CN-121984098-A - Method, device and system for controlling low voltage ride through of net-structured doubly-fed motor based on flux linkage inhibition and storage medium

CN121984098ACN 121984098 ACN121984098 ACN 121984098ACN-121984098-A

Abstract

The invention discloses a method, a device, a system and a storage medium for controlling low voltage ride through of a network-structured double-fed motor based on flux linkage inhibition, and belongs to the technical field of power generation, power transformation or power distribution. When the voltage of the power grid drops, the grid-built control unit is locked at first, the internal potential phase is obtained based on the virtual synchronous machine principle, the proportionality coefficient of the exciting magnetic chain ring is dynamically adjusted to maximize system damping and accelerate the attenuation of transient components of the stator flux linkage, a rotor current instruction is generated in real time according to the voltage and current capacity limit of the rotor-side converter on the basis, and a feedforward compensation strategy and a resonance controller are combined to output a modulation signal to drive the converter. According to the method, any hardware circuit is not required to be added, so that the over-current and over-voltage of a rotor in a fault period can be effectively restrained, the attenuation speed of a transient flux linkage is obviously improved, the reactive power supporting capability of a unit to a power grid is enhanced, and the high-performance low-voltage ride-through of the grid-formed double-fed motor is realized.

Inventors

YU WEIKE
CHEN WU
LI XIN

Assignees

东南大学

Dates

Publication Date: 20260505
Application Date: 20260121

Claims (10)

1. A method for controlling low voltage ride through of a net-structured double-fed motor based on flux linkage inhibition is characterized in that, When the power grid voltage drops, locking a grid control unit, locking a phase angle of an internal potential vector obtained by the last grid control unit before a fault occurs, calculating a rotor mechanical angle and a slip angle of the doubly-fed motor under the phase angle of the internal potential vector obtained by the last grid control unit before the fault occurs, acquiring a rotor current of the doubly-fed motor under an internal potential synchronous rotation coordinate system according to the slip angle, acquiring a stator current and a stator voltage of the doubly-fed motor under the internal potential synchronous rotation coordinate system according to the phase angle of the internal potential vector obtained by the last grid control unit before the fault occurs, increasing an excitation flux linkage proportional coefficient under the capacity constraint of a rotor side converter, assigning 0 to the excitation flux linkage integral coefficient, and acquiring a reference value of the rotor current; Calculating a rotor voltage feedforward compensation value according to rotor current, stator voltage and stator flux linkage of the doubly-fed motor under an internal potential synchronous rotation coordinate system, performing closed-loop regulation and resonance control on an error signal of the rotor current of the doubly-fed motor under the internal potential synchronous rotation coordinate system compared with a reference value, obtaining a rotor voltage control quantity, calculating a rotor voltage requirement value according to the rotor voltage feedforward compensation value and the rotor voltage control quantity, and generating a switching signal of a rotor side converter according to the rotor voltage requirement value.
2. The method for controlling low voltage ride through of a grid-built double-fed motor based on flux linkage suppression according to claim 1, wherein the method is characterized in that the excitation flux linkage proportionality coefficient is increased under the constraint of the capacity of a rotor-side converter according to the following specific steps of The excitation flux linkage scaling factor is iteratively updated, wherein, 、 Respectively the first Secondary, the first The excitation flux linkage ratio coefficient value calculated by the iteration, In order to synchronize the rotational angular velocity, For the stator inductance to be a function of the stator inductance, For the mutual inductance of the stator and the rotor, For the resistance of the stator, For sampling period, initial value of proportion coefficient of excitation flux linkage Is that , The maximum current-withstanding value of the rotor-side current transformer, As a voltage sag depth factor, , Is the stator terminal voltage amplitude.
3. The method for controlling low voltage ride through of a mesh-forming doubly-fed machine based on flux linkage suppression as claimed in claim 2, wherein said obtaining a reference value of rotor current comprises introducing a transition function pair The method comprises the steps of carrying out attenuation on a q-axis current reference value of a rotor at moment to obtain a q-axis current real-time reference value of the rotor, and carrying out closed-loop adjustment on an error of a d-axis excitation magnetic link to obtain a d-axis current reference value of the rotor.
4. A method for controlling low voltage ride through of a mesh-forming doubly fed machine based on flux suppression as claimed in claim 3 wherein said transition function is Real-time reference value of rotor q-axis current Is that , Is that The reference value of the q-axis current of the rotor at the moment, As the moment of occurrence of the fault The rotor q-axis current reference value, , = 。
5. The method for controlling low voltage ride through of a grid-formed doubly-fed machine based on flux linkage suppression according to claim 4, wherein the calculating of the feedforward compensation value of the rotor voltage according to the rotor current, the stator current and the stator voltage of the doubly-fed machine in the internal potential synchronous rotation coordinate system is specifically as follows: , wherein, 、 The feedforward compensation value is used for the d-axis and q-axis voltages of the rotor, In order to achieve a slip angle frequency, Is the leakage inductance coefficient of the magnetic resonance tube, For the inductance of the rotor, 、 The d-axis current and the q-axis current of the rotor of the doubly-fed motor under the internal potential synchronous rotation coordinate system, 、 Is the magnetic linkage of the d axis and the q axis of the stator, 、 The d-axis voltage and the q-axis voltage of the stator of the doubly-fed motor under the internal potential synchronous rotation coordinate system, 、 The stator d-axis and q-axis currents of the doubly-fed motor in the internal potential synchronous rotation coordinate system.
6. The method for controlling low voltage ride through of a grid-built double-fed motor based on flux linkage suppression according to claim 5, wherein the closed-loop adjustment and resonance control are performed on the rotor current of the double-fed motor under the internal potential synchronous rotation coordinate system compared with an error signal of a reference value, and the rotor voltage control quantity is obtained specifically as follows: Closed-loop adjustment is carried out on an error signal of the rotor q-axis current of the doubly-fed motor under the internal potential synchronous rotation coordinate system compared with a real-time reference value of the rotor q-axis current through proportional-integral resonance control, so as to obtain a rotor q-axis voltage control quantity; and extracting an alternating current component from a rotor d-axis current of the doubly-fed motor under an internal potential synchronous rotation coordinate system, performing closed-loop adjustment on an error signal of the rotor d-axis current alternating current component compared with a rotor d-axis current reference value through proportional-integral resonance control to obtain a rotor d-axis voltage alternating current component control quantity, and performing closed-loop adjustment on an error signal of the rotor d-axis current direct current component compared with a reference value 0 through proportional-integral control to obtain a rotor d-axis voltage direct current component control quantity.
7. The method for controlling low voltage ride through of a grid-built double-fed motor based on flux linkage suppression according to claim 6, wherein the rotor voltage demand is calculated according to the rotor voltage feedforward compensation value and the rotor voltage control amount, specifically: , wherein, 、 For the rotor d-axis and q-axis voltage demand, For the control amount of the d-axis voltage alternating current component of the rotor, For the control quantity of the d-axis voltage direct current component of the rotor, Is the rotor q-axis voltage control quantity.
8. The utility model provides a net-structured double-fed motor low voltage passes through controlling means based on magnetic linkage suppression which characterized in that includes: A rotor current instruction generating module, which is used for locking a grid control unit when the voltage of a power grid drops, locking the phase angle of an internal potential vector obtained by the last grid control unit before a fault occurs, calculating the rotor mechanical angle and the slip angle of the doubly-fed motor under the phase angle of the internal potential vector obtained by the last grid control unit before the fault occurs, obtaining the rotor current of the doubly-fed motor under an internal potential synchronous rotation coordinate system according to the slip angle, obtaining the stator current and the stator voltage of the doubly-fed motor under the internal potential synchronous rotation coordinate system according to the phase angle of the internal potential vector obtained by the last grid control unit before the fault occurs, increasing the proportional coefficient of an excitation flux linkage under the capacity constraint of a rotor side converter, assigning 0 to the integral coefficient of the excitation flux linkage, obtaining the reference value of the rotor current, And the modulation signal generation module is used for calculating a rotor voltage feedforward compensation value according to rotor current, stator voltage and stator flux of the doubly-fed motor under the internal potential synchronous rotation coordinate system, performing closed-loop regulation and resonance control on an error signal of the rotor current of the doubly-fed motor under the internal potential synchronous rotation coordinate system compared with a reference value, acquiring a rotor voltage control quantity, calculating a rotor voltage requirement value according to the rotor voltage feedforward compensation value and the rotor voltage control quantity, and generating a switching signal of the rotor side converter according to the rotor voltage requirement value.
9. A computer system comprising a memory and a processor, the memory having stored thereon a computer program that is executed on the processor, wherein the processor, when executing the computer program, performs the steps of the flux linkage suppression-based grid-built doubly-fed motor low voltage ride through control method of claim 1.
10. A computer readable storage medium having stored thereon a computer program, wherein the computer program when executed by a processor implements the steps of the flux linkage suppression based grid double feed motor low voltage ride through control method of claim 1.

Description

Method, device and system for controlling low voltage ride through of net-structured doubly-fed motor based on flux linkage inhibition and storage medium Technical Field The invention relates to a double-fed motor control and new energy grid-connection technology, in particular to a low-voltage ride-through control method, a device, a system and a storage medium for a grid-structured double-fed induction motor based on flux linkage inhibition when the voltage of a power grid drops, and belongs to the technical field of power generation, power transformation or power distribution. Background The doubly-fed induction motor has the characteristics of wide rotating speed range, excellent grid-connected performance, high cost efficiency and the like, and is currently applied in a plurality of fields in a large scale, and is mainly concentrated on a wind power generation system, a pumped storage system and a ship shaft belt power generation system. Taking a wind power system as an example, modern grid-connected specifications require that a wind turbine generator has low voltage ride through capability, i.e., maintains grid-connected operation during grid faults, and can provide reactive support to a grid within a specified time period. Likewise, pumped-storage systems also need to meet similar low voltage ride through requirements. The stator winding of the doubly-fed induction machine is directly connected to the grid, so that the doubly-fed induction machine is highly sensitive to the voltage fluctuation of the grid. During grid faults, the rotor side will generate extremely high induced electromotive forces, which in turn cause overvoltage and overcurrent faults. Therefore, the doubly-fed induction motor system has inherent defects of difficult rotor overcurrent and overvoltage suppression, slow transient flux linkage attenuation and insufficient reactive support capability of the unit during grid voltage sag. At present, a control strategy for improving excitation control of a rotor-side converter to improve low voltage ride through capability of a unit is widely paid attention to because the control strategy has the advantages of no need of adding any hardware and flexible control. At present, a few researches on improving the low voltage ride-through capability of a doubly-fed wind turbine generator set by improving a rotor-side converter excitation control method are carried out, namely ' symmetrical voltage drop down doubly-fed induction generator control ' is carried out, the free component of a stator flux linkage is tracked by controlling rotor current to accelerate the decay rate of the stator flux linkage, but huge rotor current is required, the transition depends on the converter capacity to influence the feasibility of a system ', the improved doubly-fed asynchronous generator low voltage ride-through control strategy in the power grid fault is carried out, virtual impedance is introduced into a de-excitation control method, the ride-through operation interval of the de-excitation control method is widened, but the method is only applied to a grid-following system and a phase-locked loop is required, the phase stability and the control robustness during grid faults are further weakened, the improved doubly-fed wind generator virtual synchronous generator control for overcoming the symmetrical voltage faults is carried out, the outer loop is a power loop, the inner loop is a grid-structured doubly-fed induction motor control strategy for exciting magnetic link, the decay of the transient component can be controlled through the feedback of the exciting flux linkage, the current limiting control is carried out and the exciting flux link control is carried out, the exciting flux linkage is additionally, the flux linkage is fed back, and the transient component is not used, and the transient component is also is mutually excited, the flux-fed flux control side has the maximum disturbance control effect is weakened, and the transient component is weakened. Disclosure of Invention The invention aims to provide a method, a device, a system and a storage medium for controlling low voltage ride through of a network-structured doubly-fed induction motor based on a flux linkage inhibition strategy aiming at the defects existing in the background technology, the invention aims to realize safe and stable operation of a grid-structured double-fed motor under fault conditions and provide reactive power support for a power grid rapidly by improving a low-voltage ride-through control strategy of a rotor-side converter so as to solve the technical problems that the current demand on a rotor is high, the phase locking precision is dependent, the rotor current is limited, and the flux linkage inhibition effect is weakened. The invention adopts the following technical scheme for realizing the purposes of the invention: a method for controlling low voltage ride through of a net-structured double-fed motor based on flux