A DC voltage preset control method and application of a voltage source converter

Abstract

The invention discloses a DC voltage preset control method and application of a voltage source converter. At a steady-state operation stage before a DC fault, a DC voltage preset control instruction value of a DC voltage controller is a rated value set by a converter station station-stage controller. During the period of the DC fault, the converter station station-stage controller switches the DCvoltage preset control instruction value from the rated value to a newly added control reference quantity after detecting the fault, wherein the newly added control reference quantity comprises a converter station bus voltage and / or DC voltages of all DC lines connected with the DC bus. The converter station station-stage controller takes the DC bus voltage or the minimum value of the DC bus voltage and the voltages of the DC lines as a target voltage preset control instruction value during the fault. After the DC fault is eliminated, the voltage preset control instruction value is switched from the target voltage preset control instruction value to the rated value. The method can reduce the impact on the transient stability of an AC power grid from a DC grid fault.

Description

technical field [0001] The invention belongs to the field of electric power transmission and distribution, and more specifically relates to a DC voltage preset control method of a voltage source converter and its application in a flexible DC transmission system. Background technique [0002] Flexible DC grid technology has a good application prospect in the collection, transmission and grid connection of large-scale renewable energy. For my country, due to the large-scale development and utilization of wind power and photovoltaics, the technical demand for flexible DC power grids using overhead lines is more urgent. Compared with cable lines, the probability of short-circuit faults on overhead lines is greatly increased. [0003] In a two-terminal or multi-terminal flexible DC transmission system, the voltage control command value of the DC voltage converter station (referred to as the voltage station) before and after the DC fault is always kept at the rated value. Due to...

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Problems solved by technology

[0005] Aiming at the above defects or improvement needs of the prior art, the present invention provides a DC voltage preset control method and application of a voltage source converter, thereby solving the problem of the DC power of the converter station during the power recovery period after the DC fault is cleared. / DC current controller will be saturated, resulting in longer DC power recovery time, worsening the technical problem of transient stability of the DC grid external AC grid

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