• The Transactions of the Korean Institute of Electrical Engineers P
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• v.61 no.4
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• pp.220-224
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• 2012

The analysis on the bus bar effect is conducted to develop a cost effective 24kV/2,000A switchgear. The temperature enclosures and bus bars could rise due to several heat sources such as eddy current losses and copper losses. Therefore, a study on the characteristics of the electric field intensity and electromagnetic loss according to the bus bar size in a bus bar compartment is essential to design a electrically reliable high voltage switchgear. It is investigated that the electromagnetic influence to the temperature rising and the dielectric stability according to various bus bar sizes by using finite element method(FEM). The electric field intensity and electromagnetic loss according to various bus bar sizes are calculated to design a reliable and a high voltage switchgear. As results, it is found that the electromagnetic loss and the dielectric stability of bus bar could be determined by a bus bar size. It means that a cost effective 24kV/2,000A high voltage switchgear could be developed by selecting the proper size of a bus bar. Also, it is recognized that the electromagnetic characteristics according to various bus bar sizes in order to design an electrically stable high voltage switchgear when the enclosure size is determined as a fixed value. Futhermore, studies on the various nominal voltage class and bus bar sizes will be conducted to develop a cost effective high voltage switchgear.

• Proceedings of the KIPE Conference
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• 2014.11a
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• pp.66-67
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• 2014

Stabilization of the DC bus voltage is an important task in DC-AC microgrid system with renewable energy source such as solar system. A battery energy storage system (BESS) has become a general solution to stabilize the DC-bus voltage in DC-AC microgrid. This paper develops the analog BESS controller which requires neither computation nor dc-bus voltage measurement, so that the system can be implemented simply and easily. Even though others methods can stabilize and control the DC-bus voltage, it has complicated structure in control and low adaptive capability. The proposed topology is simple but is able to compensate the solar source variation and stabilize the DC-bus voltage under any loads and distributed generation (DG) conditions. In addition, the design of analog controller is presented to obtain a robust system. In order to verify the effectiveness of the proposed control strategy, simulation is carried out by using PSIM software.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.61 no.11
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• pp.1617-1624
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• 2012

A DC power system has many loads with varied functions. Also, there may be large pulsed loads with short duty ratios which can affect the normal operation of other loads. In this paper, Voltage Bus Conditioner(VBC) without any current sensors is proposed to damp the bus voltage transients by parallel pulsed loads. The proposed control approach requires only one voltage sensor and carries out both the functions of damping the bus voltage transients and maintaining the level of energy stored. The proposed control technique has been implemented on a TMS320F2812 Digital Signal Processor(DSP). Simulated results by a Matlab Simulink and experimental results are presented which verify the control principles and demonstrate the practicalty of the approach.

• The Transactions of the Korean Institute of Electrical Engineers P
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• v.55 no.1
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• pp.47-53
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• 2006

A Voltage Bus Conditioner (VBC) is used to mitigate the voltage transients on a common power distribution bus. The VBC described here utilises inductive storage and unlike its counter part with capacitive storage, it can employ the entire stored energy towards transients' mitigation. The performances of adaptive duty ratio control and sliding mode control have been compared. The simulation results (with the package SABER) indicate that the sliding mode control results in the shortest and the smallest bus voltage excursions.

• The Transactions of the Korean Institute of Electrical Engineers P
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• v.60 no.1
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• pp.13-18
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• 2011

More and all-electric aircraft (AEA) carry many loads with varied functions. In particular, there may be large pulsed loads with short duty ratios which can affect the normal operation of other loads. In this paper, a converter with spilt capacitors and an improved adaptive controller is used as the Voltage Bus Conditioner (VBC) with the reduced capacitive storage to mitigate the voltage transients on the bus. The proposed converter allows the smaller capacitive storage. Also, the proposed controller has the advantage of requiring only one sensor and performing both the functions of mitigating the voltage bus transients and maintaining the level of energy stored. Experimental results are presented which verify the control principles and demonstrate the practicality of the approach.

• Proceedings of the KIEE Conference
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• 1994.11a
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• pp.45-47
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• 1994

The simulation of reactive power compensation in 5-bus and 25-bus system was conducted using transmission-line loss system identification method. Sensitivities of maximum load-power with respect to reactive power compensation was identified by the simulation. With sufficient reactive power compensation at the first voltage-collapsing load-bus, the first voltage collapse could be prevented until the next voltage-collapsing load-bus lost its voltage stability. And the total compensated reactive power at the first voltage-collapsing bus means reactive power margin of voltage collapse or distance to voltage collapse. This quantity can be useful for determining the size of compensating devices or the site to compensate.

• Journal of the Korean Institute of Telematics and Electronics C
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• v.36C no.7
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• pp.10-16
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• 1999

This paper describes a low voltage swing bus driver using FCSR(Feedback Control Swing voltage Reduction) which can control bus swing voltage within a few hundred of mV. It is proposed to reduce power consumption in On-chip interface, especially for MDL(Merged DRAM Logic) architecture wihich has wide and large capacitance bus. FCSR operates on differential signal dual-line bus and on precharged bus with block controlling fuction. We modeled driver and bus to scale driver size automatically when bus environment is variant. We also modeled coupling capacitance noise(crosstalk) of neighborhood lines which operate on odd mode with parallel current source to analysis crosstalk effect in the victim-line according as voltage transition in the aggressor-line and environment in the victim-line. We built a test chip which was designed to swing 600mV in bus, shows 70Mhz operation at 3.3V, using Hyundai 0.8um CMOS technology. FCSR operate with 250Mhz at 3.3V by Hspice simulation.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.26 no.3
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• pp.216-220
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• 2013

The rated voltage has been rising in order to minimize the losses in power transmission. The high voltage electric machines should be minimized due to the constraints of space. Therefore, the temperature of high voltage electric apparatuses easily exceeds the temperature limits. In this paper, it is investigated that how to minimize the internal temperature rising of a high voltage switchgear by adjusting the arrangement of bus bars. High voltage switchgears consist of a circuit breaker, a CT, a PT, a earthing switches, bus bars, and so on. It is very difficult to estimate the electromagnetic properties of a high voltage switchgear due to these various environments and structures. In this paper, analyses are focused on the electromagnetic characteristics of bus bars according to the arrangement method and the enclosures to simplify the electromagnetic characteristics of a switchgear. It is found that the characteristics of electric field intensity and electromagnetic losses in bus bars are influenced by the arrangement method of bus bars. However, it is confirmed that the electromagnetic characteristics of enclosures are not affected by the arrangement of bus bars. In this paper, the arrangement methods of bus bars to minimize the electric field intensity and electromagnetic losses are suggested. It is expected that the research results are helpful to design and develop an electrically reliable high voltage switchgear.

• The Transactions of the Korean Institute of Electrical Engineers P
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• v.56 no.2
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• pp.90-98
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• 2007

More and All-Electric Aircraft (AEA) carry many loads with varied functions. In particular, there may be large pulsed loads with short duty ratio, which can affect the normal operation of other loads. In this paper, a bi-directional converter with inductive storage is used as a voltage bus conditioner (VBC) to mitigate voltage transients on the bus. In addition, the constant frequency hysteresis control technique for a VBC is presented. A simple and fast prediction of the hysteresis band-width is implemented by the phase-lock loop control, keeping constant switching frequency. This technique offers the excellent dynamic response in load or parameter variation. The control performance is illustrated by simulated results with the SABER package, The proposed hysteresis control results in the shortest and the smallest excursions.

• The Transactions of the Korean Institute of Electrical Engineers A
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• v.55 no.12
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• pp.505-513
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• 2006

One of the major reasons for recent blackout, like August 14, 2003 blackout in the US and Canada has been insufficient voltage/reactive power support. For the stable reactive power management, a new approach for the voltage monitoring and control structure is required in the market environment. This paper proposes the effective localized-voltage control scheme using the information from pilot buses at each zone. In this paper, the steady state voltage monitoring and control (SSVMC) is adopted and illustrated for the voltage control scheme during steady state because it is thought as the systemic algorithm to explain voltage profile phenomenon before and after contingencies. And the concept of electrical distance is applied to simultaneously achieve both clustering the voltage control zone, and selecting the pilot bus as the representative node at each control zone. Applying SSVMC based on the structure with clustering and pilot bus enables system operators to monitor and understand the system condition much more easily, to monitor and control the voltage in real-time more manageably, and to respond quickly to a disturbance. The proposed voltage control scheme has been tested on the IEEE 14-bus system with the numerical analysis to examine the system reliability and structure efficiency.