Abstract In a process of fast steam turbine valving employed as a way to avoid loss of synchronism within a power system in the event of a transmission line fault, automatic modification of post fault sustained turbine driving power is initiated in response to operation of generating station line fault responsive protective relay means employed to initiate opening of transmission voltage level circuit breakers, when the fault location and circuit arrangement is such that the opening of one or more back-up circuit breakers resulting from delay in fault clearance would cause the opening of two transmission lines, and provision is made to cancel the modification signal if back-up breaker operation does not take place within a preset time interval.
The method of avoiding development of instability within a power system as a consequence of a transmission line fault which comprises the steps of, a. automatically initiating fast steam turbine valving in response to the occurrence of faults that would cause the opening of two lines if delay in fault clearance caused operation of a delayed fault clearance relay, b. simultaneously automatically initiating turbine governor load signal modification of a nature adapted to reduce sustained post fault turbine driving power. c. cancelling the load signal modification effected in step (b) if normal fault clearance takes place within a predetermined period of time following fault occurrence.
Claim 2
Independent Claim
105 words
The method of avoiding development of instability within a power system as a consequence of a transmission line fault which comprises the steps of, a. automatically initiating fast steam turbine valving in response to the occurrence of faults that would cause the opening of two lines if delay in fault clearance caused operation of a delayed fault clearance relay, b. simultaneously automatically initiating turbine governor load signal modification of a nature adapted to reduce sustained post fault turbine driving power. c. cancelling the load signal modification effected in step (b) if normal fault clearance takes place within a predetermined period of time following fault occurrence.
Claim 3
Dependent Claim
40 words
The method of claim 1 supplemented by prefault manual adjustment of the magnitude of the load modification signal, whereby to take account of the influence of system conditions on the amount of signal needed to avoid loss of system stability.