Method for controlling triple line-voltage cascaded (LVC) converter based on equivalent circuit model

Abstract

The invention discloses a method for controlling a triple line-voltage cascaded (LVC) converter based on an equivalent circuit model. The method comprises the following steps of: 1) performing carrier phase-shifting space vector pulse width modulation; 2) establishing a triple LVC voltage source converter (VSC) equivalent switching circuit model; and 3) designing a triple LVC converter control system based on an equivalent switching circuit model, and constructing the triple LVC converter control system based on an equivalent switching circuit mathematical model under a d-q two-phase rotating coordinate system, which is established in the step 2), wherein design of the control system comprises design of a voltage control outer ring, design of a voltage-equalizing compensation control ring and design of a current control inner ring. The method has the advantages that computation resources are saved, the design difficulty of a controller is reduced, and realization of closed-loop control is facilitated; equalization of each direct current voltage is ensured, and a voltage-equalizing mode is simple in control and convenient in computation; and the reliability of the system is improved, and the content of harmonics in grid current is reduced.

Description

technical field [0001] The invention relates to a triple line voltage cascaded converter. In particular, it relates to a control method for a triple line voltage cascaded converter based on an equivalent circuit model with a three-phase two-level converter as a cascaded unit. Background technique [0002] With the widespread use of renewable energy and the increase in the output power level requirements of distributed power generation, the research on high-power converters has gradually become a hot topic in recent years. The traditional six-switch transistor three-phase two-level power conversion device can no longer meet the requirements of current converter devices due to its own conditions, and some new topologies of power conversion devices have emerged as the times require. Many of these new topological structures have adopted multi-level technology, multiplexing theory, etc., and new theoretical and technical problems have gradually emerged. Among them, cascaded mul...

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Problems solved by technology

However, multiple power converters are often composed of multiple circuit units, and the converter is also composed of three VSC circuit units; therefore, if the control system is independently designed for each component unit, the structure of the control system will be relatively complex. Complexity, high hardware cost, and the need to consider the coordinated operation between sub-control systems, it is difficult to achieve closed-loop control; therefore, it is necessary to design a control structure for the triple line voltage cascaded converter A control method that can adjust the operating status of each unit

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