Influence of Equivalent Impedance of Connecting Network on Stability Analysis For Renewable Energy Power Plant

Centralized penetration of large scale renewable energy brings great challenges to the safe and stable operation of modern power system. Exact equivalent model of renewable energy power plant (REPP) is the basis for analyzing the penetration stability, and connecting network equivalence is an important item in REPP dynamic equivalence process. In this paper, two equivalence rules for connecting network are introduced, namely consistent power loss rule (CPLR) and consistent impedance rule (CIR) originated from impedance analysis method for sub/super oscillation research. Then influence of equivalent impedance value of connecting network is discussed on stability analyses under large and small disturbances. Finally, the applicability of two equivalence rules to stability analyses are compared. Results show that for small disturbance stability analysis and phase locked loop (PLL) related transient synchronization instability, CPLR based simplified equivalent model may cause biased results or wrong conclusions, while CIR displays a better applicability.