GB337575A - Improvements in electric power station systems having automatic voltage regulation - Google Patents

Abstract

337,575. Allmõnna Svenska Elektriska Aktiebolaget. Oct. 15, 1928, [Convention date]. Regulation, automatic; running generators in parallel; systems depending on static transformers.-To avoid the over and under excitation of parallel-connected alternators with automatic regulators, a compounding impedance 13, 23, is placed in the circuit of the controlling coil of each regulator 11, 21 carrying a current corresponding to that of the appropriate generator and compounding in a negative sense for the equalizing current from an over-excited machine, another compounding impedance 14, 24 being included in each controlling coil circuit, acting in a positive sense and in respect of the total load current of the paralleled machines. Where machines are paralleled through transformers, Fig. 2, the impedances 17, 27 may compound only in respect of a portion of the voltage drop in the transformer windings. Where the load of two or more feeders is in question, the currents in the impedances 14, 24 are proportional to the arithmatic value of all feeder currents, the current transformers of all being in series. In high tension systems intermediate transformers 55, 65, Fig. 2, are used shunted by resistances or with opposed tertiary windings to avoid high saturation due to differences in line current.