Grid-friendly Matching Control of Synchronous Machines by DC/AC Converters in Bulk Power Networks

Abstract

An islanded inverter-based microgrid is a collection of heterogeneous DC energy resources, e.g., photovoltaic arrays, fuel cells, and energy-storage devices, interfaced to an AC distribution network and operated independently from the bulk power system. Energy conversion is typically managed by power electronics in voltage source inverters. Drawing from the control of synchronous machines in bulk power systems, different control schemes have been recently adopted in order to achieve a stable network operation. The vast majority of academic and industrial efforts opt for these strategies during real-time operation. Starting with a dynamical averaged DC/AC converter model, we review different controllers by presenting their main scope analytically and through simulations. Next, we explore a new alternative of controlling DC/AC converters in bulk power systems by matching traditional synchronous machines with emphasis on the role that DC-circuit can play in control architecture, usually neglected in conventional strategies. Compared to standard emulation methods, our controller relies solely on readily available DC-side measurements and takes into account the natural DC and AC storage elements. As a result, our controller is generally faster and less vulnerable to delays and measurement inaccuracies. We additionally provide insightful interpretations of the suggested control, various plug-and-play properties of the closed-loop, such as steady-state power flow analysis, passivity with respect to the DC and AC ports, stability proof as well as high-level control architectures contributing to enhancing the controller performance and attaining further control goals, which we illustrate in both analysis and simulation.