• The Journal of the Korea institute of electronic communication sciences
• /
• v.17 no.3
• /
• pp.459-466
• /
• 2022

Switching surges are a common type of phenomenon that occur on any sort of power system network. These are more pronounced on long transmission lines and in high voltage converter stations. At AC/DC hybrid transmission lines, the insulation coordination of such lines is mainly dictated by the peak level of switching surges, the most dangerous of which include three phase line energization and AC/DC converter station. The power system structure consist of AC/DC hybrid transmission lines which is combination of AC 765kV and ±500kV HVDC 1 bipole system for contingency analysis. The power system under study and its components are simulated using EMTDC software package, the effects of the various AC/DC mixing power lines are reviewed. The developed models of EMTDC conversion lines based on combination of AC/DC system are simulated and the characteristics of switching surge over-voltage from its results are discussed.

• Journal of Electrical Engineering and Technology
• /
• v.13 no.4
• /
• pp.1682-1691
• /
• 2018

Natural ester is a suitable substitute for mineral oil and has been widely used in AC transformer in many countries. In order to further application of natural ester in direct current (DC) equipment, it is needed to investigate its long term insulation property under DC condition. In this paper, a thermal ageing experiment was conducted for both mineral oil-paper and natural ester-paper insulation. The DC breakdown and space charge characteristics of insulation paper impregnated with natural ester and mineral oil was compared. Results show that the resistivity of the paper immersed in natural ester and mineral oil both increase as the ageing goes on. While insulation paper impregnated with natural ester has higher resistivity and DC breakdown voltage than the paper impregnated with mineral oil. The DC breakdown voltage for the oil impregnated insulation paper being DC pre-stressing is higher than that without pre-stressing. The average DC breakdown field strength difference between the test with pre-stressing and without pre-stressing clearly shows that there is an apparent enhancement effect for the homo-charge injection on the DC breakdown.

• The Transactions of The Korean Institute of Electrical Engineers
• /
• v.62 no.8
• /
• pp.1125-1131
• /
• 2013

Wireless power transmission technology has been studied variety. Recently, wireless power transmission technology used by resonance and magnetic induction field is applied to various fields. However, magnetic resonance and inductive coupling are have drawbacks - power transmission distance is short. Microwave transmission and accept techniques have been developed to overcome short distance. However, improvement in efficiency is required. This paper, propose a high-efficiency microwave energy acceptor IC(EAIC). Suggested EAIC is consists of RF-DC converter and DC-DC converter. Wide Input power range is -15 dBm ~ 20 dBm. And output voltage is boosted up to 5.5 V by voltage boost-up circuit. EAIC can keep the output voltage constant. Available efficiency of RF-DC converter is 95.5 % at 4 dBm input. And DC-DC efficiency is 94.79 % at 1.1 mA load current. Fully EAIC efficiency is 90.5 %.

• Journal of Electrical Engineering and Technology
• /
• v.11 no.2
• /
• pp.436-444
• /
• 2016

Oil-paper insulation of valve-side windings in converter transformers withstand electrical stresses combining with AC, DC and strong harmonic components. This paper presents the physical mechanisms and experimental researches on partial discharge (PD) of oil-paper insulation at pulsating DC voltage. Theoretical analysis showed that the phase-resolved distributions of PDs generated from different insulated models varied as the increase of the applied voltages following a certain rule. Four artificial insulation defect models were designed to generate PD signals at pulsating DC voltages. Theoretical statements and experimental results show that the PD pulses first appear at the maximum value of the applied pulsating DC voltage, and the resolved PD phase distribution became wider as the applied voltage increased. The PD phase-resolved distributions generated from the different discharge models are also different in the phase-resolved distributions and development progress. It implies that the theoretical analysis is suitable for interpretation of PD at pulsating DC voltage.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
• /
• v.20 no.6
• /
• pp.43-48
• /
• 2006

In this paper, the rectenna converting 2.45[GHz] microwave into DC power is designed and fabricated for wireless power transmission using microwave and the methode for impedance matching and tuning are proposed in order to maximize RF-DC conversion efficiency. The fabricated rectenna can be easily tuned by using a broad open stub and has the RF-DC conversion efficiency up to 59[%] when the 5[dBm] input power is applied. The 2.2[V], 1.5[mW] DC level, in the 1[m] distance between the transmitter and the receiver can be obtained and this value is avaliable in the small power digital system.

• Proceedings of the KIEE Conference
• /
• 2015.07a
• /
• pp.420-421
• /
• 2015

Recently construction of new transmission line is getting harder because of social hostility to transmission tower. Howevere, load is converged in metropolitan area and power plants near this area are old and life of generator will end soon. Therefore, power to supply load in this area should be transmitted from east coast area and southern area. For these reasons, securement of transmission capacity without new transmission line construction is important. In this paper, effect of one circuit AC line change to DC transmission at the same transmission tower on the system available transfer capacity is analyzed.

• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.10 no.9
• /
• pp.2227-2235
• /
• 2009

This paper describes the system configuration and measured performances of a wireless power transmission system which utilizes microwave. The technically final target of this system is to provide DC power to various mobile terminals within limited spaces such as buildings, conference rooms, and so on. The prototype system is built using in-house designed and fabricated circuits such as microwave oscillator, high power amplifier, microstrip patch antenna, low pass filter, and detector/rectifier. The fixed RF power of 29.3dBm at 2.4GHz is produced from the high power amplifier and transmitted through the transmitting antenna, while the received RF power at the receiving antenna is transformed into DC power through the detector/rectifier. The measured change of DC voltage according to the distance between transmitting and receiving antenna is described.

• Journal of Industrial Technology
• /
• v.30 no.A
• /
• pp.69-73
• /
• 2010

In this paper, we designed the RF-DC converter used in wireless power transmission system and studied how to design the RF-DC converter of high conversion efficiency. The RF-DC converter operate at 2.45GHz and the diode is connected with series. The RF-DC converter uses shorted stub for DC loop and matching. We can divide the RF-DC converter circuit into four blocks. The reflection coefficients between the blocks were optimized for the maximum conversion efficiency at 0 dBm input power and $1300{\Omega}$ load impedance. The final design of the RF-DC converter has a 52 percent conversion efficiency.

• Journal of Power Electronics
• /
• v.15 no.4
• /
• pp.886-898
• /
• 2015

The design feasibility of a micro unidirectional DC transmission system based on an input-parallel output-parallel (IPOP) converter is analyzed in this paper. The system consists of two subsystems: an input-parallel output-series (IPOS) subsystem to step up the DC link voltage, and an input-series output-parallel (ISOP) subsystem to step down the output voltage. The two systems are connected through a transmission line. The challenge of the delay caused by the communication in the control system is addressed by introducing a ring communication structure, and its influence on the control system is analyzed to ensure the feasibility and required performance of the converter system under practical circumstances. Simulation and experiment results are presented to verify the effectiveness of the proposed design.

• Journal of the Semiconductor & Display Technology
• /
• v.16 no.2
• /
• pp.85-88
• /
• 2017

In this paper, we have designed and fabricated a RF-DC voltage multiplier for 5.8GHz microwave wireless power transmission. In order to obtain higher voltage, the RF-DC voltage multiplier with 10 diodes (D-10) and the receiver module with an antenna and BPF (Band Pass Filter) was manufactured. The measured and compared results show that the voltages of the proposed one are lower than those of the previous tripler module up to 40cm. However, the voltage of the proposed one with the voltage multiplier is higher than that of the tripler module at the distances of 45cm and 50cm due to the voltage multiplier with 10 diodes.