DFIG (Doubly Fed Induction Generator) based direct current grid-connection generating system and control method thereof

Abstract

The invention discloses a DFIG (Doubly Fed Induction Generator) based direct current grid-connection generating system which comprises multiple DFIGs and a direct current power grid, wherein each DFIG is connected with a stator converter and a rotor converter; the stator converter and the rotor converter are connected with a controller; the stator converter has the functions of converting an alternating current outputted by the DFIG into the direct current while realizing the maximum wind energy tracking running of the DFIG; and the rotor converter has the functions of supplying excitation to a DFIG rotor while realizing the stable voltage control of a DFIG stator end. According to the DFIG based direct current grid-connection generating system, alternating current transmission is changed into direct current transmission for the power by directly utilizing the stator converter; the quantity of the converter is not increased; only the capacity of the stator converter is greater than the capacity of a network-side converter of a traditional DFIG wind power system; and meanwhile, the fluctuation of the voltage at the DFIG stator end does not need to be considered, so that the system structure is simple and the running property is stable; and the control for the DFIG and direct current transmission is simplified.

Description

technical field [0001] The invention belongs to the technical field of wind power grid-connected power generation, in particular to a DC grid-connected power generation system based on DFIG (double-fed asynchronous wind generator) and a control method thereof. Background technique [0002] With the increase of population and the development of economy, human beings' demand for energy is also increasing, and the traditional energy reserves are becoming increasingly exhausted, thus bringing about the problem of energy shortage. With the depletion of traditional energy sources, wind energy has become a very promising new energy source. In today's society, the wind power industry has become a pillar industry in the field of new energy sources. [0003] With the wide application of onshore wind farms, offshore wind farms are also developing continuously. Compared with onshore wind farms, offshore wind power has become an important sustainable energy source due to its advantages ...

AI Technical Summary

Problems solved by technology

This grid-connected system must use the sending end station to change the DFIG output power from AC transmission to DC transmission, and the sending end station needs to maintain a stable motor stator terminal voltage under different working conditions. The system structure is complex and the control is difficult.

In addition, domestic research on the DC grid-connected system of DFIG wind farms mostly simplifies the wind farm into a simple power source for analysis, and does not specifically design its topology in combination with DFIG's own characteristics. Field-grid research brings great limitations

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