Two-level VSC current converter inter-pole short-circuit switch characteristic fault positioning method

Abstract

The invention discloses a two-level VSC current converter inter-pole short-circuit switch characteristic fault positioning method, and belongs to the technical field of the flexible DC grid control and protection. The method comprises the following steps: analyzing an AC feed physical process of a two-level VSC current converter under a DC side inter-pole short-circuit working condition in detail,and dividing the physical process into three stages according to a switch-on condition of an internal bridge arm in the current converter; estimating the approximate time interval, of firstly accomplishing the commutation from the occurrence of the fault, of the current converter by deriving the change rate limitation of the AC feed current at each stage; and on this basis, dividing a DC line into different fault sections according to the association of the internal bridge arm switch condition and the fault position electric distance. The own feed commutation physical process is clearly clarified after the current converter inter-pole fault occurs, the different fault sections can be approximately corresponded by only utilizing the current converter switch information, thereby providing anew path for the future development of the protection and fault positioning principle of the flexible DC grid.

Description

technical field [0001] The invention belongs to the technical field of flexible direct current power grid control and protection, and in particular relates to a fault location method for short-circuit switching characteristics between poles of a two-level VSC converter. Background technique [0002] With the increasing energy crisis and environmental pollution problems, vigorously developing renewable energy has become the only choice to solve the contradiction between resources and the environment. However, most of the electric energy generated by renewable energy cannot be directly integrated into the grid. As the interface between renewable energy and the grid, the converter plays the role of electric energy conversion and power transmission. Among various types of converters, two-level VSC converters are widely used in photovoltaic power plants, wind farms and other occasions that require power conversion due to their simple topology and low cost. The two-level VSC conv...

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Problems solved by technology

The uncontrollable switching behavior of the converter itself also prevents the electrical quantities in the circuit from being represented by a continuous differential equation, making it difficult to analyze the fault current

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