Papers by Keyword: Power Factor

Abstract: The recent revitalization of Ioffe plots (entropy conductivity versus electrical conductivity) reminds us that Isotan (Cu55Ni44Mn1) is an outstanding thermoelectric material with a power factor of up to 60 W cm^-1 K^-2 at a specific electrical conductivity of almost 20,000 S cm^-1 at elevated temperature. Even though, Isotan is widely used in thermoelements for temperature measurement, its high open-circuited thermal conductivity of approximately 70 W cm^-1 K^-2 [1] hindered further research as a promising thermoelectric material. Isotan was chosen as a starting composition. Influence of partial substitution of Cu and Ni with heavy elements (Sn,W) on the thermoelectric properties was studied. The alloys were fabricated by arc-melting and microstructurally characterized for grain size and elemental composition by scanning electron microscope (SEM) combined with energy-dispersive X-ray (EDXS). Lattice symmetry and parameters were estimated by X-ray diffraction (XRD). Functional properties as Seebeck coefficient, electrical conductivity and power factor were used to evaluate the thermoelectric performance.

Abstract: In this work, we use first principles DFT calculations, anharmonic phonon scatter theory and Boltzmann transport method, to predict a comprehensive study on the thermoelectric properties as electronic and phonon transport of layered LaSe₂ crystal. The flat-and-dispersive type band structure of LaSe₂ crystal offers a high power factor. In the other hand, low lattice thermal conductivity is revealed in LaSe₂ semiconductor, combined with its high power factor, the LaSe₂ crystal is considered a promising thermoelectric material. It is demonstrated that p-type LaSe₂ could be optimized to exhibit outstanding thermoelectric performance with a maximum ZT value of 1.41 at 1100K. Explored by density functional theory calculations, the high ZT value is due to its high Seebeck coefficient S, high electrical conductivity, and low lattice thermal conductivity .

Abstract: Polyaniline (PANI) has been considered for thermoelectric (T.E) applications due to its facile preparation methods, easy doping-dedoping processes and its environmental stability. Like other conducting polymers (CPs), it has low thermal conductivity (usually below 1 Wm^-1K^-1) which is favorable for T.E applications, however studies have shown that it still suffers from low power factors as a result of low electrical conductivity. For this reason, PANI has been compounded with other materials such as polymers, inorganic nanoparticles and carbon nanoparticles to enhance its electrical conductivity, power factors (PF) and ultimately zT value.This work is focused on the synthesis and characterization of n-type polyaniline nanocomposites doped with reduced graphene oxide (rGO). The rGO was prepared through oxidation of graphite and subsequent reduction and incorporated into polyaniline through in situ polymerization and the resulting nanocomposites were characterized. Addition of rGO resulted in enhancement of the electrical conductivity of polyaniline from 10^-3 S/cm to 10^-1 S/cm which is two orders of magnitude higher. This contributed to the enhanced PF, an indication that thermoelectric behavior of conducting polymers can be boosted through compounding with inorganic materials.

Abstract: This article presents theory of The design of medium sized voltage capacitor in order to improve the Power Factor Value to AC motor. In present, the electrical power system has focus on improving the Power Factor significantly because it is the major key to increase or decrease the applicable expenses. The power system that has low power factor will have a lot of loss to system, especially when electrical voltage is on voltage medium. When power factor has been adjusted, the system can take more loads and electrical power loss is decreased. It also decreases voltage in power line and decreases electrical bills at the same time. This article presents the theory to analyze data from motor that needs to adjust a power factor so that it pass electricity authority standard by considering the efficiency of the motor so that the consumers do not have to pay the penalty of the Power Factor Value differences to the Electricity Authority. Furthermore, it can help decrease the bills of unstandardized electrical power which occurred in the system and enable the system to take more loads at the same time.

Abstract: According to harmonics pollution and low power factor problems of the traditional switching power, the design is a switching power of high power factor based on UCC28019 chip used on 3D printers. This design has the advantages of high power factor, high efficiency, low harmonics and low noise. Main circuit passes through EMI filtering, full-bridge rectifier and then filter, Boost chopper boost and correction of active power factor and closed-loop controlling, making the output voltage stable, small interfering and high over-all efficiency.

Abstract: At present, the control system of electric traction motors is widely used in four-regulators collected on thyristors in a bridge rectifier circuit. The feature switching processes in them are needed to introduce an artificial delay of the thyristors opening angle, which reduces the average value of the power factor up to 0.8. The article assesses the effectiveness of the combination of the rectified voltage from the point of view of increasing the energy performance of the band rectifiers for controlling the traction motor freight locomotives operating on alternating current. With this regulation the greatest effect is achieved in the first control zone, under normal conditions when the power factor is particularly low (0.2 ... 0.6). The expected improvement of the average power factor of the first zone will be about 22%, and taking into account the duration of the performance in all working areas, it should be about 5-10%

Abstract: This paper discusses the optimal Distributed Generator (DG) coordination using the Particle Swarm Optimization (PSO) technique where the DG output and location are determined simultaneously. Furthermore, this study analyzes both single DG and multiple DGs configurations. The influence of DG Power Factor (PF) to the optimal DG placement and the DG output are investigated by varying the DG PF values. Specifically, the PF were configured to five values, which are 0.8, 0.85, 0.9, 0.95 and 1.0. From the results, the optimal DG placements are similar, regardless of the PF condition. For example, in the single DG unit experiment, the optimal DG location is at bus 6 whilst in the triple DG units test, the optimal locations are at busses 14, 24, and 30. In contrast, the value of PF significantly influences the optimal DG output and power loss reduction. This study concludes that the design with three DGs where their PFs are configured to 0.8 has the least power loss.

Abstract: In this paper we reported the electrical conductivity and thermoelectric characterization of silver (Ag) and antimony (Sb) co-doped lead telluride bulk materials, which have been synthesized using solid state microwave technique. The doping level has performed first-principle calculations for the AgPb_mSbTe_m+2 (LAST-m) (m = 0, 2, 4, 6, 8 and 10) to clarify the effect of simultaneous doping of Ag and Sb on PbTe. The Hall effect and thermoelectric measurements have shown n-type conductivity in AgPb_mSbTe_m+2 samples. The samples show large and negative values of the Seebeck coefficient and moderate electrical conductivity. The Seebeck coefficient increased with doping levels increases at m=0 to 10. The value of the Seebeck coefficient is −419.69 μVK⁻¹ for AgPb₈SbTe₁₀ at 338 K. It has been found that AgPb₈SbTe₁₀ sample has a higher thermoelectric power factor 1.87 mW K^-2 m^-1 at 310 K.

Abstract: This paper presents a training system based on low-voltage cascaded PWM STATCOM.It is intended to train the employee in power grid companies.The system is characterized by load disturbance in 380-V power grid and imaginary power compensation of transformerless cascade PWM STATCOM with star-configuration. A two-hierarchy DC voltage balance strategy is adopted to stabilize the H-bridge capacitors in the compensation procedure. Simulation and experimental waveform indicate that a 380V-20kvar cascade STATCOM with star-configuration compensate the the imaginary power shortage within 20ms.

Abstract: In view of limitations function, cost and application in domestic meter at present, this paper was designed the low power consumption, low cost smart meters and PC system based on microprocessor MSP430F4794. It supports multi rate, step rate and power factor influence factor of electricity metering method, and can realize the real-time clock, timing backup data, monitoring the temperature and humidity of the environment and other functions, has the ability to forecast the next period of time energy consumption and carbon dioxide emissions of electrical appliances. Combined with the PC software, the backup data of smart meters to report, detailed list, and the data curve method is presented to the user, and facilitate to analysis of user. The whole embedded in smart meters and the host computer system provides a good human-computer interface, can realize the user personalized service configuration and software calibration function.