## Abstract

This paper proposes a new Secondary Frequency Consensus (SFC) control scheme for inverter-based AC microgrids relying on Negative Imaginary (NI) systems theory. A microgrid consists of many Distributed Generating (DG) units whose dynamics can be modelled by a set of nonlinear differential-algebraic equations. Each DG can be feedback linearised into a single integrator system, which resembles the simplified frequency dynamics of a microgrid. A network of

many such feedback-linearised DG units gives rise to a homogeneous NI multi-agent system (MAS). Interestingly, a single integrator MAS, owing to be NI, can be conveniently stabilised by a distributed Strictly NI (SNI) controller depending only

on the definiteness of the DC gain matrix of the controller. It also successfully achieves the consensus, resulting in frequency synchronisation among all DG units and the main grid. An in-depth Matlab simulation case study was carried out to test the usefulness and performance of the proposed scheme.

many such feedback-linearised DG units gives rise to a homogeneous NI multi-agent system (MAS). Interestingly, a single integrator MAS, owing to be NI, can be conveniently stabilised by a distributed Strictly NI (SNI) controller depending only

on the definiteness of the DC gain matrix of the controller. It also successfully achieves the consensus, resulting in frequency synchronisation among all DG units and the main grid. An in-depth Matlab simulation case study was carried out to test the usefulness and performance of the proposed scheme.

Original language | English |
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Title of host publication | Proceedings of the 62nd IEEE Conference on Decision and Control, Marina Bay Sands, Singapore, Dec 2023 |

Publication status | Accepted/In press - 15 Sept 2023 |