CN112001059A - Flexible direct current converter valve sub-module broadband model establishing method and device - Google Patents
Flexible direct current converter valve sub-module broadband model establishing method and device Download PDFInfo
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Abstract
The invention discloses a method and a device for establishing a broadband model of a flexible direct current converter valve sub-module. The method comprises the following steps: splitting a flexible direct current converter valve submodule to be analyzed into an active device and a passive device; respectively measuring impedance characteristic data of each active device and each passive device by using an impedance analyzer; respectively obtaining rational function expressions for fitting the impedance characteristics of the active devices and the passive devices according to the measured impedance characteristic data of the active devices and the passive devices; respectively determining component broadband models corresponding to the active components and the passive components according to the rational function expressions; and synthesizing component broadband models respectively corresponding to each active device and each passive device to obtain a broadband model of the flexible direct current converter valve sub-module to be analyzed, wherein the broadband model of the flexible direct current converter valve sub-module to be analyzed is formed by combining an RL series circuit, a CG parallel circuit and an RLCG series-parallel circuit. The method is quick and accurate in establishing the broadband model, and improves the simulation accuracy and efficiency.
Description
Technical Field
The invention relates to the technical field of converter valve sub-module broadband modeling, in particular to a flexible direct current converter valve sub-module broadband model establishing method and device.
Background
At present, few modeling researches on key equipment and components of the flexible direct current converter valve are conducted at home and abroad. Among the studies that have been conducted, the equivalent circuit model is most commonly used. The equivalent circuit model is a physical model which is established by calculating the corresponding resistance, capacitance and inductance of the element or equipment according to the size, material, structure and the like of the element or equipment and then according to the internal electrical connection relation. The method has the advantages that each element has physical significance and is convenient for guiding optimization design; the disadvantage is the poor accuracy of such models at high frequencies.
Therefore, when the transient performance of the power system is simulated, the model precision of key equipment and components of the flexible direct current converter valve cannot meet the simulation requirement, and the accuracy of the simulation result cannot meet the transient performance analysis requirement of the power system.
Disclosure of Invention
Aiming at the technical problems, the invention provides a method and a device for establishing a broadband model of a sub-module of a flexible direct current converter valve, so as to solve the problem that the model precision of key equipment and components of the flexible direct current converter valve cannot meet the simulation requirement in the transient performance simulation of a power system in the prior art.
In a first aspect, the invention provides a method for establishing a broadband model of a flexible direct current converter valve sub-module, which comprises the following steps:
splitting a flexible direct current converter valve submodule to be analyzed into an active device and a passive device;
respectively measuring impedance characteristic data of each active device and each passive device by using an impedance analyzer;
obtaining a rational function expression for fitting the impedance characteristic of the active device or the passive device according to the measured impedance characteristic data of the active device or the passive device;
determining a component broadband model corresponding to each active device or passive device according to each rational function expression, wherein the component broadband model comprises an RL series circuit, a plurality of CG parallel circuits and a plurality of RLCG series-parallel circuits;
and synthesizing component broadband models corresponding to the active devices or the passive devices to obtain a broadband model of the flexible direct current converter valve sub-module to be analyzed, wherein the broadband model of the flexible direct current converter valve sub-module to be analyzed is formed by combining an RL series circuit, a CG parallel circuit and an RLCG series-parallel circuit.
In a second aspect, the present invention provides a device for establishing a wideband model of a flexible dc converter valve sub-module, including:
the impedance characteristic data acquisition module is used for acquiring impedance characteristic data of each active device and each passive device measured by the impedance analyzer; the method comprises the steps that a flexible direct current converter valve submodule to be analyzed is divided into an active device and a passive device;
the component broadband model determining module is used for respectively obtaining rational function expressions for fitting the impedance characteristics of the active devices and the passive devices according to the measured impedance characteristic data of the active devices and the passive devices;
respectively determining component broadband models corresponding to the active devices and the passive devices according to the rational function expressions, wherein the component broadband models comprise an RL series circuit, a plurality of CG parallel circuits and a plurality of RLCG series-parallel circuits;
the device comprises a flexible direct current converter valve sub-module broadband model determining module, a broadband model analyzing module and a broadband model analyzing module, wherein the flexible direct current converter valve sub-module broadband model determining module is used for integrating component broadband models corresponding to active devices and passive devices to obtain a broadband model of the flexible direct current converter valve sub-module to be analyzed, and the broadband model of the flexible direct current converter valve sub-module to be analyzed comprises an RL series circuit, a CG parallel circuit and an RLCG series-parallel circuit.
The method and the device for establishing the broadband model of the flexible direct current converter valve sub-module can quickly and accurately establish the broadband model of the converter valve sub-module required by the transient performance simulation of the power system, so that the accuracy and the efficiency of the transient performance simulation of the power system are improved.
Drawings
A more complete understanding of exemplary embodiments of the present invention may be had by reference to the following drawings in which:
fig. 1 is a schematic flow chart of a method for establishing a wideband model of a sub-module of a flexible direct-current converter valve according to an embodiment of the present invention;
fig. 2 is a schematic composition diagram of a device for establishing a wideband model of a sub-module of a flexible direct-current converter valve according to an embodiment of the present invention;
fig. 3 is a schematic wiring diagram of components and an impedance analyzer of a converter valve submodule in the flexible direct-current converter valve submodule broadband model establishing method according to the embodiment of the invention;
fig. 4 is a schematic circuit diagram of a method for establishing a wideband model of a sub-module of a flexible dc converter valve according to an embodiment of the present invention;
fig. 5 is another schematic circuit diagram in the method for establishing a wideband model of a sub-module of a flexible dc converter valve according to an embodiment of the present invention;
fig. 6 is a schematic circuit diagram of another method for establishing a wideband model of a sub-module of a flexible dc converter valve according to an embodiment of the present invention;
fig. 7 is a wideband model established for a flexible dc converter valve sub-module by the flexible dc converter valve sub-module wideband model establishing method according to the embodiment of the present invention;
fig. 8 is a schematic flow chart of a method for establishing a wideband model of a sub-module of a flexible dc converter valve according to another embodiment of the present invention.
Detailed Description
The exemplary embodiments of the present invention will now be described with reference to the accompanying drawings, however, the present invention may be embodied in many different forms and is not limited to the embodiments described herein, which are provided for complete and complete disclosure of the present invention and to fully convey the scope of the present invention to those skilled in the art. The terminology used in the exemplary embodiments illustrated in the accompanying drawings is not intended to be limiting of the invention. In the drawings, the same units/elements are denoted by the same reference numerals.
Unless otherwise defined, terms (including technical and scientific terms) used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. Further, it will be understood that terms, such as those defined in commonly used dictionaries, should be interpreted as having a meaning that is consistent with their meaning in the context of the relevant art and will not be interpreted in an idealized or overly formal sense.
The following are some definitions of terms:
RLCG series-parallel circuit: the equivalent circuit comprises a plurality of conductance elements, resistance elements, inductance elements and capacitance elements which are connected in series and in parallel.
The flexible direct current converter valve submodule consists of elements such as a leakage resistor, an energy storage capacitor, a copper bar, an IGBT (only the IGBT in an off state is concerned here) and the like. These devices can be broadly classified into two broad categories, active devices and passive devices.
As shown in fig. 1, the method for establishing a broadband model of a flexible dc converter valve sub-module according to the embodiment of the present invention includes the following steps:
step S100: splitting a flexible direct current converter valve submodule to be analyzed into an active device and a passive device;
step S200: respectively measuring impedance characteristic data of each active device and each passive device by using an impedance analyzer;
respectively obtaining rational function expressions for fitting the impedance characteristics of the active devices and the passive devices according to the measured impedance characteristic data of the active devices and the passive devices;
respectively determining component broadband models corresponding to the active devices and the passive devices according to the rational function expressions, wherein the component broadband models comprise an RL series circuit, a plurality of CG parallel circuits and a plurality of RLCG series-parallel circuits;
step S300: and synthesizing component broadband models corresponding to the active devices and the passive devices to obtain a broadband model of the flexible direct current converter valve sub-module to be analyzed, wherein the broadband model of the flexible direct current converter valve sub-module to be analyzed is formed by combining an RL series circuit, a CG parallel circuit and an RLCG series-parallel circuit.
The obtaining of the rational function expressions for fitting the impedance characteristics of the active devices and the passive devices respectively according to the measured impedance characteristic data of the active devices and the passive devices includes:
performing rational approximation on the impedance characteristic of the active device or the passive device by using a vector matching method according to the measured impedance characteristic data of the active device or the passive device to obtain a rational function expression F(s) for representing the impedance characteristic of the active device or the passive device in a wide frequency range:
wherein the pole pkAnd its corresponding reserve reskIs a real or conjugate complex pair;
e is a first order coefficient;
d is a constant term;
n is the number of pole points;
the fitting accuracy of the rational function expression F(s) is verified through recursive convolution so as to reduce the fitting error.
Determining component broadband models corresponding to the active devices and the passive devices respectively according to the rational function expressions, wherein the component broadband models comprise:
obtaining a constant term and a first-order term F by decomposing from a rational function expression F(s) for representing the impedance characteristics of the active device or the passive device in a wide frequency band range1(s)；
Determining an RL series circuit corresponding to a constant term and a primary term, wherein the resistance value in the RL series circuit is a constant term d, and the inductance value in the RL series circuit is a primary term coefficient e;
the RL series circuit is the RL series circuit in the element wideband model of the active device or the passive device.
Determining component broadband models corresponding to the active devices and the passive devices respectively according to the rational function expressions, wherein the component broadband models comprise:
real pole terms F(s) corresponding to all M real poles are solved from rational function expressions F(s) for representing impedance characteristics of the active device or the passive device in a wide frequency band range2k(s)；
Determining the pole p of each real numberkAnd residue reskCombining corresponding CG parallel circuits, wherein the capacitance value C in the CG parallel circuits is 1/reskThe conductance value G in the CG parallel circuit is-C Pk；
The CG parallel circuits corresponding to all M real number poles are a plurality of CG parallel circuits in the component broadband model of the active device or the passive device;
in the component broadband model of the active device or the passive device, the CG parallel circuits corresponding to the M real number poles are in series connection.
Determining component broadband models corresponding to the active devices and the passive devices respectively according to the rational function expressions, wherein the component broadband models comprise:
a conjugate complex pole item F corresponding to all (N-M)/2 pairs of conjugate complex poles is solved from a rational function expression F(s) for representing the impedance characteristics of the active device or the passive device in a wide frequency band range3k(s)；
Determining the pole p of each pair of conjugate complex numbers1And p2And residue res1And res2Combining a corresponding one of the RLCG series-parallel circuits, the RLCG series-parallel circuit including a first loop and a second loop connected in parallel; in the first loop, the inductance LCAnd a resistor RCAre connected in series; in the second loop, a capacitor CCAnd conductance GCParallel connection; inductor LCResistance RCCapacitor CCAnd conductance GCThe value of (d) is determined according to the following formula:
all the RLCG series-parallel circuits corresponding to the (N-M)/2 pairs of conjugate complex poles are a plurality of RLCG series-parallel circuits in the component broadband model of the active device or the passive device;
in the component broadband model of the active device or the passive device, each RLCG series-parallel circuit corresponding to (N-M)/2 pairs of conjugate complex poles is in series connection.
The flexible direct current converter valve submodule to be analyzed is split into an active device and a passive device, and the method comprises the following steps:
the active device comprises a thyristor or an IGBT module;
the passive device comprises a resistance unit, a capacitance unit or a copper bar unit.
The method for respectively measuring the impedance characteristic curves of each active device and each passive device by using the impedance analyzer comprises the following steps:
measuring an impedance characteristic curve for the IGBT module in an off state;
selecting a coaxial cable as a connecting lead to connect two ends of the tested device with the impedance analyzer respectively, wherein the coaxial cable is grounded at the tail end of the shielding layer.
The method for respectively measuring the impedance characteristic curves of each active device and each passive device by using the impedance analyzer comprises the following steps:
and generating frequency sweep signals at equal logarithmic intervals in the range of 50Hz to 5MHz to obtain impedance characteristic data and/or impedance characteristic curves of the tested device at 100 frequency points.
The obtaining of the rational function expression for fitting the impedance characteristic curve of the active device or the passive device according to the measured impedance characteristic curve of the active device or the passive device includes:
and calculating the convolution of the rational function expression in the time domain by using a recursive convolution method to verify the fitting precision of the rational function expression for fitting the impedance characteristic curve of the active device or the passive device so as to reduce the fitting error.
In summary, according to the method for establishing the broadband model of the flexible direct current converter valve sub-module, the flexible direct current converter valve sub-module is divided into a plurality of components according to the electrical connection relationship; respectively determining a component broadband model corresponding to each component; and combining all the component broadband models according to the electrical connection relation to form a sub-module broadband model corresponding to the flexible direct current converter valve sub-module.
As shown in fig. 2, the device for establishing a broadband model of a flexible dc converter valve sub-module according to an embodiment of the present invention includes:
an impedance characteristic data acquisition module 10, configured to acquire impedance characteristic data of each active device and each passive device measured by an impedance analyzer; the method comprises the steps that a flexible direct current converter valve submodule to be analyzed is divided into an active device and a passive device;
the component broadband model determining module 20 is configured to obtain rational function expressions for fitting impedance characteristics of the active devices and the passive devices according to the measured impedance characteristic data of the active devices and the passive devices;
respectively determining component broadband models corresponding to the active devices and the passive devices according to the rational function expressions, wherein the component broadband models comprise an RL series circuit, a plurality of CG parallel circuits and a plurality of RLCG series-parallel circuits;
the flexible direct current converter valve sub-module broadband model determining module 30 is used for integrating the component broadband models corresponding to the active devices and the passive devices to obtain a broadband model of the flexible direct current converter valve sub-module to be analyzed, wherein the broadband model of the flexible direct current converter valve sub-module to be analyzed comprises an RL series circuit, a CG parallel circuit and an RLCG series-parallel circuit.
The flexible direct current converter valve sub-module broadband model establishing device of the embodiment has the same technical concept, technical scheme and technical effect as the flexible direct current converter valve sub-module broadband model establishing method, and is not repeated here.
Specifically, determining a component broadband model corresponding to a component of any flexible direct current converter valve submodule comprises the following steps:
(1) measuring impedance characteristic curve of component
Frequency domain measurement techniques were developed from linear system frequency domain analysis. The frequency sweep measuring method in the frequency domain measuring technology is to obtain the frequency response characteristic of the element to be measured by an impedance analyzer by utilizing a sinusoidal signal which sweeps in a certain frequency range according to a certain rule along with time.
When impedance characteristic curves of all components of the flexible direct current converter valve submodule are measured respectively, if some components cannot be directly connected to an impedance analyzer, the impedance analyzer and the tested components need to be connected through connecting leads to form a test loop. In order to ensure the consistency of the test loop, as shown in fig. 3, a coaxial cable is generally selected as a connection lead to connect two ends of the device under test to the impedance analyzer, wherein the coaxial cable is grounded at the end of the shielding layer.
After the measurement is started, the impedance analyzer generates a sweep frequency signal, and sine waves with different frequencies are sequentially applied to the tested component through the coaxial cable; and meanwhile, the response signal of the tested component is transmitted back to the impedance analyzer through the coaxial cable. The impedance analyzer obtains amplitude-frequency and phase-frequency characteristic data of the tested component at corresponding frequency points by analyzing the sweep frequency signal and the response signal of the tested component, and outputs the amplitude-frequency and phase-frequency characteristic data which can be used for drawing an impedance characteristic curve.
Since the IGBT module inside the converter valve sub-module is an active device, the impedance characteristic curve of the IGBT module is measured in the off-state.
(2) Fitting impedance characteristic curve of component
Specifically, amplitude-frequency and phase-frequency characteristic data of components of the submodule of the flexible direct current converter valve measured by the impedance analyzer are a series of discrete data points related to frequency. For example, in the range of 50Hz to 5MHz, the frequency sweep signals are generated at equal logarithmic intervals, and the impedance characteristics of the tested device at 100 frequency points can be obtained, wherein each data point represents the impedance value of the element at one frequency.
And fitting the discrete data points to obtain a functional expression (namely F (s)) of the impedance characteristic of the component in the wide frequency band range. It should be noted that, since the impedance characteristic is expressed by two parameter values, i.e., the amplitude value and the phase angle, the functional expression obtained by fitting is a complex form.
Specifically, rational approximation is carried out on amplitude-frequency and phase-frequency characteristic data of the component, so as to obtain a rational function expression for representing the impedance characteristic of the tested component in a wide frequency band range. There are many methods for performing rational approximation on amplitude-frequency and phase-frequency characteristic data, and among them, a Vector matching method (VF for short) is an efficient and accurate method. The VF method comprises the following specific steps:
the rational function expression of the impedance characteristic of any component of the converter valve submodule in the wide frequency band range is set as follows:
in the formula (1), the reaction mixture is,
pole pkAnd its corresponding reserve reskIs made ofA pair of numbers or conjugated complex numbers;
the first term e and the constant term d are real numbers;
n is the number of pole points.
It should be noted that the more the number N of initial poles selected in the fitting process, the higher the accuracy of the curve obtained by fitting, but the more complex the model is, the lower the simulation efficiency may become. Therefore, the adaptive learning function in the MATLAB neural network toolbox is adopted to select the pole number N in rational approximation.
The adaptive process is a process that continuously approaches the target. The path it follows is represented by a mathematical model, called an adaptive algorithm. Training the sample by adopting a minimum mean square error algorithm (namely LMS algorithm) in the self-adaptive algorithm, and continuously adjusting the weight w and the threshold value b to ensure that the fitted pole number continuously approaches the optimal result so as to determine the proper fitting order. Specifically, each input takes different pole numbers (the real number part of the pole is selected according to the pole number in the frequency range at equal logarithmic intervals, the imaginary part takes one tenth of the real number to obtain a group of conjugate complex numbers), the error of the fitting result and the measured data is used as a criterion, and the optimal pole number N or the proper fitting order is determined through self-adaptive learning.
After determining the number N of poles, selecting a characteristic point, such as a turning point, of an amplitude-frequency or phase-frequency curve in the measurement frequency range, and taking a pair of plural poles at the characteristic point
And assuming an unknown function σ(s):
multiplying the function σ(s) by F(s), where the poles are
Obtaining:
from formulas (1) and (3):
it should be understood that the number of characteristic points of the broadband model of the component corresponding to each component is different. Initial pole
May also be chosen at regular intervals on a logarithmic scale.
Specifically, f(s) is a complex number, that is, | Z |. θ, s |. j ω.
Wherein | Z | is the amplitude of the corresponding frequency point, and θ is the phase angle of the corresponding frequency point.
Carrying in (4) amplitude-frequency and phase-frequency characteristic data (such as discrete data points at 100 frequency points) of components of the converter valve submodule measured by using an impedance analyzer, and obtaining a group of linear equations after finishing:
Ax＝b (5)
solving the linear equation set (5) can obtain the unknowns e, d,
And reskFurther solving the linear equation system to solve the pole p of F(s)k。
By this point, vector matching has been completed, resulting in a fitting function of the measured data.
According to the rational function expression F(s) of the impedance characteristic of the component in the wide frequency band range, the impedance characteristic of the component in the specific frequency range can be determined, namely, the impedance characteristic curve of the component is obtained through fitting.
Further, the rational function expression f(s) obtained by vector matching can be used for verifying the fitting accuracy by recursive convolution so as to reduce the fitting error.
Since the function obtained by the vector matching method is in the frequency domain, the time domain function h (t) in the form of an exponential sum can be obtained by converting the fitted function from the frequency domain to the time domain.
In particular, for an arbitrary excitation, its response in the time domain is required, simply by convolving the excitation with a rational function in the time domain, i.e.
Since the function h (t) of the component in the wide frequency band range can be written in the form of a plurality of exponential function sums, the integral calculation of the formula (9) can be performed by a recursive convolution method.
Let h (t) ke-α(t-T)Then the formula (9) is changed to
If f (T) is known for the values at times T and T + Δ T, s (T) can be derived from the value s (T- Δ T) of the previous time step, recursively as equation (11):
s(t)＝ms(t-At)+pf(t-T)+qf(t-T-Δt) (11)
in the formula (11), Δ t is a calculation step; m, p, q are all constants, and
in the above, the rational function approximation error can be reduced by using the calculation result of the recursive convolution in the time domain. In particular, the function resulting from the vector matching is obtained by fitting the data measured by the instrument in the frequency domain. However, in a practical system, the transient process in the time domain is focused, so that in order to reduce the error of the obtained function, the accuracy of the fitting function in the time domain can be verified through the conversion between the time domain and the frequency domain and the response of the actual excitation in the time domain. When the response in the time domain has a large error, the frequency domain function can be adjusted in reverse by improving the time domain function, so that the fitting error is reduced.
In the above steps, a vector matching method and a self-adaptive learning function are used to obtain an optimal fitting result with a fitting order of K; the convolution of the measured parameters is calculated by a recursive convolution method, and the function in the time domain is corrected by comparing the response of the actual excitation in the time domain, so that the error between the fitted impedance characteristic curve in the frequency domain and the measured impedance characteristic curve is smaller.
(3) Determining component broadband model
Splitting the rational function expression F(s) according to the rational function expression F(s) of the impedance characteristics of the component, and performing circuit equivalence on each split item to obtain a component broadband model.
After the processing of the steps, N poles of the formula (1) all fall on the left half plane.
In the N poles of the rational function expression f(s) of the impedance characteristic of the device in the wide frequency band range, as shown in formula (1), the first M poles are real poles, the last (N-M) poles are complex conjugate poles, and two poles that are conjugate to each other are adjacent, so that the rational function f(s) has (N-M)/2 pairs of complex conjugate poles and residue. These (N-M)/2 pairs of conjugate complex poles and residuals can be expressed as:
in formula (6): k ═ M +1, M +2, …, (N-M)/2;
p′kand p ″)kRespectively a real part and an imaginary part of a conjugate complex pole;
res′kand res ″)kRespectively a real part and an imaginary part of the conjugate complex number residue;
subscripts 1 and 2 in equations (6) and (7) indicate that both are adjacent poles or residuals.
Therefore, the rational function expression F(s) of the impedance characteristic of the component in the wide frequency band range, as shown in formula (1), can be decomposed into a real number term and a first order term F1(s) real pole term F2k(s) and the conjugate complex pole term F3k(s) is represented by formula (8):
wherein:
F1(s)＝se+d (8-1)
the real term and the first order term part of the equation (1), that is, the equation (8-1) may be equivalent using a series circuit of a resistive element and an inductive element as shown in fig. 4.
Specifically, F1(s)＝se+d，F1(s) is an expression of impedance, i.e. voltage divided by current, i.e. U/I + d + j ω e + d; for an inductive element, the impedance is j ω L, so it can be equivalently an inductance in series with a resistance.
Specifically, if the voltage across the series circuit is U(s) and the current flowing through the element is I(s), the equivalent impedance Z of the circuit of FIG. 5 is1(s) is:
comparing equation (12) with equation (8-1), the resistance R and inductance L in the circuit are:
R＝d：
L＝e：
the real pole term part of equation (1), i.e., equation (8-2), may be equivalent with a CG parallel circuit in which a conductance element (i.e., a resistance element) and a capacitance element are connected in parallel as shown in fig. 5.
Taking one of the real poles p and the corresponding residue res as an example, the equivalent impedance Z of the circuit of fig. 5 is illustrated2(s) is:
comparing equation (8-2) with equation (13), it can be found that:
the real pole p and the corresponding residue res are substituted into equation (14) to obtain the capacitance C in the circuit of FIG. 5RAnd conductance GR。
The conjugate complex pole term part of equation (1), i.e., equation (8-3), may be equivalent with an RLCG series-parallel circuit of a conductance element, a resistance element, an inductance element, and a capacitance element as shown in fig. 6.
With one pair of conjugate complex poles p1And p2And corresponding reserve res1And res2The description is given for the sake of example. Equivalent impedance Z of the circuit of FIG. 63(s) is
Comparing equation (15) and equation (8-3), it is possible to obtain:
pole p of conjugate complex number1And p2And corresponding reserve res1And res2The capacitance C in the RLCG circuit of FIG. 6 can be obtained by substituting formula (16)CInductor LCResistance RCAnd the conductance value GC. In FIG. 6 including a second in parallelA first circuit and a second circuit; in the first loop, the inductance LCAnd a resistor RCAre connected in series; in the second loop, a capacitor CCAnd conductance GCParallel connection;
since then, equivalent circuits have been established for the real term and the first order part, respectively, for a single real pole and for a pair of conjugated complex poles.
Referring to the above steps, for M real number poles in equation (8), sub-equivalent parallel circuits (i.e., each CG parallel circuit) of the corresponding conductance element and capacitance element can be obtained respectively;
furthermore, in the rational function expression, all pole parts in the real pole term are in an accumulation relation; the M sub-equivalent parallel circuits are in series connection when the subsequent local synthesis is carried out.
Referring to the above steps, for the (N-M)/2 pairs of conjugate complex poles in equation (8), the sub-equivalent series-parallel circuits (i.e., each RLCG series-parallel circuit) of the corresponding conductance element, resistance element, inductance element and capacitance element can be obtained.
Further, the (N-M)/2 sub equivalent series-parallel circuits are in series connection when the subsequent local synthesis is carried out.
And finally, connecting all the sub equivalent circuits through local synthesis to obtain an RLCG series-parallel circuit corresponding to the component as a component broadband model corresponding to a rational function expression F(s) of the impedance characteristic of the component.
Specifically, according to the electrical connection relation, combine all components and parts wide band models, form the sub-module wide band model that flexible direct current converter valve sub-module corresponds, include:
and obtaining a broadband model of the flexible direct current converter valve sub-module according to component broadband models corresponding to all components of the flexible direct current converter valve sub-module through global synthesis.
Specifically, according to the structural characteristics, the electrical connection relationship and the like, a broadband model of an IGBT module (which is an active device) of the flexible direct current converter valve is connected with broadband models of other passive devices, and the broadband model of the flexible direct current converter valve sub-module in a turn-off state can be obtained.
By adopting the method for establishing the broadband model of the flexible direct current converter valve sub-module shown in fig. 7, the broadband model established for a certain flexible direct current converter valve sub-module is the equivalent circuit shown in fig. 8. The four-bar-type bus bar comprises 4 bus bar units (comprising a resistor and a capacitor series-parallel circuit), a resistor unit (comprising a resistor and a capacitor series-parallel circuit), a capacitor unit (comprising a resistor and a capacitor series-parallel circuit) and an IGBT module. The IGBT module is an element formed by connecting an IGBT and a diode in anti-parallel.
The invention has been described above by reference to a few embodiments. However, as is known to those skilled in the art, other embodiments than the ones disclosed above are equally possible within the scope of this invention, as defined by the appended patent examples.
As will be appreciated by one skilled in the art, embodiments of the present application may be provided as a method, system, or computer program product. Accordingly, the present application may take the form of an entirely hardware embodiment, an entirely software embodiment or an embodiment combining software and hardware aspects. Furthermore, the present application may take the form of a computer program product embodied on one or more computer-usable storage media (including, but not limited to, disk storage, CD-ROM, optical storage, and the like) having computer-usable program code embodied therein.
The present application is described with reference to flowchart illustrations and/or block diagrams of methods, apparatus (systems), and computer program products according to embodiments of the application. It will be understood that each flow and/or block of the flow diagrams and/or block diagrams, and combinations of flows and/or blocks in the flow diagrams and/or block diagrams, can be implemented by computer program instructions. These computer program instructions may be provided to a processor of a general purpose computer, special purpose computer, embedded processor, or other programmable data processing apparatus to produce a machine, such that the instructions, which execute via the processor of the computer or other programmable data processing apparatus, create means for implementing the functions specified in the flowchart flow or flows and/or block diagram block or blocks.
These computer program instructions may also be stored in a computer-readable memory that can direct a computer or other programmable data processing apparatus to function in a particular manner, such that the instructions stored in the computer-readable memory produce an article of manufacture including instruction means which implement the function specified in the flowchart flow or flows and/or block diagram block or blocks.
These computer program instructions may also be loaded onto a computer or other programmable data processing apparatus to cause a series of operational steps to be performed on the computer or other programmable apparatus to produce a computer implemented process such that the instructions which execute on the computer or other programmable apparatus provide steps for implementing the functions specified in the flowchart flow or flows and/or block diagram block or blocks.
Finally, it should be noted that: the above embodiments are only for illustrating the technical solutions of the present invention and not for limiting the same, and although the present invention is described in detail with reference to the above embodiments, those of ordinary skill in the art should understand that: modifications and equivalents may be made to the embodiments of the invention without departing from the spirit and scope of the invention, which is to be covered by the claims.
Generally, all terms used in the claims are to be interpreted according to their ordinary meaning in the technical field, unless explicitly defined otherwise herein. All references to "a// the [ device, component, etc ]" are to be interpreted openly as at least one instance of a device, component, etc., unless explicitly stated otherwise. The steps of any method disclosed herein do not have to be performed in the exact order disclosed, unless explicitly stated.
Claims (10)
1. A flexible direct current converter valve sub-module broadband model building method is characterized by comprising the following steps:
splitting a flexible direct current converter valve submodule to be analyzed into an active device and a passive device;
respectively measuring impedance characteristic data of each active device and each passive device by using an impedance analyzer;
respectively obtaining rational function expressions for fitting the impedance characteristics of the active devices and the passive devices according to the measured impedance characteristic data of the active devices and the passive devices;
respectively determining component broadband models corresponding to the active devices and the passive devices according to the rational function expressions, wherein the component broadband models comprise an RL series circuit, a plurality of CG parallel circuits and a plurality of RLCG series-parallel circuits;
and synthesizing component broadband models corresponding to the active devices and the passive devices to obtain a broadband model of the flexible direct current converter valve sub-module to be analyzed, wherein the broadband model of the flexible direct current converter valve sub-module to be analyzed comprises an RL series circuit, a CG parallel circuit and an RLCG series-parallel circuit.
2. The method of claim 1,
the obtaining of the rational function expressions for fitting the impedance characteristics of the active devices and the passive devices respectively according to the measured impedance characteristic data of the active devices and the passive devices includes:
performing rational approximation on the impedance characteristic of the active device or the passive device by using a vector matching method according to the measured impedance characteristic data of the active device or the passive device to obtain a rational function expression F(s) for representing the impedance characteristic of the active device or the passive device in a wide frequency range:
wherein the pole pkAnd its corresponding reserve reskIs a real or conjugate complex pair;
e is a first order coefficient;
d is a constant term;
n is the number of pole points;
the fitting precision of the rational function expression F(s) is verified through recursive convolution, and fitting errors are reduced.
3. The method of claim 1,
determining component broadband models corresponding to the active devices and the passive devices respectively according to the rational function expressions, wherein the component broadband models comprise:
obtaining a constant term and a first-order term F by decomposing from a rational function expression F(s) for representing the impedance characteristics of the active device or the passive device in a wide frequency band range1(s)；
Determining an RL series circuit corresponding to a constant term and a primary term, wherein the resistance value in the RL series circuit is a constant term d, and the inductance value in the RL series circuit is a primary term coefficient e;
the RL series circuit is the RL series circuit in the element wideband model of the active device or the passive device.
4. The method of claim 1,
determining component broadband models corresponding to the active devices and the passive devices respectively according to the rational function expressions, wherein the component broadband models comprise:
real pole terms F(s) corresponding to all M real poles are solved from rational function expressions F(s) for representing impedance characteristics of the active device or the passive device in a wide frequency band range2k(s)；
Determining the pole p of each real numberkAnd residue reskCombining corresponding CG parallel circuits, wherein the capacitance value C in the CG parallel circuits is 1/reskThe conductance value G in the CG parallel circuit is-C × pk；
The CG parallel circuits corresponding to all M real number poles are a plurality of CG parallel circuits in the component broadband model of the active device or the passive device;
in the component broadband model of the active device or the passive device, the CG parallel circuits corresponding to the M real number poles are in series connection.
5. The method of claim 1,
determining component broadband models corresponding to the active devices and the passive devices respectively according to the rational function expressions, wherein the component broadband models comprise:
a conjugate complex pole item F corresponding to all (N-M)/2 pairs of conjugate complex poles is solved from a rational function expression F(s) for representing the impedance characteristics of the active device or the passive device in a wide frequency band range3k(s)；
Determining the pole p of each pair of conjugate complex numbers1And p2And residue res1And res2Combining a corresponding one of the RLCG series-parallel circuits, the RLCG series-parallel circuit including a first loop and a second loop connected in parallel; in the first loop, the inductance LCAnd a resistor RCAre connected in series; in the second loop, a capacitor CCAnd conductance GCParallel connection; inductor LCResistance RCCapacitor CCAnd conductance GCThe value of (d) is determined according to the following formula:
all the RLCG series-parallel circuits corresponding to the (N-M)/2 pairs of conjugate complex poles are a plurality of RLCG series-parallel circuits in the component broadband model of the active device or the passive device;
in the component broadband model of the active device or the passive device, each RLCG series-parallel circuit corresponding to (N-M)/2 pairs of conjugate complex poles is in series connection.
6. The method of claim 1,
the flexible direct current converter valve submodule to be analyzed is split into an active device and a passive device, and the method comprises the following steps:
the active device comprises a thyristor or an IGBT module;
the passive device comprises a resistance unit, a capacitance unit or a copper bar unit.
7. The method of claim 1,
the method for respectively measuring the impedance characteristic curves of each active device and each passive device by using the impedance analyzer comprises the following steps:
measuring an impedance characteristic curve for the IGBT module in an off state;
selecting a coaxial cable as a connecting lead to connect two ends of the tested device with the impedance analyzer respectively, wherein the coaxial cable is grounded at the tail end of the shielding layer.
8. The method of claim 1,
the method for respectively measuring the impedance characteristic curves of each active device and each passive device by using the impedance analyzer comprises the following steps:
and generating frequency sweep signals at equal logarithmic intervals in the range of 50Hz to 5MHz to obtain impedance characteristic data and/or impedance characteristic curves of the tested device at 100 frequency points.
9. The method of claim 1,
the obtaining of the rational function expression for fitting the impedance characteristic curve of the active device or the passive device according to the measured impedance characteristic curve of the active device or the passive device includes:
and calculating the convolution of the rational function expression in the time domain by using a recursive convolution method to verify the fitting precision of the rational function expression for fitting the impedance characteristic curve of the active device or the passive device so as to reduce the fitting error.
10. The utility model provides a flexible direct current converter valve submodule piece wide band model building device which characterized in that includes:
the impedance characteristic data acquisition module is used for acquiring impedance characteristic data of each active device and each passive device measured by the impedance analyzer; the method comprises the steps that a flexible direct current converter valve submodule to be analyzed is divided into an active device and a passive device;
the component broadband model determining module is used for respectively obtaining rational function expressions for fitting the impedance characteristics of the active devices and the passive devices according to the measured impedance characteristic data of the active devices and the passive devices;
respectively determining component broadband models corresponding to the active devices and the passive devices according to the rational function expressions, wherein the component broadband models comprise an RL series circuit, a plurality of CG parallel circuits and a plurality of RLCG series-parallel circuits;
the device comprises a flexible direct current converter valve sub-module broadband model determining module, a broadband model analyzing module and a broadband model analyzing module, wherein the flexible direct current converter valve sub-module broadband model determining module is used for integrating component broadband models corresponding to active devices and passive devices to obtain a broadband model of the flexible direct current converter valve sub-module to be analyzed, and the broadband model of the flexible direct current converter valve sub-module to be analyzed comprises an RL series circuit, a CG parallel circuit and an RLCG series-parallel circuit.
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| CN112800647A (en) * | 2021-01-09 | 2021-05-14 | 国网山西省电力公司检修分公司 | Multi-physical-field coupling simulation method and system for GIS isolating switch under different contact states |
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| CN112906330A (en) * | 2021-01-27 | 2021-06-04 | 中国电力科学研究院有限公司 | Broadband modeling method suitable for high-power IGBT |
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