Self-adaption nonlinear control method for megawatt medium-voltage medium-frequency three-level direct-current converter

Abstract

The invention relates to a control method for a power electronic electric energy conversion device, in particular to a self-adaption nonlinear control method for a megawatt medium-voltage medium-frequency three-level direct-current converter. The control scheme of the method is mainly used for completing a voltage stabilization output function and a short circuit current limiting function to achieve the capacity to adapt to backward stage load change disturbance and the capacity for short circuit fault protection. A controller divides system states into a CCM steady state, a DCM steady state and a dynamic state, and when the three states are switched over, parameter self-adaption adjustment is carried out, and therefore excellent voltage stabilization output dynamic performance and static performance are obtained. The controller can overcome the defect that a traditional control method cannot obtain both voltage stabilization output dynamic performance and static performance and different working modes, and the advantages that ripple waves are small in the steady state and voltage fluctuation is small and recovery time is short in disturbance are achieved to the maximum extent.

Description

technical field [0001] The invention relates to a control method of a power electronic power conversion device, in particular to an adaptive nonlinear control method suitable for a megawatt-level medium-voltage medium-frequency three-level DC converter. Background technique [0002] The megawatt-level medium-voltage medium-frequency three-level DC converter can convert medium-high voltage direct current into low-voltage direct current, and realize the electrical isolation between the medium-high voltage direct current grid and the low-voltage direct current grid. With the wide application of direct current in land power systems and independent power systems such as locomotives, ships, and islands, megawatt-level medium-voltage intermediate-frequency three-level DC converters have broad market prospects. Its research results can also be extended and applied to distributed power generation in power systems, smart grids, clean energy and other occasions, with potentially huge s...

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Problems solved by technology

[0011] Therefore, it is difficult for the traditional PI control scheme to adjust a set of fixed controller parameters to meet the steady-state and dynamic performance of the system under different load levels. If a compromise is made, a part of the controller performance must be sacrificed, which is obviously not what is expected.

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