Question

Question: Determine the sub transient fault current in per-unit and in kA during a bolted three-phase fault at the fault bus selected in Problem 9.2.

Short answer

Answer

The sub transient fault current in per unit and kA are$\left[\begin{array}{c}9.363<{90}^0\\ 9.363<{150}^0\\ 9.363<{30}^0\end{array}\right]pu$ and$\left[\begin{array}{c}7.067<-{90}^0\\ 7.067<-{150}^0\\ 7.067<-{30}^0\end{array}\right]$ respectively.

Step-by-step solution

Write the given data from the question

Write the rating of the generators.

The power rating of generator is G₁ 1000 MVA, the voltage rating is 15 KV, the reactance X_d^''and X₀ are equal to 0.18 per unit , and the value of X₀ is 0.07 per unit.

The power rating of generator is G₂ 1000 MVA, the voltage rating is 15 KV, the reactance X_d^''and X₀ are equal to 0.20 per unit , and the value of X₀ is 0.10 per unit.

.The power rating of generator is G₃ 500 MVA, the voltage rating is 13.8 KV, the reactance X_d^''and X₀ al to 0.18 per unit , and the value of X₀ is 0.05 per unit.

.

The power rating of generator is G₄ 750 MVA, the voltage rating is 15 KV, the reactance X_d^'' i s 0.30 and X₂ is 0.40 per unit , and the value of X₀ is 0.10 per unit.

Write the rating of the transformer.

The power rating of transformer T₁ is 1000 MVA, the voltage rating is , and the value of is .

The power rating of transformer is , the voltage rating is, and the value of is .

The power rating of transformer is , the voltage rating is, and the value of is .

The power rating of transformer is , the voltage rating is, and the value of is .

Write the rating of transmission.

The voltage rating of transmission line is , reactance is , and is .

The voltage rating of transmission line is , reactance is , and is .

The voltage rating of transmission line is , reactance is , and is .

The neutral reactance of the generator 3, .

The base MVA, .

The base voltage, .

The pre fault voltage, .