IRANIAN JOURNAL OF ELECTRICAL AND COMPUTER ENGINEERING (IJECE)
Year:2011 | Volume:10 | Issue:1|Papers Count:8

This paper presents an application of layered ANN controller to study load frequency control problem in power system.The objective of control scheme guarantees that steady state error of frequencies and inadvertent interchange of tie-lines are maintained in a given tolerance limitation. The proposed controller has been designed for a two-area interconnected power system. Only one ANN, which controls the inputs of each area in the power system together, is considered. In this study, back propagation-through time algorithm is used as ANN learning rule. The performance of the power system is simulated by using conventional integral controller and ANN controller, separately. For the first time comparative study has been carried out between SMES and CES unit, all of the areas are included with SMES and CES unit separately. By comparing the results for both cases, the performance of ANN controller with CES unit is found to be better than conventional controllers with SMES, CES and ANN with SMES.

In this paper, an effective topological and primitive impedance based distribution power flow algorithm is developed for both balanced and unbalanced distribution systems. This method fully exploits the radial structure of the network and solves the distribution load flow directly. Using this concept and primitive impedances of the lines, only diagonal elements of the Distribution Load Flow (DLF) matrix are computed and stored in single dimension vectors to obtain the distribution load flow solution. Unlike other traditional methods, the proposed approach does not require any LU decomposition or Bus admittance matrix. It is robust, time-efficient and needs very less memory for any size of the distribution system. The proposed method is tested on a unbalanced practical Indian distribution system and also on various standard IEEE test systems including weakly meshed distribution system. Results are quite promising and the method has great potential application in the distribution automation.

This manuscript presents the patterns of surface discharge currents due to pressure influence on the porcelain insulator specimen. It was subjected by the high voltages in a hermetically sealed chamber, where the pressure could be adjusted and measured simultaneously. The applied voltage and discharge current waveforms were recorded by a storage digital oscilloscope, transferred and saved to a computer. The discharge current waveforms were analyzed by using FFT, correlation coefficient and principal component analyses.The yielded discharge currents were in intermittent conditions. After the fundamental, the second highest harmonics was third. The discharge current amplitude increased significantly as the pressure reduced. The characteristics between discharge current and applied voltage magnitudes were more extremely non-linear as the pressures reduced, especially they were lower than the atmospheric pressure. The discharge breakdown voltage increased as the air pressure rose. It required a voltage magnitude threshold to be discharge.Almost harmonics had the negative correlation coefficients on the pressure, except the THD which had 0.45. The increasing THD was more dominantly caused by the increasing first harmonics which was slighter than the increasing remaining harmonics.

This paper presents a new fault location method for radial distribution networks with distributed generations.The proposed fault location algorithm uses the voltage and current data obtained by digital fault recorder installed at the head of the network main feeder, with or without the data from any digital fault recorders installed at DG connection points. The algorithm is based on fundamental frequency calculations and includes novel subroutines of current calculation of DG contained laterals and average loading factor and power factor estimation of the network transformers to solve the fault location problem. The method has been tested by simulation studies using EMTP on a 205-node 20kV radial distribution network containing three DG's for different data acquisition scenarios. The results verify accuracy of the method under different fault conditions even with only one measuring point at the head of the main feeder.

Congestion management is one of the major tasks performed by system operators in deregulated environment to ensure the secure operation of transmission system. Congestion should be alleviated as fast as possible since it may lead to tripping of overloaded lines, consequential tripping of other lines, and in some cases to voltage stability problem. This paper proposes an intelligent technique based on neural network for on line congestion management in a pool based electricity market. The control action strategies to limit line loading to the security limits are by means of minimal adjustments in generations from the initial market clearing values. The training data are generated by solving the proposed congestion management problem for wide range of real and reactive power of loads with critical line outage using Differential Evolution (DE) as an optimization tool. The effectiveness of the proposed method is tested under different loading conditions with contingency in IEEE 30 Bus system. Test results validate the potential of the proposed method.

A comparative study of passive and active waveshaping filter (current-source fed CSF switch mode rectifier SMR converter supplied from single-phase AC supply) presented in this study. Active harmonic filter (boost converter) used to reduce the harmonics at the main supply by controlling the duty cycle of the filter. Passive waveshaping filter reduce the harmonics at the supply in a simple way. The two circuits are designed and implemented using MATLAB/Simulink®. It is found that use of active harmonic filter increases the input power factor approximately from 0.63 to 0.81. While, in passive filter the PF increased to 0.86. Moreover, total harmonic distortion THDi was reduced in passive method more in comparison with active one.

In this paper a novel dual-band printed diversity monopole antenna integrated on a PCMCIA network card is proposed and studied. The antenna which consists of two monopoles with symmetric configuration operates at 2.4/5.2 GHz WLAN with very high isolation over two operational bands. The effects of some important parameters of proposed antenna are studied. The diversity performance is evaluated by calculating the envelope correlation coefficient and mean effective gain (MEG) of each element. These evaluations show that the proposed diversity antenna can provide spatial and pattern diversity to combat multi-path fading in mobile devices and WLAN applications.

This paper deals with the simulation of eight bus system having fixed capacitor and thyristor controlled reactor. The system is modeled and simulated using MATLAB. The simulation results are presented. The power and control circuits are simulated. The current drawn by the TCR varies with the variation in the firing angle. The simulation results are compared with the theoretical results.