Sequential Design of Decentralized Robust Controllers for Strongly Interconnected Inverter-Based Distributed Generation Systems: A Comparative Study versus Independent Design

Document Type

Article

Publication Date

12-1-2022

Abstract

Internal oscillations among multiple generation systems in low-voltage stand-alone nanogrids and small-scale microgrids can cause instability in the entire generation system. This issue becomes worse when the coupling strength between the generation systems increases, which is a result of a shorter distance between them and a smaller reactance to resistance ratio. Previous approaches, which were based on the independent control design and considered the coupling effect as disturbances, may fail to tackle this issue when the two generation systems become strongly coupled. Therefore, in this paper a novel method is proposed to handle this coupling effect by designing robust decentralized controllers in a sequential manner to address the problem of voltage and frequency control in a nanogrid. This proposed sequential design is a general technique that is applicable to multiple inverter-based generation systems in a nanogrid or small-scale microgrid. For the ease of demonstration, in this paper the case of two interconnected inverters with LC output filters is studied. Two robust decentralized controllers are designed for the two inverter systems by using the (Formula presented.) -synthesis technique. The sequential design takes into account the interconnection line between the two inverters. Moreover, the controllers are designed to be robust against all the parameter variations in the system including the LC filter and interconnection line parameters. The simulation results demonstrate the superior performance of the proposed controller over the independently-designed controllers for the case of two generation systems that are highly coupled due to the short distance between them. Moreover, the proposed controller is shown to be robust against the LC filter and interconnection line parameter uncertainties as compared to the sequentially-designed linear quadratic Gaussian controllers.

Identifier

85143730565 (Scopus)

Publication Title

Energies

External Full Text Location

https://doi.org/10.3390/en15238995

e-ISSN

19961073

Issue

23

Volume

15

Grant

1902442

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