Active and reactive power regulation in nano grid-connected hybrid PV systems

The electrical systems are moving very rapidly to small/medium size distributed generation and storage system with the main goal to improve the level of energy self-sufficiency, with a drastic change of the user model from passive to active (prosumers). The prosumers will group themselves at the level of nano and micro smart grids. In this context models of hybrid systems with photovoltaic (PV) system, battery energy storage system (BEES) and/or diesel generator are needed. Since power quality represents an important issue for smarts grid that can work also in off-grid configuration, the aim of the control logic is the achievement of voltage and frequency regulation. For this purpose, different reference standards are considered. In the proposed case study, two different operation modes are investigated: grid-connected mode and stand-alone mode, depending on the different role of diesel generator and external power grid. Two different control logics for the system PV+BEES are adopted for the two operation modes under study. Accordingly, two different simulations with a 24-h horizon are run and the results are discussed, in terms of active and reactive power of the hybrid system components, voltage and frequency profile at the connection bus. Also a transient analysis on the diesel generator connection and disconnection is conducted.