Increasing power of maritime power systems requires up-to-date failure protection
Modern energy systems for maritime and offshore applications are becoming increasingly larger and more powerful. Manufacturers of these systems face several challenges, such as high system powers, interconnection of multiple buses to form closed bus or ring systems and dealing with high-capacity energy storage systems. Ultra-fast solid-state breakers are the key to up-to-date fault protection.
The traditional way to increase the power of a system is to increase the system voltage (690 V, 3.3 kV, 6.6 kV, 11 kV,…). This solves the capacity limitations of the bus, cabling and breakers. The current trend is to connect more power capacities by adding power sources, including by running systems in parallel while maintaining a lower system voltage. This is to some extent preferable to other options due to availability of power electronics drives and energy storage systems (ESSs) of required capacity.
In recent years, power systems that do not use transformers have become popular in marine applications, due to their compact size and reduced weight. Technical space on ships is expensive because it is at the expense of cargo or passenger space. An important challenge with these systems is the high 'prospective short current', the maximum current that will flow in the event of a short circuit. The availability of traditional, mechanical DC breakers with a capacity of 800-1,000 V in the range of 30-50 kA (or higher at lower voltages) is very limited, while potential system fault levels are usually higher than 100 kA. Without fuses or solid-state breakers, it is almost impossible to achieve the required protection against short circuits.
Closed bus or ring systems
Using multibus interconnection to form closed bus or ring systems provides greater energy efficiency in the system. After all, the number of combustion generators in use can be minimized at any time, while maintaining system integrity and protection against errors. Closed-bus systems must enable fast fault isolation and rapid system recovery to achieve a fault-tolerant system.
An important feature of an interconnected closed bus system, with good shielding against faults and faults, is full or partial selectivity so that the system coordinates the protection devices. These protection methods are relatively easy to achieve with AC systems. A wide range of types and brands of protection relays are available: differential protection of busbar, transformer and cable zones, arc fault protection of switch panels, zone and time-oriented protection, in various combinations. Read more..
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