System for providing protection for a high voltage transmission line

Claim 1

A system comprised of a phase selector relay and a distance measuring relay both for protecting one or more phases of one or more zones of a high voltage A.C. transmission line, said phase selector relay developing a first operating signal V OP1 and a first polarizing signal V POL1 for each phase of the transmission line and each representative of the current and voltage conditions existing in each of the phases, said distance measuring relay developing a second operating signal V OP2 and a second polarizing signal V POL2 for each phase of the transmission line and each representative of the current and voltage conditions existing in each of the phases, said protective system further having a first and a second phase angle comparator comprising respectively interconnected first and second AND circuit means and first and second TIMER means, said first AND circuit means being responsive to the phase coincidence between said first operating signal (V OP1 ) and said first polarizing signal (V POL1 ) for developing a first output signal which is routed to and activates said first TIMER means, said first TIMER means generating a first control signal upon the expiration of a first predetermined time duration, said second AND circuit means being responsive to said first control signal and to the phase coincidence between said second operation signal (V OP2 ) and said second polarizing (V POL2 ) signal for developing a second output signal which is routed to and activates the second TIMER means, said second TIMER means generating a second control signal upon the expiration of a second predetermined time duration, each of said first and second control signals being adapted to control circuit breaking means for causing said one or more phases of the one or more zones of the transmission line to be decoupled from the remainder of the transmission line, said protective system further comprising means for developing said V OP1 , V POL1 , V OP2 and V POL2 signals respectively representative of the following relationships: V.sub.OP1 =K.sub.4 {(1+K.sub.5)[(I.sub.P -I.sub.O)Z.sub.R1 +K.sub.O I.sub.O Z.sub.RO -V.sub.PN ]+K.sub.3 V.sub.P1M } (a) where the subscript P shown for the current (I) and voltage (V) quantities is either A, B, or C to indicate the particular phase of the transmission line related to the particular phase of the V OP1 signal; K 3 , K 4 , and K 5 are phase selector relay constants; K O is a zero-sequence line impedance compensation factor substantially equal to the amplitude of the quantity Z LO /Z L1 , where Z LO is equal to the zero-sequence line impedance and Z L1 is equal to the positive-sequence line impedance; I O is the zero-sequence current flowing within the three (3) phase transmission line; Z R1 is the replica positive sequence impedance of the transmission line; Z RO is the replica positive sequence impedance of the transmission line, but with the phase angle of the zero-sequence impedance of the transmission line; I P is representative of the current flowing in the transmission line related to the particular phase of the V OP1 signal; V P1M is the positive sequence component of a prefaulted transmission line voltage related to the particular phase of the V OP1 signal, and; V PN is the phase-to-neutral voltage of the transmission line related to the particular phase of the V OP1 signal; V.sub.POL1 =K.sub.2 V.sub.P1M (b) where K 2 is a phase selector relay constant, and; V P1M is the positive sequence component of the prefaulted transmission line voltage related to the particular phase of the V POL1 signal; V.sub.OP2 =K.sub.8 [(I.sub.P -I.sub.O)Z.sub.R1 +K.sub.O I.sub.O Z.sub.RO -V.sub.PN ] (c) where K 8 is a distance measuring relay constant; K O , I P , I O , V PN , Z R1 and Z RO are as described for expression (a); V.sub.POL2 =K.sub.6 I.sub.P2 X.sub.R -K.sub.7 V.sub.P2 (d) where K 6 and K 7 are distance measuring relay constants; X R is the replica negative sequence reactance of the transmission line; I P2 is the negative sequence component of the current flowing in the transmission line related to the particular phase of the V POL2 signal, and; V P2 is the negative sequence component of the voltage existing in the transmission line related to the particular phase of the V POL2 signal.

Claim 2

A system comprised of a phase selector relay and a distance measuring relay both for protecting one or more phases of one or more zones of a high voltage A.C. transmission line, said phase selector relay developing a first operating signal V OP1 and a first polarizing signal V POL1 for each phase of the transmission line and each representative of the current and voltage conditions existing in each of the phases, said distance measuring relay developing a second operating signal V OP2 and a second polarizing signal V POL2 for each phase of the transmission line and each representative of the current and voltage conditions existing in each of the phases, said protective system further having a first and a second phase angle comparator comprising respectively interconnected first and second AND circuit means and first and second TIMER means, said first AND circuit means being responsive to the phase coincidence between said first operating signal (V OP1 ) and said first polarizing signal (V POL1 ) for developing a first output signal which is routed to and activates said first TIMER means, said first TIMER means generating a first control signal upon the expiration of a first predetermined time duration, said second AND circuit means being responsive to said first control signal and to the phase coincidence between said second operation signal (V OP2 ) and said second polarizing (V POL2 ) signal for developing a second output signal which is routed to and activates the second TIMER means, said second TIMER means generating a second control signal upon the expiration of a second predetermined time duration, each of said first and second control signals being adapted to control circuit breaking means for causing said one or more phases of the one or more zones of the transmission line to be decoupled from the remainder of the transmission line, said protective system further comprising means for developing said V OP1 , V POL1 , V OP2 and V POL2 signals respectively representative of the following relationships: V.sub.OP1 =K.sub.4 {(1+K.sub.5)[(I.sub.P -I.sub.O)Z.sub.R1 +K.sub.O I.sub.O Z.sub.RO -V.sub.PN ]+K.sub.3 V.sub.P1M } (a) where the subscript P shown for the current (I) and voltage (V) quantities is either A, B, or C to indicate the particular phase of the transmission line related to the particular phase of the V OP1 signal; K 3 , K 4 , and K 5 are phase selector relay constants; K O is a zero-sequence line impedance compensation factor substantially equal to the amplitude of the quantity Z LO /Z L1 , where Z LO is equal to the zero-sequence line impedance and Z L1 is equal to the positive-sequence line impedance; I O is the zero-sequence current flowing within the three (3) phase transmission line; Z R1 is the replica positive sequence impedance of the transmission line; Z RO is the replica positive sequence impedance of the transmission line, but with the phase angle of the zero-sequence impedance of the transmission line; I P is representative of the current flowing in the transmission line related to the particular phase of the V OP1 signal; V P1M is the positive sequence component of a prefaulted transmission line voltage related to the particular phase of the V OP1 signal, and; V PN is the phase-to-neutral voltage of the transmission line related to the particular phase of the V OP1 signal; V.sub.POL1 =K.sub.2 V.sub.P1M (b) where K 2 is a phase selector relay constant, and; V P1M is the positive sequence component of the prefaulted transmission line voltage related to the particular phase of the V POL1 signal; V.sub.OP2 =K.sub.8 [(I.sub.P -I.sub.O)Z.sub.R1 +K.sub.O I.sub.O Z.sub.RO -V.sub.PN ] (c) where K 8 is a distance measuring relay constant; K O , I P , I O , V PN , Z R1 and Z RO are as described for expression (a); V.sub.POL2 =K.sub.6 I.sub.P2 X.sub.R -K.sub.7 V.sub.P2 (d) where K 6 and K 7 are distance measuring relay constants; X R is the replica negative sequence reactance of the transmission line; I P2 is the negative sequence component of the current flowing in the transmission line related to the particular phase of the V POL2 signal, and; V P2 is the negative sequence component of the voltage existing in the transmission line related to the particular phase of the V POL2 signal.

Claim 7

A system comprising a phase selector relay and a distance measuring relay both for protecting one or more phases of one or more zones of a high voltage transmission line, said phase selector relay developing a first operating signal V AM1 and a first restraint signal V AM2 for each phase of the transmission line and each representative of the current and voltage conditions existing in each of the phases, said distance measuring relay developing a second operating signal V AM3 and a second restraint signal V AM4 for each phase of the transmission line and each representative of the current and voltage conditions existing in each of the phases, said protective system further having a first and a second amplitude comparator comprising respectively interconnected first and second differential means and first and second TIMER means, said first differential means being responsive to the difference between said first operating signal V AM1 and said first restraint signal V AM2 for developing a first output signal which is routed to and activates said first TIMER means, said first TIMER means generating a first control signal upon the expiration of a first predetermined time duration, said second differential means being responsive to said first control signal and to the difference between said second operating signal V AM3 and said second restraint signal V AM4 for developing a second output signal which is routed to and activates the second TIMER means, said second TIMER means generating a second control signal upon the expiration of a second predetermined time duration, each of said first and second control signals being adapted to control circuit breaking means for causing said one or more phases of the one or more zones of the transmission line to be decoupled from the remainder of the transmission line, said protective system further comprising means for developing said V AM1 , V AM2 , V AM3 and V AM4 signals respectively representative of the following relationships: V.sub.AM1 =1/2(K.sub.2 V.sub.P1M +K.sub.4 {(1+K.sub.5)[(I.sub.P -I.sub.O)Z.sub.R1 +K.sub.O I.sub.O Z.sub.RO -V.sub.PN ]+K.sub.3 V.sub.P1M }) (a) where the subscript P shown for the current (I) and voltage (V) quantities is either A, B, or C to indicate the particular phase of the transmission line related to the particular phase of the V AM1 signal; K 2 , K 3 , K 4 and K 5 are phase selector relay constants; K O is the zero-sequence line impedance compensation factor substantially equal to the amplitude of the quantity Z LO /Z L1 , where Z LO is equal to the zero-sequence line impedance and Z L1 is equal to the positive-sequence line impedance; I O is the zero-sequence current flowing within the three (3) phase transmission line; Z R1 is the replica positive sequence impedance of the transmission line; Z RO is the replica positive sequence impedance of the transmission line, but with the phase angle of the zero sequence impedance of the transmission line; I P is representative of the current flowing in the transmission line related to the particular phase of the V AM1 signal; V P1M is the positive sequence component of a prefaulted transmission line voltage related to the particular phase of the V AM1 signal; and V PN is the phase-to-neutral voltage of the transmission line related to the particular phase of the V AM1 signal; V.sub.AM2 =1/2(K.sub.2 V.sub.P1M -K.sub.4 {(1+K.sub.5)[(I.sub.P -I.sub.O)Z.sub.RO +K.sub.O I.sub.O Z.sub.RO -V.sub.PN ]+K.sub.3 V.sub.P1M }) (b) where the subscript P and the quantities K 2 , K 3 , K 4 , K 5 , K O , I O , Z R1 , Z RO , I P , V P1M and V PN are as given in relationship (a) with the exception that the subscript P is related to the particular phase of the V AM2 signal; V.sub.AM3 =1/2((K.sub.6 I.sub.P2 X.sub.R =K.sub.7 V.sub.P2)+K.sub.8 [(I.sub.P -I.sub.O)Z.sub.R1 +K.sub.O I.sub.O Z.sub.RO -V.sub.PN ]) (c) where K 6 , K 7 and K 8 are distance measuring relay constants; X R is the replica negative sequence reactance of the transmission line; the subscript P shown for the current (I) and voltage (V) quantities is either A, B, or C to indicate the particular phase of the transmission line related to the particular phase of the V AM3 signal; I P2 is the negative sequence component of the current flowing in the transmission line related to the particular phase of the V AM3 signal; V P2 is the negative sequence component of the voltage existing in the transmission line related to the particular phase of the V AM3 signal; and, K O , I P , I O , V PN , Z R1 and Z RO are as described for relationship (a); V.sub.AM4 =1/2((K.sub.6 I.sub.P2 X.sub.R -K.sub.7 V.sub.P2)-K.sub.8 [(I.sub.P -I.sub.O)Z.sub.R1 +K.sub.O I.sub.O Z.sub.RO -V.sub.PN ])(d) where the subscript P and the quantities K 6 , K 7 , K 8 , X R , I P2 , V P2 , K O , I P , I O , V PN , Z R1 and Z RO are as given in expression (c) with the exception that the P subscript is related to the particular phase of the V AM4 signal.

Claim 8

A system comprising a phase selector relay and a distance measuring relay both for protecting one or more phases of one or more zones of a high voltage transmission line, said phase selector relay developing a first operating signal V AM1 and a first restraint signal V AM2 for each phase of the transmission line and each representative of the current and voltage conditions existing in each of the phases, said distance measuring relay developing a second operating signal V AM3 and a second restraint signal V AM4 for each phase of the transmission line and each representative of the current and voltage conditions existing in each of the phases, said protective system further having a first and a second amplitude comparator comprising respectively interconnected first and second differential means and first and second TIMER means, said first differential means being responsive to the difference between said first operating signal V AM1 and said first restraint signal V AM2 for developing a first output signal which is routed to and activates said first TIMER means, said first TIMER means generating a first control signal upon the expiration of a first predetermined time duration, said second differential means being responsive to said first control signal and to the difference between said second operating signal V AM3 and said second restraint signal V AM4 for developing a second output signal which is routed to and activates the second TIMER means, said second TIMER means generating a second control signal upon the expiration of a second predetermined time duration, each of said first and second control signals being adapted to control circuit breaking means for causing said one or more phases of the one or more zones of the transmission line to be decoupled from the remainder of the transmission line, said protective system further comprising means for developing said V AM1 , V AM2 , V AM3 and V AM4 signals respectively representative of the following relationships: V.sub.AM1 =1/2(K.sub.2 V.sub.P1M +K.sub.4 {(1+K.sub.5)[(I.sub.P -I.sub.O)Z.sub.R1 +K.sub.O I.sub.O Z.sub.RO -V.sub.PN ]+K.sub.3 V.sub.P1M }) (a) where the subscript P shown for the current (I) and voltage (V) quantities is either A, B, or C to indicate the particular phase of the transmission line related to the particular phase of the V AM1 signal; K 2 , K 3 , K 4 and K 5 are phase selector relay constants; K O is the zero-sequence line impedance compensation factor substantially equal to the amplitude of the quantity Z LO /Z L1 , where Z LO is equal to the zero-sequence line impedance and Z L1 is equal to the positive-sequence line impedance; I O is the zero-sequence current flowing within the three (3) phase transmission line; Z R1 is the replica positive sequence impedance of the transmission line; Z RO is the replica positive sequence impedance of the transmission line, but with the phase angle of the zero sequence impedance of the transmission line; I P is representative of the current flowing in the transmission line related to the particular phase of the V AM1 signal; V P1M is the positive sequence component of a prefaulted transmission line voltage related to the particular phase of the V AM1 signal; and V PN is the phase-to-neutral voltage of the transmission line related to the particular phase of the V AM1 signal; V.sub.AM2 =1/2(K.sub.2 V.sub.P1M -K.sub.4 {(1+K.sub.5)[(I.sub.P -I.sub.O)Z.sub.RO +K.sub.O I.sub.O Z.sub.RO -V.sub.PN ]+K.sub.3 V.sub.P1M }) (b) where the subscript P and the quantities K 2 , K 3 , K 4 , K 5 , K O , I O , Z R1 , Z RO , I P , V P1M and V PN are as given in relationship (a) with the exception that the subscript P is related to the particular phase of the V AM2 signal; V.sub.AM3 =1/2((K.sub.6 I.sub.P2 X.sub.R =K.sub.7 V.sub.P2)+K.sub.8 [(I.sub.P -I.sub.O)Z.sub.R1 +K.sub.O I.sub.O Z.sub.RO -V.sub.PN ]) (c) where K 6 , K 7 and K 8 are distance measuring relay constants; X R is the replica negative sequence reactance of the transmission line; the subscript P shown for the current (I) and voltage (V) quantities is either A, B, or C to indicate the particular phase of the transmission line related to the particular phase of the V AM3 signal; I P2 is the negative sequence component of the current flowing in the transmission line related to the particular phase of the V AM3 signal; V P2 is the negative sequence component of the voltage existing in the transmission line related to the particular phase of the V AM3 signal; and, K O , I P , I O , V PN , Z R1 and Z RO are as described for relationship (a); V.sub.AM4 =1/2((K.sub.6 I.sub.P2 X.sub.R -K.sub.7 V.sub.P2)-K.sub.8 [(I.sub.P -I.sub.O)Z.sub.R1 +K.sub.O I.sub.O Z.sub.RO -V.sub.PN ])(d) where the subscript P and the quantities K 6 , K 7 , K 8 , X R , I P2 , V P2 , K O , I P , I O , V PN , Z R1 and Z RO are as given in expression (c) with the exception that the P subscript is related to the particular phase of the V AM4 signal.