Kongzhi Yu Xinxi Jishu (Jun 2023)
Optimization Design and Performance Research for Solid-state Bus-tie Switch of Marine DC Grid
Abstract
Marine DC power grid typically sustains high current when shorted and its electric characteristics are extremely susceptible to influence by the stray parameters. Given the limitations of cabin space, it is necessary for the bus-tie switch of the DC grid to be miniaturized and in a symmetrical topology while the same level of fault shutdown protection performance is maintained. To this end, this paper presents the rule that how support capacitors and busbar's stray parameters impact short-circuit current, which was analyzed through a combination of simulation and testing at multiple operating points of a typical DC power grid. Specifically, to ensure the safety of devices, breaking time of the solid-state circuit breaker should not exceed 200 μs, and addressing the transient overvoltage suppression in case of bus- tie switch breaking is identified as a key technical issue. Based on the analysis results, it proposes a solid-state circuit breaker with a mirror-symmetrical bus-tie switch topology suitable for marine application scenarios and with the optimized performance based on simulation, to integrate the bus-tie switch and chopper multiplexing as a solution for voltage oscillation upon the bus-tie switch breaking-off. Based on the practical short-circuit tests, it is verified that the designed bus-tie switch is capable of meeting continuous DC power supply conditions on the normal side DC power grid when the busbar and branch are short-circuited. The onboard test results show that the solid-state circuit breaker can achieve a breaking-off capacity in the order of 100 μs, the optimized design of bus-tie switch topology meets the short-circuit protection requirements of marine DC power grid, and the delay for the bus-tie switch to break-off in case of short-circuit fault can mitigate breaking overvoltage fluctuation, thus better guaranteeing system safety.
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