Design method for VSC-HVDC (Voltage Source Converter based High Voltage Direct Current) SMCC (Sliding Mode Current Control) based on combined reaching law

Abstract

The invention belongs to the field of power system control, aims at a problem of stability of a VSC-HVDC (Voltage Source Converter based High Voltage Direct Current) power transmission system, and analyzes influence of vector control on the VSC-HVDC system. For the existing instability phenomenon, an inner ring vector current control of a VSC-HVDC is designed under SMCC (Sliding Mode Current Control) based on a reaching law. Meanwhile, for the defect of large steady state buffeting of the SMCC based on an index reaching law, the invention discloses an SMCC strategy based on a combined reachinglaw, which is applicable to the VSC-HVDC, and analyzes influence of the strategy on small disturbance stability of the system. Finally, a simulation model of the VSC-HVDC is set up in PSCAD / EMTDC, and the designed SMCC strategy based on the combined reaching law is subjected to simulation verification. A result shows that compared to the SMCC based on the index reaching law, the designed SMCC based on the combined reaching law reduces buffeting in a steady state; meanwhile, influence of the SMCC on small disturbance stability of the system can be equivalent to a proportional element of whichan inner ring proportionality coefficient is changed along with time; and a phenomenon of unstable oscillation of the system, which is caused by a small inner ring proportionality coefficient of conventional vector control, can be eliminated.

Description

technical field [0001] The invention belongs to the field of power system control, and in particular relates to a VSC-HVDC sliding mode current control design method based on combined reaching law. Background technique [0002] With the increasing shortage of land resources such as power transmission corridors and the rapid development of renewable energy power generation, voltage source converter based high voltage direct current (VSC-HVDC) power transmission technology has been applied worldwide To the grid connection of renewable energy power generation, multi-terminal direct current transmission and other fields. In recent years, the construction of flexible direct current transmission projects has been rapid, and the stability analysis and control of VSC-HVDC will become an important issue affecting the safe and stable operation of power systems. [0003] In view of the above problems, in the stability analysis of VSC-HVDC, the current research finds that when the VSC ...

AI Technical Summary

Problems solved by technology

However, the current research on the VSC-HVDC sliding mode controller has not analyzed the influence of the SMC on the stability of the small disturbance of the DC transmission system, nor has it adopted an effective weakening scheme for chattering

At the same time, the difference between the vector inner loop current control link and the SMCC link of VSC-HVDC on the stability of the small disturbance of the system needs further research

Therefore, in view of the large chattering deficiency of the currently proposed VSC-HVDC sliding mode control, the present invention proposes a sliding mode current control design method that can reduce chattering, and analyzes the small disturbance stability of the system by the proposed design method The influence of control parameters and the influence of control parameters on system characteristics have certain practical application value

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