• Title/Summary/Keyword: Advanced frequency estimation

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Advanced Frequency Estimation Technique using Gain Compensation (이득 보상에 의한 개선된 주파수 추정 알고리즘)

  • Park, Chul-Won
    • The Transactions of the Korean Institute of Electrical Engineers P
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    • v.59 no.2
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    • pp.173-178
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    • 2010
  • Frequency is an important operating parameter of a power system. Due to the sudden change in generation and loads or faults in power system, the frequency is supposed to deviate from its nominal value. It is essential that the frequency of a power system be maintained very close to its nominal frequency. And monitoring and an accurate estimation of the power frequency by timing synchronized signal provided by FDR is essential to optimum operation and prevention for wide area blackout. As most conventional frequency estimation schemes are based on DFT filter, it has been pointed out that the gain error by change in magnitude could cause the defects when the power frequency is deviated from nominal value. In this paper, an advanced frequency estimation scheme using gain compensation for fault disturbance recorders (FDR) is presented. The proposed scheme can reduce the gain error caused when the power frequency is deviated from nominal value. Various simulation using both the data from EMTP package and user's defined arbitrary signals are performed to demonstrate the effectiveness of the proposed scheme. The simulation results show that the proposed scheme can provide better accuracy and higher robustness to harmonics and noise under both steady state tests and dynamic conditions.

Development of Dynamic Frequency Monitoring Software for Wide-Area Protection Relaying Intelligence (광역 보호계전 지능화를 위한 동적 주파수 모니터링 S/W 개발)

  • Kim, Yoon-Sang;Park, Chul-Won
    • The Transactions of the Korean Institute of Electrical Engineers P
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    • v.61 no.4
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    • pp.174-179
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    • 2012
  • The social and economic level of damages might be highly increased in the case of wide-area black-outages, because of heavy dependence of electricity. Therefore, the development of a wide-area protection relay intelligence techniques is required to prevent massive power outages and minimize the impact strength at failure. The frequency monitoring and prediction for wide-area protection relaying intelligence has been considered as an important technology. In this paper, a network-based frequency monitoring system developed for wide-area protection relay intelligence is presented. In addition, conventional techniques for frequency estimation are compared, and a method for advanced frequency estimation and measurement to improve the precision is proposed. Finally, an integrated monitoring system called K-FNET(Korea-Frequency Monitoring Network) is implemented based on the GPS and various energy monitoring cases are studied.

Performance Evaluation of Advanced Frequency Estimation Technique using 765kV Modeling Data (765kV 모델링 데이터에 의한 개선된 주파수 추정기법의 성능 평가)

  • Park, Chul-Won
    • The Transactions of the Korean Institute of Electrical Engineers P
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    • v.59 no.3
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    • pp.253-257
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    • 2010
  • The frequency is an important operation parameter for the control, protection, and stability of a power system. The frequency as a key index of power quality can be indicative of system abnormal conditions and disturbances. Due to the sudden change in generation and loads or faults in power system, the frequency is supposed to deviate from its nominal value. It is essential that the frequency must be maintained very close to its nominal frequency. An accurate monitoring of the power frequency is essential to optimal operation and prevention for wide area blackout. As most conventional frequency estimation schemes are based on DFT filter, it has been pointed out that the gain error could cause defects when the frequency is deviated from nominal value. This paper presents an advanced frequency estimation technique using gain compensation to improve the performance of DFT filter based techniques. To evaluate performance of the proposed algorithm, the 765kV T/L system in Korea is simulated by EMTP-RV software. The proposed technique can reduce the gain error caused when the power system frequency deviates from nominal value.

Study on Advanced Frequency Estimation Technique using Gain Compensation

  • Park, Chul-Won;Shin, Dong-Kwang;Kim, Chul-Hwan;Kim, Hak-Man;Kim, Yoon-Sang
    • Journal of Electrical Engineering and Technology
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    • v.6 no.4
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    • pp.439-446
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    • 2011
  • Frequency is an important operating parameter for the protection, control, and stability of a power system. Thus, it must be maintained very close to its nominal frequency. Due to the sudden change in generation and loads or faults in a power system, however, frequency deviates from its nominal value. An accurate monitoring of the power frequency is essential for optimum operation and prevention of wide area blackout. Most conventional frequency estimation schemes are based on the DFT filter. In these schemes, the gain error could cause defects when the frequency deviates from the nominal value. We present an advanced frequency estimation technique using gain compensation to enhance the DFT filter-based technique. The proposed technique can reduce the gain error caused when the frequency deviates from the nominal value. Simulation studies are performed using both the data from EMTP-RV software and the user-defined arbitrary signals to demonstrate the effectiveness of the proposed algorithm. Results show that the proposed algorithm achieves good performance under both steady state tests and dynamic conditions.

Damage Estimation of Structures Incorporating Structural Identification (동특성 추정을 이용한 구조물의 손상도 추정)

  • Yun, Chung-Bang;Lee, Hyeong-Jin;Kim, Doo-Ki
    • Proceedings of the Computational Structural Engineering Institute Conference
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    • 1995.04a
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    • pp.136-143
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    • 1995
  • The problem of the structural identification becomes important, particularly with relation to the rapid increase of the number of the damaged or deteriorated structures, such as highway bridges, buildings, and industrial facilities. This paper summarizes the recent studies related to those problems by the present authors. The system identfication methods are generally classified as the time domain and the frequency domain methods. As time doamin methods, the sequential algorithms such as the extended Kalman filter and the sequential prediction error method are studied. Several techniques for improving the convergences are incorporated. As frequency domain methods, a new frequency response function estimator is introduced. For damage estimation of existing structures, the modal perturbation and the sensitivity matrix methods are studied. From the example analysis, it has been found that the combined utilization of the measurement data for the static response and the dynamic (modal) properties are very effictive for the damage estimation.

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A Fast ICI Suppression Algorithm with Adaptive Channel Estimation for the LTE-Advanced Uplink System (LTE-Advanced 상향 링크 시스템을 위한 적응적 채널 추정을 통한 고속 ICI 제거 방법 연구)

  • Jeong, Hae-Seong;Ryu, Heung-Gyoon
    • The Journal of Korean Institute of Electromagnetic Engineering and Science
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    • v.22 no.1
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    • pp.30-37
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    • 2011
  • In this paper, we propose a fast ICI suppression algorithm with adaptive channel estimation for the LTE-Advanced uplink system. In order to effectively remove phase noise and carrier frequency offset at time varying channel, we use the comb type pilot. The purpose is to improve performance by reducing computational complexity than conventional PNFS(Phase Noise & Frequency offset Suppression) algorithm. We reduce computational complexity by decreasing overlapping computation or unnecessary computation at conventional PNFS algorithm. Also, we propose an effective channel estimation method. We estimate and compensate multipath channel through the proposed adaptive channel estimation method. The BER performance of the proposed method is better about 0.5 dB than the conventional method at the Vehicular A channel.

A Joint Frequency Offset Measurement Using Inversely Repeated Training Symbol and Cyclic Prefix (훈련심볼의 위상 반전과 전치순환을 이용한 주파수 오프셋의 계산방법)

  • Kim, Jun-Woo;Park, Youn-Ok;Kim, Whan-Woo
    • The Journal of Korean Institute of Communications and Information Sciences
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    • v.36 no.7A
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    • pp.627-634
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    • 2011
  • In this paper, a new frequency offset estimation method in OFDM system is suggested. To measure fractional part of frequency offset, the repetition feature of cyclic prefix and that of training sequence is adopted. Both method shows relatively large frequency offset estimation error under low SNR circumstances, but this error can be greatly reduced by joint measurement of cyclic prefix and inversely repeated training symbol such as primary advanced preamble (PA-preamble) of IEEE 802.16m IMT-Advanced WiMax system. In this paper, the performance of suggested frequency offset estimation method is verified in IEEE 802.16m IMT Advanced WiMax system, using its PA-preamble and cyclic prefixes of A-preambles.

Minimum Statistics-Based Noise Power Estimation for Parametric Image Restoration

  • Yoo, Yoonjong;Shin, Jeongho;Paik, Joonki
    • IEIE Transactions on Smart Processing and Computing
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    • v.3 no.2
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    • pp.41-51
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    • 2014
  • This paper describes a method to estimate the noise power using the minimum statistics approach, which was originally proposed for audio processing. The proposed minimum statistics-based method separates a noisy image into multiple frequency bands using the three-level discrete wavelet transform. By assuming that the output of the high-pass filter contains both signal detail and noise, the proposed algorithm extracts the region of pure noise from the high frequency band using an appropriate threshold. The region of pure noise, which is free from the signal detail part and the DC component, is well suited for minimum statistics condition, where the noise power can be extracted easily. The proposed algorithm reduces the computational load significantly through the use of a simple processing architecture without iteration with an estimation accuracy greater than 90% for strong noise at 0 to 40dB SNR of the input image. Furthermore, the well restored image can be obtained using the estimated noise power information in parametric image restoration algorithms, such as the classical parametric Wiener or ForWaRD image restoration filters. The experimental results show that the proposed algorithm can estimate the noise power accurately, and is particularly suitable for fast, low-cost image restoration or enhancement applications.

Performance of SC-FDE System in UWB Communications with Imperfect Channel Estimation

  • Wang, Yue;Dong, Xiaodai
    • Journal of Communications and Networks
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    • v.9 no.4
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    • pp.466-472
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    • 2007
  • Single carrier block transmission with frequency domain equalization(SC-FDE) has been shown to be a promising candidate in ultra-wideband(UWB) communications. In this paper, we analyze the performance of SC-FDE over UWB communications with channel estimation error. The probability density functions of the frequency domain minimum mean-squared error(MMSE) equalizer taps are derived in closed form. The error probabilities of single carrier block transmission with frequency domain MMSE equalization under imperfect channel estimation are presented and evaluated numerically. Compared with the simulation results, our semi-analytical analysis yields fairly accurate bit error rate performance, thus validating the use of the Gaussian approximation method in the performance analysis of the SC-FDE system with channel estimation error.

MASS ESTIMATION OF IMPACTING OBJECTS AGAINST A STRUCTURE USING AN ARTIFICIAL NEURAL NETWORK WITHOUT CONSIDERATION OF BACKGROUND NOISE

  • Shin, Sung-Hwan;Park, Jin-Ho;Yoon, Doo-Byung;Choi, Young-Chul
    • Nuclear Engineering and Technology
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    • v.43 no.4
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    • pp.343-354
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    • 2011
  • It is critically important to identify unexpected loose parts in a nuclear reactor pressure vessel, since they may collide with and cause damage to internal structures. Mass estimation can provide key information regarding the kind as well as the location of loose parts. This study proposes a mass estimation method based on an artificial neural network (ANN), which can overcome several unresolved issues involved in other conventional methods. In the ANN model, input parameters are the discrete cosine transform (DCT) coefficients of the auto-power spectrum density (APSD) of the measured impact acceleration signal. The performance of the proposed method is then evaluated through application to a large-sized plate and a 1/8-scaled mockup of a reactor pressure vessel. The results are compared with those obtained using a conventional method, the frequency ratio (FR) method. It is shown that the proposed method is capable of estimating the impact mass with 30% lower relative error than the FR method, thus improving the estimation performance.