Improving Output Performance of a Z-Source Sparse[taliem.ir]

Improving Output Performance of a Z-Source Sparse Matrix Converter Under Unbalanced Input-Voltage Conditions

In this paper, we present a novel Z-source sparse matrix converter (ZSMC) and a compensation method based on a fuzzy logic controller to compensate unbalanced input voltages. The ZSMC is developed based on the structure of an SMC to reduce the number of unipolar power semiconductor switches and employs a Z-source network to overcome the inherent limitation of the low voltage transfer ratio of conventional matrix converters. Although the ZSMC is a two-stage converter, it directly connects between a source and a load through a Z-source network, which is designed to have smaller passive components as the only purpose is voltage boosting. Therefore, the output of the ZSMC is directly affected by disturbances of the input-voltage source. The operational principle of the ZSMC is described and its modulation strategy is explained. Simulation and experimental results are shown to verify the feasibility of the ZSMC and its compensation method.
A Novel and Fundamental Approach towards Field[taliem.ir]

A Novel and Fundamental Approach towards Field and Damper Circuit Parameter Determination of Synchronous Machine

In this era of advanced computing where complex algorithms and expensive approaches are used to determine the machine parameters of a synchronous machine, this paper proposes a novel, economical and yet fundamental approach towards estimation of the d- and q-axis field and damper circuit parameters of a low/medium power wound-field synchronous machine. The proposed novel methodology employs fundamental voltage, current, flux linkage relationships of the 3-phase wound-field synchronous machine in a-b-c reference frame theory. Firstly, the proposed methodology has been explained in detail using analytical equations and then employed to determine the aforementioned parameters of a small laboratory synchronous machine. Other equivalent circuit parameters have been determined using conventional tests. Further validation of the proposed methodology was performed using two other larger machines with different nameplate ratings. Moreover, the aforementioned parameters of the larger machines were also experimentally determined using IEEE standard tests. Finally, a comparison of the results obtained employing the conventional and the proposed methodologies were performed and the proposed methodology has been established to be valid as the results are in close agreement.
Design and Simulation of UPQC to Improve Power Quality and Transfer Power of[taliem.ir]

Design and Simulation of UPQC to Improve Power Quality and Transfer Power of photovoltaic array to grid

In this paper the design of combined operation of UPQC and PV array is proposed. The proposed system is composed of series and shunt inverters, PV array connected to DC link by boost converter which is able to compensate the voltage sag and swell and voltage interruption, harmonics and reactive power in both islanding and interconnected modes. The proposed system is able to inject the active power to grid in addition to its ability in improvement of power quality in point of common coupling. Also it can provide a part of sensitive load power during voltage interruption. The results of simulation in PSCAD/EMTDC software show that the mentioned system operates correctly.
Modified Dynamic Phasor Estimation Algorithm for[taliem.ir]

Modified Dynamic Phasor Estimation Algorithm for the Transient Signals of Distributed Generators

In this paper, a modified dynamic phasor estimation method for protection relays is proposed to calculate the dynamic phasor of a fundamental frequency component with time-variant amplitude. The fault current is assumed to be the combination of a decaying dc offset, a decaying fundamental frequency component and harmonics with constant amplitude. The exponential functions of the decaying dc offset and fundament frequency component are replaced by Taylor series. Then, the LS (Least Square) technique is used to estimate the magnitudes and the time constants of decaying components. The performance of the algorithm is evaluated by using computer-simulated signals based on simple equations and fault current signals collected from DFIG wind farm model in MATLAB Simulink. The test results indicate that the proposed algorithm can accurately estimate the decaying amplitude and the time constant of the fundamental frequency component.
Algebraic observer design for a class of uniformly-observable nonlinear[taliem.ir]

Algebraic observer design for a class of uniformly-observable nonlinear systems: Application to 2-link robotic manipulator

We propose a globally convergent observer for three-state nonlinear systems verifying the uniform complete observability condition. By constructing a time-varying differentiator, we are then able to reproduce the first and the second derivatives of the system output without imposing the boundedness of the states or the output. By exploiting the algebraic observability of the system, we show that the unmeasured states can be reproduced as nonlinear outputs of the time-varying differentiator. This new technique has several advantages over classical observer design methodologies that are basically related to the form of the system nonlinearities. It will be shown that the complete uniform observability implies the existence of globally convergent observer without major restriction on the system nonlinearities. Illustrative example is provided to demonstrates the efficiency of the proposed design.
Research on energy management and its control[taliem.ir]

Research on energy management and its control strategies of microgrid

In this paper, the microgrid which is composed of photovoltaic cells, microturbine, storage device and load is researched. On the basis of analysis of the typical structure of microgrid and the operation modes of every microsource, the program of energy management is presented and designed, and its control strategies are researched under the condition of both grid-connected mode and islanding mode. Several algorithmic examples have been studied through simulation, and the simulation results verify the correctness of the energy management’s control strategies. The research results indicate that it can ensure the high efficiency and stability operation of microgrid through the coordinated control of energy management.
Congestion management using demand response and FACTS devices[taliem.ir]

Congestion management using demand response and FACTS devices

An approach is proposed for transmission lines congestion management in a restructured market environment using a combination of demand response (DR) and flexible alternating current transmission system (FACTS) devices. To achieve this aim, a two-step market clearing procedure is formulated. In the first step, generation companies bid to the market for maximizing their profit, and the ISO clears the market based on social welfare maximization. Network constraints including those related to congestion management are represented in the second step of the market-clearing procedure. The paper develops, using mixed integer optimization technique, a re-dispatch formulation for the second step in which demand responses and FACTS device controllers are optimally coordinated with conventional generators.
Characterization for Novel Non-traditional CMOS[taliem.ir]

تاریخچه و اهمیت پایگاه داده های غیررابطه ای NOSQL

چندسالی است که موضوع پایگاه دادهNOSQL مطرح شده است و تصوری که وجود دارد، جدید بودن این نوع پایگاه داده است و اینکه این نوع پایگاه داده را شرکت­های بزرگی مانند گوگل و فیس­بوک و آمازون و غیره ایجاد کرده­اند و بنیان­گذاران این نوع پایگاه داده این شرکت­ها می­باشند که این موضوع را بررسی خوهیم کرد.
آنالیز کارآیی سیستم مخابرات نوري با استفاده از فیبر با شبکه براگ و پیشگویی رفتار سیستم با[taliem.ir]

آنالیز کارآیی سیستم مخابرات نوري با استفاده از فیبر با شبکه براگ و پیشگویی رفتار سیستم با استفاده از شبکه عصبی

در این مقاله شبیه سازي سیستم انتقال نوري مورد بررسی قرار گرفته است. براي رسیدن به کارآیی بالا در سیستم هاي مخابرات نوري، باید پاشندگی گونه به اي محدود شود. همچنین از فیبر شبکه براگ به عنوان عنصر مهم جهت جبران پاشندگی در سیستم هاي مخابرات نوري استفاده میشود. شبیه سازي سیستم بر اساس پارامترهاي متفاوت با استفاده از شبیه ساز OptiSystemانجام میشود. سیگنال بدون بازگشت به صفر با نرخ 20Gb/sدر طول یک فیبر تک مد استاندارد به طول 50Km منتقل میشود. با شبیه سازي مدل سیستم مخابراتی و استفاده از تغییرات پارامتري سیستم که شامل توان ورودي، طول کابل نوري و طول فیبر شبکه براگ میباشد میتوان کارآیی سیستم را افزایش داد. مقایسه دیاگرام چشمی به ازاي فواصل مختلف فیبر و طول فیبر شبکه براگ بهبود کارآیی لینک را نشان میدهد. در این میان از شبکه عصبی براي پیشگویی و بهینه سازي رفتار سیستم استفاده شده است. مقایسه نتایج با استفاده از خروجی شبکه عصبی و شبیه سازOptiSystem توافق خوبی را نشان میدهد.
Characterization for Novel Non-traditional CMOS[taliem.ir]

Characterization for Novel Non-traditional CMOS Inverter Composed of a Junctionless NMOSFET and a Gated N+-N–P Transistor

We present a non-traditional CMOS inverter composed a junctionless (JL) NMOSFET and an N+-N--P transistor which with simple process and high integration density in this paper. In the non-traditional CMOS inverter the JL NMOSFET serves as driver and the �-N--P transistor serves as load, respectively. Based on the measurement date of the N+-N--P transistor published, we draw the load line of the non-traditional CMOS inverter and we found out that the �­ N--P transistor can be used in the COMS circuit to advance the issues of the conventional CMOS today. Besides, the area reduced more than 46.1 % are also be achieved.