Quality norms for short-time variation of supply voltages and frequencies, the variation influences over stability of electroenergetical systems with localised power

The paper presents theoretically and experimentally deduced quality norms for short-time variations of supply voltages and frequencies on localised power networks. It is theoretically demonstrated that for the most important consumer in a ship power system, the voltage variation mode is within the range of ±15% in two cases: (a) with an exciter-control system; and (b) without an exciter-control system. By experiment, the same conclusions are obtained. Examples for short-time supply voltage variation modalities when important consumers are connected and disconnected, at various voltage levels (400 V, 660 V), are shown. The modelling of a 210 kVA, 230 V generator auto-synchronization, by a 560 kVA transformer within the naval network, supplied by three identical generators, is presented. The influences of supply voltage variations over normal operation transient processes and the mechanical characteristics of induction motors in the network are discussed All these conclusions are obtained by experiments