• Title/Summary/Keyword: Micro-inverter

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A Novel Multi-Function PV Micro-Inverter with an Optimized Harmonic Compensation Strategy

  • Zhu, Guofeng;Mu, Longhua;Yan, Junhua
    • Journal of Power Electronics
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    • v.16 no.6
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    • pp.2284-2293
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    • 2016
  • With the rapid development of clean energy, photovoltaic (PV) generation has been utilized in the harmonic compensation of power systems. This paper presents a novel multi-function PV micro-inverter with three stages (pseudo-two-stage). It can inject active power and compensate harmonic currents in the power grid at the same time. In order to keep the micro-inverter working under the maximum allowable output power, an optimized capacity limitation strategy is presented. Moreover, the harmonic compensation can be adjusted according to the customized requirements of power quality. Additionally, a phase shedding strategy in the DC/DC stage is introduced to improve the efficiency of parallel Boost converters in a wide range. Compared with existing capacity limitation methods, the proposed strategy shows better performance and energy efficiency. Simulations and experiments verify the feasibility of the micro-inverter and the effectiveness of the strategy.

Power Conditioning for a Small-Scale PV System with Charge-Balancing Integrated Micro-Inverter

  • Manoharan, Mohana Sundar;Ahmed, Ashraf;Seo, Jung-Won;Park, Joung-Hu
    • Journal of Power Electronics
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    • v.15 no.5
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    • pp.1318-1328
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    • 2015
  • The photovoltaic (PV) power conditioning system for small-scale applications has gained significant interest in the past few decades. However, the standalone mode of operation has been rarely approached. This paper presents a two-stage multi-level micro-inverter topology that considers the different operation modes. A multi-output flyback converter provides both the DC-Link voltage balancing for the multi-level inverter side and maximum power point tracking control in grid connection mode in the PV stage. A modified H-bridge multi-level inverter topology is included for the AC output stage. The multi-level inverter lowers the total harmonic distortion and overall ratings of the power semiconductor switches. The proposed micro-inverter topology can help to decrease the size and cost of the PV system. Transient analysis and controller design of this micro-inverter have been proposed for stand-alone and grid-connected modes. Finally, the system performance was verified using a 120 W hardware prototype.

Design and Implementation of Wireless Intelligent Controller for Micro-Inverter in Solar Power Systems (태양광 발전시스템에서 사용하는 마이크로인버터용 무선지능형제어기 설계 및 구현)

  • Han, Seongtaek
    • Journal of Korea Society of Digital Industry and Information Management
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    • v.15 no.4
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    • pp.9-17
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    • 2019
  • Sun power generation systems which use large capacity centralized inverters have loss of power generation due to cloud and building shadows, pollution, cell deterioration, etc. To minimize loss of power generation, decentralized solar power systems using multiple micro-inverters are being proposed as an alternative. A distributed solar power system consisting of a system-connected system uses power line communication to collect data from the micro-inverters. Power line communication has the advantage of using power lines without separate lines for data transmission, but in distributed solar power generation systems that use a large number of micro-inverters, the bit error rate is less reliable due to the phenomenon caused by limited transmission power, high load interference and noise, variable signal attenuation, and impedance characteristics. So we proposed wireless intelligent controller for micro-inverter that is used to build distributed solar power systems. and we design and implement that. Further, the proposed wireless intelligent controller for micro-inverter was used to establish a small-volume solar power plant to check its function and operation.

A Study on the Technical Standard of Micro-Inverter for Domestic Photovoltaic Power Generation (국내 태양광발전용 마이크로 인버터 기술기준에 관한 연구)

  • Yoon, Yongho
    • The Journal of the Institute of Internet, Broadcasting and Communication
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    • v.19 no.2
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    • pp.175-180
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    • 2019
  • In order to overcome the drawbacks of low rated power of the string inverter, the necessity of micro -inverters and future development directions will be examined by comparing the power conditioner system with existing PCS using micro inverter. Currently, string inverters have been used in household solar power generation systems, and research and penetration of micro-inverters(PV-MIC) have been expanding, which can overcome the shortcomings of string inverters starting from Europe. However, in the PV inverter industry, precise technical standards, test measurement equipment and related test methods for micro-inverters(PV-MIC) are obstacles to product development. Therefore, in this paper, considering the characteristics of micro-inverter (PV-MIC), it aims to make it competitive so that it does not lag behind advanced technology change through test measurement equipment and related technical standard.

Sliding Mode Controller Applied to Coupled Inductor Dual Boost Inverters

  • Fang, Yu;Cao, Songyin;Wheeler, Pat
    • Journal of Power Electronics
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    • v.19 no.6
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    • pp.1403-1412
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    • 2019
  • A coupled inductor-dual boost-inverter (CIDBI) with a differential structure has been presented for application to a micro-inverter photovoltaic module system due to its turn ratio of a high-voltage level. However, it is difficult to design a CIDBI converter with a conventional PI regulator to be stable and achieve good dynamic performance, given the fact that it is a high order system. In view of this situation, a sliding mode control (SMC) strategy is introduced in this paper, and two different sliding mode controllers (SMCs) are proposed and adopted in the left and right side of two Boost sub-circuits to implement the corresponding regulation of the voltage and current. The schemes of the SMCs have been elaborated in this paper including the establishment of a system variable structure model, selection of the sliding surface, determination of the control law, and presentation of the reaching conditions and sliding domain. Finally, the mathematic analysis and the proposed SMC are verified by experimental results.

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

  • Kim, Kyu-Dong;Kim, Jun-Gu;Lee, Tae-Won;Jung, Yong-Chae;Won, Chung-Yuen
    • Proceedings of the KIPE Conference
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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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Study on the Obsolescence Forecasting Judgment of PV Systems adapted Micro-inverters (마이크로인버터를 적용한 태양광 발전시스템 노후예측판단에 관한 연구)

  • Park, Chan Khon
    • Journal of Korea Multimedia Society
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    • v.18 no.7
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    • pp.864-872
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    • 2015
  • The purpose of this study is to design the algorithm, Predictive Service Component - PSC, for forecasting and judging obsolescence of solar system that is implemented based on the micro-inverter. PSC proposed in this study is suitable for monitoring of distributed power generation systems. It provides a diagnosis functionality to detect failures and anomaly events. It also can determine the aging of PV systems. The conclusion of this study shows the research and development of this kind of integrated system using PSC will be needed more and varied in the near future.

Low-Cost High-Efficiency Two-Stage Cascaded Converter of Step-Down Buck and Tapped-Inductor Boost for Photovoltaic Micro-Inverters (태양광 마이크로 인버터를 위한 탭인덕터 부스트 및 강압형 컨버터 캐스케이드 타입 저가형 고효율 전력변환기)

  • Jang, Jong-Ho;Shin, Jong-Hyun;Park, Joung-Hu
    • The Transactions of the Korean Institute of Power Electronics
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    • v.19 no.2
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    • pp.157-163
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    • 2014
  • This paper proposes a two-stage step-down buck and a tapped-inductor boost cascaded converter for high efficiency photovoltaic micro-inverter applications. The proposed inverter is a new structure to inject a rectified sinusoidal current into a low-frequency switching inverter for single-phase grid with unity power factor. To build a rectified-waveform of the output current. the converter employs both of a high efficiency step-up and a step-down converter in cascade. In step-down mode, tapped inductor(TI) boost converter stops and the buck converter operates alone. In boost mode, the TI converter operates with the halt of buck operation. The converter provides a rectified current to low frequency inverter, then the inverter converts the current into a unity power-factor sinusoidal waveform. By applying a TI, the converter can decrease the turn-on ratios of the main switch in TI boost converter even with an extreme step-up operation. The performance validation of the proposed design is confirmed by an experimental results of a 120W hardware prototype.

Active Frequency Drift Method for Islanding Detection Applied to Micro-inverter with Uncontrollable Reactive Power

  • Kwak, Raeho;Lee, June-Hee;Lee, Kyo-Beum
    • Journal of Power Electronics
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    • v.16 no.5
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    • pp.1918-1927
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    • 2016
  • This paper proposes active frequency drift (AFD) as an anti-islanding method applied to micro-inverters with uncontrollable reactive power. When using ordinary inverter topologies, such as full bridge inverters in photovoltaic systems, the islanding phenomenon can be detected with reactive power-based methods, such as reactive power variation. However, when the inverter topology cannot control the reactive power, conventional anti-islanding methods with reactive power cannot be utilized. In this work, the topology used in this paper cannot control the reactive power. Thus, an anti-islanding method that can be used in topologies that cannot control the reactive power is proposed. The conventional anti-islanding method of the topology that cannot control reactive power is introduced and analyzed. Unlike the conventional AFD method, the proposed method extends a zero current interval every predetermined cycle. The proposed method offers certain advantages over conventional AFD methods, such as total harmonic distortion. The proposed method is validated through simulation and experiment.

New Control Method for Power Decoupling of Electrolytic Capacitor-less Photovoltaic Micro-Inverter with Primary Side Regulation

  • Irfan, Mohammad Sameer;Shin, Jong-Hyun;Park, Joung-Hu
    • Journal of Electrical Engineering and Technology
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    • v.13 no.2
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    • pp.677-687
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    • 2018
  • This paper presents a novel power decoupling control scheme with the bidirectional buck-boost converter for primary-side regulation photovoltaic (PV) micro-inverter. With the proposed power decoupling control scheme, small-capacitance film capacitors are used to overcome the life-span and reliability limitations of the large-capacitance electrolytic capacitors. Then, an improved flyback PV inverter is employed in continuous conduction mode with primary-side regulation for the PV power conditioning. The proposed power-decoupling controller shares the reference for primary side current regulation of the flyback PV inverter. The decoupling controller shapes the input current of the bidirectional buck-boost converter. The shared reference eliminates the phase-delay between the input current to the bidirectional buck-boost converter and the double frequency current at the PV primary current. The elimination of the phase-delay in dynamic response enhances the ripple rejection capability of the power decoupling buck-boost converter even with small film capacitor. With proposed power decoupling control scheme, the additional advantage of the primary-side regulation of flyback PV inverter is that there is no need to have an extra current sensor for obtaining the ripplecurrent reference of the decoupling current-controller of the power-decoupling buck-boost converter. Therefore, the proposed power decoupling control scheme is cost-effective as well as the size benefit. A new transient analysis is carried out which includes the source voltage dynamics instead of considering the source voltage as a pure voltage source. For verification of the proposed control scheme, simulation and experimental results are presented.