نشریه مهندسی برق و مهندسی کامپیوتر ایران
سال هجدهم شماره 2 (پیاپی 55، تابستان 1399)

Gas fueled power stations are considerably effective in power system operation during peak hours due to their high up and down ramping rates. By increasingly penetration of gas fueled power stations in power systems and development of new technologies such as power-to-gas (ptg) units, coordinated scheduling of both electricity and natural gas (NG) networks has attracted researchers’ attention of both systems. The NG volume generated by ptg units are stored in storages to directly supply the NG demands, or to sell in NG markets. If necessary, the stored NG volumes are converted into electricity, again; this method is a suitable replacement for batteries and storages in electricity network in long-term. In this paper, a mixed integer linear programming (MILP) model is proposed for coordinated scheduling of electricity and NG networks considering ptg units. A test network integrating modified 24-bus IEEE electricity network and Belgium gas network including nine power stations (three of them are gas fueled), three vehicle to grid (v2g) stations, and three ptg stations is studied to evaluate the effectiveness of the proposed model. Results of simulations demonstrate the effectiveness of ptg units in handling the uncertainties of v2g stations charging and discharging.

One of the main tests of power circuit breaker is to evaluate their breaking capability. Direct test requires a very high power source but By using the synthetic method and supplying current and voltage from two separate sources, we will have a significant reduction in the required power.This paper presents the design, development, and fabrication of a synthetic circuit for testing vacuum circuit breaker by using distribution network as current circuit. The development and construction of this equipment has made it possible to perform short circuit breaking tests on VCB in accordance with international standards. Laboratory measurements show that the set is in good conformity with the design and can be used to perform the standard breaking test on the medium voltage VCB.

Nowadays, in the electric power industry, optimal and effective design and operation of gas and electricity networks are tightly related together. In cooperative operation of the electricity and gas industry, one of the main goals is the coordination of the electricity and gas network to achieve minimum operation cost. In this research, the centralized operation of electricity and gas networks is modeled on a real case study in Khorasan province. This modeling is from the point of view of a central coordinator, seeks to minimize the total operation cost of electricity and gas networks while taking into account the technical constraints. Decomposition methods based on ATC and ADMM methods is accomplished to preserve the privacy of gas and electricity networks. Gas consumption in gas and electricity networks is compared using different methods including ADMM, ATC and centralized methods wherein fuel cost is supposed to be $ 3.5 per million BTUs. Different load and fuel scenarios have also been investigated.

This paper proposes a 5/6 switch reluctance motor with multipart rotor. Operation improvement of SRM by modification of rotor structure is the primary objective. Proposed rotor structure modification causes lower torque ripple and increase of motor efficiency. Proposed SRM consists of two stator poles, primary poles and auxiliary poles. Utilization of auxiliary poles causes a shorter flux path and eliminates some areas that reverse flux happened from main flux path. Therefore, iron loss decreases. In this regard, various topologies of rotor slot analyzed by evaluating motor performance and most optimized topology considered. Simulations results conducted using FEM confirms the robustness of proposed topology.

As technology nodes shrink below 90 nm, high static power consumption has become one of the biggest problems of CMOS based circuits due to the exponential leakage current of transistors. Spintronic devices such as magnetic tunnel junction (MTJ) due to their fascinating features such as low static power consumption, non-volatility, high endurance, compatibility with CMOS transistors and high-density fabrication are one of the promising candidate for designing hybrid MTJ/CMOS circuits and overcoming high static power consumption of CMOS based circuits. In this paper, a fully nonvolatile and low power hybrid MTJ/CMOS full-adder circuit for Realization of Process in Memory is proposed. The simulation results show that all the proposed circuit is at least 50% faster than all previous counterparts, the power output delay is 39% lower than the previous design, and does not impose high hardware overhead.

Due to development of sensitive loads like data centers, the use of DC microgrids has expanded. Line-to-ground fault is the most common type of fault in this type of microgrids, causing various damage to the DC grid. One of the most important challenges in using DC microgrid is the lack of effective protection against this fault. In this paper, using local measurements such as the voltage and current at the beginning of each line and by evaluating the variation in their instantaneous power, a novel protective scheme that is not based on any communication line is proposed. The proposed protection scheme has a good accuracy and speed, and it is able to protect the DC miccrogrid from line-to-ground faults. The accuracy and precision of the proposed protective method in various situations have been tested.

In this paper, design and simulation of a new micro-displacement sensor based on photonic crystal fixed and movable segments is presented. It has been shown that using negative refraction photonic crystal in the fixed segment, the transmitted power is concentrated on the entrance of the movable segment, and the sensor specifications are improved. Based on the FDTD simulation results, the sensitivity, the operational displacement range and the regression coefficient of the proposed sensor are 1.1 (a-1), 0.35a and 0.99848, respectively. The simulation results show that the proposed sensor has a good performance and could well be used in micro-displacement measuring systems.

Photonic crystals are structures that can restrict light beams within the range of photonic band gap. In this paper, a design of a bio-sensor based on a photon crystal has been presented. This sensor consists of two adjacent circular nano-rings which consequently causes the waveguides and the resonating nano-ring to merge. Few dielectric bars have been embedded in sensor design. These bars are located in a watery medium. Also, circular resonating rings are used between the input and output waveguides. A closed-end condition is used for input and output paths, in order to enhance the optical restrictions and ameliorate the performance of coupling of waveguides and the resonating nano-ring. The simulation results show that the designed bio-sensor has high output transmission power and high quality factor, and also when a biological molecule is connected to it, a well formed resonant wavelength displacement will be obtained.