• Title/Summary/Keyword: PCS(Single-phase Power Conditioning System)

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Characteristics of Utility Transformer on Household Single-Phase ESS-PCS According to LC Filter Location (주택용 단상 ESS-PCS의 LC 필터위치에 따른 상용변압기의 특성)

  • Kim, Yong-Jung;Kim, Hyosung
    • The Transactions of the Korean Institute of Power Electronics
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    • v.23 no.2
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    • pp.101-105
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    • 2018
  • Shortage of electric power occurs frequently along with increased electric power demand. ESS is a precaution to solve this issue. Household ESS has a capacity of approximately 3 kW/7 kWh. Household ESS batteries are typically designed with nominal voltages between 40 and 50 V. To connect household ESS with a 220 V AC system, low battery voltages in power conditioning system (PCS) should be boosted. To boost low battery voltage and match it with AC grid voltage, the use of a transformer for a commercial frequency can be considered. To attenuate switching harmonics of the household single-phase ESS-PCS, LC filter can be installed in two positions: on the primary side or on the secondary side of a transformer. A method has been used generally in single-phase inverters for the ESS-PCS. In another method, however, the output efficiency of the ESS-PCS may be decreased. Parasitic components of the transformer can affect voltage losses, when the square wave with the switching frequency in the ESS-PCS is passed through the transformer windings. In this work, the characteristics of the transformer according to the position of an LC filter are investigated for household single-phase ESS-PCS.

High-Efficiency Power Conditioning System for Grid-Connected Photovoltaic Modules

  • Choi, Woo-Young;Choi, Jae-Yeon
    • Journal of Power Electronics
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    • v.11 no.4
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    • pp.561-567
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    • 2011
  • This paper presents a high-efficiency power conditioning system (PCS) for grid-connected photovoltaic (PV) modules. The proposed PCS consists of a step-up DC-DC converter and a single-phase DC-AC inverter for the grid-connected PV modules. A soft-switching step-up DC-DC converter is proposed to generate a high DC-link voltage from the low PV module voltage with a high-efficiency. A DC-link voltage controller is presented for constant DC-link voltage regulation. A half-bridge inverter is used for the single-phase DC-AC inverter for grid connection. A grid current controller is suggested to supply PV electrical power to the power grid with a unity power factor. Experimental results are obtained from a 180 W grid-connected PV module system using the proposed PCS. The proposed PCS achieves a high power efficiency of 93.0 % with an unity power factor for a 60 Hz / 120 Vrms AC power grid.

Design and Implementation of Photovoltaic Power Conditioning System using a Current-based Maximum Power Point Tracking

  • Lee, Sang-Hoey;Kim, Jae-Eon;Cha, Han-Ju
    • Journal of Electrical Engineering and Technology
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    • v.5 no.4
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    • pp.606-613
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    • 2010
  • This paper proposes a novel current-based maximum power point tracking (CMPPT) method for a single-phase photovoltaic power conditioning system (PV PCS) by using a modified incremental conductance method. The CMPPT method simplifies the entire control structure of the power conditioning system and uses an inherent current source characteristic of solar cell arrays. Therefore, it exhibits robust and fast response under a rapidly changing environmental condition. Digital phase locked loop technique using an all-pass filter is also introduced to detect the phase of grid voltage, as well as the peak voltage. Controllers of dc/dc boost converter, dc-link voltage, and dc/ac inverter are designed for coordinated operation. Furthermore, a current control using a pseudo synchronous d-q transformation is employed for grid current control with unity power factor. A 3 kW prototype PV PCS is built, and its experimental results are given to verify the effectiveness of the proposed control schemes.

Design of DC Battery Size & Controller for Household Single-Phase ESS-PCS Considering Voltage Drop and DC Link Voltage Ripple (주택용 단상 ESS-PCS의 전압손실과 직류링크 맥동을 고려한 직류측 배터리 사이즈 및 제어기 설계)

  • Kim, Yong-Jung;Lee, Jinsung;Kim, Hyosung
    • The Transactions of the Korean Institute of Power Electronics
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    • v.23 no.2
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    • pp.94-100
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    • 2018
  • Generally, in a single-phase energy storage system (ESS) for households, AC ripple component with twice the fundamental frequency exists inevitably in the DC link voltage of single-phase PCS. In the grid-connected mode of a single-phase inverter, the AC ripple component in the DC link voltage causes low-order harmonics on grid-side current that deteriorates power quality on an AC grid. In this work, a control system adopting a feedforward controller is established to eliminate the AC ripple interference on the DC link side. Optimal battery nominal voltage design method is also proposed by considering the voltage loss and AC ripple voltage on DC link side in a single-phase ESS. Finally, the control system and battery nominal voltage design method are verified through simulations and experiments.

New PCS Applied High Boost Ratio Dual Converter and Single Phase Half Bridge Inverter (고승압 듀얼 컨버터와 단상 하프 브릿지 인버터를 적용한 새로운 PCS)

  • Lee, Hee-Jun;Shin, Soo-Choel;Hyun, Seung-Wook;Jung, Yong-Chae;Won, Chung-Yuen
    • The Transactions of the Korean Institute of Power Electronics
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    • v.18 no.6
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    • pp.515-522
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    • 2013
  • In this paper, a new PCS is proposed which is consisted of high boost dual converter and single phase half-bridge inverter. The proposed PCS is configured in parallel input / serial output, using two interleaved voltage doubler converter. Converter of the proposed PCS is distribute input current by configuring parallel input and reduced turn ratio of transformer by configuring serial output. Also, compositions of the inverter are composed of serial output capacitor of converter and half-bridge inverter. The dual converter and single phase half-bridge inverter is designed and characteristic of the new PCS is analysed. The system of the 1.5[kW] PCS is verified through an experimental about operation and stability.

Operational Characteristic Analysis of a Single-Phase PCS for PV Power Generation System with Active Filter Function (엑티브 필터 기능을 가지는 단상 태양광 PCS의 운전특성 해석)

  • Jang, Seong-Jae;Seo, Hyo-Ryong;Kim, Gyeong-Hun;Park, Sang-Soo;Kim, Sang-Yong;Park, Min-Won;Yu, In-Keun
    • Proceedings of the KIEE Conference
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    • 2009.07a
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    • pp.1051_1052
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    • 2009
  • This paper deals with operational characteristic analysis of a single-phase PCS (Power Conditioning System) for PV (Photovoltaic) power generation system with AF (Active Filter) function. The theory of dq transformation has been applied to the control strategy of a single-phase PV power generation system to implement the AF function. Application of the virtual two-phase using phase-shift makes it possible to use the dq theory for the single-phase PV power generation system. The authors are sure that the proposed system is a very useful to compensate harmonics caused by nonlinear loads in a single-phase utility system. In this paper, not only a theoretical aspect of the single-phase PV-AF system is discussed, but also the DSP (Digital Signal Processor) based experiment results are presented to demonstrate the effectiveness of the single-phase PV-AF system.

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Transformerless Three-Phase Line-connected Photovoltaic PCS (무변압기형 3상 계통연계 PV PCS)

  • Seo, Hyun-Woo;Kwon, Jung-Min;Kwon, Bong-Hwan
    • The Transactions of the Korean Institute of Power Electronics
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    • v.12 no.5
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    • pp.355-363
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    • 2007
  • In this paper, the transformerless three-phase line-connected PV PCS (photovoltaic power conditioning system) is proposed. An improved P&O (perturb and observe) MPPT (maximum power point tracking) algorithm that prevents local maximum power point tracking is proposed. By controlling the three-phase line-connected voltage source inverter using outer DC-link voltage controller, inner current controller and microcontroller friendly simplified space vector modulation (SVM) method, a unity power factor is achieved. An algorithm is suggested to control the DC-link voltage faster and more correctly for the increase system stability and power factor. All algorithms and controllers are implemented on a single-chip microcontroller and the superiority of the proposed algorithms and controllers is proved by experiments.

New MPPT Control Strategy for Two-Stage Grid-Connected Photovoltaic Power Conditioning System

  • Bae, Hyun-Su;Park, Joung-Hu;Cho, Bo-Hyung;Yu, Gwon-Jong
    • Journal of Power Electronics
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    • v.7 no.2
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    • pp.174-180
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    • 2007
  • In this paper, a simple control method for two-stage utility grid-connected photovoltaic power conditioning systems (PCS) is proposed. This approach enables maximum power point (MPP) tracking control with post-stage inverter current information instead of calculating solar array power, which significantly simplifies the controller and the sensor. Furthermore, there is no feedback loop in the pre-stage converter to control the solar array voltage or current because the MPP tracker drives the converter switch duty cycle. This simple PCS control strategy can reduce the cost and size, and can be utilized with a low cost digital processor. For verification of the proposed control strategy, a 2.5kW two-stage photovoltaic grid-connected PCS hardware which consists of a boost converter cascaded with a single-phase inverter was built and tested.

Power Loss Analysis of Interleaved Soft Switching Boost Converter for Single-Phase PV-PCS

  • Kim, Jae-Hyung;Jung, Yong-Chae;Lee, Su-Won;Lee, Tae-Won;Won, Chung-Yuen
    • Journal of Power Electronics
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    • v.10 no.4
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    • pp.335-341
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    • 2010
  • In this paper, an interleaved soft switching boost converter for a Photovoltaic Power Conditioning System (PV-PCS) with high efficiency is proposed. In order to raise the efficiency of the proposed converter, a 2-phase interleaved boost converter integrated with soft switching cells is used. All of the switching devices in the proposed converter achieve zero current switching (ZCS) or zero voltage switching (ZVS). Thus, the proposed circuit has a high efficiency characteristic due to low switching losses. To analyze the power losses of the proposed converter, two experimental sets have been built. One consists of normal devices (MOSFETs, Fast Recovery (FR) diodes) and the other consists of advanced power devices (CoolMOSs, SiC-Schottky Barrier Diodes (SBDs)). To verify the validity of the proposed topology, theoretical analysis and experimental results are presented.

The Notch Filter Design for Mitigation Current Ripple of Fuel cell-PCS (연료전지용 PCS의 출력 전류 리플 개선을 위한 노치 필터 설계)

  • Kim, Seung-Min;Park, Bong-Hee;Choi, Ju-Yeop;Choy, Ick;Lee, Sang-Chul;Lee, Dong-Ha
    • Journal of the Korean Solar Energy Society
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    • v.32 no.6
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    • pp.106-112
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    • 2012
  • As a fuel cell converts the chemical energy of the fuel cell into electrical energy by electrochemical reaction, the fuel cell system is uniquely integrated technique including fuel processor, fuel cell stack, power conditioning system. The residential fuel cell-PCS(Power Conditioning System) needs to convert efficiently the DC current produced by the fuel cell into AC current using single-phase DC-AC inverter. A single-phase DC-AC inverter has naturally low frequency ripple which is twice frequency of the output current. This low frequency(120Hz) ripple reduces the efficiency of the fuel cell. This paper presents notch filter with IP voltage controller to reject specific 120Hz current ripple in single-phase inverter. The notch filter is designed that suppress just only specific frequency component and no phase delay. Finally, the proposed notch filter design method has been verified with computer simulation and experimentation.