500 KV GRID STATION CONTROL ROOM

Components of the Control Room Protection

Relays Auto Transformer Bank (ATB) Panel Bus Bar Panel Shunt Reactor Panel Rectifiers Fire Extinguisher Battery Room

Components of the Control Room Isolator

control panel Circuit breaker control panel Tape changer control panel Bergular alarms Lay out drawings

Protection Relays

RelayA

relay is a device that detects the fault and directs the circuit breaker to isolate the faulty part/equipment from the system.

Relay

Panel

Function of RelayA relay performs three functions. Sensing. Comparing. Tripping.

Sensing It

senses the fault. This is done by the relay to respond to the change if any, in the currents passing through it.

Comparing It

compares the current through it with the designed value of current. It responds only if the current through it is different from its designed current rating.

Tripping

If the current through it is different from its designed current rating, it sends information to the circuit breaker for tripping.

Qualities of a Good RelayIn order to perform its function successfully, a relay should have the following qualities. Selectivity. Speed. Sensitivity Reliability Simplicity. Economical.

Relays Application Ground

fault Phase fault Bus protection Transformer protection Generator & motor protection Auxiliary

Bucholz Relay Gas

operated relay Used only in oil immersed transformer Use to protect the internal faults of T/F

It is the simplest form of protection that can protect a transformer from all faults. It gives advance warning for any future fault.

Advantages of Bucholz relay

Disadvantages of Bucholz relay This device can be used only in oilcooled transformer.

This can detect fault only on the falling of oil level.

Auto Transformer Bank Panel

Auto Transformer

Auto Transformer This

is a transformer with only one winding instead of primary and secondary windings found on a simple power transformer

A/T

is the most important part of the grid station. It is used to step-up or step-down the voltage or power.

Advantages of A/T Single

double It is less expensive than simple Transformer of the same rating

winding is required instead of

ATB

Panel

The panel consists of Tap

Changer Phases Voltage Level Oil Temperature

Tap Changer It

is used to low or high the secondary voltage of A/T. It has different pins usually 27 pins. The voltage depends on the pin at which tap changer is set. In normal condition tap is set at between 10 to 14 .

Phases Voltage Level There

are three phases indicated by Red, Yellow and Blue cables. Each phase has its own current, voltage and temperature.

Oil TemperatureWe can monitor the temperature of oil. Fans are used to cool down the oil in order to decrease the temperature.

Rectifiers & Battery Room Relays

operate on D.C We need rechargeable batteries for the D.C To recharge batteries we need to convert A.C to D.C so we use Rectifier to do so All batteries are connected in parallel & each is of 2 V.

BATTERY ROOM

Shunt Reactor Panel

Shunt

Reactor

Shunt Reactor In

the transmission line where distance is very large the voltage can not remains constant in the entire line. This is called Front Effect. Shunt Reactor is used to maintain voltage level constant in the line

Shunt Reactor It

is usually plugged between two phases or between phase or neutral Long Transmission line which have less load, we need to compensate or absorb the reactive power due to line capacitances leading current

Fire Extinguisher

Fire Extinguisher

It

is an important part of grid station control room. It is used in accidental case of fire in control room

Circuit breaker

Circuit Breaker

It is piece of equipment which can Make

or break a circuit either manually or by remote control under normal conditions Break a circuit automatically under faulty conditions

Isolator

Isolator

Isolator

is a mechanical switch that is used to isolate transmission or other equipment in No-Load condition from energy sources Isolator is always placed before Circuit Breaker as Extra Protection

It

does not used to break the load current. Because there is no system to eliminate arc. It is basically used a no load switch

Opening of isolators

Difference b/w circuit breaker and Isolater Isolator

operates on no load condition because if we use isolator on loaded condition then arc will produce. We operate circuit breaker before isolator.

Bus Bar Panel

Bus Bar Panel

What is bus bar Bus

bar is a constant voltage supplier conductor.Bus bars are the nerve-centers of the power system where various circuits are connected together. These are the nodes of the electrical circuit. Under the normal power flow condition the sum of incoming currents is equal to the sum of outgoing currents.

This

is the simplest system, adopted to connect a number of generators, transformers etc, with the busbar. All these are connected through circuit breakers & isolators

Bus

bars and lines are important elements of electric power system require immediate attention of protection and inspection staff for safeguard against the possible faults

ADVANTAGES Simple

& cheap Needs little maintenance

DISADVANTAGES: Bus

bars cannot be cleaned or repaired without switching off the whole system If a fault occurs at bus bars, the whole of the arrangement has to be switched off.

Links and References 132

kv grid station muzaffargarh 500 kv grid station muzaffargarh www.wapda.gov.pk www.ntdc.com.pk www.mepco.com.pk Guide to electrical power system by Antony j.pansini

Thank you