Control Methods of Inverter-Interfaced Distributed Generators in a Microgrid System

Microgrids are a new concept for future energy distribution systems that enable renewable energy integration and improved energy management capability. Microgrids consist of multiple distributed generators (DGs) that are usually integrated via power electronic inverters. In order to enhance power quality and power distribution reliability, microgrids need to operate in both grid-connected and island modes. Consequently, microgrids can suffer performance degradation as the operating conditions vary due to abrupt mode changes and variations in bus voltages and system frequency. This paper presents controller design and optimization methods to stably coordinate multiple inverter-interfaced DGs and to robustly control individual interface inverters against voltage and frequency disturbances. Droop-control concepts are used as system-level multiple DG coordination controllers, and control theory is applied to device-level inverter controllers. Optimal control parameters are obtained by particle-swarm-optimization algorithms, and the control performance is verified via simulation studies.

[1]  P. Kundur,et al.  Power system stability and control , 1994 .

[2]  Deepak Divan,et al.  Control of distributed UPS systems , 1994, Proceedings of 1994 Power Electronics Specialist Conference - PESC'94.

[3]  E. Collins,et al.  Robust l/sub 1/ design of a multivariable PI controller using a real-coded genetic algorithm , 2005, Proceedings of the 2005, American Control Conference, 2005..

[4]  M. B. Brennen,et al.  Vector analysis and control of advanced static VAr compensators , 1991 .

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

[6]  T.C. Green,et al.  Energy Management in Autonomous Microgrid Using Stability-Constrained Droop Control of Inverters , 2008, IEEE Transactions on Power Electronics.

[7]  Il-Yop Chung,et al.  A New Islanding Detection Method using Phase-Locked Loop for Inverter-Interfaced Distributed Generators , 2007 .

[8]  M. Krstic,et al.  Auto-tuning of PID controllers via extremum seeking , 2005, Proceedings of the 2005, American Control Conference, 2005..

[9]  E. Yaz,et al.  Linear optimal control, H2 and H∞ methods, by Jeffrey B. Burl, Addison Wesley Longman, Inc. Menlo Park, CA, 1999 , 2000 .

[10]  N. Hatziargyriou,et al.  Microgrids: an overview of ongoing research, development, anddemonstration projects , 2007 .

[11]  Il-Yop Chung,et al.  Operating strategy and control scheme of premium power supply interconnected with electric power systems , 2005 .

[12]  James Kennedy,et al.  Particle swarm optimization , 2002, Proceedings of ICNN'95 - International Conference on Neural Networks.

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

[14]  W. Haddad,et al.  Mixed-norm H2/L1 controller synthesis via fixed-order dynamic compensation: A Riccati equation approach , 1998 .

[15]  Il-Yop Chung,et al.  Integration of a bi-directional dc-dc converter model into a large-scale system simulation of a shipboard MVDC power system , 2009, 2009 IEEE Electric Ship Technologies Symposium.

[16]  P.W. Lehn,et al.  Micro-grid autonomous operation during and subsequent to islanding process , 2005, IEEE Transactions on Power Delivery.

[17]  Mathukumalli Vidyasagar,et al.  Optimal rejection of persistent bounded disturbances , 1986 .

[18]  Y. Rahmat-Samii,et al.  Particle swarm optimization in electromagnetics , 2004, IEEE Transactions on Antennas and Propagation.

[19]  Poh Chiang Loh,et al.  Robust Control Scheme for a Microgrid With PFC Capacitor Connected , 2007, IEEE Transactions on Industry Applications.

[20]  Wassim M. Haddad,et al.  Fixed-order dynamic compensation for linear systems with actuator amplitude and rate saturation constraints , 2000 .

[21]  Il-Yop Chung,et al.  Control parameter optimization for a microgrid system using particle swarm optimization , 2008, 2008 IEEE International Conference on Sustainable Energy Technologies.

[22]  T.C. Green,et al.  Modeling, Analysis and Testing of Autonomous Operation of an Inverter-Based Microgrid , 2007, IEEE Transactions on Power Electronics.

[23]  Wassim M. Haddad,et al.  Mixed-norm H/sub 2//L/sub 1/ controller synthesis via fixed-order dynamic compensation: a Riccati equation approach , 1997, Proceedings of the 36th IEEE Conference on Decision and Control.