Power plant system and control therefor

Claim 1

IN A POWER PLANT SYSTEM WHEREIN A NUMBER OF SEPARATE ELECTRICAL GENERATING PLANTS ARE INTERCONNECTED FOR POWER INTERCHANGE BY TIE-LINES WITH THE POWER INTERCHANGE BEING SCHEDULED AND WITH EACH PLANT INCLUDING A TURBO-GENERATOR AND A STEAM GENERATOR SUPPLYING THE MOTIVE POWER THEREFOR AND WITH EACH STEAM GENERATOR HAVING TUBULAR HEAT EXCHANGE SURFACE INCLUDING A SUPERHEATER PORTION AND BEING REQUIRED TO TAKE CARE OF LOAD CHANGES IN ITS OWN PREDETERMINED AREA, THE SYSTEM OF CONTROLLING EACH PLANT COMPRISING MEANS PROVIDING A SIGNAL THAT IS A FUNCTION OF THE VARIATION OF THE ACTUAL INTERCHANGE FROM THE REQUIRED INTERCHANNGE, MEANS PROVIDING A SIGNAL THAT IS A FUNCTIION OF THE VARIATION OF THE FREQUENCY OF THE POWER PLANT SYSTEM FROM A PREDETERMINED DESIRED FREQUENCY, MEANS COMBINING THESE SIGNALS IN A MANNER THAT THEY EFFECTIVELY CANCEL EACH OTHER IF THE CHANGES WERE PRODUCED BY A LOAD CHANGE OUTSIDE THE AREA OF THE PARTICULAR PLANT BUT ARE ADDED IF THE CHANGES WERE PRODUCED BY A LOAD CHANGE WITHIN THE AREA OF THE PARTICULAR PLANT OR BY A CHANGE IN SCHEDULED INTERCHANGE, MEANS PROVIDING A SIGNAL THAT IS A FUNCTION OF THE OUTPUT OF THE PLANT TO ITS PREDETERMINED AREA, SAID COMBINING MEANS COMBINING THIS SIGNAL WITH THE OTHER TWO SO THAT A SIGNAL THAT IS A FUNCTION OF THE DEMAND LOAD ON THE PARTICULAR PLANT IS PRODUCED, MEANS PROVIDING A SIGNAL THAT IS A FUNCTION OF THE INLET AND OUTLET STEAM TEMPERATURES OF A PREDETERMINED PORTION OF THE SUPERHEATER, COMPUTER MEANS RECEIVING THE AFOREMENTIONED SIGNALS AS INPUT INTELLIGENCE AND EFFECTIVE TO CONTINUOUSLY PROVIDE AN OUTPUT SIGNAL THAT IS A FUNCTION OF THE DIFFERENCE BETWEEN THE REQUIRED INLET STEAM TEMPERATURE FOR THE DEMAND LOAD AND TO GIVE A PREDETERMINED OUTLET STEAM TEMPERATURE AND THE ACTUAL INLET STEAM TEMPERATURE, MEANS RESPONSIVE TO THIS OUTPUT SIGNAL EFFECTIVE TO REGULATE THE INLET STEAM TEMPERATURE AND INDEPENDENT FROM THE FIRING RATE OF THE STEAM GENERATOR WITH THIS REGULATION BEING