Search

Nowadays, energy supplied by the reliable manner is one of the important challenges of the distribution company in the radial distribution system. Therefore, this paper considers these challenges by the optimal DG placement to minimize power losses with considering the analysis related to the reliability and voltage profile. In this paper, exchange market algorithm (EMA) is used as a powerful tool to solve the optimization problem. In order to extract the global optimum point, EMA uses two searching operators and two absorbent operators based on the generation of random numbers. To evaluate the goals of this paper, EMA is successfully implemented on 10, 33, and 69 bus IEEE test systems. Simulation results have illustrated that power losses are reduced by the optimal DG placement and size. Finally, the analysis of obtained results has shown the system's reliability; voltage profile can be improved if the DGs are allocated optimally in the radial network. [ABSTRACT FROM AUTHOR]

This paper presents a simulation of the dynamic voltage stability in power system. In application of modern power system, dynamic assessment of voltage stability is known as basic concept. In order to study dynamic voltage stability in a power system, different dynamic boundaries are defined such as, Hopf bifurcation (HB) boundary. HB point is an oscillatory boundary in power system. For recognition of the bifurcations, it is unavoidable to study the eigenvalues of power system. In spite of this, determination of these eigenvalues needs to dynamic Jacobian matrix of power system and modal analysis that is very time consuming and complex in large systems. Also, different industrial loads (static and dynamic) e.g. induction motors can effect on dynamic voltage stability boundaries. In this paper, we proposed a solution method based on analyzing the eigenvalues of reduced Jacobian matrix and time domain simulation for assessment of dynamic voltage stability. In addition, effects of industrial electrical loads on the small disturbance voltage stability are evaluated by the proposed method. To show the effectiveness of the proposed solution method, it is tested on IEEE 14 bus and New England test systems. [ABSTRACT FROM AUTHOR]

DC microgrids have gained extensive attention in the recent years. In the islanded mode of operation power sharing between sources is required. The power sharing usually is provided by employing P-V droop characteristics while the voltage local property results in power sharing error. In this paper two decentralized approaches for resolving power sharing error are studied and compared. In the first approach, sources employ proper virtual resistance. In second approach, droop characteristics are realized in the Point of Common Coupling (PCC). It is shown that by using second approach, the voltage drop is reduced and equally the voltage quality is improved. It is discussed that the reason is bypassing the voltage drop associated with the sources output resistance in the second approach. Time domain simulations of a test DC microgrid are provided to verify the results. [ABSTRACT FROM AUTHOR]

Dual input step-up Switched Capacitor Inductor (SCI) converters have been investigated in this paper. At first, the structure of this converter is reviewed and analyzed carefully. It has shown that besides capacitor and inductor, a small resonant inductor is also used in order to limit the current peak, which is caused by switched capacitor. Therefore, efficiency has been improved. In the proposed solution, fuzzy control method is used for controlling and switching the circuit. Simulation results have revealed that by using this method; the output waveforms are according to idealized ones while achieving a high voltage gained. In addition, by using such method, the output voltage ripple is significantly decreased. [ABSTRACT FROM AUTHOR]

The purpose of this paper is to design an adaptive neuro-fuzzy controller to control the speed of the BLDC motor. This paper throws overall view of the performance of fuzzy PID controller and compares with fuzzy - adaptive neural controller. Taking suitable characteristics in PID controller is difficult, but fuzzy is has the ability to take appropriate control parameters and calculations easier. An adaptive neuro fuzzy control system has the advantages of both types of fuzzy control system and neuro system. This paper examines the BLDC motor speed control based on adaptive neuro - fuzzy, first by simulating fuzzy PID controller and then designing controller adaptive neuro - fuzzy using ANFIS toolbox for the motor. The characteristics of speed, torque, current and voltage in the three controllers finally are compared and it was concluded that the characteristic of the controller adaptive neuro - fuzzy (ANFIS) is better than the other two controllers. [ABSTRACT FROM AUTHOR]

This paper utilizes the improved group search optimization algorithm for optimal reactive power dispatch (ORPD). The ORPD problem is a non-linear, non-convex optimization problem which has various decision variables such as compensation capacitor proportions, voltage of generators and the tap position of tap changing transformers. In this paper the multi-objective ORPD considering loss, voltage deviation and the security index is studied. Due to complicating objectives and also physical and operating constraints, an efficient optimization algorithm is needed. This paper solves the mentioned problem using the group search optimization algorithm (GSO). GSO is one of the novel presented optimization algorithms based on group living and especially searching behavior of animals. In order to improve the algorithm efficiencies, the improved group search optimization algorithm (IGSO) is used. Accordingly, the algorithm would obtain better results due to its ability to find better solutions. Moreover, the penalty factor approach is used in order to solve the multi-objective case. [ABSTRACT FROM AUTHOR]

Among various types of Distributed Generations, Microturbine (MT) Generation (MTG) systems are known as highly reliable and efficient sources. The MT must support demands in different conditions, which requires its proper control. In this paper, hybrid operation of the MTG is considered which is initially isolated from utility grid, and after that it is connected to the distribution network. A robust control method is used for stand-alone mode and a novel power-voltage control strategy is applied to grid-tied inverter. In stand-alone mode, the voltage, frequency and current are used as control parameters instead of traditional voltage-frequency control. In grid-connected novel controller, the inner voltage loop is substituted with the current loop, so it is based on powers and voltage. The simulations are performed by MATLAB/Simulink, with the results indicating proper power sharing as well as load-following performance with the minimum level of distortion. The proposed strategy can be used in hybrid operations of the MTG. [ABSTRACT FROM AUTHOR]

In this paper, a novel circuit for memristor based IIR filter implementation is presented. In this research for increasing the input voltage range in sampling the analog signal, complementary switches were used instead of single-transistor switches. In addition, to increase the filter accuracy, a delayed circuit with the ability to implement high-order filters is presented. In this work, coefficients of the IIR filter were implemented by memristor; using such component could provide in-system reconfigurability. The memristor could decline receiving negative values, where IIR filter coefficients have negative values. In this research a new method for generating negative numbers as filter coefficients is presented. During running an advanced search algorithm, the memristor values were set at six, seven, and eight bits of resolution; these values cause memristors have the lowest error rate in generating coefficients. All circuits were simulated by Cadence tools on TSMC 0.18 micrometer technology platform with 1.8 volt power supply. In simulation results, outputs of low/high-pass filters along with the error rate of coefficients calculated and compared to actual coefficients. [ABSTRACT FROM AUTHOR]

This paper presents a Direct Torque Control (DTC) strategy for the Permanent Magnets Synchronous Machine (PMSM). The principle relies on a Space Vector Modulation (SVM) technique that uses hysteresis comparators for the determination of the voltage module and angle, the proposed control method is simple to implement. It allows reducing the fluctuations level of the torque and the flux in low speed conditions. Contrary to the classical DTC technique, the proposed approach is able to handle and to control the switching frequency even for driving the motor with a low speed as a reference. Simulations results were obtained and allowed demonstrating better performance of this command especially in the behavior of the couple and the flux. [ABSTRACT FROM AUTHOR]

Under-voltage load shedding is an important measurement to maintain the voltage stability in power systems. In this paper, a new combined index is proposed for under-voltage load shedding. The proposed index is weighted combination of importance, sensitivity and value of loads. This is of paramount importance, since three vital factors such as importance of load, sensitivity of minimum eigenvalue of load flow Jacobian respect to load and the amount of loads are considered for optimal under-voltage load shedding. The algorithm accounts constraints not only in present operating condition but also for predicted next interval load. The proposed method is applied on IEEE 14-bus test system. This paper formulates the optimal under-voltage load shedding problem for power system as a Nonlinear Programming (NLP), and it solves the proposed problem using Generalized Algebraic Modeling Systems (GAMS) software package with CONOPT solver. Results have been compared with those researches based on sensitivity analysis. The results showed effectiveness of proposed index. This proposed index can be used in selecting candidate buses in different power system problems. [ABSTRACT FROM AUTHOR]

In this paper, we applied the Data Envelopment Analysis (DEA) ranking method to have efficient placement of Distributed Generation (DG) in distribution network. In this regard first an analytical method to find the optimal size of DG in the network is used to reach the lowest possible losses. In this paper, benchmarks such as improvement of voltage profile, reducing energy not supplied value (as an index of reliability), reducing environmental pollution, and values related to the purchase and installation costs of DG equipment in each busses for selecting the appropriate DG location are considered, in addition to the network loss reduction. This method has been used because the loss reduction of whole the network will not be a complete criteria for selecting the best location to install DG, The necessarily node which has the highest reduction in power losses cannot be considered suitable node for the installation of DG. Therefore we used DEA to determine the most effective location for DG placement. The proposed method is implementation over the network of 33 buses and the results are presented. GAMS software is used for the simulation results extraction. [ABSTRACT FROM AUTHOR]

Hybrid Energy Storage System (HESS) has been implemented for better energy efficiency to Hybrid/Electric Vehicles (HEV/EV), in that the main source is Battery and UltraCapacitor (UC) is the auxiliary source. The battery is connected to DC Bus through Boost Converter and UltraCapacitor has been connected through Buck-Boost Converter. Battery and UltraCapacitor voltages levels are maintained less than the DC bus voltage. The main aim of this paper is to design an intelligent controller for a smooth transition between the sources in the Hybrid Energy Storage System. Math Function Based (MFB) Controller has been modelled and implemented to an electric motor for Electric/Hybrid Electric Vehicle Application. The MFB controller has to work based on the Speed of the motor and this controller makes the closed loop operation of the overall system with smooth operation between the energy sources. Proportional Integral (PI) controller was used here to maintain the constant voltage profile for various loads at the terminals of the electric motor. Combination of PI and MFB controllers has given closed loop operation of the entire model with smooth switching between the sources. The total circuit has been simulated in MATLAB/Simulink and obtained the satisfactory results, which are discussed in the results section. [ABSTRACT FROM AUTHOR]

This paper presents the simulation of the process of LDMOS transistor manufacturing by using Silvaco software and by relying on the ability of calculating the basic parameters of transistor dependencies, focusing on the optimization of the manufacturing process in order to increase the current of work. By using this simulation and reviewing each parameter, we can achieve the optimized manufacturing process by focusing each basic parameter and by paying attention to its required application. In order to design, we first define the construction procedures and the necessary processes using the Athena simulator, and then we use the Atlas device simulator to acquire electrical parameters. Simulation results show that by selecting the optimal parameters of the manufacturing process such as gate oxide thickness, channel length, and doping in channel, we can increase current of the LDMOS transistor [ABSTRACT FROM AUTHOR]

Design of a very compact two stage amplifier is proposed by merging passive frequency compensation with a feed forward compensation technique, which achieves significant improvement in gain-bandwidth product (GBW), slew rate and phase margin with lower supply voltage requirement. The mathematical analysis given in this paper justify that the proposed technique offers the advantage of locating poles and zeros at higher frequencies than with the conventional method . The workability of the proposed amplifier has been verified by using Mentor Graphics Eldo simulation tool with TSMC CMOS 0.18 μm process parameters. The simulated results show a GBW of 150 MHz and average slew rate of 98 V/μs with a power consumption of 3.2 mW. [ABSTRACT FROM AUTHOR]

In this paper a low-noise amplifier with 0.6V supply voltage, low power consumption, and improved linearity at 5GHz is introduced in 0.18 μm CMOS technology. By using a feed-forward structure and a multi-gated configuration in the proposed circuit, linearity of the circuit is significantly improved, while only 122 μW more power is consumed compared to conventional folded cascode structure, and the other circuit parameters are similar. In addition, the Volterra series is used for nonlinear analysis and to evaluate the linearity improvement of the proposed circuit. There is also a noteworthy superiority over compared published works in the figure of merit. The suggested low-noise amplifier (LNA) at 1.28mW DC power consumption provides 9.6dB gain and a noise figure of 3.24dB. It is achieved whilst the third order interception point has been improved by 10dB and equals 0.0dBm. In the operating frequency the circuit displays satisfactory input and output impedance matching. Finally, throughout the whole circuit bandwidth input and output isolation is below −27dB. [ABSTRACT FROM AUTHOR]

In viewpoint of technology-driven custom power apparatus, dynamic voltage restorer (DVR) is recognized as a most prominent device which can be implemented to compensate the voltage sag. On the other hand, this device has been customarily used in power distribution system to protect sensitive loads from sudden voltage sag. Owing to the restriction of energy storage in DVR's capacitors, it is essential that the active power injection by DVR to be reduced. As a consequence, this energy-saving strategy leads to the injecting the larger voltage magnitude and reactive power, shifting the phase, and cluttering the voltage wave shape. Meantime, this strategy is very sensitive respect to variation in load's power factor, so that the compensating operation will not be properly performed. In this regard, this paper suggests a flexible controller based on minimum active power strategy in order to perfectly correct the voltage sag notwithstanding variation in load's power factor. Likewise, the under-study DVR has been structured according to the cascaded H-bridge multilevel inverter topology. [ABSTRACT FROM AUTHOR]

In this paper, the influence on the voltage compensation type, active superconducting fault current limiter (ASFCL) is investigated under symmetrical and asymmetrical fault conditions. ASFCL is consisting of three air-core superconducting transformers and a three-phase voltage source converter. In the normal (no fault) state, the flux in air core is compensated to zero, so the ASFCL has no influence on the main circuit. In the case of short circuit, by controlling the amplitude and phase angle of the second winding's current, the limiting impedance which is in series with the AC main circuit can be regulated, and the fault current will be limited to a certain level. Control strategies consist of fault detection and PWM converter operation is designed. To simplify the design of controllers the mathematical equations can be expressed in synchronous rotating d-q frame. Furthermore, under the condition that the active SFCL is placed behind the relay element, its current-limiting impedance will be added into the measured impedance between the relay and the fault points. As a result, in order to prevent the refused operation of the relay, According to the two different operation modes of the active SFCL, in this paper present the corresponding two modified formulas. Using MATLAB SIMULINK, model of the three phase AC system with ASFCL is created and control strategies test, fault current limiting test, and distance relay operation is investigated. [ABSTRACT FROM AUTHOR]

In this paper, a new control strategy for dynamic voltage restorer (DVR) is presented to compensate effectively voltage sags. In this strategy, load and supply voltage magnitude and angle are estimated by least error square filters in short time. The advantage of this method is reducing noise, distortion, and harmonic on estimation parameters. Accordingly, these parameters are controlled for each phase separately. Also, it should be noted that due to the phase angle estimation by LES filters, the control system does not require phase-locked Loop and this issue causes an increase in speed of control system response. In addition, a P+Resonant and Posicast controller are used to eliminate the steady-state error and improve transient response in DVR, respectively. The proposed control system is simulated, using PSCAD/EMTDC software by induction motors starting is connected to 13 bus IEEE standard network. Finally, the simulation results prove that the proposed control scheme performs satisfactorily under sudden changes of load. [ABSTRACT FROM AUTHOR]

This paper presents a study about of a fuzzy Controlled STATCOM, which can be applied for mitigation of the voltage flicker in a distribution system. The voltage flicker is produced by a large variable load absorbing continuously changing currents such as an arc furnace. The DSTATCOM includes a voltage-sourced PWM inverter and its control system. The control strategy of the DSTATCOM plays an important role in maintaining the voltage flicker. Here, the DSTATCOM controller is designed with two types of controllers, linear proportional-integral (PI) and nonlinear fuzzy logic. The simulation of the DSTATCOM with 3MVar reactive power on a 25 KV distribution network is carried out in MATLAB/SIMULINK software. At the end of the paper, fuzzy controllers were evaluated by comparing its performance with the PI controllers. It is observed that the fuzzy controllers are very superior in mitigating the voltage flicker. [ABSTRACT FROM AUTHOR]

The main objectives of distribution network reconfiguration are real power loss reduction and relieving the overload. As well, integration of distributed generation (DG) units and fixed/switched capacitor banks are effective options for operation cost reduction, reducing system losses, improving voltage profile and increasing voltage stability index in the distribution systems. Therefore, simultaneous network reconfiguration, optimal placement of DG units and fixed/switched capacitor banks are proposed in this paper. The dedicated genetic algorithm is proposed for simultaneous network reconfiguration and allocation of DG units and fixed/switched capacitor banks in distribution systems considering different load levels. The proposed approach is able to find good network configurations and determine the optimal site and size of DG units and fixed/switched capacitor banks in distribution systems, simultaneously. The considered objective function encompasses the total cost of power loss, the investment and operation costs of DG units, the installation cost of fixed/switched capacitor banks and cost of purchased active power demand from upstream network. The proposed method is applied to 69-bus distribution system. The simulation results and comparison of different scenarios reveals that the simultaneous network reconfiguration and allocation of DG units and fixed/switched capacitor banks, results in significant advantages in the total cost. [ABSTRACT FROM AUTHOR]

This paper provides an algorithm of fault resistance compensation for digital ground distance relay considering the voltage and current transformer effects. Performance of the conventional ground distance relaying manner is adversely affected by different ground faults and also typical type, called a simultaneous open conductor and ground fault. The proposed scheme by using local-end data only, has shown satisfactory performances under wide variations in fault location, with different values of fault resistance and having positive and negative of power transfer angle. The presented method which has been carried out on the IEEE 14 bus benchmark is executed in PSCAD/EMTDC and MATLAB software, and the results show the accurate performance of mentioned configuration. [ABSTRACT FROM AUTHOR]

Nowadays, due to increased consumption and operation of electric power systems close to their stability boundaries, power systems may become unstable during severe disturbances. So, it is very important to determine the stability margin under different conditions. In this paper, the static voltage stability of an interconnected power system considering load and generation uncertainties is evaluated using probabilistic power flow. The Monte Carlo Simulation method is used to generate the probabilistic power flow scenarios. Then, the expected static voltage stability index and probability of stability for all of the PQ buses are obtained. Also, the standard deviations of the stability indexes are calculated. Finally, the critical PQ nodes are determined under given disturbance. The study has been carried out on 39-Bus New England and 118-bus IEEE test systems and results are presented. [ABSTRACT FROM AUTHOR]

In this paper we have proposed a new switch or structure for reducing actuation voltage. This switch is compared with four conventional structures considering the force range of 1uN to 3uN. We have used the ANSYS software for design and simulation for the switch parameters such as actuation voltage, collapse voltage, spring constant and resonant frequency. Small size (half of the size of other proposed materials), which can reduce the manufacturing cost, and also low-valued spring constant, which results in actuation voltage reduction, are among more noticeable features of the proposed switch. [ABSTRACT FROM AUTHOR]

In the modern context of electricity market deregulation, the price of the kilowatt-hour must take both power injections and withdrawals of the multiple market participants into consideration, as well as their actual grid usage. The responsibility for causing transmission losses and voltage drops therefore, needs to be fairly attributed. While grid power injections and withdrawals are unequivocally attributed, it remains to date impossibly to naturally share responsibility for transmission losses. Relevant literature proposes a variety of methods. This paper proposes a new method for allocating transmission losses to market participants by using the network. The overall grid losses are obtained from summing the difference between injected and withdrawn power for all nodes. A set of allocation factors derived from the electrical distance between concerned buses and their voltage levels that is used to attribute active power loss to each bus, after the losses which are arising from the mutual influencing between buses has been calculated. This method focuses on bus bar current injections and it assumes which there is a hypothetical power flow between nodes. For mutual influencing, one of the bus bars is considered a generator and the other is a load. A reference bus voltage is set and then the load side is penalized depending on how far its own voltage is lower than that reference value. Results from a sample network are compared to those of previous methods. [ABSTRACT FROM AUTHOR]

Reactive power dispatch plays a key role in secure and economic operation of power systems. Optimal reactive power dispatch (ORPD) is a non-linear optimization problem which includes both continues and discrete variables. Due to complex characteristics, heuristic and evolutionary based optimization approaches have become effective tools to solve the ORPD problem. In this paper, a new optimization approach based on improved differential evolution (IDE) has been proposed to solve the ORPD problem. IDE is an improved version of differential evolution optimization algorithm in which new solutions are produced in respect to global best solution. In the proposed approach, IDE determines the optimal combination of control variables including generator voltages, transformer taps and setting of VAR compensation devices to obtain minimum real power losses. In order to demonstrate the applicability and efficiency of the proposed IDE based approach, it has been tested on the IEEE 14 and 57-bus test systems and obtained results are compared with those obtained using other existing methods. Simulation results show that the proposed approach is superior to the other existing methods. [ABSTRACT FROM AUTHOR]

Since the development of wind power plants installation is growing, problems which are related to network connecting, stability and voltage effects become more important. On the other hand, wind farms are often open to lightning because of their long height and specific appearance. In this paper, modeling and simulation of 1-phase, 3- phase and lightning faults in a wind farm consisting of 40 wind turbines and faults impact on wind farm and the network is investigated in EMTP-RV environment. In this field, it's necessary to develop a precise modeling out of wind power plant in order to evaluate the effects of these power plants on dynamical behavior of the power system. These models can be used in designing new protection systems, new protection algorithms, and new strategies for power plants exploitation improvement. Each wind unit in the farm is connected to the whole units that are connected to the network using a doubly fed induction generator (DFIG). [ABSTRACT FROM AUTHOR]

In this paper for the first time, a circuit model for multi-finger I-gate body-contacted silicon-on-insulator MOSFET is presented. The model parameters are adjusted using simulation of a 45 nm SOI nMOSFET. Using the model, typical body voltage for a 35 finger device is obtained and applied to the transistor. The threshold voltage and drain current are obtained for the first transistor and center ones in the multi-finger structure. The drain induced barrier lowering of the center transistor is increased by 30% and off-current 40 times than that of the first transistor. Simulation results verified the I-gate body contact model in lack of controlling the body voltage comparing with the conventional body contacts e.g. H-gate. [ABSTRACT FROM AUTHOR]

Induction motors are widely used in industrial, commercial and residential applications. An induction motor may exposed to the unbalanced voltage in the various operating conditions. Therefore, it is vital to investigate influences of voltage unbalance on performance of induction motors. In this paper, the performance of a three-phase squirrel cage induction motor has been simulated using Finite Element Method(FEM) supplied by different unbalanced voltages with the same Voltage Unbalance Factor(VUF) as well as the same positive-sequence phase voltage components. In addition, input/output powers, losses and efficiency of the simulated motor under mentioned conditions have been studied. [ABSTRACT FROM AUTHOR]

Three new SRAM cells are proposed in this paper. Increasing area overhead is the major concern in SRAM design. One of the new structures is included four transistors instead of six transistors as it is used in conventional 6T-SRAM cell for very high density embedded SRAM applications. The structure of proposed SRAM employs one word-line and one bit-line during Read/Write operation. The new SRAM cell has smaller size, leakage current and power dissipation in contrast of a conventional six transistor SRAMs. A proposed 4T-SRAM cell has been simulated for 256 cells per bit-line and 128 columns cell for supply voltage of 1.2V. Furthermore, two other new structures are included 10 and 11 transistors. These new structures have been separate read and write process by changing in the structure of conventional 6T SRAM to achieve high Static Noise Margin (SNM). Using 10T and 11T SRAM cells lead to apply 512 cells per bit-line by reducing leakage current technique, while the cell is unavailable. 128 columns cell array has been built to measure the operation of SRAM cell. To have low power dissipation, the supply voltage for 10T and 1 1T are chosen 0.32V and 0.27V, respectively. Proposed SRAM uses one read bit-line during read operation. Simulation results have been confirmed by HSPICE in 0.13um process. [ABSTRACT FROM AUTHOR]

Design and simulation results of fully integrated 5-GHz CMOS LNAs are presented in this paper. Three different input impedance matching techniques are considered. Using a simple L-C network, the parasitic input resistance of a MOSFET is converted to a 50 Ω resistance. As it is analytically proven, that is because the former methods enhance the gain of the LNA by a factor that is inversely proportional to MOSFET's input resistance. The effect of each input impedance matching on the amplifier's noise figure and gain is discussed. By employing the folded cascode configuration, these LNAs can operate at a reduced supply voltage and thus lower power consumption. To address the issue of nonlinearity in design of low voltage LNAs, a new linearization technique is employed. As a result, the IIP3 is improved extensively without sacrificing other parameters. These LNAs consume 1.3 mW power under a 0.6 V supply voltage. [ABSTRACT FROM AUTHOR]

In this paper, voltage sag is compensated by the DVR (Dynamic Voltage Restorer) in distribution systems. This device is applied between the sensitive load and the supply in order to inject voltage in series to correct the voltage sag. Subsequently, all the other various DVR compensation techniques in the distribution system are explained. Due to the restriction of the energy storage in DVR's capacitors, it is essential to minimize the active power injected by the DVR. Thus, a minimum active power injection method is proposed to compensate the voltage sag. Performance of this method is evaluated under balanced and unbalance voltage sag in a distribution system. [ABSTRACT FROM AUTHOR]

One of the fundamental structures of inverters with soft switching is the use of quasi-resonant DC link (QRDCL) circuits, in which element switching occurs in the zero voltage (ZVS) and / or zero current (ZCS) conditions and also the use of pulse width modulation (PWM). One of the indices of distinction and superiority of these converters is losses in the QRDCL circuit, less losses, and the increase of converter's frequency. This paper aims to calculate losses of the QRDCL and the design control circuits of improved QRDCL voltage inverter. In this regard, at first, the benefits of soft switching and general characteristics of various types of topologies used in inverters with soft switching is studied and then, the desired improved inverter with the capability of EDPWM (Enhanced Double PWM) which uses the single-phase soft switching technique (SPSS) is introduced. For proper functioning of the circuit, a particular type of the sinusoidal pulse width modulation (SPWM) is used, which its characteristics is studied and then the desired control circuit inverter is proposed. Finally, the full simulation of the inverter is conducted and the obtained results of analyzing the functionality of the circuit and mathematical equations governing the circuit are compared with the results come from computer simulation. [ABSTRACT FROM AUTHOR]

This paper presents the comparative performance of neuro- Fuzzy controlled Voltage Source Converters (VSC) based Flexible AC Transmission System (FACTS) devices, such as Static Synchronous Series Compensator (SSSC), Static Synchronous Compensator (STATCOM), and Unified Power Flow Controller (UPFC) in terms of improvement in transient stability. In neuro-fuzzy control method the simplicity of fuzzy systems and the ability of training in neural networks have been combined. The training data set the parameters of membership functions in fuzzy controller. This Adaptive Network Fuzzy Inference System (ANFIS) can track the given input-output data in order to conform to the desired controller. The maximization of energy function of UPFC is used as an objective function to generate the training data. Proposed method is tested on a single machine infinitive bus system to confirm its performance through simulation. The results prove the noticeable influence of ANFIS controlled UPFC on increasing Critical Clearing Time (CCT) of system. [ABSTRACT FROM AUTHOR]

In this paper we proposed, a new zero voltage switching isolated buck-boost DC-DC converter with active clamp circuit. The active clamp circuit in this converter not only absorbs voltage spikes across the main switch but also provides soft switching conditions for all switches. All switches are Pulse Width Modulation controlled which simplifies the control implementation. One of the main advantages of this converter is operating at high power levels while soft switching conditions exist in both buck and boost modes of converter operation. Since this converter can operate over a wide input voltage range, it can be employed in power factor correction. The experimental results obtained from a 150W prototype circuit operating at 100 KHz are presented to confirm the integrity of the proposed circuit. [ABSTRACT FROM AUTHOR]

In this paper, a CMOS four quadrant multiplier based on flipped voltage follower and differential squaring circuit is presented. The proposed circuit has a compact architecture which operates at a higher speed and a higher input voltage range compared to the previously presented structures. The transistors operate in both saturation and ohmic regions. The circuit operates with a single supply voltage of 3.3V in a 0.35 μm CMOS technology where the total harmonic distortion (THD) is less than 1.1%, the linearity error is also less than 3%, -3db frequency is more than 180 MHz and the voltage input range is 3V p-p. Simulation results are given to verify the functionality of the proposed multiplier. [ABSTRACT FROM AUTHOR]

This paper presents a dual-active capacitance in reversed nested Miller compensation (DACRNMC) technique for low-voltage and large capacitive load amplifiers. The frequency bandwidth of the DACRNMC amplifier has been improved due to the usage of active compensation capacitors. The amplifier's die area is reduced in compare to the existing techniques in the RNMC scheme. The architecture also generates two left half plane zeros to increase the phase margin. The simulation for the proposed DACRNMC amplifier with a 0.18μm standard CMOS process reveals a unity gain bandwidth of 17.4MHz and phase margin of 64 degrees , while 500 pF load is driven from a single 1.5 V power supply. [ABSTRACT FROM AUTHOR]

In this paper a new implementation of CMOS ripple comparator cell using the Gate-Diffusion Input (GDI) technique is presented. The proposed design using this technique allows for the reduction of power consumption, propagation delay, and the area of digital circuits while maintaining low complexity of logical design. The performance comparison with standard CMOS and GDI logic design techniques is presented. These methods are compared with respect to the number of devices, PDP, and power dissipation. Simulation results confirm that the proposed cell can work at low supply voltage and dissipates low power. [ABSTRACT FROM AUTHOR]

In this paper the power flow control at power systems in the presence of distributed generation is analyzed. The work proposes use of Unified power flow controller (UPFC) to control the power flow at the load bus by Main supply in coordination with DG source. This work shows that using UPFC leads to the reduction of the oscillation power and voltage at the time of three phase fault in the system. The studies are performed based on the well known software, MATLAB/SIMULINK Simulation results show that the stability and effectiveness of the applied operation of DG source in coordination with the main utility can be achieved by using UPFC. [ABSTRACT FROM AUTHOR]

Considering the wide usage of induction motors in various industries and the limitation of applying speed sensors in some cases, sensorless drives have became very important and the challenge to increase the accuracy of estimation continues. This paper presents a novel method for sensorless speed control for IM's that not only improve the estimation and speed tracking in DTC but also eliminate the speed sensor in DTC. For this purpose all needed parameters for sensorless speed control such as stator flux, speed and load torque are estimated with the extended Kalman filter. In this method, noise due to system structure, voltage, and current sampling is eliminated in all the effective parameters. Simulation results show the increase in the precision of estimation and speed tracking. [ABSTRACT FROM AUTHOR]