S. THONGSUK, A. NGAOPITAKKUL 1041
Table 6. The comparison of electrical line losses and per-
centage change between base case (no DG) and 2 DG that 8
MVA DG is installed at bus 4.
2 MVA 4 MVA 6 MVA 8 MVA
Loss % Loss Loss % LossLoss % Loss Loss%Loss
Bus (MW) (MW) (MW) (MW)
1 0.451 25.63 0.483 34.540.531 47.91 0.59465.46
2 0.437 21.73 0.525 46.240.648 80.50 0.807124.79
3 0.454 26.46 0.504 40.390.581 61.84 0.68791.36
4 0.806 124.51 1.503 318.662.277 534.26 3.283814.48
5 0.804 123.96 1.451 304.182.218 517.83 3.141774.93
6 0.84 133.98 1.528 325.632.567 615.04 3.652917.27
7 0.815 127.02 1.51 320.612.269 532.03 3.257807.24
8 0.451 25.63 0.483 34.540.531 47.91 0.59465.46
On the other hand, when the capacity of DG at bus 4 is
varied and th e capacity of other DG does not change, it is
noticed that the electrical line losses at each bus are
slightly increased more than the base case (no DG). This
also indicates the slight mismatch between DG capacity
and size of load.
Considering the load at bus 7 and bus 8 that is less
than 1 MW and load is installed at the end of the distri-
bution system, it can be seen that the electrical line losses
tend to increase, when the capacity of DG is increased.
However, if the DG capacity is not too large (less than 4
MVA), the electrical line losses also decrease. This also
indicates the slight mismatch between DG capacity and
size of load. From the Figure 5(d) and Table 6, it is
clearly seen that as the DG capacity increases, the elec-
trical line losses also increases.
5. Conclusions
This paper presented the impact of electrical line losses
when multi-distributed generation is connected to distri-
bution system. In order to evaluate the impact of multi-
DG for electrical line losses, the line losses of the case of
no DG and with DG are compared. The results show that
when DG is installed close to the substation, the electri-
cal line losses are reduced. However, if DG capacity be-
comes larger and the distance between DG and load is
longer, the electrical line losses tend to increase. The
results indicate that the capacity of DG, location of DG,
location of load and size of load play an important role
for electrical line losses as shown in Figures 4 and 5.
6. Acknowledgements
The authors wish to gratefully acknowledge financial
support for this research from the King Mongkut’s Insti-
tute of Technology Ladkrabang Research fund. And en-
ergy policy and planning office (EPPO), Ministry of En-
ergy, Thailand. They would like also to thank for the
DIgSILENT presented in this paper which is supported
by Provincial Electricity Authority (PEA).
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