Alternating current and direct current mixed micro power grid comprising Z source converter and coordination control strategy

Abstract

The invention relates to an alternating current and direct current mixed micro power grid comprising a Z source converter and a coordination control strategy. The alternating current and direct current mixed micro power grid comprises a direct current part, an alternating current part and the Z source converter, wherein the direct current part is connected with the alternating current part through the Z source converter. Coordination control is adopted in a grid connection and island model, all converters in the whole micro power grid work in a coordinating and cooperation mode, and multiple control purposes can be realized. A designed controller enables the impedance of all the converters to be matched and guarantees stability of the micro power grid. As the voltage of a direct current bus is low, the power level of the direct current bus and the converter between a power source and a load is reduced, and loss is reduced, so that the alternating current and direct current mixed micro power grid is particularly suitable for the condition that the voltage of the direct current micro power source and the voltage of the direct current load are both low. In addition, the alternating current and direct current mixed micro power grid has the advantages of being flexible to control, high in reliability and the like.

Description

technical field [0001] The present invention relates to a micro-grid with a new structure and a control strategy, in particular to an AC / DC hybrid micro-grid including a Z-source converter and a coordinated control strategy. Background technique [0002] Microgrid solves the grid-connection problem of distributed generation. As a beneficial supplement to large power grid, microgrid has broad application prospects. At present, AC microgrid is the main form of microgrid, and the research is relatively more extensive and in-depth. In the AC microgrid, all micro power sources, energy storage devices and loads are connected to AC feeders, and they all go through multi-level power electronic converters such as DC-DC-AC, AC-DC-AC, AC-DC-DC, etc. To connect with the AC feeder, it is necessary to track the frequency and phase of the AC feeder, which reduces the controllability and reliability; in addition, similar to the large power grid, the flow and balance of reactive power must ...

AI Technical Summary

Problems solved by technology

In addition to the high DC bus voltage mentioned in point (1), the conventional AC / DC bridge converter must insert dead time in the driving signals of the upper and lower bridge arms to avoid direct short circuit caused by direct current, which not only causes The AC voltage or current waveform output by the converter is distorted, and more seriously, it reduces the reliability of the converter and threatens the safety of the microgrid

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