Optimal Power Flow With Transient Stability Constraints Based On Sensitivity Of Transient Energy Margin

With the capacity of modern power systems increasing continuously, the scale ofpower network is larger and larger, which is developing along a regional andinternational direction. Therefore, an extensive concern is paid close attention tostability and security about power systems. Furthermore, in order to reduce the cost ofelectric energy and improve economic benefits, modern union power systemssometimes operate on the edge of transient stability constraints. Disasters of larger scaleelectric power cut have been caused by destruction of transient stability. For this reason,it is essential to take account of transient stability constraints in power systemsoperation.A algorithm for optimal power flow with transient stability constraints (OPFTSC)based on transient energy margin is presented in the paper. It regards calculation resultsof solving optimal power flow as initial value of solving OPFTSC. In a current state,transient stability analysis of power systems is executed making use of time domainsimulation. At first, those contingencies, which are able to remain transient stability, arefiltered out. Transient energy margin of severe contingencies are calculated throughhybrid method. According to difference of their value, these severe contingencies aresorted aiming at finding out the severest contingency. According to a approximatelinear relation between transient energy margin of the severest contingency andvariations of active power and sensitivities of transient energy margin of the severestcontingency for active power of generators in power system, active power of allgenerators are able to be adjusted effectively. As a result, Power system is able to beeconomic and satisfies transient stability at the same time. The efficiency of thealgorithm is improved by the application of variable line search strategy in calculationprogram. The global convergence is ensured for optimal power flow with transientstability constraints considering multiple contingencies.Taking several IEEE bus systems for examples, the validity of the method isproved.