• Title/Summary/Keyword: voltage sensitivity

Search Result 650, Processing Time 0.028 seconds

Voltage Sensitivity Index Calculation using Dynamic Simulation (동적 시뮬레이션을 이용한 Voltage Sensitivity 지수 계산)

  • Jeong, Sung-Won;Park, In-Deok;Lee, Geun-Joon;Gim, Jae-Hyeon
    • Proceedings of the KIEE Conference
    • /
    • 2007.07a
    • /
    • pp.453-454
    • /
    • 2007
  • This paper proposes the calculation method of voltage sensitivity index using CBEMA power acceptability curves and the voltage curves of the load bus to which momentary events occur. Voltage sensitivity index is represented by areas between two curves. Voltage sensitivity index is a parameter that depicts the ratio of a load disruption. The correlation between the installation cost of compensation devices and the voltage sag index on the bus can be used the validity of compensation.

  • PDF

A Study on the identical basis of static voltage stability analysis methods in power systems (전력 계통 정적 전압 안정도 해석법의 동일 근거에 관한 연구)

  • Moon, Young-Hyun;Kim, Baik;Lee, Eung-Hyuk
    • The Transactions of the Korean Institute of Electrical Engineers
    • /
    • v.45 no.4
    • /
    • pp.457-466
    • /
    • 1996
  • The Voltage stability problem has recently been dealt with in the literature from various points of view. The diverse theories have been established in voltage stability analysis because of the complicates of power systems and diverse phenomena of voltage collapse. Through rigorous mathematical operations, this paper shows that all the major methods used in static voltage stability, i.e - Jacobian method, voltage sensitivity method, real and reactive power loss sensitivity method and energy function method - have an identical background in theory. The results from the test in sample systems have shown the validity of this verification. (author). refs., figs., tabs.

  • PDF

Optimization of Image Quality according to Sensitivity and Tube Voltage in Chest Digital Tomosynthesis (디지털 흉부단층합성검사에서 감도와 관전압 변화에 따른 영상 최적화)

  • Kim, Sang-Hyun
    • Journal of the Korean Society of Radiology
    • /
    • v.12 no.4
    • /
    • pp.541-547
    • /
    • 2018
  • To evaluate the effect of dose and image quality for Chest Digital Tomosynthesis(CDT) using sensitivity and tube voltage(kV). CDT images of the phantom were acquired varying sensitivity 200, 320, 400 according to set tube voltage of 125 kV and 135 kV. The dose and Dose Area Product(DAP) according to change of sensitivity and kV were evaluated and Image quality was evaluated by PSNR, CNR, SNR using Image J. Dose were lowered 14~23% less than sensitivity 200, 125 kV and DAP were lowered 13~26% less than sensitivity 200, 125 kV. PSNR were over 27 dB, which were significant value and CNR, SNR were better as sensitivity value was lower. But there were different statistical significant to each item. CNR and SNR were not statistically significant at sensitivity 320, 135 kV(P>0.05). CDT can improve image quality with lower radiation dose using better than quality and correction power at digital radiography system.

A Distributed Control Method based on Voltage Sensitivity Matrix in DC Microgrids for Improvement of Power Sharing Accuracy and Voltage Regulation Performance (직류 마이크로그리드의 전력 공유 정확도 및 전압 제어 성능 향상을 위한 전압 민감도 행렬 기반의 분산 제어 방법)

  • Lee, Gi-Young;Ko, Byoung-Sun;Lee, Jae-Suk;Kim, Rae-Young
    • The Transactions of the Korean Institute of Power Electronics
    • /
    • v.23 no.5
    • /
    • pp.345-351
    • /
    • 2018
  • A distributed control method is proposed to improve the power sharing performance of bidirectional distributed generators and the voltage regulation performance of a DC bus in a DC microgrid. Voltage sensitivity analysis based on power flow analysis is conducted to analyze the structural characteristics of a DC microgrid. A distributed control method using a voltage sensitivity matrix is proposed on the basis of this analysis. The proposed method uses information received through the communication system and performs the droop gain variation method and voltage shift method without additional PI controllers. This approach achieves improved power sharing and voltage regulation performance without output transient states. The proposed method is implemented through a laboratory-scaled experimental system consisting of two bidirectional distributed generators, namely, a load and a non-dispatchable distributed generator in a four-bus ring-type model. The experimental results show improved power sharing accuracy and voltage regulation performance.

A Positioning Method of Distributed Power System by Considering Characteristics of Droop Control in a DC Microgrid

  • Ko, Byoung-Sun;Lee, Gi-Young;Kim, Sang-Il;Kim, Rae-Young;Cho, Jin-Tae;Kim, Ju-Yong
    • Journal of Electrical Engineering and Technology
    • /
    • v.13 no.2
    • /
    • pp.620-630
    • /
    • 2018
  • In this paper, a positioning method of distributed power system is proposed to minimize the average voltage variation of a DC microgrid through voltage sensitivity analysis. The voltage sensitivity under a droop control depends on the position of the distributed power system. In order to acquire a precise voltage sensitivity under a droop control, we analyzed the power flow by introducing a droop bus with the considerations of the droop characteristics. The results of the positioning method are verified through PSCAD/EMTDC simulation.

A Study on Effective Enhancement of Load Power Factor Using the Load Power Factor Sensitivity of Generation Cost

  • Lee Byung Ha;Kim Jung-Hoon
    • KIEE International Transactions on Power Engineering
    • /
    • v.5A no.3
    • /
    • pp.252-259
    • /
    • 2005
  • Various problems such as increase of power loss and voltage instability may often occur in the case of low load power factor. The demand of reactive power increases continuously with the growth of active power and restructuring of electric power companies makes the comprehensive management of reactive power a troublesome problem, so that the systematic control of load power factor is required. In this paper, the load power factor sensitivity of generation cost is derived and it is used for effectively determining the locations of reactive power compensation devices and for enhancing the load power factor appropriately. In addition, voltage variation penalty cost is introduced and integrated costs including voltage variation penalty cost are used for determining the value of load power factor from the point of view of economic investment and voltage regulation. It is shown through application to a large-scale power system that the load power factor can be enhanced effectively using the load power factor sensitivity and the integrated cost.

A Polysilicon Field Effect Transistor Pressure Sensor of Thin Nitride Membrane Choking Effect of Right After Turn-on for Stress Sensitivity Improvement (스트레스 감도 향상을 위한 턴 온 직후의 조름 효과를 이용한 얇은 질화막 폴리실리콘 전계 효과 트랜지스터 압력센서)

  • Jung, Hanyung;Lee, Junghoon
    • Journal of Sensor Science and Technology
    • /
    • v.23 no.2
    • /
    • pp.114-121
    • /
    • 2014
  • We report a polysilicon active area membrane field effect transistor (PSAFET) pressure sensor for low stress deflection of membrane. The PSAFET was produced in conventional FET semiconductor fabrication and backside wet etching. The PSAFET located at the front side measured pressure change using 300 nm thin-nitride membrane when a membrane was slightly strained by the small deflection of membrane shape from backside with any physical force. The PSAFET showed high sensitivity around threshold voltage, because threshold voltage variation was composed of fractional function form in sensitivity equation of current variation. When gate voltage was biased close to threshold voltage, a fractional function form had infinite value at $V_{tn}$, which increased the current variation of sensitivity. Threshold voltage effect was dominant right after the PSAFET was turned on. Narrow transistor channel established by small current flow was choked because electron could barely cross drain-source electrodes. When gate voltage was far from threshold voltage, threshold voltage effect converged to zero in fractional form of threshold voltage variations and drain current change was mostly determined by mobility changes. As the PSAFET fabrication was compatible with a polysilicon FET in CMOS fabrication, it could be adapted in low pressure sensor and bio molecular sensor.

Voltage Collapse Approximity Indeces Using The Loss Sensitivity (손실 감도를 이용한 전압붕괴 근접도 지표)

  • Kim, Yang-B.;Kim, Kern-J.;Chu, Jin-B.;Kim, Woen-K.;Lee, Sang-J.
    • Proceedings of the KIEE Conference
    • /
    • 1992.07a
    • /
    • pp.218-221
    • /
    • 1992
  • Recent years voltage collapse phenomenon have a great attention to power system engineers. As the system size increases the voltage problem shows a very complicated and the reactive power contol problem becomes more difficult. This paper gives an efficient methods for calculating voltage collapse proximity index based on the reactive power loss sensitivity and real power loss sensitivity. The system voltages are tightly associated with the system reactive power, so the proposed voltage collapse proximity index is very usefull for the system voltage control problems. Numerical examples showed a good and reliable results.

  • PDF

A study on configuration of acoustic package for towed array sonar using design of experiments (실험계획법을 이용한 예인 음탐기용 음향패키지 형상 연구)

  • Lee, JungHyun;Shin, Jeungho;Kwon, Oh-Cho;Kim, Gunchil
    • The Journal of the Acoustical Society of Korea
    • /
    • v.38 no.2
    • /
    • pp.200-206
    • /
    • 2019
  • In this paper, the characteristics of receiving voltage sensitivity about acoustic package in towed array sonar is analyzed through the numerical simulation and design of experiments. Simulation results show that the variation of receiving voltage sensitivity is caused by the structural resonance mode shape on baseline acoustic package. The effect of design parameters of the acoustic package are analyzed through the design of experiments to reduce the deviation of receiving voltage sensitivity. A change of hydrophone shield can thickness (t) is the greatest effect on the deviation of receiving voltage sensitivity. As a result of water tank test, the acoustic package derived from the design of experiments has reduced deviation of receiving voltage sensitivity.

Static Voltage Stability Analysis using Reactive Power Loss Sensitivity (무효전력 손실감도를 이용한 정적 전압 안정도 해석)

  • Kim, Weon-Kyum;Lee, Bok-Yong;Lee, Sang-Cheol
    • Proceedings of the KIEE Conference
    • /
    • 1999.11a
    • /
    • pp.52-55
    • /
    • 1999
  • In recent years, much attention has been paid to the voltage collapse phenomena. There has been reported many cases about the voltage collapse in many countries. These voltage collapse phenomena are known as the event that can occur due to reactive power deficits. This paper proposes an efficient method that can pursue the reactive power loss changes and gives the simple voltage collapse proximity indicator(VCPI) based on the reactive power loss sensitivities using optimal techniques. By comparing reactive power loss sensitivity with active power loss sensitivity, it is also proved that VCPI based on reactive power loss sensitivities is more effective. The developed VCPI is derived from the Jacobian matrix of Load Flow and the computational burden is very low and on-line implementation is possible. The proposed method is applied to a IEEE-14 bus test system and reliable and promising results are obtained.

  • PDF