초록 ▼

As a improved way of effecting fast valving of turbines of power system steam-electric generating units for the purpose of improving the stability of power transmission over transmission circuits to which their generators make connection, when stability is threatened by line faults and certain other

As a improved way of effecting fast valving of turbines of power system steam-electric generating units for the purpose of improving the stability of power transmission over transmission circuits to which their generators make connection, when stability is threatened by line faults and certain other stability endangering events, the heretofore employed and/or advocated practice of automatically closing intercept valves at fastest available closing speed in response to a fast valving signal, and thereafter automatically fully reopening them in a matter of seconds, is modified by providing to reopen the valves only partially to and thereafter retain them at a preset partially open position. For best results the process of what can be termed sustained partial reopening is so effected as to result in its completion within a fraction of a second following the peak of the first forward swing of the generator rotor. Control valves may be either held open, or automatically fully or partly closed and thereafter fully opened in a preprogrammed manner, or automatically moved to and thereafter held in a partly closed position, by means of a preprogrammed process of repositioning in which the valves may optionally be first fully or partly closed and thereafter partly reopened. Avoidance of discharge of steam through high pressure safety valves can be had with use of suitably controlled power operated valves that discharge steam to the condenser or to atmosphere. Where there is an intermediate pressure turbine that is supplied with superheated steam, use of sustained partial control valve closure, if employed, is supplemented by provision for reduction of rate of heat release within the steam generator in order to protect the reheater from overheating. As a way to restrict increase of reheat pressure of fossil fuel installations, and to minimize increase in the MSR (moisture separator-reheater) pressure of nuclear units, provision is optionally made of normally closed by-pass valves which are arranged to accept reheat or MSR pressure steam and discharge to the condenser in response to either an an increase of reheat or MSR pressure that takes place other than slowly, or to a fast valving signal, or both.

대표청구항 ▼

In a power system which includes a plurality of prime mover driven generators, which are interconnected by a plurality of alternating current transmission circuits, and which include at least one generator that is driven by a compound type steam turbine incorporating control valves ahead of the high

In a power system which includes a plurality of prime mover driven generators, which are interconnected by a plurality of alternating current transmission circuits, and which include at least one generator that is driven by a compound type steam turbine incorporating control valves ahead of the high pressure turbine, and intercept valves ahead of the turbine or turbines that are driven by steam that is discharged by the high pressure turbine, the method of fast valving of the said compound turbine, as a way to avoid development of system instability, which comprises the steps of 1. providing within the turbine\s control system for a predetermined response to a fast valving signal input which response will bring into effect preprogrammed processes of, a. at least partial closure of the turbine\s intercept valves, effected fast enough to have a favorable effect on generator rotor first swing stability, b. sustained type partial intercept valve reopening. 2. providing in a preprogrammed manner so that, a. a fast valving signal is generated on the occurrence of certain types of system stability endangering events [of a type]that cause the said generator to experience a sudden at least momentary reduction of load, b. the said fast valving signal is made available as an input to that portion of the turbine\s control system that is adapted to bring into effect the said predetermined response.