The Modares Journal of Electrical Engineering
Volume:12 Issue: 2, 2012

This paper illustrates the application of S-transform and continuous wavelet transform (CWT) for fault location in combined overhead line and cable distribution networks. The high frequency transient signals originated by faults are analyzed using S-transform and CWT. The S-transform is found to be applicable in transient based fault location in distribution networks. This technique is an expansion of wavelet transform method and is based on a moving and scalable localizing Gaussian window. Taking into account this fact that the signal energy of faults has high amplitude around certain frequencies, the fault location can be identified considering the relationship between these frequencies and so-called path characteristic frequencies related to the fault traveling waves. The transient voltage signal energy is calculated using S-Transform and CWT. In order to demonstrate the effectiveness of the proposed method, the distribution networks with only overhead lines, as well as a combined system (consisting of the overhead lines and underground cables) have been studied. The IEEE 34-bus test distribution network is simulated in EMTP-RV software and the relevant S-transform and CWT analyses are carried out in MATLAB coding environment

In this paper, a new method for determining position and orientation of a coordinate system using its image is presented. This coordinate system is a three dimensional non-orthogonal system in respect to the two dimensional and orthogonal camera coordinate system. In real world, it’s exactly easy to select three directions on an object so that they don’t be orthogonal and on a plane. The image of this non-orthogonal coordinate system on the camera image plane is a two dimensional coordinate system. This image is obtained by a nonlinear mapping between three dimensional worlds coordinate and two dimensional image coordinate. In this paper, we review geometric relationships between a direction of a vector on the object and its image that was presented in paper [18] months ago. Then, using these relationships for three arbitrary non-orthogonal directions which are not on a plane, a system of 15 nonlinear equations is established, and by solving it, nine unknowns are extracted. Because of the importance of the sign of these unknowns to determine true lengths and angels, it’s essential to run this system of nonlinear equations in eight cases and then best answer with right signs can be extracted. The results of this theory have been examined using simulation and programs. In paper [18] we have to select three orthogonal vectors on an object. Since world is 3D, in some cases it is exactly difficult to choose all three directions with proper length and maybe we have to choose third vector (which is in depth) with a short length and it increase errors in finding position and orientation. But in this paper we don’t limit directions to be orthogonal, so all three directions can be in proper length and it decreases the errors.

In this paper, a new high dynamic range Digitally-Controlled Oscillator (DCO) for All-DPLL systems is proposed. The proposed DCO is based on using a ΔΣ modulator as a Digital-to-Analog converter. Using ΔΣ DAC can provide a very high resolution (18-bit) control on the DCO. The ΔΣ DAC output is a 2-level pulse signal that needs to be filtered for cancelling the out of band shaped noise. The used ΔΣ modulator is a 4th order MASH ΔΣ modulator working with the OSR of 128 and the sampling frequency of 450MHz. the proposed DCO is used in a PLL to synthesize the frequency in the range of 1700MHz to 1800MHz for GSM-1800 application. The achieved phase noise for this PLL based synthesizer in whole the range is -115 dBc/Hz at the offset frequency of 500 kHz. The designed ADPLL including the DCO is simulated in ADS with 0.18µm CMOS technology.

to enhance the closed loop performance in presence of disturbance, uncertainties and delay a double loop mixture of MPC and robust controller is proposed. This double loop controller ensures smooth tracking for a 3-axis gyro-stabilized platform which has delay intrinsically. This control idea is suggested to eliminate high frequency disturbances and minimize steady state error with minimum power consumption in simulation and experiment. Proposed controller based on the combination of ℋ2 and ℋ∞ controllers in the inner control loop shows the robustness of the proposed methodology. In the outer loop to have a good tracking performance, an integrated MPC is used to handle delay in system dynamics. Also, the main idea for dealing with uncertainties is using integral and derivative of platform attitude. In the proposed platform, the ℋ∞ controller is compared with ℋ∞/ℋ2 controller in KNTU laboratory in theory and experiment. Results of experimental set up shows the same reaction of two controllers against disturbance and uncertainties in delayed system.

In this paper, we describe our implementation of an interior point algorithm for large scale systems. First we identify system with small and medium methods convex optimization, then we use interior point method for identification. Finally we offer an interior point method that uses nonlinear cost function and see that we achieve a good trade-off between error and CPU time. Actually, in this paper, we are looking for a method that can identify large scale systems with low model order, error and CPU time of solution of simulation. Previous articles didn’t check the order of the computed model, and the relationship between the error and CPU time. We assume that the model of our simulation is ARMA. We are going to identify a large scale system and compute the error and CPU time and compare the relationships. Examined data in this paper is related to cutaneous potential recordings of a pregnant woman. These data are pendulous and have a large standard deviation; therefore, it can’t be fitted with ordinary curve fittings, so we use the smoothing spline for computing the order of the model. Finally, we checked the influence of the number of data on error and CPU time and order of model

The share of DC-based Renewable Energy Resources (RERs) and electricity storage systems are increasing due to developments of smart grid technologies. Moreover, the share of DC-based load has rapid growth due to significant developments of power electronic technologies. Therefore, a more flexible power system is required for efficient integration of emerging loads and generators. In this paper, hybrid AC-DC Local Network (LN) is incorporated as an appropriate topology versus conventional AC LN to reinforce the integration of RERs and Plug-in Hybrid Electric Vehicles (PHEVs). A mixed integer linear model is developed for operation of both hybrid AC-DC LN and conventional AC LN topologies considering high penetration of RERs and PHEVs. This operation model is solved by GAMS optimization software to minimize the operation cost and find the optimum inter-resource scheduling in the day-ahead market. Moreover, investment analysis and reliability assessment are carried out for the mentioned LNs. Numerical study is conducted to evaluate the ability of both topologies for better utilizing the opportunities of integration