Starting method suitable for solid-state transformer

Abstract

The invention discloses a starting method suitable for a solid-state transformer. According to the starting method suitable for the solid-state transformer, a system is pre-charged through a low-voltage side; the energy needed in starting all comes from a low-voltage direct current source; after a starting condition is satisfied, grid-connection operation is performed; by adoption of the starting method for the solid-state transformer, introduction of soft starting matched equipment is not required; instead, control can be performed by fully depending on device characteristic of the system, so that stable and impact-free starting of the system can be realized; and meanwhile, an impact current to the equipment and a power grid in the starting process also can be suppressed.

Description

technical field [0001] The invention belongs to the technical field of power electronic transformers, and relates to a method suitable for starting a solid-state transformer. Background technique [0002] The present invention relates to the application of power electronic transformer (PET-PowerElectronic Transformer) / solid-state transformer (SST-Solid State Transformer) in the field of high-voltage photovoltaic grid-connection, which can be called a high-voltage photovoltaic grid-connection inverter when applied to the field of photovoltaic grid-connection , can replace the overall grid-connected solution of traditional photovoltaic inverter + step-up transformer, and has the advantages of low standby loss, high system efficiency, and high degree of intelligence. Chinese patent 201610222409.7 introduces the high-voltage photovoltaic grid-connected power generation system based on solid-state transformer array in detail. [0003] The solid-state transformer adopts a cascade...

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Problems solved by technology

[0004] This kind of cascade topology is mostly seen in flexible DC transmission and SVG. The capacitor voltage on the high-voltage side of the module is pre-charged through the series soft-start resistor on the high-voltage side. Since the module is charged by the AC line voltage on the high-voltage side, it cannot be charged to the high-voltage side. The capacitor voltage required for grid connection, at this time there will be an inrush current for grid connection

For solid-state transformers, the voltage on the low-voltage DC input side is determined by the connected equipment, and there may be a large voltage difference from the high-voltage side voltage. If the dual active bridge is controlled to enter the normal operation mode at this time, there will be A large current impact may trigger the overcurrent protection inside the module, and even cause damage to the switch tube of the module

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