Permanent magnetic direct-drive type offshore wind power plant grid-connected system topology structure and control method thereof

Abstract

The invention discloses a permanent magnetic direct-drive type offshore wind power plant grid-connected system topology structure and a control method thereof. A grid-connected system comprises a DC bus current collection type wind power plant, a wind field network-side converter station, a dual-stage boost transformer, an offshore rectification station, a seabed DC cable, a shore inversion station, a grid-connected side boost transformer and a land power grid which are successively connected, wherein the DC bus current collection type wind power plant employs a DC bus current collection topology structure and comprises multiple groups of wind turbines which are successively connected, a permanent magnetic synchronous generator, a machine-side rectifier and a DC bus for current collection. The control method is that the machine-side rectifier employs dual-closed-loop control of a rotating speed outer loop and a current inner loop, the wind field network-side converter station employs dual-closed-loop control of a voltage outer loop and the current inner loop, the offshore rectification station employs control of fixed AC voltages and fixed frequencies, and the shore inversion station employs dual-closed-loop control of fixed DC voltages and fixed reactive power. According to the invention, multi-machine parallel-connected operation can be realized, the electric energy conversion efficiency is improved, and the grid-connected AC harmonic quantity is reduced.

Description

technical field [0001] The invention relates to a grid-connected system of an offshore wind farm, in particular to a permanent magnet direct drive type offshore wind farm grid-connected system topology and a control method thereof, belonging to the field of wind power grid-connected. Background technique [0002] Offshore wind energy has many advantages such as high wind speed, stable wind force and less interference. Therefore, vigorously developing offshore wind power has become a new trend in the development of wind power. At present, because permanent magnet direct drive synchronous wind turbines have many advantages such as no gearbox, good reliability and high efficiency, they are increasingly used in megawatt-scale offshore wind turbines. [0003] For offshore wind farms built by permanent magnet direct-drive synchronous wind turbines, the grid-connected topology includes not only the internal power collection topology of the wind farm, but also the grid-connected tra...

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Problems solved by technology

[0004] At present, the AC bus current collection topology is generally used in wind farms, but its power conversion efficiency is low. Since each wind turbine has an independent control system, the control system of the entire wind farm is relatively more complicated; offshore wind farms are not The grid method generally adopts AC transmission (HVAC) grid connection, and the AC transmission grid connection method has a simple structure, low cost, and mature technology, but the transmission capacity and transmission distance are limited.

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