课程名称︰电力工程导论
课程性质︰电机工程学系复选必修暨离岸风力发电学分学程进阶专业选修课程
课程教师︰刘志文
开课学院：电机资讯学院
开课系所︰电机工程学系
考试日期（年月日）︰2020/4/21
考试时限（分钟）：14:20-16:50
试题 : 1-6题 每题10分，第7题15分，第8题25分
1. In Figure 1, v(t) = √2 × 120cos(ωt + 30°)
i(t) = √2 × 10cos(ωt － 30°)
(a) Find p(t), S, P, and Q into the network.
(b) Find a simple (two-element) series circuit consistent with the
prescribed terminal behavior as described in this problem.
Fig.1 https://imgur.com/AMluD69
2. A 1φ load draws 10kW from a 416-V line at a power factor of 0.9 lagging.
(a) Find S = P ＋ jQ.
(b) Find │I│.
(c) Assume that ∠I = 0 and find p(t).
3. In Figure 2, find the total complex power delivered to the load.
Assume that ZC = －j0.2
ZL = j0.1
R = 10
Fig.2 https://imgur.com/SGg3sKu
4. In the system shown in Figure 3, find Ia, Ib, Ic if
(a) Za = Zb = j1.0, Zc = j0.9
(b) Za = Zb = Zc = j1.0
Hint: Use per phase analysis in part (b)
Fig3. https://imgur.com/npT0iAw
5. The system shown in Figure 4 is balanced. Find Va'n, Vb'n, Vc'n, and Va'b'
Fig4. https://imgur.com/Kx1SpcH
6. The system shown in Figure 5 is balanced. Assume that
load inductors, ZL = j10
load capacitors, ZC = －j10
3φ
Find Ia, Icap, and S .
load
Fig5. https://imgur.com/x0XnWIH
7. In Figure 6, assume that
Ea = √2∠45°
Eb = 1∠-90°
Ec = 1∠180°
Ia = 1∠-10°
Fig6. https://imgur.com/gY65wze
The load is symmetrical and Z is not given. The sources are not balanced,
3φ
but we noted that Ea + Eb + Ec = 0. Find S .
load
8. Justify the formula l = 4 × 10^(－7)ln(D/r') henrys per meter for the round
-trip inductance of a single-phase line made up of round wires of radius r
separated by a distance D between centers. For simplicity, assume that
D＞＞r and make reasonable simplifications. Note that the inductance "per
conductor" is the same as the per phase inductance of a three-phase line,
but the inductance is doubled because there are two conductors.