| 申論題 | 1.A 230/115-V, 1-kVA transformer has been tested to determine its equivalent circuit. The results of
the tests are shown below. 【題組】 (a)Calculate the parameters and draw the equivalent circuit of this transformer referred to the low- voltage side of the transformer. (15%) |
| 申論題 | 【題組】(b)Calculate the voltage regulation at rated conditions with Power Factor (PF) 1.0. (5%) |
| 申論題 | 2.A power station consists of four 100-MVA, 69-kV, 0.9-PF lagging synchronous generators operating
in parallel with identical speed droop characteristics. The governors on the generators' prime movers
are adjusted to produce a 3-Hz drop from no load to full load. Three of these generators are each
supplying a steady 75 MW at a frequency of 60 Hz, while the fourth generator handles all
incremental load changes on system while maintaining the system's frequency at 60 Hz. 【題組】 (a)The total system loads are 260 MW at a frequency of 60 Hz. Calculate the no-load frequencies of each generator. (10%) |
| 申論題 | 【題組】(b)Calculate the new system frequency if the system load rises to 290 MW. (10%) |
| 申論題 | 3. The fuel cost function in $/h for four units of a plant are |
| 申論題 | 4. The following equations are the real power and reactive power injected into a bus:
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| 申論題 | 5.A three-phase, 60-Hz, 250-MVA, 13.8-kV, generating unit has an H constant of 4.0 p.u.-s. The mechanical power supplied by prime mover and electrical power output of the generator in p.u. are pm and pe, respectively. Initially, this unit is operating synchronously at pm =pe =2.0 with power angle δ=10°. 【題組】 (a) Give the per-unit swing equation for this unit. (5%) |
| 申論題 | 【題組】(b) Calculate the power angle 4 cycles after a short circuit causes pe = 0.(10%) |
| 申論題 | 1. Fig. 1 shows a simple loop rotating in a uniform magnetic field. It has the following characteristics
(25%): 【題組】 (a) Calculate the voltage induced in the rotating loop (  ) and the current flowing through the
resistor. (10%)
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| 申論題 | 【題組】(b) Calculate the induced torque, electric power being generated and mechanical power being consumed by the loop. (15%) |
| 申論題 | 2. Calculate the geometric mean radius of conductors shown in Fig. 2 in terms of the radius r of an
individual strand. (10%) |
| 申論題 | 3. Discuss the solution procedures for a power flow problem solved by a Netwon-Raphson technique. (including the procedure for swing bus, PV bus and PQ bus) (15%) |
| 申論題 | 4. The impedance matrix ( |
| 申論題 | 5. Derive the solution for the following economic dispatch problem by Lagrangian multiplier (15%) |
| 申論題 | 6.Assume that the impedances for zero-sequence, positive-sequence and negative-sequence networks are Z0, Z1 and Z2 , respectively. Derive the formulas for I0, I1 , I2, and Ia and draw the interconnected sequence networks for a single line-to-ground fault as shown in Fig. 3 (20%) |
| 申論題 | 1. The impedance matrix (ZBus) for Fig.I can be expressed as eq. (1). (25%) 【題組】 (a) Calculate the Z matrix after the line between Bus 2 and Bus 4 is removed； (15%) |
| 申論題 | 【題組】(b) Assuming the bus voltages before fault are all 1.0p.u. Calculate the short circuit current when a three-phase short-circuit fault occurred at Bus 3 for (a) and bus voltages after this fault. (10%) |
| 申論題 | 2.A Y-connected load bank with a three-phase rating of 1000 kVA and 1150 V consists of three
identical resistors of 1.3225 ohms. The load bank has the following applied voltages:
【題組】 (a) the zero-, positive- and negative-sequence line-to-neutral voltages |
| 申論題 | 【題組】 (b) the zero-, positive- and negative-sequence line-to-line voltages |
| 申論題 | 【題組】 (c) the zero-, positive- and negative-sequence line currents |
| 申論題 | 3.Calculate the line flows and power flows from Bus i to Bus j and Bus j to Bus i for Fig. 2 and the line
loss for this line (all values in Fig. 2 are in p.u.). (20%)
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| 申論題 | 4. The inertia constant (H) of a three-phase 60-Hz generator is 1.5 p.u.-s. The electrical power delivery by the generator (Pe) versus its power angle (δ ) can be expressed as eq. (2). The mechanical power input to the generator ( Pm) is 0.5 p.u. (25%) Pe=1.2319sin(δ) 【題組】 (a) Determine the swing equation and the initial operating power angle. (10%) |
| 申論題 | 【題組】(b) Calculate the critical clearing time for the generator when a three-phase bolted short-circuit at the generator terminals causes Pe =0. (15%) |
| 申論題 | 5. Draw the phasor diagrams between the voltages and current of a synchronous generator of 【題組】 (a) unity power factor, |
| 申論題 | 【題組】(b) lagging power factor and |
| 申論題 | 【題組】(c) leading power factor. (15%) |
Assume that all four units operate economically to meet the total plant load of 700MW, find the
incremental cost of the plant and the required output of each unit (20%).
Calculate the derivatives of
for Newton-Raphson Load FIow.(25%) 
) of a power system is
=920∠2.8° , 
=1380∠-41.4° , and 
=11502180 V. Determine (15%)
； (5%)
； (5%)
. (5%)
(All answers should be in p.u.)
