Voltage stability constrained dynamic optimal reactive power flow based on branch-bound and primal–dual interior point method

• A mapping-based partitioning algorithm for reactive voltage control is proposed.
• Effective dynamic reactive power reserves of reactive power sources are calculated.
• Dynamic reactive power reserves are taken as objective functions and constraints.
• Voltage collapse can be mitigated by the proposed model in this paper.
• Branch-bound and primal–dual interior point method is proposed to solve the problem.

A day-ahead voltage stability constrained dynamic optimal reactive power flow (VSC-DORPF) model is proposed in this paper. The amount of dynamic reactive power reserves (DRPR) is used as a measure of voltage stability of power system. The effective dynamic reactive power reserves (EDRPR) of reactive power sources are calculated to obtain DRPR of each area and the maximum variations in reactive power generation under contingency are taken as the required minimal DRPR for each area. Then the DRPR are introduced into the VSC-DORPF model as one of multiple objective functions and constraints in order to enhance the voltage stability of power system. A hybrid method, integrated by branch-bound method and primal–dual interior point (PDIP) method, is proposed to solve this VSC-DORPF problem. The discrete control variables and the time coupled constraints are handled by the proposed branching and pruning principles. As a result, the VSC-DORPF problem is decomposed into a series of optimal reactive power flow (ORPF) problems with continuous control variables only. Numerical tests with IEEE 30-bus system and IEEE 118-bus system show that the proposed model and method are effective.