Analysis of transient field problems in electrical machines allowing for end leakage and external reactances

Recently, the analysis of the transient field problems in the cross section of a microalternator during a field decrement test was described. Here, a simplified formulation of the transient field problems is achieved with the introduction of the currents in the closed windings as additional state variables to the field problem. The new formulation avoids the difficulties that arise with adopting expressions for the winding resistances as functions of time. Also, it provides separate equations for the connected terminal networks which overcomes the difficulties that arise with the use of the conductivity matrices in a generalized connected terminal network. The method is applied to a 333-MVA turboalternator to simulate the field and stator decrement tests. Also, the effects of adding external reactances to the field and stator circuits on the machine performance are obtained.