Improved low-voltage ride-through control system

A low-voltage ride-through and control system technology, applied in control systems, vector control systems, control generators, etc., can solve problems such as increasing the operating frequency range of fans and enhancing the robustness of fan operating systems, so as to increase the operating frequency range , solve the problem of low-voltage ride-through, and improve the effect of accuracy

Inactive Publication Date: 2019-10-15
HARBIN UNIV OF SCI & TECH
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0004] The present invention overcomes the deficiencies of the above-mentioned prior art, and provides an improved low-voltage ride-through control system that not only solves the low-voltage ride-through problem of the doubly-fed wind power generation system when the power grid fails, but also increases the frequency range of the fan operation and enhances the fan operation. The robustness of the system, using TSC, solves the reactive power demand problem of the doubly-fed induction motor during asynchronous operation;

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specific Embodiment approach 1

[0053] An improved low-voltage ride-through control system, such as figure 1 As shown, it includes a three-phase grid 1, a reactor 5, a rotor-side converter 7, a grid-side converter 8, a TSC circuit 9, a grid-side transformer 11, a doubly-fed induction motor 12, a DC capacitor 13 and a main control module 16; The TSC circuit 9 is a thyristor switching capacitor circuit, the three-phase power grid 1 is respectively connected with the reactor 5, the grid-side transformer 11, the doubly-fed induction motor 12 and the detection module, and the reactor 5 is sequentially connected with the TSC circuit 9 and the mains. The control module 16 is connected, the DC capacitor 13 is connected with the detection module, the output end of the main control module 16 is connected with the rotor-side converter 7, the grid-side converter 8 and the active crowbar protection circuit 10 respectively, the rotor The side converter 7 is respectively connected to the doubly fed induction motor 12 and t...

specific Embodiment approach 2

[0061] An improved low-voltage ride-through control system, a low-voltage ride-through reactive power compensation method, and a novel flux linkage observer control for a rotor-side converter based on the improved low-voltage ride-through control system described in the first technical solution, comprising the following steps:

[0062] Step a1, the three-phase power grid is energized, and the three-phase power grid operates normally;

[0063] Step a2, judging in real time whether the voltage of the three-phase power grid has a sag fault, if so, go to step a3;

[0064] Step a3: Collect the current and voltage of the three-phase power grid when the fault occurs through the detection module; detect whether the stator current of the doubly-fed induction motor increases sharply;

[0065] In step a4, the voltage and current collected during the fault are sent to the main control module, and the active crowbar protection circuit is connected to cut off the side of the rotor converter...

specific Embodiment approach 3

[0070] A novel flux linkage observer control method based on the second step a6 of the specific embodiment, such as Figure 4 to Figure 6 shown, including the following steps:

[0071] Step b1, according to the working principle of the doubly-fed induction motor (12), the basic equation of the voltage flux linkage of the rotor and the stator is obtained, as follows:

[0072]

[0073] Step b2, the rotor flux linkage calculation expression based on the voltage model in the two-phase stationary coordinate system (α, β axis system):

[0074]

[0075] After the rotor flux linkage is oriented, the rotor flux linkage can directly pass through the stator current. The d-axis current in the rotor flux linkage coordinate system is:

[0076]

[0077] Step b3, obtain the rotor flux linkage ψ through the current model αβr-i , the rotor flux linkage ψ is obtained through the voltage model αβr-u , ψ αβr-i Low pass filtering with ψ αβr-u After high-pass filtering, the superpositi...

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Abstract

Provided is an improved low-voltage ride-through control system. A novel flux observer is used to control the rotor side, and an active crowbar protection circuit and low-voltage ride-through reactivepower compensation are combined. When the grid voltage drops, the over-current and over-voltage on the rotor side and on the stator side will damage power devices and affect the stable operation of the system. The control by the novel flux observer works in a current mode at low frequency and works in a voltage mode at high frequency, which increases the operation frequency of a doubly fed induction motor. The novel observer contains an adaptive speed observer, which can improve the accuracy of rotor flux voltage and enhance the robustness of the system. The crowbar protection circuit is usedto solve the low-voltage ride-through problem of a doubly fed wind power generation system in case of grid fault. By employing a thyristor switched capacitor (TSC) circuit, the reactive power demandproblem of the doubly fed induction motor during asynchronous operation is solved.

Description

technical field [0001] The invention belongs to the technical field of wind power generation, and in particular relates to an improved low-voltage ride-through control system, a low-voltage ride-through reactive power compensation method and a novel flux linkage observer control of a rotor-side converter. Background technique [0002] With the rapid development of the current economy, human demand for energy is increasing year by year, and energy is an important material basis for human survival and development. Common energy sources are gradually decreasing, such as coal, oil and natural gas, and some energy sources are inconvenient to exploit At this time, wind energy is the best choice for new energy. As a new energy, wind energy has the characteristics of inexhaustible, inexhaustible and renewable energy. The most important wind energy is non-polluting energy. This makes wind power generation the hottest new energy power generation technology at present, and it is also ...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): H02J3/38H02J3/50H02P21/13H02P21/26H02P21/28
CPCH02J3/386H02J3/50H02P21/13H02P21/26H02P21/28Y02E10/76
Inventor 李文娟马亮亮李玖云
Owner HARBIN UNIV OF SCI & TECH
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