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12003 FEE > Power Systems > Flashcards

Power Systems Flashcards

(75 cards)

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1
Q

What is solar power?

A

Energy from the thermo-nuclear reactions of the sun.

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2
Q

What is photovoltaics?

A

The generation of voltage/ current when a photovoltaic cell is exposed to light

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3
Q

How are solar modules composed?

A

LOOK AT THE DIAGRAM IN NOTES

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4
Q

What is open circuit voltage used for?

A

Voc is used to measure the voltage output of a solar module

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5
Q

What is short circuit current used for?

A

Measures the maximum current that flows out of a solar module

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6
Q

What is the max power point?

A

Pmax = Imax x Vmax

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7
Q

What effect does sun irradiance have on panel current and voltage?

A

No (minimal) effect on voltage
as irradiance decreases current decreases

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8
Q

What effect does temperature have on the efficiency of a solar panel?

A

As the temperature increases, the efficiency decreases

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9
Q

What happens I and V of solar panels in series?

A

Add the V and I remain constant

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10
Q

What happens to the I and V for solar panels in parallel?

A

V remains constant and add the Is

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11
Q

What happens to parallel panels with different voltages?

A

total V would be the same as the lowest
sum the currents

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12
Q

What is a stand-alone system?

A

A system that operates independently from the grid (see diagram)

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13
Q

What is a hybrid system?>

A

That uses personal solar panels and the grid for energy supply

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14
Q

What is a grid system?

A

Use of large solar panel farms for energy supply

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15
Q

What are the steps for system creation?

A

( Just look in the notes this isn’t flash card possible)

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16
Q

What is wind power?

A

The conversion of kinetic energy from the wind into electrical work

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17
Q

What is a HAWT?

A

Horizontal axis wind turbine where the rotating axis is parallel to wind stream

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18
Q

+ves of HAWT?

A

High aerodynamic efficiency
More power produced per unit
Low cost per unit of output

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19
Q

What does the pitch system do?

A

Makes sure the pitch (angle of the blade) is optimal for efficient energy transfer

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20
Q

What does the yaw do?

A

Turns the turbine towards the wind

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21
Q

What is an upwind HAWT?

A

The wind hits the blades first
(diagram may help)

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22
Q

What are the -ves of an upwind HAWT?

A

higher bending loads
higher rotor mass
more blade damage
requires a yaw

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23
Q

What is a downwind HAWT?

A

Wind doesn’t hit the blades first.

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24
Q

What are the benefits of a downwind HAWT?

A

It doesn’t need a yaw as the wind automatically blows it in the direction it needs to face.

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25
What is stalling?
Changing the angle of the blades to limit the output
26
What is furling?
The blades are completely turning out of the wind to stop them
27
What is the purpose of both furling and stalling?
Used @ high wind speeds to stop damage to a turbine (probs safety too)
28
What is a VAWT? (see diagram)
Vertical Axis Wind Turbine, where the rotating axis is perpendicular to the group
29
What are the benefits of the VAWT?
It accepts all wind directions It doesn't need a yaw Simpler Cheaper per individual unit
30
What is the Bertz Limit?
The maximum efficiency of a turbine @59.3%
31
What does windpower depend on?
Area Air density Wind speeds Pitch angle (control factor 1) Tip speed (control factor 2)
32
How does height affect wind turbine output?
As you get higher the wind speed increases which would increase power output however As you get higher the air density decreases exponentially, which reduces power output
33
What makes finding a tip speed ratio difficult?
It must be varied to maximise efficiency as only 1 ratio is most efficient for 1 wind speed
34
What is capacity factor?
CF = (energy generated in a year) / (max possible energy generated)
35
What is a good approximation of the capacity factor?
0.0087 * v (avg) - Power rating / (diamter)^2
36
How much energy is in 1 ton of oil ( 1 toe)
42GjJ
37
What are the thermodynamic laws?
Conservation of energy Entropy of interacting systems never reach 0 (whatever this means)
38
How does a conventional thermal station work?
Use of fossil fuels to evapourate water in order to turn a turbine
39
How does a nuclear power station work?
Use of a nuclear fission to evapourate a water to turn a turbine
40
What are the 3 types of nuclear power plants? (their names describe what they do)
Pressurised water reactor Pressurised heavy water reactors Boiling water reactors
41
What is a combined cycle gas turbine?
A facility that generates electricity by using both a gas turbine and a steam turbine to make the most of the heat produced during the process.
42
How does a combined cycle gas turbine work?
It uses the wasted heat to boil more water which is then passed through a turbine
43
What is HEP?
The use of water in a dam to turn a turbine
44
What are the +ves of HEP?
It is renewable It has a predictable output It lasts long without needing replacement
45
What are the -ves of HEP?
Geography (needs a dam and needs to be transported) Causes river damage
46
What is pumped storage HEP?
Pumping water into a higher place (so it has potential energy) and releasing it to turn a turbine when energy demands require it
47
What are the -ves of pumper storage HEP?
It causes a net energy loss
48
What is carbon capture and storage?
Capturing carbon dioxide and storing it in geological formations
49
What is the +ve of Carbon capture and storage?
It reduces green house gasses emitted into the atmosphere
50
What is the -ve of Carbon capture and storage?
Depends of geography Requires more fuel
51
What is combined heat and power?
A conventional thermal station that recycles waste steam for it to be used for heating. (combines thermal energy for heating and electrical energy)
52
What is wave power?
The use of waves to turn a turbine
53
+ves of wave power?
Low environmental impact
54
-ves of wave power?
hard to reach 50hz requirements breaks in storms
55
What is tidal energy?
The use of gpe from the moon to move tides through a generator
56
What is the load factor?
The actual amount of energy (KWh) delivered by a system in a period of time.
57
What is domestic load?
Energy consumed by households
58
How do domestic loads vary?
Less than commercial and more than industrial @ 30 - 60% usage
59
What is commercial load?
The energy consumed by commercial businesses for things like lighting and heating.
60
How does commercial load vary?
The most out of the 3. 20-80%
61
What is industrial load?
Energy consumed by small, medium and large called industries?
62
How does industrial load vary?
90%+ all the time
63
What are some examples of resistive loads?
Lights, heaters, toasters
64
Examples of inductive loads?
Washing machines Fridges Air con
65
Look at load duration curves
YESS SIRR
66
What are tariffs?
The rate at which energy is supplied to consumers
67
What is the role of tariffs?
Return on investment for suppliers Fair to consumers Simple
68
What are the 4 types of tariffs we need to know?
Simple, flat rate, two-part and three-part.
69
What is the Price elasticity of demand?
%Δdemand/ %Δprice
70
What is perfect elasticity?
Infinite change in demand at any given price
71
What is elastic demand?
When a %change in price leads to a greater %change in demand
72
What is unitary demand?
When the %change in price and %demand are the same
73
What is inelastic demand?
When a %change in price leads to a smaller %change in demand
74
What is perfect inelastic demand?
When a change in price has no effect on demand
75

12003 FEE (5 decks)

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