Automatic fault location system

• US 5,455,776 A
• Filed: 09/08/1993
• Issued: 10/03/1995
• Est. Priority Date: 09/08/1993
• Status: Expired due to Term

• Current Assignee: ABB Power T&D Limited (ABB Limited)
• Original Assignee: ABB Power T&D Limited (ABB Limited)
• Inventors: Novosel, Damir
• Primary Examiner(s): Ramirez, Ellis B.
• Assistant Examiner(s): Assouad, Patrick J.
• Application Number:
  US08/118,000
• Time in Patent Office: 755 Days
• Field of Search: 364/492, 364/483, 364/481, 324/51, 324/52, 324/509, 324/521, 340/870.28, 340/662, 361/80, 361/85, 361/86, 361/88
• US Class Current: 702/59
• CPC Class Codes: G01R 31/088 Aspects of digital computing

Abstract

A fault location system comprises voltage/current transducers 10A, 10B located at terminals A and B, respectively; digital relays 12A and 12B respectively coupled to transducer blocks 10A and 10B; and a fault location estimation processor 14, which may comprise a substation controller at substation S_A or substation S_B, a relay at A or B, a stand alone computer at A or B, or a computer at a central location. The digital relays receive analog voltage and current signals (V_A, I_A, V_B, I_B) from the respective transducers and output digital phasor or oscillographic data to the fault location estimation block. The fault location estimation block is programmed to provide the fault location parameter m. The fault location estimation provided by the inventive technique is unaffected by the fault resistance, load current, mutual coupling effects from a parallel line, uncertainties in zero sequence values, shunt elements, and X/R characteristic of the system. The fault location can be estimated accurately even in cases of substantial resistance and load flow. In addition, the invention does not require synchronization of the data received from the respective A and B terminals, nor does it require pre-fault data or fault type selection.

Claims

1. A fault location system for locating a fault associated with one or more conductors of an electric power transmission or distribution system, comprising:

a first transducer set for measuring a first voltage (V_A) and a first current (I_A), at a first prescribed location on at least one conductor;

a second transducer set for measuring a second voltage (V_B) and a second current (I_B) at a second prescribed location on said at least one conductor;

(c) a first relay, coupled to said first transducer set, for generating data (V_Af, I_Af), indicative of an amplitude and phase of said first voltage and current;

(d) second relay, coupled to said second transducer set, for generating data V_Bf, I_Bf) indicative of an amplitude and phase of said second voltage and current; and

(e) a fault location estimation processor, coupled to said first and second relays, for generating a fault location parameter m indicative of the location of the fault;

wherein m is obtained from one of the following equations;

##EQU8## wherein δ

represents a phase difference between said first and second voltages, A is a real number having a value which is a first predetermined function of I_Af and a resistance and reactance of said at least one conductor, B is a real number having a value which is a second predetermined function of I_Af and said resistance and reactance of said at least one conductor, C is a real number having a value which is a first predetermined function of I_Bf and said resistance and reactance of said at least one conductor; and

D is a real number having a value which is a fourth predetermined function of I_Bf and said resistance and reactance of said at least one conductor.

2. A fault location system as recited in claim 1, wherein δ

is obtained from the equations;

##EQU9##

space="preserve" listing-type="equation">F(δ

.sub.k)=b* cos δ

.sub.k +a* sin δ

.sub.k +C

space="preserve" listing-type="equation">F'"'"'(δ

.sub.k)=a* cos δ

.sub.k -b* sin δ

.sub.k

space="preserve" listing-type="equation">a=-C*Re(V.sub.Af)-D*Im(V.sub.Af)-A*Re(V.sub.Bf)-B*Im(V.sub.Bf)+AC+BD

space="preserve" listing-type="equation">b=D*Re(V.sub.Af)-C*Im(V.sub.Af)-B*Re(V.sub.Bf)+A*Im(V.sub.Bf)+BC-AD

space="preserve" listing-type="equation">c=B*Re(V.sub.Af)-A*Im(V.sub.Af)-D*Re(V.sub.Bf)+C*Im(V.sub.Bf).

3. A fault location system as recited in claim 2, wherein A, B, C, and D are obtained from:

space="preserve" listing-type="equation">A=R*Re(I.sub.Af)-X*Im(I.sub.Af)

space="preserve" listing-type="equation">B=R*Im(I.sub.Af)+X*Re(I.sub.Af)

space="preserve" listing-type="equation">C=R*Re(I.sub.Bf)-X*Im(I.sub.Bf)

space="preserve" listing-type="equation">D=R*Im(I.sub.Bf)+X*Re(I.sub.Bf).

5. A fault location system as recited in claim 2, wherein said fault location processor determines whether compensation is required to parameter m for compensating for long conductors in the electric transmission or distribution system by computing A, B, C, and D from:

space="preserve" listing-type="equation">A=R.sub.A *Re(I.sub.Af)-X.sub.A *Im(I.sub.Af)

space="preserve" listing-type="equation">B=R.sub.A *Im(I.sub.Af)+X.sub.A *Re(I.sub.Af)

space="preserve" listing-type="equation">C=R.sub.B *Re(I.sub.Bf)-X.sub.B *Im(I.sub.Bf)

space="preserve" listing-type="equation">D=R.sub.B *Im(I.sub.Bf)+X.sub.B *Re(I.sub.Bf)

wherein R_A, R_B, X_A, and X_B are resistance and reactance values.

4. A fault location system for locating a fault associated with one or more conductors of an electric power transmission or distribution system, comprising:

(a) a first transducer set for measuring a first voltage (V_A) and a first current (I_A) at a first prescribed location on at least one conductor;

(b) a second transducer set for measuring a second voltage (V_B) and a second current (I_B) at a second prescribed location on said at least one conductor;

(c) a first relay, coupled to said first transducer set, for generating data (V_Af, I_Af) indicative of an amplitude and phase of said first voltage and current;

(d) a second relay, coupled to said second transducer set, for generating data (V_Bf, I_Bf) indicative of an amplitude and phase of said second voltage and current;

(e) a fault location estimation processor, coupled to said first and second relays, for generating a fault location parameter m indicative of the location of the fault and

for determining whether compensation is required of parameter m to compensate for long conductors in the electric transmission or distribution system;

wherein m is obtained from one of the following equations;

##EQU10## wherein δ

represents a phase difference between said first and second voltages, A is a real number having a value which is a first predetermined function of I_Af and a resistance and reactance of said at least one conductor, B is a real number having a value which is a second predetermined function of I_Af and said resistance and reactance of said at least one conductor, C is a real number having a value which is a first predetermined function of I_Bf and said resistance and reactance of said at least one conductor, and D is a real number having a value which is a fourth predetermined function of I_Bf and said resistance and reactance of said at least one conductor.

6. A fault location system for locating a fault associated with one or more conductors of an electric power transmission or distribution system, comprising:

(a) a first transducer set for measuring a first voltage (V_A) and a first current (I_A) at a first prescribed location on at least one conductor;

(b) a second transducer set for measuring a second voltage (V_B) and a second current (I_B) at a second prescribed location on said at least one conductor;

(c) a first relay, coupled to said first transducer set, for generating data (V_Af, I_Af) indicative of an amplitude and phase of said first voltage and current;

(d) a second relay, coupled to said second transducer set, for generating data (V_Bf, I_Bf) indicative of an amplitude and phase of said second voltage and current;

(e) a fault location estimation processor, coupled to said first and second relays, for generating a fault location parameter m indicative of the location of the fault; and

for determining whether compensation is required of parameter m to compensate for shunt elements in the electric transmission or distribution system;

wherein m is obtained from one of the following equations;

##EQU11## wherein δ

represents a phase difference between said first and second voltages, A is a real number having a value which is a tint predetermined function of I_Af and a resistance and reactance of said at least one conductor, B is a real number having a value which is a second predetermined function of I_Af and said resistance and reactance of said at least one conductor, C is a real number having a value which is a first predetermined function of I_Bf and said resistance and reactance of said at least one conductor, and D is a real number having a value which is a fourth predetermined function of I_Bf and said resistance and reactance of said at least one conductor.