Apparatus to generate minimally delayed instructions for turbine valves in the event of power system short circuits
AssigneeBBC Brown, Boveri & Company, Limited
InventorsHeinz Bloch, Ernst Wirth
Life of this patent
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Abstract
Apparatus for generating minimally delayed closing instructions for turbine valves of turbo-generator sets in the event of power system short circuits wherein major faults resulting in a drop in the system voltage are detected and act upon the valve means controlling the fluid flow to the turbine in such manner that a rapid closure of the valve means prevents the turbo-generator from falling out of step in the case of a sustained fault condition. A provisional valve-closing signal is produced upon a predetermined drop in the system voltage but this is cancelled in the event that the ensuing acceleration of the turbo-generator set does not increase to a predetermined level within two revolutions of the set.
Claims5
The combination with a turbo-set comprising a turbine shaft coupled to an alternating current electrical generator whose output is delivered to a high-voltage power system and wherein valve means are provided for controlling the fluid flow to said turbine of an improved arrangement for effecting a rapid closure of said valve means with minimally delayed closing instructions in the event of a sustained major fault on said power system which comprises;
- means producing a first provisional signal upon a predetermined drop in the network voltage and which is passed to said valve means for commencing a closing operation of said valve means,
- means producing a second signal having a level indicative of the acceleration of the turbine shaft within two revolutions thereof following the drop in network voltage, and
- means responsive upon a failure of said second signal to reach a predetermined level for cancelling out said first signal thereby terminating the closing operation of said valve means.
The combination with a turbo-set comprising a turbine shaft coupled to an alternating current electrical generator whose output is delivered to a high-voltage power system and wherein valve means are provided for controlling the fluid flow to said turbine of an improved arrangement for effecting a rapid closure of said valve means with minimally delayed closing instructions in the event of a sustained major fault on said power system which comprises:
- means for measuring the network voltage,
- means comparing said measured network voltage with a reference limit voltage and which produces a first provisional valve closing signal when said measured network voltage falls below said reference limit voltage by a predetermined amount,
- a memory to the set input of which said first provisional valve-closing signal is fed,
- means for measuring the acceleration of said turbine shaft within two revolutions thereof,
- means comparing said measured turbine shaft acceleration with a reference limit value of acceleration and which produces a second signal when said measured turbine shaft acceleration exceeds said reference acceleration,
- means for actuating said valve means to a closed position and which are connected to the output signal from said memory,
- an AND gate having direct and inverting inputs,
- means connecting the output signal from said memory through a delay unit to the direct input of said AND gate,
- means connecting said second signal to the inverting input of said AND gate, and
- means connecting the output from said AND gate to the reset input of said memory.
Dependencies are inferred from the claim text.