Interleaved Soft Switching Hybrid Multilevel DC Interconnected Converter

Abstract

The invention proposes a cross-connection soft-switch hybrid multi-level direct current interconnection converter, which belongs to the technical field of medium and high voltage direct current transmission and distribution. The converter includes a bridge chopper, a power electronic capacitor bridge arm and two identical power electronic reactance bridge arms; the two bridge arms of the bridge chopper are respectively composed of two power electronic series switch groups connected in series; the bridge chopper The positive pole of the wave generator is connected to the high-voltage positive terminal of the converter, and the negative pole is connected to the high-voltage negative terminal of the converter; the positive pole of the capacitor bridge arm is connected to the high-voltage positive terminal of the converter, and the negative pole is connected to the high-voltage negative terminal of the converter; The positive poles of the reactance bridge arms are respectively connected to the midpoint of the two bridge arms of the bridge chopper, and the negative poles of the two reactance bridge arms are connected to the low-voltage positive terminal of the converter. The invention adopts the non-isolation method without transformer to realize the power conversion of different DC voltage levels, so that all the switching devices in the power electronic series switch group can realize zero-current conversion soft switching, and has high conversion efficiency, small loss, easy realization of dynamic voltage equalization and high efficiency. Economic cost advantage.

Description

technical field [0001] The invention belongs to the technical field of medium and high voltage direct current transmission and distribution, and in particular relates to an interleaved soft switch hybrid multi-level direct current interconnection converter, which has the capability of boosting and stepping down direct current conversion. Background technique [0002] At present, the power and voltage levels of high-voltage flexible direct transmission (VSC-HVDC) have reached hundreds of megawatts (MW) and hundreds of kilovolts (kV). From MW-level photovoltaic farms or DC integration of offshore wind power to the emergence of large-capacity DC energy storage systems and medium-voltage DC motor drives, there are interconnection requirements for DC transmission and distribution systems of different voltage levels. With the introduction of the concept of DC power grid, because it can meet the decentralized access of distributed energy sources and the demand for a large number of...

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Problems solved by technology

Among them, type 1) the current and voltage stress on the switching device is relatively large, and usually there is only one phase, resulting in large current ripple on the input and output sides, so it is not suitable for high-voltage and high-power applications; type 2) is the same as the isolated terminal pair Compared with the transformer capacity, the demand for the transformer capacity is reduced, and the utilization rate of the available capacity is also higher, but the loss is increased; type 3) the loss is lower, and the voltage and current stress are also smaller, but the IGBT used The number of devices and capacitors is large, and the cost is high

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