Stability limits and tuning recommendation of the classical current control providing inertia support

摘要

The drastic increase in renewable energy sources in power grids has raised stability concerns. A particular concern exists in the ability of the converters to preserve frequency stability, due to their inherent lack of inertia provision. Grid forming converters have been presented as a solution to this issue, however the control structure for such converters is significantly different from the vector current control structures utilized by most installed control-converter systems. The classical current controller with a Phase Locked Loop (PLL) can be modified to provide inertia by including an additional control loop that injects active power in the case of a frequency event. This paper presents a detailed stability study, using a small signal model, and presents a set of controller tuning recommendations for the classical current controller with inertia emulation capability. The investigation found that the classical current and PLL tuning decreases the power that can be provided using the inertia emulation loop. Reducing the current loop time constant can allow for stable inertia emulation with classical vector current control.