Dynamic loads, such as high-energy sensors or energy based weapons, may be deployed on platforms including ships, planes, satellites, or the like. The dynamic loads may consume a large portion of the platform's electrical power resources and thereby cause extreme power transients. These extreme power transients may have dynamic load profiles, including both periodic predictable characteristics and aperiodic unpredictable characteristics. The dynamic load profiles may cause sudden changes in power at the platform's power distribution system. The sudden changes of power may be stressing to platform systems, including generators, prime movers, and other loads sharing a common bus of the power distribution system. Duty cycles of the dynamic loads may vary from small to continuous and, for some cases, the peak power demands may be above the capability of the platform's power plant. These types of extreme dynamic load profiles may not be supported with conventional power distribution systems.
Conventional power distribution systems have focused heavily on providing well-regulated voltages and clean power to a corresponding load. Typically, the voltage dynamics of the load may be minimized by minimizing the output impedance of each converter stage by using small series inductance values, large shunt capacitance values, and/or control loops with high bandwidths. However, conventional power distribution systems may do little to prevent the mid to low frequency load dynamics from propagating back to the distribution bus and generator.
In an instance in which the dynamic load profiles propagate back to the platform's electric plant, significant power quality issues and generator/distribution losses may occur. Additionally, dynamic pulse loading of a dynamic load profile may cause wear and tear on mechanical parts of the generator. Torsional stresses to the shaft of the platform's prime mover may result due to very large and quickly changing electromagnetic load torques. The dynamic electromagnetic load torques may also excite the shaft's torsional resonances, e.g. sub-synchronous resonances, adding additional stresses to the shaft.
In some examples, a power distribution system may be buffered from dynamic load profiles by a brute force method, a throw away power method and/or a restricted-timeline method. In an example power distribution system utilizing the brute-force method, passive filters may be used to smooth the dynamics of the dynamic load profile. Although the brute force method results in minimal additional power losses, achieving the smoothing and/or filtering desired by the platform power system may require filter sizes and/or weights that are impractical or prohibitive for platform, such as a ship, installation.
In an example power distribution system utilizing the throw-away-power method, when the load is not using the maximum power allocated, the excess power is dissipated in an active load. This type of power distribution system may increase the reliability of the generator and minimize bus disturbances by maintaining a constant load profile to the generators. However, the active load may have severe impacts on power distribution system efficiency resulting from the large additional power dissipation, increasing both cooling requirements and fueling costs for the platform.
In an example power distribution system utilizing the restricted-timeline method, the power distribution system may include a predefined charging time for the power distribution system. Pulse power may only be supplied by the power distribution system to the load at predefined scheduled time intervals. For these power distribution systems, the successive power pulses, e.g. launch times or fire times (repetition rate) and corresponding system performance are limited by the charging times of the power distribution system. Some examples of such systems include the Electromagnetic Aircraft Launch System (EMALS) and rail guns.
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