SECONDARY DISTRIBUTION SYSTEM OPTIMIZATION METHODOLOGY AND MATLAB PROGRAM A Project Presented to the faculty of the Department of Electrical and Electronic Engineering California State University, Sacramento Submitted in partial satisfaction of the requirements for the degree of MASTER OF SCIENCE in Electrical and Electronic Engineering by Steve Ghadiri Majid Hosseini FALL 2013
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SECONDARY DISTRIBUTION SYSTEM OPTIMIZATION METHODOLOGY
AND MATLAB PROGRAM
A Project
Presented to the faculty of the Department of Electrical and Electronic Engineering
VDSD-Service Drop 0.721 1.0826 0.772 1.158 0.3705 0.555
59
Table 6.1 --Summary of the Runs Continued
(Source Provided by Authors)
i=10% Run 37 Run 38 Run 39 Run 40 Run 41 Run 42
Low Electric Markup ,
ECoff= 0.015, ECon =
0.02, Power Factor = 0.9
Class 1
10,12,18
kVA
SL=320ft
SD=80ft
Class 1
10,12,18
kVA
SL=480ft
SD=120ft
Class 2
4.4,6,10
kVA
SL=320ft
SD=80ft
Class 2
4.4,6,10
kVA
SL=480ft
SD=120ft
Class 3
1.2,1.5,2.5
kVA
SL=320ft
SD=80ft
Class 3
1.2,1.5,2.5
kVA
SL=480ft
SD=120ft
Optimized * *
ST-kVA 80.94 80.94 38.71 38.71 13.217 13.217
ASL-kcmil 267.19 267.19 133.59 133.59 33.4 33.4
ASD-kcmil 141.7 141.29 78.72 78.72 19.68 19.68
TAC-$ 8127 10447 4750 6005 2254 2626
Standard
ST-kVA 100 100 50 50 15 15
ASL-kcmil 350 300 205 300 66.36 105.6
ASD-kcmil 167.8 Out 83.69 83.69 41.74 41.74
TAC-$ 8230 Of 4827 6099 2349 2626
Voltage Drop Bound
Total -percentage (%) 5.37 4.69 7.85 4.27 4.40
VDT-Transformer 2.40 1.90 1.90 1.82 1.82
VDSL-Service Lateral 2.28 2.06 4.80 2.08 2.03
VDSD-Service Drop 0.68 0.74 1.16 0.36 0.54
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Table 6.1 --Summary of the Runs Continued
(Source Provided by Authors)
i=15% Run 43 Run 44 Run 45 Run 46 Run 47 Run 48
Low Electric Markup ,
ECoff= 0.015, ECon =
0.02, Power Factor = 0.9
Class 1
10,12,18
kVA
SL=320ft
SD=80ft
Class 1
10,12,18
kVA
SL=480ft
SD=120ft
Class 2
4.4,6,10
kVA
SL=320ft
SD=80ft
Class 2
4.4,6,10
kVA
SL=480ft
SD=120ft
Class 3
1.2,1.5,2.5
kVA
SL=320ft
SD=80ft
Class 3
1.2,1.5,2.5
kVA
SL=480ft
SD=120ft
Optimized * *
ST-kVA 80.48 80.48 38.5 38.5 13.15 13.15
ASL-kcmil 262.4 262.4 131.2 131.2 32.8 32.8
ASD-kcmil 139.14 139.14 77.31 77.31 19.33 19.33
TAC-$ 11968 15387 7016 8866 3350 3901
Standard
ST-kVA 100 100 50 50 15 15
ASL-kcmil 350 300 205 300 66.36 66.36
ASD-kcmil 167.8 Out 83.69 83.69 41.74 41.74
TAC-$ 12142 Of 7086 8939 3498 4120
Voltage Drop Bound
Total -percentage (%) 5.37 4.70 4.94 4.27 4.40
VDT-Transformer 2.40 1.90 1.90 1.82 1.82
VDSL-Service Lateral 2.28 2.06 1.92 2.08 2.03
VDSD-Service Drop 0.68 0.74 1.11 0.36 0.54
We made sure we run the program for at least several cases. We also subjected the
runs to the constraints of at least five (5) percent voltage drop for service lateral, and 10
percent overall.
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We first ran the Matlab program (OptimizeTAC) for class 3 residence customer,
as specified in the Table 4.1 (reflecting Table 6.4 of the Dr. Gonen’s Distribution book
[1], and as provided earlier here in this paper. The program (OptimizeTAC) reached a
solution and gave a 15-kVA transformer with a No. 4 conductor, as the answer. Service
Lateral (SL) and Service Drop (SD) were both optimized at a No. 4 conductor (ASL = 41
kcmil).
We then ran the program similarly for the Class 2 residences (Table 4.1) and
obtained the answer as a 50-kVA transformer, with a No. 2/O conductor (ASL = 133.1
kcmil) for SL and a No. 1 conductor (ASL = 83.69 kcmil) for the SD. In both program
runs for Class 1, 2 and 3, the voltage drops were within the specified tolerance limits of 5
percent per component (10 percent total).
When we entered the Class 1 data in the program, TAC equation derivative
answer is a complex value for the transformer (ST). The imaginary part is probably due
to the large maximum load. Long blocks, which will have longer wire lengths, can cause
the voltage drop constraint in the program to be violated earlier. That effect is more
profound when we lower the tolerance level of the voltage constraint to much below 10
percent. Class 1 data in the program run yielded the answer of a 100-kVA transformer, a
No. 300 MCM service lateral (ASL = 300 kcmil), and a No. 3/O conductor (ASL = 167.8
kcmil) for SD.
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In fact, we ran each of the normal Runs with a 50 percent longer length to see
this effect. We did not notice any constraint violations until we increased the lengths to
about twice long and Class 1 with high loading showed constraint violations earlier.
Alternately, one can reduce the tolerance of the voltage drop in the program to see similar
change taking place.
We also wanted to test the sensitivity of the program to the higher electricity
mark-up cost. We have provided 12 runs under high electric mark-up case (twice the
normal value in Runs 13 thru 24).
We have also provided an alternate similar run of each case with lower
capitalization value to see the results. We replaced the capitalization rate (utility rate of
return) to lower (10%) and higher (15%) values to discover program sensitivity to the
solution based on the assumed capitalization rate (ὶ ), as tabulated in the above tables, to
obtain the utility valuation based upon a conservative long-term policy towards higher
capital investment.
Finally, we first executed the program with the original runs at power factor of 90
percent and then we lowered the power factor to 70 percent to compare the results. The
results do not show that lower power factor exacerbates the voltage drop constraint,
which is counter-intuitive to our initial expectations. The reality, however, is that
constant energy loads under lower power factor condition will demand higher current,
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which ultimately result in higher kVA and cause program to choose higher conductor
sizes, consequently. However, we have no way of reflecting that in our simple program
as we input the Table 4.1 column values. We have to increase the loads proportionately to
capture that lowered power factor effect. Higher conductor sizes will undoubtedly affect
cost and cause higher TAC for the utility company.
We also wanted to show the effect of lowering the Voltage Drop constraint. By
setting the constraint to 2.5 percent in SL and SD, and 5 percent overall voltage drop, we
force the Matlab program to choose larger size conductors, as it is shown in the Runs 37
to 48. The TAC equation yields complex solution and it results in out-of-bound answers
for the longer lengths in Class 1 column data. High loading is the main cause of not
reaching solution and ultimately, the designed distribution calls for a revision.
64
Chapter 7
CONCLUSIONS
Optimization of the secondary distribution is a tedious process. It first requires an
understanding and familiarity of the primary and secondary system to identify the
uniqueness (if any) of the system. Based on this layout, demographical expectations and
growth anticipated, the system designer can then derive the cost figure for this Primary
system. In more sophisticated optimization models, the integer programming and
dynamic programming techniques are employed, as they are more appropriate solutions.
However, our assignment was confined with use of simple Matlab programming to
devise a method to optimize the system secondary, and still account for a constraint,
which in this case was the overall voltage drop for the secondary system. We were
destined to prove the point using only Matlab programming technique and capability.
In our program, the dimension of the blocks, and therefore the lots, are parameters
that can be safely changed for sensitivity analysis. The program constraint limit of
voltage drop can also be altered for ease of analysis. We have justified our cost structure
in chapter 6 (Economic Estimation and Analysis), but those cost data may also be
adjusted for fine tuning or sensitivity analysis, as well. Finally, the number of the
transformers and radial feeding configuration can be altered without many great
obstacles. Of course, the optimization program will have to be accordingly revised to
account for the required formulation.
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With the procedures described above the voltage profile, the conductor thermal
capacity, tapering and short-circuit strength and the protective grounding of a radial
secondary power distribution system can be examined. If the results of this examination
are not satisfactory to the system designer, alternative optimizing technical solutions must
be proposed, which concern transformer changes or conductor replacements or both.
These solutions are economically estimated and the most economical one is finally
adopted.
Adjusting for load growth is also challenging for the distribution designers, as it
will pose the predicament for the system designers to be more conservative with their
initial designs and allow higher equipment rating or better specification to fit into the
primary side. Higher protection standards and non-linear nature of many loads cause
equipment to fail prematurely, or heat up and result in shorter life due to harmonics.
Adding to this challenge will be the integration of renewable Distributed Energy
Resources (DER) that will dominate the future distribution grid. Many of these DERs
have solid state inverters that will exacerbate the harmonics effect.
Furthermore, the planned procedures must provide for some degree of the
flexibility from the norm. Electric Cars charging needs, e.g., requires direct upgrade of
the transformers and conductors in some neighborhoods distribution systems, and
therefore, the concept of effective integration is vital because of the charging capability
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of each vehicle. Future distribution system engineers and designers undoubtedly are faced
with great many challenges and game changes, as well.
The loading on the distribution transformers will be significantly increased once the
ownership of Plug-In-Hybrid Electrical Vehicle (PHEV) becomes prevalent in our
modern society and when the average neighborhood displays a significant presence of
these cars. The average electric car will need about 20 to 30 kW-hour of charge for a
round trip of about 60 miles. While that is not a huge load by itself, relative to size of
transformers and wires, it puts undue burden on the grid [14]. One can imagine that while
the early adoption may be low, even only two out of twelve houses owning and charging
these electrical vehicles can seriously burden the neighborhood distribution grid. Finally,
the new utility tariff and rate structure must be provided by the regulators to provide for
the shifting paradigm in the utility industry and its ultimate migration to the Smart grid
domain.
The purpose of this masters project was to demonstrate that (1) the optimization
process is essential between main components of the distribution system, being primary
or secondary and (2) the optimization process can be implemented between the main
components on the basis of fixed initial cost and operating cost of the system, and even a
basic Matlab Program is capable of obtaining solutions to the design problem. Future
Smart grid vision is to develop and deploy a more reliable, secure, economic, efficient,
safe, and environmentally friendly electric system. It will hinge on optimization of
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several sub system to attain that goal. Advanced grid technologies will help attaining that
goal with the increase in grid efficiency and reliability
68
Bayliss, Colin, Transmission and Distribution Electrical Engineering, 2nd Edition, Jordan Hill, Oxford:
APPENDIX A
Matlab Optimization Program for Secondary Distribution System
Instructions for Running the Matlab Optimization Program in Distribution System
The following are instruction steps to utilize the Matlab Optimization program:
1. The program is designed to provide the design parameters to the distribution
designer who will layout the typical urban area City block. It can easily be
modified to use it for bigger acreages available in the agricultural areas as well.
This program is constructed with the idea that configuration of distribution
system greatly affects the outcome as the layout will determine the efficient
means of distribution, and hence, we have assumed a city residential block
typically found in the urban areas of most major U.S cities (typically 960 feet
long by 330 feet wide).
2. Typically, the utility would like to reduce the voltage drop at the end of the line
and hence would bring the distribution high voltage side to the middle of the
circuit so that two almost equal strings can service the two sides of the pattern.
The utility therefore serves the two strings by the two transformers from the
utility Right of Way which service these blocks, by single-phase distribution
circuit of the serving electric utility. We provided the input queries for the
69
dimensions of this block as to the length and width, which will have a bearing
upon the length of service laterals and service drop conductors serving the
neighborhood area. The example in the book has assumed two single-phase
transformers serving this block, and each transformer serving power to twelve
customers (we have assumed 12 kV primary distributions for these transformers,
and 240- volt secondary to customers). [1]
3. The utilities have to justify their cost expenditures to their financial managers
and public agencies involved, as the total expenditures will undoubtedly affect
the tiered electric rates that ratepayers must pay. Therefore, extra prudence is
applied so that the utility is not heavily weighted in the purchase of non-utilized
assets. Of course, different assets have different life spans and that is why the
utility industry has developed the annualized asset cost to have comparison basis
of measuring alternative proposals on an equal footing. When the assets are
compared on the basis of their amortized life, it will simplify the job of planning
managers to develop the consensus for funding the suitable alternatives.
4. The optimized equations in the program are derived from the absolute
maximized or minimized equations to provide the optimal value for the
variables. However, the standard sizes available in the commercial market do
not render themselves to exact sizes. It is pertinent for a distribution system
designer to obtain a standard size that can still provide near optimal value to the
70
utility, minimizing the Total Annualized Cost (TAC) that service utility must
burden with.
5. The average load a house may use may greatly depend on the neighborhood
demography and its location. Over the past century electricity consumption has
increased substantially per capita, mainly due to exponential use of automation in
human life in the developed world, while it provides the advances in quality of
life. Interestingly, while the utilities seek to dampen the peak power usage to
curtail high cost of their spot generation, they have to design their distribution
conservatively to accommodate the perceived peak load, even though this
equipment may not be fully utilized a great portion of the time. Hence, sizing
their equipment for average load is allowed, which is somewhat diversified by
the local authorities having jurisdictions. The average household load is also
provided thru an input to the program, as different type of residential areas may
vary in their demography and their electrical usage. The program calculates the
load, sizes the next commercially available transformer, and provides the
appropriate sizes for the Service Lateral (SL) and Service Drop (SD) conductors.
It then calculates the TAC.
6. Two files are attached with this instruction sheet. One is the Matlab program
called OptimizeTAC.m and the other is the Excel input data called
TransfDataTryVD24.xls. You would need to save the TransfDataTryVD24.xls in
71
the folder that Matlab works with to be able to import the table values
automatically into Matlab.
72
Matlab Optimization Program in Distribution System
%This program evaluates the distribution circuit requirements for a
block %development and then determines the transformers' size, Service
Laterals, %and Service Drops. Block length and widths are inputs given
to the program %as specifications as well as the residential load,
voltage and power factor. clear all clc
foadfile1='TransfDataTryVD24.xls'; %reads data from the first
worksheet in sheet=1; %the Excel spreadsheet file named 'foadfile1' and returns
the x1range='B10:N17'; % numeric data in array num. subsetA=xlsread(foadfile1,sheet,x1range); A=subsetA;
foadfile2='TransfDataTryVD24.xls'; %reads data from the second
worksheet in sheet=2; %the Excel spreadsheet file named 'foadfile2' and returns
the x2range='B10:N22'; % numeric data in array num. subsetB=xlsread(foadfile2,sheet,x2range); B=subsetB;
Lab=input('Enter the spacing for block length Lab in ft: '); Wac=input('Enter the spacing for block width Wab in ft: '); volt=input('Enter the secondary distribution voltage: '); prompt1 = 'What is Max Average Load for each of 12 customers in KVA? '; La12=input (prompt1); prompt2= 'What is the Load for 4 customers in KVA ? '; L4=input (prompt2); prompt3 = 'What is Max Load for 1 customer in KVA? '; L1=input (prompt3); pf=input('Enter the distribution system power factor (pf)cos(Phi): '); %Lab=1*960;Wac=1*330;volt=240;La12=4.4;L4=6;L1=10;pf=0.9; i=0.15; % The utility cost annualized Rate (Capitalization Rate) ICCAP=15;ICsys=8*350;Iexc=0.015;FLD=0.35;ECoff=.015;ECon=.02; % Defining the parameters; XX=2; % No of Transformers YY=12; % No of Customers poles=6; % No. of Poles LotW=Lab/12; % Lot Width LotL=Wac/2; % Lot Length LSL=4*LotW; % Length of SL LSD=0.5*LotL; % Length of SD phi=acos(pf); % Phi Angle (phi) Smin=YY*1.1; % In kVA Aload=YY*La12; if Aload<Smin ST=Smin;ASL=41.74;ASD=26.24;
C01=XX*8*(250+7.26*ST0)*i;% $/Block-2 trx per block & 12 services per
ea. trx C02=XX*8*(60+4.5*ASL0)*i*2*(LSL/1000); %Triplex aluminum cable cost for
Service Lateral per transformer C03=XX*8*(60+4.5*ASD0)*i*YY*LSD/1000; % Service Drop initial cost
($/block) C04=8*160*poles*i; % Cost of Poles $/ block C05=2*Iexc*ST0*ICCAP*i; % Capacitors’cost for System energizing & I
excitation C06=2*(ICsys*i+8760*ECoff)*0.004*ST0; % Cost of iron losses/ upleg of
Secondary ($/ block) FLS=0.3*FLD+0.7*FLD^2; Smax=YY*La12; % This is found from Table 6.4 for 12 class 2 customers,
per book example PTcu=(0.073+0.00905*ST0);% Transformer copper losses Where 15
kVA<=ST<=100 kVA % This is found from (Eq. 6.10) C07=XX*(ICsys*i+8760*ECon*FLS)*(PTcu)*(Smax/ST0)^2; %From Eq.6.9, The annual OC of tx copper losses per
if VDSD2<5 break else ASD3=B(j,12);SD1=B(j,2);XSL=B(j,5);RSL=B(j,3); if VDSL3<5 ASD2=ASD3; VDSD2=VDSD3;
else ASD3=B(j+1,12);SD1=B(j+1,2);XSL=B(j+1,5);RSL=B(j+1,3); end end end VDSD=VDSD2;
C1=XX*8*(250+7.26*ST)*i;
% $/Block-2 trx per block & 12 services per ea. trx C2=XX*8*(60+4.5*ASL)*i*2*(LSL/1000); %Triplex aluminum cable cost for
Service Lateral per transformer C3=XX*8*(60+4.5*ASD)*i*YY*LSD/1000; % Service Drop initial cost
($/block) C4=8*160*poles*i; % Cost of Poles $/ block C5=2*Iexc*ST*ICCAP*i; % Capacitors’cost for System energizing & I
excitation C6=2*(ICsys*i+8760*ECoff)*0.004*ST; % Cost of iron losses/ upleg of
Secondary ($/ block) FLS=0.3*FLD+0.7*FLD^2; Smax=YY*La12; % This is found from Table 6.4 for 12 class 2 customers,
per book example
78
PTcu=(0.073+0.00905*ST);% Transformer copper losses Where 15
kVA<=ST<=100 kVA % This is found from (Eq. 6.10) C7=XX*(ICsys*i+8760*ECon*FLS)*(PTcu)*(Smax/ST)^2; %From Eq.6.9, The annual OC of tx copper losses per block RSL=(20.5*(LSL)*2)/(1000*ASL); % RSL=p*L/1000*ASL (Ohm.kcmil/trx.) PSLcu=(((4*L4*1000)/(volt))^2)*(RSL/1000);
%PSLcu=((4*L4/volt)^2)*(12.3/ASL0)/1000; C8=XX*(ICsys*i+8760*ECon*FLS)*PSLcu; % From Eq. 6.11, annual OC of copper losses in the 4 SLs RSD=(20.5*LSD*24*2)/(1000*ASD); %Rc=p*(LSD/1000)*ASD0=68.88/ASD
PSDcu=((Lmax/volt)^2)*(68.88/ASD)*1/1000; C9=(ICsys*i+8760*ECon*FLS)*PSDcu; % From Eq. 6.11, annual OC of copper
losses in 24 SDs)
TAC2=C1+C2+C3+C4+C5+C6+C7+C8+C9; disp(' “Value of TAC2 “'); disp(TAC2);
% The Voltage Drop Constraint is tested on the obtained values % VoltDrop = VDT+VDSL+VDSD; %Zpu=0.02; %Zbase=voltage^2/ST;%Zpu is given in input tables %ZVST=Zpu*Zbase; VDT=1000*(Aload/(volt)^2)*XT*100; % VDT=12*LoadC*ZVST;
VoltDrop=VDT+VDSL+VDSD;
if VoltDrop>10 % The Voltage Drop Constraint is tested for Optimization
disp('"Voltage Drop Too High! -- Provide a different design."'); disp('"VoltDrop in % = "'); disp(VoltDrop); disp(VDT); disp(VDSL); disp(VDSD) disp(TAC2); disp(' “Size of transformer in kVA is = ”');disp(ST); disp(' “Size of ASL “’');disp(ASL2);disp(AMP); disp(' “Size of ASD “');disp(ASD2);disp(SD1); else disp('"VoltDrop in % = "'); disp(VoltDrop);disp(VDT);disp(VDSL);disp(VDSD) disp(TAC2);%disp(ST);disp(ASL);disp(AMP),disp(ASD);disp(SD1); disp(' “Size of transformer in kVA is = ”');disp(ST); disp(' “Size of ASL “’');disp(ASL2);disp(AMP); disp(' “Size of ASD “');disp(ASD2);disp(SD1);
end
79
APPENDIX B
Instructions for Matlab TAC Program in Distribution System
The following are instruction steps to utilize the Matlab TAC program:
1. This program is constructed with the idea that configuration of distribution system
greatly affects the outcome as the layout will determine the efficient means of
distribution, and hence, we have assumed a city residential block typically found
in the urban areas of most major U.S cities.
2. Typically, two transformers from the utility Right of Way serve these blocks,
usually by single-phase distribution circuit of the serving electric utility. We
assume the secondary distribution system within a City block, as discussed in
Appendix A. The block dimensions are according to Figure 4.4 Similar to
previous program, it queries for the inputs of Transformer size in KVA, Cable
sizes (ASL and ASD) in kcmil, and loads (L1, L4, and La12) in KVA . Values for
loads L1, L4, and La12 can be obtained from Table 4.1, or can be any
combination of average household load for one (maximum load), four, or 12
customers. Similar to the example in the book, we have assumed 12 kV primary
distributions for these transformers, and 240- volt secondary to customers. As
before, two single-phase transformers are serving this block, and each transformer
serving power to twelve customers [1].
80
3. The following questions will be asked when program is run:
What is ST in kVA?
What is ASL in kcmil?
What is ASD in kcmil?
What is the load for 12 customers in kVA?
What is the load for 4 customer in kVA?
What is Max load (1 customer) in kVA?
Then TAC will be calculated by the program in $/block.
round(TAC); TAC=ans % TAC is calculated by program
83
APPENDIX C
Secondary Distribution System Voltage Drop Program
Instructions for Running the Matlab Voltage Drop Calculation Program
The following are instruction steps to utilize the Matlab Voltage Drop Program :
1. The program is designed to provide the design parameters to the secondary
distribution system designer who has the layout of the typical urban Area City
block, found in the urban areas of most major U.S cities (typically 960 feet long
by 330 feet wide).
2. It may also be modified to use it for bigger acreages available in the agricultural
areas, or as a calculator on the primary system. This program calculates the
voltage drop within the Transformer, Service Lateral (SL), and Service Drop
(SD).
3. The utility would reduce the voltage drop at the end of the line by bringing the
distribution high voltage side to the middle of the circuit, so that two almost
equal strings can service the two sides of the pattern. The utility therefore serves
the two strings by the two transformers from the utility Right of Way which
service these blocks, by single-phase distribution circuit of the serving electric
utility. We provided the input queries for the dimensions of this block as to the
84
length and width, which will have a bearing upon the length of service laterals
and service drop conductors serving the neighborhood area. The example in the
book has assumed two single-phase transformers serving this block, and each
transformer serving power to twelve customers (we have assumed 12 kV primary
distributions for these transformers, and 240- volt secondary to customers) [1].
4. The utilities have technical designers who are responsible to keep voltage drop
within a tolerance level and at the same time must justify their cost expenditures
to their financial managers and public agencies involved, as the total
expenditures will undoubtedly affect the tiered electric rates that ratepayers must
pay. Therefore, extra prudence is applied so that the utility is not heavily
weighted in the purchase of non-utilized assets
5. The load is queried into this program as energy use of a house may greatly
depend on the neighborhood demography and its location. The program queries
for the single family load, diversified loads, and it then calculates the voltage
drops values at the Transformer (ST), Service Lateral (SL) and Service Drop
(SD) conductors. It then calculates the Total Voltage Drop for all three in the
secondary system.
85
6. Two files are attached with this instruction sheet. One is the Matlab program
called VoltageDrop.m and the other is the Excel input data called
TransfDataTryVD24.xls.
User needs to save the TransfDataTryVD24.xls in the folder that Matlab works
with to be able to import the table values automatically into Matlab.
86
Matlab Program for Voltage Drop in Distribution System
%This program evaluates the distribution circuit voltage drop
requirements for a block %development and then determines if the
constraint threshold is exceeded, based on the transformers' size,
Service Laterals, %and Service Drops. Block length and widths are
inputs given to the program %as specifications as well as the
residential load, voltage and power factor.
clear all clc
foadfile1='TransfDataTryVD24.xls'; %reads data from first worksheet in sheet=1; %the Excel spreadsheet file named 'foadfile1' and returns the x1range='B10:N17'; % numeric data in array num. subsetA=xlsread(foadfile1,sheet,x1range); %disp(subsetA) A=subsetA;
foadfile2='TransfDataTryVD24.xls'; %reads data from the second
worksheet in sheet=2; %the Excel spreadsheet file named 'foadfile2' and returns the x2range='B10:N22'; % numeric data in array num. subsetB=xlsread(foadfile2,sheet,x2range); %disp(subsetB) B=subsetB; Lab=input('Enter the spacing for block length Lab in ft: '); Wac=input('Enter the spacing for block width Wab in ft: '); volt=input('Enter the secondary distribution voltage: '); prompt1 = 'What is Max Average Load for each of 12 customers in KVA? '; La12=input (prompt1); prompt2= 'What is the Load for 4 customers in KVA? '; L4=input (prompt2); prompt3 = 'What is Max Load for 1 customer in KVA? '; L1=input (prompt3); ST1=input('Enter the distribution system Transformer Size: '); pf=input('Enter the distribution system power factor (pf)cos(Phi): '); ASL1=input('What is the cross section of SL Line? : '); %AMP=input('What is the ampacity of SL Line? : '); ASD1=input('What is the Cross section size of SD Line? : '); %ASD=input('What is the length of SD Line? : ');
%Lab=1*960;Wac=1*330;volt=240;La12=10;L4=12;L1=18;pf=0.9; %ST1=75;ASL1=74;ASD1=43; i=0.1; % The utility cost annualized Rate (Capitalization Rate) ICCAP=15;ICsys=8*350;Iexc=0.015;FLD=0.35;ECoff=.015;ECon=.02; % Defining the parameters; XX=2; % No of Transformers YY=12; % No of Customers poles=6; % No. of Poles LotW=Lab/12; % Lot Width LotL=Wac/2; % Lot Length
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LSL=4*LotW; % Length of SL LSD=0.5*LotL; % Length of SD phi=acos(pf); % Phi Angle (phi) Smin=YY*1.1; % In kVA Aload=YY*La12; if Aload<Smin ST=Smin;ASL=41.74;ASD=26.24; else
end %ASL=B(k,12);AMP=B(k,2);XSL=B(k,5);RSL=B(k,3); if ASL1<=B(1,12) % Service Lateral Ampacity (SL) Selection Logic ASL=B(1,12);AMP=B(1,2);XSL=B(1,5);RSL=B(1,3); disp(ASL);disp(AMP);
if VDSD2<5 break else ASD3=B(j,12);SD1=B(j,2);XSL=B(j,5);RSL=B(j,3); if VDSL3<5 ASD2=ASD3;
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VDSD2=VDSD3;
else ASD3=B(j+1,12);SD1=B(j+1,2);XSL=B(j+1,5);RSL=B(j+1,3); end end end VDSD=VDSD2; % The Voltage Drop Constraint is tested on the obtained values % VoltDrop = VDT+VDSL+VDSD; %Zpu=0.02; %Zbase=voltage^2/ST;%Zpu is given in input tables %ZVST=Zpu*Zbase; VDT=1000*(Aload/(volt)^2)*XT*100; % VDT=12*LoadC*ZVST; %VDSD=1000*(L1/(volt)^2)*2*(LSD/1000*((RSD*cos(phi))+XSD*sin(phi)))*100
; VoltDrop=VDT+VDSL+VDSD;
if VoltDrop>20 % The Voltage Drop Constraint is tested for Optimization disp('"Voltage Drop Too High! -- Provide a different design."'); disp('" VoltDrop in % = "'); disp(VoltDrop);disp(VDT);disp(VDSL);disp(VDSD); disp(' “Size of transformer in kVA is = ”');disp(ST); disp(' “Size of ASL “');disp(ASL2);disp(AMP); disp(' “Size of ASD “');disp(ASD2);disp(SD1); else disp('"VoltDrop in % = "'); disp(VoltDrop);disp(VDT);disp(VDSL);disp(VDSD); disp(' “Size of transformer in kVA is = ”');disp(ST); disp(' “Size of ASL “');disp(ASL2);disp(AMP); disp(' “Size of ASD “');disp(ASD2);disp(SD1); end
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APPENDIX D
Distribution System Component Information Background
Conductors
For utility companies one of the most expensive components is the conductors.
Due to this fact, it is imperative that distribution system engineer and planner choose the
most appropriate conductor type and size so that optimum operating efficiency can be
realized[38][39]. The designer must come up with best price for a conductor with best
conductivity-to-weight ratio and/or strength -to-weight ratio. For necessary ratio designer
needs to look at all the factors such as voltage stability of the line, loading of the line,
losses of the line, tension load, and environmental factors [40].
For selecting a conductor, technical and financial criteria need to be considered.
Not only maximum power transfer, minimum loss and thermal capacity , per the system
design specification, but also the price should be take in to account. While choosing a
new conductor that has to match or work the existing conductor in the network, it has to
be suitable for environmental conditions, as well.
Most common conductor materials are Aluminum and copper. Copper is the best
conductor and is the base-line reference for conductivity characteristics. On the other
hand, the closest alternative for conductivity is Aluminum with less weight. Aluminum
conductivity is 61 percent, its weight is 30 percent, and its breaking strength is 43 percent
of copper [16].
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Because of the breaking strength of aluminum, aluminum conductor is made with
strands of high-strength steel in their central core, and the combination is called
Aluminum Cable Steel Reinforced or ACSR. ACSR is lighter than copper and has
strength and conductivity of copper. At the same time, ACSR has longer life span and it
last much longer than conductor usual 40 years. Following figure shows various