Islanded-Mode Control of Electronically Coupled Distributed-Resource Units Under Unbalanced and Nonlinear Load Conditions

This paper proposes a voltage- and frequency-control strategy for the islanded operation of dispatchable electronically coupled distributed-resource units, based on a discrete-time mathematical model which is also valid for variable-frequency operation. The proposed control strategy utilizes a combination of deadbeat and repetitive control to enhance the performance of the control system under unbalanced and/or distorted load currents. Moreover, a new approach is proposed to maintain the effectiveness of the repetitive control under variable-frequency operational scenarios. Furthermore, the control strategy employs feedforward compensation techniques to mitigate the impact of load dynamics on the regulation process. The performance of the proposed control strategy is demonstrated for single- and multiunit islanded networks, through digital time-domain simulation studies in the PSCAD/EMTDC software environment.

[1]  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.

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

[3]  Reza Iravani,et al.  Control of an Electronically-Coupled Distributed Resource Unit Subsequent to an Islanding Event , 2008 .

[4]  P.W. Lehn,et al.  Control and Power Management of Converter Fed Microgrids , 2008, IEEE Transactions on Power Systems.

[5]  P.W. Lehn,et al.  Autonomous load sharing of voltage source converters , 2005, IEEE Transactions on Power Delivery.

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

[7]  Gunnar Hillerstrom,et al.  Adaptive suppression of vibrations - a repetitive control approach , 1996, IEEE Trans. Control. Syst. Technol..

[8]  Unto K. Laine,et al.  Splitting the unit delay [FIR/all pass filters design] , 1996, IEEE Signal Process. Mag..

[9]  Se-Kyo Chung,et al.  A phase tracking system for three phase utility interface inverters , 2000 .

[10]  P.W. Lehn,et al.  Intentional islanded operation of converter fed microgrids , 2006, 2006 IEEE Power Engineering Society General Meeting.

[11]  Maarten Steinbuch,et al.  Repetitive control for systems with uncertain period-time , 2002, Autom..

[12]  J. Driesen,et al.  Design for distributed energy resources , 2008, IEEE Power and Energy Magazine.

[13]  Masayoshi Tomizuka,et al.  Steady-State and Stochastic Performance of a Modified Discrete-Time Prototype Repetitive Controller , 1990 .

[14]  C. B. Cooper,et al.  IEEE Recommended Practice for Electric Power Distribution for Industrial Plants , 1987 .

[15]  Charles Sao,et al.  Control and Power Management of Converter Fed Microgrids , 2008 .

[16]  K. Srinivasan,et al.  Discrete-Time Repetitive Control System Design Using the Regeneration Spectrum , 1993 .

[17]  W. Wonham,et al.  The internal model principle for linear multivariable regulators , 1975 .

[18]  Takao Kawabata,et al.  Dead beat control of three phase PWM inverter , 1987 .

[19]  Poh Chiang Loh,et al.  Design, analysis, and real-time testing of a controller for multibus microgrid system , 2004, IEEE Transactions on Power Electronics.

[20]  G. Oetken.  A new approach for the design of digital interpolating filters , 1979 .

[21]  A. Yazdani.  Control of an islanded Distributed Energy Resource unit with load compensating feed-forward , 2008, 2008 IEEE Power and Energy Society General Meeting - Conversion and Delivery of Electrical Energy in the 21st Century.

[22]  P.W. Lehn,et al.  Voltage balancing of converter fed microgrids with single phase loads , 2008, 2008 IEEE Power and Energy Society General Meeting - Conversion and Delivery of Electrical Energy in the 21st Century.