Power and Electrical Services Flashcards
Week 2 Lecture (14 cards)
What is AC, what is DC, and what is the main difference?
AC changes direction periodically, while DC flows in a single, constant direction
Alternating current (AC)
* There is a frequency, e.g. cycles per second
* Average values for voltage and currents
* Such as for large rotating power generators
* Most of the electric power network
* Careful demand
and supply balance
at 0.02 seconds
intervals (50Hz)
Direct current (DC)
* There is no frequency
* Such as batteries, computers, iPads,
mobile phones
* Solar panels
How does energy typically get to consumers, list out each phase of the process?
- Generation Station
–> generating step-up transformer - Transmission Lines
–> Transmission customer - Substation step down transformer
- Substransmission customer
- Primary customer
- Secondary customer
Generation, transmission, distribution, retailers
Who are the energy generators in Australia?
- AGL
- Energy Australia
- Origin Energy
- Stanwell, Tarong
What companies transmit the electrical power?
- Powerlink
- TransGrid
- ElectraNet
Who are the energy distributors?
- Energex
- Ergon
- Ausgrid
- CitiPower
Who are the energy retailers?
- AGL, Energy Australia, Origin
Energy - Ergon Energy (regional QLD)
- Alinta
What is the cumulative efficiency from coal to electricity to the home?
28%
What is the difference between traditional and modern power grids?
Traditional Grid - one-way energy flow
Modern - has two-way energy flow, because of locally generated renewable energy such as rooftop solar photovoltaic systems
What are the common frequencies and voltages in Australia
Allowable voltage at the customer’s point of supply
230V + 10%, 6%(nominal)
230V + 6.1%-2.2% (preferred)
Frequency
50Hz
What is the difference between power and energy, and their unit?
Power (how fast we are using energy) , Units REAL POWER: Watts (W), kilo-watts (kW) or apparent power: VA, kilo-VA (kVA)
Energy, Watt-hour (Wh) or VAh
Basics of energy tariffs
- charged for our connection and usage
- Or for what generate and export to the grid
Fixed charges:
- e.g. $ per day in a billing cycle
- for metering, administration, billing etc.
Variable charges:
- Based on energy (kWh, or kVAh)
For electricity usage, generation and losses
- Bases on peak power demand (kW or kVA)
For building and maintaining the network.
How does electricity get to us, a basic run-down?
- Power grid
- Substations
- Main switchboards
- Distribution Boards
- Lights and power outlets
How does a solar PV system work?
- Solar panels generate direct current (DC) from sunlight
It is a photovoltaic process: - “photo” means light
- “voltaic” means voltage/electricity
Solar panels’ output -> Inverter (power electronics) -> Form of grid electricity
- Inverter change direct current (DC) into alternating current (AC)
- Then feed the renewable energy switchboards for homes and businesses
How do we decide on the placement of solar panels?
Available area
Orientation, geography
Local surroundings
User behaviour
Technical limitations
