Robust transmission capacity margin evaluation based on All-Scenario-Feasible optimization

A robust and effective evaluation method for the safety of optimal generation scheduling has great potential on optimizing operation of electrical power and energy system. Based on the concept of transmission capacity margin, a robust model of transmission capacity margin evaluation (TCME) is established to assess the overload risk of transmission lines when loads fluctuate. This TCME method can provide the system operators with useful information such as possibly overloaded lines and time periods when lines are potentially overloaded under the uncertainties of nodal loads. However, TCME formulation has a multi-level (min-max) structure and the solution methods are usually complicated. In order to overcome the computational complexity of original problem, an All-Scenario-Feasible optimization is utilized. It is established based on very limited scenarios while the solution is feasible to all scenarios. The proposed formulation is single-level rather than multi-level. So no iterative algorithms are needed and commercial solver like CPLEX could be directly adopted. In order to use the proposed formulation for large-scale power grid, considering that the transmission capacity constraint is the most important one in all problem constraints, we further reduce the number of scenarios. Numerical testing is also performed and the results show that the proposed formulation is effective.