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EEE577: Term Project




                                                                    11/10/2011




                       EEE577: Term Project
   STUDY OF TRANSMISSION ADEQUACY BY ARIZONA
    TRANSMISSION EXPANSION CO. FOR ADDING PV
                   RESOURCES


                             A PROJECT REPORT


                                 Submitted by
                               Supriya Chathadi


              In partial fulfillment for completion of the course
              EEE577: Power Engineering Operations/Planning


                                      at


                        Arizona State University, Tempe




[Type text]                                                              Page 1
EEE577: Term Project




Table of Contents

1. Introduction ......................................................................................................................................... 3
2. The Per Unit System ........................................................................................................................... 3
   2.1. Advantages................................................................................................................................... 3
3. DC Power Flow................................................................................................................................... 4
   3.1. Assumptions................................................................................................................................. 4
   3.2. Formulation .................................................................................................................................. 4
4. Actual Power Flows in the System ..................................................................................................... 5
   4.1. Bus Terminology ......................................................................................................................... 5
   4.2. Initial Calculations ....................................................................................................................... 5
   4.3. Power Flow Calculations ............................................................................................................. 5
5. PV Injection ........................................................................................................................................ 6
   5.1. Maximization using linprog ......................................................................................................... 6
6. Line Outage Contingencies ................................................................................................................. 6
7. Results ................................................................................................................................................. 7
8. Additional Concerns ........................................................................................................................... 8
9. Conclusion .......................................................................................................................................... 9
10. References ......................................................................................................................................... 9



Appendix 1: System Representation ........................................................................................................ i
Appendix 2: MATLAB Codes ................................................................................................................ ii
   A2.1. Base Case: All Lines under Operation ...................................................................................... ii
   A2.2. Line Outage Contingency between Flagstaff & Four Corners .................................................. ii
   A2.3. Line Outage Contingency between Flagstaff & Palo Verde .................................................... iii
   A2.4. Line Outage Contingency between Flagstaff & Blythe ........................................................... iii
   A2.5. Line Outage Contingency between Blythe & Imperial Valley ................................................ iv
   A2.6. Line Outage Contingency at One of the Lines between Imperial Valley and Palo Verde ........ v
   A2.7. Line Outage Contingency between Palo Verde & Bicknell ...................................................... v




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1. Introduction

A study is performed by Arizona Transmission Expansion Co. (AZTEx) to obtain the transmission
adequacies at certain parts of Arizona on adding high level solar PV resources at suggested sites.

       This report is based on the study where PV resources are added at Bicknell and Blythe.
       The excess generation due to PV injection is dissipated at Imperial Valley and Blythe in
        proportion to their present load levels.

An approximate representation of the system base loads and generation, suggested PV injections and
the compensating loads are shown in Appendix 1.


2. The Per Unit System

It is a common practice in power system studies to represent all system parameters as a ratio of a
defined base quantity in the same units, called the per unit representation.

                                                 Quantity (Actual units)
                         Per Unit Quantity =
                                               Base Quantity (Actual units)

Generally, the bases for any two of the system parameters is defined (SB and VB, SB and IB, etc.) are
defined from which all other bases are calculated. For example, when SB and VB are given, the
following expressions can give other base quantities.

                                               SB 3         SB
                                       IB =            =
                                              VB   3       VB 3

                                              (VB/ 3 ) 2   VB 2
                                       ZB =              =
                                                SB 3       SB

                                                       1
                                                YB =
                                                       ZB

2.1. Advantages

       Per unit quantities for similar components (generators, transformers, lines) will lie within a
        narrow range, regardless of their ratings and sizes.
       They are the same on either side of a transformer, independent of voltage level.
       The relative values of circuit quantities are clearly identified as unnecessary scaling factors
        are eliminated.
       Use of the constant       is reduced in three-phase calculations.
       Much simpler for calculations and ideal for computer simulations as well.
       It rules out the problem of using different units in different parts of the world by introducing a
        universal standard.




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3. DC Power Flow

There are a number of ways to perform power flow studies in a system. The simplest formulation is
called „DC Power Flow‟. The name is illusive because there is nothing to do with DC in it.

Some important observations are made from actual load flow studies and few assumptions are made
in order to simplify the calculations and still not vary the results in a large scale.

3.1. Assumptions

        The transmission lines are assumed to be purely inductive as the resistances are much smaller
         than the reactances.
        As all machines operate in synchronism, the differences in angles between their voltage
         phasors are typically very small (less than 30◦). Thus it is assumed that sin δ ≈ δ.
        It is seen that the per unit voltages operate close enough to 1p.u. This comes up with an
         assumption that the voltage magnitudes can be set to 1p.u. at all buses.
        As reactive power flow between two buses is dependent on the difference in their voltage
         magnitudes, an assumption can be made that there is no reactive power flow in the system.
        The real power supplied by a bus is much greater than the reactive power supplied and hence
         reactive power injection is neglected.

3.2. Formulation

The actual real power flow is given by the equation:

                                                Vi Vj sin ij
                                        Pij 
                                                          xij

Based on the assumptions, the power flow equation can be written as:

                                                ij       i  j
                                        Pij          
                                                xij             xij

The power flow matrix for a system can be written from the above expression as follows:

                                          Pbus  Bbusδ bus
where,

Bbus is called the susceptance matrix, given by the imaginary part of the admittance matrix (Ybus)

                                                   Y 11          Y 12      ...   Y1n 
                                                   Y 21          Y 22      ...   Y 2 n
                        Bbus  imag(Y bus)  imag                                     
                                                   ...               ...   ...    ... 
                                                                                      
                                                   Yn 1          Yn 2      ...   Ynn 

                                        Yii = yi0+yi1+yi2+…+yin

                                             Yij = Yji = -yij




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where, yij is the primitive admittance between buses i and j, given by 1
                                                                           xij


4. Actual Power Flows in the System
4.1. Bus Terminology

For ease of calculation, the buses are numbered from 0 to 5, where 0 indicates the reference bus. The
following conventions are used in the following sections:

                                         Palo Verde (P) – 0 (ref)
                                         Four Corners (FC) – 1
                                            Flagstaff (F) – 2
                                             Blythe (BL) – 3
                                         Imperial Valley (I) – 4
                                            Bicknell (BI) – 5

4.2. Initial Calculations

The reactance of each line can be calculated as the product of reactance per km of the conductor used
and the length of the line. The double line is considered as reactances in parallel.

The base and per unit values for all the line are also calculated and tabulated as follows:

                                     Table 1: Impedance Calculations

                                                  SB = 100 MVA = 100MW (no reactive power flows)
         Reactance (ohms)                  Base Reactance (ohms)      Per Unit Reactance (p.u)
x12      204 x 0.2908j = 59.2008j          3452/100 = 1190.25         59.2008j/1190.25
x20      80 x 0.0496j = 3.968j             3452/100 = 1190.25         3.968j/1190.25
                                              2
x23      98 x 0.5464j = 53.5472j           345 /100 = 1190.25         53.5472j /1190.25
x34      110 x 0.5464j = 60.104j           3452/100 = 1190.25         60.104j /1190.25
x40      (357 x 0.056j)/2 = 9.996j         5002/100 = 2500            9.996j /2500
                                              2
x50      41 x 0.2903j = 11.8982j           345 /100 = 1190.25         11.8982j /1190.25


4.3. Power Flow Calculations

The values of δ for all buses are found from the expression, δ bus  Bbus Pbus where, Pbus is a
                                                                                 1


matrix showing power injection at various buses. They are given with reference to Palo Verde as
shown below:

                                             δP       0.0000
                                             δFC     -0.3382
                                             δF       0.0100
                                             δBL      0.1000
                                             δI       0.1000
                                             δBI     -0.0800

Power flows in the lines are found out by increasing the dimension of δbus by adding a zero for the
reference bus, and using the same formula. But, this time the rows of Bbus have entries only at two
sites between which the power flow is calculated.


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Consolidated results are shown in section 7.


5. PV Injection

It is desired to inject maximum PV resources at Blythe and Bicknell without overloading any of the
lines (considering the long term rating). The power injection is compensated at Imperial Valley and
Blythe in proportion to their present loads. Thus, their participation factors are calculated as:

                                                 25
                                         PFI =          0.926
                                               25  2
                                                  2
                                        PFBL =           0.074
                                                25  2

If the power injected at Blythe P1 and that at Bicknell is P2, they are compensated as 0.926(P1+P2) at
Imperial Valley and 0.074(P1+P2) at Blythe.

Same calculations as done in section 4 are done to obtain power flows in terms of P1 and P2.
Optimal values for P1 and P2 are found using linear programming (linprog) in MATLAB. The codes
are shown in Appendix 2.

5.1. Maximization using linprog

Linear programming is defined as:

                                           Min f(x), subject to
                                           Ax ≤ b; Aeqx = beq
                                              lb ≤ x ≤ ub

where, f is called the objective function, x is a vector consisting of decision variables, Ax ≤ b are the
inequality constraints, Aeqx = beq are the equality constraints, lb and ub are the limits for the decision
variables.

The objective in this case is to maximize P1 and P2, with the line flows not exceeding their limits.
The problem can be formulated as given below:

                                     Max (P1+P2) = -Min (-P1-P2)
                                       line flows ≤ line ratings
                                            0 ≤ P1, P2 ≤ ∞

In the constraints, the line flows can be in either direction, thus they might change signs in some
cases. As the direction of line flows cannot be predicted sometimes, it might be necessary to manually
change the signs for the line flows in order to maximize the PV injection. The resulting values of P1
and P2 are the maximum amounts of power which can be injected in terms of PV resources at Blythe
and Bicknell. Results are tabulated in section 7.


6. Line Outage Contingencies

This section deals with the study of (N-1) line outage contingencies. The procedure is basically the
same as illustrated with all lines under operation, except that the results are going to slightly different
because of the difference in Ybus.


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On removing the lines one after another, it is seen that the power generations may not suffice the
loads in some cases such as a line outage between Four Corners and Flagstaff or between Palo Verde
and Bicknell, as the generation in Four Corners or Bicknell would be lost. In such cases, it is assumed
that Palo Verde supplies the power loss due to line outage, for the power flows to converge. This is
based on the given suggestion that equivalent generation could be added to another existing
generation site.

The power flow and maximum PV injection results are tabulated in Section 7. It is seen that a
contingency in one of the lines or both between Palo Verde and Imperial Valley is not allowed as the
lines overload even for the base case generation and loads. Thus the study of PV injection cannot be
done for this case.


7. Results

Table 2 gives the line flows in all the lines for including and not including PV injection. For the case
on injecting PV resources, the highlighted values indicate the line which might start overloading if
little more PV resources are added to the system. It is seen that for a line outage between Palo Verde
and Imperial Valley, line overloading occurs even without injecting PV resources.

             Table 2: Per Unit Power Flows in All Lines for with/without PV Injection
  Per Unit Power        PFC-F         PP-F           PF-BL           PI-BL            PP-I                            PBI-P
      Flows
 (SB = 100MVA)
    Condition         No    With No PV     With  No PV    With   No PV    With    No    With PV               No          With
                       PV    PV               PV                PV                PV       PV                 PV          PV
   Line ratings                                                                           15+15
                      7.09   7.09    14.8     14.8     4.99     4.99     4.99     4.99     =30        30      10              10
  With all lines
                        7     7       3      1.8010     2      2.8010   0.0002   4.9897     25      29.9998       8      8.1988
 under operation
 With line outage
                        -     -     9.773    5.1902   1.773    2.8098   0.2271   4.5358   25.23       30          8      8.1872
between Flagstaff
 & Four Corners
 With line outage
                        7     7       -        -        1        1        3      1.0100     28        30          8           10
between Flagstaff
  & Palo Verde
 With line outage
                        7     7       1        1        -        -        2      0.9900     27        29          8           10
between Flagstaff
    & Blythe
 With line outage
                        7     7       3      1.3551     2      2.3551     -        -        25        30          8      8.6449
between Blythe &
 Imperial Valley
With line outage at
                                                                                          24.064
 one of the lines       7     -     3.9357     -      2.9357     -      0.9357     -      (rating      -          8           -
between Imperial                                                                          in this
 Valley and Palo                                                                          case is
                                                                                            15)
      Verde
 With line outage
                        7     7       3      1.8162     2      2.8162   0.0002   4.9897     25      29.8162       -           -
  between Palo
Verde & Bicknell

Table 3 summarizes the maximum amount of PV resources which can be injected at Bicknell and
Blythe for different cases. The study of injecting PV into the system is not possible when a line outage
occurs between Imperial Valley and Palo Verde because of overloading, as shown in Table 2.


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Maximum PV can be injected in the system when all lines are under operation, which is about
1078.79 MW.

           Table 3: Consolidated Results for Maximum PV Injection at Blythe and Bicknell
                                   Maximum PV            Maximum PV            Total PV Injection
                                 Injection at Blythe  Injection at Bicknell          (MW)
                                        (MW)                  (MW)
With all lines under operation        1058.91                 19.88                 1078.79
   With line outage between           1010.75                 18.72                 1029.47
   Flagstaff & Four Corners
   With line outage between            230.89                200.00                  430.89
    Flagstaff & Palo Verde
   With line outage between            338.88                200.00                  538.88
      Flagstaff & Blythe
   With line outage between            475.46                 64.49                  539.96
   Blythe & Imperial Valley
With line outage at one of the
lines between Imperial Valley              -                    -                       -
        and Palo Verde
   With line outage between           1058.96                   -                   1058.96
    Palo Verde & Bicknell


8. Additional Concerns

    One of the assumptions of DC load flow studies is to consider that the voltage magnitudes at
     all buses are 1 p.u. This comes up with a conclusion that there will be no reactive power flows
     between any two buses, as difference in voltage magnitudes between them is zero. Thus
     inclusion of reactive power flows, voltage magnitudes, their limits and constraints are all
     inter-related. Including reactive power flows or voltage magnitudes automatically gives rise
     to the other. The study will become more complex and detailed on doing it. The power flow
     equations in this case would be the following:

                                                  Vi Vj ij
                                         Pij 
                                                      xij

                                                Vi ( Vi  Vj )
                                       Qij 
                                                     xij

       The above equations still assume the following:

              The transmission lines are purely inductive.
              δ is very small and hence, sin δ ≈ δ.
              There is no reactive power injection at any bus.

    The active power flow „west of river‟ for the base case is almost negligible. It is 0.0001717
     p.u., from Imperial Valley to Blythe. But with PV injection, it is nearly the rating of the line
     (4.9897 p.u.). The „worst‟ single line outage is the outage of a line between Imperial Valley
     and Palo Verde as one of the lines start overloading for the base case itself. The maximum
     active power flow in the line is 0.9357 p.u.




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    If it is possible to add another transmission line, it is logical to add a line between Flagstaff
     and Imperial Valley. A large amount of power produced by Palo Verde and Bicknell could
     not be transmitted efficiently because of the relatively lower ratings on the lines between
     Flagstaff and Blythe, Blythe and Imperial Valley. A major share of the system load occurs at
     Imperial Valley, thus the transmission lines connecting to it must have compatible ratings. If a
     transmission line made of type (3) conductor is added between Flagstaff and Imperial Valley,
     a transmission path of Palo Verde to Flagstaff to Imperial Valley would be chosen for
     effective transmission of the generated power. Yet another option is to add one more line
     between Imperial Valley and Palo Verde, if it is not required to supply more loads
     anywhere else.


9. Conclusion

      It is seen that the maximum PV injection is possible when all lines are in service, and it can
       be further improved by adding more transmission lines.
      It is seen that the system is not properly designed for an N-1 line outage contingency, and
       thus has to be improved


10. References

   [1] John J. Grainger, William D. Stevenson, “Power System Analysis”, Tata McGraw-Hill
       Publications, January 1994.

   [2] Anomynous, “The Power Flow Equations”, available at:
                        class.ece.iastate.edu/ee458/PowerFlowEquations.doc

   [3] Wikipedia, notes appearing on the subject of per-unit systems, available at:
                                 en.wikipedia.org/wiki/Per-unit_system




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                            Appendix 1: System Representation




                                                                                                         7 p.u.

                                Four Corners (2)


                                                   8 p.u.                                        Flagstaff (1)
          0.074(P1+P2) p.u.


                2 p.u.          Blythe (3)

                                     P1 p.u.

0.926(P1+P2) p.u.                                                        20 p.u.




               Imperial Valley (4)                   Palo Verde (0)                  8 p.u.
    25 p.u.

                                                                  Bicknell (5)

                                                                                             P2 p.u.



                                                            Legend

                                                                      Generation/Load Site

                                                                      Transmission Line

                                                                      Base Case Generation/Load

                                                                      PV Injection/Load Compensation




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                                Appendix 2: MATLAB Codes
A2.1. Base Case: All Lines under Operation

P=[7;-8;-2;-25;8];
Y=[1190.25/59.2008i -1190.25/59.2008i 0 0 0;
-1190.25/59.2008i (1190.25/3.968i)+(1190.25/59.2008i)+(1190.25/53.5472i) -1190.25/53.5472i 0 0;
0 -1190.25/53.5472i (1190.25/53.5472i)+(1190.25/60.104i) -1190.25/60.104i 0;
0 0 -1190.25/60.104i (1190.25/60.104i)+(1/(3.9984i*10^-3)) 0;
0 0 0 0 1190.25/11.8982i];
B=imag(Y);
del=inv(B)*P;
del1=[del;0];
BB=[-20.1053 20.1053 0 0 0 0;
0 299.9622 0 0 0 -299.9622;
0 -22.2281 22.2281 0 0 0;
0 0 -19.8032 19.8032 0 0;
0 0 0 250.10004 0 -250.10004;
0 0 0 0 -100.0361 100.0361];
PP=BB*del1;
syms P1;
syms P2;
Ppv=[7;-8;P1-2-0.074*(P1+P2);-25-0.926*(P1+P2);8+P2];
delpv=inv(B)*Ppv;
del1pv=[delpv;0];
PPpv=BB*del1pv;
a=vpa(PPpv,4);
disp(a);

A=[-3.532*10^(-18) 8.272*10^(-19);
   -0.4548 0.07523;
   -0.4548 0.07523;
   0.4712 0.001232;
    0.4548 0.9248;
    0 1];
b=[7.09-7.0;14.8-2.9998;4.99-1.9998;4.99-0.0001717;30-25.0002;10-8];
f=[-1;-1];
lb=[0;0];
[x,fval,exitflag]=linprog(f,A,b,[],[],lb);
if exitflag==1
   disp(x);
end

A2.2. Line Outage Contingency between Flagstaff & Four Corners
P=[-8;-2;-25;8];
Y=[(1190.25/3.968i)+(1190.25/53.5472i) -1190.25/53.5472i 0 0;
-1190.25/53.5472i (1190.25/53.5472i)+(1190.25/60.104i) -1190.25/60.104i 0;
0 -1190.25/60.104i (1190.25/60.104i)+(1/(3.9984i*10^-3)) 0;
0 0 0 1190.25/11.8982i];
B=imag(Y);
del=inv(B)*P;
del1=[del;0];
BB=[299.9622 0 0 0 -299.9622;
-22.2281 22.2281 0 0 0;
0 -19.8032 19.8032 0 0;
0 0 250.10004 0 -250.10004;
0 0 0 -100.0361 100.0361];



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PP=BB*del1;
syms P1;
syms P2;
Ppv=[-8;P1-2-0.074*(P1+P2);-25-0.926*(P1+P2);8+P2];
delpv=inv(B)*Ppv;
del1pv=[delpv;0];
PPpv=BB*del1pv;
a=vpa(PPpv,4);
disp(a);

A=[-0.4548 0.07523;-0.4548 0.07523;0.4712 0.001232;0.4548 0.9248;0 1];
b=[14.8-9.773;4.99-1.773;4.99-0.2271;30-25.23;10-8];
f=[-1;-1];
lb=[0;0];
[x,fval,exitflag]=linprog(f,A,b,[],[],lb);
if exitflag==1
   disp(x);
end

A2.3. Line Outage Contingency between Flagstaff & Palo Verde

P=[7;-8;-2;-25;8];
Y=[1190.25/59.2008i -1190.25/59.2008i 0 0 0;
-1190.25/59.2008i (1190.25/59.2008i)+(1190.25/53.5472i) -1190.25/53.5472i 0 0;
0 -1190.25/53.5472i (1190.25/53.5472i)+(1190.25/60.104i) -1190.25/60.104i 0;
0 0 -1190.25/60.104i (1190.25/60.104i)+(1/(3.9984i*10^-3)) 0;
0 0 0 0 1190.25/11.8982i];
B=imag(Y);
del=inv(B)*P;
del1=[del;0];
BB=[-20.1053 20.1053 0 0 0 0;
0 -22.2281 22.2281 0 0 0;
0 0 -19.8032 19.8032 0 0;
0 0 0 250.10004 0 -250.10004;
0 0 0 0 -100.0361 100.0361];
PP=BB*del1;
syms P1;
syms P2;
Ppv=[7;-8;P1-2-0.074*(P1+P2);-25-0.926*(P1+P2);8+P2];
delpv=inv(B)*Ppv;
del1pv=[delpv;0];
PPpv=BB*del1pv;
a=vpa(PPpv,4);
disp(a);

A=[-1.13*10^(-16) 2.647*10^(-17);-1.25*10^(-16) 2.927*10^(-17);0.926 -0.074;0 1;0 1];
b=[7.09-7.0;4.99-1;4.99-3;30-28;10.0-8.0];
f=[-1;-1];
lb=[0;0];
[x,fval,exitflag]=linprog(f,A,b,[],[],lb);
if exitflag==1
   disp(x);
end

A2.4. Line Outage Contingency between Flagstaff & Blythe
P=[7;-8;-2;-25;8];
Y=[1190.25/59.2008i -1190.25/59.2008i 0 0 0;
-1190.25/59.2008i (1190.25/3.968i)+(1190.25/59.2008i) 0 0 0;



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0 0 (1190.25/60.104i) -1190.25/60.104i 0;
0 0 -1190.25/60.104i (1190.25/60.104i)+(1/(3.9984i*10^-3)) 0;
0 0 0 0 1190.25/11.8982i];
B=imag(Y);
del=inv(B)*P;
del1=[del;0];
BB=[-20.1053 20.1053 0 0 0 0;
0 299.9622 0 0 0 -299.9622;
0 0 -19.8032 19.8032 0 0;
0 0 0 250.10004 0 -250.10004;
0 0 0 0 -100.0361 100.0361];
PP=BB*del1;
syms P1;
syms P2;
Ppv=[7;-8;P1-2-0.074*(P1+P2);-25-0.926*(P1+P2);8+P2];
delpv=inv(B)*Ppv;
del1pv=[delpv;0];
PPpv=BB*del1pv;
a=vpa(PPpv,4);
disp(a);

A=[0.926 -0.074;0 1];
b=[2.99;2];
f=[-1;-1];
lb=[0;0];
[x,fval,exitflag]=linprog(f,A,b,[],[],lb);
if exitflag==1
   disp(x);
end

A2.5. Line Outage Contingency between Blythe & Imperial Valley
P=[7;-8;-2;-25;8];
Y=[1190.25/59.2008i -1190.25/59.2008i 0 0 0;
-1190.25/59.2008i (1190.25/3.968i)+(1190.25/59.2008i)+(1190.25/53.5472i) -1190.25/53.5472i 0 0;
0 -1190.25/53.5472i (1190.25/53.5472i) 0 0;
0 0 0 (1/(3.9984i*10^-3)) 0;
0 0 0 0 1190.25/11.8982i];
B=imag(Y);
del=inv(B)*P;
del1=[del;0];
BB=[-20.1053 20.1053 0 0 0 0;
0 299.9622 0 0 0 -299.9622;
0 -22.2281 22.2281 0 0 0;
0 0 0 250.10004 0 -250.10004;
0 0 0 0 -100.0361 100.0361];
PP=BB*del1;
syms P1;
syms P2;
Ppv=[7;-8;P1-2-0.074*(P1+P2);-25-0.926*(P1+P2);8+P2];
delpv=inv(B)*Ppv;
del1pv=[delpv;0];
PPpv=BB*del1pv;
a=vpa(PPpv,4);
disp(a);

A=[ -0.926 0.074;
  -0.926 0.074;
  0.926 0.926;



Arizona State University                                                                          iv
EEE577: Term Project


   0 1];
b=[14.8-3;4.99-2;30-25;10.0-8.0];
f=[-1;-1];
lb=[0;0];
[x,fval,exitflag]=linprog(f,A,b,[],[],lb);
if exitflag==1
   disp(x);
end

A2.6. Line Outage Contingency at One of the Lines between Imperial Valley and
Palo Verde
P=[7;-8;-2;-25;8];
Y=[1190.25/59.2008i -1190.25/59.2008i 0 0 0;
-1190.25/59.2008i (1190.25/3.968i)+(1190.25/59.2008i)+(1190.25/53.5472i) -1190.25/53.5472i 0 0;
0 -1190.25/53.5472i (1190.25/53.5472i)+(1190.25/60.104i) -1190.25/60.104i 0;
0 0 -1190.25/60.104i (1190.25/60.104i)+(2500/19.992i) 0;
0 0 0 0 1190.25/11.8982i];
B=imag(Y);
del=inv(B)*P;
del1=[del;0];
BB=[-20.1053 20.1053 0 0 0 0;
0 299.9622 0 0 0 -299.9622;
0 -22.2281 22.2281 0 0 0;
0 0 -19.8032 19.8032 0 0;
0 0 0 125.05002 0 -125.05002;
0 0 0 0 -100.0361 100.0361];
PP=BB*del1;
syms P1;
syms P2;
Ppv=[7;-8;P1-2-0.074*(P1+P2);-25-0.926*(P1+P2);8+P2];
delpv=inv(B)*Ppv;
del1pv=[delpv;0];
PPpv=BB*del1pv;
a=vpa(PPpv,4);
disp(a);

A2.7. Line Outage Contingency between Palo Verde & Bicknell
P=[7;-8;-2;-25];
Y=[1190.25/59.2008i -1190.25/59.2008i 0 0;
-1190.25/59.2008i (1190.25/3.968i)+(1190.25/59.2008i)+(1190.25/53.5472i) -1190.25/53.5472i 0;
0 -1190.25/53.5472i (1190.25/53.5472i)+(1190.25/60.104i) -1190.25/60.104i;
0 0 -1190.25/60.104i (1190.25/60.104i)+(1/(3.9984i*10^-3))];
B=imag(Y);
del=inv(B)*P;
del1=[del;0];
BB=[-20.1053 20.1053 0 0 0;
0 299.9622 0 0 -299.9622;
0 -22.2281 22.2281 0 0;
0 0 -19.8032 19.8032 0;
0 0 0 250.10004 -250.10004];
PP=BB*del1;
syms P1;
syms P2;
Ppv=[7;-8;P1-2-0.074*P1;-25-0.926*P1];
delpv=inv(B)*Ppv;
del1pv=[delpv;0];
PPpv=BB*del1pv;



Arizona State University                                                                          v
EEE577: Term Project


a=vpa(PPpv,4);
disp(a);

A=[-3.532*10^(-18);
   -0.4548;
   -0.4548;
   0.4712;
   0.4548];
b=[7.09-7.0;14.8-3;4.99-2;4.99-0.0001717;30.0-25];
f=[-1];
lb=[0];
[x,fval,exitflag]=linprog(f,A,b,[],[],lb);
if exitflag==1
   disp(x);
end




Arizona State University                             vi

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Eee577

  • 1. EEE577: Term Project 11/10/2011 EEE577: Term Project STUDY OF TRANSMISSION ADEQUACY BY ARIZONA TRANSMISSION EXPANSION CO. FOR ADDING PV RESOURCES A PROJECT REPORT Submitted by Supriya Chathadi In partial fulfillment for completion of the course EEE577: Power Engineering Operations/Planning at Arizona State University, Tempe [Type text] Page 1
  • 2. EEE577: Term Project Table of Contents 1. Introduction ......................................................................................................................................... 3 2. The Per Unit System ........................................................................................................................... 3 2.1. Advantages................................................................................................................................... 3 3. DC Power Flow................................................................................................................................... 4 3.1. Assumptions................................................................................................................................. 4 3.2. Formulation .................................................................................................................................. 4 4. Actual Power Flows in the System ..................................................................................................... 5 4.1. Bus Terminology ......................................................................................................................... 5 4.2. Initial Calculations ....................................................................................................................... 5 4.3. Power Flow Calculations ............................................................................................................. 5 5. PV Injection ........................................................................................................................................ 6 5.1. Maximization using linprog ......................................................................................................... 6 6. Line Outage Contingencies ................................................................................................................. 6 7. Results ................................................................................................................................................. 7 8. Additional Concerns ........................................................................................................................... 8 9. Conclusion .......................................................................................................................................... 9 10. References ......................................................................................................................................... 9 Appendix 1: System Representation ........................................................................................................ i Appendix 2: MATLAB Codes ................................................................................................................ ii A2.1. Base Case: All Lines under Operation ...................................................................................... ii A2.2. Line Outage Contingency between Flagstaff & Four Corners .................................................. ii A2.3. Line Outage Contingency between Flagstaff & Palo Verde .................................................... iii A2.4. Line Outage Contingency between Flagstaff & Blythe ........................................................... iii A2.5. Line Outage Contingency between Blythe & Imperial Valley ................................................ iv A2.6. Line Outage Contingency at One of the Lines between Imperial Valley and Palo Verde ........ v A2.7. Line Outage Contingency between Palo Verde & Bicknell ...................................................... v Arizona State University 2
  • 3. EEE577: Term Project 1. Introduction A study is performed by Arizona Transmission Expansion Co. (AZTEx) to obtain the transmission adequacies at certain parts of Arizona on adding high level solar PV resources at suggested sites.  This report is based on the study where PV resources are added at Bicknell and Blythe.  The excess generation due to PV injection is dissipated at Imperial Valley and Blythe in proportion to their present load levels. An approximate representation of the system base loads and generation, suggested PV injections and the compensating loads are shown in Appendix 1. 2. The Per Unit System It is a common practice in power system studies to represent all system parameters as a ratio of a defined base quantity in the same units, called the per unit representation. Quantity (Actual units) Per Unit Quantity = Base Quantity (Actual units) Generally, the bases for any two of the system parameters is defined (SB and VB, SB and IB, etc.) are defined from which all other bases are calculated. For example, when SB and VB are given, the following expressions can give other base quantities. SB 3 SB IB = = VB 3 VB 3 (VB/ 3 ) 2 VB 2 ZB = = SB 3 SB 1 YB = ZB 2.1. Advantages  Per unit quantities for similar components (generators, transformers, lines) will lie within a narrow range, regardless of their ratings and sizes.  They are the same on either side of a transformer, independent of voltage level.  The relative values of circuit quantities are clearly identified as unnecessary scaling factors are eliminated.  Use of the constant is reduced in three-phase calculations.  Much simpler for calculations and ideal for computer simulations as well.  It rules out the problem of using different units in different parts of the world by introducing a universal standard. Arizona State University 3
  • 4. EEE577: Term Project 3. DC Power Flow There are a number of ways to perform power flow studies in a system. The simplest formulation is called „DC Power Flow‟. The name is illusive because there is nothing to do with DC in it. Some important observations are made from actual load flow studies and few assumptions are made in order to simplify the calculations and still not vary the results in a large scale. 3.1. Assumptions  The transmission lines are assumed to be purely inductive as the resistances are much smaller than the reactances.  As all machines operate in synchronism, the differences in angles between their voltage phasors are typically very small (less than 30◦). Thus it is assumed that sin δ ≈ δ.  It is seen that the per unit voltages operate close enough to 1p.u. This comes up with an assumption that the voltage magnitudes can be set to 1p.u. at all buses.  As reactive power flow between two buses is dependent on the difference in their voltage magnitudes, an assumption can be made that there is no reactive power flow in the system.  The real power supplied by a bus is much greater than the reactive power supplied and hence reactive power injection is neglected. 3.2. Formulation The actual real power flow is given by the equation: Vi Vj sin ij Pij  xij Based on the assumptions, the power flow equation can be written as: ij i  j Pij   xij xij The power flow matrix for a system can be written from the above expression as follows: Pbus  Bbusδ bus where, Bbus is called the susceptance matrix, given by the imaginary part of the admittance matrix (Ybus)  Y 11 Y 12 ... Y1n   Y 21 Y 22 ... Y 2 n Bbus  imag(Y bus)  imag    ... ... ... ...     Yn 1 Yn 2 ... Ynn  Yii = yi0+yi1+yi2+…+yin Yij = Yji = -yij Arizona State University 4
  • 5. EEE577: Term Project where, yij is the primitive admittance between buses i and j, given by 1 xij 4. Actual Power Flows in the System 4.1. Bus Terminology For ease of calculation, the buses are numbered from 0 to 5, where 0 indicates the reference bus. The following conventions are used in the following sections: Palo Verde (P) – 0 (ref) Four Corners (FC) – 1 Flagstaff (F) – 2 Blythe (BL) – 3 Imperial Valley (I) – 4 Bicknell (BI) – 5 4.2. Initial Calculations The reactance of each line can be calculated as the product of reactance per km of the conductor used and the length of the line. The double line is considered as reactances in parallel. The base and per unit values for all the line are also calculated and tabulated as follows: Table 1: Impedance Calculations SB = 100 MVA = 100MW (no reactive power flows) Reactance (ohms) Base Reactance (ohms) Per Unit Reactance (p.u) x12 204 x 0.2908j = 59.2008j 3452/100 = 1190.25 59.2008j/1190.25 x20 80 x 0.0496j = 3.968j 3452/100 = 1190.25 3.968j/1190.25 2 x23 98 x 0.5464j = 53.5472j 345 /100 = 1190.25 53.5472j /1190.25 x34 110 x 0.5464j = 60.104j 3452/100 = 1190.25 60.104j /1190.25 x40 (357 x 0.056j)/2 = 9.996j 5002/100 = 2500 9.996j /2500 2 x50 41 x 0.2903j = 11.8982j 345 /100 = 1190.25 11.8982j /1190.25 4.3. Power Flow Calculations The values of δ for all buses are found from the expression, δ bus  Bbus Pbus where, Pbus is a 1 matrix showing power injection at various buses. They are given with reference to Palo Verde as shown below: δP 0.0000 δFC -0.3382 δF 0.0100 δBL 0.1000 δI 0.1000 δBI -0.0800 Power flows in the lines are found out by increasing the dimension of δbus by adding a zero for the reference bus, and using the same formula. But, this time the rows of Bbus have entries only at two sites between which the power flow is calculated. Arizona State University 5
  • 6. EEE577: Term Project Consolidated results are shown in section 7. 5. PV Injection It is desired to inject maximum PV resources at Blythe and Bicknell without overloading any of the lines (considering the long term rating). The power injection is compensated at Imperial Valley and Blythe in proportion to their present loads. Thus, their participation factors are calculated as: 25 PFI =  0.926 25  2 2 PFBL =  0.074 25  2 If the power injected at Blythe P1 and that at Bicknell is P2, they are compensated as 0.926(P1+P2) at Imperial Valley and 0.074(P1+P2) at Blythe. Same calculations as done in section 4 are done to obtain power flows in terms of P1 and P2. Optimal values for P1 and P2 are found using linear programming (linprog) in MATLAB. The codes are shown in Appendix 2. 5.1. Maximization using linprog Linear programming is defined as: Min f(x), subject to Ax ≤ b; Aeqx = beq lb ≤ x ≤ ub where, f is called the objective function, x is a vector consisting of decision variables, Ax ≤ b are the inequality constraints, Aeqx = beq are the equality constraints, lb and ub are the limits for the decision variables. The objective in this case is to maximize P1 and P2, with the line flows not exceeding their limits. The problem can be formulated as given below: Max (P1+P2) = -Min (-P1-P2) line flows ≤ line ratings 0 ≤ P1, P2 ≤ ∞ In the constraints, the line flows can be in either direction, thus they might change signs in some cases. As the direction of line flows cannot be predicted sometimes, it might be necessary to manually change the signs for the line flows in order to maximize the PV injection. The resulting values of P1 and P2 are the maximum amounts of power which can be injected in terms of PV resources at Blythe and Bicknell. Results are tabulated in section 7. 6. Line Outage Contingencies This section deals with the study of (N-1) line outage contingencies. The procedure is basically the same as illustrated with all lines under operation, except that the results are going to slightly different because of the difference in Ybus. Arizona State University 6
  • 7. EEE577: Term Project On removing the lines one after another, it is seen that the power generations may not suffice the loads in some cases such as a line outage between Four Corners and Flagstaff or between Palo Verde and Bicknell, as the generation in Four Corners or Bicknell would be lost. In such cases, it is assumed that Palo Verde supplies the power loss due to line outage, for the power flows to converge. This is based on the given suggestion that equivalent generation could be added to another existing generation site. The power flow and maximum PV injection results are tabulated in Section 7. It is seen that a contingency in one of the lines or both between Palo Verde and Imperial Valley is not allowed as the lines overload even for the base case generation and loads. Thus the study of PV injection cannot be done for this case. 7. Results Table 2 gives the line flows in all the lines for including and not including PV injection. For the case on injecting PV resources, the highlighted values indicate the line which might start overloading if little more PV resources are added to the system. It is seen that for a line outage between Palo Verde and Imperial Valley, line overloading occurs even without injecting PV resources. Table 2: Per Unit Power Flows in All Lines for with/without PV Injection Per Unit Power PFC-F PP-F PF-BL PI-BL PP-I PBI-P Flows (SB = 100MVA) Condition No With No PV With No PV With No PV With No With PV No With PV PV PV PV PV PV PV PV Line ratings 15+15 7.09 7.09 14.8 14.8 4.99 4.99 4.99 4.99 =30 30 10 10 With all lines 7 7 3 1.8010 2 2.8010 0.0002 4.9897 25 29.9998 8 8.1988 under operation With line outage - - 9.773 5.1902 1.773 2.8098 0.2271 4.5358 25.23 30 8 8.1872 between Flagstaff & Four Corners With line outage 7 7 - - 1 1 3 1.0100 28 30 8 10 between Flagstaff & Palo Verde With line outage 7 7 1 1 - - 2 0.9900 27 29 8 10 between Flagstaff & Blythe With line outage 7 7 3 1.3551 2 2.3551 - - 25 30 8 8.6449 between Blythe & Imperial Valley With line outage at 24.064 one of the lines 7 - 3.9357 - 2.9357 - 0.9357 - (rating - 8 - between Imperial in this Valley and Palo case is 15) Verde With line outage 7 7 3 1.8162 2 2.8162 0.0002 4.9897 25 29.8162 - - between Palo Verde & Bicknell Table 3 summarizes the maximum amount of PV resources which can be injected at Bicknell and Blythe for different cases. The study of injecting PV into the system is not possible when a line outage occurs between Imperial Valley and Palo Verde because of overloading, as shown in Table 2. Arizona State University 7
  • 8. EEE577: Term Project Maximum PV can be injected in the system when all lines are under operation, which is about 1078.79 MW. Table 3: Consolidated Results for Maximum PV Injection at Blythe and Bicknell Maximum PV Maximum PV Total PV Injection Injection at Blythe Injection at Bicknell (MW) (MW) (MW) With all lines under operation 1058.91 19.88 1078.79 With line outage between 1010.75 18.72 1029.47 Flagstaff & Four Corners With line outage between 230.89 200.00 430.89 Flagstaff & Palo Verde With line outage between 338.88 200.00 538.88 Flagstaff & Blythe With line outage between 475.46 64.49 539.96 Blythe & Imperial Valley With line outage at one of the lines between Imperial Valley - - - and Palo Verde With line outage between 1058.96 - 1058.96 Palo Verde & Bicknell 8. Additional Concerns  One of the assumptions of DC load flow studies is to consider that the voltage magnitudes at all buses are 1 p.u. This comes up with a conclusion that there will be no reactive power flows between any two buses, as difference in voltage magnitudes between them is zero. Thus inclusion of reactive power flows, voltage magnitudes, their limits and constraints are all inter-related. Including reactive power flows or voltage magnitudes automatically gives rise to the other. The study will become more complex and detailed on doing it. The power flow equations in this case would be the following: Vi Vj ij Pij  xij  Vi ( Vi  Vj ) Qij  xij The above equations still assume the following:  The transmission lines are purely inductive.  δ is very small and hence, sin δ ≈ δ.  There is no reactive power injection at any bus.  The active power flow „west of river‟ for the base case is almost negligible. It is 0.0001717 p.u., from Imperial Valley to Blythe. But with PV injection, it is nearly the rating of the line (4.9897 p.u.). The „worst‟ single line outage is the outage of a line between Imperial Valley and Palo Verde as one of the lines start overloading for the base case itself. The maximum active power flow in the line is 0.9357 p.u. Arizona State University 8
  • 9. EEE577: Term Project  If it is possible to add another transmission line, it is logical to add a line between Flagstaff and Imperial Valley. A large amount of power produced by Palo Verde and Bicknell could not be transmitted efficiently because of the relatively lower ratings on the lines between Flagstaff and Blythe, Blythe and Imperial Valley. A major share of the system load occurs at Imperial Valley, thus the transmission lines connecting to it must have compatible ratings. If a transmission line made of type (3) conductor is added between Flagstaff and Imperial Valley, a transmission path of Palo Verde to Flagstaff to Imperial Valley would be chosen for effective transmission of the generated power. Yet another option is to add one more line between Imperial Valley and Palo Verde, if it is not required to supply more loads anywhere else. 9. Conclusion  It is seen that the maximum PV injection is possible when all lines are in service, and it can be further improved by adding more transmission lines.  It is seen that the system is not properly designed for an N-1 line outage contingency, and thus has to be improved 10. References [1] John J. Grainger, William D. Stevenson, “Power System Analysis”, Tata McGraw-Hill Publications, January 1994. [2] Anomynous, “The Power Flow Equations”, available at: class.ece.iastate.edu/ee458/PowerFlowEquations.doc [3] Wikipedia, notes appearing on the subject of per-unit systems, available at: en.wikipedia.org/wiki/Per-unit_system Arizona State University 9
  • 10. EEE577: Term Project Appendix 1: System Representation 7 p.u. Four Corners (2) 8 p.u. Flagstaff (1) 0.074(P1+P2) p.u. 2 p.u. Blythe (3) P1 p.u. 0.926(P1+P2) p.u. 20 p.u. Imperial Valley (4) Palo Verde (0) 8 p.u. 25 p.u. Bicknell (5) P2 p.u. Legend Generation/Load Site Transmission Line Base Case Generation/Load PV Injection/Load Compensation Arizona State University i
  • 11. EEE577: Term Project Appendix 2: MATLAB Codes A2.1. Base Case: All Lines under Operation P=[7;-8;-2;-25;8]; Y=[1190.25/59.2008i -1190.25/59.2008i 0 0 0; -1190.25/59.2008i (1190.25/3.968i)+(1190.25/59.2008i)+(1190.25/53.5472i) -1190.25/53.5472i 0 0; 0 -1190.25/53.5472i (1190.25/53.5472i)+(1190.25/60.104i) -1190.25/60.104i 0; 0 0 -1190.25/60.104i (1190.25/60.104i)+(1/(3.9984i*10^-3)) 0; 0 0 0 0 1190.25/11.8982i]; B=imag(Y); del=inv(B)*P; del1=[del;0]; BB=[-20.1053 20.1053 0 0 0 0; 0 299.9622 0 0 0 -299.9622; 0 -22.2281 22.2281 0 0 0; 0 0 -19.8032 19.8032 0 0; 0 0 0 250.10004 0 -250.10004; 0 0 0 0 -100.0361 100.0361]; PP=BB*del1; syms P1; syms P2; Ppv=[7;-8;P1-2-0.074*(P1+P2);-25-0.926*(P1+P2);8+P2]; delpv=inv(B)*Ppv; del1pv=[delpv;0]; PPpv=BB*del1pv; a=vpa(PPpv,4); disp(a); A=[-3.532*10^(-18) 8.272*10^(-19); -0.4548 0.07523; -0.4548 0.07523; 0.4712 0.001232; 0.4548 0.9248; 0 1]; b=[7.09-7.0;14.8-2.9998;4.99-1.9998;4.99-0.0001717;30-25.0002;10-8]; f=[-1;-1]; lb=[0;0]; [x,fval,exitflag]=linprog(f,A,b,[],[],lb); if exitflag==1 disp(x); end A2.2. Line Outage Contingency between Flagstaff & Four Corners P=[-8;-2;-25;8]; Y=[(1190.25/3.968i)+(1190.25/53.5472i) -1190.25/53.5472i 0 0; -1190.25/53.5472i (1190.25/53.5472i)+(1190.25/60.104i) -1190.25/60.104i 0; 0 -1190.25/60.104i (1190.25/60.104i)+(1/(3.9984i*10^-3)) 0; 0 0 0 1190.25/11.8982i]; B=imag(Y); del=inv(B)*P; del1=[del;0]; BB=[299.9622 0 0 0 -299.9622; -22.2281 22.2281 0 0 0; 0 -19.8032 19.8032 0 0; 0 0 250.10004 0 -250.10004; 0 0 0 -100.0361 100.0361]; Arizona State University ii
  • 12. EEE577: Term Project PP=BB*del1; syms P1; syms P2; Ppv=[-8;P1-2-0.074*(P1+P2);-25-0.926*(P1+P2);8+P2]; delpv=inv(B)*Ppv; del1pv=[delpv;0]; PPpv=BB*del1pv; a=vpa(PPpv,4); disp(a); A=[-0.4548 0.07523;-0.4548 0.07523;0.4712 0.001232;0.4548 0.9248;0 1]; b=[14.8-9.773;4.99-1.773;4.99-0.2271;30-25.23;10-8]; f=[-1;-1]; lb=[0;0]; [x,fval,exitflag]=linprog(f,A,b,[],[],lb); if exitflag==1 disp(x); end A2.3. Line Outage Contingency between Flagstaff & Palo Verde P=[7;-8;-2;-25;8]; Y=[1190.25/59.2008i -1190.25/59.2008i 0 0 0; -1190.25/59.2008i (1190.25/59.2008i)+(1190.25/53.5472i) -1190.25/53.5472i 0 0; 0 -1190.25/53.5472i (1190.25/53.5472i)+(1190.25/60.104i) -1190.25/60.104i 0; 0 0 -1190.25/60.104i (1190.25/60.104i)+(1/(3.9984i*10^-3)) 0; 0 0 0 0 1190.25/11.8982i]; B=imag(Y); del=inv(B)*P; del1=[del;0]; BB=[-20.1053 20.1053 0 0 0 0; 0 -22.2281 22.2281 0 0 0; 0 0 -19.8032 19.8032 0 0; 0 0 0 250.10004 0 -250.10004; 0 0 0 0 -100.0361 100.0361]; PP=BB*del1; syms P1; syms P2; Ppv=[7;-8;P1-2-0.074*(P1+P2);-25-0.926*(P1+P2);8+P2]; delpv=inv(B)*Ppv; del1pv=[delpv;0]; PPpv=BB*del1pv; a=vpa(PPpv,4); disp(a); A=[-1.13*10^(-16) 2.647*10^(-17);-1.25*10^(-16) 2.927*10^(-17);0.926 -0.074;0 1;0 1]; b=[7.09-7.0;4.99-1;4.99-3;30-28;10.0-8.0]; f=[-1;-1]; lb=[0;0]; [x,fval,exitflag]=linprog(f,A,b,[],[],lb); if exitflag==1 disp(x); end A2.4. Line Outage Contingency between Flagstaff & Blythe P=[7;-8;-2;-25;8]; Y=[1190.25/59.2008i -1190.25/59.2008i 0 0 0; -1190.25/59.2008i (1190.25/3.968i)+(1190.25/59.2008i) 0 0 0; Arizona State University iii
  • 13. EEE577: Term Project 0 0 (1190.25/60.104i) -1190.25/60.104i 0; 0 0 -1190.25/60.104i (1190.25/60.104i)+(1/(3.9984i*10^-3)) 0; 0 0 0 0 1190.25/11.8982i]; B=imag(Y); del=inv(B)*P; del1=[del;0]; BB=[-20.1053 20.1053 0 0 0 0; 0 299.9622 0 0 0 -299.9622; 0 0 -19.8032 19.8032 0 0; 0 0 0 250.10004 0 -250.10004; 0 0 0 0 -100.0361 100.0361]; PP=BB*del1; syms P1; syms P2; Ppv=[7;-8;P1-2-0.074*(P1+P2);-25-0.926*(P1+P2);8+P2]; delpv=inv(B)*Ppv; del1pv=[delpv;0]; PPpv=BB*del1pv; a=vpa(PPpv,4); disp(a); A=[0.926 -0.074;0 1]; b=[2.99;2]; f=[-1;-1]; lb=[0;0]; [x,fval,exitflag]=linprog(f,A,b,[],[],lb); if exitflag==1 disp(x); end A2.5. Line Outage Contingency between Blythe & Imperial Valley P=[7;-8;-2;-25;8]; Y=[1190.25/59.2008i -1190.25/59.2008i 0 0 0; -1190.25/59.2008i (1190.25/3.968i)+(1190.25/59.2008i)+(1190.25/53.5472i) -1190.25/53.5472i 0 0; 0 -1190.25/53.5472i (1190.25/53.5472i) 0 0; 0 0 0 (1/(3.9984i*10^-3)) 0; 0 0 0 0 1190.25/11.8982i]; B=imag(Y); del=inv(B)*P; del1=[del;0]; BB=[-20.1053 20.1053 0 0 0 0; 0 299.9622 0 0 0 -299.9622; 0 -22.2281 22.2281 0 0 0; 0 0 0 250.10004 0 -250.10004; 0 0 0 0 -100.0361 100.0361]; PP=BB*del1; syms P1; syms P2; Ppv=[7;-8;P1-2-0.074*(P1+P2);-25-0.926*(P1+P2);8+P2]; delpv=inv(B)*Ppv; del1pv=[delpv;0]; PPpv=BB*del1pv; a=vpa(PPpv,4); disp(a); A=[ -0.926 0.074; -0.926 0.074; 0.926 0.926; Arizona State University iv
  • 14. EEE577: Term Project 0 1]; b=[14.8-3;4.99-2;30-25;10.0-8.0]; f=[-1;-1]; lb=[0;0]; [x,fval,exitflag]=linprog(f,A,b,[],[],lb); if exitflag==1 disp(x); end A2.6. Line Outage Contingency at One of the Lines between Imperial Valley and Palo Verde P=[7;-8;-2;-25;8]; Y=[1190.25/59.2008i -1190.25/59.2008i 0 0 0; -1190.25/59.2008i (1190.25/3.968i)+(1190.25/59.2008i)+(1190.25/53.5472i) -1190.25/53.5472i 0 0; 0 -1190.25/53.5472i (1190.25/53.5472i)+(1190.25/60.104i) -1190.25/60.104i 0; 0 0 -1190.25/60.104i (1190.25/60.104i)+(2500/19.992i) 0; 0 0 0 0 1190.25/11.8982i]; B=imag(Y); del=inv(B)*P; del1=[del;0]; BB=[-20.1053 20.1053 0 0 0 0; 0 299.9622 0 0 0 -299.9622; 0 -22.2281 22.2281 0 0 0; 0 0 -19.8032 19.8032 0 0; 0 0 0 125.05002 0 -125.05002; 0 0 0 0 -100.0361 100.0361]; PP=BB*del1; syms P1; syms P2; Ppv=[7;-8;P1-2-0.074*(P1+P2);-25-0.926*(P1+P2);8+P2]; delpv=inv(B)*Ppv; del1pv=[delpv;0]; PPpv=BB*del1pv; a=vpa(PPpv,4); disp(a); A2.7. Line Outage Contingency between Palo Verde & Bicknell P=[7;-8;-2;-25]; Y=[1190.25/59.2008i -1190.25/59.2008i 0 0; -1190.25/59.2008i (1190.25/3.968i)+(1190.25/59.2008i)+(1190.25/53.5472i) -1190.25/53.5472i 0; 0 -1190.25/53.5472i (1190.25/53.5472i)+(1190.25/60.104i) -1190.25/60.104i; 0 0 -1190.25/60.104i (1190.25/60.104i)+(1/(3.9984i*10^-3))]; B=imag(Y); del=inv(B)*P; del1=[del;0]; BB=[-20.1053 20.1053 0 0 0; 0 299.9622 0 0 -299.9622; 0 -22.2281 22.2281 0 0; 0 0 -19.8032 19.8032 0; 0 0 0 250.10004 -250.10004]; PP=BB*del1; syms P1; syms P2; Ppv=[7;-8;P1-2-0.074*P1;-25-0.926*P1]; delpv=inv(B)*Ppv; del1pv=[delpv;0]; PPpv=BB*del1pv; Arizona State University v
  • 15. EEE577: Term Project a=vpa(PPpv,4); disp(a); A=[-3.532*10^(-18); -0.4548; -0.4548; 0.4712; 0.4548]; b=[7.09-7.0;14.8-3;4.99-2;4.99-0.0001717;30.0-25]; f=[-1]; lb=[0]; [x,fval,exitflag]=linprog(f,A,b,[],[],lb); if exitflag==1 disp(x); end Arizona State University vi