= Calculation (a total of 2 sub questions, a total of 40 points) 1 (25 points) As shown in the below figure, Known: posi

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Calculation A Total Of 2 Sub Questions A Total Of 40 Points 1 25 Points As Shown In The Below Figure Known Posi 1 (64.7 KiB) Viewed 17 times

= Calculation (a total of 2 sub questions, a total of 40 points) 1 (25 points) As shown in the below figure, Known: positive sequence impedance of network Z₁ = 0.4 2/km, line impedance angle q = 65 °, Bus A and B are equipped with two-stage distance protection, and the measuring elements of sections I and II adopt directional impedance relay. Try: (1) Action values of section I and II of distance protection in substation a (both the reliability coefficient of section I and II are 0.8). = (2) When phase to phase short circuit occurs at 55km and 65km away from bus A on the line AB, judge the action of protection in each section of substation a. (3) If the voltage of bus a is 115kV and the load power factor passing through the Bus is 0.9, how much load current will lead to the misoperation of the distance protection section II? C 75kn 50kn The figure of the first subquestion 2 Calculate the setting value and sensitivity (minimum protection range) of current quick break protection of 35kV line AB in the figure below. It is known that the maximum impedance of the system is 10 92, the minimum impedance is 8 22, the reliability coefficient is 1.2, the impedance of AB line is Z1 = 0.4 2/km, 1= 30km. (E=37/√3 kV) ). (20 points) Ⓒ+ The figure of the second subquestion