• 제목/요약/키워드: Voltage sag

검색결과 366건 처리시간 0.021초

Design of a Series Voltage Sag Compensation System in Transmission Line

  • Park, Hyen-Young;Kim, Yang-Mo;Lee, Gyo-Sung;Oh, Se-Ho;Park, Jung-Gyun
    • KIEE International Transaction on Electrical Machinery and Energy Conversion Systems
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    • 제2B권4호
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    • pp.191-200
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    • 2002
  • When power consumption increases, power supply must be efficient and reliable for good power quality. The studies on compensation system of power quality are processing actively. Voltage sag among of factors for power quality is generally PI dual control that voltage sag compensation is used. But this control is no more available since of 120[KHz] ripple rejection. So we proposed the control algorithm using PID control in 3-phase unbalanced power system and the series voltage compensator, when voltage sag occurs.

친환경 Ultra-capacitor에 의한 순시전압강하의 직렬전압보상 시스템 (Series Voltage Compensation Systems for Voltage Sag by Using an Environmentally Friendly Ultra-capacitor)

  • 손진근;전희종
    • 전기학회논문지
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    • 제58권4호
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    • pp.763-769
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    • 2009
  • A series voltage compensation(SVC) system is a power-electronics controller that can protect sensitive loads from disturbance in the supply system. Especially, voltage sags are considered the dominant disturbances affecting the power quality. This paper dealt with a system of off-line type voltage sag compensation by using a bi-directional DC/DC converter of environmentally friendly ultra-capacitor. This capacitor is attached to the DC link of SVC through the high-efficiency DC/DC converter in order to compensate the DC link voltage drop during short-term power interruption as voltage sags. Therefore, in this paper, a DC/DC converter to control high-efficiency energy of ultra-capacitor and voltage sag detection algorithm of off-line type SVC systems are newly introduced. According to the results of experimental of prototype system, it is verified that the proposed system has effectiveness of voltage sag compensation using an ultra-capacitor.

전압 모니터링에 기반한 순간전압강하 확률적 추계 방법 (Stochastic Estimation of Voltage Sags Based on Voltage Monitoring)

  • 손정대;박창현
    • 전기학회논문지
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    • 제67권10호
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    • pp.1271-1277
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    • 2018
  • This paper deals with a voltage sag assessment based on a voltage monitoring program. The voltage sag performance at a specific site can be evaluated by analyzing voltage monitoring data recorded for a long time period. Although an assessment based on voltage monitoring is an effective way to understand voltage sag performance at a measurement site, the statistical confidence of voltage sag frequency estimation heavily depends on the length of monitoring period and the number of recorded events. Short monitoring period and insufficient recorded data can not provide a reliable assessment result. This paper proposes a compensation assessment method by combining a computer simulation approach for in case that monitoring period and data are not enough for a valid assessment.

A novel approach for optimal DG allocation in distribution network for minimizing voltage sag

  • Hashemian, Pejman;Nematollahi, Amin Foroughi;Vahidi, Behrooz
    • Advances in Energy Research
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    • 제6권1호
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    • pp.55-73
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    • 2019
  • The cost incurred by voltage sag effect in power networks has always been of important concern for discussions. Due to the environmental constraints, fossil fuel shortage crisis and low efficiency of conventional power plants, decentralized generation and renewable based DG have become trends in recent decades; because DGs can reduce the voltage sag effect in distribution networks noticeably; therefore, optimum allocation of DGs in order to maximize their effectiveness is highly important in order to maximize their effectiveness. In this paper, a new method is proposed for calculating the cost incurred by voltage sag effect in power networks. Thus, a new objective function is provided that comprehends technical standards as minimization of the cost incurred by voltage sag effect, active power losses and economic criterion as the installation and maintenance costs of DGs. Considering operational constraints of the system, the optimum allocation of DGs is a constrained optimization problem in which Lightning Attachment procedure optimization (LAPO) is used to resolve it and is the optimum number, size and location of DGs are determined in IEEE 33 bus test system and IEEE 34 bus test system. The results show that optimum allocation of DGs not only reduces the cost incurred by voltage sag effect, but also improves the other characteristics of the system.

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

  • 양승환;정영국;임영철
    • 전력전자학회논문지
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    • 제9권4호
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    • pp.303-310
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    • 2004
  • 본 연구에서는 순시전압 sag 및 고조파 전류 보상을 위한 공간벡터 검출법을 기반으로 한 3상 하이브리드 직렬형 능동전력필터 시스템을 제안하고 있다. 순시전안 sag 및 고조파 전류를 검출하기 위한 공간벡터 검출법은 종전의 이론에 비해 곱셈 연산 과정을 감소할 수 있고 좌표 변환이 필요치 않기 때문에 간략화한 보상 알고리즘 구현이 가능하다. 본 연구의 타당성은 전력전자전용 시뮬레이터 PSIM에 의해 정상상태와 과도상태에서 입증하였다. 그 결과 3상 교류 전원 모두에 순간적인 전압 sag가 발생되거나, 임의의 상에 왜형 및 sag가 있는 경우, 전압 보상 및 고조파 전류 보상이 모두 가능함을 입증하였다.

배전선로 고장에 의한 Voltage Sag의 특성 해석 (Characteristic Analysis of Voltage Sags Due to Faulted Distribution Lines)

  • 김성덕
    • 조명전기설비학회논문지
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    • 제16권1호
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    • pp.76-84
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    • 2002
  • 송전선과 배전선의 고장에 의한 voltage sag는 산업 수용가와 전력회사에 당면한 가장 중요한 전력품질(power quality) 문제들 중 하나가 되었다. voltage sag는 일반적으로 진폭과 지속시간 특성으로 기술되지만 voltage sag 현상을 규명하여 그 대책을 찾는데는 위상변위 특성을 반드시 고려해야 한다. 이 논문에서는 3상지락, 단선지락, 및 선간단락 사고가 발생하였을 경우에, 고장임피던스의 변화에 의한 voltage sag를 symmetrical components 해석을 이용하여 특성해석을 하였다. 이 때, voltage sag와 이들이 진폭과 위상에 미치는 효과를 고찰하였다. 3상지락과 같은 평형 고장은 모든 상에서 전압과 전류가 동일한 값으로 변화되고 또한 영상성분들은 영이 되었다. 그렇지만, 단선지락과 선간단락 고장과 같은 불평형 고장으로 인한 voltage sag는 진폭과 위상이 각 상마다 다르게 변화되었다. 해석결과를 확인하기 위하여 전력회로 모델들을 토대로 시뮬레이션을 수행하고 그 결과들도 검토되었다.

TCR을 이용한 Voltage Sag와 Swell 발생장치에 대한 연구 (Voltage Sag and Swell Generator with Thyristor Controlled Reactor)

  • 박태범;권기현;정용호;이진;임계영
    • 대한전기학회:학술대회논문집
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    • 대한전기학회 2002년도 하계학술대회 논문집 A
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    • pp.25-27
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    • 2002
  • This paper describes a new economical voltage sag and swell generator suitable to the evaluations of high power custom power devices such as DVR (Dynamic Voltage Restorer) and DSTATCOM (Distribution Static Compensator). This system was designed to generate the several power quality disturbances in MVA power ratings - voltage sag and swell, under voltage, over voltage and harmonic distortions. The basic idea for voltage sag and swell is to use the voltage drop across a reactor, while the voltage swell is to use the step-up transformer and the TCR(Thyristor Controlled Reactor). In this paper, two identical 3 phase TCRs and a step-up transformer with tap changer are used. Additional harmonic filters are added to reduce the voltage distortion when TCRs are operated. Simulation results are given for several cases of voltage sag and swell generations.

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순간전압강하 평가에 기반한 최적 보상기기 선정 방법 (Method to Select Optimal Device for Mitigating Voltage Sag Based on Voltage Sag Assessment)

  • 이계병;한종훈;장길수;박창현
    • 전기학회논문지
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    • 제64권1호
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    • pp.29-34
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    • 2015
  • This paper presents a method to select optimal device for mitigating voltage sags. The method is based on economic evaluation and voltage sag assessment involving sag duration as well as magnitude. The economic evaluation is performed by using the operation cost and economic benefit of the mitigation devices. The optimal device can be determined from the values of NPV (net present value) which is widely accepted in cost-benefit analysis. The proposed method can help sensitive customers to select optimal mitigation device. In this paper, the case study considering two sensitive customers was performed by using the proposed method.

Voltage Sag에 의한 고압 방전등의 운전한계 특성 연구 (A study on the characteristics of operating limits of High-Pressure discharge lamps during Voltage Sag)

  • 정성원;황건호;이현철;이근준;김재현
    • 한국조명전기설비학회:학술대회논문집
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    • 한국조명전기설비학회 2008년도 춘계학술대회 논문집
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    • pp.37-40
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    • 2008
  • This paper presents the results of a simulation to analyze the effects of voltage sag on high-pressure discharge lamp(400[W]). In this paper, voltage sag is considered a reduction between 0 and 0.9[p.u] in nominal voltage magnitude, with duration between 0.01 and 90cycle. The simulation results depict the characteristics of the lamp about operating limits during voltage sag by the magnitude and duration of sag in CBEMA curve.

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Fast Detection Algorithm for Voltage Sags and Swells Based on Delta Square Operation for a Single-Phase Inverter System

  • Lee, Woo-Cheol;Sung, Kook-Nam;Lee, Taeck-Kie
    • Journal of Electrical Engineering and Technology
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    • 제11권1호
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    • pp.157-166
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    • 2016
  • In this paper, a new sag and peak voltage detector is proposed for a single-phase inverter using delta square operation. The conventional sag detector is from a single-phase digital phase-locked loop (DPLL) that is based on d-q transformations using an all-pass filter (APF). The d-q transformation is typically used in the three-phase coordinate system. The APF generates a virtual q-axis voltage component with a 90° phase delay, but this virtual phase cannot reflect a sudden change in the grid voltage at the instant the voltage sag occurs. As a result, the peak value is drastically distorted, and it settles down slowly. A modified APF generates the virtual q-axis voltage component from the difference between the current and the previous values of the d-axis voltage component in the stationary reference frame. However, the modified APF cannot detect the voltage sag and peak value when the sag occurs around the zero crossing points such as 0° and 180°, because the difference voltage is not sufficient to detect the voltage sag. The proposed algorithm detects the sag voltage through all regions including the zero crossing voltage. Moreover, the exact voltage drop can be acquired by calculating the q-axis component that is proportional to the d-axis component. To verify the feasibility of the proposed system, the conventional and proposed methods are compared using simulations and experimental results.