Chapter 14, Problem 22P

Select a short-circuit withstanding (1-second short circuit length) cable for Feeder 1 in Figure 1. Values for cables are given in Table 1. The voltage of the supplying network is now 115 kV and the short-circuit power of the supplying network is 2000 MVA. Table 1. Technical information of 3-phase cables (10 kV and 20 kV) Product's name EA-number Structural information 20KV 20KV 20 KV 0624250 0624252 0624253 0624254 AHKAMK-W AHKAMKW AHKAMKWAHKAMKW AHKAMKW AHKAMKW AHKAMKW 3x50Al+35Cu 3x95 Al. 35Cu 3x120Al. 35Cu 3x150Al+35Cu 3x185Al+35Cu 3x240A1+70 Cu 3x300Al+70Cu 20kV 20kV 20 kV (8) 20KV 0624255 0624257 0624256 Diameter of conductor Diameter of out-most circle Cable's outer diameter Mass Delivery information Standard length Delivery reel mm 8.0 11.3 12.7 14.1 15.7 18.1 20.3 mm 28 32 34 35 37 40 43 mm 64 71 74 76 80 89 94 aluminium kg/km 510 910 1100 1350 1650 2200 2700 сорраг kg/km 305 305 305 305 305 600 600 cable kg/km 2350 3100 3450 3800 4300 5500 6250 E 500 500 500 500 500 500 500…

A three-phase 20 kV medium-voltage line is 10 km. Resistance is 0.252 2/km and reactance is 0.128 92/km (inductive). Voltage at the beginning of line is 21.0 kV. At the end of the line is loading P = 2.5 MW with power factor 0.92ind. Draw 1-phase equivalent diagram and calculate line voltage at the end the of line, active and reactive power at the beginning of the line and power losses of the line.

A three-phase 20 kV medium-voltage line is 10 km. Resistance is 0.365 2/km and reactance is 0.363 2/km (inductive). Voltage at the beginning of line is 20.5 kV. At the end of the line is loading P= 800 kW with power factor 0.95ind. Draw 1-phase equivalent diagram and calculate load current, line voltage at the end the of line, voltage drop and power losses of the line.

6. Answer the following questions. Take help from ChatGPT to answer these questions (if you need). Write the answers briefly using your own words with no more than two sentences, and make sure you check whether ChatGPT is giving you the appropriate answers in our context. A) What is a model in our context? B) What is an LTI system? C) What are the three forms of model we have used in the class so far to represent an LTI system? Among the above three forms, which forms can still be used to represent a nonlinear system?

5. Consider the following block diagram of a system in the Figure 4. Y₁(s) G₁ G2. R(s) C(s) Y₂(s) G3 G4 Figure 4 The models of the blocks G1, G2, G3 and G4 are represented by a differential equation, transfer function, state-space form, and impulse response as the followings. dy1 G₁: +2y₁ = 3r(t) dt 1 G2: G₂(s) = S+3 G3: x=2x+r, y2=3x-r G4: h(t)=8(t) + et 1(t) Find the simplified expression of the overall transfer function of the system i.e., G(s) = Note for G3 block, you may need to use the formula H(s) = C (sI - A)-¹ B+ D. C(s) R(s)

4. Simplify the block diagram in Figure 3 and find the closed-loop transfer function G(s) = C(s) R(s) G₁ R(s) Figure 3 C(s) G2 H₁ H₂

1. Consider a system defined by the following state-space equations. -5 2 N-MAN-G = 3 -1 y = [12] Find the transfer function H(s) = x1 x2. Y(s) U(s)' + 5

3. Simplify the block diagram in Figure 2 and find the closed-loop transfer function G(s) = C(s) R(s)' G₁ C(s) R(s) G2 G3 G4 Figure 2

Rigid network supplies Feeder 1 through 110/21 kV transformer (Figure 1). Short circuit power of the supplying network is 5000 MVA and voltage is 110 kV. Determine 3-phase short circuit current for the point A. Draw 1-phase equivalent diagram. How big is the current if the 3-phase short circuit occurs in the Busbar? 110/21 kV Busbar Supplying network S = 16MVA 4-10% Figure 1. Feeder 1: 1-5km - r = 0.337 2/km x 0.361 2/km A