• Title/Summary/Keyword: Voltage sag detection

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An Improvement in Synchronously Rotating Reference Frame-Based Voltage Sag Detection under Distorted Grid Voltages

  • Sillapawicharn, Yutthachai;Kumsuwan, Yuttana
    • Journal of Electrical Engineering and Technology
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    • v.8 no.6
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    • pp.1283-1295
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    • 2013
  • This study proposed an improvement in synchronously rotating reference frame-based voltage sag detection under distorted grid voltages. In the past, the conventional synchronously rotating reference frame (CSRRF)-based voltage sag detection was generally used in the voltage sag compensation applications. Its disadvantage is a long delay of detection time. The modified synchronously rotating reference frame (MSRRF)-based voltage sag detection is able to detect the voltage sag with only a short delay in detection time. However, its operation under distorted grid voltage conditions is unavailable. This paper proposed the improvement of modified synchronously rotating reference frame (IMSRRF)-based voltage sag detection for use in distorted grid voltages with very fast operation of voltage sag detection. The operation of the proposed voltage sag detections is investigated via simulations and experimentations to verify the performance of the IMSRRF-based voltage sag detection.

Three-Phase PWM-Switched Autotransformer Voltage-Sag Compensator Based on Phase Angle Analysis

  • Mansor, Muhamad;Rahim, Nasrudin Abd.
    • Journal of Power Electronics
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    • v.11 no.6
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    • pp.897-903
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    • 2011
  • Many voltage sag compensators have been introduced, including the traditional dynamic voltage restorer (DVR), which requires an energy storage device but is inadequate for compensating deep and long-duration voltage sags. The AC-AC sag compensators introduced next do not require a storage device and they are capable of compensating voltage sags. This type of compensator needs an AC-AC converter to regulate the output voltage. Presented in this paper is a three-phase PWM-switched autotransformer voltage sag compensator based on an AC-AC converter that uses a proposed detection technique and PWM voltage control as a controller. Its effectiveness and capability in instantly detecting and compensating voltage sags were verified via MATLAB/Simulink simulations and further investigated through a laboratory prototype developed with a TMS320F2812 DSP as the main controller.

Implementation of a Non-Linear Adaptive Filter Based Sag Detection Method for Dynamic Voltage Restorers under Unbalanced Fault Conditions

  • Cuma, M. Ugras;Teke, Ahmet;Meral, M. Emin;Bayindir, K. Cagatay;Tumay, Mehmet
    • Journal of Power Electronics
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    • v.13 no.2
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    • pp.304-312
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    • 2013
  • The most common power quality problems in distribution systems are related to unbalanced voltage sags. Voltage sags must be detected quickly and corrected in a minimum amount of time. One of the most widely used methods for sag detection is based on the d-q transformation. This method has the disadvantage of missing the detection of unbalanced faults, because this method uses a voltage sag level signal obtained from the average of 3 phases for sag detection. In this paper, an adaptive filter sag detection method is proposed for Dynamic Voltage Restorers (DVR) under unbalanced fault conditions. The proposed DVR controller is able to detect balanced, unbalanced and single phase voltage sags. A novel reference voltage generation method is also presented. To validate the proposed control methods, a 3-phase DSP controlling a DVR prototype with a power rating of 1.5-kVA has been developed. Finally, experimental results are presented to verify the performance of the proposed control methods.

Voltage Sag Detection Algorithm for Instantaneous Voltage Sag Corrector

  • Lee, Sang-Hoon;Choi, Jae-Ho
    • Journal of Power Electronics
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    • v.2 no.3
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    • pp.162-170
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    • 2002
  • Voltage sag detection algorithm for voltage sag corrector is proposed in this paper. To quantify the standard of voltage unbalance under the faulted conditions, the 3-phase unbalanced voltages are decomposed into two balanced 3-phase symmetrical components of the positive and negative sequence voltages, which is defined by the magnitude factor (MF) and unbalance factor (UF). It is analyzed that MWF and UF values are given as the dc constant values even though under the voltage unbalance condition. This paper also proposes the control scheme of the instantaneous voltage sag corrector based on this detection algorithm. The validity of the proposed algorithm is verified through the EMTDC simulation and experiments.

The Detection of Voltage Sag using Wavelet Transform (웨이브렛 변환을 이용한 Voltage Sag 검출)

  • Kim, Cheol-Hwan;Go, Yeong-Hun
    • The Transactions of the Korean Institute of Electrical Engineers A
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    • v.49 no.9
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    • pp.425-432
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    • 2000
  • Wavelet transform is a new method fro electric power quality analysis. Several types of mother wavelets are compared using voltage sag data. Investigations on the use of some mother wavelets, namely Daubechies, Symlets, Coiflets, Biorthogonal, are carried out. On the basis of extensive investigations, optimal mother wavelets for the detection of voltage sag are chosen. The recommended mother wavelet is 'Daubechies 4(db4)' wavelet. 'db4', the most commonly applied mother wavelet in the power quality analysis, can be used most properly in disturbance phenomena which occurs rapidly for a short time. This paper presents a discrete wavelet transform approach for determining the beginning time and end time of voltage sags. The technique is based on utilising the maximum value of d1(at scale 1) coefficients in multiresolution analysis(MRA) based on the discrete wavelet transform. The procedure is fully described, and the results are compared with other methods for determining voltage sag duration, such as the RMS voltage and STFT(Short-Time Fourier Transform) methods. As a result, the voltage sag detection using wavelet transform appears to be a reliable method for detecting and measuring voltage sags in power quality disturbance analysis.

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NEW ADAPTIVE METHOD FOR VOLTAGE SAG AND SWELL DETECTION

  • Mohamed, Mansour A.
    • Journal of the Korea Convergence Society
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    • v.4 no.1
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    • pp.33-41
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    • 2013
  • This paper presents an adaptive recursive least squares algorithm (ARLS) for detecting voltage sag and voltage swell events in power systems. Different methods have been developed to detect voltage sag and voltage swell. Some of them use window techniques, which are too slow when voltage sag or swell mitigation is required. Others depend on the extraction of a single non-stationary sinusoidal signal out of a given multi-components input signal, and therefore they don't consider the harmonic components in calculating the voltage root mean square value (rms). The method, proposed in this paper, is capable of estimating the voltage rms taking into account all harmonic components. The method is tested by applying it to different, simulated signals using ATP program, and compared with voltage sag detection algorithms.

Development of Three Phase 10kW Voltage Sag Compensator (SEMI F47을 만족하는 10kW급 3상 전압 새그 보상기 개발)

  • Chae, Seung-Woo;Cho, Hyun-Sik;Lee, Il-Yong;Kong, Se-Il;Han, Byung-Moon;Cha, Han-Ju
    • The Transactions of the Korean Institute of Power Electronics
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    • v.17 no.3
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    • pp.198-204
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    • 2012
  • 3-Phase voltage sag compensator protects a critical load from grid sags. The paper presents an algorithm and design of 3-phase voltage compensator. Compensator algorithm consists of a 3-phase voltage sag detection, thyrister commutation method and inverter output voltage control. The compensator satisfies SEMI F47 standard and 10kW 3-phase voltage sag compensator prototype is assembled. Validity of the proposed compensator is verified by simulation and experiment.

The Space Vector Detection based Three-Phase Hybrid Series Active Power Filter for Compensating Dynamic Voltage Sag and Harmonic Current (순시전압 sag 및 고조파 전류 보상을 위한 공간벡터 검출법 기반의 3상 하이브리드 직렬형 능동전력필터)

  • 양승환;정영국;임영철
    • The Transactions of the Korean Institute of Power Electronics
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    • v.9 no.4
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    • pp.303-310
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    • 2004
  • In this paper, for compensating dynamic voltage sag and harmonic current, 3-phase hybrid series active power filter based on the space vector detection is proposed. The Space vector algorithm for detecting the voltage sag and the harmonic current in compared with conventional theory is a simple method for calculating the compensating reference without any coordinated transformation. The effectiveness of the proposed system is verified by the PSIM simulation in the steady state and the transient state, which the proposed system is able to simultaneously compensate harmonics and source voltage unbalance / sag.

Three-Phase Line-Interactive Dynamic Voltage Restorer with a New Sag Detection Algorithm

  • Jeong, Jong-Kyou;Lee, Ji-Heon;Han, Byung-Moon
    • Journal of Power Electronics
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    • v.10 no.2
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    • pp.203-209
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    • 2010
  • This paper describes the development of a three-phase line-interactive DVR with a new sag detection algorithm. The developed detection algorithm has a hybrid structure composed of an instantaneous detector and RMS-variation detectors. The source voltage passes through the sliding-window DFT and RMS calculator, and the instantaneous sag detector. If an instantaneous sag is detected, the RMS variation detector-1 is selected to calculate the RMS variation. The RMS variation detector-2 is selected when the instantaneous sag occurs under the operation of the RMS variation detector-1. The feasibility of the proposed algorithm is verified through computer simulations and experimental work with a prototype of a line-interactive DVR with a 3kVA rating. The line-interactive DVR with the proposed algorithm can compensate for an input voltage sag or an interruption within a 2ms delay. The developed DVR can effectively compensate for a voltage sag or interruption in sensitive loads, such as computers, communications equipment, and automation equipment.

Instantaneous Voltage Sag Corrector in Distribution Line Using Series Compensator (배전계통에서의 직렬보상을 이용한 순시전압강하 보상기)

  • Lee, Sang-Hoon;Choi, Jae-Ho
    • The Transactions of the Korean Institute of Electrical Engineers B
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    • v.50 no.1
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    • pp.15-22
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    • 2001
  • In this paper, a VSC(Voltage Sag Corrector) is discussed for the purpose of power quality enhancement. A fast detecting technique of voltage sag is accomplished through the detection of instantaneous value on synchronous reference frame. A robust characteristic against the noise is available by inserting the first order low pass filter in the detection circuit. The formula and the filter design process is described properly with the mathematical equations. Because the VSC system supply the active power to load, it is required to design the proper size of the energy storage system, In this paper, the capacitor bank is used as an energy storage system, and the size of the capacitor is designed from the point of view of input/output energy as the output power rating and the amplitude and duration time of the voltage sag. The simulation is accomplished by PSCAD/EMTDC.

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