Control method of direct drive wind power system low voltage ride through

Abstract

The invention discloses a method for controlling low voltage ride-through of a direct-drive type wind power system. The method comprises the following steps that (1) load torque of an electric generator is changed through a machine side current transformer of a permanent magnet direct drive wind generation set so as to achieve maximum wind energy utilization; (2) under the situation of matching with a direct-current side unloading circuit, when a depth power grid fails, the aim of rapidly and smoothly adjusting the power grid is achieved through the combination of the control strategy that a grid-side current transformer runs in a reactive priority output mode and a reactive compensation circuit additionally arranged on a grid side; (3) a zero d-axis current control strategy is adopted in an electric generator side current transformer to adjust the electromagnetic torque output by the electric generator so as to adjust the rotating speed of the electric generator; (4) a power grid voltage oriented vector control strategy is adopted in the grid-side current transformer, double-loop control is adopted, an outer ring is a direct-current side voltage ring, the direct-current side voltage can be stabilized under the situation that the power grid is normal, the inner ring is a current ring, and the decoupling control over output of active power and reactive power is achieved.

Description

technical field [0001] The invention relates to a control method for low-voltage ride-through of a direct-drive wind power system, in particular to a control method for a low-voltage ride-through reactive power compensator of a direct-drive wind power system. Background technique [0002] According to the statistical report of the Global Wind Energy Association, by the end of 2010, the total installed capacity of wind power in the world reached 194,390 MW, and the power generation exceeded 409.9 billion kWh, accounting for 1.92% of the world's total power generation. Wind power is becoming more and more important to meet power demand. At present, my country is already in the golden period of wind power development. According to my country's "Twelfth Five-Year Plan", it is estimated that by the end of 2015, the total newly installed capacity of wind power will reach 90,000 MW. In the new energy technology revolution that emerged in the 1980s, grid-connected wind power genera...

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