Group No. : 02 Course No. : EEE 306 Experiment No. : 05 Experiment Name :

STUDY OF BUET POWER PLANT AND SUB-STATION Name : MD. Abul Kalam Azad Student NO. : 0406015 Level 3 ; Term 1 Dept. : EEE Date Of Performance : 19-06-07 & 26-06-07 Date Of Submission : 03-07-07

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Objective :

The objective of the study is to get an exposure to a realistic small power plant and LT substation. Introduction :

BUET has a small (2 MW) power plant and its own distribution network and sub-stations to meet its electrical energy demand. The power plant is located at west palasy campus of BUET and uses gas as its primary source of energy. The power plant supplies electricity to three sub-stations through under ground cable. The sub-stations distributes to each building, pump, street lighting at 230v.

The peak demand of BUET campus at present is 1750kw. The power plant supplies electrical energy to BUET campus from early morning till mid-night and from mid-night till early morning electrical energy is taken from the DESA distribution system. The changeover is done automatically by Automatic Transfer Switches (ATS) located at each sub-station. Experiment description: Our visit is divided into two parts:

Power plant visit Sub-stations visit

Power plant visit:

The BUET power plant consists of two 1 MW (actually their rating is 1030 KW each) gas engine generators and very soon another 2 MW generator will be incorporated in the system. The plant is fully automated with control and monitoring panels. Power plant has main two parts:

Generation unit Control unit

Generation unit :

This part consist mainly generator engine and its mountings and fittings as well as accessories also. A 16 cylinder gas engine is coupled with a synchronous generator and a flywheel also. This engine starts with the help of a DC motor. Therere two generator operating parallel to supply electricity. The cooling system of machine is done with the help of water circulation and water is cooled by radiator placed on roof. Insides air temperature is controlled by adjustable fans. Lubricant oil is also used for smooth running of machine.

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Some data of generation unit : Manufacturer : Caterpillar. Capacity : 1030 KW (each). Number of cylinder : 16 Number of radiator fan : 10 (for each generator) Number of ventilation fan : 4 Fuel : Natural gas. Speed of machine : 1500 rpm. DC battery voltage : 24 v. Generating voltage : 440v(L-L). Frequency : around 50 Hz. Power factor (pf) : always keep above 0.8 Temperature inside cylinder : 643 degree Celsius. Temperature of coolant (water) : 98 degree Celsius. Rated pressure of supply gas : 11 psi. Observed pressure of supply gas : 7 psi.

We operate our generator between 40% to 80% of rated KW for efficiency of our power plant. Protection measure of generating unit :

Fire extinguisher. Air muffler. Radiator fan. Cooling water. Lubricating oil.

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Flow diagram of generation unit :

Control unit :

Control unit consist two control panel for generator , six feeder , radiator fan controller and other control system. These are described here : Generator control panel 1 : From this panel we can control as well as protect generator 1 Observation result : Power generation : 736 KW , 436 KVAR. Frequency : 50.53 Hz. Power factor (pf) : 0.86 Voltage (3-) : 400.3v , 403.6v , 403.7v. Generator control panel 2 : From this panel we can control as well as protect generator 2

Gas from gas line

Control panel

Cooler + Radiator

Filter Engine + Generator

Feeders

Exhaust DC motor

Filtrate Air

Lubricant oil

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Observation result : Power generation : 750 KW , 335 KVAR. Frequency : 50.6 Hz. Power factor (pf) : 0.91 Voltage (3-) : 400.3v , 404v , 403v. Current (3-) : 20A , 110A , 121A. Feeder :

From this section electric energy is supplied to external load. There are six feeder which are described here : Feeder 1 : From this feeder electric energy is sent to Nzrul Islam Hall (New). Observation data : Supplied power : 126 KW Frequency : 50.2 Hz Power factor (pf) : 0.86 Three phase voltage : 401.2v , 406.9v , 409.2v Single phase voltage : 233.5v , 233v , 231.2v Line current : 209A , 197A , 214A Feeder 2 : From this feeder electric energy is sent to Main sub-station no. 1 : Observation data : Supplied power : 232 KW , 289 KVAR. Frequency : 52 Hz Power factor (pf) : 0.95 Three phase voltage : 403.4v , 403.2v , 400.3v Line current : 289A , 239A , 319A Feeder 3 : From this feeder electric energy is sent to M. A. Rashid Hall. Observation data : Supplied power : 291 KW , 133 KVAR Frequency : 50.2 Hz Power factor (pf) : 0.94 Three phase voltage : 400.3v , 401v , 401.2v Single phase voltage : 232.1v , 234.2v , 232v Line current : 453A , 451A , 460A

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Feeder 4 : From this feeder electric energy is sent to Nazrul Islam Hall (Old). Observation data : Supplied power : 82 KW Frequency : 50.5 Hz Power factor (pf) : 0.98 Three phase voltage : 400v , 403.8v , 407.8v Single phase voltage : 231.2v , 233v , 233.2v Line current : 120A , 109A , 111A Feeder 5 : From this feeder electric energy is sent to Main sub-station no. 2 : Observation data : Supplied power : 485 KW , 238 KVAR Frequency : 50.5 Hz Power factor (pf) : 0.89 Three phase voltage : 397.8v , 400.4v , 404.8v Single phase voltage : 231.3v , 232.3v , 230.2v Line current : 860A , 714A , 717A Feeder 6 : From this feeder electric energy is sent to EME Building : We can take data because it has no display on its body.

There is also a section from which we can control radiator fan. It has 20 block. Each block is used to control each fan of radiator. Protection :

Another important part of control unit is protection. Protection devices are set in generator control panel. Protections keep generator safe from damages. Emergency protection is taken against are :

Emergency stop Fail to start Over speed Low lubricating oil pressure High coolant temperature EMCP diagnostic fault Over voltage Under voltage Under frequency

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Reverse power trip

If one of this fault is occurred then corresponding light and alarm be on and then we take steps to our valuable generator.

Description of these protective device : Emergency stop :

This alarm is on when any problem occurs in engine or generator. Then we stop the generator as quickly as possible. Fail to start :

This gives signal when generator fail to start. Over speed :

When generator run with over speed then this signal turns on. Low lubricating oil pressure :

If lubricating oil pressure come down then minimum pressure rating provided by manufacture then this alert turned on. High coolant temperature :

When temperature of coolant water rise above the maximum rated temperature given by manufacture then this alert light become on. Over voltage :

If generated voltage rise above maximum acceptable voltage then this warning is on. Under voltage :

If generated voltage goes down minimum acceptable voltage then this warning is on. Under frequency :

If generator operated less than minimum acceptable frequency then the alarm on. Reverse power :

When a generator becomes consuming power rather delivering then reverse power trip separate the generator from line to keep generator run as a motor.

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Block diagram of complete power plant :

Gas engine

Feeder - 1

Feeder - 3

Generator - 2

Gas from gas line

Control panel - 2

Control panel - 1

Gas engine Gas from gas line

Generator - 1

Feeder - 2

Lubricant oil

Radiator Exhaust

Feeder - 4

Feeder - 5

Feeder - 6

Distribution Network through sub-stations

Control panel of radiator for generator - 2

Control panel of radiator for generator - 1

DC battery (24 v)

DC battery Exhaust Radiator (24 v)

Lubricant oil

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Sub-stations visit :

In sub-stations visit we visit M. A. Rashid Hall sub-station and Main sub-station. Our sub-station transformer step down voltage from 11 KV to 415 V coming from DESA line. All BUET sub-substations consists of mainly the following components :

Step down transformer Incoming and outgoing feeders HT and LT panel Circuit breaker Automatic Transfer Switch (ATS) Relays Metering instruments (CT , PT , meter)

We can divide this part of visit in two parts :

M. A. Rashid Hall sub-station Main sub-station

M. A. Rashid Hall sub-station : Automatic Transfer Switch (ATS) : Reading : Current : 480 A Voltage : 400 V (L-L) ; 215 V (L-N) Frequency : 51.2 Hz Transformer : Capacity : 750 KVA 11 KV / 415 V Y Feeders : It has eight feeder :

Titumir Hall S. W. Hall Sher E Bangla Hall M. A. Rashid Hall Azad pump(40 HP) and Azad quarter IPCDR & IAT Bhabon Ladies hostel Old pump house (60 HP)

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Main Sub-station : It has three panel. Panel 1 : ATS 1: Current : 300A , 300A , 280A Voltage : 390V Frequency : 50 Hz Feeders : This panel has eight feeders :

Machine shop Arch. Building O. A. bhabon(west) A/C bhabon(east) EME lift Civil lift Store / Mechanical Auto shop

Panel 2 : ATS 2 : Current : 620A , 580A , 620A Voltage : 385 V Frequency : 50.7 Hz Feeders : This panel has eleven feeders :

Civil Bhabon Central library Auditorium A/C plant Auditorium Engg. Office URP bhabon IICT

Feeder 2 reading : Current : 600 A Voltage : 385 V

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Panel 3 : ATS 3 : Current : 440 A Voltage : 395 V Frequency : 51 Hz Feeders : This panel has five feeders :

Library EME / EE EME / ME Arch. Bhabon Controller bhabon

Arch. Building feeder reading : Current : R 38.7 A ; Y - 12.6 A ; B 9.1 A Controller Building feeder reading : Current : R 62.3 A ; Y 73.6 A ; B 122.4 A EME feeder reading : Current : R 221.6 A ; Y 119 A ; B 153.2 A Automatic Transfer Switch (ATS) :

It is a SPDT type switch which switches line from DESA to BUET or from BUET to DESA. This switching is operated by microcontroller based timer relay. Power factor improvement (PFI) plant :

Its a capacitor bank used to improvement of load and connect parallel to ATS. Switch-gear protection :

It protect device from damages during fault. Meter :

Its a HT meter provided by DESA for measuring electrical energy used by BUET.

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Transformer : Manufacturer : Energy Pack (class A) Type : 3 ; - Y Normal operating temperature : 50 55 degree Celsius Rated KVA : 500 KVA Frequency : 50 Hz HT side : Voltage : 11 KV Current : 26.24 A LT side : Voltage : 415 V Current : 695.6 A In general block diagram of sub-station :

Ring main unit (RMU)

DESA HT meter

Switch Gear DESA line

3 Transformer ( - Y)

ATS PFI

Feeders Load

BUET line

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