Control of parallel converters for load sharing with seamless transfer between grid connected and islanded modes

This paper describes control methods for proper load sharing between parallel converters connected to microgrid supplied by distributed generators. The model of the microgrid power system is simulated in PSCAD. It is assumed that the microgrid supplies a load both in grid connected and islanded modes. Both passive loads and inertial loads are considered. A control strategy is proposed to improve the system performance through seamless transfer between islanded and grid connected modes. The controller is capable of handling constant impedance, as well as motor loads. The smooth transition between the grid connected and off grid mode is achieved by changing the control mode from voltage control in islanded mode to state feedback control in grid connected mode. Its efficacy has been validated through simulation for various operating conditions.

[1]  J.-W. Jung,et al.  Power flow control of a single distributed generation unit with nonlinear local load , 2004, IEEE PES Power Systems Conference and Exposition, 2004..

[2]  M.R. Iravani,et al.  Power Management Strategies for a Microgrid With Multiple Distributed Generation Units , 2006, IEEE Transactions on Power Systems.

[3]  J. Miret,et al.  Steady-state invariant-frequency control of parallel redundant uninterruptible power supplies , 2002, IEEE 2002 28th Annual Conference of the Industrial Electronics Society. IECON 02.

[4]  L. van der Sluis,et al.  Dynamic Stability of Power Systems with Power Electronic Interfaced DG , 2006, 2006 IEEE PES Power Systems Conference and Exposition.

[5]  Arindam Ghosh,et al.  A new approach to load balancing and power factor correction in power distribution system , 2000 .

[6]  R. Adapa,et al.  Control of parallel connected inverters in stand-alone AC supply systems , 1991, Conference Record of the 1991 IEEE Industry Applications Society Annual Meeting.

[7]  J. Miret,et al.  A wireless controller to enhance dynamic performance of parallel inverters in distributed generation systems , 2004, IEEE Transactions on Power Electronics.

[8]  R. Iravani,et al.  A Linear Quadratic Gaussian Controller for a Stand-alone Distributed Resource Unit-Simulation Case Studies , 2007, 2007 IEEE Power Engineering Society General Meeting.

[9]  Arindam Ghosh.  Performance study of two different compensating devices in a custom power park , 2005 .

[10]  R.H. Lasseter,et al.  Microgrid: a conceptual solution , 2004, 2004 IEEE 35th Annual Power Electronics Specialists Conference (IEEE Cat. No.04CH37551).