Viva

Wagdy Ahmed Moustafa Mansour
Electrical and Electronics Engineering Department
Universiti Teknologi PETRONAS
Supervisor: Ir Mohd Faris Bin Abdullah
Final Year Project Viva
“Technical-Economic Analysis in the Application of
Series Capacitor Compensation for Distribution
Networks”

Project
Background
Problem
Statement
Objectives
Literature
Review
Methodology
Results and
Discussion
Recommendations
Conclusion
Q & A
PRESENTATION FLOW:

OUTLINE:
Project
Background
Problem
Statement
Objectives
Literature
Review
Methodology
Results and
Discussion
Recommendations
Conclusion
Q & A

PROJECT BACKGROUND:
• The use of Series capacitors is widely common for compensating losses
on current carrying lines.
• How it works ?
• Series Compensation is achieved by reducing the reactance value on the
line between the supply bus and load.
• An injected value of the capacitor negative reactance will eliminate the
huge amount of the line positive reactance and as a result the line
impedance is reduced in total.
• Main Application: Electric Grid Lines Compensation
Fig.1: Concept of Series Compensation

• A network consists of various
electrical equipment for
delivering electricity from
suppliers to consumers[10].
Transmission Lines:
• High-voltage current carrying
cables that carry power from
distant sources to demand centers.
• Long Distance (80 Km and Above)
• High Rated Voltage Levels (33,
132, 275, 500 KV)
Distribution Networks:
• Distribution networks that connect
individual customers.
• Shorter Distance (Not more than
50 Km)
• Lower Rated Voltage Levels (33,
22, 11, 6.6 KV and 400/230 V)
 ELECTRIC GRID:
Fig.2: Typical Power System

• The concept is to add a voltage in series with the lines to maintain a fixed
voltage value at the load side despite any load variations. And so, any voltage
drops in the line can be compensated [1].
• By doing that, the voltage profile will be greatly improved and at the same time,
the line losses are reduced [2].
• An important factor - the degree of compensation (𝑲) – which is the ratio of
line reactance to be compensated in order to enhance the overall performance of
the line.
• K is chosen to be in the range of 25 % to 75 % to avoid overcompensation
which increases the risk of ferroresonance.
Fig.3: Series Capacitor Compensated Distribution Lines

• When K = 75 % , the line will be electrically shorter by 50 % and 75 % respectively
which means that only a part of the line will be affecting the transmission process.
Uncompensated line
Compensated line K = 75 %
Compensated line K = 50 %

• A typical series capacitor unit is not just a capacitor in series with the
line.
• For proper functioning, series compensation requires control,
protection and monitoring to enable it to perform as an integrated part
of a power system.
• Also, since the series capacitor is working at the same voltage level as
the rest of the system, it needs to be fully insulated to ground.
 SERIES CAPACITOR COMPENSATION UNIT:

• Capacitor Bank
Consists of capacitor units connected
in series and parallel to obtain the
required total Mvar ratings
(Compensation Percentage).
• Metal Oxide Varistor
Protect series capacitor against over-
voltages caused by faults in the
surrounding network.
• Damping Circuit
Limit and damp the discharge current
caused by spark gap operation or
closing the bypass breaker.
• Bypass Breaker
Allow the series capacitor to be
bypassed In cases of internal faults
and reinsert the faulted line after fault
is cleared[8].
Fig.5: ABB MiniCap Internal Structure
(Single Line)
 INTERNAL STRUCTURE:

OUTLINE:
Project
Background
Problem
Statement
Objectives
Literature
Review
Methodology
Results
Discussion
Recommendations
Conclusion
Q & A

1. Series Capacitor Compensation is not widely used in distribution
systems due to unfamiliarity in the design, operation, negative
effects.
2. There are no recent studies analyzing the technical effects along with
the economic effects of applying series capacitor compensation
method in distribution networks with respect to:
• Reduction in Reactive Power input from the grid system.
• Enhancement in voltage profile
• The ability to increase Power Transfer Capability of the system.
PROBLEM STATEMENT:

 To Compare two proposed alternatives for increasing Power Transfer
Capability in a typical distribution system. The two alternatives are;
Series Capacitor Compensation and New line construction.
 To analyze possible reduction in reactive power input to the grid.
 To Determine the optimum location on the distribution network for
applying series capacitor compensation.
OBJECTIVES:

LITERATURE REVIEW:
Voltage Profile and Power Transfer Capability:
• In distribution networks, voltage fluctuations are caused by switching
of heavy loads, starting of large motors and transformer energizing[11].
• This results in an instantaneous voltage drop which usually lasts for a
few seconds until the motor reaches the operating speed[3].
• This may trigger the operation of voltage sensitive controls (Under
Voltage), leading to extensive disconnection of loads and thus
adversely affecting consumers and company Revenues.[11]

• In addition, the power transfer capability of a line is a fixed value
and is identified by the design standards and line ratings.
• Increasing the PTC might be crucial in times of economical growth.
• Alternatives can be proposed such as uprating the feeder voltage,
constructing a parallel feeder, and constructing a new substation [3].
• When considering any of the alternatives, big investments should be
made to cover the expenses needed.
• That’s why an accurate cost optimization should be made to confirm
if the alternative is economically justified or not.

 Series Compensation as an Alternative:
• A case study performed by ABB Sweden was
analyzed to evaluate some of the proposed
alternatives. In the study, An existing 1300
MW transmission system using two parallel
500 kV lines is to be upgraded to a 2000 MW
system.
• The options are to series compensate the two
existing lines or build a third parallel line[4].
• The Cost Analysis showed that the total investment for compensating the two
existing lines will be approximately 10 percent of building a third, parallel line.
• The study proved series capacitor compensation as a proper, cost effective and
environmentally acceptable solution to help enhance the voltage profile and PTC.

Economic Evaluation of Alternatives:
Investments in the energy sector are usually managed by the government because of the
high criticality on the country’s economy.
It reflects not only investment costs but also other items –operational costs,
deprecations, reducing of costs of supply interruptions and the time value of the money
[11].
In the analysis, there are two main terms to be introduced which are present worth, and
annual worth [12]. The present worth is the value of an expected income flow
determined as of the date of the project’s appraisal and it can be calculated as in
Equation 2.0.
P = AW(P/A, i %, n) Equation (2.0)
As for the annual worth, it is defined as the yearly cost of owning and operating an asset
over its entire lifespan and can be calculated by Equation 2.1.
A = PW(A/P, i %, n) Equation (2.0)
Where;
i is the rate of return
n is the lifespan

As a public sector project, there are significant differences in its characteristics
comparing to private sector alternatives.
• Size of investment will demand large initial investments.
• Project’s life estimates is important as public projects often have long lifespans.
• Low interest rate.
• Publicly owned projects have costs that are paid mostly by the government unit.
• A main aim of benefiting the citizens.

Alternative Selection using Incremental Benefit-Cost Ratio Analysis:
• The incremental benefit-cost analysis is used to choose the best option from a list
of mutually exclusive alternatives [15] .
• Mutually exclusive alternatives can be defined as the business proposals of a
certain project where only one of these proposals can be selected.
• Applicable for all types of investment projects with a main aim of improving the
current business schemes.
• The examples of this improvement may vary from a simple replacement in a
certain project to the full construction of new plants or factories.

METHODOLOGY:
Project's first activity (Proof of Concept)
Project’s second activity (Location Based Compensation)
Project's third activity (Distribution Network Series Capacitor
Compensation)
Analysis and evaluation of the data obtained.
Project’s fourth activity (Economic evaluation of proposed alternatives)

Project 1st activity:
To prove the technical concept of series capacitor compensation in
enhancing transmission efficiency
Generator Load
Transmission Line
Bus 1 Bus 2 Step-down
TransformerStep –up
Transformer
• Different degrees of compensation (K)
• Capacitor Unit is placed at the midpoint between bus 1 and 2
• Measurements:
 Voltage profile at the receiving end of the line (load side)
 The reactive power input to the system
 The power transfer capability

Generator Load
Transmission LineBus 1 Bus 2 Step-down
Transformer
L/2 L/2
K = 25 %
K = 75 %K = 40 % K = 60 %

Project 2nd activity:
Generator Load
Transmission Line
Bus 1 Bus 2 Step-down
Transformer
To determine the location where the capacitor unit should be positioned to
give its highest performance
• Different degrees of compensation (K)
• Different locations (D) - the total length of the line is divided into twelve (12)
sections.
• Measurements:
 Voltage profile at the receiving end of the line (load side)
 The reactive power input to the system
 The power transfer capability

K = 25 %
K = 75 %K = 40 % K = 60 %

Project 3rd activity:
To investigate application of series compensation on an electrical
distribution network

L = 10 km L = 30 km L = 50 km
K = 75 %K = 40 %
• The compensation is applied for the line with the highest reactance.
• Two degrees of compensation K = 40 %, K = 75 %
• Three different locations at 𝐷 = 1/2, 𝐷 = 3/4, 𝐷 = 2/3 of the total line’s
length.
• Three different line lengths are assumed; 10 km, 30 km and 50 km.

Project 4th activity:
To economically justify the most suitable alternative for an electrical
distribution network
• Justify the two alternatives technically regarding their abilities in
enhancing transmission efficiency.
• The incremental benefit cost ratio is implemented to compare the overall
cost of applying either of the alternatives.
• Determine the equivalent total costs for both alternatives.
• Order the alternatives by equivalent total cost: first smaller, then larger.
Calculate the incremental cost (∆C) for the larger-cost alternative. This is
the denominator in ∆B/C.
• Calculate the equivalent total benefits.
• Calculate the incremental benefits (∆B) for the larger-cost alternative.
• Calculate the ∆B/ ∆C ratio.
• Use the selection guideline to select the lower-cost alternative if ∆B/ ∆C <
1.0

Project 2nd activity:
Vr
• An increase in voltage magnitude by increasing K
• An increase in voltage magnitude by reducing the distance between the load
and the capacitor unit D
• Voltage magnitude must not exceed +,- 5 % of its nominal value

Ps
• A significant increase in
PTC by increasing K
• An increase in PTC by
reducing the distance
between the load and
the capacitor unit D
• Positive impact
• The limit depends on
line rating and its
ability to transfer active
power

Qs
• A decrease in reactive power input to the network by increasing K
• An increase in reactive power input to the network by reducing the distance between
the load and the capacitor unit D
• A suitable location must be chosen to get the least Qs without affecting other
transmission parameters

• A compensation degree of K = 75 % which has been proven as the most suitable for
enhancing the transmission efficiency.
• The series capacitor unit’s location is estimated at a distance of 𝐷 = 2/3 or 𝐷 =
3/4 of the total length of the line.
• For 250 km line, the most suitable location for implementing series compensation
will be at 200 km or 225 km from the line’s sending end.

Project 3rd activity:
0.92 0.94 0.96 0.98 1 1.02 1.04
No
Compensation
40%
Compensation
75%
Compensation
Voltage (pu)
VR at L = 10 km
VR at D =
3/4
VR at D =
2/3
VR at D =
1/2
0.93
0.94
0.95
0.96
0.97
0.98
0.99
1
1.01
1.02
1.03
No Compensation 40% Compensation 75% Compensation
Voltage(pu)
VR at L = 30 km
VR at D = 1/2
VR at D = 2/3
VR at D = 3/4

0.9
0.95
1
1.05
1.1
No
Compensation
40%
Compensation
75%
Compensation
Voltage (pu)
VR at L = 50 km
VR at D = 3/4
VR at D = 2/3
VR at D = 1/2
• An overall enhancement in the receiving end voltage profile with
K = 75 %
• No significant impact on the voltage profile when changing the
capacitor unit’s location along the line.

0
0.5
1
1.5
2
2.5
3
3.5
No Compensation
40%
Compensation 75%
Compensation
Power(pu)
PS at L = 10 km
PS at D = 3/4
PS at D = 2/3
PS at D = 1/2
0
0.5 1
1.5
2
2.5
No Compensation
40% Compensation
75% Compensation
Power (pu)
PS at L = 30 km
PS at D = 1/2
PS at D = 2/3
PS at D = 3/4

0
0.2
0.4
0.6
0.8
1
1.2
1.4
1.6
1.8
No
Compensation 40%
Compensation 75%
Compensation
Power(pu)
PS at L = 50 km
PS at D = 3/4
PS at D = 2/3
PS at D = 1/2
• A significant increase in the power transfer capability along the line with
K = 75 %
• No significant impact on the PTC when changing the capacitor unit’s
location along the line.

Project 4th activity:
Case Study:
 Line rating: 33 kv
 Total length: 30 km
 Power transfer capability: 117 MVA
 Line reactance: 0.7 + j2.901 MΩ / per km
Proposed Alternatives to increase PTC:
 Alternative 1: Compensating the existing line with capacitor unit (series
capacitor compensation)
 Alternative 2: Construction of a new line.

Alternative Comparison (Technical):
0.92
0.94
0.96
0.98
1
1.02
75%
Compensation
New Line
No
Compensation
Voltage (pu)
Alternatives Comparison (VR)
VR
0
0.5
1
1.5
2
2.5
75% Compensation New Line No Compensation
Power(pu)
Alternatives Comparison (PTC)
75% Compensation
New Line
No Compensation

• An overall enhancement in the receiving end voltage profile with K = 75 %
• A significant increase in the power transfer capability by 93 % (1.09 pu) along the
line with K = 75 % (Alternative 1) comparing to 18 % (0.22 pu) (Alternative 2).
• Alternative 1 has been technically justified.
Alternative Comparison (Economic):
Price
per
Mwh MW
Hourly
Benefits Daily Benefits
Annual
Benefits
Initial
investment
Annual Cost
(O&M)
Alternative 1 50 109 5450 130800 47742000 480000 48000
Alternative 2 50 22 1100 26400 9636000 5400000 540000
PW1C = initial cost 1 + pw of
(O&M1) 641880 1121880
PW1B = present worth of annually
estimated benefits 3105617.1
PW2C = initial cost 2 + pw of
(O&M2) 7221150 12621150
PW2B = present worth of annually
estimated benefits 626821.8
ΔC 11499270
ΔB 2478795.3
ΔB/ΔC 0.215 As ΔB/ΔC < 1 ∴ Alternative 1 is justified

 Benefits: an increase in PTC by 1.09 pu (119
MVA) at base power of 100 MVA.
 Estimated annual value of benefits = 47742000
USD per year at MW/h price of 50 USD.
 Capacitor reactance = Total line reactance * 0.75
= 87 * 0.75 = 65.25 MVAR
 Suggested capacitor unit: ABB MiniCap (12
MVAR per unit)
 N = 65.25 / 12 = 6 units
 Unit price = 70000 USD
 Shipping and installation cost = 10000 USD
 Total initial cost = 70000 * 6 + 10000 * 6 =
480000 USD
 Maintenance and operation per year = 10 % of
total cost = 48000 USD per year
Alternative 1:
ABB MiniCap – 3 Phase Series
Capacitor Unit

Alternative 2:
 Benefits: an increase in PTC by 0.22 pu (22 MVA) at base power of 100 MVA.
 Estimated annual value of benefits = 9636000 USD per year at MW/h price of 50
USD.
 Construction cost per km = 180000 USD
 Total initial cost = 180000 * 30 = 5400000 USD
 Maintenance and operation per year = 540000 USD per year

 PROJECT KEY MILESTONE:
No. Item/Week 1 2 3 4 5 6 7 8 9 10 11 12 13 14
1 Preparing the
Progress
Report
2 Submission of
Progress
Report
3 Poster
Presentation
4 Submission
Final Report’s
Draft
5 Submission of
Final Report

 PROJECT TIMELINE STUDY PLAN:
No. Item/Week 1 2 3 4 5 6 7 8 9 10 11 12 13 14
1 Analysis of
Project’s First
Activity Data
2 Project’s
Second
Activity
3 Analysis of
Project’s
Second
Activity Data
4 Project’s Third
Activity
5 Analysis of
Project’s Third
Activity Data
6 Project’s
fourth Activity

RECOMMENDATIONS:
• Series capacitors are most effective for load variations involving a high
reactive content.
• Overcompensation should be avoided. K = 100 % is not advised for
compensating the line.
• The possibility of oscillations with the downstream loads and transformers
can be reduced by bypassing the capacitor bank prior to the
energizing or reclosing of the distribution circuit.
• The protection of the capacitor bank must be ensured by the use of
overvoltage protective schemes.
•

• In this study, the use of series capacitor compensation method in
distribution networks is suggested to reduce line losses, enhance voltage
profile and gain the ability to increase power transfer capability through
the network.
• The analysis done on simulation basis proved that the technique can
increase the power transfer capability and enhance voltage profile as the
technique has shown high efficiency by the simulation results for the 14
Bus Electrical distribution network.
• The series capacitor unit’s location impact has been proven to be slight
regarding short distance lines and will not have an important impact on
the network.
• Economically, the technique has been justified by the use of incremental
benefit cost ratio analysis associated with public sector projects.
CONCLUSION:

1. T. F. Orchi, M. J. Hossain, H. R. Pota, and M. S. Rahman, "Impact of distributed
generation and series compensation on distribution network," in Industrial Electronics
and Applications (ICIEA), 2013 8th IEEE Conference on, 2013, pp. 854-859.
2. S. Das and D. Das, "Series capacitor compensation for radial distribution networks," in
Innovative Smart Grid Technologies - India (ISGT India), 2011 IEEE PES, 2011, pp.
178-182.
3. L. Morgan, J. M. Barcus, and S. Ihara, "Distribution series capacitor with high-energy
varistor protection," Power Delivery, IEEE Transactions on, vol. 8, pp. 1413-1419,
1993.
4. A. Sweden, "Series Compensation - Boosting transmission capacity," ed, 2005.
5. N. K. R. Wamkeue , J. East , Y.Boisclair, "Series Compensation for a Hydro-Quebec
Long Distribution Line."
6. I. C. Report", "READER'S GUIDE TO SUBSYNCHRONOUS RESONANCE,"
IEEE1992.
REFERENCES:

7. G. C. Baker, "Reconductoring power lines- an example exercise in conductor
selection," in Rural Electric Power Conference, 2001, 2001, pp. D1/1-D1/6.
8. J. S. Hedin and L. H. Paulsson, "Application and evaluation of a new concept for
compact series compensation for distribution networks," in Electricity Distribution,
1993. CIRED. 12th International Conference on, 1993, pp. 1.22/1-1.22/5 vol.1.
9. M. Couvreur, E. De Jaeger, P. Goossens, and A. Robert, "The concept of short-circuit
power and the assessment of the flicker emission level," in Electricity Distribution,
2001. Part 1: Contributions. CIRED. 16th International Conference and Exhibition
on (IEE Conf. Publ No. 482), 2001, p. 7 pp. vol.2.
10. Kaplan, S. M. (2009). Smart Grid. Electrical Power Transmission: Background and
Policy Issues. The Capital.Net, Government Series. Pp. 1-42.
11. H. A. Arun Pachori , Vikendra Moranya , Associat Professor, "Static VAR
Compensation Technique for IEEE 14-bus System," International Journal of
Emerging Technology and Advanced Engineering, vol. Volume 3, August 2013.
REFERENCES:

Viva

Recommended

Recommended

More Related Content

What's hot

What's hot (20)

Similar to Viva

Similar to Viva (20)

Viva