• Journal of Chest Surgery
• /
• v.35 no.8
• /
• pp.605-607
• /
• 2002

Harmonic Scalpel(Ethicon Endo-Surgery, Cincinnati, OH) has many advantages including no muscular stimulation, low heat, less smoke, easy hemostasis using ultrasound and good operation field. In patient with constrictive pericarditis, Harmonic Scalpel was beneficial during pericardiectomy.

• Journal of Power Electronics
• /
• v.18 no.5
• /
• pp.1513-1522
• /
• 2018

This paper proposes a new islanding detection method for inverter-based distributed generators by continuously injecting a negligible amount of 2nd order harmonic current. The proposed method adopts a proportional resonant (PR) controller for the output current control of the inverter, and a PR filter to extract the 2nd order harmonic voltage at the point of common coupling (PCC). The islanding state can be detected by measuring the magnitude ratio of the 2nd order harmonic voltage to the fundamental voltage at the PCC by injecting a 2nd order harmonic current with a 0.8% magnitude. The proposed method provides accurate and fast detection under grid voltage unbalance and load unbalance. The operation of the proposed method has been verified through simulations and experiments with a 5kW hardware set-up, considering the islanding test circuit suggested in UL1741.

• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.9 no.1
• /
• pp.59-63
• /
• 2008

This paper analyze the operating characteristic of RCB due to the synthesize harmonic current. The RCB of rated sensitivity electric current with 30[mA] test to operating characteristic by synthesize harmonic current and it analyzed the tripping operation due to a harmonic current. The test result, the operating current of RCB changed by synthesize harmonic current.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
• /
• v.27 no.3
• /
• pp.43-49
• /
• 2013

Recently harmonics flowing into power system is increasing as the usage of semiconductor equipments and switching mode power equipments are increasing. Harmonics cause problems such as heat increasing and reduction in capacity of transformers, especially the harmonics flowing into a distribution transformer can lead to the lifetime reduction of transformer. In this paper, we are about to develop a device that can monitor harmonics in real-time as it is affixed to a distribution transformer. Unlike the existing expensive harmonic analysis device, a new harmonic analysis algorithm is proposed in order to implement low-cost equipment. The real-time harmonic analysis algorithm proposed in this paper allows implementation on low performance microcontrollers, thus it can monitor the harmonic in real-time as it is individually affixed to the transformer. Therefore, it would improve the reliability of the transformer and stable power system operation would be possible as it can prevent the transformer accidents in advance.

• Journal of Electrical Engineering and Technology
• /
• v.13 no.5
• /
• pp.1956-1964
• /
• 2018

Since the stator winding of High-Speed Permanent Magnet Generator (HSPMG) has few winding turns and low inductance value, it is more prone to be influenced by harmonic current. Moreover, the operation efficiency and the torque stability of HSPMG will be greatly influenced by harmonic current. Taking a 117 kW, 60 000 rpm HSPMG as an example, in order to analyze the effects of harmonic current on HSPMG in this paper, the 2-D finite element electromagnetic field model of the generator was established and the correctness of the model was verified by testing the generator prototype. Based on the model, the losses and torque of the generator under different frequency harmonic current were studied. The change rules of the losses and torque were found out. Based on the analysis of the influence of the harmonic phase angle on torque ripple, it is found that the torque ripple could be weakened through changing the harmonic phase angle. Through the analysis of eddy current density in rotor, the change mechanism of the rotor eddy current loss was revealed. These conclusions can contribute to reduce harmonic loss, prevent demagnetization fault and optimize torque ripple of HSPMG used in distributed power supply system.

• Proceedings of the KIEE Conference
• /
• 2007.07a
• /
• pp.152-153
• /
• 2007

industrial site has led to a growing concern for harmonic distortion and the resulting impacts on system equipment and operation. Harmonic current is generated by the operation of non-linear load, it means that voltage and current waveforms exhibit a non-linear relationship. Harmonics cause increase losses in the customer and utility power system components. This paper describes application of instantaneous active and reactive theory for the compensation of harmonic currents in three-phase non-linear load.

• Proceedings of the Korean Institute of IIIuminating and Electrical Installation Engineers Conference
• /
• 2006.05a
• /
• pp.43-48
• /
• 2006

This paper presents a scheme on the characteristics of induction motor under the combination of linear & non-linear loads at the three phase 4-wire power distribution system. Under the combination operation of single & three phase load, voltage unbalance will be generated and current unbalance will be more severe by the dropped voltage quality. All power electronic converters used in different types of electronic systems can increase harmonic disturbances by injecting harmonic currents directly into the feeder grid of three phase 4-wire. Harmonic current may cause torque to decrease. Moors may also overheat or become noisy and torque oscillation in the rotor can lead to mechanical resonance and vibration.

• Journal of Power Electronics
• /
• v.14 no.1
• /
• pp.92-104
• /
• 2014

To insure stable operation and eliminate twice torque ripple, a topology for a six phase permanent magnet synchronous generator (SP-PMSG) with a neutral point connected together was analyzed in this paper. By adopting an extended transformation matrix, the mathematic model of the space vector control was established. The voltage and torque equations were deduced while considering the third harmonic flux and inductance. In addition, the suppression third harmonic method and the closed loop control strategy were proposed. A comparison analysis indicates that the cooper loss minimum method and the current magnitude minimum method can meet different application requirements. The voltage compensation amount for each of the methods was deduced which also takes into account the third harmonic effect. A simulation and experimental result comparison validates the consistency through theoretical derivation. It can be seen that all of the two control strategies can meet the requirements of post-fault.

• Proceedings of the KIEE Conference
• /
• 1994.07b
• /
• pp.1577-1579
• /
• 1994

200-MW pulse modulators(total 11units) for the PLS linac employ the SCR phase control circuit. It controls 3-phase AC line voltage for the high-voltage DC power supply (DCPS, maximum of 25kVDC, 4.2A) which charges the pulse forming network(PFN). The PFN delivers 400kV, 500A, ESW $7.5{\mu}s$ pulse power to the 80-MW klystron amplifier tube. The SCR regulates 3-phase AC power and feeds to the high voltage transformer. Two different types of the transformer configurations namely ${\Delta}-{\Delta}$ and ${\Delta}-Y$, are alternatively installed to 11 modulator units for the suppression of harmonic noises. RC filters and reactors are also installed. Currently, approximately 110-kW of average AC power per unit is consumed at the normal operation level of the modulator with 30pps. This paper presents the operational characteristics of the high power pulse modulator, especially the experimental results of the AC line harmonic components generated by the operation of the high power pulse modulator to suppress the switching noises from the SCR and rectifying diode arrays.

• Proceedings of the Korean Institute of IIIuminating and Electrical Installation Engineers Conference
• /
• 2009.05a
• /
• pp.297-300
• /
• 2009

Recently, TTX(Tilting Train eXpress), EMU (Electric Multiple Unit) has operated test. Presently, electric problems(harmonic, voltage variation etc) of TTX are studying briskly. Henceforth, electrical harmonic study of TTX will operate on the rail actually is needed. In this paper, we detected electrical harmonic of operating TTX. In addition to we analyzed and estimated electrical harmonic regarding TTX's coasting, acceleration and braking state.