipment less than other methods, and can cover the renewable distributed generation impact on distribution network. The proposed online voltage control model was tested on typical distribution network. The results show that the proposed model can stabilize voltage in predefined range in different consumer load fluctuation conditions and variable renewable generation levels.

This paper presents the application of radial basis neural networks to the development of a novel method for the condition monitoring and fault diagnosis of synchronous generators. In the proposed scheme, flux linkage analysis is used to reach a decision. Probabilistic neural network (PNN) and discrete wavelet transform (DWT) are used in design of fault diagnosis system. PNN as main part of this fault diagnosis system and DWT are combined effectively to construct the classifier. The PNN is trained by features extracted from the magnetic flux linkage data through the discrete Meyer wavelet transform. Magnetic flux linkage data is provided by a FEM (Finite Element Method) simulation of a real synchronous generator and estimated by generalized regression neural network (GRNN). Then PNN is tested with experimental data, derived from a 4-pole, 380V, 1500 rpm, 50 Hz, 50 KVA, 3-phase salient-pole synchronous generator.

In this paper, a new topology is proposed for three-phase to single-phase matrix converters, where more voltage levels are produced in the output in comparison with the conventional topologies. In addition, a new control method based on minimum error between the generated and the desired output voltages is proposed for three-phase to single-phase matrix converters. In the proposed control method, the output voltage is generated by the mixture of different pieces of the input voltages. In other words, by applying this method, the matrix converter operates like a multilevel converter without requiring to any extra elements. Due to the proposed control method, the desired output voltage can be generated with an acceptable accuracy even with unbalanced and significantly distorted input voltage waveforms. The other advantage of the proposed control method is reduction of number of switching which allows low speed semiconductors application in the structure of bidirectional switches required by matrix converters and also reduction in switching losses. Using this strategy, the stresses on load are significantly reduced. As a result, the electromagnetic interference (EMI) is considerably decreased in comparison with the other conventional control methods. Simulation results in PSCAD/EMTDC software and experimental results show that the proposed control method operates correctly and confirm the perfect performance of the proposed topology.

The space environment consists mainly of high-energy charged particles, such as protons, electrons and heavy ions. They are originating from several sources including galactic cosmic radiation, solar flares and van Allen belts. High energy electromagnetic radiation and neutrons have also been measured on spacecraft. Although shielding can reduce the effect of space radiation it cannot be eliminated completely. So the proper evaluation is the key to improve the system performance in space environment. In this paper, the space environment analysis and evaluation for High Altitude Satellites reported with an emphasis on radiation analysis as being the most significant source of space product failures. When there is no shielding, the forecasted value of Total Ionizing Dose (TID) is 109 rads (Si) and non-ionizing Displacement Damage Dose (DDD) is 1014 MeV/g(Si) for 18-year mission lifetime of high altitude satellite.

The robustness property can be added to DSC system at the expense of reducing performance, i.e., increasing the sum-rate. The aim of designing robust DSC schemes is to trade off between system robustness and compression efficiency. In this paper, after deriving an inner bound on the rate–distortion region for the quadratic Gaussian MDC based RDSC system with two encoders, the structure of the RDSC system with three encoders and more generally with an arbitrary number of encoders are considered. Then inner bounds on the rate–distortion region for both MDC and MLC based Gaussian RDSC systems with an arbitrary number of encoders are derived. Finally, a practical coding approach for both MDC and MLC based Gaussian RDSC systems with an arbitrary number of encoders is proposed. The proposed approach is based on the multilevel Slepian-Wolf coded quantization framework. The approach is applied on the systems with two and three encoders and then extending and applying the approach on the systems with the number of encoders greater than three is straightforward. The obtained results are promising and satisfy the inner bounds for both rates and distortions for both sides and central decoders. This work paves the way of practical RDSC design in a general case.