Fast decoupled steady-state solution for power networks modeled at the bus section level

Conventional tools to provide steady-state power network solutions rely on bus-branch models, in which a ldquobusrdquo is actually the result of merging internal electrical nodes pertaining to given substation. The corresponding network solutions are thus unable to readily provide information about variables internal to the substations, such as power flows through circuit breakers and bus-section nodal voltages. Since the knowledge of such variables is important to several applications, such as real-time topology estimation and corrective switching methods, the need then arises to re-examine the power flow formulation in order to obtain detailed solutions at the substation level. This paper addresses that problem by extending the decoupled power flow formulation in order to allow the representation of selected parts of the network at the substation level. For that purpose, the state vector is expanded so as to include power flows through switching branches as new state variables, in addition to the conventional nodal voltages. Moreover, information regarding the status of switching branches is taken into account as additional linear equations to be solved along with the traditional power flow equations. Simulating results considering several substation layouts and two IEEE test systems are used to illustrate and evaluate the proposed approach.