Efficient single phase transformerless inverter for grid tied pvg system with reactive power control
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This document describes a proposed transformer-less inverter topology for grid-tied photovoltaic systems. The existing dual-parallel buck converter topology has issues where the grid can short circuit if there is no dead time between switches. The proposed topology addresses this by using six MOSFET switches and six diodes in a configuration that allows reactive power injection while overcoming reliability issues. It has advantages like utilizing only MOSFET switches, low leakage current, and not requiring PWM dead times. The proposed single-phase inverter is intended for grid-tied PV applications.
Efficient single phase transformerless inverter for grid tied pvg system with reactive power control
- 1. The Master of IEEE Projects Copyright © 2016LeMenizInfotech. All rights reserved LeMenizInfotech 36, 100 Feet Road, Natesan Nagar, Near Indira Gandhi Statue, Pondicherry-605 005. Call: 0413-4205444, +91 9566355386, 99625 88976. Web :www.lemenizinfotech.com/ www.ieeemaster.com Mail : projects@lemenizinfotech.com Efficient Single Phase Transformer less Inverter for Grid-Tied PVG System with Reactive Power Control Introduction: In general, PV power generation system includes solar arrays and power conversion unit. In most countries and areas, a line-frequency transformer or a high-frequency transformer has been utilized in the grid-tied PV system to create a galvanic isolation between the PV module and the grid. However, the use of line-frequency or high- frequency transformer makes the entire system bulky, costly, and less efficient. In contrast, transformer less PV inverter system has been drawing more attention for its low cost, high efficiency, small size and light weight. The exclusion of transformer, and hence its isolation capability, has to be considered carefully due to the issues raised from no galvanic isolation between the PV module and the grid. In this case, because of the parasitic capacitance between the PV module and the ground, the fluctuating CM voltage that depends on the topology structure and switching scheme can cause of a capacitive leakage current. The existence of leakage current increases grid current harmonics and system losses, deteriorates the electromagnetic compatibility and, more significantly, lead to a safety threat. Existing system: Dual-parallel- buck converter, consists of four Cool MOS switches and four SiC diodes. The main drawback of this topology is that the grid will be short circuit if no dead time is present between the switches S3 and S4, through which the grid is directly connected. The main
- 2. The Master of IEEE Projects Copyright © 2016LeMenizInfotech. All rights reserved LeMenizInfotech 36, 100 Feet Road, Natesan Nagar, Near Indira Gandhi Statue, Pondicherry-605 005. Call: 0413-4205444, +91 9566355386, 99625 88976. Web :www.lemenizinfotech.com/ www.ieeemaster.com Mail : projects@lemenizinfotech.com advantage of these two topologies is that when a phase difference will be occurred between the output voltage and current, the diodes D1 & D2 or D3 & D4 will be activated depending on the positive or negative half cycle. As a result, these topologies may be implemented with MOSFET switches even when inject reactive power. Drawbacks: The grid will be short circuit if no dead time is present between the switches S3 and S4, through which the grid is directly connected. Proposed system: The proposed transformer less inverter topology consists of six MOSFET switches (S1-S6) and six diodes (D1-D6). L1A, L1B, L2A, L2B, L1g, L2g and Co make up the LCL type filter connected to the grid. VPV and Cdc represent the input dc voltage and dc link capacitor. The proposed topology is derived overcome the low reverse-recovery issues of MOSFETs body-diode when injects reactive power into the utility grid. Therefore, the proposed topology can be implemented with MOSFET switches without reliability and efficiency penalty. The
- 3. The Master of IEEE Projects Copyright © 2016LeMenizInfotech. All rights reserved LeMenizInfotech 36, 100 Feet Road, Natesan Nagar, Near Indira Gandhi Statue, Pondicherry-605 005. Call: 0413-4205444, +91 9566355386, 99625 88976. Web :www.lemenizinfotech.com/ www.ieeemaster.com Mail : projects@lemenizinfotech.com proposed topology can also employ unipolar-SPWM with three-level output voltage. Advantages: Utilizing MOSFET switches even though when inject reactive power into the utility grid. Low leakage current flows through the system PWM dead time is not required for the proposed topology that reduces the THD at the output. Applications: Grid-tied PV system.
- 4. The Master of IEEE Projects Copyright © 2016LeMenizInfotech. All rights reserved LeMenizInfotech 36, 100 Feet Road, Natesan Nagar, Near Indira Gandhi Statue, Pondicherry-605 005. Call: 0413-4205444, +91 9566355386, 99625 88976. Web :www.lemenizinfotech.com/ www.ieeemaster.com Mail : projects@lemenizinfotech.com Block diagram: Solar supply Transformer less inverter LoadCoupled inductor Micro-controller circuit Buffer circuit Driver circuit 5V DC Supply 12V DC