Solid-state transformer with alternating current-direct current fault continuous operation capability and control method

Abstract

The invention proposes a solid-state transformer with an alternating current-direct current fault continuous operation capability and a control method. A hybrid modular multi-level converter bridge arm consists of a half-bridge sub-module and a full-bridge sub-module; the half-bridge sub-module and the full-bridge sub-module are interconnected with input ends of isolated dual active bridge converters through a sub-module direct current capacitor; output ends of multiple isolated dual active bridge converters are connected in parallel to form a low-voltage direct current bus; and the low-voltage direct current bus is connected to a three-phase full-bridge inverter. The solid-state transformer provided by the invention can provide a medium-voltage direct current port, a medium-voltage alternating current port, a low-voltage direct current port and a low-voltage alternating current port, so that multi-voltage-grade and multi-form alternating current-direct current hybrid power distribution network interconnection can be realized; the solid-state transformer has the alternating current-direct current fault continuous operation capability, quick switching of device operation modes whena short circuit or open circuit fault occurs on a network connected to any port can be realized, and continuous operation between non-faulty ports can be ensured, thereby improving the power supply reliability of the alternating current-direct current hybrid distribution network.

Description

technical field [0001] The present invention relates to the fields of intelligent distribution network technology and power electronics technology in power systems, and specifically relates to a hybrid modular multi-level solid-state transformer topology with uninterrupted operation capability for AC and DC faults and the control of the solid-state transformer method. Background technique [0002] Renewable energy is often connected to the distribution network in the form of distributed power and converted into electrical energy for end users. However, the operation mode of the traditional distribution network is basically based on the supplier-led, one-way radial power supply, and its power distribution primary control equipment (on-load voltage regulator, contact switch, etc.) And the high-precision real-time operation optimization requirements of the distribution network when the load fluctuates frequently. With the continuous increase of distributed power access, the r...

AI Technical Summary

Problems solved by technology

The first challenge comes from the relay protection technology of distribution network

At present, the relay protection technology of the AC power grid is relatively mature, and the protection difficulty is low; however, the relay protection technology of the medium and high voltage DC distribution network is not yet mature, and the protection difficulty is relatively high. Currently, the converter topology with DC fault blocking capability is adopted More effective DC fault handling scheme

The second challenge comes from the power supply reliability of the distribution network

However, this topology does not consider the ability to respond to medium and low voltage AC and DC faults, and cannot realize the uninterrupted operation of the non-faulty port of the device when the network connected to a certain port fails, which in turn affects the power supply reliability of the distribution network.

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