Advanced Materials Research Vols. 931-932

Abstract: HDPE plastic wastes were fast pyrolyzed at temperature of 400-450°C and char (solid residues) obtained were collected and analyzed. Proximate and ultimate analyses showed that pyrolysis char had a large amount of volatile matter (51.40%) and fixed carbon (46.03%), small amount of moisture (2.41%) and little amount of ash (0.16%). Contents of carbon, hydrogen, nitrogen, and sulfur were found to be 42.65, 3.06, 0.43%, and 1.80%, respectively. Calorific value and density of the char were also determined and reported as 4,500 cal/g and 1.59 g/cm³, respectively. Char derived from the fast pyrolysis of HDPE plastic wastes was crushed into powder and extruded to produce briquettes. One kilogram of the char based briquette was used as a fuel for the combustion process (boiling water). Atmospheric-pressure thermal activation at 900°C for 3 hours was performed to promote surface area and specific pore volume of the char. Undergoing such an activation process, BET surface area and pore volume of the char were increased by 55% and 44% whereas pore size was reduced by 5%, corresponding to the values of 16.77 m²/g, 0.2080 cm³/g and 496 Å, respectively.

Abstract: Zinc Oxide (ZnO) surge arresters (SAs) experience thermal runaway when the temperature exceeds the acceptable limit. This phenomenon is associated with the increase in resistive leakage current due to degradation. This paper presents the electrical performance of ZnO SAs in 22 kV distribution system using thermal image camera under the power frequency AC operating voltages. When ZnO surge arresters are installation takes a long time in distribution system over than 5 years. For the experimental study, as ZnO installation takes a long time over than 6 years the leakage current is 63.9 mA, temperature difference were measured over a period of time over than 14 degree Celsius. This data will be useful as a guideline for solving problems and reducing power loss from leakage current. Moreover, it will be useful in predicting lifetime of ZnO SAs.

Abstract: Electrical energy generating from power plant is transmitted to electrical substations via high-voltage transmission lines. After a certain period time of use, the transmission line is required for maintenance such as insulator replacement. To avoid power interruption during insulator replacement, a corrective maintenance, hot line maintenance, is performed. This research focused on the hot line insulator replacement of 230 kV Bangsapan-Chumporn and 230 kV Chumporn-Suratthani transmission lines transferring power between southern and central regions of Thailand. The maintenance of 230 kV double suspension string for two bundles with arcing horn required developed C.B.T. hot end yoke tool to enhance stability and availability of electrical energy during hot line insulator replacement. C.B.T was named by the initial letter of the name of Chumporn Bandon and Takuapa transmission lines under authorization of the maintenance section in responsible maintaining service of transmission lines in upper southern provinces. The developed C.B.T hot end yoke device for hot line insulator replacement could save about 2.67 million bahts during 7-hour of maintenance time of EGAT payment.

Abstract: In this paper, we present our study of the 22 kV power distribution network at Sisaket substation in Vientiane. Based on the simulation using Digsilent power factory software (DPFS), the protection device, particularly fuses and the reclosers, can be coordinated in time to better protect the system against both temporary and permanent faults, and consequently, the reliability of the system can be improved. Furthermore, the saving fuse and choosing the new protection device to prevent the distribution network is considered in this paper.

Abstract: This paper proposesthe coordination between recloserandfuse link, reclosertorecloser, and recloserwith over current relay in tie feeder 1, 2ofDonekoy substationin Laos PDR.Disilent power factory software is used for simulation toimprove the operation of protective devicesand analyze the operating timein the distribution system.The operating coordination of recloser, fuse and overcurrent relayis improved. Resetting their functionality to limit the fault,the coordinating power aimsto reduce the problems of outages on distribution and also makes the system reliability.In case of maintenance circuit breaker, the 22 kV - tie bus applies to loads feeder 2 to ensure the stability power to appliances load of customers.Therecloser3 was installed on feeder 2 to protect the faults,and coordinates with recloser2 while the short circuit occursat fault2.

Abstract: The stochastic stability analysis method is proposed in this paper to investigate the small signal stability (SSS) of the single machine infinite bus power system. An induction generator wind turbine model is examined including frequency dependent load. The first integral energy function method is applied based on Lyapunovs stability and the theory of stochastic stability. This proposed method can investigate effects of stochastic wind power and load quantitatively while the general deterministic methods cannot.

Abstract: In this paper, a technique to improve the transient response of a parallel-connected AC/DC converter has been studied. The proposed technique is used to improve the transient response while disturbance is injected into the system. Generally, a conventional voltage loop control uses a PI controller, because of which a slow transient response is observed. In this paper, the voltage loop control is composed of a signal from the PI controller added with a peak input current and gain scheduling of change in peak input current. The performance evaluation was experimented on a three-module isolated CUK AC/DC converter, with a 500W load and-48V DC output voltage. The system achieves the following: tight output voltage regulation, good current sharing, and low harmonic distortion. Moreover, the disturbance occurs in the system by an immediate load change, and the output voltages are at minimum overshoot and undershoot with a fast settling time.

Abstract: This paper presents a two-phase interleaved boost converter with nonlinear control for solar cell applications. The advantage of the interleaved technique is the reduction of the ripple current drawn from the energy sources. Traditionally, to control a DC-DC converter, a linear multiple-loop feedback control technique is often used. In this paper, we propose a nonlinear control technique which is based on Flatness system properties for the voltage loop and a nonlinear control based on sliding-mode for the current loop. The main feature of the used controller is that it can control the converter at any operating point. The validation of the proposed system is demonstrated through experimental results.

Abstract: This paper proposes a wireless power transmission system which used a printed circuit board operating as an antenna for both transmitter and receiver. The proposed antenna is driven by a high frequency full-bridge inverter which operates at self-resonant frequency of the antenna. Design procedure for the proposed antenna is also described. Results obtained from experimental test-rig confirm that the fabricated antenna provides self-resonant frequency at 2 MHz as design. The efficiency of the antenna can achieve the highest when the distance between transmitter and receiver is 40 mm in vertical alignment. The maximum total efficiency of proposed system is approximately 56.7 % at the distance between transmitter and receiver of 80 mm.

Abstract: This paper presents a full-bridge MOSFETs driver circuit which can be operated in PWM mode. The proposed circuit consists of capacitors, resistors and, diodes. The input signals for the proposed driver do not need external dead-time generator circuit because the dead-time generator is already integrated into the proposed full-bridge driver. The experimental results show that the proposed full-bridge driver circuit can be operated at 4 kHz sinusoidal PWM at 315 volt DC link. The power output of prototype inverter is 45 watt.