Tài liệu về " điện tử cơ bản " 20 kết quả
dielectrics in electric fields (10)
. corona
discharge continue
to
draw interest. Corona
is a
self sustained electrical discharge
in a
gas
where
the
Laplacian electric
field
confines
the
. inception voltages increases with increasing
divergence
of the
electric
field. The
corona
from
a
positive point
is
predominantly
in the
form
of
dielectrics in electric fields (11)
. of the
material; retrapping
is
dominant
in
dielectrics
whereas
recombination
with
light
output
dominates
in
thermoluminiscent
materials.
Conduction. that
at E. The
trapping level, having
a
single energy
level
c, and a
single retrapping center (Fig.
10.1)
shows
a
single peak
in the
measured
current
dielectrics in electric fields (12)
. move
a
certain distance within
the
dielectric, building
up a
space charge density
and an
internal
electric
field
which
may be
quite intense
to
. current,
I=dielectric
current (Gross
et.
al.
1973, with permission
of A.
Inst.
Phys.).
The
increase
in
internal electric
field
leads
to an
increase
electric machinery
. rank of Professor of Electrical
Engineering. Besides
Electric Machinery,
Professor Fitzgerald was one of the au-
thors of
Basic Electrical Engineering,. and Sc.D. degrees, all in electrical engineering. His professional interests
include electromechanics, electric machinery, and electric power systems. At
electric power generation, transmission, and distribution ( (2)
.
Anti-Motoring
Protection (3 2)
.
Overexcitation Protection (2 4)
.
Overvoltage (5 9)
.
Voltage
Imbalance Protection (6 0)
.
System Backup Protection (5 1V and 21)
.
Out-of-Step. Transformer core flux density (B), induced voltage (V), and
frequency (f) are related by the following formula.
B ¼ k
1
Á
V
f
(1 :1)
where K
1
is a constant
electric power generation, transmission, and distribution ( (3)
. Imbalance (4 6) 2-6
2.7 Anti-Motoring Protection (3 2) 2-8
2.8 Overexcitation Protection (2 4) 2-9
2.9 Overvoltage (5 9) 2-10
2.10 Voltage Imbalance Protection (6 0). reverse power gets as low as 0.2 to 2% of the rated power
and a sensitive reverse power relay is then needed. With steam turbines operating at full vacuum and
zero
electric power generation, transmission, and distribution ( (4)
. between phases a and b. In general, for a
multiphase fault between phases x and y,
Ex À Ey
Ix À Iy
¼ Z
1
(3 :1)
where x and y can be a, b, or c and Z
1
is the. protection chain. On High Voltage (HV)
and EHV systems, the costs of transducers and circuit breakers are very expensive and the cost of
duplicate equipment
electric power generation, transmission, and distribution ( (5)
. plane (a bold curve). It can be
observed that: (a) there may be many possible trajectories to (and points of) voltage collapse; (b) active
and reactive power. the load voltage V when active (P) and reactive (Q) powers change
independently. It also shows the active and reactive power margins as projections of
electric power generation, transmission, and distribution ( (6)
. Eq. (5 .38)
ð
t
2
t
1
v(t)dt À L[i(t
2
) À i(t
1
)] ¼ L(t
2
) À L(t
1
)(5 :39)
gives
L(t
2
) À L(t
1
) ¼
T
2
[v(t
2
) þ v(t
1
)] ÀL[i(t
2
) À i(t
1
)] (5 :40)
or
L
kþ1
¼. integrals (assuming t is small)
ð
t
2
t
1
v(t)dt ¼ R
ð
t
2
t
1
i(t)dt þ L(i(t
2
) À i(t
1
)) (5 :33)
ð
t
2
t
1
v(t)dt ¼ R
ð
t
2
t
1
i(t)dt þ L(i(t
2
) À i(t
1
))
electric power generation, transmission, and distribution ( (7)
. during the fault (good) permitting
high-speed tripping at both terminals (breakers A and B). There is no evidence of AC or DC current
transformer (CT) saturation. good (A)
or questionable (B) as shown in Fig. 6.2. The first fault current waveform (upper left) is classified as A
because it is sinusoidal in nature and
electric power generation, transmission, and distribution ( (8)
. l Stability and Power System Oscillations John Paserba, Juan
Sanchez-Gasca, Prabha Kundur, Einar Larsen, and Charles Concordia 9-1
Nature of Power System. restore power
consumption beyond the capability of the transmission system and the connected generation (Kundur,
1994; Taylor, 1994; Van Cutsem and Vournas,
electric power generation, transmission, and distribution ( (9)
. given by Eq. (8 .7) and interchanging per unit power for torque
d
2
d
dt
2
¼
v
0
2H
( P
m
À P
e
)(8 :10)
Multiplying both sides by 2d=d t and integrating. section.
Two concepts are essential in understanding transient stability: (i) the swing equation and (ii) the
power angle relationship. These can be used
electric power generation, transmission, and distribution ( (10)
. (1 996), CIGRE
Technical Brochure No. 116 (2 000), and Kundur (1 994), as well as Gibbard et al. (2 001) and IEEE
PES (2 000, 2002, 2003, 2005) contain information. reduced-order
modeling and modal analysis for power system response signals, IEEE Trans. Power Systems, 8(3 ),
1020–1029, 1993.
Kundur, P., Power System Stability and Control,
electric power generation, transmission, and distribution ( (11)
. model (Xu and Mansour, 1994), x is the state variable. P
t
( V ) and P
s
( V ) are
the transient and steady-state load characteristics, respectively, and. P
s
(V ) À P, P ¼ xP
t
(V )
T
q
dy
dt
¼ Q
s
(V ) À Q, Q ¼ yQ
t
(V )
P
t
(V ) ¼ V
a
, P
s
(V ) ¼ P
o
V
a
; Q
t
(V ) ¼ V
b
, Q
s
(V ) ¼ Q
o
V
b
10.1.3 Effect
electric power generation, transmission, and distribution ( (12)
. in Padiyar and
Sastry (1 987), Padiyar and Ghosh (1 989), and Abu-Elnaga et al. (1 988).
In Chiang (1 985), Chiang et al. (1 987), and Chiang et al. (1 988), a. methods: Pai (1 981), Pai
(1 989), Fouad and Vittal (1 992), Ribbens-Pavella (1 971), and Pavella and Murthy (1 994). These
references provide a thorough and detailed
electric power generation, transmission, and distribution ( (13)
. fault
Postdisturbance
Δw
P
m
P
(a)
(b)
δ
δ
d
o
p
p −d
′
o
p −d ′
o
d
o
d ′
o
d ′
o
Predisturbance
electrical power
FIGURE 12.4 (a) Power angle curve and equal area criterion series compensator (SSSC), unified power flow
controller (UPFC), and interline power flow controller (IPFC). The convertible static compensator
(CSC) allows multiple
electric power generation, transmission, and distribution ( (14)
. (HVDC)
systems (Kundur, 1994) and power electronic (PE) devices. The latter includes static VAr compensators
(SVC) (IEEE Transactions, February 1994) and. current
limiter
Overexcitation
limiter (OEL)
Voltage sensing
and compensation
Underexcitation
limiter (UEL)
Generator flux
(Volts/Hertz)
limiter
Power, frequency,
or
other signals
Power
system
stabilizer
Rotor
electric power generation, transmission, and distribution ( (15)
. optimistic.
Controller input y
m
(t)
Load noise u
L
(t)
Set point changes r(t)
Unmeasured response y 9(t)
Actuator output u(t)
Measured response y(t)
Extraneous
signals
Measurement
noise. y(t)
Extraneous
signals
Measurement
noise u
m
(t)
Nonlinear
interactions
Actuator
Actuator noise υ
u
(t)
Linear response u(t)
Nonlinear response u(t)
Power
system
Sensors
and
Transducers
Processing
artifact...
electric power generation, transmission, and distribution ( (16)
. the following equations:
dd
dt
¼ v À v
s
(1 5:1)
dv
dt
¼ f (v, x, y) (1 5:2)
dx
dt
¼ g(v, x, y) (1 5:3)
0 ¼ h(d, x, y) (1 5:4)
In addition, the algebraic equations. assessment (DSA). DSA has been
formally defined by the Institute of Electrical and Electronics Engineers (IEEE), Power Engineering
Society’s (PES), working
electric power generation, transmission, and distribution ( (17)
. Introduction
Turbine-generators for power production are critical parts of electric power systems, which provide power
and energy to the user. The power system can range. be in
synchronism and there is no dynamic interaction between the power system and the turbine-generators.
At other times, the system and its components