고조파원의 등가 전류원 모델 추정에 기반한 고조파 전류 기여도 평가

박종일,박창현 대한전기학회 2023 전기학회논문지 Vol.72 No.4

This paper presents a method for evaluating harmonic contributions to current distortion injected into a utility system from multiple harmonic sources at the point of common coupling (PCC). For effective harmonic management, it is necessary to identify harmonic sources and to evaluate their contribution to harmonic current distortion. Basically, to evaluate the harmonic contribution, the equivalent current source model of each harmonic source is required. The proposed method estimates the harmonic current source and impedance parameters of the equivalent model using the data measured at PCC and the recursive least squares (RLS) algorithm with variable forgetting factor. The harmonic current contribution can be also evaluated using the principle of current superposition with the estimated harmonic equivalent current model. The performance of equivalent model parameter estimation and harmonic contribution evaluation of the proposed method was analyzed through a case study using the PSCAD/EMTDC test system.

배전 시스템의 고조파 분석 및 모델링에 관한 연구

왕용필,정종원,정동일,Wang, Yong-Peel,Jeong, Jong-Won,Jeong, Dong-Il 한국조명전기설비학회 2007 조명·전기설비학회논문지 Vol.21 No.3

최근 전력 전자 응용 기기의 사용증가로 비선형 특성 부하에 의한 고조파가 상당히 발생하고 있으며, 이에 의한 영향으로 배전시스템의 변압기 열화, 소자의 고장, 통신 간섭 등의 여러 가지 문제를 발생시키고 있다. 따라서 배전 시스템에서의 고조파 수준과 전달특성을 정확하게 분석하기 위하여 배전시스템의 효과적인 실측정과 모델링에 관한 연구가 필요한 실정이다. 본 논문에서는 고조파 관리기준 IEC61000-3-6 토대로 배전 시스템의 고조파 특성을 해석하기 위하여 공통 결합점(Point of Common Coupling : PCC)을 선택하였다. 실 배전 시스템의 PCC 지점에서 고조파 전압, 전류를 측정하여, 고조파 분포, 비선형 부하 성분 및 고조파 전압, 전류 왜형률 (Voltage/Current Total Harmonic Distortion: VTHD/ITHD)을 분석하였다. 또한 정상상태에서 고조파 임피던스, 전압, 전류을 해석을 통하여 실 배전시스템을 효과적이고 정확하게 모델링 되었을 확인하였다. 또한 고조파 전류원 발생시에 고조파 전압, 전류를 비교 분석하여 고조파 전달특성을 조사하였다. The increasing use of power electronic equipment in distribution system has been the reason for the greater concern about a harmonic in recent time. Therefore, it is necessary for measurement and modelling to analyze a harmonic level and a transfer characteristic in distribution system. In this paper, the Point of Common Coupling (PCC) is selected to analyze harmonic characteristic of distribution system by IEC 61000-3-6. Harmonic voltage and orient were measured at the PCC of real distribution system Harmonic distribution, nonlinear load component and Total Harmonic Distortion(THD) were verified. The effective and accurate modelling of real distribution system were proved through a analysis of harmonic impedance, voltage and current under steady-state. Harmonic transfer characteristic were investigated through a analysis of harmonic voltage and current under harmonic current source.

Impedance-based harmonics compensation with accurate harmonic power sharing in distorted microgrids

Pham, Minh-Duc,Lee, Hong-Hee The Korean Institute of Power Electronics 2021 JOURNAL OF POWER ELECTRONICS Vol.21 No.2

This paper presents an enhanced compensation strategy for distributed generation (DG) systems to simultaneously achieve accurate power sharing and harmonics compensation at the point of common coupling (PCC). In the proposed control strategy, the output impedance is modified at the fundamental and harmonic frequencies to compensate for the line impedance mismatches among DG units, which results in accurate power sharing. In addition, load harmonic currents are effectively adjusted by the DG units to effectively compensate the PCC voltage harmonics. Additionally, the DG equivalent impedance is regulated adaptively to ensure accurate harmonic power sharing even in the presence of sudden load changes. Furthermore, a distributed communication network is adopted instead of a central controller to increase the reliability and stability of the microgrid system. The proposed control strategy is applied to a prototype microgrid system, and its effectiveness and reliability are experimentally validated.

An MRAS based Current Harmonics Reduction for Three Phase PWM Rectifier under Input Voltage Distortion

Hee Keun Shin,Byung Chul Yoon,Hag Wone Kim,Kwan Yuhl Cho,Byung Kuk Lim,Soon Sang Hwang 전력전자학회 2011 ICPE(ISPE)논문집 Vol.2011 No.5

The input voltage distortion in the three phase PWM rectifier is a main factor in the input current distortion and the voltage ripples across the DC link capacitor. This paper presents the MRAS(Model Reference Adaptive System) based input current harmonics reduction for the PWM rectifier under the input voltage distortion. The dq compensating voltages produced from the dq current difference between real system and the estimator model make up for the effect of the source voltage harmonics on the phase currents. The performance of the proposed algorithm is verified through the simulation and the experiment.

A Simple Switched Capacitor Compensator to Minimize Zero-Crossing Distortion in Single-Phase PFC Converters

Yan Zhang,Jinjun Liu,Chaoyi Zhang 전력전자학회 2011 ICPE(ISPE)논문집 Vol.2011 No.5

This paper explorers techniques for minimizing zero-crossing distortion in single-phase PFC converters from the angle of topologies. Zero-crossing distortions of typical single-phase PFC topologies are compared in theory to reveal that cusp distortion is predominant responsible for zero-crossing distortion. PWM rectifier with the capability of bi-directional current can minimum and eliminate zerocrossing distortion even though there is phase displacement in current loop at the cost of increasing switching loss and larger boost inductor. Then, a simple switched capacitor compensation scheme with low voltage rating switching devices and low switching frequency is presented to minimum zero-crossing distortion. Furthermore, the proposed switched capacitor circuit can be added to existing single-phase PFC converters without modification of original topologies and controllers, hence it is economically feasible. Numerical simulations are given to validate the theoretical analysis and effectiveness of the proposed scheme. With switched capacitor compensator, single-phase PFC converters demonstrate good input performance.

Direct Harmonic Voltage Control Strategy of Shunt Active Power Filters Suitable for Microgrid Applications

Munir, Hafiz Mudassir,Zou, Jianxiao,Xie, Chuan,Li, Kay,Younas, Talha,Guerrero, Josep M. The Korean Institute of Power Electronics 2019 JOURNAL OF POWER ELECTRONICS Vol.19 No.1

The application of shunt active power filters (S-APFs) is considered to be the most popular approach for harmonic compensation due to its high simplicity, ease of installation and efficient control. Its functionality mainly depends upon the rapidness and precision of its internally built control algorithms. A S-APF is generally operated in the current controlled mode (CCM) with the detection of harmonic load current. Its operation may not be appropriate for the distributed power generation system (DPGS) due to the wide dispersion of nonlinear loads. Despite the fact that the voltage detection based resistive-APF (R-APF) appears to be more appropriate for use in the DPGS, the R-APF experiences poor performance in terms of mitigating harmonics and parameter tuning. Therefore, this paper introduces a direct harmonic voltage detection based control approach for the S-APF that does not need a remote harmonic load current since it only requires a local point of common coupling (PCC) voltage for the detection of harmonics. The complete design procedure of the proposed control approach is presented. In addition, experimental results are given in detail to validate the performance and superiority of the proposed method over the conventional R-APF control. Thus, the outcomes of this study approve the predominance of the discussed strategy.

3상 유도전동기 운전에 대한 고조파 위상각 영향의 분석

고성필,좌종근 제주대학교 공과대학 첨단기술연구소 2005 尖端技術硏究所論文集 Vol.16 No.2

This paper describes an analysis of the effect of low harmonic orders and phase angles on the operation performance of a three-phase induction motor. In the analysis, the voltage harmonic orders from 2 to 7, with the three different voltage distortion factors were chosen except the triple harmonics, and each harmonic order was designed into four kinds of waveforms whose phase angles are divided one cycle into four parts. The analyzed data includes current distortion factor, voltage form factor, current form factor, input voltage, input current, and efficiency. From the analyzed result, it is found that the operation performance of a three-phase induction motor does not vary by phase angle of each individual harmonic order. But both voltage and current form factors related to the waveforms are affected by the harmonic phase angle in odd harmonics.

Amplification of Current Harmonics Due to Self-Excitation Capacitors for Wind Induction Generators

吳鏞(Yong Oh),崔龍成(Yong-Sung Choi),黃宗善(Jong-Sun Hwang),李炅燮(Kyung-Sup Lee) 대한전기학회 2008 전기학회논문지 P Vol.57 No.2

The value of this paper is to use reduced size apparatuses to perform field measurement in order to identify and validate that the harmonic-current effects are due to the presence of self-excitation capacitance connected at stator's terminals of the studied SEIG. This paper has presented the measured electrical quantities of a three-phase Δ-connected wind induction generator (WIG) under sudden connection and disconnection of resistive loads. An intelligent power-system recorder/monitor has been employed to measure three-phase voltages and currents of the studied system at the terminals of the studied WIG and the load. The measured electrical quantities have been analyzed. Total harmonic distortion (THD) of current using cumulative probability density function has been employed to determine the penetration of harmonic distortion at load side. The results show that the harmonic currents generated by the studied WIG can be severely amplified by the connected self-excited capacitance at the stator's terminals.

Carrier based SVPWM Method for Multi-Level System Considering Harmonic Distortion Factor

Lee, Yo-Han,Kim, Dong-Hyun,Hyun, Dong-Seok The Korean Institute of Power Electronics 2001 JOURNAL OF POWER ELECTRONICS Vol.1 No.1

In most inverter/converter applications SVPWM method is a preferred approach since it shows good characteristics in linear modulation range and waveform quality. In this paper, we propose a new carrier based SVPWM method for multi-level system, First, we survey the conventional carrier based SVPWM method, and investigate the problem of the conventional one for the multi-level system with the focus on the switching frequency harmonic flux trajectories. Finally, we propose a new carrier based SVPWM method that can reduce harmonic distortion. Simulation and experimental results are given for verification of the proposed SVPWM method.

A Comparative Study on Power System Harmonics for Offshore Plants

Deok-Ki Kim,Won-Ju Lee,Jong-Su Kim 해양환경안전학회 2016 海洋環境安全學會誌 Vol.22 No.7

해양구조물에 전기 안전사고가 급증하면서 전력시스템 고조파 분야가 최근 많은 관심 받고 있다. 이것은 주로 비선형 (또는 고조파 생성) 부하가 일반적인 산업플랜트 전력시스템에서 계속 증가되고 있기 때문이다. 해양플랜트에서는 전력시스템의 안전설계로 인하여 고조파 문제의 발생률은 낮지만, 고조파 문제에 대한 인식은 전력시스템 설계의 신뢰성을 향상시키는데 여전히 도움이 될 수 있다. 전력시스템에 고조파 문제가 드물게 발생되는 경우, 이는 생성된 고조파의 크기 혹은 전력시스템의 공진 때문이다. 이 고조파 비교분석에 관한 연구는 전력부하를 고려한 부유식 액화천연가스 생산·저장·하역 (FLNG) 설비의 하역 운전 시나리오에 대한 전기적인 구성으로 비교분석하였다. 전기적인 네트워크 구성은 전기적인 네트워크 부하 흐름에서 볼 수 있다. 본 연구는 해양플랜트 전력시스템의 안전을 보장하기 위해 전기 모터 시스템의 고조파 효율에 초점을 맞추어 전력시스템 성능을 시뮬레이션을 통해 검증하였다. 또한, 본 연구의 설계분야에서도 운전 및 유지·보수의 향상시키기 위해 FLNG 설비의 전력시스템을 분석하였다. The field of power system harmonics has been receiving a great deal of attention recently. This is primarily due to the fact that non-linear (or harmonic-producing) loads comprise an ever-increasing portion of what is handled at a typical industrial plant. The incidence rate of harmonic-related problems is low, but awareness of harmonic issues can still help increase offshore power plant system reliability. On the rare occasion that harmonics become a problem, this is either due to the magnitude of harmonics produced or power system resonance. This harmonic study used an electrical configuration for the offloading scenario of a Floating LNG (FLNG) unit, considering power load. This electrical network configuration is visible in the electrical network load flow study part of the project. This study has been carried out to evaluate the performance of an electric power system, focusing on the harmonic efficiency of an electrically driven motor system to ensure offshore plant safety. In addition, the design part of this study analyzed the electric power system of an FLNG unit to improve the safety of operation and maintenance.