Equivalent model for interconnected power systems based on sensitivity consistency of tie-line power

Static security analysis (SSA) is a significant measure to verify the secure and stable operation of power grids. However, it is too time-consuming to perform SSA for interconnected networks due to the scale of network. Therefore, the equivalent-based method attracts attention due to simplifying the external networks (uninteresting networks). However, existing equivalent methods are not suitable for SSA, which are based on the assumption that the topology of internal networks is invariant. This paper proposes a novel static network equivalent method for SSA in interconnected networks. The proposed method can adaptively and precisely preserve the impact of external networks on topology changes of internal networks. Specifically, based on the sensitivity consistency of tie-line power, the equivalent nodal admittance matrix is derived for the external networks. The parameters for the obtained equivalent networks are obtained by least square model with Kirchhoff and necessary logistic constraints to achieve the optimal equivalence accuracy. The accuracy and practicability of proposed method are verified by using IEEE 39-bus system and IEEE 118-bus system.