Transcript Power Distribution - kishorekaruppaswamy

POWER DISTRIBUTION
By
P.V. PAWAR
CPP
POWER
Apparent power : It is the product of r.m.s. value of voltage and r.m.s. value of
current. Its unit is VA, KVA, MVA
KVA - Apparent power
or Produced power = V X I
Power factor : Power factor is the ratio between the KW (actual power) and the
KVA drawn by an electrical load.
P.F. = KW
VI Cos phi
-------- = -------------- = Cos phi
KVA
VI
Causes of low factor
1) Induction motors.
2) Power transformers, welding transformers.
3) Industrial heating furnaces
4) Lighting loads through ballasts.
Effects of low factors :
1) Loss of electrical energy, I2Rt losses in transmission line.
2) Poor voltage regulation.
3) Poor use of electrical equipment ratings.
SINGLE PHASE / THREE PHASE
A single phase alternator has only one armature wdg. And hence they
produce a single alternating voltage and current. If the armature windings
are increased to 3, then it will produce 3 independent voltage waves. A
three phase alternator has three independent armature windings which
are 120 electrical degrees apart.
Two methods of interconnection –
1) Star connection or Y connection.
2) Delta connection or Mesh connection.
STAR / DELTA
Star Connection – Similar ends are connected
N is called star point or Neutral point.
A conductor can be connected to neutral point; it is called as neutral
conductor. Star connected system may be 3 phase 3 wire system or 3
phase 4 wire system as per the loading requirements.
Here, line current (IL) = phase current (Iph)
(contd)
Line voltage (VL) = Sq Rt 3 V ph
Power = Sq Rt 3 VL x IL x cos phi
STAR / DELTA
Delta connection :
Here dissimilar ends are connected, i.e. starting
end of one phase is connected to finishing end of other phase.
It is a 3 phase 3 wire system.
Here, VL = Vph
IL = Sq Rt 3 Iph
Power = Sq Rt 3 VL x IL x Cos phi
Hence in both the cases power = Sq Rt 3 VL x IL x Cos phi
Advantage of 3 phase system over single phase system : For the same
size a three phase a.c. machine has higher KVA capacity, hence is more
economical than single phase machine. Small loads like lighting loads,
fractional KW motors are single phase loads. Large motors, transformers,
machines are 3 phase loads.
Transformer
Transformer is a device/machine, that transfers electrical energy from one
electrical ckt. to another electrical circuit through the medium of magnetic
flux and without change in frequency. It decreases or increases the
voltage with corresponding decrease of currents keeping the power
same. Transformer is a static device, there is no moving part, so
efficiency is the highest amongst all machines and maintenance and
supervision is negligible.
It works on the principle of Electromagnetic Induction
Ns
Vs
Ip
Transformation ratio =----- = ----- = ----- = K
Np
Vp
Is
Transformer


Step up transformer
primary voltage.
Step down transformerprimary voltage.
Uses
of Transformer -
1) Backbone of ac transmission
2) CT/PT for metering/protection.
3) For isolating dc from AC
Secondary voltage is greater than
Secondary voltage is less than
POWER SYSTEM
For transmitting large power over large distances through
transmission lines voltage level is increased for less power losses.
All transmission and distribution system are 3-phase system.
Transmission lines and feeders are 3 phase 3 wire circuit while
distribution lines are 3 phase 4 wire circuit. Transmission lines are
generally overhead while distribution system can be overhead or
underground as per the locality.
Transmission Levels ( 66 KV, 132 KV, 220KV, 400KV, 765 KV)– (RMS)
Distribution Level – (400V, 3.3 KV, 6.6KV, 11KV, 33 KV) 50 hz (RMS)
SINGLE LINE DIAGRAM NC
VOLTAGE FLUCTUATION RECORDED AT 220KV
SYNCHRONISATION
When 2 power sources are to be connected in parallel
(together) , it is required to be synchronised.
To satisfy synchronisation condition
Both Voltages should be equal.
Frequency should be same.
Phase angle should be less than 15 degrees.
CPP operation with MSEB GRID
Power triangle
Power factor = Cos ¢ = KW / KVA
CPP OPERATION WITH MSEB GRID
While CPP is synchronized with MSEB GRID following 4 quadrant
shows possible conditions in which power flow can happen
Reactive power
import (KVAR)
Q2
Q1
Active power
export (KW)
Active power
import (KW)
Q3
Q4
Reactive power
export (KVAR)
PRESENT OPERATING CONDITIONS
For the purpose of billing, following two quadrants are applicable
since total KVA import is recorded in this region only.
Reactive power
import (KVAR)
Q1
Q4
Reactive power
export (KVAR)
Active power
import (KW)
MSEB BILL STRUCTURE
KWH
KVAH
RKVAH
(Lag)
KW(MD)
KVA(MD)
KWH = Total active power imported (Quantity on X axis)
KVAH =
[ KWH2 + (RKVAH Q1 + RKVAH Q4)2 ]
RKVAH lag = Total reactive power imported (Quantity on + Y
axis)
KVA (MD) = Average KVA supplied during thirty minutes period
of maximum use
MSEB BILL STRUCTURE
Billed Demand ( Which ever is higher of the following)
1) Actual KVA (MD) recorded between 06.00 to 22.00 for the month.
2) 50% of contract demand (17600 KVA is contract Demand)
3) 75% of maximum MD recorded in preceding 11 months.
PF penalty / Incentive :
PF < 0.9
0.9<=PF<=0.95
PF > 0.95
Penalty
No penalty / incentive
Incentive
Average Power Factor
Avg PF = KWH / KVAH
Assessed Power Factor
Assessed PF = cos [ tan-1(RKVAH (lag) / KWH) ]
WHY ASSESSED PF ?
Assessed PF = cos [ tan-1(RKVAH (lag) / KWH) ]
Avg PF = KWH / Total KVAH
Total KVAH
¢
Active power
import (KWH)
Reactive power export
(RKVAH lead)
Reactive power import
(RKVAH lag)
Q4
Q1
MSEB Tariff & Billing
• Fixed Part
(Demand charges in Rs/KVA)
This is called Demand charges. A consumer gets into contract
with MSEB for specified MVA demand. The Electricity board
should always have a provision for supplying the contracted
demand to the consumer. Therefore, MSEB charges a fixed
amount per MVA (called as billing demand).
The consumer has to pay this amount whether he utilises
power or not.
MSEB Tariff & Billing
• Variable Part
(Energy charges in Rs/kwh)
• This is called Energy charge. Depending upon the number
of units (KWH) consumed by the consumer, one has to pay
for it (Rs./KWH).
• Various levies & Duties are applicable to Fixed and Variable
Parts.
Constituents of MSEB bill
• Demand Charges : Charged on billing demand and
payable @ rate of Rs 3.5 lacs per MVA
•Additional supply charge leviable on 42% of energy
consumed at Rs 5.15/ unit
•Energy Charge : Charge for the number of units
consumed in a billing period ( month) and expressed in
Rs./KWH
Constituents of MSEB bill(Contd.)
• Fuel & Other Cost Adjustment Clause (FOCA): Energy
charges prescribed for the various classes of consumers
are based on an average cost of fuel which includes
expanses related to coal, furnace oil, L.D. oil or fuels
consumed in the Terminal or Gas Turbine Stations.
•Electricity Duty : Electricity Duty is collected in
accordance with the rates prescribed by Government from
time to time.
PF Penal Charges :
•
A penal charges is levied to the consumer
whenever the average power factor is less than 0.9,
at the rate of 1% on their monthly bill exclusive of fuel
adjustment charge, and electricity duty for each 1%
fall in the power factor below 0.90
BILL CALCULATIONS
Fixed part or Demand Charges :
 Contract Demand (CD) = 17,600 KVA or 17.6 MVA
 Minimum Demand (MD) = 50% of CD = 8.8 MVA
 Actual Demand (AD)
= as per the actual readings.
 Demand charges are calculated for the highest of the
values as per the following conditions.
 Condition 1 - AD between 6.00 hrs to 22.00 hrs.
 Condition 2 - 75% of the max. A.D. of last 11
months.
 Condition 3 - MD
 Present demand charge is Rs.350/KVA/Month.
Variable part or Energy charges
Shift
Time
A 22.00- 06.00
B
C
D
06.00- 09.00
12.00-18.00
09.00-12.00
18.00-22.00
Rate
(-85) Paise/unit
Normal rate Rs.2.15/unit
(+ 80) paise/unit
(+115) paise/unit
LOAD SHEDDING SCHEMES IN IPCL-MGCC
System Generated load shedding
• Hard wired load shedding
 This is as Frequency based load shedding.
 Entire 18 MW load selected, will be shedded at a
single stroke.
• ECS load shedding
HARD WIRED DEMAND BASED LOAD SHEDDING
Three blocks of load are shed one after the other if the
import exceeds the stipulated amount, by the operator
manually.
BLOCK-I :
BLOCK-II :
Township feeder 1 & 2
IWWTP .kv & PCC feeders
PP Extruder
LLDPE
Extruder
(1+2+3)
Ethyl BOG
Compressor(1+2)
LDPE Extruder
LDPE hyper compressor
LDPE Comb. Compressor
BLOCK-III :
LLDPE Recycle Compressor(1+2)
N2/O2 Demag. Compressor
W&C feeder 2
HARD WIRED DEMAND BASED LOAD SHEDDING
Different amounts of load are shed at different times of the
day according to our contract with the state grid.
a) For power import in A or B shift (0600 hrs to 2200
hrs)
Upto 9.0 MW (11.7 MVA)
No action
9-16 MW
BLOCK-I
16-23 MW
BLOCK-I&II
>23 MW
BLOCK-I,II&III
b) For power import in C shift ( 2200 hrs to 0600 hrs ,
next day)
Upto 14 MW
No action
14-21 MW
BLOCK-I
21-28 MW
BLOCK-I&II
>28 MW
BLOCK-I,II& III
POWER DISTRIBUTION.
• CPP 11 KV Bus is divided into 6 Bus sections namely
1A, 1B, 1C, 2A, 2B and 2C.
• Limiting Series Reactors, connecting buses 2B-2C
(Reactor 1) and buses 1B-1C (Reactor 2). These
series reactors have a rating of 11kV, 2000A.
• Each Bus section has a dedicated Power
Source.
POWER DISTRIBUTION
Bus 1A & 2A have MSEB source; whereas
theremaining4buses each have 1 Generator.
•
• 11KV feeders are provided to each Plant from this
CPP bus.
• The Plants receives power through 2 independent 11
KV feeders from CPP.
POWER DISTRIBUTION
• Each feeder is capable to carry 100% Load.
• One Plant feeder is connected to Bus 1A-1B-1C and
second to Bus 2C-2B-2A.
• There is at least 1 Plant feeder on MSEB source bus 1A or 2A.
POWER DISTRIBUTION
Each Plant has 2 incomers and a bus coupler
arrangement. Normally both incomers to plant are ON
with Bus coupler OFF.

 For transferring load from 1 incomer to other incomer
bus coupler is used.
 There is also Auto power transfer schemes, which
allows power to be transferred from unhealthy
incomer to healthy incomer.
Distribution Philosophy
NC receives power from MSEB through 2 grid
transformers.
 The generation and CPP to plant distribution network is
at 11KV.

 11 KV armoured cables are laid between CPP to
each plant mostly through underground tunnels or
laid underground.
 Each plant feeder is capable of carrying 100% plant
load.
 11KV power is received by plant to a 11KV
Siemens switch board, which consists of
vacuum circuit breakers.
VCB
Distribution Philosophy (Contd.)

3 nos. of 11KV motors, one each in LDPE, LLDPE and PP plants
are connected to respective plant 11KV board.
All these motors are direct-on-line starting motors.
 For all other HT motors, a separate 6.6 KV switch board is
installed.
6.6 KV switch board receives power from 11 KV switch board
in plant through 2 nos. of 11/6.6 KV transformer.
Each 11KV/6.6KV transformer can carry
100% load.
 For LT (415V) power supply requirement,
Power control centers (PCC) boards are
installed.
Distribution Philosophy (Contd.)
Each PCC receives power power from 11KV switch
board in plant through 2 nos. of 11KV/433V
transformer and each transformer can carry 100%
PCC load.
The primary of transformers are connected through
cables, whereas secondary of transformers may be a bus
duct or cable depending upon load.
All transformers have primary winding in Delta &
secondary in Star.

 All motors above 160 KW are HT motors.
 Motors rating of 55KW and above are Breaker
controlled motors.
Distribution Philosophy(Contd.)

Motors below 55KW are contactor controlled motors.
 Most of the motors below 55KW are fed
through Motor Control Centers( MCC ) which
receive power from PCC.
The internal plant load network connections are through
armoured cables laid on cable trays.
 Separate power &control cables are used.
 The largest size of LT cable is 300 sq. mm.
Power cables upto 300 sq. mm. are 3 core or 3 ½ core.
 Power cables greater than 300 sq.mm. single core
cables e.g. 1C * 400 sq.mm., 1C * 1000 sq.mm.
Distribution Philosophy(Contd.)
The emergency board may have a D.G. set connected to
it. All emergency loads like UPS, battery charger etc. are
connected to emergency boards. All emergency boards
are LT boards.
For lighting distribution, dedicated dry type transformers
are used, as the network is single phase.

Each lighting distribution boards(L.D.B) is provided
with ELCB.
 For street lighting 1st pole is connected to ‘R’ phase, 2nd
pole to ‘Y ‘ phase, 3rd to ‘B’ phase, 4th again to ‘R’ phase
and so on.
ELECTRICAL CONTROL SYSTEM (ECS)
•Supplied by M/S Westinghouse Process Control Division,
USA.
•Commissioned in 1989-90
•Electrical control system is a DCS used for MGCC
electrical network monitoring & control functions.
•16 redundant controller with I/Os at various substations
ELECTRICAL CONTROL SYSTEM (ECS)
•2 Operator & 1 Engineer station at CPP C/R.
•2 Historian at CPP C/R.
•Redundant MicroVAX computer at CPP C/R.
•Co-axial cable network as data highway.
•Repeater at GC and IOP sub station.
ECS APPLICATION PROGRAMS
Data acquisition from substations:
•Live data is updated maximum every second, converted to
engineering unit and limit checked.
•Electrical parameters monitored are: current, voltage, active
power, reactive power, breaker on/off, switch selection from
various substation, etc.
Alarm function.:
•Live data is checked against set limit,
incremental/decremental limit to generate an alarm.
ECS APPLICATION PROGRAMS
Log generation:
•Alarms & status change with date and time is logged
on a dedicated printer at one of the operator consoles to
facilitate analysis after any event.
Parameter monitoring/trending:
•Real time monitoring of parameters is available on
operator console in a trend format of 10 & 60 minutes
time span.
•Past trend of configured parameter is available for time
span of one second to 60 days.
ECS APPLICATION PROGRAMS
Tie line control:
•This application is used when CPP is operating in parallel
with MSEB.
•It controls power import/export from/to MSEB by sharing
the loads on the in plant running generators
Unit load control
VAR control of generator
Reactive power adjustment on generator is done through
a single screen having real time data of reactive power of
the entire system.
ECS APPLICATION PROGRAMS
Energy generation/consumption recording for all plants:
•Daily/Monthly energy accounting of plants &
equipments is done by resident algorithms.
Contingency analysis and load shedding:
Switch board bus transfer scheme:
EMERGENCY POWER
Emergency power system may also be defined as
Independent reserve source of electrical energy
On failure or outage of normal source (black out)
automatically provides reliable electric power
Black start of a gas turbine generator for restoration of
power.
Emergency D.G. set installed for
back-up supply to GT auxiliaries.
EMERGENCY POWER
AC
- UPS (Battery back up- 1 hour, CPP –30 min)
- DG Set
DC

- Battery charger (Battery back up)
Emergency lighting (AC/DC)
- Plant lighting (field/C.R./S.S.)
- Indicating lamps
- Protection supply
Battery Charger in CPP
110 V Battery Charger:
There is a dedicated battery charger for 110 V DC instrumentation
power supply with 2 battery backups and 2 Parallel redundant
Rectifiers.
125 V Battery Charger:
Each Gas turbine has a dedicated 125V DC Battery charger along with
battery back up for supplying control power to GTGs.
220 V Battery Charger:
There is a dedicated battery charger for 220 V DC power supply for
Electrical Switchgear control with 2 battery backups and 2 Parallel
redundant Rectifiers.
All the Battery Banks in CPP are of Nickel Cadmium type.
PROTECTION SYSTEM
for electrical faults
Generators have a comprehensive protection
system to cover all types of electrical faults.

 Grid islanding is done through
=>Under frequency, rate of fall and rise of
frequency
=>Under voltage
=> Directional over current and earth fault.
 All 220 KV and 11KV buses are protected by Bus
differential protection.
 All 11 KV cables to and from CPP are protected
by pilot wire cable differential protection.
PROTECTION SYSTEM
for electrical faults
All 5MVA and above rating transformers have
transformer differential protection.

 All breaker controlled motors have comprehensive
motor protection relay.
 All motors above 1MW rating have motor differential
protection.
 All feeders have over current and earth fault protection.
Power Distribution & Philosophy
THANK YOU
FROM CPP
I/C-1
I/C-2
ON
ON
OFF
ON
I/C-1
11KV BUS
I/C-2
OFF
ON
6.6KV BUS
ON
ON
M
OFF
415 V
PCC
MCC
M
AUTO TRANSFER SCHEME
I/C-1
ON
A
BUS-1
I/C-2
B
C
OFF
I/C-1
ON
BUS-2
ON
A
BUS-1
I/C-2
B
C
ON
BUS-2
To transfer total load to incomer-1 in case of loss of power to
incomer-2
Breaker-C will close only if all of following conditions are true:1. Breaker B is OFF.
2. No lockout relay operated for breaker A, B, C.
3. Breaker A is ON.
4. BUS-2 voltage below 10%.
5. BUS-1 voltage above 90%.
OFF
11kV BUS SINGLE LINE DIAGRAM