initial commit / add all books

18 files changed, 654 insertions, 0 deletions

diff --git a/14/CH7/EX7.1/example_7_1.sce b/14/CH7/EX7.1/example_7_1.sce
new file mode 100755
index 000000000..9657f3cd5
--- /dev/null
+++ b/14/CH7/EX7.1/example_7_1.sce
@@ -0,0 +1,59 @@
+//chapter 7
+//Example 7.1
+//Page 170
+//busadmittancematrix
+clear;clc;
+//Given
+//Voltage Sources
+Ea = 1.5;
+Eb = 1.5*(cos(-36.87 * %pi / 180) + %i * sin(-36.87 * %pi / 180))
+Ec = 1.5;
+//admittances
+Ya = -%i*0.8;
+Yb = Ya;
+Yc= Ya;
+Yd = -%i*5;
+Ye = -%i*8;
+Yf = -%i*4;
+Yg = -%i*2.5;
+Yh = Yd;
+//current sourcs
+I1 = Ea * Ya;
+I2 = Eb * Yb;
+I3 = I1;
+I4 = 0;
+disp('Current Sources are')
+printf("\n I1 = - j%.2f per unit",-imag(I1))
+printf("\n I2 = %.2f - j%.2f per unit",real(I2),-imag(I2))
+printf("\n I3 = - j%.2f per unit \n\n",-imag(I3))
+//Self-admittances
+Y11 = Yd + Yf + Ya;
+Y22 = Yh + Yg + Yb;
+Y33 = Ye + Yc + Yg + Yf;
+Y44 = Yd + Ye + Yh;
+disp('Self-admittances are')
+printf("\n Y11 = - j%.2f per unit",-imag(Y11))
+printf("\n Y22 = - j%.2f per unit",-imag(Y22))
+printf("\n Y33 = - j%.2f per unit",-imag(Y33))
+printf("\n Y44 = - j%.2f per unit\n\n",-imag(Y44))
+//Mutual-admittances
+Y12 = 0;Y21 = Y12;
+Y13 = -Yf;Y31 = Y13;
+Y14 = -Yd;Y41 = Y14;
+Y23 = -Yg;Y32 = Y23;
+Y24 = -Yh;Y42 = Y24;
+Y34 = -Ye;Y43 = Y34;
+disp('Mutual admittances are')
+printf("\n Y12 = Y21 = %.2f per unit",imag(Y12))
+printf("\n Y13 = Y31 = j%.2f per unit",imag(Y13))
+printf("\n Y14 = Y41 = j%.2f per unit",imag(Y14))
+printf("\n Y23 = Y32 = j%.2f per unit",imag(Y23))
+printf("\n Y24 = Y42 = j%.2f per unit",imag(Y24))
+printf("\n Y34 = Y43 = j%.2f per unit \n\n",imag(Y34))
+//Matrix Form
+I = [I1 ; I2 ; I3 ; I4];
+Y = [Y11 Y12 Y13 Y14;Y21 Y22 Y23 Y24;Y31 Y32 Y33 Y34;Y41 Y42 Y43 Y44];
+disp('Current Vector =')
+disp(I)
+disp('Bus admittance matrix =')
+disp(Y)
\ No newline at end of file
diff --git a/14/CH7/EX7.1/result_ex_7_1.txt b/14/CH7/EX7.1/result_ex_7_1.txt
new file mode 100755
index 000000000..b34d7b100
--- /dev/null
+++ b/14/CH7/EX7.1/result_ex_7_1.txt
@@ -0,0 +1,38 @@
+ Current Sources are   
+
+ I1 = - j1.20 per unit
+ I2 = -0.72 - j0.96 per unit
+ I3 = - j1.20 per unit 
+
+ 
+ Self-admittances are   
+
+ Y11 = - j9.80 per unit
+ Y22 = - j8.30 per unit
+ Y33 = - j15.30 per unit
+ Y44 = - j18.00 per unit
+
+ 
+ Mutual admittances are   
+
+ Y12 = Y21 = 0.00 per unit
+ Y13 = Y31 = j4.00 per unit
+ Y14 = Y41 = j5.00 per unit
+ Y23 = Y32 = j2.50 per unit
+ Y24 = Y42 = j5.00 per unit
+ Y34 = Y43 = j8.00 per unit 
+
+ 
+ Current Vector =   
+ 
+  - 1.2i                    
+  - 0.7200017 - 0.9599987i  
+  - 1.2i                    
+    0                       
+ 
+ Bus admittance matrix =   
+ 
+  - 9.8i    0       4.i      5.i   
+    0     - 8.3i    2.5i     5.i   
+    4.i     2.5i  - 15.3i    8.i   
+    5.i     5.i     8.i    - 18.i  
diff --git a/14/CH7/EX7.2/example_7_2.sce b/14/CH7/EX7.2/example_7_2.sce
new file mode 100755
index 000000000..6e0025ab1
--- /dev/null
+++ b/14/CH7/EX7.2/example_7_2.sce
@@ -0,0 +1,46 @@
+//chapter 7
+//Example 7.2
+//Page 171
+//solvingBAM
+clear;clc;
+//Voltage Sources
+Ea = 1.5;
+Eb = 1.5*(cos(-36.87 * %pi / 180) + %i * sin(-36.87 * %pi / 180))
+Ec = 1.5;
+//admittances
+Ya = -%i*0.8;
+Yb = Ya;
+Yc= Ya;
+Yd = -%i*5;
+Ye = -%i*8;
+Yf = -%i*4;
+Yg = -%i*2.5;
+Yh = Yd;
+//current sourcs
+I1 = Ea * Ya;
+I2 = Eb * Yb;
+I3 = I1;
+I4 = 0;
+//Self-admittances
+Y11 = Yd + Yf + Ya;
+Y22 = Yh + Yg + Yb;
+Y33 = Ye + Yc + Yg + Yf;
+Y44 = Yd + Ye + Yh;
+//Mutual-admittances
+Y12 = 0;Y21 = Y12;
+Y13 = -Yf;Y31 = Y13;
+Y14 = -Yd;Y41 = Y14;
+Y23 = -Yg;Y32 = Y23;
+Y24 = -Yh;Y42 = Y24;
+Y34 = -Ye;Y43 = Y34;
+//Matrix Form
+I = [I1 ; I2 ; I3 ; I4];
+Y = [Y11 Y12 Y13 Y14;Y21 Y22 Y23 Y24;Y31 Y32 Y33 Y34;Y41 Y42 Y43 Y44];
+V = Y\I;
+disp('Node Voltages V1,V2,V3 and V4 in per unit is')
+disp(V)
+disp('In polar form')
+printf("\n V1 = %.2f /_%.2f per unit",abs(V(1,1)),atan(imag(V(1,1)),real(V(1,1))) * 180 / %pi)
+printf("\n V2 = %.2f /_%.2f per unit",abs(V(2,1)),atan(imag(V(2,1)),real(V(2,1))) * 180 / %pi)
+printf("\n V3 = %.2f /_%.2f per unit ",abs(V(3,1)),atan(imag(V(3,1)),real(V(3,1))) * 180 / %pi)
+printf("\n V4 = %.2f /_%.2f per unit \n\n",abs(V(4,1)),atan(imag(V(4,1)),real(V(4,1))) * 180 / %pi)
\ No newline at end of file
diff --git a/14/CH7/EX7.2/result_ex_7_2.txt b/14/CH7/EX7.2/result_ex_7_2.txt
new file mode 100755
index 000000000..7f71a5c14
--- /dev/null
+++ b/14/CH7/EX7.2/result_ex_7_2.txt
@@ -0,0 +1,14 @@
+
+ Node Voltages V1,V2,V3 and V4 in per unit is   
+ 
+    1.4110556 - 0.2668324i  
+    1.3830779 - 0.3507654i  
+    1.4058649 - 0.2824044i  
+    1.400977 - 0.2970680i   
+ 
+ In polar form   
+
+ V1 = 1.44 /_-10.71 per unit
+ V2 = 1.43 /_-14.23 per unit
+ V3 = 1.43 /_-11.36 per unit 
+ V4 = 1.43 /_-11.97 per unit 
diff --git a/14/CH7/EX7.3/example_7_3.sce b/14/CH7/EX7.3/example_7_3.sce
new file mode 100755
index 000000000..cd0f9631c
--- /dev/null
+++ b/14/CH7/EX7.3/example_7_3.sce
@@ -0,0 +1,57 @@
+//chapter 7
+//Example 7.3
+//Page 177
+//matrixpartition
+clear;clc;
+//Given
+//Voltage Sources
+Ea = 1.5;
+Eb = 1.5*(cos(-36.87 * %pi / 180) + %i * sin(-36.87 * %pi / 180))
+Ec = 1.5;
+//admittances
+Ya = -%i*0.8;
+Yb = Ya;
+Yc= Ya;
+Yd = -%i*5;
+Ye = -%i*8;
+Yf = -%i*4;
+Yg = -%i*2.5;
+Yh = Yd;
+//Self-admittances
+Y11 = Yd + Yf + Ya;
+Y22 = Yh + Yg + Yb;
+Y33 = Ye + Yg + Yf;
+Y44 = Yd + Ye + Yh;
+//Mutual-admittances
+Y12 = 0;Y21 = Y12;
+Y13 = -Yf;Y31 = Y13;
+Y14 = -Yd;Y41 = Y14;
+Y23 = -Yg;Y32 = Y23;
+Y24 = -Yh;Y42 = Y24;
+Y34 = -Ye;Y43 = Y34;
+//Bus Impedance Matrix
+Y = [Y11 Y12 Y13 Y14;Y21 Y22 Y23 Y24;Y31 Y32 Y33 Y34;Y41 Y42 Y43 Y44];
+K = Y(1:2,1:2);
+L = Y(1:2,3:4);
+L_T = Y(3:4,1:2);
+M = Y(3:4,3:4);
+M_1 = inv(M);
+LMT = L * M_1 *  L_T;
+Ybus = K - LMT;
+Y_12 = - Ybus(1,2);
+Y_10 = Ybus(1,1) - Y_12;
+Y_20 = Y_10;
+printf("\n Admittance between buses 1 and 2 = - j%.4f per unit\n",-imag(Y_12))
+printf("\n Admittance between buse 1 and reference bus = - j%.4f per unit\n",-imag(Y_10))
+printf("\n Admittance between buse 2 and reference bus = - j%.4f per unit\n",-imag(Y_20))
+Z = 1/Y_12 + 1/Y_10 + 1/Y_20;
+I = (Ea-Eb) / Z;
+printf("\n I = %.2f /_%.2f per unit \n",abs(I),atan(imag(I),real(I)) * 180 / %pi)
+Pa = Ea * I';
+printf("\n Power out of source ''a'' = %.3f + j%.3f per unit \n",real(Pa),imag(Pa))
+Pb = Eb * I';
+printf("\n Power out of source ''b'' = %.3f - j%.3f per unit \n",real(Pb),-imag(Pb))
+Var = (abs(I))^2 * imag(Z);
+printf("\n Reactie voltamperes in circuit equivalent = %.3f per unit \n",Var)
+V_1 = Ea - I/Y_10;
+printf("\n Voltage at node 1 = %.3f - j%.3f per unit \n",real(V_1),-imag(V_1))
\ No newline at end of file
diff --git a/14/CH7/EX7.3/result_ex_7_3.txt b/14/CH7/EX7.3/result_ex_7_3.txt
new file mode 100755
index 000000000..59d606f59
--- /dev/null
+++ b/14/CH7/EX7.3/result_ex_7_3.txt
@@ -0,0 +1,15 @@
+ Admittance between buses 1 and 2 = - j4.0736 per unit
+
+ Admittance between buse 1 and reference bus = - j0.8000 per unit
+
+ Admittance between buse 2 and reference bus = - j0.8000 per unit
+
+ I = 0.35 /_-18.43 per unit 
+
+ Power out of source 'a' = 0.492 + j0.164 per unit 
+
+ Power out of source 'b' = 0.492 - j0.164 per unit 
+
+ Reactie voltamperes in circuit equivalent = 0.328 per unit 
+
+ Voltage at node 1 = 1.363 - j0.410 per unit 
diff --git a/14/CH7/EX7.4/example_7_4.sce b/14/CH7/EX7.4/example_7_4.sce
new file mode 100755
index 000000000..cd2d95325
--- /dev/null
+++ b/14/CH7/EX7.4/example_7_4.sce
@@ -0,0 +1,48 @@
+//chapter 7
+//Example 7.4
+//Page 177
+//matrixmanipulation
+clear;clc;
+//admittances
+Ya = -%i*0.8;
+Yb = Ya;
+Yc= Ya;
+Yd = -%i*5;
+Ye = -%i*8;
+Yf = -%i*4;
+Yg = -%i*2.5;
+Yh = Yd;
+//Self-admittances
+Y11 = Yd + Yf + Ya;
+Y22 = Yh + Yg + Yb;
+Y33 = Ye + Yg + Yf;
+Y44 = Yd + Ye + Yh;
+//Mutual-admittances
+Y12 = 0;Y21 = Y12;
+Y13 = -Yf;Y31 = Y13;
+Y14 = -Yd;Y41 = Y14;
+Y23 = -Yg;Y32 = Y23;
+Y24 = -Yh;Y42 = Y24;
+Y34 = -Ye;Y43 = Y34;
+//Bus Impedance Matrix
+Y = [Y11 Y12 Y13 Y14;Y21 Y22 Y23 Y24;Y31 Y32 Y33 Y34;Y41 Y42 Y43 Y44];
+//Removing node 4
+[row_4,column_4] = size(Y)
+Y_bus_4 = zeros(row_4-1,column_4-1);
+for a = 1:row_4-1
+    for b = 1:column_4-1
+    Y_bus_4(a,b) = Y(a,b) - (Y(a,column_4) * Y(row_4,b) / Y(row_4,column_4))
+    end
+end
+disp('Y bus matrix after removing node four')
+disp(Y_bus_4)
+//Removing node 3
+[row_3,column_3] = size(Y_bus_4)
+Y_bus_3 = zeros(row_3-1,column_3-1);
+for c = 1:row_3-1
+    for d = 1:column_3-1
+    Y_bus_3(c,d) = Y_bus_4(c,d) - (Y_bus_4(c,column_3) * Y_bus_4(row_3,d) / Y_bus_4(row_3,column_3))
+    end
+end
+disp('Y bus matrix after removing node three')
+disp(Y_bus_3)
diff --git a/14/CH7/EX7.4/result_ex_7_4.txt b/14/CH7/EX7.4/result_ex_7_4.txt
new file mode 100755
index 000000000..c4041c593
--- /dev/null
+++ b/14/CH7/EX7.4/result_ex_7_4.txt
@@ -0,0 +1,10 @@
+ Y bus matrix after removing node four   
+ 
+  - 8.4111111i    1.3888889i    6.2222222i  
+    1.3888889i  - 6.9111111i    4.7222222i  
+    6.2222222i    4.7222222i  - 10.944444i  
+ 
+ Y bus matrix after removing node three   
+ 
+  - 4.8736041i    4.0736041i  
+    4.0736041i  - 4.8736041i  
diff --git a/14/CH7/EX7.5/example_7_5.sce b/14/CH7/EX7.5/example_7_5.sce
new file mode 100755
index 000000000..fca56d5d3
--- /dev/null
+++ b/14/CH7/EX7.5/example_7_5.sce
@@ -0,0 +1,52 @@
+//chapter 7
+//Example 7.5
+//Page 181
+//introcapacitor
+clear;clc;
+//Voltage Sources
+Ea = 1.5;
+Eb = 1.5*(cos(-36.87 * %pi / 180) + %i * sin(-36.87 * %pi / 180))
+Ec = 1.5;
+//admittances
+Ya = -%i*0.8;
+Yb = Ya;
+Yc= Ya;
+Yd = -%i*5;
+Ye = -%i*8;
+Yf = -%i*4;
+Yg = -%i*2.5;
+Yh = Yd;
+//Value of capacitor introduced in node 4
+C = 5.0 ;//in per unit
+Xc = %i*C;
+//current sourcs
+I1 = Ea * Ya;
+I2 = Eb * Yb;
+I3 = I1;
+I4 = 0;
+//Self-admittances
+Y11 = Yd + Yf + Ya;
+Y22 = Yh + Yg + Yb;
+Y33 = Ye + Yc + Yg + Yf;
+Y44 = Yd + Ye + Yh;
+//Mutual-admittances
+Y12 = 0;Y21 = Y12;
+Y13 = -Yf;Y31 = Y13;
+Y14 = -Yd;Y41 = Y14;
+Y23 = -Yg;Y32 = Y23;
+Y24 = -Yh;Y42 = Y24;
+Y34 = -Ye;Y43 = Y34;
+//Matrix Form
+I = [I1 ; I2 ; I3 ; I4];
+Y = [Y11 Y12 Y13 Y14;Y21 Y22 Y23 Y24;Y31 Y32 Y33 Y34;Y41 Y42 Y43 Y44];
+V = Y\I;
+E_th = V(4,1);
+Z = inv(Y);
+Z_th = Z(4,4);
+I_c = E_th / (Z_th - Xc);
+disp('Thevenin equivalent of the circuit behind node four')
+printf("\n Eth = %.2f /_%.2f per unit \n\n",abs(E_th),atan(imag(E_th),real(E_th)) * 180 / %pi)
+disp('Thevenin equivalent impedance')
+printf("\n Z_th = j%.2f per unit \n\n",imag(Z_th))
+disp('Current drawn by the capacitor')
+printf("\n Ic = %.2f /_%.2f per unit \n\n",abs(I_c),atan(imag(I_c),real(I_c)) * 180 / %pi)
\ No newline at end of file
diff --git a/14/CH7/EX7.5/result_ex_7_5.txt b/14/CH7/EX7.5/result_ex_7_5.txt
new file mode 100755
index 000000000..5737ed596
--- /dev/null
+++ b/14/CH7/EX7.5/result_ex_7_5.txt
@@ -0,0 +1,13 @@
+ Thevenin equivalent of the circuit behind node four   
+
+ Eth = 1.43 /_-11.97 per unit 
+
+ 
+ Thevenin equivalent impedance   
+
+ Z_th = j0.47 per unit 
+
+ 
+ Current drawn by the capacitor   
+
+ Ic = 0.32 /_78.03 per unit 
diff --git a/14/CH7/EX7.6/example_7_6.sce b/14/CH7/EX7.6/example_7_6.sce
new file mode 100755
index 000000000..5ca30afd6
--- /dev/null
+++ b/14/CH7/EX7.6/example_7_6.sce
@@ -0,0 +1,60 @@
+//chapter 7
+//Example 7.6
+//Page 181
+//currentinjection
+clear;clc;
+//Voltage Sources
+Ea = 1.5;
+Eb = 1.5*(cos(-36.87 * %pi / 180) + %i * sin(-36.87 * %pi / 180))
+Ec = 1.5;
+//admittances
+Ya = -%i*0.8;
+Yb = Ya;
+Yc= Ya;
+Yd = -%i*5;
+Ye = -%i*8;
+Yf = -%i*4;
+Yg = -%i*2.5;
+Yh = Yd;
+//current sourcs
+I1 = Ea * Ya;
+I2 = Eb * Yb;
+I3 = I1;
+I4 = 0;
+//Current Injected
+I4_1 = -0.316 * (cos(78.03 * %pi / 180) + %i * sin(78.03 * %pi / 180));
+//Self-admittances
+Y11 = Yd + Yf + Ya;
+Y22 = Yh + Yg + Yb;
+Y33 = Ye + Yc + Yg + Yf;
+Y44 = Yd + Ye + Yh;
+//Mutual-admittances
+Y12 = 0;Y21 = Y12;
+Y13 = -Yf;Y31 = Y13;
+Y14 = -Yd;Y41 = Y14;
+Y23 = -Yg;Y32 = Y23;
+Y24 = -Yh;Y42 = Y24;
+Y34 = -Ye;Y43 = Y34;
+//Matrix Form
+I = [I1 ; I2 ; I3 ; I4];
+Y = [Y11 Y12 Y13 Y14;Y21 Y22 Y23 Y24;Y31 Y32 Y33 Y34;Y41 Y42 Y43 Y44];
+V = Y\I;
+Z = inv(Y);
+V_ci_1 = I4_1 * Z(1,4);
+V_ci_2 = I4_1 * Z(2,4);
+V_ci_3 = I4_1 * Z(3,4);
+V_ci_4 = I4_1 * Z(4,4);
+disp('Voltages with all emfs shorted')
+printf("\n V1 = %.2f /_%.2f per unit",abs(V_ci_1),atan(imag(V_ci_1),real(V_ci_1)) * 180 / %pi)
+printf("\n V2 = %.2f /_%.2f per unit",abs(V_ci_2),atan(imag(V_ci_2),real(V_ci_2)) * 180 / %pi)
+printf("\n V3 = %.2f /_%.2f per unit ",abs(V_ci_3),atan(imag(V_ci_3),real(V_ci_3)) * 180 / %pi)
+printf("\n V4 = %.2f /_%.2f per unit \n\n",abs(V_ci_4),atan(imag(V_ci_4),real(V_ci_4)) * 180 / %pi)
+disp('Resulting voltages are determined by superposition of voltages caused by injected current and emfs shorted to the node voltage')
+V_new_1 = V(1,1) + V_ci_1;
+V_new_2 = V(2,1) + V_ci_2;
+V_new_3 = V(3,1) + V_ci_3;
+V_new_4 = V(4,1) + V_ci_4;
+printf("\n V1 = %.2f /_%.2f per unit",abs(V_new_1),atan(imag(V_new_1),real(V_new_1)) * 180 / %pi)
+printf("\n V2 = %.2f /_%.2f per unit",abs(V_new_2),atan(imag(V_new_2),real(V_new_2)) * 180 / %pi)
+printf("\n V3 = %.2f /_%.2f per unit ",abs(V_new_3),atan(imag(V_new_3),real(V_new_3)) * 180 / %pi)
+printf("\n V4 = %.2f /_%.2f per unit \n\n",abs(V_new_4),atan(imag(V_new_4),real(V_new_4)) * 180 / %pi)
\ No newline at end of file
diff --git a/14/CH7/EX7.6/result_ex_7_6.txt b/14/CH7/EX7.6/result_ex_7_6.txt
new file mode 100755
index 000000000..8b2d43b47
--- /dev/null
+++ b/14/CH7/EX7.6/result_ex_7_6.txt
@@ -0,0 +1,15 @@
+ Voltages with all emfs shorted   
+
+ V1 = 0.13 /_-11.97 per unit
+ V2 = 0.13 /_-11.97 per unit
+ V3 = 0.13 /_-11.97 per unit 
+ V4 = 0.15 /_-11.97 per unit 
+
+ 
+ Resulting voltages are determined by superposition of voltages caused by injected current and emfs shorted to the node vo 
+      ltage                                                                                                                
+
+ V1 = 1.57 /_-10.81 per unit
+ V2 = 1.56 /_-14.04 per unit
+ V3 = 1.57 /_-11.41 per unit 
+ V4 = 1.58 /_-11.97 per unit 
diff --git a/14/CH7/EX7.7/example_7_7.sce b/14/CH7/EX7.7/example_7_7.sce
new file mode 100755
index 000000000..ff0beda77
--- /dev/null
+++ b/14/CH7/EX7.7/example_7_7.sce
@@ -0,0 +1,66 @@
+//chapter 7
+//Example 7.7
+//Page 186
+//matrixmodification
+clear;clc;
+//Voltage Sources
+Ea = 1.5;
+Eb = 1.5*(cos(-36.87 * %pi / 180) + %i * sin(-36.87 * %pi / 180))
+Ec = 1.5;
+//admittances
+Ya = -%i*0.8;
+Yb = Ya;
+Yc= Ya;
+Yd = -%i*5;
+Ye = -%i*8;
+Yf = -%i*4;
+Yg = -%i*2.5;
+Yh = Yd;
+//Capacitor
+Zb = -%i * 5
+//current sourcs
+I1 = Ea * Ya;
+I2 = Eb * Yb;
+I3 = I1;
+I4 = 0;
+//Self-admittances
+Y11 = Yd + Yf + Ya;
+Y22 = Yh + Yg + Yb;
+Y33 = Ye + Yc + Yg + Yf;
+Y44 = Yd + Ye + Yh;
+//Mutual-admittances
+Y12 = 0;Y21 = Y12;
+Y13 = -Yf;Y31 = Y13;
+Y14 = -Yd;Y41 = Y14;
+Y23 = -Yg;Y32 = Y23;
+Y24 = -Yh;Y42 = Y24;
+Y34 = -Ye;Y43 = Y34;
+//Matrix Form
+I = [I1 ; I2 ; I3 ; I4];
+Y = [Y11 Y12 Y13 Y14;Y21 Y22 Y23 Y24;Y31 Y32 Y33 Y34;Y41 Y42 Y43 Y44];
+V = Y\I;
+Z = inv(Y);
+disp('Original bus impedance matrix')
+disp(Z)
+[m,n] = size(Z)
+for i = 1:m
+    for j = 1:n
+    Z(5,i) = Z(i,j);
+    Z(i,5) = Z(i,j)
+    end
+end
+Z(5,5) = Z(4,4) + Zb;
+disp('Modified bus impedance matrix')
+disp(Z)
+[m1,n1] = size(Z);
+Z_new = zeros(m1-1,n1-1);
+for c = 1:m1-1
+    for d = 1:n1-1
+    Z_new(c,d) = Z(c,d) - ((Z(c,5)*Z(5,d)) / Z(5,5));
+    end
+end
+disp('Modified bus impedance matrix after eliminating fifth row and column')
+disp(Z_new)
+V_4 = Z_new(4,:) * I;
+printf("\n V4 = %.2f /_%.2f per unit \n\n",abs(V_4),atan(imag(V_4),real(V_4)) * 180 / %pi)
+disp('V4 same as found in Example 7.6')
\ No newline at end of file
diff --git a/14/CH7/EX7.7/result_ex_7_7.txt b/14/CH7/EX7.7/result_ex_7_7.txt
new file mode 100755
index 000000000..96f733069
--- /dev/null
+++ b/14/CH7/EX7.7/result_ex_7_7.txt
@@ -0,0 +1,26 @@
+ Original bus impedance matrix   
+ 
+    0.4774405i    0.3705997i    0.4019598i    0.4142155i  
+    0.3705997i    0.4871730i    0.3922274i    0.4125934i  
+    0.4019598i    0.3922274i    0.4558128i    0.4231910i  
+    0.4142155i    0.4125934i    0.4231910i    0.4733096i  
+ 
+ Modified bus impedance matrix   
+ 
+    0.4774405i    0.3705997i    0.4019598i    0.4142155i    0.4142155i  
+    0.3705997i    0.4871730i    0.3922274i    0.4125934i    0.4125934i  
+    0.4019598i    0.3922274i    0.4558128i    0.4231910i    0.4231910i  
+    0.4142155i    0.4125934i    0.4231910i    0.4733096i    0.4733096i  
+    0.4142155i    0.4125934i    0.4231910i    0.4733096i  - 4.5266904i  
+ 
+ Modified bus impedance matrix after eliminating fifth row and column   
+ 
+    0.5153434i    0.4083541i    0.4406840i    0.4575258i  
+    0.4083541i    0.5247796i    0.4307999i    0.4557341i  
+    0.4406840i    0.4307999i    0.4953761i    0.4674398i  
+    0.4575258i    0.4557341i    0.4674398i    0.5227987i  
+
+ V4 = 1.58 /_-11.97 per unit 
+
+ 
+ V4 same as found in Example 7.6   
diff --git a/14/CH7/EX7.8/example_7_8.sce b/14/CH7/EX7.8/example_7_8.sce
new file mode 100755
index 000000000..6d9de8a4f
--- /dev/null
+++ b/14/CH7/EX7.8/example_7_8.sce
@@ -0,0 +1,76 @@
+//chapter 7
+//Example 7.8
+//Page 187
+//directZbus
+clear;clc;
+//Given Impedances
+Z10 = %i*1.2;
+Z21 = %i*0.2;
+Z23 = %i*0.15;
+Z13 = %i*0.3;
+Z30 = %i*1.5;
+//1*1 bus
+Zbus = Z10;
+disp('1X1 bus impedance matrix with bus 1 and reference bus')
+disp(Zbus)
+//to establish bus 2
+[m,n] = size(Zbus)
+for i = 1:m
+    for j = 1:n
+    Zbus(2,i) = Zbus(i,j);
+    Zbus(i,2) = Zbus(i,j)
+    end
+end
+Zbus(2,2) = Z10 + Z21;
+disp('After establishing bus 2')
+disp(Zbus)
+//to establish bus 3 with impedance connecting it to bus 1
+[m,n] = size(Zbus)
+for i = 1:m
+    for j = 1
+    Zbus(3,i) = Zbus(i,j);
+    Zbus(i,3) = Zbus(i,j);
+    end
+end
+Zbus(3,3) = Z10 + Z13;
+disp('Connecting a impedance between bus 3 and 1')
+disp(Zbus)
+//to add an impedance from bus 3 to reference
+[m,n] = size(Zbus)
+for i = 1:m
+    for j = 1:n
+    Zbus(4,i) = Zbus(i,j);
+    Zbus(i,4) = Zbus(i,j)
+    end
+end
+Zbus(4,4) = Zbus(3,3) + Z30;
+disp('After adding impedance from bus 3 to reference')
+disp(Zbus)
+[m1,n1] = size(Zbus);
+Z_new = zeros(m1-1,n1-1);
+for c = 1:m1-1
+    for d = 1:n1-1
+    Z_new(c,d) = Zbus(c,d) - ((Zbus(c,4)*Zbus(4,d)) / Zbus(4,4));
+    end
+end
+disp('After elemination of 4th row and column')
+disp(Z_new)
+//to add the impedance between buses 2 and 3
+Z_new(1,4) = Z_new(1,2) - Z_new(1,3);
+Z_new(2,4) = Z_new(2,2) - Z_new(2,3);
+Z_new(3,4) = Z_new(3,2) - Z_new(3,3);
+Z_new(4,1) = Z_new(1,4);
+Z_new(4,2) = Z_new(2,4);
+Z_new(4,3) = Z_new(3,4);
+Z_new(4,4) = Z23 + Z_new(2,2) + Z_new(3,3) - 2*Z_new(2,3);
+disp('After adding impedance between buses 2 and 3')
+disp(Z_new)
+[m1,n1] = size(Z_new);
+Zbus_new = zeros(m1-1,n1-1);
+for c = 1:m1-1
+    for d = 1:n1-1
+    Zbus_new(c,d) = Z_new(c,d) - ((Z_new(c,4)*Z_new(4,d)) / Z_new(4,4));
+    end
+end
+disp('The Bus Impedance Matrix is')
+disp(Zbus_new)
\ No newline at end of file
diff --git a/14/CH7/EX7.8/result_ex_7_8.txt b/14/CH7/EX7.8/result_ex_7_8.txt
new file mode 100755
index 000000000..22eff95fd
--- /dev/null
+++ b/14/CH7/EX7.8/result_ex_7_8.txt
@@ -0,0 +1,40 @@
+ 1X1 bus impedance matrix with bus 1 and reference bus   
+ 
+    1.2i  
+ 
+ After establishing bus 2   
+ 
+    1.2i    1.2i  
+    1.2i    1.4i  
+ 
+ Connecting a impedance between bus 3 and 1   
+ 
+    1.2i    1.2i    1.2i  
+    1.2i    1.4i    1.2i  
+    1.2i    1.2i    1.5i  
+ 
+ After adding impedance from bus 3 to reference   
+ 
+    1.2i    1.2i    1.2i    1.2i  
+    1.2i    1.4i    1.2i    1.2i  
+    1.2i    1.2i    1.5i    1.5i  
+    1.2i    1.2i    1.5i    3.i   
+ 
+ After elemination of 4th row and column   
+ 
+    0.72i    0.72i    0.6i   
+    0.72i    0.92i    0.6i   
+    0.6i     0.6i     0.75i  
+ 
+ After adding impedance between buses 2 and 3   
+ 
+    0.72i    0.72i    0.6i     0.12i  
+    0.72i    0.92i    0.6i     0.32i  
+    0.6i     0.6i     0.75i  - 0.15i  
+    0.12i    0.32i  - 0.15i    0.62i  
+ 
+ The Bus Impedance Matrix is   
+ 
+    0.6967742i    0.6580645i    0.6290323i  
+    0.6580645i    0.7548387i    0.6774194i  
+    0.6290323i    0.6774194i    0.7137097i  
diff --git a/14/CH7/EX7.9/example_7_9.sce b/14/CH7/EX7.9/example_7_9.sce
new file mode 100755
index 000000000..b8a2db4b6
--- /dev/null
+++ b/14/CH7/EX7.9/example_7_9.sce
@@ -0,0 +1,16 @@
+//chapter 7
+//Example 7.9
+//Page 190
+//impedacedetermination
+clear;clc;
+//Given Impedances
+Z10 = %i*1.2;
+Z21 = %i*0.2;
+Z23 = %i*0.15;
+Z13 = %i*0.3;
+Z30 = %i*1.5;
+//Solution
+Z_eq = (Z13 * (Z21+Z23) / (Z13+Z21+Z23));
+Z11 = Z10 * (Z30 + Z_eq) / (Z10 + Z30 + Z_eq);
+disp('Z11 is given by')
+disp(Z11)
\ No newline at end of file
diff --git a/14/CH7/EX7.9/result_ex_7_9.txt b/14/CH7/EX7.9/result_ex_7_9.txt
new file mode 100755
index 000000000..80692f125
--- /dev/null
+++ b/14/CH7/EX7.9/result_ex_7_9.txt
@@ -0,0 +1,3 @@
+ Z11 is given by   
+ 
+    0.6967742i