Novel connection method of three-phase cascade convertor and working mode during power supply or load fault

Abstract

The invention provides an operation mode of a cascade input-cascade output convertor during a short-circuit load fault of an output end of the convertor by the traditional Y-Y connection method. In the operation control mode, stable operation of a three-phase unity power factor of an input end can be kept during a single-phase short-circuit load fault of the output end. The invention further provides a novel Y-Y connection method and an operation mode of the convertor during open-phase power supply of the input end and the short-circuit load fault of the output end by the novel connection method. With the adoption of the novel Y-Y connection method and the corresponding operation control mode, three-phase stable operation of the output end can be kept during the open-phase power supply of the input end of the convertor, and the stable operation of the three-phase unity power factor of the input end can be kept during the short-circuit load fault of the output end. The operation mode has beneficial effects of realizing fault-tolerant operation and fault isolation of the convertor, improving the power supply reliability, and reducing the economic loss caused by a power supply fault.

Description

technical field [0001] The invention belongs to the research field of application technology of high-voltage and high-power cascaded power electronic converters in electric energy conversion, and particularly relates to the technology of fault isolation and fault-tolerant operation at both ends of three-phase power electronic cascaded converters to improve power supply reliability. Background technique [0002] In recent years, cascaded multilevel power converters without industrial frequency transformers have attracted more and more attention due to their advantages of high efficiency, intelligence, and low pollution. And other fields have been more and more successful applications. At present, multi-level power converters without power frequency transformers can be divided into two types: power electronic transformers with two-way flow of energy, and frequency converters with one-way flow of energy; from the perspective of connection methods, they are mainly divided into c...

AI Technical Summary

Problems solved by technology

In the power distribution system, when the power supply network fails or the load has four common short-circuit faults, how to improve the wiring mode and control mode of the converter so that the system can maintain normal power supply to the non-fault phase and realize the normal balance of the non-fault end Stable operation, realizing fault isolation at both ends of the converter, fault-tolerant operation, thereby improving the reliability of power supply has not yet been proposed

Images