traditional
MVAC systems, single circuit consists three
conductors (or three conductors and neutral line)
for three-phase transmission.
In contrast, MVDC lines use converters, which
allow for flexible and precise power flow control. Therefore, is
common practice MVAC systems implement
a radial configuration with tie switches normally
open; and, the event fault, isolate the
faulted section and close the tie switch restore
power adjacent sections.6. shown Figure 4-6,
MVDC systems can adopt variety network
configurations, each which affects the stability,
flexibility, and scalability the power system. Voltage choice can
significantly impact the size, cost and
complexity the converters and switchgear
used MVDC system, and the converter
topology, protection strategy and system
voltage need chosen together.40
MVDC technologies and operational considerations
§ Conversion efficiency. Even
if fault occurs, power can still supplied
through alternative routes, greatly enhancing
power supply reliability.2 Network configuration and
reliability
Network configuration critical factor in
determining the reliability and operational efficiency
of power system.
4. repurpose existing
AC infrastructure for MVDC distribution
networks, crucial select appropriate
DC voltage.
. For example,
when replacing existing two-circuit overhead
MVAC network with MVDC system, the upper
conductor can assigned the positive (+) and
the lower conductor the negative (–). However, this might cause power flow
to concentrate certain lines.3 Line configuration
MVDC systems have several unique characteristics
that oblige line configuration approached
differently from system. MVDC systems
the line configuration usually consists two
conductors and two conductors and a
neutral line. Significant energy loss
can occur during voltage conversion, and if
the input output voltage level difference is
substantial, losses typically increase.4 times the voltage
as DC, but the ageing and service life of
AC equipment with must also taken
into account, described the following
subsections.
Depending the required level reliability of
the MVDC network, possible operate
with fully meshed interconnections adopt a
radial configuration when economic issues take
precedence:
§ Radial configuration offers ease management
and clear transmission path; the event a
fault, though, the entire power supply along the
affected route might interrupted.
§ Hybrid configuration: some cases, a
combination radial and mesh configurations
may used. theory, possible apply
up approximately 1.
Once the line configuration decided, and when
multiple circuits are used, the placement of
conductors must thought about.
§ Mesh configuration (including ring structure)
provides higher reliability, allows power
to supplied through multiple paths.
As shown Figure 4-7, the line configuration of
an MVDC line can categorized into asymmetric
monopole, symmetric monopole, and bipole types,
based converter topology, grounding scheme,
the number conductors, and other key factors.6. general, operating with
multiple distribution feeders interconnected under
normal conditions improves both reliability and
efficiency.
As result, multiple feeders can interconnected
and operated continuously.
§ Economic feasibility.
4. While this involves higher cost,
it offers large advantages scalability and
stability.
§ infrastructure reuse
