• Proceedings of the KIEE Conference
• /
• 2006.07a
• /
• pp.266-267
• /
• 2006

A coupling capacitor voltage transformer (CCVT) is used in extra high voltage and ultra high voltage transmission systems to obtain the standard low voltage signal for protection and measurement. To obtain the high accuracy at the power system frequency, a tuning reactor is connected between a capacitor and a voltage transformer (VT). Thus, no distortion of the secondary voltage is generated when no fault occurs. However, when a fault occurs, the secondary voltage of the CCVT has some errors due to the transient components resulting from the fault. This paper proposes an algorithm for compensating the secondary voltage of the CCVT in the time domain. With the values of the secondary voltage of the CCVT, the secondary and the primary currents are obtained; then the voltage across the capacitor and the tuning reactoris calculated and then added to the measured secondary voltage. The proposed algorithm includes the effect of the non-linear characteristic of the VT and the influence of the ferro-resonance suppression circuit. Test results indicate that the algorithm can successfully compensate the distorted secondary voltage of the CCVT irrespective of the fault distance, the fault inception angle and the fault impedance.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
• /
• v.22 no.8
• /
• pp.784-789
• /
• 2011

In this paper, a tunable integrated transmitter leakage canceller based on an autotransformer for ultra-high-frequency (UHF) RFID readers is presented. The proposed TX leakage canceller consists of an autotransformer, a digital tuning capacitor, a voltage controlled tuning resistor, and a compensating amplifier, and it is designed using 0.13 ${\mu}m$ 1-poly 6-metal RF CMOS process. The simulation results show that the proposed structure has over 55 dB rejection characteristic between a transmitter and a receiver and a 2.5 dB of the RX insertion loss. The TX leakage canceller can be digitally tuned from 825 MHz to 985 MHz with the tuning capacitor and it can be fully integrated.

• Proceedings of the KSR Conference
• /
• 2010.06a
• /
• pp.514-520
• /
• 2010

This paper is about control algorithms that bi-direction DC-DC Converter using Super Capacitor and regenerative power from DC feeding system in train. In order to take advantage of regenerative energy efficient, charge and discharge level value of energy storage system serve as an important factor. Respect to output fluctuations of the substation and catenary voltage changing, we offers Charge-Discharge Auto Level Tuning Algorithms to improve system following of Energy Storage System.

• The Transactions of the Korean Institute of Power Electronics
• /
• v.19 no.3
• /
• pp.290-296
• /
• 2014

This paper presents a design strategy for the control of the Z-source inverter (ZSI). For the Z-network capacitor voltage control, the average current model is derived to describe the dynamics of the voltage control and the controller outputs the average current command for the capacitor. Z-network inductor current reference is derived from the average current model of the Z-network capacitor. The inner current control loop outputs the average voltage command for the Z-network inductor and the shoot-through duty ratio of the ZSI is calculated from the output using the average voltage model of the Z-network inductor. The gain values of the current and voltage controllers are directly obtained by the Z-network parameters and desired bandwidth of each controller without a gain tuning process.

• Proceedings of the KIEE Conference
• /
• 2002.06a
• /
• pp.60-63
• /
• 2002

This paper presents a control approach for designing a self tuning fuzzy controller for SVC system, A SVC constructed by a Fixed Capacitor and a Thyristor Controlled Reactor is designed and implemented to improve the damping of a synchronous generator, as well as controlling the system voltage, The proposed parameter self tuning algorithm of fuzzy controller is based on the steepest decent method using two direction vectors which make error between inference values of fuzzy controller and output values of the specially selected PSS reduce steepestly, The related simulation results show that the proposed fuzzy controller is more powerful than the conventional ones.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
• /
• 2003.11a
• /
• pp.624-629
• /
• 2003

In this paper, broadband shunt technique for increasing transmission loss is experimentally investigated. Piezoelectric shunt damping is studied using resonant shunt circuit and negative capacitor shunt circuit. A resonant shunt circuit is implemented by using a resistor and inductor. Negative Capacitor shunt damping is similar in nature to resonant shunt damping techniques, as a single piezoelectric material is used to dampen multi-mode. Performance of both methods is experimentally studied for noise reduction. This is based upon SAE J1400 test method and a transmission loss measurement system is provided for it. This paper will present the test setup fer transmission loss measurement and the tuning procedure of shunt circuits. Finally the results of sound transmission tests will be shown.

• Journal of Sensor Science and Technology
• /
• v.6 no.2
• /
• pp.115-122
• /
• 1997

In this paper, on-chp atomatic tuning circuit, using proposed integration level approximation technique, is designed to tuning of the variation of RC time-constant due to aging or temperature variation, etc. This circuit reduces the error, the difference between code values and real outputs of integrator, which is drawback of presented dual-slope tuning circuit and eliminates modulations of processing signals in integrated circuit due to fixed tuning codes during ordinary operation. This system is made up of simple integrator, A/D converter and digital control circuit and all capacitors are replaced by programed capacitor arrays in this system. This tuning circuit with 4 bit resolution achieves $-9.74{\sim}+9.68%$ of RC time constant error for 50% resistance variation.

• The Transactions of The Korean Institute of Electrical Engineers
• /
• v.57 no.6
• /
• pp.909-914
• /
• 2008

A coupling capacitor voltage transformer(CCVT) is used in an extra or ultra high voltage system to obtain the standard low voltage signal for protection. To avoid the phase angle error between the primary and secondary voltages, a tuning reactor is connected between a capacitor and a voltage transformer. The inductance of the reactor is designed based on the power system frequency. If a fault occurs on the power system, the secondary voltage of the CCVT contains some errors due to a dc offset component and harmonic components resulting from the fault. The errors become severe in the case of a close-in fault. This paper proposes an algorithm for compensating the secondary voltage of a CCVT in the time-domain. From the measured secondary voltage of the CCVT, the secondary and primary currents are obtained; then the voltage across the capacitor and the inductor is calculated and then added to the measured secondary voltage to obtain the correct primary voltage. Test results indicate that the proposed algorithm can compensate the distorted secondary voltage of the CCVT irrespective of the fault distance, the fault inception angle, and the burden of the CCVT.

• Journal of IKEEE
• /
• v.22 no.3
• /
• pp.780-785
• /
• 2018

In this work, We investigated the frequency-dependent capacitance tunability of a metal-ferroelectric-metal variable capacitor fabricated using ALD $HfO_2$ ferroelectric material. The capacitance of the MFM capacitor could be tuned as a function of the bias voltage, up to the microwave frequency range. We observed a capacitance tuning range of ~3 % up to 2.5 GHz, proving the feasibility of the use of ALD $HfO_2$ in the microwave frequency band.

• Journal of the Korean Institute of Telematics and Electronics
• /
• v.5 no.3
• /
• pp.9-24
• /
• 1968

This report is concerned with the optimum design of hyper-aprupt p-n junctiea silion diode and fabriction of this diode usable for electrical tuning application. Impurity profile in the junction was assumed to clean exponential function. With this assunntion, an optimum criterion for designing standard AM radio tuning capacitor was derived. In the diffusion process, after aluminum and antimony as impurties were deposited in vacuum on a P-type silicon wafer, the diffusion was followed by loading the wafer into the high temperature furnace.