internship report-KEl

Kohinoor Energy Limited

Muhammad Urshyan

University Of Engineering And Technology Lahore


Contents Introduction Safety First Voltage System Classifications

MV System HV System LV System

Other Systems Fuel System Booster System Cooling System

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Introduction Kohinoor energy Limited commonly known as KEL is a 124 MW power plant situated at Raiwand bypass. It is basically a thermal power Plant having eight 15 MW synchronous generators having diesel engines as their prime movers and a 6 MW generator having steam turbine as its prime mover whose steam is created by the exhaust gases of the engines . Fuel being used for running the generators and the steam turbine is High Fuel Oil(HFO). LFO is also being used for running the generators for servicing purposes. Electricity is being generated at 11kv and then stations transformers are used to step down the voltage level a part of the generated electricity to 404 volts and this Voltage is used to run the auxiliary system of the Plant itself . voltage level is increased to 132kv by using three main transformers and then its fed to the grid station. From grid station the electricity is transmitted to Wapda according to their requirement .


Fig.1. Kohinoor Power Plant

Safety First

“Safety First” is the basic Working principle of KEL where human life is prioritize over anything else. The plant as a whole along with its regulations is a sheer demonstration of that motto. Following are a few gestures that elaborate this principle.

Compulsory Safety outfit Sophisticated Fire extinguishing system Abundant sign boards

1. Safety Outfit A safety outfit equipped with the personal protected instruments is made compulsory for all the workers entering the plant area. This outfit includes the following entities:

Bolier Suit Safety Shoes Safety helmet Ear Muffs Safety Goggles Cotton gloves Walky Talky Set

All the entities are used according to the level of safety precautions needed at the place of work. i.e Places like workshop have low risks so a few entities can be skipped but at places like engine room require the usage of all of them. Fig.2 demonstrates the proper usage of the whole equipped outfit.

2. Fire Extinguishing System A very sophisticated fire alarm and fire extinguishing system has been installed in the plant. This system includes the following gestures:

Centralized Extinguisher Centralized fire extinguishing system has been installed in the whole plant and it is triggered by the fire sensors sensing the fire. Human Machine Interface


also shows the infected area red so that the evacuation of the workers can be carried with less trouble and losses can be minimized to as much as possible.


Fig.2. Proper Usage Of Personal Protective equipment

Fire Alarm System Fire alarm System is been installed in the plant too along with the alerting lights that start glowing whenever any incident occurs that can prove to be fatal , fire being one of them.

Pre-Mapped Exit Path An exit Path is been Mapped already to avoid any sort of misunderstandings while evacuating the plant in emergency cases. Green exit signs are displayed at every possible location to make it as easier as it can be to make the danger as less as possible for the working body of the plant. One of such signs is shown in the following Figure.


Fig.3. Hallway while Exiting the HV/LV workshop with exit sign above the door

Portable Extinguishers Portable extinguisher are also places abundantly at various spots of the plant in case the centralized system or the sensors get damaged and the worker needs tom indulge with the fire himself anyway.

Fig.4.Fire Extinguisher

3. Sign Boards Visual instructions have always been more influencing on the human beings rather than just audible ones . So throughout the plant sign boards bestowing the importance of human life and explaining the possible dangers that can be faced while any sort of negligence are places are different spots. A few vital purposes of these signs are given as following:

Precluding the engagement of workers with anything fatal to their lives Asking the workers put their safety above anything else Explaining the hazards workers can face while being


Voltage System Classification The plant has been classified into three categories considering the voltage level.

i. MV System (Medium Voltage System)ii. LV system (Low Voltage System)

iii. HV system ( High Voltage system)

Medium Voltage System

The System operating at the 11 KV is specified as the medium Voltage System. Majors parts to be studied at this level are given below:

Single line Diagram: Single line diagram shows the whole MV system on a single sheet or board to show the position of all the breakers along with the regulation of the MV system.

Generators: During this internship I understood the working of synchronous generators on practical basis. Took part in servicing a generator myself. And comprehended the protection system of the generator.

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Fig.5. generator engine assmebly


Generator Protection:

A reasonable number of relayed are used to protect the generator from every possible damage and faults. A few I observed there are given below:

Over current relay: Over current relays are used to prevent the damages when the current of the generator is increased from a specific peak value. These relays are basically used for the generating the signal to turn the generators off while such hazardous conditions occur. Normally used over current relays are electronic over current relays.

Fig.6 Electronic overcurrent relay

The way it works is that we set a reference current and the triggering time and then whenever the specific current limit is crossed for a specific time period the relay triggers a signal and the breaker turns the connection off. The diagram shown in the middle picture of figure.7 explains its functionality. How the CT’s provide the actual current in a downgraded scale and how the relay triggers the actions.

Earth fault relay: This relay is used for the same purpose but to trigger its action current overshoot current isn’t a parameter it turns the breaker off with the help of the PLC’s while the earthing Fault is detected somewhere.

Reverse power relay: Reverse power relay is used to track the amount of the reverse power in the circuit. In most such relays if the reverse power exceeds three to four percent of the generated power the relay turns the breaker on.

Over voltage relay: Over voltage relay work on the same principle as the over current relay and the but here we take voltage as a reference rather than current and PT’s are used instead of the CT’s.


Under Voltage relay: Under voltage relay does the same work as the over voltage relay but it does it in a different manner. Whenever the generated voltage in below a certain critical point it turns the generator off using the PLC control panel.

Differential current protection relay: This relay takes input from two points one from the input side and one from the output side usually and whenever the difference exceeds a defined limits it triggers a signal that can be used to perform whatever the action defined by the PLC. i.e turning the generator of or cutting the supply.

Excitation loss relay: This one is used to monitor the excitation loss in the generator ,whenever it exceeds a defined limit a signal is generated that can be used to perform the talk defined to it by the controller.

Diode monitor relay: This one gets triggered when any problem in the diodes used for the rectification purposes in the generator shows any problem or failure.

CT’s & PT’s:

CT’s and PT’s are used to take the step downed currents and voltages respectively for the following purposes:

Measurement: As meters can’t measure 11kv and 500 amperes directly we use CT’s and PT’s to step down the currents and voltages respectively and then according to the scale proper measurement can be done.

Protection: The step down voltage can be fed to the relays and the controllers for the comparisons that can decide whether all conditions all conditions of proper working are meeting or not.

Fig.7. CT and PT in the MV switchgear


SF6 Breaker: These breakers are used in MV system where SF6 is filled inside the breaker where contact is to be made or broken for the absorption of the spark.

Fig.9 SF6 breaker in MV switchgear

Whenever the contact has to be made the coil gets charged and the motor presses the spring and the connection is made and vice versa happens when the connection has to be broken. The six connectors in figure 9 are connected with six connection places shown in the breaker box in fig.8.

MV Switchgear: MV switchgear is basically what regulates the MV system. It consists of the breakers and meters and buss bars. Its purpose is to basically to feed the generated electricity to the buss bar for receiving and sending electricity to and from the transformers. .

MV Switchgear


MV Switchgear shown above has five units and three of them are for taking electricity from the generators and feed it to buss bar and the other two are sued to send it to the main and station transformers. Each unit from inside has shown in Fig.8 and Fig.9.CTs PT’s and SF6 breakers are used for the switching purposes.

Station Transformer: Station transformers are used to take the 11kv voltage and step down it to 404v for using electricity in auxiliary system. Electricity from this transformer goes to the LV switchgear. So, primary side of this transformer contributes to the medium voltage system.

Main Transformer: From MV switchgear the generator electricity goes to the main transformers at 11 KV where it is transformed to 132 KV and hence primary side of main transformer also corresponds to the medium voltage system.

Transformers Protections: A reasonable number of relayed are used to protect the transformer from every possible damage and faults. There are over current and over voltage relays just like the generator. The relays purely used for transformers are given below:

Buckle relays: These relays are used to detect the internal faults of the transformers. Mostly related to the fumes created inside.

Pressure relief relay: Pressure relief relay is used to detect any sort of sparks or other causes increasing the pressure of the oil inside that can cause the breaking of the bogy. What it does it opens the vacant paths for the passage of the pressurized fuel so that body can be saved from damage.

Oil temperature relay: This relay gets triggered whenever the oil temperature of the transformers increases a defined maximum temperature.

Winding temperature relay: This relay gets triggered when the winding temperature increase a specific limit and whatever the actions assigned to the tail are performed.

Brushless Excitation: Generators used in this plant have small generators along with them to excite the filed winding. These smaller generators induce current in the filed winding and hence there no physical contact is required for the excitation.

Low voltage system:

The system operating at 404 or less voltages in categorized as the low voltage system. The total auxiliary system of the plant falls into this category. The output to the stations transformers feed electricity to the lv switch gear and that’s the first link of the lv system.


LV Switchgear: Lv Switchgear has its input from the output of the station transformers. Then the auxiliary load is run by this supply.

Fig.11. LV switchgear

Tie Breaker: Tie breaker is a part of LV switchgear. It is used to shift the load of on buss bar one transformer on the other transformer.

Fig.12. Tie breaker


Fuse module/switch: Fuse module of switch are the fuses with the on/off switches. The purpose is to work safely over the fuses many of these can be seen in the LV switchgear.

Magnetic breaker: Magnetic breaker are used to break the circuit whenever needed. The plates are magnetized and the contact is made whenever the relay triggers the signal of breaking the circuit the magnetization vanishes and the circuit breaks.

Electronic over current relay: The way it works is that we set a reference current and the triggering time and then whenever the specific current limit is crossed for a specific time period the relay triggers a signal and the breaker turns the connection off. The diagram shown in the middle picture of figure.7 explains its functionality. How the CT’s provide the actual current in a downgraded scale and how the relay triggers the actions


Other System Classifications

Different systems are classified on the basis of their voltage level and functionalities a and during my stay at the plant I comprehended the following systems:

Fuel System Booster system Cooling System

Fuel System

The fuel System basically contains following parts

HFO storage tanks Storage tank fillers LFO storage tank Day tanks HFO Buffer tanks Transfer Pumps Purification Plant

1. HFO Storage Tanks There are four HFO storage tanks and they are used for the primary storage purpose. The fuel stored in it is the unpurified HFO.

Fig.12 HFO Storage tank


2. LFO Storage Tank LFO Storage tank is used for the Primary storage of the tank. There is only one LFO storage tank cause it is not needed in much quantity due to its rare using purposes .

3. Storage tank Fillers Fillers are used to fill HFO or LFO in their respective Storage tanks. The fuel is drawn from the oil tankers and filled in the storage tanks. The System is shown below.

Fig.13 Storage Tank Fillers

4. Transfer PumpsThere are two types of transfer pumps

I. HFO transfer Pump ( transfers HFO from storage tanks to the Buffer Tanks)

II. LFO transfer Pump (transfers LFO from storage Pump to the LFO day tank

The Basic purpose of these pumps is to take the fuel from the primary storage to the secondary storage where they can be processed or stored again to be fed to the engines.


Fig.14 Fuel Transfer Pump

5. HFO buffer Tanks HFO buffer tanks are the secondary storages of HFO. They are in the engine yard side of the plant. Transfer pump fed the fuel to buffer tanks and from buffer tanks the fuel is fed to the purification unit.

6. Purification Plant Purification Plant purifies the HFO before its fed to the engines. It takes fuel from the buffer tanks and its output fuel is stored into the day tanks.

7. Day tanks Day tanks are separately available for HFO and LFO. This is the last entity in the fuel system where purified fuel is stored and this is where from HFO or LFO is fed to the boosting system and then to generator.

Fig.15 HMI screenshot of fuel system

Booster System


Booster system is the system that pressurizes and heats the fuel before it enters the generator. HFO/LFO from their respective day tanks are fed to the booster system before they are fed to the generator. The input fuel is at room temperature and pressure but output fuel is at 7.7 bar and 94 Celsius.

Fig.16 HMI screenshot of Booster System

Cooling system

Cooling system is designed to keep the temperature of the generator at a specified level. There are six cooling towers for the generators and three for the turbine. The generator cooling system has three parts:

i. Cooling towerii. LT Fluid

iii. HT Fluid The way it works is that the cooling towers cools the LT fluid and that LT fluid is used to colleen the HT or High temperature fluid that is basically the fluid that runs in the generator to keep its temperature lower enough to operate properly. The normal temperature of working is 84 degree Celsius and there is not much temperature boosting while running of the so all this system has to do is lessen the temperature of the generators to like 5 to ten degrees. The HMI screenshot at next page explains it all along with the temperature levels of each side mentioned along.


Fig.17 HMI screenshot of generator cooling system

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