Improving security and economy of interconnected power network through explicit feasible region of tie-line power transfer

Abstract With the increasing power demand and renewables, the efficient utilization of power resources in each regional network relies on the tie-line power exchanges in interconnected power networks. Consequently, an accurate characterization of the feasible region of tie-line power transfer is crucial for scheduling tie-line power to achieve a secure and efficient utilization of power resources. This paper proposes a characterization method to explicitly capture a feasible region of tie-line power transfer considering steady-state constraints with reactive power and voltage limits and transient constraints. The steady-state and transient constraints are explicitly derived: 1) a power transfer distribution factor matrix with reactive power and voltage magnitude is derived to equivalently reflect the steady-state operational region with fewer variables and constraints; 2) the transient constraints of the tie-line power are derived based on the swing and current injection equations and a constraint transcription technology is adopted to convert transient constraints from continuous-time domain to a vector space, which makes it possible to identify the feasible region of tie-line power transfer. The steady-state and transient constraints are explicitly projected to the tie-line power space via a vertex search method. Finally, this paper utilizes the feasible region of tie-line power transfer to perform the tie-line scheduling via the proposed linear programming model. The proposed tie-line scheduling model can promote the optimal utilization of generation dispatches, which guarantees security and improve economics in the interconnected power network. The numerical results based on the IEEE 9-bus and IEEE 118-bus test systems verify the effectiveness of the proposed methods.