5.46
Barriers the uptake MVDC grids
insulation between dissimilar metals, and use
of sacrificial anodes.
§ Control environmental conditions through
physical design reduce water pooling and
by methods that limit water salt ingress.3 Current and voltage sensing
Current and voltage sensors are critical
components the converter control and fault
detection functions MVDC power systems.
§ Installation devices that limit short-circuit
current.
§ Careful design insulation and grounding to
prevent electrically induced corrosion. Possible alternative current sensing
. Double
insulation can also useful enhance
insulation systems and reduce the risk arc
propagation.
§ Use protective coatings such paint, epoxy
or galvanization. Electrical equipment
such circuit breakers, switches, couplers can
generate arcs when electrical contacts separate
under conductive conditions during regular use.
MVDC arcs can occur during normal operating
conditions (when interrupting load fault currents)
and from equipment failure (due poor contact
between conductors, wire insulation damage).1.
Series arcs, caused poor contact between
conductors, can occur normal load levels,
making them very difficult detect, and so
particularly dangerous. However, MVDC power systems
where continuous load current flows fault
situation, sustained arc discharges can easily
transition into sustained plasma, significantly
increasing the risk fire equipment failure.
5.
In power systems, the current zero-crossing
limits the duration arc when current is
interrupted.1). Ideal
current sensors should able measure and
track fault currents quickly and accurately With
MVDC, they are likely based different
techniques from AC.
§ Arc analysis: calculate the expected arc
incidence energy specific points the power
system and prepare appropriate protective
equipment and procedures.
§ Maintenance and repair procedures reduce
likelihood arc formation: This includes
regular inspections, use appropriate tools,
and correct disconnection methods.
§ Use impressed cathodic protection to
supply external current the system to
inhibit corrosion.
In conventional MVAC power systems, current
transformers (CTs) are primarily used for current
measurement under normal and transient
conditions. Current sensing technical
challenge, and MVDC systems fault currents can
be much larger, and rise much faster, than their AC
counterparts. CTs are unlikely suitable for
current sensing MVDC applications given CTs’
limited bandwidth and saturation during high fault
currents.
Measures reduce the risk arcing MVDC
systems include:
§ Use appropriate design minimize the risk
of arc formation: This includes defining arc
hazard levels and safe operating ranges based
on supply voltage and load power.2 Arcing
An arc form high temperature, high pressure
plasma temperatures around 000-7 000 °C,
leading hazardous situations such personal
injuries electrical fires.
§ Implementation detection technologies and
standards: identify arc accidents early in
MVDC systems and prevent their escalation.1.
§ Careful choice and design circuit breakers
and switchgear (in light the unique
characteristics MVDC operation, outlined
in Section 4
