Synchronization Stability Analysis and Research on Parameters Stability Region in Renewable Energy Grid-Connected Converter System

Renewable energy grid-connected converters (GCCs) employing phase-locked loops (PLLs) have become the prevailing control scheme in wind and photovoltaic power generation systems, owing to their efficiently, controllability, and flexibility. However, the susceptibility to synchronization stability issues arises from weak grid characteristics associated with long-distance transmission lines. To precisely delineate the synchronous stability boundary concerning control and operating parameters in the renewable energy GCC system, the small-signal linearization model of the system is firstly established in this paper. Subsequently, a synchronization stability criterion is derived by considering the static stability conditions of the system and the operating range of the point of common coupling (PCC) voltage. The parameter stability regions for system operating parameters, encompassing active output power and short-circuit ratio (SCR), along with system control parameters, namely PLL proportion and integral coefficient, are provided. The mutual constraints among the system operating parameters and the system control parameters are elucidated from a mechanistic perspective. Validation of the theoretical derivation is achieved through case study examples, finally, highlighting the impact of system operating parameters and control parameters on the stability of the new energy GCC system based on the stability region of parameters. And the application of the stability region of parameters is demonstrated in the planning and operation of grid-connected new energy systems.