| 摘要 |
PURPOSE:To make it possible to set a distance relay coordinated with a protective equipment on the power transmission line side by changing the value of an input voltage of the distance relay by using a resistor depending on the operating conditions of other generators. CONSTITUTION:If a plurality of generators T, 8 and 9 are connected to a power transmission bus 3, a current 12 decreases so that an impedance 2 seen from the distance relay 10 becomes larger than the line impedance up to the actual short-circuit point. At this time, among the inputs of short-circuit back-up protection distance relay 10, the voltage of the distance relay 10 is reduced by resistors 25 to 27 having respectively different resistance values switched by auxiliary contacts 19 to 20 of the generators 7, 8 and 9 in an input circuit of voltage (PT secondary voltage) as generator information, by which the value of generator voltage V seen from the distance relay is virtually made smaller in response to the change in T1, and the result V/11 is made constant. In this way, by making constant the impedance seen from the distance relay 10, the protection range can be made constant regardless of the number of operating units of generators. |
