... resistance of the conductors and leads.
ã Eddy losses. These losses are caused by the leakage field, and they are a function of thesecond power
of the leakage field density and thesecondpower of the conductor ... is placed in the field created by the first conductor as shown
in Fig. 3.2, such that the flux lines link thesecond conductor, then a voltage is induced into the second
conductor. The use of a ... increases
the cooling and thereby the rating of the transformer without increasing the unit’s physical size. Ratings
are determined based on the temperature of the unit as it coordinates with the cooling...
... system.
The figure shows the Phoenix area 230-kV system, which interconnects the local power plants and the
substations supplying different areas of the city. The circles are the substations and the ... to move out on the line to replace the spacer,
or the line would have been lowered and the spacer replaced and the conductor strengthened. The obvious
safety dilemma was whether the conductor ... erosion, which ages the insulator’s surface.
12. A change in the weather, such as the sun rising, reduces the wetting. As the insulator dries, the
discharge diminishes.
13. The insulator will...
... pressure. The gas is
ducted through the regenerator where the waste heat is transferred to the
incoming air. The gas is then discharged into the ambient air through the
exhaust stack. In effect, the ... reducing the performance gap between
these two types of gas turbines. The gas turbine to date in the combined
cycle mode is fast replacing the steam turbine as the base load provider of
electrical power ... throughout the world. This is even true in Europe and the
United States where the large steam turbines were the only type of base load
power in the fossil energy sector. The gas turbine from the 1960s...
... increase the
temperature and decrease the volume per the Brayton Cycle. The fuel is then added and the combustion
takes place in the combustor, which increases both the temperature and volume of the ... interrupting the circuit either to turn the load
on and off or to interrupt fault current. The first requirement is based on the full load current of the
load. Thesecond requirement is based on the maximum ... determined by the
way the generator is connected to thepower system. If the generator is connected directly to the power
system, a resistor or inductor connected between the neutral of the generator...
... introductory
network theory. He is currently the series editor for the Electrical EngineeringHandbook Series
published by CRC Press. In 1993 he was inducted into the Electrical Engineering Academy ... of Bus Admittance Matrix
The first step in developing the mathematical model describing thepower flow in the network is the
formulation of the bus admittance matrix. The bus admittance matrix ... to the study of power systems; in fact, power flow forms the core
of power system analysis. A power flow study is valuable for many reasons. For example, power flow
analyses play a key role in the...
... installed either inside the GIS enclosure or outside the GIS enclosure (Fig. 5.4).
The GIS conductor is the single turn primary for the CT. CTs inside the enclosure must be shielded from
the electric ... switches
are frequently used at the connection point of the GIS to the rest of theelectricpower network, not only
in case the connected line is energized, but also because the fast-acting ground switch ... arresters, and connections to the
rest of theelectricpower system) to match the electrical one-line diagram of the substation. A cross-
section view of a 242-kV GIS shows the construction and typical...
... regulator
is not the current that flows all the way from the regulator to the load center. The proper way to determine
the line impedance values is to run a power- flow program of the feeder without the regulator ... and the voltage unbalance at the load.
The line-to-ground voltages and line currents at the substation are:
Solve Eq. (6.85) for the load voltages:
The voltage unbalance at the load using the ... operating.
From the output of the program, the voltages at the regulator output and the load center are known.
Now the “equivalent” line impedance can be computed as:
(6.108)
In Eq. (6.108), the voltages...
... and
the cosine of the phase angle between the two. Thus, the torque is also proportional to thepower in the
metered circuit.
The device described so far is incomplete. In measuring a steady power ... of time is energy. In mathematical
terms, power integrated over time is energy. The basic electrical unit of energy is the watthour. The basic
unit of power is the watt. The watthour meter measures ... curve.
Hanson, Andrew ElectricPower Utilization”
The ElectricPowerEngineering Handbook
Ed. L.L. Grigsby
Boca Raton: CRC Press LLC, 2001
â 2001 CRC Press LLC
(N = 3), the meter must contain...
... known.
However, these currents are not known. Rather, something is known about the complex power and
voltage at each bus. The complex power injected into bus k of thepower system is defined by the
relationship ... approximating the partial derivatives of the real power equations with respect to the bus voltage
magnitudes as zero. Similarly, the partial derivatives of the reactive power equations with respect to the
bus ... reactive power are unknowns. The bus selected as the slack bus must have a
source of both real and reactive power, since the injected power at this bus must “swing” to take up the
“slack” in the solution....
... i.e., the impedance, at the relay location. The
impedance per mile is fairly constant so these relays respond to the distance between the relay location
and the fault location. As thepower systems ... prevent the fault. Its primary purpose is to detect
the fault and take the necessary action to minimize the damage to the equipment or to the system. The
most common parameters which reflect the presence ... towards the trip zone of the relay, and may even encroach on it, then leave again. The
unstable trajectory may pass through the entire trip zone of the relay. The relaying tasks are to detect,
and then...
... of the voltages induced by the release of the charges bound either by the cloud or by
the stepped leader are small compared with the voltages induced by the return stroke. Therefore, only
the ... d
ps
is the distance from the shield wire to the phase conductor. Z
11
is the surge impedance of the
phase conductor in the absence of the shield wire, Z
22
is the surge impedance of the shield ... voltage on the line.
If the lightning has subsequent strokes, then the subsequent components of the induced voltage will
be similar to one or the other of the four components discussed above.
The magnitudes...
... importantly, a function of the
transmission system reactance; the larger the reactance (for example, the longer or weaker the transmis-
sion circuits), the lower the maximum power.
2H
d
dt
TT
r
me
ω
=−
d
dt
d
dt
r
ω
δ
ω
=
2
0
2
2
0
2
2
Hd
dt
TT
me
ω
δ
=−
P
EE
X
P
e
B
T
=
′
=sin ... applied to the system given in Fig. 11.3. The only difference in the two cases is that the fault clearing
time has been increased for the unstable case. The arrows show the trace of the path followed ... into the vehicle as a result of the sudden push, and compare it with the energy
needed to climb the hill. In this method, there is no need to track the position of the vehicle as
it moves up the...
... foundation for their
calculations, the performance of the state estimator depends on the accuracy of the measured data as
well as the parameters of the network model. Fortunately, the use of all ... chosen so that the optimal solution was known a priori.
The dashed line in the load forecast represents the maximum output of the 10 units.
Before running the UC-GA, the user specifies the control ... minutes as the demand changes.
The losses in thepower system are a function of the generation pattern, and they are taken into account
by multiplying the generator incremental costs by the appropriate...
... next day, i.e., the 24 outputs are the forecasts of the hourly loads of the next
day. This ANN will be referred to as the “Regular Load Forecaster (RLF).” On the other hand, the second
ANN forecaster ... weather parameters forecasts for the coming day
ã Day type indices
The difference between the two ANNs is in their outputs. The first forecaster is trained to predict the
regular (base) load of the ... examples, called the training set, are applied to the ANN. The ANN learns by adjusting or
adapting the connection weights through comparing the output of the ANN to the expected output.
Once the ANN is...
... by knowing the value of the short-circuit current available at the secondary of the utility
transformer supplying power to the establishment (building) and the series impedance in the electrical
circuit ... switching event, there would be no power loss in the switch since either the current in the switch
is zero (switch open) or the voltage across the switch is zero (switch closed) and thepower loss ... across the load resistor is
rather large and, in typical power supplies, such ripples are unacceptable. The current through the load
is discontinuous and the current through the secondary of the...