Analysis of Power System Stability Under Slowly Varying Perturbations in Renewable Generation

Although the impact of persistent perturbation from renewable energy on power system stability has been studied, the effects of slowly varying disturbances remain unexplored. This paper proposes a new stability concept, locally differential input-to-state stability (LDISS), based on the input-to-state stability framework. The new concept enables the characterization of system stability under slowly varying fluctuations in renewable energy output. A Lyapunov-like analysis method provides a stability condition for LDISS. The analytical approach is applied in a single-machine infinite-bus system with additive perturbation to analyze its stability. Experimental results on the same system verifies the theoretical method.