CN111913067A - Method, system, device and medium for measuring operation parameters of three-phase asymmetric converter - Google Patents
Method, system, device and medium for measuring operation parameters of three-phase asymmetric converter Download PDFInfo
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Abstract
The invention discloses a method, a system, a device and a medium for measuring operation parameters of a three-phase asymmetric converter, wherein the method comprises the steps of calculating zero-crossing offset of commutation voltage of each converter valve according to commutation voltage fundamental wave and third harmonic positive and negative sequence components, and correcting the trigger angle of each converter valve according to the relation between the zero-crossing offset and a trigger angle instruction value to obtain an actual trigger angle and a conduction delay angle; extracting direct current components and second harmonic components of direct current, and calculating according to an actual trigger angle, zero-crossing point offset, positive and negative sequence components of fundamental waves and third harmonics of alternating-current side commutation voltage and second harmonic components of direct-current side current to obtain the commutation angle of each converter valve; and determining a converter switching function model according to the actual trigger angle, the conduction delay angle and the phase change angle of each converter valve so as to obtain the operation parameters of the converter. The method considers the influence of harmonic waves on two sides of alternating current and direct current on the phase commutation process, improves the precision of a converter switching function model, and can be widely applied to the technical field of high-voltage direct-current transmission.
Description
Technical Field
The invention relates to the technical field of high-voltage direct-current transmission, in particular to a method, a system, a device and a medium for measuring operation parameters of a three-phase asymmetric converter.
Background
The high-voltage direct-current transmission system plays an important role in a modern power grid, and is a priority choice for underground cable power transmission, asynchronous interconnection of an alternating-current power grid and long-distance trans-regional power transmission. The quasi-steady-state model can accurately simulate the external characteristics of the converter under normal working conditions and is suitable for electromechanical transient simulation under the condition of larger step length, but the quasi-steady-state model neglects the harmonic characteristics of an alternating current side and a direct current side and cannot be suitable under asymmetric working conditions; the electromagnetic transient model can accurately represent the dynamic characteristics of each valve under a smaller step length by solving the differential equation set of each converter valve of the converter, but cannot meet the requirement on the solving efficiency due to the scale and the operation speed of a system.
The switch function method based on the modulation theory represents the switching-on and switching-off and phase-changing processes of the valve by Fourier series through analyzing the physical characteristics of the valve and the topological structure of a circuit, has higher precision under small step length, can be used for large step length simulation after high-order terms are ignored, and is widely applied to simulation of an alternating current-direct current hybrid system containing a converter. However, the conventional switching function method is established under a three-phase symmetric working condition, and the conduction time and the commutation parameters of each valve are consistent, so that the method cannot be applied to the output characteristic research of the converter under the asymmetric condition.
In fact, under a three-phase asymmetric working condition, due to different zero-crossing point offset conditions of each commutation voltage, the triggering conditions of each commutation valve are also inconsistent, and the conduction characteristic of each valve in the converter cannot be described by using a single triggering angle; meanwhile, due to the existence of non-characteristic harmonics on both sides of alternating current and direct current, the actual commutation time of each valve cannot be simply measured by a traditional commutation angle calculation method, and the change of the conduction characteristic and the influence of the harmonics on the commutation time need to be more accurately considered. However, some existing converter switching function models under three-phase asymmetric working conditions do not fully consider the influence of non-characteristic harmonics on the two sides of alternating current and direct current, so that the model precision is low, the operation parameters such as direct-current side voltage and alternating-current side current of the converter cannot be accurately measured, and the dynamic characteristics of the converter cannot be accurately and effectively analyzed.
Disclosure of Invention
The present invention aims to solve at least to some extent one of the technical problems existing in the prior art.
Therefore, an object of the embodiments of the present invention is to provide a method for determining operating parameters of a three-phase asymmetric converter, which considers the influence of an ac-side third harmonic and a dc-side second harmonic on a phase conversion process at the same time, and improves the accuracy of a switching function model of the converter, thereby improving the accuracy of determining the operating parameters of the converter and accurately describing the conduction characteristics of a converter valve under a three-phase asymmetric working condition.
Another object of an embodiment of the present invention is to provide a system for determining an operation parameter of a three-phase asymmetric converter.
In order to achieve the technical purpose, the technical scheme adopted by the embodiment of the invention comprises the following steps:
in a first aspect, an embodiment of the present invention provides a method for determining an operation parameter of a three-phase asymmetric converter, including the following steps:
determining the commutation voltage of each converter valve of the converter according to the three-phase voltage at the AC side of the converter, and further determining the synchronous phase of the phase-locked loop of the DC system according to the commutation voltage;
determining a fundamental wave positive and negative sequence component and a third harmonic positive and negative sequence component of the commutation voltage, and determining commutation voltage zero crossing point offset of each converter valve of the converter according to the fundamental wave positive and negative sequence component, the third harmonic positive and negative sequence component and the synchronous phase;
acquiring a trigger angle instruction value output by a direct current system, and determining an actual trigger angle and a conduction delay angle of each converter valve of the converter according to the trigger angle instruction value and the zero-crossing offset of the commutation voltage;
acquiring a direct current component and a second harmonic component of direct current, and obtaining a conversion angle of each converter valve of the converter according to the fundamental wave positive and negative sequence component, the third harmonic positive and negative sequence component, the direct current component and the second harmonic component;
and determining a converter switching function model according to the actual trigger angle, the conduction delay angle and the phase change angle, and further obtaining converter operating parameters according to the switching function model.
Further, in an embodiment of the present invention, the step of determining a commutation voltage of each converter valve of the converter according to a three-phase voltage at an ac side of the converter, and further determining a synchronous phase of a phase-locked loop of a dc system according to the commutation voltage specifically includes:
the method comprises the steps of obtaining three-phase voltage on the alternating current side of the converter, and obtaining the conversion voltage of each converter valve of the converter after carrying out linear conversion on the three-phase voltage;
performing Clark transformation on the commutation voltage to obtain a first component and a second component of the commutation voltage;
and determining the synchronous phase of the direct current system phase-locked loop according to the first component and the second component.
Further, in an embodiment of the present invention, the step of determining a fundamental positive-negative sequence component and a third harmonic positive-negative sequence component of the commutation voltage, and determining a zero-crossing offset of the commutation voltage of each valve of the converter according to the fundamental positive-negative sequence component, the third harmonic positive-negative sequence component, and the synchronous phase specifically includes:
extracting fundamental wave components and third harmonic components of the commutation voltage, carrying out symmetrical component transformation on the fundamental wave components to obtain fundamental wave positive and negative sequence components of the commutation voltage, and carrying out symmetrical component transformation on the third harmonic components to obtain third harmonic positive and negative sequence components of the commutation voltage;
determining the actual zero crossing point of commutation voltage according to the fundamental wave positive and negative sequence component, the third harmonic positive and negative sequence component and the synchronous phase;
and determining the steady-state zero crossing point of the commutation voltage of each converter valve of the converter under the three-phase balance working condition, and obtaining the zero crossing offset of the commutation voltage of each converter valve of the converter according to the actual zero crossing point of the commutation voltage and the steady-state zero crossing point of the commutation voltage.
Further, in an embodiment of the present invention, the step of determining an actual firing angle and a conduction delay angle of each converter valve of the converter according to the firing angle command value and the zero-crossing shift amount of the converter voltage specifically includes:
if the commutation voltage zero-crossing offset is greater than the trigger angle instruction value, determining that the conduction delay angle is the difference value between the commutation voltage zero-crossing offset and the trigger angle instruction value, and the actual trigger angle is 0; and if the zero-crossing offset of the commutation voltage is less than or equal to the trigger angle instruction value, determining that the actual trigger angle is the difference value between the trigger angle instruction value and the zero-crossing offset of the commutation voltage, and the conduction delay angle is 0.
Further, in an embodiment of the present invention, the step of determining a switching function model of the converter according to the actual firing angle, the conduction delay angle, and the commutation angle, and further obtaining an operating parameter of the converter according to the switching function model specifically includes:
obtaining a converter switching function component according to the actual trigger angle, the conduction delay angle and the phase change angle;
carrying out Fourier expansion, phase shift processing and superposition processing on the converter switching function component to obtain a converter switching function model;
determining converter operation parameters according to the converter switching function model;
wherein the converter switching function model includes a converter voltage switching function and a converter current switching function.
Further, in one embodiment of the invention, the converter switching function component comprises a base component, a correction component and a commutation component.
Further, in an embodiment of the present invention, the converter operation parameters include a converter dc side harmonic voltage and a converter injection harmonic current into an ac system, and the step of determining the converter operation parameters according to the converter switching function model specifically includes:
determining the harmonic voltage of the direct current side of the converter according to the voltage switching function and the three-phase voltage;
and determining the harmonic current injected into the alternating current system by the converter according to the current switching function and the direct current.
In a second aspect, an embodiment of the present invention provides an operation parameter measurement system for a three-phase asymmetric converter, including:
the synchronous phase determining module is used for determining the commutation voltage of each converter valve of the converter according to the three-phase voltage at the AC side of the converter, and further determining the synchronous phase of the direct-current system phase-locked loop according to the commutation voltage;
the zero crossing point offset determining module is used for determining a fundamental wave positive and negative sequence component and a third harmonic positive and negative sequence component of the commutation voltage and determining the commutation voltage zero crossing point offset of each converter valve of the converter according to the fundamental wave positive and negative sequence component, the third harmonic positive and negative sequence component and the synchronous phase;
the actual trigger angle and conduction delay angle determining module is used for acquiring a trigger angle instruction value output by a direct current system and determining an actual trigger angle and a conduction delay angle of each converter valve of the converter according to the trigger angle instruction value and the zero-crossing offset of the commutation voltage;
the converter angle determining module is used for acquiring a direct current component and a second harmonic component of direct current, and obtaining the converter angle of each converter valve of the converter according to the fundamental wave positive and negative sequence component, the third harmonic positive and negative sequence component, the direct current component and the second harmonic component;
and the operation parameter calculation module is used for determining a converter switching function model according to the actual trigger angle, the conduction delay angle and the phase change angle and further obtaining the converter operation parameters according to the switching function model.
In a third aspect, an embodiment of the present invention provides an apparatus for determining an operation parameter of a three-phase asymmetric converter, including:
at least one processor;
at least one memory for storing at least one program;
when executed by the at least one processor, the at least one program causes the at least one processor to implement a method of determining operating parameters of a three-phase asymmetric converter as described above.
In a fourth aspect, the present invention further provides a computer-readable storage medium, in which a program executable by a processor is stored, and when the program is executed by the processor, the program is configured to perform the above-mentioned method for determining the operation parameters of the three-phase asymmetric converter.
Advantages and benefits of the present invention will be set forth in part in the description which follows and, in part, will be obvious from the description, or may be learned by practice of the invention:
the method comprises the steps of obtaining a commutation voltage, obtaining positive and negative sequence components of fundamental waves and third harmonics of the commutation voltage through conversion, calculating zero crossing point offset of the commutation voltage of each converter valve according to the positive and negative sequence components of the fundamental waves and the third harmonics of the commutation voltage, and correcting the firing angle of each converter valve according to the relation between the zero crossing point offset and a firing angle instruction value to obtain an actual firing angle and a conduction delay angle; extracting direct current, obtaining direct current components and second harmonic components through conversion, and calculating according to an actual trigger angle, zero-crossing point offset, positive and negative sequence components of fundamental waves and third harmonics of alternating-current side commutation voltage and second harmonic components of direct-current side current to obtain commutation angles of all the converter valves; and determining a converter switching function model according to the actual trigger angle, the conduction delay angle and the phase change angle of each converter valve so as to obtain the operation parameters of the converter. According to the embodiment of the invention, the influence of zero crossing point offset of the converter voltage on the conduction process of the converter valve and the influence of the third harmonic wave on the alternating current side and the second harmonic wave on the direct current side on the phase conversion process are considered, and the precision of a switch function model of the converter is improved, so that the accuracy of measuring the operation parameters of the converter is improved, and the conduction characteristic of the converter valve under the three-phase asymmetric working condition can be accurately described.
Drawings
In order to more clearly illustrate the technical solution in the embodiment of the present invention, the following description is made on the drawings required to be used in the embodiment of the present invention, and it should be understood that the drawings in the following description are only for convenience and clarity of describing some embodiments in the technical solution of the present invention, and it is obvious for those skilled in the art that other drawings can be obtained according to these drawings without creative efforts.
Fig. 1 is a flowchart illustrating steps of a method for determining operating parameters of a three-phase asymmetric converter according to an embodiment of the present invention;
fig. 2 is a block diagram of an operation parameter measurement system of a three-phase asymmetric converter according to an embodiment of the present invention;
fig. 3 is a block diagram of an operation parameter measuring device for a three-phase asymmetric converter according to an embodiment of the present invention;
FIG. 4(a) is a schematic diagram of a first case of a relationship between zero-crossing offset of commutation voltage and firing angle under an asymmetric working condition according to an embodiment of the present invention;
FIG. 4(b) is a diagram illustrating a second case of a relationship between zero-crossing offset of commutation voltage and firing angle under an asymmetric working condition according to an embodiment of the present invention;
FIG. 4(c) is a schematic diagram of a third case of a relationship between zero-crossing offset of commutation voltage and firing angle under an asymmetric working condition according to an embodiment of the present invention;
fig. 5 is a comparison graph of a sine voltage waveform after zero-crossing offset correction and an actual commutation voltage waveform according to an embodiment of the present invention;
fig. 6(a) is a waveform diagram of the fundamental component of the switching function of the converter provided by the embodiment of the present invention;
fig. 6(b) is a waveform diagram of a voltage commutation component of a converter switching function provided by an embodiment of the present invention;
fig. 6(c) is a waveform diagram of a current commutation component of a converter switching function provided by an embodiment of the present invention;
fig. 6(d) is a waveform diagram of a correction component of a switching function of an inverter according to an embodiment of the present invention;
fig. 7(a) is a comparison graph of a calculated rectified side dc voltage value and a simulated PSCAD electromagnetic transient value according to an embodiment of the present invention;
fig. 7(b) is a comparison graph of the calculated dc voltage value on the inverting side and the simulated electromagnetic transient value of PSCAD according to the embodiment of the present invention;
fig. 7(c) is a comparison graph of a calculated rectified side ac current value and a simulated PSCAD electromagnetic transient value according to an embodiment of the present invention;
fig. 7(d) is a comparison graph of the calculated inverter side ac current value and the simulated PSCAD electromagnetic transient value according to the embodiment of the present invention.
Detailed Description
Reference will now be made in detail to embodiments of the present invention, examples of which are illustrated in the accompanying drawings, wherein like or similar reference numerals refer to the same or similar elements or elements having the same or similar function throughout. The embodiments described below with reference to the accompanying drawings are illustrative only for the purpose of explaining the present invention, and are not to be construed as limiting the present invention. The step numbers in the following embodiments are provided only for convenience of illustration, the order between the steps is not limited at all, and the execution order of each step in the embodiments can be adapted according to the understanding of those skilled in the art.
In the description of the present invention, the meaning of a plurality is two or more, if there is a description to the first and the second for the purpose of distinguishing technical features, it is not understood as indicating or implying relative importance or implicitly indicating the number of indicated technical features or implicitly indicating the precedence of the indicated technical features. Furthermore, unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art.
Hereinafter, an operation parameter determination method and system for a three-phase asymmetric converter according to an embodiment of the present invention will be described in detail with reference to the accompanying drawings, and first, an operation parameter determination method for a three-phase asymmetric converter according to an embodiment of the present invention will be described with reference to the accompanying drawings.
Referring to fig. 1, an embodiment of the present invention provides a method for determining an operation parameter of a three-phase asymmetric converter, including the following steps:
s101, determining the commutation voltage of each converter valve of the converter according to the three-phase voltage at the AC side of the converter, and further determining the synchronous phase of the direct-current system phase-locked loop according to the commutation voltage.
Specifically, three-phase voltage vectors on a converter bus are obtained, then the converter voltage of each converter valve of the converter is calculated, and then the synchronous phase of the direct-current system phase-locked loop is calculated. Step S101 specifically includes the following steps:
s1011, obtaining three-phase voltage at the AC side of the converter, and performing linear transformation on the three-phase voltage to obtain the conversion voltage of each converter valve of the converter;
specifically, three-phase voltage on a converter bus is obtained
And linearly converting the three-phase voltage to obtain a phase-change voltage
The following were used:
wherein, Uca、Uab、UbcRespectively the fundamental amplitude of the commutation voltage,
the fundamental phases of the commutation voltages are respectively.
S1012, performing Clark conversion on the phase-change voltage to obtain a first component and a second component of the phase-change voltage.
Specifically, Clark conversion is carried out on the phase-change voltage to obtain a first component of the phase-change voltage, namely an alpha component
And a second component, beta component
Wherein, UαFundamental amplitude, U, of the alpha componentβIs the fundamental amplitude of the beta component,
is the phase of the fundamental wave of the alpha component,
is the fundamental phase of the beta component.
And S1013, determining the synchronous phase of the direct current system phase-locked loop according to the first component and the second component.
Specifically, the synchronous phase of the phase-locked loop of the dc system can be calculated by the following formula:
where θ represents the synchronous phase of the dc system phase locked loop.
S102, determining a fundamental wave positive-negative sequence component and a third harmonic positive-negative sequence component of the commutation voltage, and determining commutation voltage zero crossing point offset of each commutation valve of the converter according to the fundamental wave positive-negative sequence component, the third harmonic positive-negative sequence component and the synchronous phase.
Specifically, according to the obtained commutation voltage, a fundamental component and a third harmonic component of the commutation voltage are extracted, symmetrical component conversion is carried out to obtain a fundamental positive-negative sequence component and a third harmonic positive-negative sequence component, and then the commutation voltage zero-crossing point offset of the converter under the three-phase asymmetric working condition can be obtained by combining the steady-state zero-crossing point of the commutation voltage under the three-phase balanced working condition. Step S102 specifically includes the following steps:
s1021, extracting a fundamental component and a third harmonic component of the commutation voltage, performing symmetrical component transformation on the fundamental component to obtain a fundamental positive-negative sequence component of the commutation voltage, and performing symmetrical component transformation on the third harmonic component to obtain a third harmonic positive-negative sequence component of the commutation voltage;
s1022, determining the actual zero crossing point of the commutation voltage according to the positive and negative sequence components of the fundamental wave, the positive and negative sequence components of the third harmonic and the synchronous phase;
and S1023, determining the steady-state zero crossing point of the commutation voltage of each converter valve of the converter under the three-phase balance working condition, and obtaining the zero crossing offset of the commutation voltage of each converter valve of the converter according to the actual zero crossing point of the commutation voltage and the steady-state zero crossing point of the commutation voltage.
Specifically, the converter comprises a Y0/Y (star connection) connected converter and a Y0/delta (delta connection) connected converter, the embodiment of the invention simultaneously describes two connected converters, and the Y0/Y is connected with the zero-crossing offset delta of the commutation voltage of each bridge arm converter valve of the converteryi(i is 1,2 and 3) and Y0/delta is connected with zero-crossing offset delta of commutation voltage of each bridge arm converter valve of the converterdiThe specific calculation procedure for (i ═ 1,2,3) is as follows:
fourier decomposition is carried out on the phase-change voltage, fundamental voltage components and third harmonic voltage components are extracted, and symmetrical component transformation is respectively carried out to obtain positive and negative sequence components of the fundamental voltage
And
and third harmonic voltage positive and negative sequence components
And
wherein, U1 +、U1 -、U3 +、U3 -Respectively showing the amplitudes of the positive and negative sequence components of the fundamental wave and the positive and negative sequence components of the third harmonic wave,
respectively representing the angle of lagging synchronous phase, theta represents the synchronous phase of the phase-locked loop output;
the steady-state zero crossing point of the converter phase voltage of each bridge arm of the Y0/Y connected converter under the three-phase balance working condition is phiyi(i is 1,2 and 3), Y0/delta is connected with each bridge arm converter valve of the converter, the steady-state zero-crossing point of the converter voltage is phidi(i-1, 2 and 3), under the three-phase unbalanced condition, the actual zero-crossing point of the converter phase voltage of each bridge arm converter valve of the Y0/Y-connected converter is phi'yi(i-1, 2 and 3), Y0/delta is connected with each bridge arm converter valve phase change voltage of the converter, and the actual zero-crossing point is phi'di(i ═ 1,2,3), the inverter zero crossing offset can be expressed as:
wherein phiy1＝0，
Substituting the zero-crossing point offset of the converter into an expression of the commutation voltage to obtain a set of trigonometric equations about the zero-crossing point offset:
and (3) performing Taylor expansion on the equation set near the zero point to obtain a set of quadratic equations about zero-crossing point offset:
wherein:
further, the zero-crossing point offset of the two types of converters can be solved as follows:
s103, acquiring a trigger angle instruction value output by the direct current system, and determining the actual trigger angle and the conduction delay angle of each converter valve of the converter according to the trigger angle instruction value and the zero-crossing offset of the commutation voltage.
Specifically, a firing angle command value α is output according to a direct current systemoAnd the zero-crossing point offset amount Δ obtained in step S102yiAnd ΔdiObtaining the actual trigger angle alpha of the converter valve of each bridge arm of the Y0/Y-connection converteryiAnd on delay angle Δ θyiAnd Y0/delta actual trigger angle alpha of converter valve of each bridge arm of converterdiAnd on delay angle Δ θdi. Step S103 is specifically as follows:
if the zero-crossing offset of the commutation voltage is greater than the trigger angle instruction value, determining that the conduction delay angle is the difference value between the zero-crossing offset of the commutation voltage and the trigger angle instruction value, and the actual trigger angle is 0; and if the zero crossing offset of the commutation voltage is less than or equal to the trigger angle instruction value, determining that the actual trigger angle is the difference value between the trigger angle instruction value and the zero crossing offset of the commutation voltage, and the conduction delay angle is 0.
In the embodiment of the invention, the zero-crossing offset delta of the commutation voltage of the Y0/Y-connected converter is comparedyiAnd the firing angle command value alphaoIf Δyi<αoThe actual zero crossing point of the commutation voltage is advanced from the arrival time of the trigger pulse, and the actual trigger angle alpha is shownyi＝αo-Δyi(ii) a If Δyi>αoExplaining that the zero crossing point of the commutation voltage lags behind the arrival time of the trigger pulse, and the commutation voltage does not change positive yet, the conduction time of the valve is delayed by delta thetayi＝Δyi-αo. The Y0/delta connection converter is corrected by the same method to obtain the actual trigger angle alphadiAnd delayed conduction angle delta thetadi。
FIGS. 4(a) to 4(c) show three cases of zero-crossing offset of commutation voltage and firing angle under asymmetric conditions, wherein α1Representing the actual firing angle (alpha)yiOr alphadi)，Δ1Representing the zero-crossing offset (Delta) of the commutation voltageyiOr Δdi) (ii) a FIG. 4(a) shows α when the commutation voltage zero crossing leads the synchronous reference voltage zero crossing1、Δ1And alphaoThe relationship between; FIG. 4(b) shows α when the zero-crossing of the commutation voltage lags the zero-crossing of the synchronous reference voltage but leads the firing angle1、Δ1And alphaoThe relationship between; FIG. 4(c) shows α when the zero-crossing point of the commutation voltage lags the firing angle1、Δ1And alphaoThe relationship between them.
Y0/actual firing angle alpha of each converter valve of Y-connection converteryiAnd on delay angle Δ θyiCan be expressed as follows：
Similarly, the actual firing angle α for a Y0/Δ converterdiAnd on delay angle Δ θdiIn other words, only the parameter Δ in the above two equations is usedyiSubstitution by ΔdiAnd (4) finishing.
And S104, acquiring a direct current component and a second harmonic component of the direct current, and obtaining the commutation angle of each converter valve of the converter according to the fundamental wave positive-negative sequence component, the third harmonic positive-negative sequence component, the direct current component and the second harmonic component.
Optionally, the conversion angle μ of each converter valve of the Y0/Y-connected converter is calculated through the fundamental positive-negative sequence component and the third harmonic positive-negative sequence component of the phase-converted voltage of the Y0/Y-connected converter, the direct-current component and the second harmonic component of the direct currentyiThe process of (2) is as follows:
according to the amplitude and the phase of the harmonic component of the alternating-current side commutation voltage of the Y0/Y-connected converter and the harmonic component and the phase of the direct-current side direct current, calculating intermediate quantity as follows:
wherein, XBFor commutation reactance, Id0And Id2The magnitudes of the dc component and the second harmonic component of the dc current respectively,
the angle of the phase lag synchronous phase of the direct current second harmonic is the angle of the phase lag synchronous phase;
calculating the conversion angle mu of each converter valve of the Y0/Y-connected converter according to the intermediate quantityyi：
Wherein the content of the first and second substances,
and
after the k +1 th iteration and after the k +1 th iteration respectivelyyiThe value of (a).
Similarly, for the phase change angle mu of the Y0/delta connection converterdiOnly the parameter alpha in the above formula is neededyi、Δyi、φyiCorresponding is replaced by alphadi、Δdi、φdiThe iterative calculation may be performed in the same manner.
And S105, determining a converter switching function model according to the actual trigger angle, the conduction delay angle and the phase change angle, and further obtaining converter operating parameters according to the converter switching function model.
Specifically, a converter switching function component is calculated according to the actual trigger angle and the conduction delay angle of each converter valve obtained in step S103 and the converter angle of each converter valve obtained in step S104, a converter switching function model is determined, and a converter operating parameter is calculated according to the converter switching function model. Step S105 specifically includes the following steps:
s1051, obtaining a converter switching function component according to an actual trigger angle, a conduction delay angle and a phase change angle;
s1052, carrying out Fourier expansion, phase shift processing and superposition processing on the switching function component of the converter to obtain a switching function model of the converter;
and S1053, determining the operation parameters of the converter according to the switching function model of the converter.
The converter switching function model comprises a converter voltage switching function and a converter current switching function.
Further as an alternative embodiment, the converter switching function component comprises a base component, a correction component and a commutation component.
In the embodiment of the invention, the process of obtaining the switching function model of the converter by calculating the basic component, the correction component, the voltage commutation component and the current commutation component of the switching function of the Y0/Y-connected converter, and performing Fourier expansion, phase shift processing and superposition processing on the basic component, the correction component, the voltage commutation component and the current commutation component is as follows:
according to the obtained Y0/Y connection converter actual trigger angle alphayiOn delay angle Δ θyiAnd a phase change angle muyiCalculating a fundamental component SbasYVoltage commutation component SμuYCurrent commutation component SμiYAnd correcting the component ScorYAnd Fourier expansion is carried out by taking the symmetry axis of the basic component as a reference as follows:
wherein:
the above components are phase-shifted to obtain a fundamental component S which can be interfaced with a DC system having a synchronous phase outputted from a phase-locked loop as a reference phasebasxYVoltage commutation component SμuxYCurrent commutation component SμixYAnd correcting the component ScorxY：
Wherein x ═ a, b, c represent three phases, corresponding to k ═ 0, 1,2, respectively;
then Y0/Y connects to the converter voltage switching function SuxYAnd current switching function SixYThe phase-shifted components can be superposed to obtain:
similarly, the same method can be adopted for the Y0/delta converter, and only the synchronous reference phase in the Fourier expansion is delayed by pi/6, wherein alpha isyi、Δθyi、μyiCorresponding is replaced by alphadi、Δθdi、μdiThe corresponding basic component S can be obtainedbasDVoltage commutation component SμuDCurrent commutation component SμiDAnd correcting the component ScorDThen, the phase shift processing is carried out to obtain S of the interface with the DC systembasxD、SμuxD、SμixDAnd ScorxDFinally, the voltage switching function S of the Y0/delta connection converter is obtained by superpositionuxDAnd current switching function SixD。
Optionally, since there is no zero sequence component path on the valve side of the Y0/Y converter and the Y0/Δ converter, and the positive and negative sequence components on both sides of the Y0/Δ converter generate phase shift, it is necessary to convert the two types of converter valve-side current switch functions into the grid-side current switch function S'ixYAnd S'ixD：
Where m is the transformation ratio of the transformation flow, T is the symmetric component transformation matrix, and a is ej2π/3Is a twiddle factor.
Further as an optional implementation manner, the converter operation parameters include a converter dc-side harmonic voltage and a harmonic current injected into the ac system by the converter, and step S1053 specifically includes:
s10531, determining the harmonic voltage of the direct current side of the converter according to the voltage switching function and the three-phase voltage;
and S10532, determining harmonic current injected into the alternating current system by the converter according to the current switching function and the direct current.
Specifically, the calculated voltage switching function is multiplied by the three-phase voltage at the alternating current side of the converter to obtain harmonic voltages at two ends of the direct current side of the twelve-pulse converter, and the harmonic current injected into the alternating current system by the twelve-pulse converter can be obtained by multiplying the current switching function by the direct current and performing filtering processing.
In the embodiment of the invention, the voltage switching function S is based on the Y0/Y converteruxYAnd current switching function Si'xYAnd Y0/delta connection converter voltage switching function SuxDAnd current switching function S'ixDThe voltage U on two sides of the harmonic voltage source equivalent to the DC side of the 12-pulse converter can be writtendcsRelation with three-phase voltage at valve side, and harmonic current I injected into AC system by harmonic current source equivalent to 12-pulse current converter at AC sidesxRelationship to direct current:
wherein, UYyAnd UYDIs converter valve side three-phase voltage, S'ixYAnd S'ixDAs a function of the current switching equivalent to the network side, IdIs a direct current.
Optionally, the voltage U of a harmonic voltage source equivalent to the inverterdcsAnd the DC side measures the voltage UdcThere is a voltage drop between them, which is the equivalent internal resistance Z of the converter on the DC sidesCaused by, thereby obtaining UdcsAnd UdcThe relationship of (1) is:
Udc(p)＝Udcs(p)-Id(p)Zs(p)
wherein p is the harmonic frequency of the direct current side;
the equivalent internal resistance of the twelve-pulse converter can be calculated by the following formula:
wherein, XBIs the leakage reactance of the converter flow.
Compared with the prior art, the embodiment of the invention has the following advantages and effects:
(1) most of the existing high-voltage direct-current projects adopt an equal-interval triggering mode, and under a normal working condition, because the phase difference of the phase-change voltage of each converter valve is consistent, and the output phase of a phase-locked loop is equal to the phase of the phase-change voltage, the actual triggering angle of each valve can be ensured to be equal to an instruction value; under the asymmetric working condition, the zero crossing point of the commutation voltage of each valve generates offset, and the phase difference of the commutation voltages is not equal any more due to different offset, so that the triggering angle of each valve is not equal to the command value and is asymmetric; the embodiment of the invention deduces the zero crossing point offset by extracting the positive and negative sequence components of the fundamental frequency and the third harmonic of the alternating-current side phase-changing voltage so as to determine the actual trigger angle and the conduction delay angle of each valve.
(2) The commutation process of the converter is essentially that commutation voltage provided by an alternating current system and direct current at a direct current side participate together, so harmonic waves at two sides of alternating current and direct current can obviously influence the commutation duration of the valve, and under the normal condition, the amplitude of the commutation voltage on each valve is equal and the direct current is constant in the conduction process, so the commutation angles are also equal; in the embodiment of the invention, the harmonic waves at two sides of the converter can be considered to analyze the phase change process more accurately.
(3) Under the asymmetric working condition, the inconsistency of the conduction and the commutation characteristics of the converter valve needs to be considered more accurately, the embodiment of the invention adopts the basic component, the voltage commutation component, the current commutation component and the correction component to simulate the conduction and the commutation parameters of each valve, and the dynamic characteristics of the converter can be analyzed more accurately.
The effect of the embodiment of the present invention is further explained by comparing with the electromagnetic transient simulation result.
Taking the single-phase asymmetric fault of the converter bus as an example, the invention is applied to a CIGRE high-voltage direct current standard test model and compared with a PSCAD electromagnetic transient simulation result. Setting single-phase earth fault with transition resistance impedance of 25 omega on rectification and inversion sides, and fixing trigger angle to eliminate fault after reaching steady stateThe influence of the control system on the model, Table 1 is the calculated parameters of the commutation and inversion sides in steady state under fault, where Un sAnd IdnIn order to be the amplitude value,
and
the angle of the reference phase is synchronized for lag.
TABLE 1
According to the step S102, the zero-crossing offset of the commutation voltages of the two converters is calculated, as shown in fig. 5, a comparison graph of a result obtained by substituting the zero-crossing offset into the sinusoidal voltage signal for correction and a commutation voltage waveform on the actual commutation bus obtained through simulation test in the embodiment of the present invention is obtained, and it can be seen from fig. 5 that the error between the zero-crossing point of the sinusoidal signal and the zero-crossing point of the actual commutation voltage is very small, so that the zero-crossing offset can be considered to be calculated accurately.
According to the step S103, the zero crossing point offset of the commutation voltage obtained based on the step S102 is compared with the firing angle instruction value, the actual firing angle and the delay conduction angle of the valve can be obtained after correction, and the actual firing angle obtained by calculation is compared with the actual firing angle obtained by simulation test in the table 2, wherein alpha isynFor Y0/Y connection to the actual firing angle, alpha, of each converter valve of the converterdnThe actual firing angle of each converter valve of the converter is connected with Y0/delta. As can be seen from table 2, in the case of a constant firing angle command value, the actual firing angles of the valves are no longer equal, and the system is actually fired at unequal intervals, which causes generation of non-characteristic harmonics.
TABLE 2
According to step S104, pass eachCalculating the electric quantity calculating parameters, calculating the actual commutation angle of each valve and the zero-crossing point offset, comparing the calculated values with the simulation measured values, and comparing the calculated values with the simulation measured values in the table 3, wherein mu isynThe conversion angle mu of each converter valve of the Y0/Y connected converterdnThe conversion angle of each converter valve of the converter is connected with Y0/delta. It can be seen from table 3 that the commutation angle obtained taking into account the ac-dc side harmonics can fit the simulated value relatively well.
TABLE 3
According to step S105, the basic component, the voltage commutation component, the current commutation component, and the correction component of each bridge arm converter valve are calculated from the actual firing angle, the phase conversion angle, and the delay conduction angle of each valve.
Fig. 6(a) to 6(d) are waveform diagrams of a basic component, a voltage commutation component, a current commutation component and a correction component of an inverter switching function according to an embodiment of the present invention, where fig. 6(a) is a waveform diagram of the basic component, fig. 6(b) is a waveform diagram of the voltage commutation component, fig. 6(c) is a waveform diagram of the current commutation component, and fig. 6(d) is a waveform diagram of the correction component.
And then phase-shifting and superposing are carried out to obtain a voltage switching function and a current switching function of the converter, and further to calculate direct current voltage at two ends of the twelve-pulse converter and current injected into an alternating current system.
Fig. 7(a) to 7(d) are comparison diagrams of the dc voltage and the ac current calculated by the inverter switching function and the dc voltage and the ac current obtained by the PSCAD electromagnetic transient simulation according to the embodiment of the present invention, where fig. 7(a) is a comparison diagram of a calculated value of the rectified side dc voltage and an electromagnetic transient simulation value according to the embodiment of the present invention, fig. 7(b) is a comparison diagram of a calculated value of the inverted side dc voltage and an electromagnetic transient simulation value according to the embodiment of the present invention, fig. 7(c) is a comparison diagram of a calculated value of the rectified side ac current and an electromagnetic transient simulation value according to the embodiment of the present invention, and fig. 7(d) is a comparison diagram of a calculated value of the inverted side ac current and an electromagnetic transient simulation value according to the embodiment of the present invention. It can be seen from fig. 7(a) to 7(d) that the current waveform outputted by the switching function is better matched with the simulated value in terms of amplitude, trend and pulse number, while the outputted dc voltage waveform can be matched with the simulated value in terms of trend and pulse number, and there is a certain difference in amplitude due to the equivalent internal resistance voltage drop from the simulated value.
In order to further verify the accuracy of the algorithm, the harmonic amplitude of the voltage output by the switching function is extracted, the voltage drop caused by the equivalent internal resistance on the direct current side is considered, the calculated voltage is compared with the simulation value, and the result is shown in table 4, and it can be seen that the calculated amplitude of each harmonic voltage can be basically consistent with the simulation result.
TABLE 4
Similarly, the current value outputted from the twelve-pulse inverter to the grid side is also subjected to the processing of extracting each harmonic, and a comparison with the simulated value is shown in table 5, and it can be seen that the calculated amplitude of each harmonic can be better matched with the simulated value.
TABLE 5
Referring to fig. 2, an embodiment of the present invention provides a three-phase asymmetric converter operation parameter measurement system, including:
the synchronous phase determining module is used for determining the commutation voltage of each converter valve of the converter according to the three-phase voltage at the AC side of the converter, and further determining the synchronous phase of the direct-current system phase-locked loop according to the commutation voltage;
the zero crossing point offset determining module is used for determining a fundamental wave positive and negative sequence component and a third harmonic positive and negative sequence component of the commutation voltage and determining the commutation voltage zero crossing point offset of each commutation valve of the converter according to the fundamental wave positive and negative sequence component, the third harmonic positive and negative sequence component and the synchronous phase;
the actual trigger angle and conduction delay angle determining module is used for acquiring a trigger angle instruction value output by the direct current system and determining the actual trigger angle and the conduction delay angle of each converter valve of the converter according to the trigger angle instruction value and the zero-crossing offset of the commutation voltage;
the converter phase angle determining module is used for acquiring a direct current component and a second harmonic component of the direct current and obtaining the converter phase angle of each converter valve of the converter according to the fundamental wave positive and negative sequence component, the third harmonic positive and negative sequence component, the direct current component and the second harmonic component;
and the operation parameter calculation module is used for determining a converter switching function model according to the actual trigger angle, the conduction delay angle and the phase change angle, and further obtaining the converter operation parameters according to the switching function model.
The contents in the above method embodiments are all applicable to the present system embodiment, the functions specifically implemented by the present system embodiment are the same as those in the above method embodiment, and the beneficial effects achieved by the present system embodiment are also the same as those achieved by the above method embodiment.
Referring to fig. 3, an embodiment of the present invention provides an apparatus for determining an operation parameter of a three-phase asymmetric converter, including:
at least one processor;
at least one memory for storing at least one program;
when the at least one program is executed by the at least one processor, the at least one processor may implement the method for determining the operation parameters of the three-phase asymmetric converter.
The contents in the above method embodiments are all applicable to the present apparatus embodiment, the functions specifically implemented by the present apparatus embodiment are the same as those in the above method embodiments, and the advantageous effects achieved by the present apparatus embodiment are also the same as those achieved by the above method embodiments.
The embodiment of the invention also provides a computer-readable storage medium, in which a program executable by a processor is stored, and the program executable by the processor is used for executing the method for determining the operation parameters of the three-phase asymmetric converter when the program is executed by the processor.
The computer-readable storage medium provided by the embodiment of the invention can execute the method for determining the operation parameters of the three-phase asymmetric converter provided by the embodiment of the method, can execute any combination of the implementation steps of the embodiment of the method, and has corresponding functions and beneficial effects of the method.
In alternative embodiments, the functions/acts noted in the block diagrams may occur out of the order noted in the operational illustrations. For example, two blocks shown in succession may, in fact, be executed substantially concurrently, or the blocks may sometimes be executed in the reverse order, depending upon the functionality/acts involved. Furthermore, the embodiments presented and described in the flow charts of the present invention are provided by way of example in order to provide a more thorough understanding of the technology. The disclosed methods are not limited to the operations and logic flows presented herein. Alternative embodiments are contemplated in which the order of various operations is changed and in which sub-operations described as part of larger operations are performed independently.
Furthermore, although the present invention is described in the context of functional modules, it should be understood that, unless otherwise stated to the contrary, one or more of the above-described functions and/or features may be integrated in a single physical device and/or software module, or one or more of the functions and/or features may be implemented in a separate physical device or software module. It will also be appreciated that a detailed discussion of the actual implementation of each module is not necessary for an understanding of the present invention. Rather, the actual implementation of the various functional modules in the apparatus disclosed herein will be understood within the ordinary skill of an engineer, given the nature, function, and internal relationship of the modules. Accordingly, those skilled in the art can, using ordinary skill, practice the invention as set forth in the claims without undue experimentation. It is also to be understood that the specific concepts disclosed are merely illustrative of and not intended to limit the scope of the invention, which is defined by the appended claims and their full scope of equivalents.
The above functions, if implemented in the form of software functional units and sold or used as a separate product, may be stored in a computer-readable storage medium. Based on such understanding, the technical solution of the present invention may be embodied in the form of a software product, which is stored in a storage medium and includes instructions for causing a computer device (which may be a personal computer, a server, or a network device) to execute all or part of the steps of the above method according to the embodiments of the present invention. And the aforementioned storage medium includes: a U-disk, a removable hard disk, a Read-Only Memory (ROM), a Random Access Memory (RAM), a magnetic disk or an optical disk, and other various media capable of storing program codes.
The logic and/or steps represented in the flowcharts or otherwise described herein, e.g., an ordered listing of executable instructions that can be considered to implement logical functions, can be embodied in any computer-readable medium for use by or in connection with an instruction execution system, apparatus, or device, such as a computer-based system, processor-containing system, or other system that can fetch the instructions from the instruction execution system, apparatus, or device and execute the instructions. For the purposes of this description, a "computer-readable medium" can be any means that can contain, store, communicate, propagate, or transport the program for use by or in connection with the instruction execution system, apparatus, or device.
More specific examples (a non-exhaustive list) of the computer-readable medium would include the following: an electrical connection (electronic device) having one or more wires, a portable computer diskette (magnetic device), a Random Access Memory (RAM), a read-only memory (ROM), an erasable programmable read-only memory (EPROM or flash memory), an optical fiber device, and a portable compact disc read-only memory (CDROM). Further, the computer readable medium could even be paper or another suitable medium upon which the above described program is printed, as the program can be electronically captured, via for instance optical scanning of the paper or other medium, then compiled, interpreted or otherwise processed in a suitable manner if necessary, and then stored in a computer memory.
It should be understood that portions of the present invention may be implemented in hardware, software, firmware, or a combination thereof. In the above embodiments, the various steps or methods may be implemented in software or firmware stored in memory and executed by a suitable instruction execution system. For example, if implemented in hardware, as in another embodiment, any one or combination of the following techniques, which are known in the art, may be used: a discrete logic circuit having a logic gate circuit for implementing a logic function on a data signal, an application specific integrated circuit having an appropriate combinational logic gate circuit, a Programmable Gate Array (PGA), a Field Programmable Gate Array (FPGA), or the like.
In the foregoing description of the specification, reference to the description of "one embodiment/example," "another embodiment/example," or "certain embodiments/examples," etc., means that a particular feature, structure, material, or characteristic described in connection with the embodiment or example is included in at least one embodiment or example of the invention. In this specification, schematic representations of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the particular features, structures, materials, or characteristics described may be combined in any suitable manner in any one or more embodiments or examples.
While embodiments of the present invention have been shown and described, it will be understood by those of ordinary skill in the art that: various changes, modifications, substitutions and alterations can be made to the embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the claims and their equivalents.
While the preferred embodiments of the present invention have been illustrated and described, it will be understood by those skilled in the art that various changes in form and details may be made therein without departing from the spirit and scope of the invention as defined by the appended claims.
Claims (10)
1. A method for measuring operation parameters of a three-phase asymmetric converter is characterized by comprising the following steps:
determining the commutation voltage of each converter valve of the converter according to the three-phase voltage at the AC side of the converter, and further determining the synchronous phase of the phase-locked loop of the DC system according to the commutation voltage;
determining a fundamental wave positive and negative sequence component and a third harmonic positive and negative sequence component of the commutation voltage, and determining commutation voltage zero crossing point offset of each converter valve of the converter according to the fundamental wave positive and negative sequence component, the third harmonic positive and negative sequence component and the synchronous phase;
acquiring a trigger angle instruction value output by a direct current system, and determining an actual trigger angle and a conduction delay angle of each converter valve of the converter according to the trigger angle instruction value and the zero-crossing offset of the commutation voltage;
acquiring a direct current component and a second harmonic component of direct current, and obtaining a conversion angle of each converter valve of the converter according to the fundamental wave positive and negative sequence component, the third harmonic positive and negative sequence component, the direct current component and the second harmonic component;
and determining a converter switching function model according to the actual trigger angle, the conduction delay angle and the phase change angle, and further obtaining converter operating parameters according to the switching function model.
2. The method according to claim 1, wherein the step of determining the commutation voltage of each converter valve of the converter according to the three-phase voltage at the ac side of the converter, and further determining the synchronous phase of the phase-locked loop of the dc system according to the commutation voltage, specifically comprises:
the method comprises the steps of obtaining three-phase voltage on the alternating current side of the converter, and obtaining the conversion voltage of each converter valve of the converter after carrying out linear conversion on the three-phase voltage;
performing Clark transformation on the commutation voltage to obtain a first component and a second component of the commutation voltage;
and determining the synchronous phase of the direct current system phase-locked loop according to the first component and the second component.
3. A method according to claim 1, wherein the step of determining the fundamental positive and negative sequence component and the third harmonic positive and negative sequence component of the commutation voltage and determining the zero-crossing offset of the commutation voltage for each valve of the converter based on the fundamental positive and negative sequence component, the third harmonic positive and negative sequence component and the synchronous phase comprises:
extracting fundamental wave components and third harmonic components of the commutation voltage, carrying out symmetrical component transformation on the fundamental wave components to obtain fundamental wave positive and negative sequence components of the commutation voltage, and carrying out symmetrical component transformation on the third harmonic components to obtain third harmonic positive and negative sequence components of the commutation voltage;
determining the actual zero crossing point of commutation voltage according to the fundamental wave positive and negative sequence component, the third harmonic positive and negative sequence component and the synchronous phase;
and determining the steady-state zero crossing point of the commutation voltage of each converter valve of the converter under the three-phase balance working condition, and obtaining the zero crossing offset of the commutation voltage of each converter valve of the converter according to the actual zero crossing point of the commutation voltage and the steady-state zero crossing point of the commutation voltage.
4. The method according to claim 1, wherein the step of determining the actual firing angle and the conduction delay angle of each converter valve of the converter according to the firing angle command value and the zero-crossing offset of the commutation voltage comprises:
if the commutation voltage zero-crossing offset is greater than the trigger angle instruction value, determining that the conduction delay angle is the difference value between the commutation voltage zero-crossing offset and the trigger angle instruction value, and the actual trigger angle is 0; and if the zero-crossing offset of the commutation voltage is less than or equal to the trigger angle instruction value, determining that the actual trigger angle is the difference value between the trigger angle instruction value and the zero-crossing offset of the commutation voltage, and the conduction delay angle is 0.
5. The method according to claim 1, wherein the step of determining a converter switching function model according to the actual firing angle, the conduction delay angle and the commutation angle, and further obtaining the converter operating parameters according to the switching function model specifically comprises:
obtaining a converter switching function component according to the actual trigger angle, the conduction delay angle and the phase change angle;
carrying out Fourier expansion, phase shift processing and superposition processing on the converter switching function component to obtain a converter switching function model;
determining converter operation parameters according to the converter switching function model;
wherein the converter switching function model includes a converter voltage switching function and a converter current switching function.
6. A method according to claim 5, wherein the converter switching function component comprises a fundamental component, a correction component and a commutation component.
7. A method according to claim 5, wherein the converter operation parameters include a converter DC side harmonic voltage and a converter injection harmonic current into an AC system, and the step of determining the converter operation parameters according to the converter switching function model comprises:
determining the harmonic voltage of the direct current side of the converter according to the voltage switching function and the three-phase voltage;
and determining the harmonic current injected into the alternating current system by the converter according to the current switching function and the direct current.
8. A three-phase asymmetric transverter operating parameter survey system characterized by, includes:
the synchronous phase determining module is used for determining the commutation voltage of each converter valve of the converter according to the three-phase voltage at the AC side of the converter, and further determining the synchronous phase of the direct-current system phase-locked loop according to the commutation voltage;
the zero crossing point offset determining module is used for determining a fundamental wave positive and negative sequence component and a third harmonic positive and negative sequence component of the commutation voltage and determining the commutation voltage zero crossing point offset of each converter valve of the converter according to the fundamental wave positive and negative sequence component, the third harmonic positive and negative sequence component and the synchronous phase;
the actual trigger angle and conduction delay angle determining module is used for acquiring a trigger angle instruction value output by a direct current system and determining an actual trigger angle and a conduction delay angle of each converter valve of the converter according to the trigger angle instruction value and the zero-crossing offset of the commutation voltage;
the converter angle determining module is used for acquiring a direct current component and a second harmonic component of direct current, and obtaining the converter angle of each converter valve of the converter according to the fundamental wave positive and negative sequence component, the third harmonic positive and negative sequence component, the direct current component and the second harmonic component;
and the operation parameter calculation module is used for determining a converter switching function model according to the actual trigger angle, the conduction delay angle and the phase change angle and further obtaining the converter operation parameters according to the switching function model.
9. An apparatus for measuring operation parameters of a three-phase asymmetric converter, comprising:
at least one processor;
at least one memory for storing at least one program;
when executed by the at least one processor, cause the at least one processor to implement a method of determining operating parameters of a three-phase asymmetric converter as claimed in any one of claims 1 to 7.
10. A computer readable storage medium having stored therein a program executable by a processor, wherein the program executable by the processor is adapted to perform a method of determining an operation parameter of a three-phase asymmetric converter according to any one of claims 1 to 7 when executed by the processor.
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| CN114024305B (en) * | 2021-11-04 | 2024-03-19 | 中国南方电网有限责任公司超高压输电公司广州局 | 50HZ harmonic amplification factor detection method and device for high-voltage direct-current transmission system |
| CN115032450A (en) * | 2022-08-15 | 2022-09-09 | 山东大学 | Harmonic evaluation method of multi-pulse rectifier under non-ideal condition |
| CN115524535A (en) * | 2022-11-24 | 2022-12-27 | 中国科学院合肥物质科学研究院 | Converter direct current side harmonic analysis method and device under asymmetric triggering and medium |
| CN115524535B (en) * | 2022-11-24 | 2023-03-10 | 中国科学院合肥物质科学研究院 | Converter direct current side harmonic analysis method and device under asymmetric triggering and medium |
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