Claims
- 1. In a short-circuit distance relay for protecting a single-channel power transmission system with a transmission line of length L and local and remote power supplies installed at the respective two ends of the transmission line, the improvement comprising:
- first and second deriving means for respectively deriving values of a positive-phase voltage (V) and a positive-phase current (IL) at the location of said relay at the local end of the transmission line during a normal state of the system;
- third, fourth and fifth deriving means for respectively deriving values of a positive-phase voltage (VF), a positive-phase current (IF) and a negative-phase current (I2) at the location of said relay during a fault state of the system;
- a first memory circuit with selector switch means operated in response to detection of a fault for storing the derived value of the positive phase voltage (V) during a normal state of the system and for storing the derived value of the positive phase voltage (VF) during a fault state of the system;
- a second memory circuit with selector switch means operated in response to detection of a fault for storing the derived value of a positive phase current (IL) during a normal state of the system and for storing the derived value of a positive phase current (IF) during a fault state of the system; and
- arithmetic and computation means for obtaining the fault impedance (XZ1) between the location of the relay and the point of fault in accordance with the following formula: ##EQU14## where: (ZP+ZQ) is a sum of predetermined positive phase impedance of the system,
- LZ2 is a predetermined negative phase impedance of the power transmission line, and
- ZQ2 is a predetermined negative phase impedance behind the remote end.
Priority Claims (1)
Number |
Date |
Country |
Kind |
59-35292 |
Feb 1984 |
JPX |
|
Parent Case Info
This is a continuation of application Ser. No. 676,304 filed Nov. 29, 1984, now abandoned.
US Referenced Citations (15)
Foreign Referenced Citations (3)
Number |
Date |
Country |
0106790 |
Jun 1983 |
EPX |
2932929 |
May 1980 |
DEX |
2036478 |
Jun 1980 |
GBX |
Non-Patent Literature Citations (2)
Entry |
"Protective Relays" by A. R. van C. Warrington, pp. 270-274 (1969). |
"Applied Protective Relaying", Westinghouse Electric Corporation, pp. 10-34, 10-42, 10-43 and 10-44 (1976). |
Continuations (1)
|
Number |
Date |
Country |
Parent |
676304 |
Nov 1984 |
|