Ingenieur Vol. 75 ingenieur July 2018-FA | Page 20

INGENIEUR
have high fault currents breaching the safety factor
of 90% of the VCBs and in some instances, even
breaching the 20 kA rating of the VCBs.
However, when the Main Substation reaches
firm loading, i.e. the load is more than 50% of the
transformer capacity, the utility opens the bus
section between the transformers, effectively
reducing the fault current to almost half its value.
However, the practice is not to open the bus section
unless the Main Substation has reached firm
loading due to reliability concerns. Another option
is to replace the 11 kV VCBs with higher ratings, say
25 kA. This will entail a substantial cost on the part
of the utility, which will eventually be passed on to
the consumers through tariff adjustments.
GUIDELINES ON NEM AND SELF-
CONSUMPTION BY EC
The EC has come up with various guidelines on
LSS, NEM, self-consumption, etc., especially
on requirements for utility approval. There have
been some accusations by the RE Industry that
some of these guidelines appear one-sided. This
is especially so since no engagement with the
Industry or other stakeholders was held before the
release of these guidelines.
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VOL 75
55 JULY-SEPTEMBER
JUNE 2013 2018
THE WAY FORWARD
Many countries in the region, including Singapore,
have allowed for competition at the retail level.
Many utilities now only own and operate the
Transmission and Distribution (T & D) systems
while generation and retail are open to bidding.
To put Distributed Generation on a firm footing,
the country will need to decide whether we still
need a monopolistic, vertically integrated utility in
the 21 st century. Many of the obstacles to further
increase the contribution of RE generators can
be overcome by opening Distribution and Retail to
open competition. All new developments can be
allowed to choose their electricity provider, who
will buy from the utility at a higher voltage and
distribute in their development at a lower voltage.
Of course, these arrangements must make
financial sense, so that the small distributor can
make a reasonable margin to stay in business.
These developments will certainly try to maximize
the generation of electricity onsite, especially
using RE sources, and only purchase the balance
from the utility. There should be no subsidy
schemes for RE in the long run, and the utility
should be allowed to make a reasonable profit, not
too excessive, so it can efficiently maintain its T &
D network.