Triangularly connected chain H bridge suspended type inverter interphase DC side voltage balancing control method

Abstract

The invention discloses a triangularly connected chain H bridge suspended type inverter interphase DC side voltage balancing control method. The method is based on combination of zero sequence current injection and split phase control and comprises overall DC side voltage control, interphase DC side balancing control and phase DC side balancing control. Each phase modulating voltage output by the overall DC side voltage control is corrected via each phase modulating wave correction required by interphase balance output by the interphase DC side voltage balancing control, as a result, output voltage modulating wave of each phase is obtained, then the output voltage modulating wave of each unit is obtained via the phase DC side balancing control, and finally, pulse signals of each switch component are generated via a wave carrier phase-shifting PWM (Pulse-width Modulation) module. According to the method, three phases are comprehensively considered, the DC side balancing control is performed by adopting different methods under different conditions, and the method has great significance in application of large-scale network connection and large-scale energy storage of a triangularly connected chain H bridge network connecting inverter and matched renewable resources.

Description

technical field [0001] The invention belongs to the technical field of application of high-voltage and high-power power electronic technology in power systems, and relates to a chain-type H-bridge direct-mounted inverter DC-side voltage balance control method based on a phase-splitting control method and a zero-sequence current injection method. . Background technique [0002] In recent years, with the development of new energy, H-bridge cascade structure has become a research hotspot in the fields of grid-connected inverter, energy storage, power electronic transformer, etc. It is of great significance to enhance the stability of power system. [0003] This type of grid-connected inverter can be connected to the high-voltage power grid without a transformer. It is easy to realize modularization in structure, and has low switching loss and harmonic output. However, there are parallel-connected H-bridge DC sides in its structure. The difference of loss and mixed loss, the d...

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Problems solved by technology

There is research on the phase separation control method for STATCOM, but unlike STATCOM, the main output of the grid-connected inverter is active current, this method will cause serious three-phase current imbalance, thereby polluting the power grid

There is also a control method for injecting zero-sequence current in a delta structure, which can realize energy exchange between each single-phase chain-link inverter while maintaining a balance of three-phase phase currents, so as to achieve the purpose of DC side balance between phases , but the adjustment ability of this method is limited, and it does not take into account the influence of grid-side imbalance

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