220kv grid wapda town lahore

220kV

Grid

Wapda Town

A Complete overview of Power Grid

Abdul Samad

Presented By

Substation

An Electrical Substation is a subsidiary station of an electricity Generation , Transmission And Distribution System where voltage is transformed high to low or reverse using transformer.

Examples of Substation:-

220kV/132kV substation



220kV Substation

It is divided into to(3) parts:-

I. Panel Section Control Panel Section

Relay and Protection Panel Section

II. Switch Yard 220kV Section

132kV section

33kV section

III. Battery Room

Panel Section

It has two sections

I. Control Panel Section It contain panels related to controlling of instruments.

E.g.:- feeder panel, X-mer panel, etc.

II. Relay And Protection Panel Section It contains panels related to relay systems and

protection systems. E.g.:- Relay panel, line protection panel, etc.

Switch Yard

It is the field where components used in controlling supply and measuring supply(incoming and outgoing) are placed

Some of these many components are:-

C.Bs

Isolators

C.Ts

P.Ts

L.As

X-mers, etc.

Equipment's used All Power-Grid Equipment's

MAIN EQUIPMENTS AT WAPDA TOWN SUBSTATION 220KV

Main equipment of Wapda town substation 220kV

* Ring Bus system :

I/C Supply

O/G feeder

Bus

CB

Tie CB

Main 1

Main 2

Feeder 1Feeder 2Feeder 2Tie CB

Feeder 1

* One and Breaker Half :

© OMICRON

Purpose of Circuit Breakers in Power Systems

> Minimize losses in closed position

> Open and close on command

>Open or close a circuit to connect

the power to/from the transmission

line

(O - break, C - make)

>Open a circuit for planned

maintenance (O - break)

>Open a circuit at system fault to

protect the system behind the

circuit breaker (O break, O-C

reclose, O-CO, auto-reclose)

>Isolate between poles, open

contacts and earth

x

Busbar

Disconnector

Circuit Breaker

PowerTransformer

x Circuit Breaker

Network

Equipment's used

Types of Conductors

What we have learnt …??

Conductors

Why We use Aluminum in place of Copper …??

Types of conductors used in 220kV substations are

AAC -> All Aluminum Conductors

AAAC -> All Aluminum Alloy Conductors

ACSR -> Aluminum Conductor Steel Reinforced

ACAR -> Aluminum Conductor Alloy Reinforced

Equipment's used

Types of Conductors


All Aluminum Conductors (AAC) &

All Aluminum-Alloy Conductor (AAAC)

For 36 kV transmission and above both aluminum conductor steel reinforced (ACSR) and all aluminum alloy conductor (AAAC) may be considered. Aluminum conductor alloy reinforced (ACAR) and all aluminum alloy conductors steel reinforced (AACSR) are less common than AAAC and all such conductors may be more expensive than ACSR

Equipment's used

Types of Conductors


Aluminum Conductor Steel Reinforced (ACSR)

Names of ASCRs

No. Of strands / No. Of steel Strands/diameter of strandsH.T Overhead Line

Sr. No. Names Size(mm)*

1. Rabbit 6/1/3.55

2. Panther 30/7/3.00

3. Zebra 54/7/3.00

4. Moose 54/7/3.53

Equipment's used

Types of Conductors


Aluminum Conductor Aluminum Alloy Reinforced (ACAR)

I. improved strength to weight ratio

II. better mechanical properties

III. improved electrical characteristics

IV. excellent resistance to corrosion

Equipment's used

Types of Conductors

Transformer

Transformer Colling Methods

ONAN

ONAF

OFAF

OFAN

Equipment's used

Types of Conductors

Transformer


ONAN Cooling Method

Equipment's used

Types of Conductors

Transformer


ONAF Cooling Method

Equipment's used

Types of Conductors

Transformer


OFAN Cooling Method

Equipment's used

Types of Conductors

Transformer


OFAF Cooling Method

Equipment's used

Types of Conductors

Transformer

Transformer Mechanical Protection

Buchholz Relay Working

Equipment's used

Types of Conductors

Transformer

Transformer Mechanical Protection

Buchholz Relay Position on Transformer

Equipment's used

Types of Conductors

Transformer

X-mersTesting

Transformer Testing

Earthing Test of Transformer

Equipment's used

Types of Conductors

Transformer

X-mersTesting

Transformer Testing

Earthing Test of Transformer Observations

(2-1) at 100A voltage drop was 0.5V at test set

(2-3) at 100A voltage drop was 0.39V because of test lead







Equipment's used

Types of Conductors

Transformer

X-mersTesting

Transformer Testing

Transformer Turn Ratio Test

HV Side LV Side

Equipment's used

Types of Conductors

Transformer

X-mersTesting

Transformer Testing

Step 1.

First, the tap changer of transformer is kept in lowest position and LV

terminals are kept open. In this test we check that the voltages at the LV

side according to the turn ratio of rated LV side and HV side are according

to the rated value. We use Megger for the supply of 400V during the testing

of TTR.

Step 2.

For testing purpose we open both the LV and HV sides. We supply 400V

using Megger Device. And at the side we received 34.28V.

Star-Delta Turns Ratio Delta-Star Turns Ratio

Equipment's used

Types of Conductors

Transformer

X-mersTesting

Transformer Testing

Megger Insulation Resistance Test

1. HV to LV

Step 1.

Open HV & LV sides of the transformer.

Step 2.

Short the terminals of both sides of Star & Delta Winding

Equipment's used

Types of Conductors

Transformer

X-mersTesting

Transformer Testing

Step 3.

We supplied voltages at the HV side of +5KV DC and -5KV DC at LV side.

Step 4.

By measuring the voltage drop we calculate the resistance of core and

windings.

Step 5.

And then we compare the calculated with the commissioned report.

Equipment's used

Types of Conductors

Transformer

X-mersTesting

Transformer Testing

Step 1.


Step 2.

Short the terminals of both sides of Star

& Delta Winding.

Step 3.

We supplied voltages at the HV side of +12KV DC and GND at LV side.

Step 4.

By measuring the voltage drop we calculate the resistance between windings turns of HV side

Step 5.


2. HV to GND

Equipment's used

Types of Conductors

Transformer

X-mersTesting

Transformer Testing

3. LV to GND

Step 1.


Step 2.

Short the terminals of both sides of

Star & Delta Winding.

Step 3.

We supplied voltages at the LV side of

+12KV DC and GND at HV side.

Step 4.

By measuring the voltage drop we calculate the resistance between

windings turns of LV side.

Step 5.


Equipment's used

Types of Conductors

Transformer

X-mersTesting

Transformer Testing

Winding Resistance Test

Step 1.

We open the HV & LV windings of the

transformer.

Step 2.

Current is injected into winding using

current injection set.

Step 3.Supply should be DC 100A because of measuring resistance and if we use

AC then it consists of capacitive reactance, inductive reactance and the

total combination of impedance of the above. So that’s why we don’t use

AC and hence we use DC to avoid the above problems to find the winding

resistance.

Step 4.For LV side testing we test between red & Neutral, Yellow & Neutral, and

Blue & Neutral for LV side or star connected side.

Equipment's used

Types of Conductors

Transformer

X-mersTesting

Transformer Testing

Step 5.

For HV side or Delta connected side we measure resistance between

phases (red,blue), (red,yellow) and (yellow,blue).

Purpose

Calculate the I2 R losses in conductor.

Calculation of winding temperature at the end of temperature test

cycle.

It provides a base line which tells us about the possible damage in the

field.

Equipment's used

Types of Conductors

Transformer

X-mersTesting

Transformer Testing

Temperature Rise Test

Step 1.

First the LV winding of the transformer is short circuited.

Step 2.

Then one thermometer is placed

in a pocket in transformer top

cover. Other two thermometers

are placed at the inlet and outlet

of the cooler bank respectively.

Step 3.

The voltage of such value is applied to the HV winding that power

input is equal to no load losses plus load losses corrected to a

reference temperature of 75°C.

Equipment's used

Types of Conductors

Transformer

X-mersTesting

Transformer Testing

Step 5.

During the test, hourly readings of top oil temperature are taken from

the thermometer already placed in the pocket of top cover.

Hourly readings of the thermometers placed at inlet and outlet of the cooler bank are also noted to calculate the mean temperature of the oil. And finally we read the temperature at steady state and stop the testing method.

Step 6

Equipment's used

Types of Conductors

Transformer

X-mersTesting

Transformer Testing

Current Transformer Test

The voltage shall be applied between:

1. Primary to secondary plus ground

(covered during switchgear test).

2. Secondary to primary plus ground.

3. Secondary core to core.

The above diagram shows that how a CT measure the current practically

or numerically.

Equipment's used

Types of Conductors

Transformer

X-mersTesting

Transformer Testing

Capacitance and dissipation factor test

It is a low AC voltage maintenance test similar to power factor test to

measure capacitance and dissipation of transformer insulation system.

Acceptance testing stage to establish base line reading for future.

Step 1.

Isolate the equipment, apply working grounds to all incoming and outgoing

cables and disconnect all incoming and outgoing cables from the

transformer bushing terminals. Disconnected cables should have sufficient

clearance from the switchgear terminals greater that the phase spacing

distance.

Equipment's used

Types of Conductors

Transformer

X-mersTesting

Transformer Testing

Step 2.

Isolate the neutral bushing connection if applicable from the transformer

grounding bar.

Step 3.

Short-circuit all high voltage bushing terminals together.

Step 4.

Short-circuit all low voltage bushing terminals and the neutral bushing

terminal together.

Step 5.

Connect the capacitance and dissipation factor test set. Refer to Figure , on

next slide.

Equipment's used

Types of Conductors

Transformer

X-mersTesting

Transformer Testing

Step 6.

Record the capacitance and dissipation factor values once the null meter is

balance for both phasing position. Record values for the five test-variable

selector switch position.

Equipment's used

Types of Conductors

Transformer

X-mersTesting

Transformer Testing

Purpose

Condition of Bushing and overall insulation

of transformer can be investigated.

Aging and decomposition of insulation increase the losses are

determined through this test.

Equipment's used

Types of Conductors

Transformer

X-mers Testing

Monitoring & Control

panel

Monitoring & Control Panels

Monitoring Panel Equipment

• Ampere meters• Voltmeters• Kilowatt meters• KVAR meters• Power factor meters• Energy Meters

In the monitoring and control room, there are two kinds of panels;


Equipment's used

Types of Conductors

Transformer

X-mers Testing

Bus Bar, Safety & Battery Room


Monitoring Panel Equipment

• Alarms• Indications

Breaker open

BuchhlozRelay

SF6 low pressure

Relay active


panel

Equipment's used

Types of Conductors

Transformer

X-mers Testing



• Push buttons and switches• Power supply• Relays

Control Panel Equipment

RectifierBattery charger

+Batteries

To control panel(dc)

AC

Backup supply forcontrol panel (dc)


panel

Equipment's used

Types of Conductors

Transformer

X-mers Testing


Transformer

DY - 132/11kV, 20/26MVA

Rated current HV = 114 A

Rated current LV = 1366 A

If 10% of rated voltage (suppose), rated current flows in

secondary when short circuited.

13.2kV ==== 1366 A

13.2kV * 10 === 1366 A * 10 V1 V2Transformer

Equipment's used

Types of Conductors

Transformer

X-mersTesting

Bus Bar & Safety

Bus Bar Scheme

Different bus bar arrangements:

Some of the switching schemes are bus bar arrangements employed in the substations are listed below:

Single Bus-bar arrangement Double Main Bus-bar scheme Main and Transfer bus-bar scheme One and half breaker scheme Ring Main arrangement scheme

Monitoring & control

Equipment's used

Types of Conductors

Transformer

X-mersTesting

Bus Bar & Safety

Bus Bar Scheme

Double Main Bus-bar scheme

Advantages:I. Any circuit can be taken out of circuit for

maintenanceII. Flexibility in connecting the feeder circuit

to either of the bus barsDisadvantages:I. Most expensiveII. Loose circuits connected to bus bar when

fault occurs on the bus bar


Equipment's used

Types of Conductors

Transformer

X-mersTesting

Bus Bar & Safety

Fire Extinguishers Types


Equipment's used

Types of Conductors

Transformer

X-mersTesting

BusBar, Safety & Battery Room

Battery Room

What is the purpose of battery room ..??

It is the Heart of Grid Provides backup Protection devices run on this


Equipment's used

Types of Conductors

Transformer

X-mers Testing


Testing of Batteries


Visual Inspection Test

Equipment's used

Types of Conductors

Transformer

X-mers Testing


Testing of Batteries


Voltage Test

220kv grid wapda town lahore

Engineering

Transcript of 220kv grid wapda town lahore