PV-Battery Assisted Three-Level T-Type Inverter for AC Residential Nanogrid Realized With Small-Scale HIL Units

Abstract

Hardware-in-the-loop (HIL) testing methods by means of HIL units or real-time simulators (RTS), are becoming broadly accepted for validating of control systems in many technical areas. This new approach brings advantages such as the acceleration of the industrial and the research development cycle and offers a risk-free and flexible environment for the testing and the evaluation stages before the control deployment in the physical system. Nevertheless, the realization of such methodology can be very challenging in some large or complex plants. In this scenario, a proper simulation of the physical system, that is, the development of its accurate digital twin, demands a suitable and reliable sectioning of the different components into different parts running in parallel into different HIL units. This is the case of a nanogrid (nG) involving some prosumers with renewable energy resources (RES), and their corresponding multiple power electronic converters. These power electronic converters operate at high switching frequencies, which require a very low simulation time step, as well as a high number of input and output signals in closed-loop operation. This work analyzes in detail how to realize a digital twin of a two-prosumer residential nG including a photovoltaic (PV)-battery assisted three-level T-type (3L T-Type) inverter and managed by a hierarchical grid-forming (GFM) control structure by means of RTS based on the RT Box 1 by Plexim. The analysis allows to test the proposed GFM controls and the control hardware in steady and transient conditions, validating their accurate performance.