Sharif Digital Repository

Reliability is one of the main factors influencing customer loyalty in a competitive power industry. The system operator must ensure that there is sufficient spinning reserve to maintain system security. Contractually such commodity requires a willing buyer and a willing seller. A novel pool-based market clearing algorithm for spinning reserve procurement and the cost allocation associated with provision of spinning reserve among DisCos is developed in this paper. Rational buyer model is used for energy and reserve market model. In the proposed algorithm, generating units bid simultaneously to energy and spinning reserve markets and these markets are sequentially cleared. In such a market,... 

LLC resonant converter has been widely used in dcdc converters. In this paper, optimum dead-time and maximum switching frequency of a wide-adjustable-range LLC resonant converter are investigated for realizing the zero voltage switching (ZVS) operation even under the worst-case conditions. Analyses demonstrate that these parameters depend on the converter inductance ratio and ratio of the converter resonant capacitor and the effective capacitance appeared in parallel with the drainsources of the power MOSFETs. The necessary dead time for realizing the ZVS operation can be minimized by choosing the normalized maximum switching frequency, properly. Using the dead-time optimum value, soft... 

LLC resonant converter with significant resonant inductance is proposed for designing an adjustable wide-range regulated voltage source. Large resonant inductance increases output voltage adjustment range and conversion efficiency, particularly at light loads. Soft switching is achieved for all power devices under all operating conditions by choosing the dead time and maximum switching frequency properly and operating in the converter's inductive region. Using a power-factor-correction (PFC) converter reduces the resonant converter's output voltage dependence to the variations of the main ac input voltage. Thus, the compensation of the load variations and the wide-range adjustment of the... 

Proton Exchange Membrane (PEM) Fuel Cells are attracting most of the electricity consumers because of high efficiency, zero carbon emissions and high reliability. There are many parameters influencing on this power source's operation. A model of PEM fuel cell will be presented and the sensitivity of the fuel cell's parameters will be analyzed. Multi Parameters Sensitivity Analysis is used next to examine the relative importance of the influential parameters on the PEM fuel cell operation  

Soft errors due to cosmic radiations are the main reliability threat during lifetime operation of digital systems. Fast and accurate estimation of soft error rate (SER) is essential in obtaining the reliability parameters of a digital system in order to balance reliability, performance, and cost of the system. Previous techniques for SER estimation are mainly based on fault injection and random simulations. In this paper, we present an analytical SER modeling technique for ASIC designs that can significantly reduce SER estimation time while achieving very high accuracy. This technique can be used for both combinational and sequential circuits. We also present an approach to obtain... 

Advance Encryption Standard (AES), has received significant interest over the past decade due to its performance and security level. In this paper, we propose a compact 8-bit AES crypto-processor for area constrained and low power applications where both encryption and decryption is needed. The cycle count of the design is the least among previously reported 8-bit AES architectures and the throughput is 203 Mbps. The AES core consumes 5.6k gates in 0.18 μm standard-cell CMOS technology. The power consumption of the core is 49 μW/MHz at 128 MHz which is the minimum power reported thus far  

Fuel Cell (FC) is one of the promising distributed generation resources which are based on renewable energies. Clean electricity generation, high efficiency and high energy density of the fuel cells make them attractive for lots of engineers. In this paper we discuss about the operational principles of fuel cell generally. Then, a circuit model of them will be introduced. Based on the model, we designed a novel DC/DC converter for supplying the fuel cell's load and simulated the design with using Matlab. The results say that its novel converter could conveniently supply the load and its needed power curve. ©2009 IEEE  

Power Distribution Unit (PDU) is a power supply unit that supplies various DC voltage levels for electric equipment. Reliability of PDU is very important in electrical systems. Buck converter is frequently used in PDU to provide the lower voltage levels than the source voltage level. The output capacitor of the buck converter is the main factor of failure. In this paper, we present a method to design a buck converter with almost no inductor current ripple. If the inductor current ripple is eliminated, the output capacitor can be removed from the converter. By removing the capacitor, the reliability and transient response of the converter can be improved considerably. The proposed method is... 

In switching power supplies, the transformer leakage inductance (TLI) is of considerable practical significance. Ordered winding is the certain assumption in previously reported works for the calculation of the TLI value. However, disordered windings are usually unavoidable in practice and their effect on the value of the TLI is considerable. The problem becomes more complex when the number of winding turns increases. In this paper, the effect of winding disorder on the TLI value is investigated. In disordered wrapping, the winding turns arrangement (WTA) of each produced transformer is different from the others. Thus, each produced transformer has an exclusive TLI value in a disordered... 

This paper presents a single-ended low-power 7T SRAM cell in FinFET technology. This cell enhances read performance by isolating the storage node from the read path. Moreover, disconnecting the feedback path of the cross-coupled inverters during the write operation enhances WSNM by nearly 7.7X in comparison with the conventional 8T SRAM cell. By using only one bit-line, this cell reduces power consumption and PDP compared to the conventional 8T SRAM cell by 82% and 35%, respectively. © 2018 Elsevier GmbH  

In this paper, a novel closed form expression is derived to find the Green's function of a horizontal electric current in a parallel-plate waveguide. It is achieved by expanding the Green's function into a series of Gaussian functions. This new method is called the Gaussian Green's function (GGF) method. The main advantage of the GGF method lies in its precision as well as rapid convergence. Numerical results confirm that the closed form expression yields less than 0.2% error compared to the numerical integration of the spectral integral. Furthermore, it is verified that this method can be in excellent agreement with the complex images (CI) method. © 2008 IEEE  

This paper presents several techniques for the processing of power system signals in a power system setup. The techniques exhibit a desirable performance against signal pollutions such as noise and distortions, signal unbalance (in three-phase applications), and Variations in the signal attributes (mainly its frequency). These features render them a promising set of options for modern power systems in which all or some of these undesired factors may be amplified depending on the case. Single-phase and three-phase applications are both examined and appropriate techniques are suggested for different scenarios. © 2007 IEEE  

Serious and challengeable role in markets of low power supplies for cellular phones and other small portable devices is expected for single fuel cell in future. Single fuel cell voltage level is extremely low in comparison with its output current. According to the extremely low level of the voltage, a suitable dc/dc boost converter must be used for increasing the voltage. In this paper, a model for a single fuel cell is presented and the effect of external load variation and changing of reactant pressure on cell performance is investigated. Moreover, a predictive voltage controller for boost convertor of PEM fuel cell is presented, simulated and validated using MATLAB/Simulink. The results... 

One of important subjects in power system restoration that already is not addressed is frequency control. Operators are often concerned with the size of load and generation, which can be safely increased. With the emphasis on higher utilization of power systems, monitoring of its dynamics is becoming increasingly important. This requires information with higher accuracy and update rates faster than those usually provided by traditional SCADA systems. In addition, it must be synchronized over a wider geographical area than that provided by traditional protection systems. Nowadays, the introduction of Phasor Measurement Units (PMU) and Wide Area Monitoring Systems (WAMS) as well as advances in... 

The objective of the research done in this paper was to determine cost of the power and heat system with pressurized fluidized bed gasifier using exergoexonomic appraisal techniques. Exergetic efficiency maximization was approached with use of multi-objective evolutionary optimization methods which were designed such that the costs were minimized in line with the exergoeconomic plans. The results of this method were also compared to methods that employ iterative techniques. Results showed an almost 12.28% improvement in exergetic efficient that the system could reach through utilization of the multi-objective evolutionary algorithm  

This paper presents a novel sectionalizing method for the build-up strategy in power system restoration. Power system restoration is the procedure of restoring power system elements after a partial or a complete blackout. Because of its economic and political importance, different strategies have been developed for power system restoration. One of the most practical and economical is the build-up strategy that includes the process of restoring separated parts (islands) in the power system and interconnecting them afterwards. This paper intends to develop a systematic algorithm for sectionalizing a power system considering various constraints such as black-start capability of generators,... 

Triple Modular Redundancy (TMR) is a historical and long-time-used approach for masking various kinds of faults. By employing redundancy and analyzing the results of three separate executions of the same program, TMR is able to attain excellent levels of reliability. While TMR provides a desirable level of reliability, it suffers from the high power consumption of the redundant hardware, a severe detriment to its broad adoption. The energy consumption of TMR can be mitigated if its operations are divided into two stages, and one stage is dropped in the absence of fault. Such an approach, which is evaluated in recent research, however, quickly fails in the presence of permanent faults, as we... 

Triple Modular Redundancy (TMR) is a historical and long-time-used approach for masking various kinds of faults. By employing redundancy and analyzing the results of three separate executions of the same program, TMR is able to attain excellent levels of reliability. While TMR provides a desirable level of reliability, it suffers from the high power consumption of the redundant hardware, a severe detriment to its broad adoption. The energy consumption of TMR can be mitigated if its operations are divided into two stages, and one stage is dropped in the absence of fault. Such an approach, which is evaluated in recent research, however, quickly fails in the presence of permanent faults, as we... 

In this paper, a low power receiver for medical implant communication service (MICS) is presented. Low power design is vital in the MICS applications since the implanted chip has to work for a long time without the need to change its battery. As a result, a merged N-path low noise amplifier (LNA) and mixer block is proposed. In this structure, the LNA and down-conversion mixer share a transconductance to lower the overall power consumption. An N-path feedback is utilized around the shared transconductance not only to improve the LNA selectivity and relax the linearity requirements but also to downconvert the radio frequency (RF) component and create the intermediate frequency (IF) signal. In... 

Operation of transmission lines are usually limited by stability limits rather than thermal capacity limits. Thermal limit of transmission lines is a physical limitation of their components and not related with the overall power system characteristics, but stability limits are strictly related with power system characteristics. This paper presents an approach for increasing stability limits using PSS. © 2008 IEEE