Evaluation of Three-Phase Transformerless Photovoltaic Inverter Topologies

This paper analyzes and compares three transformerless photovoltaic inverter topologies for three-phase grid connection with the main focus on the safety issues that result from the lack of galvanic isolation. A common-mode model, valid at frequencies lower than 50 kHz, is adopted to study the leakage current paths. The model is validated by both simulation and experimental results. These will be used to compare the selected topologies, and to explain the influence of system unbalance and the neutral conductor inductance on the leakage current. It will be demonstrated that the later has a crucial influence. Finally, a comparison of the selected topologies is carried out, based on the adopted modulation, connection of the neutral and its inductance, effects of unbalance conditions, component ratings, output voltage levels, and filter size.

[1]  J. H. Alimeling,et al.  PLECS-piece-wise linear electrical circuit simulation for Simulink , 1999, Proceedings of the IEEE 1999 International Conference on Power Electronics and Drive Systems. PEDS'99 (Cat. No.99TH8475).

[2]  V. Agarwal,et al.  A Single-Stage Grid Connected Inverter Topology for Solar PV Systems With Maximum Power Point Tracking , 2007, IEEE Transactions on Power Electronics.

[3]  Frede Blaabjerg,et al.  Implementation and test of an online embedded grid impedance estimation technique for PV inverters , 2005, IEEE Transactions on Industrial Electronics.

[4]  M. Veerachary,et al.  Reliability Issues in Photovoltaic Power Processing Systems , 2008, IEEE Transactions on Industrial Electronics.

[5]  S. Bernet,et al.  Design and comparison of medium voltage multi-level converters for industry applications , 2004, Conference Record of the 2004 IEEE Industry Applications Conference, 2004. 39th IAS Annual Meeting..

[6]  Chung-Yuen Won,et al.  Analysis of a new PWM method for conducted EMI reduction in a field oriented controlled induction motor , 2006, Twenty-First Annual IEEE Applied Power Electronics Conference and Exposition, 2006. APEC '06..

[7]  M. Liserre,et al.  Stability of photovoltaic and wind turbine grid-connected inverters for a large set of grid impedance values , 2006, IEEE Transactions on Power Electronics.

[8]  P. Sanchis,et al.  Transformerless Inverter for Single-Phase Photovoltaic Systems , 2007, IEEE Transactions on Power Electronics.

[9]  U. Borup,et al.  Transformerless Photovoltaic Inverters Connected to the Grid , 2007, APEC 07 - Twenty-Second Annual IEEE Applied Power Electronics Conference and Exposition.

[10]  Roberto González,et al.  Transformerless Single-Phase Multilevel-Based Photovoltaic Inverter , 2008, IEEE Transactions on Industrial Electronics.

[11]  Marco Liserre,et al.  An Anti-Islanding Method for Single-Phase Inverters Based on a Grid Voltage Sensorless Control , 2006, IEEE Transactions on Industrial Electronics.

[12]  M. Liserre,et al.  Design and control of an LCL-filter based three-phase active rectifier , 2001, Conference Record of the 2001 IEEE Industry Applications Conference. 36th IAS Annual Meeting (Cat. No.01CH37248).

[13]  Vassilios G. Agelidis,et al.  Multilevel converters for single-phase grid connected photovoltaic systems-an overview , 1998, IEEE International Symposium on Industrial Electronics. Proceedings. ISIE'98 (Cat. No.98TH8357).

[14]  Pablo Sanchis,et al.  Ground currents in single-phase transformerless photovoltaic systems , 2007 .

[15]  Hirofumi Akagi,et al.  A New Neutral-Point-Clamped PWM Inverter , 1981, IEEE Transactions on Industry Applications.

[16]  Mark Sumner,et al.  Neutral point control for multi-level inverters: theory, design and operational limitations , 1997, IAS '97. Conference Record of the 1997 IEEE Industry Applications Conference Thirty-Second IAS Annual Meeting.

[17]  Ying-Yu Tzou,et al.  Digital Control of a Multi-Phase Interleaved PWM Inverter with Minimal Total Harmonic Distortion , 2007, 2007 IEEE Power Electronics Specialists Conference.

[18]  D. Boroyevich,et al.  Capacitor Voltage Balance for the Neutral-Point- Clamped Converter using the Virtual Space Vector Concept With Optimized Spectral Performance , 2007, IEEE Transactions on Power Electronics.