Chapter 4 Flashcards
direct current
an electric current flowing in one direction only
The first commercial electric power transmission (developed by Thomas Edison in the late nineteenth century) used direct current. DC had a great limitation – namely, that power plants could only send DC electricity about a mile before the electricity began to lose power
Because of the significant advantages of alternating current over direct current in transforming and transmission, electric power distribution is nearly all alternating current today
alternating current
an electric current that reverses its direction many times a second at regular intervals, typically used in power supplies.
AC is the form in which electric power is delivered to businesses and residences.
One advantage that AC has over DC is that it can easily be “stepped up” or “stepped down” with a transformer. In other words, a transformer can take a low-voltage current and make it a high-voltage current, and vice versa.
transformers
allow for conversion of low-voltage electricity into higher voltage electricity. reduces losses incurred in transmission.
transformers that step transmission voltages (in the tens or hundreds of thousands of volts range) down to distribution voltages (typically less than 10,000 volts).
network effect
Metcalfe’s Law
occurs when the value of a service provided increases exponentially with a number of participants on the network
proportionate costs to provide service to ea. person falls as more people are added to the network
this creates a powerful incentives for utilities to scale quickly and eliminate competition
Public Utility Holding Company Act (PUHCA)
1934/1935. PUHCA + Federal Power Act –> changed how utility holding companies operate. utilities had to be more closely governed, provide transparency, obtain regulatory approval
this legislation created a REGULATORY BARGAIN among utilities, ratepayers, and state regulators to help rationalize the provision of electricity. Utilities could carve out monopoly territories, but would be subject to rate regulation
Busbar
grid typically begins here.
the point that a generator connects to the grid (typically at an electric substation). functions as a conductor of the electricity generated into the grid
a good place to measure the Q of energy AND cost/P. location where all of the costs of Generation are accounted for – and no T&D costs have yet been incurred.
Transmission
requires converting electricity to higher voltages to decrease line losses.
most electricity needs to be transformed into lower voltages (step-down transformers) to enter into distribution grid
Distribution
at the distribution grid, power can be delivered to medium-sized customers or stepped down further to go to commercial or residential facilities
US standardized output 120V
Frequency
US - 60Hz
Eur - 50 Hz
both voltage and frequency of delivered power in transmission systems matter
Load
electricity in motion which is nearly instantaneously linked from the source/generator to the final user (Customer Load)
Voltage
x
Base load
portion of the load that’s always being demanded, there’s always some amount of electricity required
Peak load
the load that occurs when the system is operating near its max. not simply the peak of a given day, but a load that is requiring the delivery electricity near max amount for any time during the year.
the system must therefore have some reserves to meet highest needs, even if they only occur for a few days/year
Load duration curve
shows the spread of loads across hours
takes the load levels for each of the 8,760 hours/year and sorts them so that the hours w/ the highest load comes first and then in declining order
ADD GRAPH
Capacity factor
net capacity factor/load factor
ratio of its actual output over a period of time TO its potential output if it were possible for it to operate at full nameplate capacity indefinitely
= (total amount produced in time unit) / (amount of energy produced at full capacity)
