High-Fidelity Model Order Reduction for Microgrids Stability Assessment

Proper modeling of inverter-based microgrids is crucial for accurate assessment of stability boundaries. It has been recently realized that the stability conditions for such microgrids are significantly different from those known for large-scale power systems. In particular, the network dynamics, despite its fast nature, appears to have major influence on stability of slower modes. While detailed models are available, they are both computationally expensive and not transparent enough to provide an insight into the instability mechanisms and factors. In this paper, a computationally efficient and accurate reduced-order model is proposed for modeling inverter-based microgrids. The developed model has a structure similar to quasi-stationary model and at the same time properly accounts for the effects of network dynamics. The main factors affecting microgrid stability are analyzed using the developed reduced-order model and shown to be unique for microgrids, having no direct analogy in large-scale power systems. Particularly, it has been discovered that the stability limits for the conventional droop-based system are determined by the ratio of inverter rating to network capacity, leading to a smaller stability region for microgrids with shorter lines. Finally, the results are verified with different models based on both frequency and time domain analyses.

[1]  E.F. El-Saadany,et al.  Adaptive Decentralized Droop Controller to Preserve Power Sharing Stability of Paralleled Inverters in Distributed Generation Microgrids , 2008, IEEE Transactions on Power Electronics.

[2]  Hossein Lotfi,et al.  State of the Art in Research on Microgrids: A Review , 2015, IEEE Access.

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

[4]  Josep M. Guerrero,et al.  Dynamic Phasors-Based Modeling and Stability Analysis of Droop-Controlled Inverters for Microgrid Applications , 2014, IEEE Transactions on Smart Grid.

[5]  Yun Wei Li,et al.  Analysis, Design, and Implementation of Virtual Impedance for Power Electronics Interfaced Distributed Generation , 2011, IEEE Transactions on Industry Applications.

[6]  Jonathan W. Kimball,et al.  Reduced-Order Small-Signal Model of Microgrid Systems , 2015, IEEE Transactions on Sustainable Energy.

[7]  N. Yorino,et al.  An interaction problem of distributed generators installed in a MicroGrid , 2004, 2004 IEEE International Conference on Electric Utility Deregulation, Restructuring and Power Technologies. Proceedings.

[8]  Timothy C. Green,et al.  Dynamic Stability of a Microgrid With an Active Load , 2013, IEEE Transactions on Power Electronics.

[9]  M. Smith,et al.  Key Connections: The U.S. Department of Energy?s Microgrid Initiative , 2013 .

[10]  Josep M. Guerrero,et al.  Mode Adaptive Droop Control With Virtual Output Impedances for an Inverter-Based Flexible AC Microgrid , 2011, IEEE Transactions on Power Electronics.

[11]  S. Iyer,et al.  A Generalized Computational Method to Determine Stability of a Multi-inverter Microgrid , 2010, IEEE Transactions on Power Electronics.

[12]  Yun Zhang,et al.  Interactive Control of Coupled Microgrids for Guaranteed System-Wide Small Signal Stability , 2016, IEEE Transactions on Smart Grid.

[13]  Qing-Chang Zhong,et al.  Synchronverters: Inverters That Mimic Synchronous Generators , 2011, IEEE Transactions on Industrial Electronics.

[14]  Frede Blaabjerg,et al.  Virtual-Impedance-Based Control for Voltage-Source and Current-Source Converters , 2015, IEEE Transactions on Power Electronics.

[15]  Francesco Vasca,et al.  Model Order Reductions for Stability Analysis of Islanded Microgrids With Droop Control , 2015, IEEE Transactions on Industrial Electronics.

[16]  Nikos D. Hatziargyriou,et al.  Microgrids : architectures and control , 2014 .

[17]  Yun Zhang,et al.  Online Dynamic Security Assessment of Microgrid Interconnections in Smart Distribution Systems , 2015, IEEE Transactions on Power Systems.

[18]  Janusz Bialek,et al.  Power System Dynamics: Stability and Control , 2008 .

[19]  Josep M. Guerrero,et al.  Advanced Control Architectures for Intelligent Microgrids—Part I: Decentralized and Hierarchical Control , 2013, IEEE Transactions on Industrial Electronics.

[20]  Enrique Romero-Cadaval,et al.  Grid-Connected Photovoltaic Generation Plants: Components and Operation , 2013, IEEE Industrial Electronics Magazine.

[21]  Ritwik Majumder,et al.  Some Aspects of Stability in Microgrids , 2013, IEEE Transactions on Power Systems.

[22]  M. Smith,et al.  Key Connections: The U.S. Department of Energy?s Microgrid Initiative , 2012, IEEE Power and Energy Magazine.

[23]  Florian Dörfler,et al.  Droop-Controlled Inverters are Kuramoto Oscillators , 2012, ArXiv.

[24]  Sairaj V. Dhople,et al.  Spatiotemporal Model Reduction of Inverter-Based Islanded Microgrids , 2014, IEEE Transactions on Energy Conversion.

[25]  Hatem H. Zeineldin,et al.  Stability Evaluation of Interconnected Multi-Inverter Microgrids Through Critical Clusters , 2016, IEEE Transactions on Power Systems.

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

[27]  Mike Barnes,et al.  Stability of a MicroGrid , 2006 .

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

[29]  Bill Rose,et al.  Microgrids , 2018, Smart Grids.

[30]  Jon Andreu,et al.  General aspects, hierarchical controls and droop methods in microgrids: A review , 2013 .

[31]  Juan C. Vasquez,et al.  Hierarchical Control of Droop-Controlled AC and DC Microgrids—A General Approach Toward Standardization , 2009, IEEE Transactions on Industrial Electronics.

[32]  Ernane Antônio Alves Coelho,et al.  Small signal stability for parallel connected inverters in stand-alone AC supply systems , 2000 .

[33]  Oriol Gomis-Bellmunt,et al.  Trends in Microgrid Control , 2014, IEEE Transactions on Smart Grid.

[34]  Josep M. Guerrero,et al.  Output impedance design of parallel-connected UPS inverters with wireless load-sharing control , 2005, IEEE Transactions on Industrial Electronics.

[35]  Ernane Antônio Alves Coelho,et al.  Small signal stability for parallel connected inverters in stand-alone AC supply systems , 2000, Conference Record of the 2000 IEEE Industry Applications Conference. Thirty-Fifth IAS Annual Meeting and World Conference on Industrial Applications of Electrical Energy (Cat. No.00CH37129).

[36]  Juan C. Vasquez,et al.  An Islanding Microgrid Power Sharing Approach Using Enhanced Virtual Impedance Control Scheme , 2013, IEEE Transactions on Power Electronics.

[37]  Xu Rong,et al.  A review on distributed energy resources and MicroGrid , 2008 .

[38]  Robert Lasseter,et al.  Smart Distribution: Coupled Microgrids , 2011, Proceedings of the IEEE.

[39]  Josep M. Guerrero,et al.  Design and Analysis of the Droop Control Method for Parallel Inverters Considering the Impact of the Complex Impedance on the Power Sharing , 2011, IEEE Transactions on Industrial Electronics.

[40]  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.