Stability enhancement module for grid‐following converters: Hardware implementation and validation

Abstract

Summary Low‐frequency oscillations limit power delivery of voltage‐source converter interfaced resources, for example, wind and solar, operating in grid‐following control mode. Our prior research identified the instability mechanism as the coupling between real power and voltage at point of common coupling. In turn, a stability enhancement control was proposed to weaken the coupling by introducing a simple voltage‐based feedback loop. The stability enhancement control has been validated via electromagnetic transient simulation testbeds. The objectives of this paper are (a) to provide a more insightful explanation of the enhancement module by examining the impedance of the grid‐following converter and (b) to verify the performance of the stability module using a hardware testbed. The theoretic examination demonstrates that stability enhancement module effectively reduces the negative resistance effect of Zqq and thus boosts stability. The experimental research leads to a hardware testbed of a grid‐following converter with the ability of demonstrating low‐frequency oscillations. The experimental results demonstrate the efficacy of the proposed stability enhancement control and the readiness of commercial realization of the stability enhancement unit.