ELECTRIC ACCIDENT DETECTING/PROTECTING METHOD

• Main Authors: MIZUKAMI SATORU, NANBA SHIGEAKI, UDA KENGO
• Format: Patent
• Language: English
• Published: 21.12.2006
• Subjects: CONTROL OR REGULATION OF ELECTRIC MOTORS, ELECTRIC GENERATORSOR DYNAMO-ELECTRIC CONVERTERS; CONTROLLING TRANSFORMERS, REACTORS OR CHOKE COILS; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER; ELECTRICITY; EMERGENCY PROTECTIVE CIRCUIT ARRANGEMENTS; GENERATION

PROBLEM TO BE SOLVED: To provide an electric accident detecting/protecting method at occurrence of an accident in an operating range of a low-frequency region which is not covered even by a frequency region out of a rating already operated. SOLUTION: In an electric system comprising a thyristor starting device 1, a generator 2 and an exciting transformer 3, when the electric accident occurs at a secondary side of the exciting transformer at an hour of t1 of time t0 of a speed increase of the generator (the low-frequency region)(both of a circuit breaker 4 and a disconnector 5 are open), a current (i) flowing into the exciting transformer rapidly increases from an almost zero value, and a current set value I1 increases to be I2+(i), while the current I2 supplied to the generator reduces, leading to fall in voltage of the generator and a decrease in the number of revolutions of the generator by which such a phenomenon occurs as a speed increase rate (U) of the generator deviates toward a point 11 from a point 10. When the speed increase rate (U) of the generator exceeds a dispersion tolerance of a control set index value of the thyristor starting device 1, an accident is judged to be the electric accident. COPYRIGHT: (C)2007,JPO&INPIT