The neutral-point piloted inverter topology applied to grid emulation

Grid emulation with power-electronic converters is an emerging concept for testing and validating renewable energy systems in a laboratory environment. Such emulation systems require power converters with high power ratings up to several tens of megawatts, addressed with medium-voltage converters providing comparatively low switching frequencies. This characteristic influences the system design for harmonics, passive filters, and dynamic operation. The three-level neutral-point piloted inverter has topological aspects that support increased switching frequency. This paper describes the benefits of using this topology for grid emulation, with a focus on modulation of parallel inverters, dynamics, and harmonic injection for high orders.