Dynamics Analysis Using Koopman Mode Decomposition of a Microgrid Including Virtual Synchronous Generator-Based Inverters

Yuko Hirase, Yuki Ohara, Naoya Matsuura and Takeaki Yamazaki
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Yuko Hirase: Department of Electrical, Electronic and Communications Engineering, Toyo University, 2100 Kujirai, Kawagoe 350-8585, Japan
Yuki Ohara: Department of Electrical, Electronic and Communications Engineering, Toyo University, 2100 Kujirai, Kawagoe 350-8585, Japan
Naoya Matsuura: Department of Electrical, Electronic and Communications Engineering, Toyo University, 2100 Kujirai, Kawagoe 350-8585, Japan
Takeaki Yamazaki: Department of Electrical, Electronic and Communications Engineering, Toyo University, 2100 Kujirai, Kawagoe 350-8585, Japan

Energies, 2021, vol. 14, issue 15, 1-20

Abstract: In the field of microgrids (MGs), steady-state power imbalances and frequency/voltage fluctuations in the transient state have been gaining prominence owing to the advancing distributed energy resources (DERs) connected to MGs via grid-connected inverters. Because a stable, safe power supply and demand must be maintained, accurate analyses of power system dynamics are crucial. However, the natural frequency components present in the dynamics make analyses complex. The nonlinearity and confidentiality of grid-connected inverters also hinder controllability. The MG considered in this study consisted of a synchronous generator (the main power source) and multiple grid-connected inverters with storage batteries and virtual synchronous generator (VSG) control. Although smart inverter controls such as VSG contribute to system stabilization, they induce system nonlinearity. Therefore, Koopman mode decomposition (KMD) was utilized in this study for consideration as a future method of data-driven analysis of the measured frequencies and voltages, and a frequency response analysis of the power system dynamics was performed. The Koopman operator is a linear operator on an infinite dimensional space, whereas the original dynamics is a nonlinear map on a finite state space. In other words, the proposed method can precisely analyze all the dynamics of the power system, which involve the complex nonlinearities caused by VSGs.

Keywords: data driven analysis; frequency characteristics; Koopman mode; microgrid; nonlinearity; virtual synchronous generator (search for similar items in EconPapers)
JEL-codes: Q Q0 Q4 Q40 Q41 Q42 Q43 Q47 Q48 Q49 (search for similar items in EconPapers)
Date: 2021
References: View references in EconPapers View complete reference list from CitEc
Citations: View citations in EconPapers (1)

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