The output of capacitor and DGs corresponding

to 24 hrs load variation are shown in

Fig. 2, Fig. 5 and Fig.8. Comparing figures 5 and 8, it is observed that with capacitors, the

size of DGs obtained are lower. This is due to the fact of reactive support

from the capacitors. The total

power loss for summer time varying load with capacitor, DG, and capacitor and

DG together are obtained and are shown in Fig. 3, Fig. 6 and Fig. 9. It

is found that total loss is minimal at bus 30 and bus 6 with capacitor

and DG respectively. So candidate buses for capacitor and DG are 30 and 6 buses

respectively. The voltage

profiles obtained with and without installation of capacitor and DG are shown

in Fig. 1, Fig. 4, Fig. 7, and Fig. 10. The voltage profile obtained with both

capacitor and DG is better compared to the case with individual presence of

capacitor and DGs. The Capacitor and DG sizes are obtained corresponding to the

minimum loss at the buses 30 and bus 6 respectively. The voltage stability

index before and after device installation are shown in Figs. 11-12. As

observed from the figures with optimal allocation of DG and capacitors voltage

stability index is improved considerably at each node. Also VSI of node 18 (The

node with minimum VSI) has improved from 0.83002 p.u to 0.83954 p.u, 0.90365

p.u, and 0.90717 p.u with installation of capacitor, DG and capacitor and DG

together respectively at 7th hour. VSI of node 18 (The node with

minimum VSI) is improved from 0.66739 p.u to 0.69716 p.u, 0.9527 p.u, and

0.95366 p.u with installation of capacitor, DG and capacitor and DG together

respectively at 18th hour. Improvement in minimum voltage, VSI and

reduction in total real power loss are shown in Fig. 13- Fig. 15. There is

considerable improvement with DGs and capacitor and DGs together in voltage

profile, VSI, and reduction in real power losses. TPL is minimum at 7th

hour and maximum at 18th hour since the load is low at 7th

hour and is high at 18th hour. TPL is reduced from 56.329 kW to

47.031 kW, 21.24 kW and 16.904 kW at 7th hour with installation of

capacitor, DG and capacitor and DG together respectively. TPL is reduced from 254.91

kW to 210.3 kW, 170.59 kW and 161.88 kW at 18th hour with

installation of capacitor, DG and capacitor and DG together respectively. It is observed that TPL, cost of energy loss

is varies with the load pattern variation. Minimum voltage and minimum VSI are

varies inversely proportional with the load pattern variation

Optimal

capacitor and DG sizes obtained are given in Table 1. As observed from the

table, the sizes of DGs reduce with support of reactive power from capacitors. The

cost of energy loss with and without installation of these devices is given in

Table 2. Cost of reactive power obtained from capacitor and cost of real and

reactive powers obtained from DG are given in Table 3. Cost of savings is given

in Table 4. It is observed that the total real and

reactive power losses are observed lower with capacitor and DG compared to

single capacitor or single DG placement. The real and reactive power

requirements from the substation reduces with capacitor and DGs and are observed

lower with capacitor and DG together compared to single capacitor or single DG

placement.

Finally,

it is observed that cost of energy savings per annum at 7th hour is

lower and at 22nd hour is higher. This is based on the load pattern

at the corresponding hours. The cost of energy savings at 7th hour

is 2753.36 $ and at 22nd hour is 27821 $ respectively. There is huge

cost savings obtained with capacitors and DGs in the system.