Impedance Matching of Direct Grid-Connected Renewable Energy Synchronous Generators

The connection of synchronous generators directly to renewable energy micro-grids has the advantage of increasing the short circuit strength of the micro-grid. If these generators can also be part of converting renewable energy, such as wind and hydro energy, to electrical power, then it is a further advantage. In this paper the impedance matching of such a directly grid-connected permanent magnet generator, with the grid subjected to power and grid voltage variability, is investigated. It is shown that the optimum reactance for best impedance matching is 0.5 per unit at an optimum induced back electromotive force (EMF) voltage of 1.05 per unit. Additionally, laboratory testing of a direct-grid connected permanent magnet synchronous generator is conducted and its performance evaluated for varying grid voltages and input power conditions.

[1]  M. J. Kamper,et al.  Design and optimisation of grid compliant variable-flux PM synchronous generator for wind turbine applications , 2015, 2015 IEEE Energy Conversion Congress and Exposition (ECCE).

[2]  B. Singh,et al.  Multifunctional capabilities of converter interfaced distributed resource in grid connected mode , 2012, 2012 IEEE 5th India International Conference on Power Electronics (IICPE).

[3]  J. H. J. Potgieter,et al.  Design of New Concept Direct Grid-Connected Slip-Synchronous Permanent-Magnet Wind Generator , 2012, IEEE Transactions on Industry Applications.

[4]  G. Joós,et al.  Transient Modeling and Comparison of Wind Generator Topologies , 2005 .

[5]  Jan Svec,et al.  Optimal location of the synchronous condenser in electric-power system networks , 2016, 2016 17th International Scientific Conference on Electric Power Engineering (EPE).

[6]  Miroslaw Parol,et al.  Voltage stability in low voltage microgrids in aspects of active and reactive power demand , 2016 .

[7]  P ? ? ? ? ? ? ? % ? ? ? ? , 1991 .

[8]  Eduard Muljadi,et al.  Short circuit current contribution for different wind turbine generator types , 2010, IEEE PES General Meeting.

[10]  Tsuyoshi Murata,et al.  {m , 1934, ACML.

[11]  C. Marnay,et al.  Shape of the microgrid , 2000, 2001 IEEE Power Engineering Society Winter Meeting. Conference Proceedings (Cat. No.01CH37194).

[12]  D. K. Jain,et al.  Power system stability analysis with large penetration of distributed generation , 2014, 2014 6th IEEE Power India International Conference (PIICON).

[13]  J. Pyrhonen,et al.  Hybrid excitation synchronous generators for small hydropower plants , 2016, 2016 XXII International Conference on Electrical Machines (ICEM).

[14]  Vahan Gevorgian,et al.  Synchronous Condenser Allocation for Improving System Short Circuit Ratio , 2018, 2018 5th International Conference on Electric Power and Energy Conversion Systems (EPECS).

[15]  Il-Yop Chung,et al.  Control Methods of Inverter-Interfaced Distributed Generators in a Microgrid System , 2010, IEEE Transactions on Industry Applications.

[16]  S. Perera,et al.  Dynamic characteristics of a hybrid microgrid with inverter and non- inverter interfaced renewable energy sources: A case study , 2012, 2012 IEEE International Conference on Power System Technology (POWERCON).

[17]  G. G. Stokes.  "J." , 1890, The New Yale Book of Quotations.

[18]  A. Gavrilovic,et al.  AC/DC system strength as indicated by short circuit ratios , 1991 .