• 제목/요약/키워드: single-phase grid-connected

검색결과 154건 처리시간 0.027초

PV Array 출력리플 저감을 위한 계통연계형 태양광 인버터에 관한 연구 (Study on the Grid-connected Photovoltaic Power System for Reducing Ripples of the PV Array Output)

  • 김희중;정용호;이기수;전영수
    • 대한전기학회:학술대회논문집
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    • 대한전기학회 2007년도 제38회 하계학술대회
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    • pp.1211-1212
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    • 2007
  • In the PV power system, output of the PV array must contain inherent ripples due to the single-phase inverter. So, the function of maximum power point tracking to increase the output efficiency of PV system is degraded. Therefore, to overcome this problem, this paper presents a control strategy for the reducing ripples of the PV array output in grid-connected photovoltaic power system. The proposed control system consists of two loops; the maximum power point tracking loop using the perturbation and observation method is used to calculate the reference solar array terminal voltage(Vref) for reducing ripples of the PV array output and the PI control loop is used to regulate the solar array output voltage according to the Vref. The performance of proposing control strategy is analyzed by means of the PSCAD/EMTDC simulation and experiment. As a result, we may obtain the high performance of the proposed control strategy.

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계통연계헝 태양광인버터의 PV Array 출력리플 저감을 위한 연구 (Study for Reducing Ripples of the PV Array Output in Grid-Connected Photovoltaic Power System)

  • 김희중;정용호;이기수;전영수
    • 한국신재생에너지학회:학술대회논문집
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    • 한국신재생에너지학회 2006년도 춘계학술대회
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    • pp.202-205
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    • 2006
  • In the PV power system, output of the PV array must contain inherent ripples due to the single-phase inverter. So the function of maximum power point tracking to increase the output efficiency of PV system is degraded. Therefore, to overcome this problem, this paper presents a control strategy for the reducing ripples of the PV array output in grid-connected photovoltaic power system. The proposed control system consists of two loops the maximum power point tracking loop using the perturbation and observation method is used to calculate the reference solar array terminal voltage(Vref) for reducing ripples of the PV array output and the PI control loop is used to regulate the solar array output voltage according to the Vref. The performance of proposing control strategy is analyzed by means of the PSCAD/EMTDC simulation. As a result, we may obtain the high performance of the proposed control strategy.

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LCL 필터가 결합된 단상 계통연계형 인버터의 안정화를 위한 적응형 디지털 노치 필터 (An Adaptive Digital Notch Filter for Stabilization of Single-Phase Grid-Connected Inverters With LCL Filter)

  • 허진용;김학수;노의철
    • 전력전자학회논문지
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    • 제26권5호
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    • pp.307-314
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    • 2021
  • Even though the LCL filters have superior harmonic attenuation ability to L filters, stability has always been an issue. The system could be unstable because of the resonance phenomenon, especially when digital controller is used. Adding a notch filter to the compensator is one approach to solve the problem. Resonance phenomenon can be inhibited by aligning notch frequency to system resonance frequency. However, resonance frequency variation can be obtained because the actual system has a nonstationary characteristic. Therefore, the system could be unstable, where the system parameters are changed when the conventional notch filter is used. An adaptive digital notch filter that stabilizes the system even system parameters are changed. Simulation and experiment results are provided to verify the validity of the proposed adaptive filter.

A Resonant Characteristics Analysis and Suppression Strategy for Multiple Parallel Grid-connected Inverters with LCL Filter

  • Sun, Jian-jun;Hu, Wei;Zhou, Hui;Jiang, Yi-ming;Zha, Xiao-ming
    • Journal of Power Electronics
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    • 제16권4호
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    • pp.1483-1493
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    • 2016
  • Multiple parallel inverters have multiple resonant frequencies that are influenced by many factors. This often results in stability and power quality problems. This paper develops a multiple input multiple output model of grid-connected inverter systems using a closed-loop transfer function. The influence factors of the resonant characteristics are analyzed with the developed model. The analysis results show that the resonant frequency is closely related to the number, type and composition ratio of the parallel inverters. To suppress resonance, a scheme based on virtual impedance is presented, where the virtual impedance is emulated in the vicinity of the resonance frequency. The proposed scheme needs one inverter with virtual impedance control, which reduces the design complexity of the other inverter controllers. Simulation and experimental tests are carried out on two single phase converter-based setups. The results validate the correctness of the model, the analytical results and the resonant suppressing scheme.

Optimized Hybrid Modulation Strategy for AC Bypass Transformerless Single-Phase Photovoltaic Inverters

  • Deng, Shuhao;Sun, Yao;Yang, Jian;Zhu, Qi;Su, Mei
    • Journal of Power Electronics
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    • 제16권6호
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    • pp.2129-2138
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    • 2016
  • The full-bridge inverter, widely used for single-phase photovoltaic grid-connected applications, presents a leakage current issue. Therefore, an AC bypass branch is introduced to overcome this challenge. Nevertheless, existing modulation strategies entail drawbacks that should be addressed. One is the zero-crossing distortion (ZCD) of the AC current caused by neglecting the AC filter inductor voltage. Another is that the system cannot deliver reactive power because the AC bypass branch switches at the power frequency. To address these problems, this work proposes an optimized hybrid modulation strategy. To reduce ZCD, the phase angle of the inverter output voltage reference is shifted, thereby compensating for the neglected leading angle. To generate the reactive power, the interval of the negative power output is calculated using the power factor. In addition, the freewheeling switch is kept on when power is flowing into the grid and commutates at a high frequency when power is fed back to the DC side. In this manner, the dead-time insertion in the high-frequency switching area is minimized. Finally, the performances of the proposed modulation strategy and traditional strategies are compared on a universal prototype inverter. Experimental results validate the theoretical analysis.

변압기 없는 계통연계형 PV PCS고찰 (Transformer-less Type Grid-Connected PV Power Conditioning System)

  • 정영석;유권종;정명웅;최재호;최주엽
    • 전력전자학회:학술대회논문집
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    • 전력전자학회 2002년도 전력전자학술대회 논문집
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    • pp.551-554
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    • 2002
  • This paper describes a new interactive inverter between a photovoltaic(PV) array and single-phase utility that avoid the bulky input (60Hz) transformer on the AC side. The interface employs a pwm boost converter on the DC side followed by a pwm current-forced single-phase rectifier for injecting the power from the PV array into the mains. The current waveform at the AC side remains sinusoidal and exactly in phase at all time. The circuit also has the advantage of requiring fewer switching device than high-frequency link system. This paper describes modeling of PV array and new system topology. Simulation results on the performance of the connection are also presented.

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개선된 DFT을 이용한 무효전력변동 단독운전 검출기법의 성능 개선 (Performance Improvement of an Anti-Islanding Algorithm using the Variation of Reactive Power with an Improved DFT Method)

  • 강덕홍;최대근;이교범
    • 전력전자학회논문지
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    • 제15권3호
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    • pp.179-187
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    • 2010
  • 본 논문에서는 무효전력변동기법을 사용하여 단독운전을 검출을 하기 위해서 선행되어야 하는 주파수 검출 방법 중에서 개선된 이산푸리에변환(Discrete Fourier Transform; DFT), 즉 Goertzel 알고리즘을 이용한 단독운전 검출기법을 제안한다. 실제 태양광 발전 시스템의 설치를 위해서는 전기사고나 시스템에 악영향을 유발하는 단독운전 검출기법의 연구가 선행되어야 한다. 적용하는 주파수 검출방법은 Goertzel 알고리즘을 이용한 기법으로 기존의 영점검출기법과 가상의 2상 PLL(Phase Locked Loop)에 비하여 외란의 영향에 강인하며 빠른 검출이 가능하다. 시뮬레이션 및 실험을 통하여 기존의 주파수검출기법인 영점검출기법과 가상의 2상 PLL을 이용한 주파수 검출과 제안하는 알고리즘을 비교하고 그의 우수성을 검증하였다.

단상 계통연계형 인버터의 영 전압 사고 위상에 따른 PLL 동적 특성 분석 (Analysis of PLL Dynamic Characteristics according to Zero Voltage Conditions of Single-phase Grid-connected Inverter)

  • 이태일;이경수
    • 전력전자학회:학술대회논문집
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    • 전력전자학회 2019년도 전력전자학술대회
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    • pp.80-82
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    • 2019
  • 태양광발전과 풍력발전으로 대표되는 분산형 전원이 계통에 연계됨에 따라 계통 사고 발생 시에 계통연계형 인버터에 대한 각국의 계통 규정(Grid code)이 더욱 엄격해 지고 있다. 최근 국외 계통 규정에서는 저 전압 사고뿐만 아니라 영 전압 사고 시에 인버터가 일정 시간 계통 연계를 유지하며 무효전류 출력 기법을 통해 계통 복구를 지원할 것을 요구하고 있다. 계통 사고 시, 사고 전압 잔존량에 따라 무효전류를 정확하게 출력하기 위해 인버터의 PLL(Phase Locked Loop) 제어는 중요하다. 그러나 이러한 PLL 제어의 동적 특성은 계통 사고 순간의 전압 강하 및 사고 위상에 따라 영향을 받게 되고 영 전압 사고에서는 위상 추종이 불가능하기 때문에 복합적인 문제가 나타난다. 본 논문에서는 영 전압 사고에서 사고 위상에 따라 각각 다르게 나타나는 PLL 동적 특성을 시뮬레이션을 통해 분석하였다.

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능동 전력 디커플링을 위한 3권선 방식의 플라이백 인버터 설계 (Design of Three-port Flyback Inverter for Active Power Decoupling)

  • 김규동;김준구;이태원;정용채;원충연
    • 전력전자학회:학술대회논문집
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    • 전력전자학회 2012년도 전력전자학술대회 논문집
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    • pp.486-487
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    • 2012
  • In this paper, novel three-port active power decoupling (APD) method for applying 250[W] micro-inverter. This type using third port for active power decoupling stores the surplus energy and supplies sufficient energy to grid. Conventional decoupling circuit is applied in single phase grid connected micro-inverter especially single-stage configuration like flyback-type DC-AC inverter. In this passive power decoupling method, electrolytic capacitor with large capacitance is needed for decoupling from constant DC power and instantaneous AC power. However the decoupling capacitor is replaced with film capacitor by using APD, thus the overall system can achieve smaller size and long lifespan. Proposed three-port flyback inverter is verified by design and simulation.

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단상 UPS 시스템의 모드 절환 시퀀스 및 제어 (Mode Transfer Sequence and Control of Single-phase UPS System)

  • 이상석;이순령;최봉연;이정효;원충연
    • 조명전기설비학회논문지
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    • 제28권12호
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    • pp.108-115
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    • 2014
  • Recently, Uninterruptible power supply(UPS) is spotlighted from concern about black out, due to reserve power problem caused by increased power consumption. When fault occurs on the grid, UPS system supplies power to loads instead of the grid. Also, it is an advantage of possible operation as Energy storage system(ESS). Bi-directional power control of AC/DC Pulse width modulation(PWM) converter is essential for grid-connected UPS system. And, mode transfer control has to be performed considering phase and dynamic characteristic under grid condition. In this paper, control of mode transfer and bi-directional power control of AC/DC PWM converter is proposed for UPS system. Also, it is verified by simulation and experimental results.