CN-121995282-A - Dynamic alternating current loss analysis method for high-temperature superconductive rotor magnet

CN121995282ACN 121995282 ACN121995282 ACN 121995282ACN-121995282-A

Abstract

The invention discloses a dynamic alternating current loss analysis method of a high-temperature superconductive rotor magnet, which uses a discrete sampling value of an excitation current time sequence as a unique input quantity, and loss energy uses quasi-static electromagnetic energy dissipation as a definition basis. And calculating current increment in each sampling period, judging a direction mark, updating a turning point sampling sequence number set and a turning point current value sequence when the direction is reversed, constructing a hysteresis history state and forming loop segment state input. Based on the loop segment state input, a segment-level loss mapping model is respectively established for the whole straight line segment and the whole circular arc segment, the whole straight line segment loss energy and the whole circular arc segment loss energy in each sampling period are recursively output and synthesized into single-pole total alternating current loss energy, and a coupling correction coefficient can be introduced when needed to obtain the output after coupling correction. The invention does not need to solve the whole field transient state of the electromagnetic field, and is suitable for on-line rapid evaluation and engineering application.

Inventors

CHEN XIN
WANG LEI
WANG CONG
LIU SHIWAN
LIU JIANHUA
WANG HUI
WANG QIULIANG

Assignees

中国科学院电工研究所

Dates

Publication Date: 20260508
Application Date: 20260304

Claims (11)

1. A dynamic AC loss analysis method for a high-temperature superconductive rotor magnet is characterized in that the method comprises the steps of: calculating a current increment in each sampling period by taking a discrete sampling value of an exciting current time sequence as a unique input quantity, and judging a direction mark, wherein the direction mark is used for representing the change direction of exciting current between adjacent sampling points; when the exciting current change direction is reversed, updating a turning point sampling sequence number set and a turning point current value sequence, wherein the turning point is a sampling point corresponding to the exciting current change direction when the exciting current change direction is reversed, constructing a hysteresis history state and forming loop segment state input; Based on the loop segment state input, establishing segment-level loss mapping models for the whole straight line segment and the whole circular arc segment respectively, wherein the segment-level loss mapping models are a mapping relation which takes the loop segment state input and the current increment as independent variables and takes the loss energy of the corresponding segment in the sampling period as the dependent variables; And recursively outputting the whole loss energy of the straight line segment and the whole loss energy of the circular arc segment in each sampling period, and synthesizing the whole loss energy into the single-pole total alternating current loss energy.
2. A dynamic AC loss analysis method for high temperature superconductive rotor magnet according to claim 1, wherein the coupling correction coefficient is introduced The corrected single-pole total alternating current loss energy is made to be 。
3. A dynamic AC loss analysis method of high temperature superconductive rotor magnet is characterized in that updating turning point set includes adding new turning point and removing turning point corresponding to covered inner loop based on extremum covering relation, when current value of new turning point and current interval formed by turning point of adjacent outer layer boundary completely cover current interval formed by removed turning point pair, judging that extremum covering relation exists, making turning point set always keep outer layer boundary turning information with decision function for current hysteresis loop, setting upper limit of turning point number, when turning point number exceeds upper limit, turning point with minimum sampling number is removed from small to large according to turning point sampling number, only last preset number of turning points are reserved to ensure memory and calculation quantity of hysteresis history state to keep limited and controllable.
4. The method for analyzing dynamic alternating current loss of high-temperature superconductive rotor magnet according to claim 1, wherein the loop segment state input comprises an upper boundary current value, a lower boundary current value, an effective current span, a segment advance amount and a segment type marking amount for distinguishing a main loop segment from a secondary loop segment, wherein the effective current span is an absolute value of a difference between the upper boundary current value and the lower boundary current value, the segment advance amount is a normalized advance amount of a current value between the upper boundary and the lower boundary along a current change direction, and the segment type marking amount is used for representing the main loop segment or the secondary loop segment.
5. The method of claim 4, wherein the loop segment type is determined based on comparing the extremum of the turning point current value sequence with the current value, and the main loop segment is determined when the upper or lower boundary current value of the loop segment is equal to the maximum or minimum value of the current turning point current value sequence, respectively, and the sub loop segment is determined otherwise.
6. The method for analyzing dynamic AC loss of high temperature superconductive rotor magnet according to claim 1, wherein the segment loss mapping model uses absolute values of segment equivalent dissipation coefficient and current increment The sampling period loss energy is calculated in the form of the product of the effective current span, the fragment advance amount and the fragment type mark amount, wherein the equivalent dissipation coefficient of the fragment level is jointly determined.
7. The method of analyzing dynamic AC loss of high temperature superconductive rotor magnet according to claim 6, wherein the equivalent dissipation factor of the segment is achieved by parameterizing an analytical function comprising a base line term, an amplitude term and a position influencing term, wherein the amplitude term describes the variation characteristic with effective current span in an exponential saturation form.
8. The method for analyzing dynamic alternating current loss of the high-temperature superconductive rotor magnet according to claim 1, wherein the model parameters are obtained through off-line calibration, the calibration process adopts a representative excitation current time sequence and corresponding reference loss data, the reference loss data comprise experimental measurement data and electromagnetic field numerical calculation data, and fitting solution is carried out by taking error minimization between model predicted loss energy and reference loss energy as a target.
9. The method of analyzing dynamic AC loss of a high temperature superconductive rotor magnet according to claim 1, wherein when the current increment is zero, the loss energy output in the sampling period is zero, and when the direction is determined reversely, the sampling period is regarded as the change direction which extends to the last non-zero current increment.
10. The method of claim 1, wherein the determination of the direction reversal is triggered based on a condition that the sign product of the current increment of the current sampling period and the last non-zero current increment, which is the last non-zero current increment traced back from the current sampling period, is less than zero.
11. A method for analyzing dynamic AC loss of high temperature superconductive rotor magnet according to any of claims 1-10, wherein the AC loss is AC electromagnetic dissipation loss generated by high temperature superconductive tape body in magnetic pole coil of rotor magnet.

Description

Dynamic alternating current loss analysis method for high-temperature superconductive rotor magnet Technical Field The invention belongs to the technical field of electromagnetic loss analysis of rotor magnets of high-temperature superconductive synchronous cameras, and particularly relates to a dynamic alternating current loss analysis method of a rotor magnet of a high-temperature superconductive. Background The high-temperature superconductive synchronous phase regulator obtains higher magnetic field and higher energy efficiency by adopting a high-temperature superconductive excitation winding on the rotor side, and a rotor magnet of the high-temperature superconductive synchronous phase regulator usually works in a low-temperature environment. In order to meet the requirements of reactive power regulation, running state switching, test working condition verification and the like, the rotor exciting current inevitably undergoes dynamic change processes such as strong excitation, rapid slope, step and the like in engineering operation. The rapid change of exciting current causes nonlinear evolution of current distribution and magnetic flux penetration state inside the superconducting tape, so that alternating current loss is generated, and the alternating current loss is deposited inside the rotor magnet in a thermal form, so that the alternating current loss is one of key electromagnetic factors affecting low-temperature stability and system reliability. For the high-temperature superconducting tape, the alternating current loss is closely related to the excitation process, and the hysteresis history effect is obvious. Even under the same current amplitude conditions, different current change paths, change rates, and preamble excitation histories result in different loss energy responses. In typical dynamic processes such as strong excitation slopes and steps, the hysteresis history effect is usually more remarkable, and if only the loss and the current amplitude are in static corresponding relation, the evaluation deviation of dynamic loss energy can be caused, so that the judgment of the load and the safety margin of the low-temperature system is affected. In the existing alternating current loss analysis method, one type of method relies on high-fidelity electromagnetic field numerical calculation and combines a material constitutive relation to obtain a loss result, finer spatial distribution can be given, but more complete geometric, material and boundary information is usually needed, the calculated amount is large, time stepping iteration is long, continuous updating is difficult to be carried out in a control system sampling period, meanwhile, the input amount is usually far more than information which is easily obtained in an engineering site, and quick evaluation is difficult to be realized by directly taking an excitation current sequence as a unique input. Another type of method introduces a large amount of experience coefficients or additional measurement quantity for reducing the calculation cost, and although the method can be used for estimating the total loss under specific conditions, the applicable boundary is not clear, and the hysteresis history effect in the strong excitation dynamic process is not enough to be characterized, so that the loss difference under different excitation histories is difficult to stably reproduce. Furthermore, there are significant differences in the electromagnetic environment of the rotor pole coil segments. Taking a racetrack coil as an example, the straight line section and the circular arc section of the racetrack coil are inconsistent in the aspects of external magnetic field distribution, field angle change, magnetic flux penetration path and the like, so that the alternating current loss presents a sectional non-uniformity characteristic inside the magnetic pole. In engineering, if only the total loss power or the total loss energy of the magnetic pole is given, the quantitative analysis of the structural characteristics is difficult to support, but the scheme capable of outputting the segmentation result in the existing method is generally established on the basis of complex electromagnetic field solving and fine geometric modeling, so that the burden of calculation force and input complexity is further increased, and the engineering requirement updated according to the sampling period is difficult to meet. Therefore, it is needed to provide a dynamic analysis method which has simple input, controllable calculation amount, can reflect hysteresis history effect and output alternating current loss energy of a magnetic pole straight line segment and a circular arc segment, realizes loss evaluation updated according to a sampling period under the condition of rapid change of strong excitation, and provides reliable basic data basis for subsequent related work. Disclosure of Invention The invention provides a dynamic alternating current loss analysis me