Substation theory and practice
An electrical substation is a subsidiary station of an electricity generation, transmission and distribution system where voltage is transformed from high to low or the reverse using transformers. Electric power may flow through several substations between generating plant and consumer, and may be changed in voltage in several steps.
A substation that has a step-up transformer increases the voltage while decreasing the current, while a step-down transformer decreases the voltage while increasing the current for domestic and commercial distribution. The word substation comes from the days before the distribution system became a grid.
The first substations were connected to only one power station where the generator was housed, and were subsidiaries of that power station.
Equipment in substation
Substations generally have switching, protection and control equipment and one or more transformers. In a large substation, circuit breakers are used to interrupt any short-circuits or overload currents that may occur on the network. Smaller distribution stations may use recloser circuit breakers or fuses for protection of distribution circuits. Substations do not usually have generators, although a power plant may have a substation nearby.
Other devices such as power factor correction capacitors and voltage regulators may also be located at a substation.
High-rise buildings may have several indoor substations. Indoor substations are usually found in urban areas to reduce the noise from the transformers, for reasons of appearance, or to protect switchgear from extreme climate or pollution conditions.
Where a substation has a metallic fence, it must be properly grounded (UK: earthed) to protect people from high voltages that may occur during a fault in the network.
Earth faults at a substation can cause a ground potential rise. Currents flowing in the Earth’s surface during a fault can cause metal objects to have a significantly different voltage than the ground under a person’s feet; this touch potential presents a hazard of electrocution.
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Can we consider one VCB with metering and protection system for one transformer?
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I am looking for literature related with Substation Ground Grid Connectors for Below Grade Applications
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hello i am experiencing a 95% stator earth fault on my generator protection .relay its an REG670 please assit
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please i want to get the calculation design on a capacitores in electrical substation and and how can we calculate the size of capacitance to instull in electrical power system
How to calculate the substation fault level and what are the inputs are required
Can we consider parallel runs in determining short circuit rating of feeder?
Example: 33KV incoming feeder has to be designed for 33KV, 31.5KA, 1sec rated Panel to feed 20MW, feeder length is about 2000 m to be laid in RCC Trenches.
2Runs 33KV, 300 Sqmm, AL Cond., XLPE Cable is recommended to cater 20MW, 350A & fault current of 31.5KA, 1 Sec.
1Run of 300 Sqmm, AL Cond., XLPE Cable can carry 310A in duct @ 30 deg C and about 28KA for 1 sec as per manf. catalog.
Considering De-rating Factors for temperature & grouping etc. actual capacity 237Amps/ Run
So 2 runs cater 474 Amps i.e. more than sufficient to cater required 350A.
As 2 Runs are considered it is supposed to cater 31.5KA, 1sec considering current sharing in parallel runs.
Kindly give your advice on the above.
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