V-Characteristics Analysis of Non-Salient Pole Synchronous Electrical Machines

Abstract

The optimisation of technical and economic indices of synchronous electrical machines, operating in parallel, is the urgent problem in the exploitation of synchronous machines. The analytical expression of the static stability limit is determined for the operation of nonsalient pole synchronous machine. The equations are offered for the calculation of V-characteristics: one of the equations describes the expression of V-characteristic, situated on the left side of the line cosφ = 1, and the other equation describes the expression of Vcharacteristic, situated on the right side of the line cosφ = 1. There is proved, that the branches of V-characteristics have the shape of hyperbola. The definition for the isogonic lines of V-characteristics is given. Every point of the plane (E, Ia) of V-characteristics is matched by one value of angle φ. The mesh-nomogram of the plane (E, Ia) is presented. The mesh-nomogram enables, according to the given active power of synchronous machine, to define for any value of excitation current the reserve of reactive power, which may be supplied to or may be consumed from the power network. This information enables to use optimally the possibilities of synchronous machine by optimising the circulation of reactive power in electricity transmission lines and networks. The presented graphical materials supplement the lines P = const, corresponding to V-characteristics, by additional lines: Q = const, φ = const as well as by the line of static stability. Ill. 4, bibl. 7 (in English; summaries in Lithuanian, English, Russian).