Protective relay system and sampling synchronizing method therefor
First Claim
1. A sampling synchronizing method for use in a protective relay system for an electric power system having two or more terminals at which electrical quantity is sampled, two of the terminals being coupled to form a pair, said sampling at each terminal being made in synchronism with a clock signal produced at each terminal, and electrical quantity data obtained by the sampling at each terminal of said pair is transmitted to the opposite terminal of said pair to be used for protection at said opposite terminal, the clock signals at the terminals of said pair having the same frequency.whereinsynchronous signals F0, F1, are transmitted from each terminal of said pair toward the opposite terminal;
- time data T1 is transmitted from one terminal SS2 of said pair toward the other terminal SS1 of said pair, in association with the synchronous signal, the time data T1 indicating a time point T1 of the transmission of the synchronous signal F1 toward said other terminal with reference to occurrence of the clock signal at said one terminal;
time data T0 is transmitted from said other terminal toward said one terminal, in association with the synchronous signal F0 in an M0 -th clock period (M0 being a predetermined natural number) after the reception of the synchronous signal F1 associated with the time data T1 from said one terminal, the time data T0 indicating a value given by;
space="preserve" listing-type="equation">t.sub.0 -T1+t.sub.2where t0 represents a time point of the reception of the synchronous signal F1 associated with the time data T1 from said one terminal SS2 with reference to occurrence of the clock signal at said other terminal SS1,T1 represents a value indicated by the time data T1, andt2 represents a time point of said transmission of the synchronous signal F0 associated with the time data T0 toward said one terminal SS2 with reference to occurrence of the clock signal at said other terminal SS1, anda time deviation Δ
T in the occurrence of the clock signal between said pair of terminals is determined at said one terminal in accordance with the time data T0 and a time point t3 of the reception of the synchronous signal F0 associated with the time data T0 from said other terminal with reference to occurrence of the clock signal; and
the timing of the occurrence of the clock signal at said one terminal is adjusted in accordance with the time deviation Δ
T.
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Accused Products
Abstract
In a protective relay system for an electric power system having two terminals at which electrical quantity is sampled in synchronism with a clock signal produced at each terminal, and the sampled electrical quantity data are exchanged for protection at said opposite terminal: a synchronous signal is transmitted from each terminal toward the opposite terminal; time data T1 is transmitted from a first terminal SS2 toward a second terminal SS1, the time data T1 indicating a time point t1 of the transmission of the synchronous signal toward the second terminal SS1 with reference to the clock signal; the time data T0 is transmitted from the second terminal SS1 toward the first terminal SS2, subsequent to reception of the synchronous signal from the first terminal SS2, the time data T0 indicating a value
t.sub.0 -T1+t.sub.2
where t0 represents a time point of the reception of the synchronous signal with reference to the clock signal at the second terminal SS1, T1 represents the value as indicated by the time data T1, and t2 represents a time point of the transmission of the synchronous signal with reference to the clock signal; a time deviation ΔT in the occurrence of the clock signal between the two terminals is determined from the time data T0 and a time point t3 of the reception of the synchronous signal with reference to the clock signal; and the timing of the occurrence of the clock signal at said one terminal is adjusted in accordance with ΔT.
28 Citations
13 Claims
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1. A sampling synchronizing method for use in a protective relay system for an electric power system having two or more terminals at which electrical quantity is sampled, two of the terminals being coupled to form a pair, said sampling at each terminal being made in synchronism with a clock signal produced at each terminal, and electrical quantity data obtained by the sampling at each terminal of said pair is transmitted to the opposite terminal of said pair to be used for protection at said opposite terminal, the clock signals at the terminals of said pair having the same frequency.
wherein synchronous signals F0, F1, are transmitted from each terminal of said pair toward the opposite terminal; -
time data T1 is transmitted from one terminal SS2 of said pair toward the other terminal SS1 of said pair, in association with the synchronous signal, the time data T1 indicating a time point T1 of the transmission of the synchronous signal F1 toward said other terminal with reference to occurrence of the clock signal at said one terminal; time data T0 is transmitted from said other terminal toward said one terminal, in association with the synchronous signal F0 in an M0 -th clock period (M0 being a predetermined natural number) after the reception of the synchronous signal F1 associated with the time data T1 from said one terminal, the time data T0 indicating a value given by;
space="preserve" listing-type="equation">t.sub.0 -T1+t.sub.2where t0 represents a time point of the reception of the synchronous signal F1 associated with the time data T1 from said one terminal SS2 with reference to occurrence of the clock signal at said other terminal SS1, T1 represents a value indicated by the time data T1, and t2 represents a time point of said transmission of the synchronous signal F0 associated with the time data T0 toward said one terminal SS2 with reference to occurrence of the clock signal at said other terminal SS1, and a time deviation Δ
T in the occurrence of the clock signal between said pair of terminals is determined at said one terminal in accordance with the time data T0 and a time point t3 of the reception of the synchronous signal F0 associated with the time data T0 from said other terminal with reference to occurrence of the clock signal; andthe timing of the occurrence of the clock signal at said one terminal is adjusted in accordance with the time deviation Δ
T. - View Dependent Claims (2, 3, 4, 5, 6)
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- 7. A protective relay system in an electric power system having two or more terminals, two of the terminals being coupled to form a pair, and relay devices each provided at each of the terminals of said pair for sampling electrical quantity in synchronism with a clock signal produced at each of the terminals of said pair and producing electrical quantity data indicating the sampled electrical quantity, and data exchange devices each provided at each of the terminals of said pair transmitting the electrical quantity data toward the opposite terminal of said pair and receiving the electrical quantity data transmitted from the opposite terminal of said pair, said relay device at each terminal of said pair being responsive to the electrical quantity data transmitted from the opposite terminal protecting the electric power system, the clock signals at the terminals of said pair having the same frequency,
said data exchange device at each terminal comprising a clock signal generating circuit periodically generating said clock signal, and a transmitting circuit transmitting synchronous signals F0, F1 toward the opposite terminal, the data exchange device 9 of one terminal SS2 of said pair comprises a time data forming means 24 producing time data T1 indicating the time point t1 of the transmission of the synchronous signal F1 toward the other terminal SS1 with reference to occurrence of the clock signal at said one terminal SS2, the transmitting circuit 21 of said one terminal SS2 transmits the time data T1 in association with the synchronous signal F1, the transmitting circuit 11 of said other terminal SS1 transmits the synchronous signal F0 in an M0 -th clock period (M0 being a predetermined natural number) after the reception of the synchronous signal F1 associated with the time data T1 from said one terminal, the data exchange device 5 of said other terminal SS1 further comprises a time data forming means 14 for producing time data T0 indicating a value given by - space="preserve" listing-type="equation">t.sub.0 -T1+t.sub.2
where t0 represents a time point of the reception of the synchronous signal F1 associated with the time data T1 from said one terminal SS2 with reference to occurrence of the clock signal at said other terminal SS1, T1 represents a value indicated by the time data T1, and t2 represents a time point of said transmission of the synchronous signal F0 toward said one terminal SS2 with reference to occurrence of the clock signal at said other terminal SS1, the transmitting circuit 11 of said other terminal SS1 also transmits the time data T0 in association with said synchronous signal F0, the data exchange device 9 of said one terminal SS2 further comprises a time deviation detecting means 25 for determining time deviation Δ
T in the occurrence of the clock signal between said pair of terminals, in accordance with the time data T0, and the time point t3 of reception of the clock signal F0 associated with the time data T0 from said other terminal SS1 with reference to occurrence of the clock signal at said one terminal SS2, andthe clock signal generating circuit 23 of said one terminal SS2 is responsive to the time deviation Δ
T for so adjusting the timing of the occurrence of the clock signal as to make the deviation closer to zero.- View Dependent Claims (8, 9, 10, 11, 12, 13)
Specification
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- Resources
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Current AssigneeKabushiki Kaisha Toshiba (Toshiba Corporation)
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Original AssigneeKabushiki Kaisha Toshiba (Toshiba Corporation)
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InventorsYamaura, Mitsuru, Shuto, Ituo
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Primary Examiner(s)Pellinen, A. D.
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Assistant Examiner(s)Wysocki, A. Jonathan
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Application NumberUS06/639,357Time in Patent Office767 DaysField of Search361/64, 361/65, 361/66, 361/68, 361/69, 361/79, 361/81, 361/83, 340/825.2, 340/870.13, 455/51, 455/80, 455/73, 455/212, 455/213, 375/107, 375/108, 375/109, 375/111US Class Current361/68CPC Class CodesH02H 3/30 using pilot wires or other ...H02J 13/00012 using an auxiliary transmis...H02J 13/0004 involved in a protection sy...
