A dfig wind power system low voltage ride through control method based on static bifurcation control sgsc

Abstract

The invention relates to a low voltage ride through (LVRT) control method for a doubly fed induction generator (DFIG) wind generating system of a series grid-side converter (SGSC) based on static bifurcation control, which comprises the following steps of: (1) performing topological modeling; (2) realizing the low voltage transition of a DFIG by controlling the output voltage of the SGSC; (3) selecting a doubly fed generator parameter, and simplifying to obtain a topological structure of the wind generating system equivalently; (4) determining the state variable, input variable and output variable of the system, and detecting the voltage and current of a stator at the end of the generator; (5) solving a static bifurcation point; (6) reducing active power output by the generator according to the drop degree of power grid voltage in the failure process so as to fulfill the aim of inhibiting voltage drop; and (7) turning on an insulated gate bipolar transistor (IGBT) switch, and merging an energy-consuming resistor into a direct-current side to inhibit direct-current link voltage from rising and realizing the LVRT operation of the system when a power grid has voltage drop failure.

Description

(1) Technical field: [0001] The present invention relates to the field of wind power system control, in particular to a DFIG (Doubly Fed Induction Generator, double-fed asynchronous generator) wind power system low voltage based on static bifurcation control SGSC (Series Grid-side Converter, series grid side converter) Traverse control method. (two) background technology: [0002] In recent years, with the increasing proportion of wind power installed capacity in the power system, the impact of wind farm operation on system stability has attracted more and more attention, and specific requirements have been put forward for wind power grid integration, among which The low-voltage ride-through capability of wind turbines is one of them. Take effective low voltage ride through (Low Voltage Ride Through, LVRT) control measures to maintain the stability of the wind farm grid. Since the stator side of DFIG is directly connected to the grid, the rotor of the generator will easily...

AI Technical Summary

Problems solved by technology

Since the generator operates as an asynchronous motor during a fault, it will absorb reactive power from the grid, so the generator cannot participate in the system power regulation during the fault process, and cannot meet the reactive power requirements of the grid operating regulations. Poor voltage stability

On the other hand, when the Crowbar protection mode is adopted after a fault, the electromagnetic torque of DFIG is uncontrollable and fluctuates violently

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