代写EEE 471/591: Power System Analysis [Face-to-Face] Homework #2帮做R程序

EEE 471/591: Power System Analysis [Face-to-Face]

Homework #2

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Problem 1 (16 Points)

A balanced three-phase 240-V source supplies a balanced three-phase load. If the line current IA is measured to be 15A and is in phase with the line-to-line voltage VBC, find the per-phase load impedance if the load is (a) Y-connected, (b) Δ-connected.

Problem 2 (16 Points)

A three-phase 25-kVA, 480-V, 60-Hz alternator, operating under balanced steady-state conditions, supplies a line current of 20 A per phase at a 0.8 lagging power factor and at rated voltage. Determine the power triangle for this operating condition.

Problem 3 (17 Points)

Two balanced three-phase loads that are connected in parallel are fed by a three-phase line having a series impedance of (0.4 + j2.7) Ω per phase. One of the loads absorbs 560 kVA at 0.707 power factor lagging, and the other 132 kW at unity power factor. The line-to-line voltage at the load end of the line is 2200√3 V. Compute (a) the line-to-line voltage magnitude (in RMS value) at the source end of the line, (b) the total real and reactive power losses in the three-phase line, and (c) the total real and reactive power supplied at the sending end of the line.

Problem 4 (17 Points)

Two balanced Y-connected loads in parallel, one drawing 15kW at 0.6 power factor lagging and the other drawing 10kVA at 0.8 power factor leading, are supplied by a balanced, three-phase, 480-volt source. (a) Draw the power triangle for each load and for the combined load. (b) Determine the power factor of the combined load and state whether lagging or leading. (c) Determine the magnitude of the line current from the source. (d) Δ-connected capacitors are now installed in parallel with the combined load. What value of capacitive reactance is needed in each leg of the A to make the source power factor unity? Give your answer in Ω. (e) Compute the magnitude of the current in each capacitor and the line current from the source.

Problem 5 (17 Points)

Determine the 4 × 4 bus admittance matrix Ybus and write nodal equations in matrix format for the circuit shown in Figure 1. Do not solve the equations.

Figure 1. Circuit for Problem 5

Problem 6 (17 Points)

Given the impedance diagram of a simple system as shown in Figure 2, draw the admittance diagram for the system and develop the 4 × 4 bus admittance matrix Ybus by inspection. All the values shown in Figure 2 are line impedance values in Ω. The two circles at bus 1 and bus 2 represent synchronous generators (constant voltage sources in the ac circuit).

Figure 2. Circuit for Problem 6