Single-phase PV-battery synchronverter with seamless transition to stand-alone mode

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Increasing climate concerns and energy demands have prompted the development of renewable energy systems, mainly wind turbines and photovoltaic (PV) panels. Power electronic converters are used to connect these energy sources to the electrical grid. Increasing the share of these converter-based energy sources in modern electrical power systems, such as the UK, has created some major challenges. Comparatively to conventional synchronous generators, these converters present no inertia or damping. This results in deteriorated dynamic and transient power system performance and a higher risk of instability, and blackouts.The synchronverter or virtual synchronous machine (VSM) concept is already proposed to integrate power electronic-based energy resources into an existing grid so that they are compatible with the existing synchronous generators. Although various techniques have been proposed and presented in different ways, they all aim at providing virtual damping, virtual inertia, and the governor and automatic voltage regulator (AVR) functions. Existing solutions are mainly focused on three-phase converters, while the ever-increasing penetration of single-phase domestic PV systems is calling for similar ideas to be investigated and possible opportunities to be discovered for the single-phase converters. On the other hand, many residential PV systems are dominantly using battery storage, which provides more flexibility as well as complexity for any possible combined solution. The aim of this project is to propose a combination of power electronic topologies and control techniques that will enable domestic single-phase PV-battery systems to mimic the dynamics of synchronous generators and to provide ancillary services during voltage and frequency transients of the utility grid. Additionally, it should be capable of supplying loads in the event of a possible grid disconnection. The performance of the proposed system to different parameters will be fully investigated and a straightforward design and parameter selection algorithm will also be proposed to make the most out of the proposed synchronverter according to different grid code requirements and operator preferences. The theoretical results will be verified through extensive simulations in Matlab/Simulink.