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Doubly-fed motor rotor string dynamic resistance low-voltage ride-through control method

A technology of low voltage ride through and dynamic resistance, which is applied in the direction of generator control circuit, control system, control generator, etc., can solve the problems that fixed resistance is difficult to meet the requirements of low voltage ride through, and the side is connected in series, so as to improve the low voltage ride through Good performance, enhanced stability, and dynamic performance

Active Publication Date: 2020-11-27
BAOJI UNIV OF ARTS & SCI +3
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0006] Aiming at the deficiencies of the prior art, the present invention provides a doubly-fed motor rotor series dynamic resistance low-voltage ride-through control method, which solves the problem that the existing doubly-fed motor rotor side is connected in series with a single, fixed resistance, which is difficult to meet different voltage drop depths. Low voltage ride through requirements

Method used

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  • Doubly-fed motor rotor string dynamic resistance low-voltage ride-through control method
  • Doubly-fed motor rotor string dynamic resistance low-voltage ride-through control method
  • Doubly-fed motor rotor string dynamic resistance low-voltage ride-through control method

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Experimental program
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Effect test

Embodiment 1

[0037] A low-voltage ride-through control method for doubly-fed motor rotor series dynamic resistance, according to the magnitude of the voltage drop and the threshold value of the rotor current, it is proposed to connect dual dynamic resistance R in series on the rotor side SDDR , R SDDR Divided into R rs1 and R rs2 , and flexibly switch between the two resistors according to the depth of the voltage drop and the magnitude of the rotor current when the low voltage crosses the LVRT, and use fuzzy control to design the switching strategy of the dual dynamic resistors, formulate a comprehensive rotor resistance input rule, and accurately control Resistance R rs1 or R rs2 input, see figure 2 , including the following steps:

[0038] S1. Determine the input and output variables of the system. The dual-resistor switching fuzzy controller adopts a dual-input and single-output structure to adjust the excess energy during LVRT. The input values ​​​​are respectively taken from th...

Embodiment 2

[0053] Using the low voltage ride-through control method of the rotor string dynamic resistance of the doubly-fed motor proposed in the first embodiment, such as Image 6 As shown, when the voltage drops slightly (grid voltage drops to 70%), R rs2 Putting into operation and the simulation test of the rotor crowbar protection, it can be seen that when the crowbar is protected, the maximum value of the LVRT rotor current is about 0.74pu, and the R SDDR The maximum value of the rotor current of the fuzzy control switching algorithm is reduced to about 0.7pu, and the transient oscillation process of the current is reduced; Figure 7 The DC bus voltage waveforms of the two methods are compared. It can be seen that the switching on and off of the crowbar protection destroys the steady-state power balance relationship between the grid-side converter and the rotor excitation converter due to the need to block the rotor side pulse, resulting in DC The transient process of the bus volt...

Embodiment 3

[0055] In order to verify the practical feasibility of the method described in Example 1, the DFIG rotor string dynamic resistance low voltage ride-through control method proposed in Example 1 was used to build a DFIG wind power generation simulation experiment platform based on the DSP28335 controller. The method described in Example 1, such as Figure 10 As shown, the flow chart of the experimental algorithm is given, Figure 11 with Figure 12 When the grid voltage drops to 20% and 80%, respectively, and the drop lasts for 720 ms, the rotor crowbar protection is compared with the experimental results of the method proposed in Example 1.

[0056] It can be seen that in Crowbar protection, due to the blockage of the rotor converter, the active power of the stator is almost reduced to 0. At the same time, DFIG operates as an ordinary asynchronous motor and needs to absorb a large amount of reactive power from the grid, resulting in a further drop in the grid drop voltage; In...

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Abstract

The invention discloses a doubly-fed motor rotor string dynamic resistance low-voltage ride-through control method, and belongs to the technical field of wind power generation control. According to avoltage drop amplitude and a rotor current threshold value, a rotor side is connected in series with a double dynamic resistor RSDDR, the RSDDR is divided into Rrs1 and Rrs2, the two resistors are flexibly switched according to the voltage drop depth and the rotor current when the low voltage passes through LVRT, a switching strategy of the double dynamic resistors is designed by adopting fuzzy control, a comprehensive rotor resistance input rule is formulated, and the input of the resistor Rrs1 or Rrs2 can be accurately controlled. According to the doubly-fed motor rotor string dynamic resistance low-voltage ride-through control method, a rotor series connection double-dynamic-resistor structure is adopted, according to different voltage drop depths, fuzzy control is adopted for controlling the switching strategy of the double dynamic resistors connected with the rotor in series, fuzzy control has the advantages of being good in dynamic performance and high in adaptability, the stability of a system can be effectively enhanced, and the low-voltage ride through performance is improved.

Description

technical field [0001] The invention belongs to the technical field of wind power generation control, in particular to a method for controlling dynamic resistance low-voltage ride-through of a doubly-fed motor rotor string. Background technique [0002] The stator side of the doubly fed induction generator (DFIG) is directly connected to the grid, which is not very resistant to the low voltage ride through (LVRT) caused by the grid fault voltage drop. The decommissioning of units due to improper control of low wear will seriously threaten the safety of the wind power industry chain. [0003] At present, the research on LVRT of DFIG mainly focuses on two aspects: 1) software: by improving the control strategy of the rotor excitation converter to suppress the rotor overcurrent in the LVRT process or to accelerate the attenuation of the transient flux linkage, in order to reduce Power and torque ripple. It is characterized by a strong dependence on system parameters, and when...

Claims

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Application Information

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IPC IPC(8): H02J3/38H02P9/00H02P101/15
CPCH02J3/381H02P9/007H02J2300/28H02P2101/15Y02E10/76
Inventor 张文娟马浩淼张飞鸽胡静波
Owner BAOJI UNIV OF ARTS & SCI
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