INCENTIVE
FOR
TRANSMISSION EFFICIENCY
-
T. UMESH , SEE, RETD. KPTCL
-
-
&
N. RAGHUPRAKASH , EE, RA, KPTCL
IN THIS SESSION

Brief introduction to Transmission System

Efficiency Parameters in Transmission Activity

Transmission Loss & its calculation

System Availability & its calculation

Incentive Calculation by KERC.
INTRODUCTION TO TRANSMISSION NETWORK

Transmission Voltages in Karnataka

Transmission System Elements

AC/ DC lines

Power Transformers ( ICTs)

STATIC VAR Compensators

BUS REACTORS
TRANSMISSION SYSTEM EFFICIENCY
Measured in terms of
 Transmission
loss
 Transmission
system availability
TRANSMISSION LOSS
MYT Regulation , clause 3.4 deals with treatment of
losses.
 In the tariff order KERC stipulates the normative
transmission losses to be achieved by KPTCL during
MYT period.
 If the loss is less, then incentive is allowed. This gain
is to be shared in the ratio of 70: 30 between STU and
the users of transmission system.
 SLDC works out the Transmission loss
month on
month based on the input to the transmission system
and the quantum of energy supplied to ESCOMs at the
Inter Face points. This information is furnished to
KERC based on which the Order for sharing of loss /
gain on account of Transmission loss is issued.

INCENTIVE FOR TRANSMISSION EFFICIENCY


KERC vide its MYT Regulations -2006 Order
dated 31.05.2006 has stipulated that KPTCL
shall maintain a minimum of 98% availability for
recovery of full transmission charges.
Recovery of fixed charges below the level of target
availability shall be on pro-rata basis. At zero
availability, no transmission charges shall be
payable.
PROCEDURE FOR CALCULATION OF
AVAILABILITY
Availability shall be calculated and declared
separately for each voltage level.
 The transmission elements shall be grouped
into following categories.
 a) AC transmission lines: Each circuit of AC
transmission line shall be considered as one
element.
 b) Inter-Connecting Transformers: Each 3ph
transformer or bank of three Sph transformer
shall form one element.

PROCEDURE FOR CALCULATION OF
AVAILABILITY
c) Static VAR Compensator: SVC along with SVC
transformer if any shall form one element.
 d) Switched Bus Reactor: Each switched Bus
Reactor shall be considered as one element.
 Weightage factor for each category of
transmission elements shall be as under:
 a) For each circuit of AC line- Surge Impedance
loading (SIL) multiplied by Circuit Km. ( SIL
rating for various voltage level and conductor
configuration shall be as per the procedure
adopted for power system analysis)

PROCEDURE FOR CALCULATION OF
TRANSMISSION SYSTEM AVAILABILITY (TSA)
b) For each ICT- The rated MVA capacity
 c) For SVC- The rated MVAR capacity
 d) For switched Bus Reactor: The rated MVAR
capacity.


The availability for each category of transmission
elements shall be calculated based on the
weightage factor, total hours under consideration
and non-available hours for each element of that
category.
The transmission elements under outage due to
following reasons not attributable to KPTCL
shall be deemed to be available:
 1) Shut down of transmission elements availed by
other agencies for maintenance or construction of
their transmission system.
 2) Manual tripping of the line due to over voltage
and manual tripping of elements as per the
directions of the RLDC/SLDC.

Outage time of elements due to acts of God and
force majeure events beyond control of KPTCL
shall be excluded.
 Outage time caused by grid disturbance not
attributable to KPTCL shall also be excluded. Eg.
Faults in substations or bays owned by other
agencies causing outage of KPTCL elements.
 However, if the elements are not restored on
receipt of directions from SLDC while
normalizing the system following a grid
disturbance within reasonable time, then the
element will be considered not available for
whole period of outage and outage time shall
be attributable to KPTCL.

The % availability is calculated for each
transmission element as follows:
 1st calculate Availability index= Total time under
consideration-Outage hours due to unscheduled
interruptions/Total time under consideration.
 Next
calculate
availability=
Availability
index*Weightage factor
 % availability= availability/weightage factor
 Then, % availability of category of elements=
Sum of availability of all elements/sum of
weightage factor of all elements.
 Then, % System Availability is calculated as the
average of all category availabilities.

FORMULA FOR CALCULATION
% TSA = o*AV₀ + p*AVp + q*AVq + r*AVr X 100
o+p+q+r
Where ,
AV = Availability
o = No. of AC lines
p = No. of ICTs
q = Capacitor Bank
r = Bus Reactors
Zone: Bangalore
Element: AC lines
Sl.
No.
Name of the line
Voltage
Conductor Ckt.kM
kV
A
1 Nelamangala - Peenya I
2
3
4
5
220 Drake
17
UnTotal time of
Weightage
Scheduled Availability Availability
%
SIL
considerationfactor
Interrupti
Index
(Avi)
Availability
hours
ons- hours
B
132
C=A*B
2244
D
E
8760
F=(D-E)/D
4.87
0.999
G=C*F
H=G/C*100
2242.752
99.944%
290
Total
1305556.1
1304626.78
Sl.No.
Zone
No. of AC
lines
Wf
Availability
No. of
ICT's
Wf
Availability
No. of
SVAR's
Wf
Availability
%TSA of
Zones
1 Bagalkote
311
697757.44
695026.05
471
9702.5
9684.27
22
462
460.71
99.73
2 Bangalore
290 1305556.08
1304626.78
499
15753.9
15745.99
31
688.28
688.28
99.94
3 Gulbarga
173
738584.22
734879.11
311
6021.5
6005.16
19
456
455.37
99.65
4 Hassan
198
931824.81
928881.66
268
5836.2
5834.83
16
371
356.16
99.72
5 Mysore
134
176175.12
176082.58
233
3842.6
3841.02
27
430
430
99.96
6 Tumkur
98
286133.19
285761.46
342
6079.7
6076.21
0
0
0
99.93
1204 4136030.86
4125257.64
2124
47236.4
47187.48
115
2407.28
2390.52
99.82
KPTCL TOTAL
KPTCL TOTAL
AVO
1204 0.997395276
AVP
2124 0.998964358
AVQ
115 0.993037785
%TSA= 99.82177037
INCENTIVE
KPTCL shall be entitled to incentive on achieving
annual availability beyond the target availability
of 98% as per the following formula.
 Incentive=
ATC*
(TSA
achieved-Target
availability)/Target availability
 No
incentive shall be payable above the
availability of 99.75%.
 50% of the incentive shall be shared by the long
time customers in the ratio of their average
allotted transmission capacity for the year.

SURGE IMPEDANCE LOADING
Surge Impedance Loading (SIL) in MW’s of a long
transmission line is defined as ratio of (kVRE)²/SI
where VRE is the receiving end voltage in KV and
SI is surge impedance of the line.
 SIL is typically the limit of the maximum power
that can be transmitted through the line at the
voltage level considered.
 SIL can be increased by reducing the SI of the
line.

SIL VALUES AS PER KEGC 2005
Typical values of SIL are as follows:
 a) 400 kV lines – Quad conductor- 1051 MW
 b) 400 kV lines – Twin conductor-515 MW
 c) 220kV lines – Single conductor-132 MW
 d) 110kV lines – SC – 50 MW
 e) 66kV lines – SC – 35 MW

SURGE IMPEDANCE
SI is defined as the √(L/C), where L and C are
Inductance and Capacitance of the line.
 SI can be reduced by bundling.
 Bundling is the use of two or more conductors per
phase, which reduces L and increases C.
 Hence
twin/quad conductors are used in
400/765kV lines.

Transmission lines produce reactive power due to their
natural capacitance.
 Mvar produced = ½ CV²
 Transmission lines also utilize reactive power to
maintain their magnetic fields.
 Mvar used = ½ LI²
 SIL is the loading of the line when Mvar produced =
Mvar used
 i.e., when ½ LI² = ½ CV²
 Which gives V/I = sqare root of L/C, which is nothing
but the SI of the line.

THANK YOU