Double-fed wind turbine generator converter control method used for flexible direct current power transmission system

Abstract

The invention relates to a double-fed wind turbine generator converter control method used for a flexible direct current power transmission system, and belongs to the technical field of wind power generation. According to the method, a double-fed wind turbine generator is controlled through a converter topology structure comprising a stator side converter, a machine side converter and a grid side DC-DC converter. The method includes the steps that firstly, the grid side DC-DC converter is controlled to work in the direct current voltage reduction state, so that the voltage of a direct current power gird is reduced to a proper level and kept constant; secondly, three-phase inversion is achieved by controlling the machine side converter; thirdly, the machine side converter is controlled after a draught fan is started so that the output frequency of the draught fan changes according to the change of the rotating speed of the generator and according to a fixed proportion; fourthly, the stator side converter is controlled to conduct rectifying and boosting so that maximum power point tracking and power factor correction can be achieved; fifthly, the grid side DC-DC converter is controlled to work in the direct current boosting state so that wind turbine generator flexible direct current power transmission and grid-connected power generation can be achieved. The method is particularly beneficial for popularizing and using the double-fed wind turbine generator in the flexible direct current power transmission system.

Description

technical field [0001] The invention relates to a control method, in particular to a control method used in a doubly-fed wind power generator converter of a flexible direct current transmission system, and belongs to the technical field of wind power generation. Background technique [0002] At present, the technical solutions for grid-connection of large-scale wind farms are mainly traditional AC grid-connection. [0003] In recent years, flexible DC transmission technology has attracted much attention due to its advantages of reliable operation, simple control, and low cost. There are generally three types: ① Generator centralized control grid connection based on flexible DC transmission, ② Generator decentralized control grid connection based on flexible DC transmission, ③ Distributed DC bus grid connection based on flexible DC transmission. [0004] The first two schemes ① and ② are the same as the traditional AC grid-connected technology schemes, and their common fea...

AI Technical Summary

Problems solved by technology

Its disadvantages are: step-up transformers and box-type substations are required, which occupy a large area and have high losses, which especially restrict the development of offshore wind power.

Although it does not require a step-up transformer, the above-mentioned wind turbines are all permanent magnet direct drive type, and the more widely used doubly-fed wind turbines have not been found in domestic and foreign reports because of their control complexity. application, seriously restricting the use and promotion of flexible direct current transmission technology in wind farms using doubly-fed wind turbines

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