Energy Conservation Techniques to Mitigate the Power Shortage Problem in Pakistan (Case Studies)

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Energy Conservation Techniques to Mitigate the Power Shortage Problem in Pakistan (Case Studies)

Uzma Amin1

Lecturer, Electrical Engineering Department, University of Gujrat, Gujrat, 50700, Pakistan.

Professor Dr. Suhail Aftab Qureshi 2

Head of Electrical Engineering Department, UET, Lahore, Pakistan.

Fariha Durrani3

Lab Engineer, Electrical Engineering Department, University of South Asia.

Abstract

The main objective of this research paper is to show benefits of different energy conservation techniques. As a first case study, I performed analysis on University of Gujrat, electrical power system. This case study involves analysis of motors and tube lights installed at the pumping stations and in Engineering Block of UOG respectively, with the help of energy analyzer before and after the installation of required rating capacitors. Power system analysis also done which includes power distribution system losses for example line losses and copper losses of different rating transformers of UOG. Cost and payback period calculation had been done. Second case study is performed on 11 KV Ali Park and Rachna Town feeders to show fruitful results obtained by implementing rehabilitation techniques on the above said feeders. The results showed by adopting energy conservation techniques not only energy is conserved, it also brings other benefits.

1.0 Introduction

As we know Power shortage is a greatest problem in Pakistan due to different reasons; as a result our nation facing the problem of load shedding. So we as a nation come together towards the solution of this problem and immediate solution lies in the conservation of energy. Our highest priority should be to conserve the energy. The specialty of electrical energy is that it is most convenient form of energy, as it can be transmitted, distributed and utilized over a very large area. The major portion of electricity generated is consumed by the industrial and then residential sector. They have to not only pay the high cost of electricity but also compel to purchase the costly equipment to use in the load shedding hours.

These effects altogether provide strong basis for reducing the electricity consumption. The development of technology will take considerable time as it has many basic problems, technical as well as economical. Thus immediate solution lies in the conservation of energy. As per WAPDA statistics cost of complete installation/ generation of a power house generating one KW of energy is approximately comes out to be US $ 4,50,000 and in Pak. Rupees it id Rs. 43,200,000 (W=where 1 US $ = @Rs. 96). From this statistics report it is cleared that investment made in the field of energy conservation yield in net overall saving along with other benefits. [1,2].

Improving energy efficiency in an electrical system has become the major issue. Because in recent years the nature of load has been changed drastically and large portions of electric machinery i.e. mercury lamps, transformers, motors, switchgears are used to run inherently low power factors which means power supply authorities have to generate much more current that is theoretically required So, in order to accommodate this increasing trend of low power factor & every day increasing load the current level on our system is needed to be reduced and every effort should be made to make this system more energy handling with minimum cost involved.

It may involve different techniques such as improving power factor, changing conductor size, substituting cables with conductor etc. this will lead to reduce copper loss as well as damp the heavy currents with out increasing system size in an efficient way [3].

    1. Energy Analysis of UOG Power System (Case Study-I)

    2. Analysis of (L.T Side of Transformers)

      The calculations were performed by improving the power factor of each transformer installed in the UOG network from 0.7 to 0.95 at full load. Results were observed in the shape of % saving both in terms of KW and KVA. Total KVARs are required to achieve power factor were calculated at the end. Transformers Installed in the UOG Network are as under:-

      1. 25 KVA = 01 No. 2. 50 KVA = 01 No.

      3. 100KVA = 05 Nos. 4. 200 KVA = 20 Nos.

      1. Saving of Transformer at Full Load (200 KVA) Improving Power Factor From 0.7 to 0.9

        1. KVA Saving Calculation (200 KVA Transformer)

          KVA1 = 200

          Cos1 = 0.7

          P = 200 x 0.7 = 140 KW KVAR1 = Sin (Cos-1 0.7) x 200

          = Sin ( 45.57) x 200

          = 142.65 KVAR

          Figure 1 shows the improvement in power factor by providing leading reactive power (KVARs). Practically this can be done by installing an adjustable capacitor in parallel with an inductive load. The load can be adjusted in such a way that the leading current to the capacitor is exactly equal in magnitude to the component of the current in the inductive load which in fact is lagging the voltage by 900. Thus the resultant current is in phase with the voltage.

          140 KW

          25.840

          155.5KVA 67.8

          KVAR

          45.570 142.65

          KVAR

          KVAR2 = Sin (Cos -1 0.9) x 155. = 67.80 KVAR

          KVA1 KVA2 x 100

          Saving in KVA = KVA1

          (200 155.5) x 100

          = 200 = 22.2%

        2. KW Saving Calculation (200 KVA Transformer)

          Figure 2 shows the saving in terms of KW by installing required rating capacitor in parallel with the inductive load. We can save 40 KW by improving power factor from 0.7 to 0.9.

          180 KW

          140 K W 40KW

          25.84

          200 KVA

          Figure 2. Phasor diagram showing saving in KW by installing capacitors of required rating [5].

          For Active Power (KW)

          KW = KVA Cos

          PI = 200 x Cos2

          = 200 x Cos2

          = 200 x 0.9

          = 180 KW

          Saving in KW = 180 140

          = 40KW

          180 140

          %Age saving = 140 x100 = 28.57% Similarly calculations were done to improve the power factor from 0.9 to 0.95. As WAPDA is planning to impose low power factor penalty charges on 0.95 power factor instead of 0.9.

        3. Total KVAR required

200 KVA

74.84

KVAR

KVAR required improving PF from 0.7 to 0.9= 74.84 KVAR for improving PF from 0.9 to 0.95 = 27.84 Total KVAR required for 20 Nos. Transformer

Figure 1. Phasor diagram showing improvement of PF by providing leading KVARs [5].

Cos2 = 0.9

KVA = KW / Cos KVA2 = 140/ 0.9 = 155.5

=102.69×20=2053.8 KVAR

At present there are 20 Nos. of 200 KVA transformers in the UOG network. So for twenty 200KVA transformers in UOG distribution system KVARS required are 2053.8.

      1. Cost of Power Factor Improvement Capacitors

        The cost calculation is done for the installation of capacitors required in improving the power factor to desired level to avoid low power factor penalty charges. Table 1 & 2 shows the market price of both automatic and static capacitors available in different ratings [4].

        Table 1. Market Price of Static Capacitors

        Sr #

        KVAR

        440 VAC

        1

        5 KVAR Capacitor

        Rs. 8000/-

        2

        7.5 KVAR Capacitor

        Rs. 10,000/-

        3

        10 KVAR Capacitor

        Rs. 16,000/-

        4

        12.5 KVAR Capacitor

        Rs. 19,500/-

        5

        25 KVAR Capacitor

        Rs. 32,000/-

        6

        50 KVAR Capacitor

        Rs.50,000/-

        7

        100 KVAR Capacitor

        Rs. 90,000/-

        Table 2. Market Price of Automatic Capacitors

        Sr #

        KVAR

        440 VAC

        1

        25 KVAR Capacitor

        Rs. 51,080/-

        2

        50 KVAR Capacitor

        Rs. 91,200/-

        3

        100 KVAR Capacitor

        Rs. 149,680/-

        1. Cost of Capacitors Required for (200 KVA) Transformers at Full Load

          Required KVARS for 1 # 200 KVA Transformer

          = 103 KVAR

          Total KVARS for twenty #200 KVA Transformers

          = 2060 KVAR

          Whereas

          Cost for 100 KVARS 440 VAC Static Capacitor

          = 90,000 Rs/-

          Total cost of static capacitors for 20 Nos. transformers is: = Rs. 20x 90,000

          = Rs. 1,800,000/-

          Whereas

          Cost for 100KVAR 440VAC Automatic Capacitor

          = 149,680 Rs/-

          Total cost of automatic capacitors for 20 Nos. transformers is: = 20 x 149,680

          = Rs. 2,993,600 /-

        2. Cost of Capacitors Required for (100 KVA) Transformers at Full Load

          Required KVARS for 01# 100 KVA Transformer

          = 51 KVAR

          Total KVARS for 05 # 100 KVA Transformers

          = 255 KVAR

          Whereas

          Cost for 50 KVAR 440 VAC Static Capacitor

          = Rs. 50,000/-

          Total cost of static capacitors for 05 Nos. transformers is: = 05 x 50,000 = Rs. 250,000/- Whereas

          Cost for 50 KVAR 440 VAC Automatic Capacitor

          =Rs. 91,280

          Total cost of automatic capacitors for 05 Nos. transformers are: = 05 x 91.28 = Rs. 456,400/-

          = Rs. 2,993,600 /-

          Similarly calculations were done for 50 and 25 KVA Transformers respectively.

          Hence Total Cost for all the Static Capacitors:

          1. 01 x 25 KVA Transformer =Rs. 19,500/-

          2. 01 x 50 KVA Transformer=Rs. 32,000/-

          3. 05×100 KVA Transformers=Rs. 250,000/-

          4. 20x200KVATransformers=Rs. 1,800,000/-

          Grand Total = Rs. 2,101,500/-

          Hence Total Cost for all the Automatic Capacitors:

          1. 01 x 50 KVA Transformer = Rs. 50,070/-

          2. 05×100 KVA Transformers=Rs. 456,400/-

          3. 20x 200 KVA Transformers = Rs. 2,993,600/-

          Grand Total = Rs. 3,500,070/-

    1. Energy Analysis of Motors

      For the comprehensive and complete analysis of motors installed at the pumping stations of the UOG, energy analyzer equipment was used. In the analysis procedure energy analyzer was attached with the motor installed while keeping the load on the motor ON and complete set of data was obtained showing the frequency, current in each phase, line current, line voltage in each phase, power factor, active power, apparent power, reactive power, distortion factor, KWH, KVARH etc. This analysis was done to calculate what ratings of capacitors are required for the power factor improvement in addition to other outputs.

      The complete set of analysis, which was done with the energy analyzer of all the motors installed in the pumping station, has been shown below in the tabular form. The final analysis after the installation of the required capacitors was done again to check the

      power factor improvement and what effects does this procedure has on the improvement of power factor. It was observe that power factor of the motors has been increased remarkably moreover other factor like voltage increase, current drawn decreases, decrease of KVA rating etc. Results of the analysis before and after the installation of capacitors have been shown below in Table 3.

      So net % age difference in current decrease.

      = x 100

      = x100 = 16.14 %

      Step III

      Voltage before the installation of capacitor = 378.8V Voltage after the installation of 20 KVAR capacitor

      =384.18V

      Comparison of Different Parameters of Water Supply Motors before and after the Installation of Capacitors by Computerized Energy Analysis

      1. Water Supply Motors

      P = 40 HP, V = 415 Volts, I = 60 Amps.

      Phase

      Current

      (Amps)

      Voltage

      (Volts)

      Power

      Factor

      Before

      After

      Before

      After

      Before

      After

      L1

      59.3

      49.9

      380.2

      385.8

      0.843

      0.971

      L2

      57.6

      48.1

      378.7

      384.0

      0.841

      0.981

      L3

      60.2

      50.5

      377.5

      382.7

      0.846

      0.984

      Mean

      59.03

      49.50

      378.8

      384.1

      0.843

      0.979

      Table 3. Showing Energy Analysis of Water Supply Motor

      Phase

      Active Power (KW)

      Reactive Power (KVAR)

      Apparent Power (KVA)

      Before

      After

      Before

      After

      Before

      After

      L1

      10.97

      10.79

      7.06

      2.66

      13.02

      11.12

      L2

      10.95

      10.46

      6.83

      2.55

      12.59

      10.67

      L3

      11.10

      10.98

      7.11

      2.67

      13.12

      11.16

      Total

      32.67

      32.24

      20.99

      7.87

      38.73

      32.94

      Calculations:

      Step -I

      P.F before the installation of capacitor = 0.843

      P.F after the installation of 20 KVAR capacitor

      = 0.979

      So net % age increase of power factor = x 100

      = x 100

      = 16.13 %

      Step II

      Current before the installation of capacitor = 59.03 A Current after the installation of 20 KVAR capacitor

      = 49.50A

      So net % age difference in voltage increase

      = x 100

      = x 100 = 1.42%

      Step IV

      KVA before the installation of capacitor

      = 38.73 KVA

      KVA after the installation of 20 KVAR capacitor

      = 32.94 KVA

      So net % age difference in KVA decrease

      = x 100

      = x 100 =14.94%

      There are three 40 HP water supply motors in University of Gujrat. Preceding analysis describes the energy analysis of one 40 HP motor. Other two 40 HP motors have the same energy analysis.

    2. Energy Analysis of Different Loads Installed in Engineering Block Building of UOG

In order to implement the power factor improvement technique, analysis was made on the engineering block building with the help of energy analyzer after putting the entire load in ON condition at different time intervals.

Although building and effects were calculated with the help of energy analyzer. analysis is quite tricky because of variety of electrical equipment (different loads) has been installed in the engineering block building moreover due to large usage, load conditions vary from time to time. As an exercise, analysis was also made of the tube lights (inductive loads) installed in the engineering

Observations were taken after the installation of 4.5uF capacitor. As a sample case capacitor was installed on tube-lights at three to four different locations in the engineering block building. These observations were taken individually on each floor and effects were examined individually on each tube-

light. It was obsrved that tube-lights fitted with 4.5uF shows improvement in power factor. If this procedure is repeated on all the installed tube lights in the engineering block building, it will bring a worth value improvement in the system capacity. The results taken have been placed in the tabular form below. It was observed that power factor of the total system has been increased, other factors like voltage increase, decrease of KVA rating etc. Results of the analysis before and the installation of capacitors have been shown in the table 4 below.

Total no of tube lights in engineering block = 247 The detail is as under:

Ground Floor: Total no of tube lights = 89 First Floor: Total no of tube lights = 89 Second Floor: Total no of tube lights = 89

2.3.1. Computerized Energy Analysis & Comparison of Engineering Block Building Before and After the Installation of Capacitors

1. First Floor Analysis

P = 40 x 247 = 7.88 KW, Vp = 221.63 Volts

I = 74.1 Amps (0.3 Amps each)

Table 4. Showing Energy Analysis of First Floor of Engineering Block Building

Calculations:

Step I

P.F before the installation of capacitor = 0.810

P.F after the installation of 35 KVARs capacitor

= 0.971

So net % age increase of power factor

= x 100

= x100 = 19.87 %

Step II

Current before the installation of capacitor = 85.23 A Current after the installation of 35 KVAR Capacitors

= 75.70 A

So net % age difference in current decrease.

= x 100

= x 100 = 12.58 %

Step III

Voltage before the installation of capacitor = 379.9V Voltage after the installation of 35 KVAR capacitors

=385.35V

So net % age difference in voltage increase

= x 100

= x 100 = 1.40%

Phase

Current (Amps)

Voltage (Volts)

Power Factor

Before

After

Before

After

Before

After

L1

85.2

75.8

368.5

374.1

0.795

0.974

L2

70.3

60.8

395.1

400.4

0.825

0.987

L3

100.2

90.5

376.3

381.5

0.811

0.951

Mean

85.23

75.70

379.9

385.4

0.810

0.971

Step IV

KVA before the installation of capacitor = 55.93 KVA after the installation of 35 KVAR capacitors

= 50.36 KVA

So net % age difference in KVA decrease

= x 100

Phase

Active Power

(KW)

Reactive

Power (KVAR)

Apparent

Power (KVA)

Before

After

Before

After

Before

After

L1

14.41

15.59

13.02

3.70

18.13

16.37

L2

13.23

13.87

12.59

2.25

16.04

14.06

L3

17.76

18.96

13.12

6.16

21.77

19.93

Total

45.30

48.78

38.73

12.11

55.93

50.36

= x 100 = 9.95%

Similarly analysis was done for tube lights installed in 2nd and third floor. For above analysis we can see that improvement in PF has been done just after installing the 4.5uF capacitor on each tube light but it is difficult to analyze the total load

    1. Energy Analysis Calculations of

      U.O.G Power System

      Low power factor results in the form of penalty by the WAPDA. Investments in the power factor improvement are made to avoid the low factor

      penalty charges. However, in WAPDA and KESCO where the electric utilities have a penalty based rate structure, power factor correction capacitor and systems can generate a one-year or less payback.

    2. Analysis of U.O.G Power System

      Due to the power factor UOG pays huge amount as penalty charges to WAPDA. By proper adopting a technique for power factor improvement, penalty charges can be avoided. WAPDA has fixed 0.90 power factor for the consumers and any consumer having power factor less than the prescribed value has to pay the penalty and WAPDA is planning to increase its power factor to 0.95. As per WAPDA tariff structure is concerned, UOG electricity load falls in the C2 (A) type, (Tariff 28) category whose formula for finding the low power factor LPF is as under.

      Penalty = Energy Charges * (0.9 – Power Factor)

      Energy Charges = KWh Units * Unit Rate

      (Rs. 8.65 from Tariff Table)

      Hence the penalty along with the cost of capacitors to avoid penalty charges is calculated. Then the tentative recovery payback period is also calculated. For energy analysis of U.O.G distribution system detail drawing showing all electrical equipment like transformers, motors etc with ratings along with their respective distances from the source were drawn that will facilitate in the calculation work. Results like current drawn, KVAR required to achieve this power factor and saving in KVA and saving in terms of cost due to power factor penalty will be calculated at the end.

    3. Analysis of U.O.G Electricity Bills

      For calculating the reduction / saving in the bills of UOG, complete energy analysis of UOG distribution system was essential and for this purpose electricity bills of UOG for the twelve months from July, 2010 to June, 2011 were analyzed. Table 5 shows the detail of data available from electricity bill of UOG for the year (2010/11).

      Table 5. Showing various Units Consumed / Year (2010/11)

      Month

      / Year

      KW

      KWH

      KVARH

      P.F1

      31.07. 10

      640

      175040

      113066

      0.84

      31.08. 10

      640

      162560

      105000

      0.84

      30.09. 10

      640

      133360

      103499

      0.79

      30.10. 10

      640

      134880

      111765

      0.77

      30.11. 10

      480

      110560

      109657

      0.71

      30.12. 10

      480

      130480

      111582

      0.76

      27.01. 11

      480

      140960

      124315

      0.75

      26.02. 11

      640

      110080

      65318

      0.86

      28.03. 10

      2400

      125200

      80871

      0.84

      27.04. 10

      160

      120560

      109580

      0.74

      27.05. 10

      640

      176800

      95427

      0.88

      25.06. 10

      16352

      197280

      158274

      0.78

      1. Data Available (From Electricity Bill) of January, 2011.

      Year/Month = 1 / 2011

      KW = 480

      KWH = 140960

      KVARH = 125600

      Load factor = KWH ( 730 x KW )

      = 140960 / ( 730 x 480)

      = 0.40

      P.F1 = Cos(Tan-1(KVARH/KWH)

      = Cos(Tan-1(125600/140960)

      = 0.75

      KVA Load

      =

      =

      KW / P.F1 480 / 0.75

      =

      640

      PF2

      =

      0.95

      KVAR1

      =

      =

      KW(Tan(Cos-10.75))

      480(Tan(Cos-10.75))

      KVAR2

      =

      =

      =

      423.32

      KW(Tan(Cos-10.95))

      480(Tan(Cos-1 0.95))

      =

      157.77

      KVAR required

      =

      =

      KVAR1 – KVAR2

      423.32 – 157.77

      =

      265.55

      KVA Saving

      =

      =

      KW(1/P.F1 – 1 / P.F2 )

      480 (1/ 0.75 – 1 / 0.95)

      =

      134.74

      WAPDA imposes penalty on the consumer having power factor less than 0.9 and for that WAPDA has divided its tariff as per load type and UOG tariff type C2 (A) 28 of which unit rate penalty is 8.65.

      TF4 = 172M

      TF5 = 140M

      TF6 = 201M

      TF7 = 157M

      TF8= 050M

      TF9=091M

      TF10= 44M

      TF11 = 52M

      TF12 = 151M

      TF13= 038M

      TF14= 93M

      TF15=425M

      TF16 = 302M

      TF19 = 265M

      TF17= 261M

      TF20 = 94M

      TF18 = 389M

      Penalty Charges = Total Energy charges x P.F [7].

      Whereas

      Penalty Charges=KWH Units x8.65 x (0.9 – P.F)

      = 140960 x 8.65 x (0.9 – 0.84)

      = Rs. 182,895.60/-

      Similarly all the Calculation were made for different monthly data obtained from Bill.

      Total Penalty=Rs1,461,151.08/-(for 12-months)

    4. Cost and Payback Period Calculations Maximum KVARs were observed in March, 2011 = 761.41

Static Capacitors required to Provide 761.41 KVARS

= 7×100 KVARs +1×50 KVAR +1×25 KVAR.

Cost of 100 KVAR Static Capacitor=Rs.90,000/- Cost of 50 KVAR Static Capacitor= Rs.50,000/- Cost of 12.5 KVAR Static Capacitor= Rs.9,500/- Total Cost = 630,000 + 50,000 + 19,500

= Rs. 699,500/-

Pay Back Period for the Static Capacitors are five months.

3.3.2 Automatic Capacitors Requirement and Pay Back Period Calculation

Automatic Capacitors required to Provide 761.41 KVARS = 7×100 KVARs + 1x 50 KVAR + 1x 25 KVAR.

Cost of 100 KVAR Automatic Capacitor

= Rs 149,680/-

Cost of 50 KVAR Automatic Capacitor

=Rs. 91,280/-

Cost of 25 KVAR Automatic Capacitor

=Rs. 50, 070/-

Total Cost = 149,680 + 91,280+ 50,070

=Rs. 1,189,110/-

Pay Back Period for the Automatic Capacitors are eight months.

    1. Power Distribution System Losses of University of Gujrat

      For calculating HT line losses in the distribution system of UOG, exact length of the HT line from the source to the transformer is measured from the electrical design map of the UOG.

    2. Overall Reduction H.T Line losses Connected to 200 KVA Transformers

Length of HT Cable from the source

TF1 = 82M TF2 = 123M TF3 =139M

Resistivity of dog conductor=0.000391 / Meter

4.1.1 Reduction in HT line losses Connected to TF1 (200 KVA)

Power losses at P.F1 (0.7) = (I1)2 xR x Length

=(10.497)2×0.000391x 82

= 3.533 Watts

Power losses at P.F2 (0.95)= (I2)2 x R x Length

= (7.735)2 x 0.000391x 82

= 1.918 Watts Reduction in HT line losses= 3.533 – 1.918

= 1.615 Watts

% Age Reduction in HT Line Losses = (3.533- 1.918)

1.746

= 45.69%

Similarly Calculation were done for all 200, 100, 50 and 25 KVA Transformers.

    1. Transformer Copper Losses

      Distribution transformers generally have two types of losses

      1. Copper losses (I2.R Losses)

      2. Iron losses (Fixed losses)

        Copper losses are proportional to the square of the load currents [6].

        Standard Distribution Transformer losses at different loading are given in the table 6 below.

        Table 6. Standard Distribution Transformer Losses at Different Loading

        T/F Capacity (KVA)

        Max Current

        (Amps)

        %Age Load vs. Losses in Watts

        25%

        50%

        75%

        100%

        125 %

        150%

        25

        50

        36

        72

        130

        248

        234

        468

        425

        833

        71

        1345

        1001

        2003

        1403

        2807

        100

        144

        436

        815

        1346

        2330

        3466

        4855

        200

        288

        708

        1320

        2413

        3905

        5823

        8167

    2. Reduction is Copper losses of 200 KVA Transformer

KVA before P.F improvement at 0.75 = 200 KVA KVA after P.F improvement at 0.95=157.89 KVA Reduction in KVA after improvement = (200 157)

47

= 26.3 %

Standard losses at 100% load =3905 Watts (From table)

Standard losses at 75% load =2413Watts Reduction in copper losses = (3905 2413)

= 1492Watts (3905 2413) x 100

%Age reduction = 3905

= 38.2%

Total reduction for 20 x 200 KVA transformers = 20 x 1492 = 29840 Watts.

5.1.1 Overall Reduction in Copper Losses

(i) Total reduction of Copper Losses for 1 x 25 KVA transformer = 1×285 Watts.

  1. Total reduction of Copper Losses for 1 x 50 KVA transformer = 1 x 512 Watts.

  2. Total reduction of Copper Losses for 5 x 100 KVA transformer = 5×984=4920 Watts.

  3. Total reduction of Copper Losses for 20 x 200KVA transformer=20×1492= 29840 W.

Total saving in Copper losses of all transformers = 285+512+4920+29840 = 35,557Watts

Units saving per day = (35.55 x24)

= 853.6 KWH

Units saving per month = (35.55 x 24 x 30)

= 25,601.04 KWH

Units saving per year = 311,479.32 KWH

6.0 Total Saving Analysis of Transformers

Following are the overall results of the above mentioned calculations. Table 7 shows the saving in terms of kW and kVA by improving power factor.

Table 7. Saving in terms of kW & kVA by power factor improvement.

KVA

Power (KW)

Power Factor (Cos)

KVAR

Required at 0.95 PF

Before

After

Before

After

Before

After

25

19.74

18.75

23.75

0.75

0.95

13

50

39.47

37.5

47.50

0.75

0.95

25

100

78.95

75

95

0.75

0.95

50

200

157.89

150

190

0.75

0.95

100

Total KW before power factor improvement (0.75 P.F) = 2401.7

Total KW After power factor improvement (0.95 P.F)

=3259. 45

Total savings =(32592401) =857 KW

(3259 2401)

Total Saving in KW(%age) = 2401x 100

= 35.7 %

Total cost of installation /generation of power house

=US Dollars 450/KW

So Total cost for generation of 857KW of energy = 857x 450 = US $ 405,000 = Rs. 96 x 405,000

Total saving in terms of Pak Rupee

= Rs.38,800,000/-

Total KVA before power factor improvement (0.75 P.F) = 3431

Total KVA after power factor improvement (0.95 P.F) = 2528

(3431 2528) x 100

Total Saving in KVA =

3431

= 26.3%

Total HT line losses of all transformers at 0.75 P.F1=

175.90 Watts.

Total HT line losses of all transformers at 0.95 PF2 =

    1. Watts.

      Reduction in HT line losses = 175.90 95.39

      = 80.509 Watts.

      (175.90 95.39) x 100

      1. 25 KVA Transformer = 01 No.

      2. 50 KVA transformers = 01 Nos

      3. 100 KVA transformers = 5 Nos

      4. 200 KVA transformers = 20 Nos

%Age reduction =

= 45.76%

175.90

6 .1 Overall saving Analysis by Power Factor improvement on L.T Side of Transformers

Case I: (As Per General Analysis)

  1. Unit saving/year due to transmission line losses = 705.2 KWH

  2. Units saving/year due to transformers copper losses = 9,344,380 KWH

Total saving/year in units due to power factor improvement =9,345,085 KWH.

Whereas rate/unit = Rs.8.69/-

Total saving/year = 9,345,085×8.69

= Rs. 81,208,790.39

Case II (As per Actual Consumption During Year 2010-2011)

Total penalty charges due to low power factor for 12 months = Rs. 1,461,151.08/-

    1. Energy Loss Reduction and Cost Benefit Analysis by Implementation of Rehabilitation Technique (Case-II)

      This part of paper includes the area planning and bifurcation of 11KV Ali Park and 11 KV Rachna town feeder emanating from 132 KV Shamkey Grid Station. The main purpose of this case study is to give relief to the subject feeders by implementing rehabilitation techniques which may not withstand the heavy load in the summer season. This case study shows that by implementing rehabilitation techniques how much energy can be conserved by reducing power losses. The strategy is to minimize technical losses which in turn minimize total losses in an electrical distribution network.

      Increasing energy costs and environmentalists actions to protect the natural resources force energy supply companies to conserve and reduce energy usage. Therefore the study focused on the reduction of electrical energy losses in distribution networks. Reducing these losses ensure that the cost of electricity to customers will be reduced and in turn improve the efficiency of the distribution network.

    2. Data Collection

      The data collected to carry out the analysis for the project is taken from the distribution facility (LESCO). This data covers the High Tension (HT) Line information of 11 KV Ali Park and Rachna

      Town Feeders which is required for generating single line diagram. HT Line information includes:

      1. Node to node distance in meter

      2. Conductor Type (PANTHER, DOG, RABBIT etc.)

      3. Transformer Rating in KVA

      4. Capacitor Rating in KVAR

    3. Silent Features/ Technical Parameters

The case study involves following 11 KV feeders for rehabilitation.

      1. 11 KV Ali Park Feeder

        Its a mixed load feeder having small industrial, commercial and agricultural / rural load on it. The length of the feeder is 30.5 Km having 400 amps load on it.

      2. 11 KV Rachna Town Feeder

        Its a mixed load feeder having small industries and city load on it. The length of the feeder is 13.3 Km having 330 amps load on it.

        The above mentioned feeders have also have deteriorated / off size conductors.

    1. Benefit/ Cost Calculation

      For Reconductoring, Bifurcation and Area Planning proposals B/C >= 2 [8,9].

      1. B/C Calculation for Area Planning and Bifurcation of 11 KV Ali Park and Rachna Town Feeder

Without Growth

Saving in Losses due to Bifurcation of Load,S1

= 335.800 KW

Saving in Losses due to Fixed Capacitor Banks S2 = 0 KW

Saving in Losses due to Switched Capacitor Banks,S3=0 KW

Saving in Losses due to Reconductoring, S4

=0 KW

Total Saving in Losses without Growth S5

=335.800 KW

With Growth

Saving in Losses with Growth:

[(((S1+S4)x F)+(S2+S3))], S6 = 401.6168 KW

Where, F = Growth Factor = 1.196 @ 5% growth for 5 years.

Value of benefits with growth: VFxS6 ,S7 = 5714622.8

Where, VF = Valuation Factor = Losefactorx8760xelectricity purchase rate =

Rs.14229.0432 kW/Annum New facility Cost, NFC = Rs. 10070711 Replaced Facility Cost, RFC = Rs. 299151

Benefit Cost Ratio

B/C Ratio = Benefit Cost Ratio = 3.7

So the proposal is technical and economical [8,9].

    1. Proposed 11 KV Industrial Feeder

      A new feeder namely 11 kV industrial (P) feeder is proposed from 132 kV Shamkey Grid Station which will cater 3.13 km & 4500 connected kVA of 11 kV Ali Park Feeder and 4.54 km & 3320 connected kVA of 11 kV Rachna Town Feeder.

      The new proposed feeder will be mix load feeder with mostly small industries like flour mills, marriage hall etc. the rural / agricultural load of 11 kV Ali Park feeder is proposed to be separated from the industrial load by shifting the later on new proposed 11 kV industrial feeder. Table below describes the technical parameters detail containing existing, existing modified and proposed position of feeders and overall savings / improvement

    2. Existing Position of Feeders

      Table 8 shows technical parameter detail of 11 kV Ali Park and Rachna Town feeders before applying rehabilitation technique.

      Table 8. Existing position of 11 KV Ali Park and Rachna Town Feeder

      Feeder

      Grid Station

      Length

      Connected

      Peak

      Load

      Voltage

      Drop

      (KM)

      (KVA)

      (A)

      (%)

      Ali Park

      (Ext)

      132 kV

      Shamkey

      30.539

      15465

      400

      10.8%

      Rachna Town

      (Ext)

      132 kV

      Shamkey

      13.326

      9325

      330

      8.2%

      Total

      43.865

      24790

      730

    3. Proposed Position of Feeders

Table 9 shows the position of feeders after proposing new feeder namely Industrial Feeder emanating from 132 kV Shamkey Grid Station which will cater 4500 & 3320 connected kVA of 11 kV Ali Park & Rachna Town feeders respectively. The table shows technical parameter detail and overall saving or improvements

Table 9. Proposed positions of 11 KV Ali Park, Rachna Town and Industrial Feeder

Feeder

Grid Station

Line / Load / Connected KVA Shifted From

Feeder

Length

(KM)

Connected

(KVA)

Load

(A)

Ali Park (Ext)

132 kV

Shamkey

Ali Park

27.41

10965

226

New

Line

2.16

S/Total

29.57

10965

226

Rachna Town (Ext)

132 kV

Shamkey

Rachna Town

8.79

6005

213

S/Total

8.79

6005

213

Industrial (P)

132 kV

Shamkey

Ali

Park

3.13

4500

93

Rachna

Town

4.54

3320

117

New

Line

6.66

Idle

Line

0.22

S/Total

14.55

7820

210

Total

Total

43.865

24790

730

Feeder

Grid Station

Voltage Drop

Power Loss

Annual Energy

Loss

Loss

Loss

%

%

%

KW

KWh

Ali Park (Ext)

132 kV

Shamkey

5.4

2.57

1.85

94.1

356065

Rachna

Town (Ext)

132 kV

Shamkey

2.7

1.66

1.20

57.4

217140

Industrial (P)

132 kV

Shamkey

4

2.67

1.92

90.7

343140

Total

2.30

1.66

242

916345

Feeder

Grid Station

Power Loss

Annual Energy

Loss

Loss

Loss

(%)

(%)

(KW)

(KWH)

Ali Park

(Ext)

132 kV

Shamkey

5.8

4.2

376.3

1424091

Rachna Town

(Ext)

132 kV

Shamkey

3.8

2.7

201.7

763358

Total

578

2187449

    1. Analysis of 11 KV Ali Park Feeder

      1. At Actual (400 A) Load Existing Position

        The technical losses at this actual load on the feeder are calculated as:

        i. Technical losses at this load without bifurcation, re-conductoring and capacitor bank installed are

        376.1 kW.

      2. At Proposed (226 A) Load Existing Modified Position

        The technical losses at this proposed load on the feeder are calculated as:

        1. Technical losses at this load without re- conductoring and capacitor bank installed are 124.1 kW

        2. Technical losses at this load with re-conductoring at N-38 & N-115 and with a capacitor bank of 450kVAr installed at N75, N-125 & N148 are

        94.0 kW.

      3. Analysis of 11 kV Rachna Town Feeder

        1. At Actual (330 A) Load Existing Position The technical losses at this actual load on the feeder are calculated as:

          i. Technical losses at this load without bifurcation, re-conductoring and capacitor bank installed are

          201.6 kW.

        2. At Proposed (213 A) Load Existing Modified Position

The technical losses at this proposed load on the feeder are calculated as:

  1. Technical losses at this load without capacitor bank installed are 71.0 kW

  2. Technical losses at this load with a capacitor bank of 450kVAr installed at N54 & N-128 are 57.3 kW.

7.6.4 Analysis of 11 kV Industrial Feeder Proposed

7.6.4.1 At Proposed (210 A) Load

The technical losses at this proposed load on the feeder are calculated as:

  1. Technical losses at this load without re- conductoring and capacitor bank installed are 139.4 kW.

  2. Technical losses at this load with re-conductoring at N-1.0, N-176, N-177, N-178, N-180, N-181, N- 183, N-188, N-189, N-211 & N-229-231 and with a capacitor bank of 450kVAr installed at N208, N-229 & N234 are 89.4 kW.

7.6.5 Reduction in the Technical Losses (11 KV Ali Park Feeder)

Reduction in the technical losses due to re- conductoring and installation of capacitor banks are described as under:

7.6.5.1 At Proposed (226 A) Load

  1. Loss without re-conductoring and without any capacitor bank installed is 124.1 kW.

  2. Loss with re-conductoring and a capacitor

banks of 450kVAr installed are 94.0 kW. Reduction in losses is:

124.1KW 94.0 kW = 30.1 kW = 30.1 kW x 100

124.1 kW

7.6.6 Reduction in the Technical Losses (11 KV Rachna Town Feeder)

Reduction in the technical losses due to installation of capacitor banks are described as under:

7.6.6.1 At Proposed (213 A) Load

  1. Loss without any capacitor bank installed is 71.0 KW.

  2. Loss with a capacitor banks of 450kVAr installed are 57.3 kW, Reduction in losses is:

71.0 kW 57.3 kW = 13.7 kW = 13.7 kW x 100

71.0kW

= 19.26%

7.6.8 Reduction in the Technical Losses (11 KV Industrial Feeder Proposed)

Reduction in the technical losses due to installation of capacitor banks are described as under:

7.6.8.2 At Proposed (210 A) Load

  1. Loss without re-conductoring and any capacitor bank installed are 139.4 KW.

  2. Loss with re-conductoring and capacitor banks of 450 kVAr installed are 89.4 kW.

Reduction in losses is:

139.4 kW 89.4 kW = 50 kW = 50.0 kW x 100

139.4 kW

= 35.86%

    1. Conclusion

      From the preceding analysis (first case study) one can conclude that by adopting P.F improvement technique on the L.T side of the transformer not only relieved the UOG power system from the lower power factor penalty charges imposed by WAPDA but can brings the following advantages:

      1. Reduction in KVA demand (27.48%)

      2. Reduction in energy losses of transmission lines (45.70%)

      3. Total saving in KW (27.46%)

      4. Saving is terms of Units (KWH) is 9,345,085 KWH

The best technique to conserve energy in UOG power system is by power factor improvement. Implementation of Rehabilitation Techniques is not necessary because voltage drop across H.T Line is within WAPDAs standard up to 3%.

Second case study shows the best technique to conserve energy in LESCO system is by implementation of rehabilitation techniques.

By applying rehabilitation techniques (second case study) on 11 kV Ali Park and Rachna Town feeders gives a healthy benefit cost ratio 3.7.

LESCO can save 336 kW active power and 1,271,104 KWH energy units annually. Voltage drop, power losses and annual energy loss reduces from 10.8% to 5%, 3.5% to 2.3% and 4.9% to 1.6%

respectively.

Hence power factor improvement and rehabilitation techniques are both useful to conserve the energy depending on the power system requirement.

Recommendations

Work related to this thesis can be preceded, if the software were further enhanced in the direction to make it more dynamic. Graphical representation of power losses, current, voltage, power factor and cable network can be incorporated moreover it could be intelligent enough to show at which point analysis has been done.

11 KV Ali Park and Rachna Town Feeders, emanating from 12 kV Shamkey Grid Station are not capable to withstand the heavy load in summer. Therefore a new feeder namely, 11kV Industrial feeder is proposed to shift load from 11 kV Ali Park and Rachna Town Feeders.

Itis also recommended that all DISCOS may rehabilitate its existing system to achieve fruitful results and there is also need to identify and promote the policies that can motivate and create awareness of energy conservation policies on sustainable basis.

9.0 References

  1. Ather Jamil Dar, Energy Conservation Techniques and Economy Analysis for U.E.T Electrical system, MSc Thesis, U.E.T Lahore, 1999.

  2. Dr. Suhail. A. Qureshi, U.E.T Lahore, Efficient Power Factor Improvement Technique & Energy Conservation of Power system, published by IEEE (USA) Singapore, 1996.

  3. Dr. Suhail. A. Qureshi, M.Kamran, Farhan Mahmood, Energy Conservation Techniques and Implementation of Power Factor Improvement Program, Published in new Horizon, Journal of the Institution of Electrical & Electronics Engineer Pakistan, Vol # 50-51 October 2005 to March 2006, (P-42).

  4. Data from Various Local and Foreign Manufacturers of Capacitors.

  5. Van Valkenbuegh Nooger & Neville Inc Basic Electricity Part one to part five Combined, 3rd Edition, Publication by Universal Publication Corporation, India.

  6. Dr. Suhail. A. Qureshi, Abdul Sattar Malik, Zahid J Paracha, Impact of Power Factor Improvement Program on Motors in U.E.T Distribution System Published in UET Research Journal, Vol # 15, Lahore Pakistan, Nos (1-2) January 2004 to December 2004, (P-39).

  7. Dr. Suhail. A. Qureshi, M.Kamran, Farhan Mahmood, Role of Masses of Conserve Energy by Power Factor Improvement & Formation of Govt-Policy Presented in UCP IEEP, Multi Topic Conference, May-2, 2009, Lahore, (P191).

  8. ENERCON, Improving Energy Efficiency In Electrical System, National Energy Conservation Center, Islamabad, 2003.

  9. Muhammad Amin, Evaluation by Implementation of Distribution System Planning for Energy Loss Reduction , MSc Thesis, 2006.

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