EE 3033 FUZZY LOGIC SYSTEMS

OPTIMAL VOLTAGE REGULATOR PLACEMENT IN A RADIAL DISTRIBUTION SYSTEM USING FUZZY LOGIC

Submitted by :-

1. Roushan Kumar – B110135EE2. Raghuveer Verma – B110638EE3. Prashankar – B110820EE4. Rishabh Nischal- B110842EE

1.ACTUAL SYSTEM BLOCK DIAGRAM

2.Fuzzy controller

4.FUZZIFICATION AND DEFUZZIFCATION MEMBERSHIP

The inputs to the rules are the voltages and power loss indices and the output consequent is the suitability of voltage regulator placement. The rules are summarized in the fuzzy decision matrix in table given above. Fuzzy variables of PLI (power loss index) are low, low-medium, medium, high-medium, high.

Fuzzy variables for Voltage regulator suitability index are low, low-medium ,medium, high-medium, high.

Defuzzification techniques:

Once the suitability membership function of a node is calculated, It must

be defuzzified in order to determine the buses suitability ranking. The centroid

method of defuzzification is used, this finds the center of area of the

membership function. Thus, the voltage regulator suitability index is

determined by:

Centroid method

S = ∫μs(z).zdz/(∫μs(z)dz)

5. Rule Base

6.Testing and Validation

EXAMPLE: 15 BUS RADIAL DISTRIBUTION SYSTEM

Line Data & Load Data of 15 Practical RDS:

Fig -bus Radial Distribution System

Input data of a 15 bus practical RDS.

Line Parameters

R= 0.6108Ω/km

X= 0.3521Ω/km

Diversity factor=1.5

Branch No.

From bus

To bus

P (kW)

Length (km) Bus No. Q(kVAr)

1 1 2 0 4.57 1 0

2 2 3 0 0.58 2 0

3 2 4 50.4 1.84 3 37.8

4 4 5 80 0.73 4 60

5 5 6 50.4 0.73 5 37.8

6 4 7 50.4 0.34 6 37.8

7 7 8 80 0.69 7 60

8 7 9 80 0.75 8 60

9 9 10 0 0.28 9 0

10 10 11 80 0.95 10 60

11 9 12 80 0.87 11 60

12 12 13 80 2.65 12 60

13 13 14 0 0.93 13 0

14 13 15 40 0.67 14 30

15 15 16 80 0.92 15 60

16 15 17 80 0.95 16 60

Table - line and load data for 15 bus

Algorithm for optimum voltage regulator placement in RDS using FES:

Step 1. Read line and load data.

Step 2. Run load flows for the system and compute the voltages at each bus, real and

reactive power losses of the system.

Step 3. Install the voltage regulator at every bus and compute the total real power loss of

the system at each case and convert into normalized values.

Step4. Obtain optimal number of VRs and location of VRs by giving voltages nd power

loss indices as inputs to FES.

Step 5. Obtain the optimal tap position of VR using Eqn. (3), so that the voltage is within

the specified limits.

Step 6. Again run the load flows with VR, then compute voltages at all buses, real

and reactive power losses. If voltages are not within the limits, go to step 3.

Step 7. Determine the reduction in power loss and net saving by using objective function

(Eqn (2)).

Step 8. Print results.

Step 9. Stop.

Matlab Program Of 15 Bus

Clear;

clc;

pf=1;

linedata=load('datafl.dat');

powerdata=load('datafp.dat');

nline=length(linedata(:,1));

nbus=length(powerdata(:,1));

disp('1.CONSTANT POWER');

disp('2.CONSTANT CURRENT');

disp('3.CONSTANT IMPEDANCE');

disp('4.EXPONENTIAL LOAD');

disp('5.COMPOSITE LOAD');

ch=input('Enter type of load');

%RUNNING LOAD FLOW BEFORE VOLTAGE REGULATORS PLACEMENT

disp(' LOAD FLOW REULTS BEFORE VOLTAGE REGULATOR');

loadbefvr();

%loadwithorig();

lop=1;

for i=1:nbus

vrp(i)=0;

vrpfin(i)=0;

vrpbuk(i)=0;

vrpbst(i)=0;

vrfin(i)=0;

vr(i)=0;

vold(i)=1;

vbef(i)=v(i);

vs(i)=v(i);

end

%PUSH BACK ALGORITHM

while(lop)

l=0;

for i=1:nbus

if (vs(i)<=0.95)

l=l+1;

vp(l)=i;

vrpbst(i)=1;

end

end

if(l~=0)

pushbst();

vfinbst

end

l=0;

for i=1:nbus

if(vs(i)>1.05)

l=l+1;

vp(l)=i;

vrpbuk(i)=1;

end

end

if(l~=0)

pushbuk();

vfinbuk

end

f=0;

disp(' places where voltage regulators are placed after algorithm');

for i=1:nbus

if(vrpbst(i)==1|vrpbuk(i)==1)

vrp(i)=1;

i

end

end

for i=1:nbus

if(vrp(i)==1)

vrpfin(i)=1;

end

end

loadwithvr47bstbk();

vr

vrp

lop=0;

for i=1:nbus

if(vrpfin(i)==1)

vold(i)=v1(i);

else

vold(i)=1;

end

vs(i)=v1(i);

vrfin(i)=vrfin(i)+vr(i);

vr(i)=0;

vrp(i)=0;

vrpbuk(i)=0;

vrpbst(i)=0;

vaft(i)=v1(i);

end

for i=1:nbus

if(v1(i)<=0.95|v1(i)>1.05)

lop=1;

break;

else

lop=0;

end

end

end

nvr=0;

for i=1:nbus

if(vrpfin(i)==1)

nvr=nvr+1;

end

end

regbvr

regavr

totenlbvr

totenlavr

energysaved=(totenlbvr-totenlavr)

disp(' LOSS REDUCED IN "KW"');

lossred=(tpl-tpl1)*1000*basemva;

cstofavb=1.65*10^5;

llf=(0.8*lf*lf+0.2*lf);

benefit=lossred*8760*2.93*llf-(cstofavb*(0.1+0.1)*nvr)

Output

At load=5

regbvr =6.8000

regavr =1.6826

totenlbvr = 3.5602e+006

totenlavr = 2.9608e+005

energysaved =3.2641e+006

LOSS REDUCED IN "KW" benefit = 9.2339e+005

Line Data & Load Data of 15 Practical RDS

Input data of a 47 bus practical RDS.

Line Parameters

R= 0.6108Ω/km

X= 0.3521Ω/km

Diversity factor=1.5

Results of back tracking algorithm:

The proposed method is illustrated with two radial distribution systems of 15 buses

and 47 buses.

Example 1

Consider 15 bus Radial Distribution System. The Line and Load data is given in

Appendix and the single line diagram is shown in Fig. For the positioning of voltage

regulators, the upper and lower bounds of voltage are taken as ±5% of base value. The

voltage regulators are of 11kV, 200MVA with 32 steps of 0.00625 p.u. each.

Fig. - Single line diagram of 15 bus RDS

Load flow solution for 15 bus practical RDS without and with voltage regulators is given in Table.

Observing the voltage levels in first column of Table, Ideally, voltage regulators are to be installed at

all buses except at bus 1. However, in practice, it is not economical to have more number of voltage

regulators at all buses to get the voltages within specified limits and hence by applying proposed

back tracking algorithm the required optimal number of voltage regulators that will maintain the

voltage profile within above limits is determined. By applying the above algorithm for the above

systems it is found that voltage regulators at bus 4 are sufficient to maintain the voltage profile at all

buses.

Table- Load Flow Results pbus and qbus Voltage Regulators

Bus No.

pbus qbus

1 0 0

2 0 0

3 0.3360 0.2520

4 0.5333 .4000

5 0.3360 0.2520

6 0.3360 0.2520

7 0.5333 0.4000

8 0.5333 0.4000

9 0 0

10 0.5333 0.4000

11 0.5333 0.4000

12 0.5333 0.4000

13 0 0

14 0.2667 0.2000

15 0.5333 0.4000

The reduction in real power loss, net saving and %voltage regulation for the system is shown

in Table below.

Table Summary of Results of 15 bus RDS

Before After(VR at bus 4)

Ploss (%) 3.5602e+006 2.9608e+005

Net saving (in Rs.) ----- 3.2641e+006

Voltage regulation (%) 6.8000 1.6826

It is observed that from Table above, without voltage regulators in the system the

percentage power loss is 3.5602e+006 and percentage voltage regulation is 6.8000. With voltage

regulators at all bus 4 the percentage power loss is reduced to 2.9608e+005and percentage voltage

regulation is reduced to 1.6826. The optimal net saving is increased to Rs. 3.2641e+006.

7. CONCLUSION

In radial distribution systems it is necessary to maintain voltage levels

at various buses by using capacitors or conductor grading or placing VR at

suitable locations. The proposed Back tracking algorithm determines the

optimal number, location and tap positions of voltage regulators to maintain

voltage profile with in the desired limits and reduces the losses in the system

which in turn maximizes the net savings in the operation of the system. In

addition to the back tracking algorithm a method using Fuzzy is also proposed

and the results of FES are compared with the results of back tracking

algorithm. It is concluded that the FES also gives the optimal location and

number along with the tap setting of the voltage regulators. The proposed FES

provides good voltage regulation, and reduces the power loss which in turn

increases the net savings when compared to the back tracking algorithm. The

algorithms are tested with two Radial distribution systems consisting of 15

buses and the results are provided.