Sharif Digital Repository

Transmission lines congestion has recently been a vital challenge in power systems operation due to the intermittent outputs of renewable energy sources (RES). Therefore, an efficient transmission congestion management (TCM) method should be defined to deal with the congestion issue. This paper aims to propose a simultaneous linearized two-stage TEP-BESS co-planning optimization model to relieve transmission lines congestion. In doing so, a novel TCM structure is suggested in a pool-based deregulated data-driven optimal power flows (D-OPF) by the computationally effective min-max regret method to consider future scenarios of generating units and demanded loads. To improve the efficiency of... 

This paper proposes a comprehensive analytic method for applying various optimal remedial actions to improve critical electromechanical modes damping without jeopardizing damping of non-critical modes and violating security constraints of power system. Generators and reactive power sources redisptach, demand side management and the generators voltage reference tuning are remedial actions that are considered here. Dynamic equations of the flux-decay dynamic model of generators, standard dynamic models of excitation system and power system stabilizer and algebraic equations of active and reactive powers balance are formulated in the quadratic eigenvalue problem framework. With simultaneous use... 

This paper introduces a new concept that we call smart transmission expansion planning (TEP) based on unconventional high surge impedance Loading (HSIL) line designs that will revolutionize power delivery. To date, these two areas (TEP and transmission line design) have been conducted separately. For TEP, planners use the electrical parameters of a few standard conventional line designs to study planning scenarios, and then, the final candidate line is constructed. In such a sequence, cost-effective scenarios often do not meet the technical criteria of load flow. This paper will demonstrate that this sequence can be overturned; namely, a transmission expansion planner can get optimal line... 

This article presents a novel dual-band transmission line (TL), consisting of a multibranch stub, which can provide equal unwrapped phases at two different frequencies. The frequency ratio can be close to one without any significant degradation in the device performance. Besides, the bandwidth of the proposed line can be manipulated at both frequencies by adjusting the design parameters. The behavior of the structure over the frequency bands is investigated theoretically, and the design procedure and relations are derived. The simulation and measurement results of a quarter-wavelength open-ended stub and a branch-line coupler (BLC) are presented and compared to verify the performance of the... 

A practical coplanar Josephson junction left-handed transmission line based on a step-edge junction technique is proposed in high-temperature superconductor technology and analyzed by electromagnetic simulations. The layout is designed for monolayer Yttrium Barium Copper Oxide thin film fabrication process. The propagation stopbands are tunable by controlling bias currents of Josephson junction arrays acting as parallel inductors for unit cells of the transmission line. Unlike the reported designs, each unit cell of our left-handed transmission line is independently biasable due to dc isolation of the unit cells along the transmission line. Being individually biasable is practically... 

Here, using the probabilistic evaluation based on the Monte Carlo method, back-flashover rate and shielding failure flashover rate of 230 kV overhead transmission lines in the western regions of Iran are evaluated. To such an aim, first, the number of thunderstorm days per year is collected from the reported weather information in order to determine the ground flash density. Then, using MRU-200 equipment, the tower-footing resistance of several towers is measured. Matlab® software is used in order to produce lightning surges considering its probabilistic nature and randomly distribution on the ground to evaluate striking distance based on the geometric model. Then, calculated parameters are... 

Electric vehicles (EVs) usage is becoming ubiquitous nowadays. Widespread integration of electric vehicles into electric energy distribution systems (EEDSs) has a twofold impact: (1) It may impose a burden on EEDSs when EVs are charging, (2) EVs could discharge their battery capacity using V2G technology when required. To mitigate adverse effects of massive integration of EVs in EEDSs, EVs could be used as mobile energy storage devices (MESDs) to transfer electric energy throughout EEDSs using a proper charging/discharging scheme. In this paper, a mixed integer linear programming (MILP) model is proposed to control charging and discharging of EVs to improve EEDS performance. EVs are modeled... 

This paper proposes a control strategy to improve the superimposed droop frequency control scheme in DC microgrids. Conventional droop-based schemes for DC microgrids control suffer from issues such as inaccurate power sharing among the sources, voltage control with insufficient quality, and adverse effect of the line resistance on the droop characteristic. To overcome these challenges, the superimposed droop frequency method has been introduced. However, the stable operation in terms of the load variations and improper voltage quality are still the challenges with this prior-art method due to the injected AC voltages. In this paper, a method is proposed to solve the stability problem and... 

The local electric field distorsion induced by a dielectric particle leads to particle–particle interactions and assembly which is very interesting for their useful applications on microfluidic devices. Particles behavior becomes more complicated if several particles interact at the same time. This paper presents a comprehensive numerical analysis of the assembly and particle–particle interactions for two similar and dissimilar dielectric particles immersed in a dielectric fluid using the immersed interface method based on two-dimensional direct-current dielectrophoresis. The immersed interface method is a finite-difference (or finite element) based numerical method which its key advantage... 

This paper finds near equilibrium prices for electricity markets with non-convexities due to binary variables, in order to reduce the market participants’ opportunity costs, such as generators’ unrecovered costs. The opportunity cost is defined as the difference between the profit when the instructions of the market operator are followed and when the market participants can freely make their own decisions based on the market prices. We use the minimum complementarity approximation to the minimum total opportunity cost model, from previous research, with tests on a much more realistic unit commitment model than in previous research, including features such as reserve requirements, ramping... 

This paper presents analysis of electric field distribution and optimization of C-type corona rings for 400 kV V-insulator strings composed of ceramic insulator units which are the most common configuration of overhead transmission lines. These strings are equipped with corona rings to enhance the insulation performance regarding to the effect of these rings on the insulation function and potential and electric field distribution. 3D field simulations are performed for the C-type of corona rings with different dimensions by software based on FEM analysis  

Nonlinear transmission lines (NLTLs) are passive networks with the capability of modulating baseband pulses. These networks are used for generating RF pulses at high-power levels. NLTLs have a unique performance in high-power RF pulse generation among all the generators based on the solid-state technology. A high-power rectangular pulse is injected to the line, gradually evolved into an oscillatory pulse while propagating through the network, and finally, in the form of a high-power RF pulse, is delivered to the load. Properly terminating an NLTL, in order to transfer the maximum available RF power to the load, is an important problem. In this paper, an accurate analysis is presented, which... 

In this brief, a design technique for tapered distributed low-noise amplifiers (LNAs) is presented. A circuit model is developed for gain and noise analysis of a nonuniform distributed amplifier (DA). It is shown that by optimal tapering of gate and drain transmission lines and transistors, the tapered distributed LNA can provide lower broadband average noise figure (NF) compared to a uniform DA. A proof-of-concept integrated circuit is implemented using a 0.1-μm GaAs pHEMT process. The amplifier provides average gain of 15.2 dB and 3-dB bandwidth of 43.3 GHz. The average NF of 2.3 dB and minimum NF of 2.0 dB are achieved over 2-40 GHz. The chip consumes 55 mA current from a 2-V supply. ©... 

Nonlinear transmission lines (NLTLs) are one of the most prominent solid-state sources of high-power RF pulses. However, there is no integrated mathematical basis, which predicts adequately the generated waveforms on an NLTL and those delivered to the load. This analysis is required for designing and optimizing these transmission lines. Most works in this area are related to experimental studies and results. In this paper, we have developed a theoretical basis, which predicts all the required characteristics of the generated RF pulses on a lossy NLTL. The RF amplitude, the maximum voltage, and the central frequency of the generated pulses at each node of an NLTL are formulated. All the... 

A new resonance phenomenon is demonstrated in waveguide cavities, which simultaneously uses two orthogonal modes (polarizations). This resonance is formed by bouncing waves with similar handedness, between two simple anisotropic metasurfaces having a relative rotation angle. The rotated anisotropic metasurfaces can cross couple the waves from one polarization to the other at the cavity end. The field profile of the resonant mode does not exhibit nodes and antinodes, thus the resonant frequency is not solely determined by the cavity length, unlike common resonators. The resonance condition is theoretically demonstrated from both field and transmission line perspectives, and is validated by... 

The modal analysis of a lossy coupled plasmonic waveguide consisting of two graphene sheets sandwiched among three SiO 2 layers is presented. This analysis extracts even and odd complex propagation constants in addition to even and odd characteristic impedances at various Fermi levels. It is shown that the first even mode is lossless in theory, but other modes are very lossy. Taking into account the losses, first, the transmission line (RLCG) model, including self and mutual elements, is constructed for various Fermi levels and frequencies. Then, the length of a lossy plasmonic directional coupler based on the coupled plasmonic waveguide is designed for a variety of Fermi levels. The... 

Properly terminating a transmission line, in order to transfer the maximum available power to the load, is an important issue. The problem, fully analyzed in linear lines, is still considered as a persisting problem in the area of nonlinear transmission lines (NLTLs). In this paper, an accurate analysis is presented which gives a closed-form formula for the matching efficiency of the NLTLs. Using this analysis, optimal resistive terminating load for the NLTLs was extracted. These results will considerably ease the design of all kinds of the NLTL-based systems, such as high-frequency oscillators and ultrashort pulse generators. This consistent analysis also gives the reflection coefficient... 

Line generators were attractive structures for high-power radio frequency (RF) pulse generation for two decades. Due to some disadvantages, there has been little attention to this type of generator for a relatively long time. In this paper, a nonuniform line generator is used which resolves some of the main shortcomings of conventional line generators. The considered generator can generate RF pulses at higher frequencies with considerably higher repetition rates. Furthermore, the implementation of nonuniform line generators is significantly easier than that of their conventional counterparts. Measurement results for three nonuniform line generators are presented. The possibility of... 

A dual-band neutralization technique based on the transformer feedback between the drain and the gate of a transistor is presented. The drain and gate bias lines of the transistor are realized as multiorder LC networks. Transformer coupling between the inductors of the two networks can be used to concurrently neutralize the gate-drain capacitance of the transistor at multiple frequencies. Moreover, these frequencies can be placed close together to achieve wideband neutralization. A proof-of-concept dual-band 27/33-GHz amplifier is designed and implemented in a 0.1-μm GaAs pseudomorphic high-electron mobility transistor process. The maximum gain of the transistor at the two frequency bands is... 

Minimization of operating costs is one of the most important objectives of power system operators. To achieve this goal, several optimization problems such as unit commitment and optimal power flow have been introduced. Historically, in these problems, the transmission network has been considered as a static system, i.e., the ability of transmission lines switching is not modeled. On the other hand, it has been shown that transmission line switching can significantly reduce operating costs by the means of topology modification. However, considering this capability, a large number of binary variables are introduced in the objective function, and as a consequence, the computation time will be...