Harmonic circulating current determination method and device based on M3C harmonic circulating current simplified model, electronic equipment and storage medium

Abstract

The invention discloses a harmonic circulating current determination method and device based on an M3C harmonic circulating current simplified model, electronic equipment and a storage medium. The method comprises the following steps: acquiring parameters of an M3C and parameters of a power grid side; wherein the parameters of the M3C element comprise the number of bridge arm full-bridge sub-modules, bridge arm inductance, sub-module capacitance, a sub-module capacitance voltage reference value and closed-loop proportional gain; the parameters of the power grid side comprise a power frequency side frequency, a frequency division side frequency, a power frequency side voltage d-axis component and a frequency division side voltage d-axis component; and according to the parameters of the M3C element and the parameters of the power grid side, based on a preset M3C harmonic circulating current simplified model, determining the harmonic circulating current of the M3C. According to the invention, the efficiency of harmonic circulation determination can be improved.

Description

Technical Field

[0001] The present invention relates to the field of power electronic converters and power system harmonic technology, and in particular to a method based on M 3 C. A harmonic circulating current determination method, device, electronic device and storage medium for a simplified harmonic circulating current model. Background Art

[0002] Modular Multilevel Matrix Converter (M 3 C) has been widely used in the fields of flexible frequency division transmission due to its unique flexible current conversion capability and high power density characteristics. 3 The complex circuit structure and nonlinear dynamic characteristics of M make it the main source of harmonic circulating currents. These harmonic circulating currents not only aggravate the heating, loss and aging problems of devices, but also threaten the safety and stability of the frequency-divided transmission system. Therefore, it is necessary to accurately determine M 3 The effective value of the harmonic circulating current of C is not only an important basis for studying the generation and propagation mechanism of harmonics, but also the key to realizing online monitoring and suppression of harmonics, which helps to significantly improve the safety and reliability of the divided-frequency transmission system.

[0003] In the prior art, a modeling method is usually used to determine M 3 C harmonic circulation, these methods often directly consider all high-order components and complex coupling relationships when building models, aiming to fully characterize M 3 C. Although this method can improve the theoretical integrity of the model and the accuracy of describing harmonic behavior to a certain extent, it greatly increases the complexity of the mathematical model. The model contains a large number of variables and equations that are difficult to simplify, which greatly increases the amount of calculation, resulting in a long solution process and reducing the efficiency of determining the effective value of harmonic circulating current, thus affecting its application effect in actual engineering. Summary of the invention

[0004] The embodiment of the present invention provides a method based on M 3 C. A harmonic circulating current determination method, device, electronic device and storage medium for a harmonic circulating current simplified model. The efficiency of harmonic circulating current determination can be improved by implementing the present invention.

[0005] An embodiment of the present invention provides a method based on M 3 C. A method for determining harmonic circulation current of a simplified harmonic circulation current model, including:

[0006] Get M 3 C parameters and grid side parameters; among them, M 3The parameters of the C component include the number of full-bridge submodules, bridge arm inductance, submodule capacitance, submodule capacitance voltage reference value, and closed-loop proportional gain; the parameters on the grid side include the power frequency side frequency, the frequency division side frequency, the power frequency side voltage d-axis component, and the frequency division side voltage d-axis component;

[0007] According to M 3 The parameters of the C element and the parameters of the grid side are based on the preset M 3 C Simplified model of harmonic circulation, determine M 3 C's harmonic circulation;

[0008] Among them, M is constructed by the following method 3 C harmonic circulation simplified model:

[0009] Get M 3 The circuit topology of C;

[0010] Based on Kirchhoff's voltage law, according to the circuit topology, M is constructed. 3 C basic mathematical model;

[0011] Based on the two-dimensional sequence component algorithm, M is eliminated 3 The high-order ripple components, harmonic components and bridge arm impedance voltage drop in the basic mathematical model of C generate M 3 C two-dimensional sequence component model;

[0012] To M 3 C two-dimensional sequence component model to perform ripple coupling analysis and harmonic coupling analysis, and generate M 3 C ripple coupling model and M 3 C harmonic coupling model;

[0013] Generate a bridge arm voltage expression and a harmonic circulating current expression according to the ripple coupling model and the harmonic coupling model;

[0014] Based on M 3 The power relationship and voltage characteristics of C in steady state are used to simplify the bridge arm voltage expression and generate the simplified bridge arm voltage expression; through the simplified bridge arm voltage expression, the harmonic circulating current expression is simplified to generate M 3 C Simplified model of harmonic circulating current.

[0015] Furthermore, the M 3 C harmonic circulation simplified model, including:

[0016]

[0017] Among them, i cir_RMS is the effective value of harmonic circulating current; ω S is the power frequency side frequency; n is the number of full-bridge submodules in the bridge arm; C is the submodule capacitance; v Crefis the submodule capacitor voltage reference value; K P is the closed-loop proportional gain; ω is the system angular frequency; e d is the voltage effective value coefficient; L arm is the bridge arm inductance; x is the frequency ratio between the power frequency side and the divided frequency side; Q is the reactive power; P is the active power.

[0018] Furthermore, based on Kirchhoff's voltage law, according to the circuit topology, M is constructed. 3 C basic mathematical model, including:

[0019] Based on Kirchhoff's voltage law and according to the circuit topology, a dynamic voltage balance equation, a bridge arm voltage equation and a submodule capacitor voltage dynamic equation are generated;

[0020] According to the dynamic voltage balance equation, bridge arm voltage equation and submodule capacitor voltage dynamic equation, M is constructed. 3 C basic mathematical model;

[0021] Among them, the dynamic voltage balance equation is specifically:

[0022]

[0023] In the formula, is the rate of change of the bridge arm current; I is the bridge arm current matrix; U S is the power frequency system voltage matrix; U L is the voltage matrix of the frequency division system; V is the bridge arm output voltage matrix; v N is the voltage difference between the neutral points of the two systems; B is the bridge arm distribution matrix;

[0024] The bridge arm voltage equation is specifically:

[0025] V=n·M*V c

[0026] Where, M is the bridge arm modulation signal matrix; V c is the submodule capacitance voltage matrix;

[0027] The submodule capacitor voltage dynamic equation is as follows:

[0028]

[0029] In the formula, is the rate of change matrix of the submodule capacitor voltage.

[0030] Furthermore, the M 3C two-dimensional sequence component model, including the two-dimensional sequence component expression of the modulation signal, the corresponding relationship between the phase sequence and the frequency, the definition of the variable order, the two-dimensional sequence component expression of the power frequency system voltage, the two-dimensional sequence component expression of the frequency division system voltage and the two-dimensional sequence component expression of the bridge arm current;

[0031] The two-dimensional sequence component expression of the modulated signal is specifically:

[0032]

[0033] in, is the two-dimensional sequence component of the modulation signal of the power frequency system; ω S is the power frequency angular frequency; PZ is the positive sequence-zero sequence component; is the two-dimensional sequence component of the modulation signal of the frequency division system; ω L is the frequency division angular frequency; ZP is the positive sequence-zero sequence component; It is the positive-sequence-zero-sequence component of the power frequency system modulation signal on the d-axis and q-axis; It is the zero-sequence-positive-sequence component of the modulation signal of the frequency division system on the d-axis and q-axis; is the positive-zero sequence component of the power frequency system voltage on the d-axis and q-axis; is the zero-sequence-positive-sequence component of the divided-frequency system voltage on the d-axis and q-axis;

[0034] The corresponding relationship between the phase sequence and the frequency is specifically:

[0035]

[0036] Among them, Y is the phase sequence variable in the vertical direction; X is the phase sequence variable in the horizontal direction; k Y(X) is the frequency coefficient; P is the positive sequence component; N is the negative sequence component; Z is the zero sequence component;

[0037] The definition of the variable order is specifically:

[0038] Order=|k X |+|k Y |

[0039] Among them, Order is the order of the variable; k X is the frequency coefficient of the frequency division system; k Y is the frequency coefficient of the power frequency system;

[0040] The two-dimensional sequence component expression of the power frequency system voltage is specifically:

[0041]

[0042] in, It is the two-dimensional sequence component representation of the power frequency system voltage;

[0043] The two-dimensional sequence component expression of the frequency division system voltage is specifically:

[0044]

[0045] in, is the two-dimensional sequence component representation of the voltage of the frequency division system;

[0046] The two-dimensional sequence component expression of the bridge arm current is specifically:

[0047]

[0048] in, It is the two-dimensional sequence component representation of the power frequency system current; It is the two-dimensional sequence component representation of the frequency division system current; are the d-axis and q-axis components of the power frequency system current in the rotating coordinate system; are the d-axis and q-axis components of the frequency division system current in the rotating coordinate system.

[0049] Furthermore, the M 3 C ripple coupling model, including;

[0050]

[0051] in, For the frequency (k Y +1)ω S +k X ω L The capacitor voltage ripple, the component under the serial number (Y+P)X; For the frequency k Y ω S +(k X +1)ω L The capacitor voltage ripple, the component under the serial number Y(X+P); For the frequency (k Y +1)ω S -k X ω L The capacitor voltage ripple, the component under the serial number (Y+P)X; For the frequency k Y ω S -(k X -1)ω L The capacitor voltage ripple, the component under the serial number Y (XP); For the frequency k Y ω S +k X ω LThe current component of, the value under the serial number YX; For the frequency k Y ω S -k X ω L The current component of , the value under the serial number YX; Add(·) is the forward coupling operator; Sub(·) is the reverse coupling operator; is the forward coupling transformation term based on the positive-sequence-zero-sequence component of the power frequency modulation signal; is the forward coupling transformation term based on the zero-sequence-positive-sequence component of the frequency division modulation signal; is the reverse coupling transformation term based on the zero-sequence-positive-sequence component of the frequency division modulation signal;

[0052] The M 3 C harmonic coupling model, including:

[0053]

[0054] in, For the frequency k Y ω S +k X ω L The current component of , the value under the serial number (Y+P)X; For the frequency k Y ω S +(k X +1)ω L The current component of, the value under the serial number Y(X+P); For the frequency (k Y +1)ω S -k X ω L The current component of , the value under the serial number (Y+P)X; For the frequency k Y ω S -(k X +1)ω L The current component of, the value under the serial number Y(XP); At the frequency C(k Y ω S +k X ω L ) capacitor voltage ripple, the component under the serial number YX; At the frequency C(k Y ω S -k X ω L )’s capacitor voltage ripple, the component under serial number YX.

[0055] Furthermore, the bridge arm voltage expression includes:

[0056]

[0057] Among them, V z is the bridge arm voltage component; The frequency is 2ω S +ω L , the voltage component of the bridge arm with phase sequence NP; The frequency is 2ω S -ω L , the bridge arm voltage component with phase sequence NN; The frequency is ω S +2ω L , the bridge arm voltage component with phase sequence PN; The frequency is ω S -2ω L , the bridge arm voltage component with phase sequence PP.

[0058] Furthermore, the harmonic circulation expression includes:

[0059]

[0060] in, The frequency is ω 1 The effective value of the harmonic circulating current component; The frequency is ω 2 The effective value of the harmonic circulating current component; The frequency is ω 3 The effective value of the harmonic circulating current component; The frequency is ω 4 The effective value of the harmonic circulating current component.

[0061] Based on the above method embodiment, the present invention provides a corresponding device embodiment.

[0062] An embodiment of the present invention provides a harmonic circulation current determination device based on the M3C harmonic circulation current simplified model, comprising: a parameter acquisition module, a model construction module and a model derivation module;

[0063] The parameter acquisition module is used to obtain M 3 C parameters and grid side parameters; among them, M 3 The parameters of the C component include the number of full-bridge submodules, bridge arm inductance, submodule capacitance, submodule capacitance voltage reference value, and closed-loop proportional gain; the parameters on the grid side include the power frequency side frequency, the frequency division side frequency, the power frequency side voltage d-axis component, and the frequency division side voltage d-axis component;

[0064] The model building module is used to 3The parameters of the C element and the parameters of the grid side are based on the preset M 3 C Simplified model of harmonic circulation, determine M 3 C's harmonic circulation;

[0065] The model derivation module is used to obtain M 3 C circuit topology; Based on Kirchhoff's voltage law, according to the circuit topology, construct M 3 C basic mathematical model; based on two-dimensional sequence component algorithm, eliminating M 3 The high-order ripple components, harmonic components and bridge arm impedance voltage drop in the basic mathematical model of C generate M 3 C two-dimensional sequence component model; for M 3 C two-dimensional sequence component model to perform ripple coupling analysis and harmonic coupling analysis, and generate M 3 C ripple coupling model and M 3 C harmonic coupling model; generating a bridge arm voltage expression and a harmonic circulating current expression according to the ripple coupling model and the harmonic coupling model; based on M 3 The power relationship and voltage characteristics of C in steady state are used to simplify the bridge arm voltage expression and generate the simplified bridge arm voltage expression; through the simplified bridge arm voltage expression, the harmonic circulating current expression is simplified to generate M 3 C Simplified model of harmonic circulating current.

[0066] Based on the above method item embodiments, the present invention provides corresponding electronic device item embodiments.

[0067] An embodiment of the present invention provides an electronic device, including a memory, a processor, and a computer program stored in the memory and executable on the processor. When the processor executes the computer program, the harmonic circulating current determination method based on the M3C harmonic circulating current simplified model described in any one of the above method embodiments can be implemented.

[0068] Based on the above method item embodiments, the present invention provides a corresponding storage medium item embodiment.

[0069] An embodiment of the present invention provides a storage medium having a computer program stored thereon. When the computer program is executed by a processor, the method for determining harmonic circulating current based on the M3C harmonic circulating current simplified model described in any one of the above method embodiments can be implemented.

[0070] Compared with the prior art, the present invention has the following beneficial effects:

[0071] The embodiment of the present invention provides a method based on M 3 C harmonic circulation determination method, device, electronic device and storage medium of the harmonic circulation simplified model. The method obtains M 3C related parameters and grid side parameters, including M 3 The number of bridge arm submodules, inductance, capacitance, voltage reference value and closed-loop proportional gain of the C element, the frequency and voltage d-axis component on the grid side. Based on these parameters, according to the preset M 3 C Simplified model of harmonic circulation, determine M 3 The harmonic circulation of C. Based on the two-dimensional sequence component algorithm, the present invention eliminates M 3 The high-order ripple components, harmonic components and bridge arm impedance voltage drop in the basic mathematical model of C simplify the M 3 C basic mathematical model, thus effectively reducing the complexity of the model. 3 The power relationship and voltage characteristics in the C steady state simplify the bridge arm voltage expression, so that the harmonic circulating current model can determine the harmonic circulating current more quickly while maintaining accuracy, solving the problems of large amount of calculation and long solution process in the prior art, and improving the efficiency of harmonic circulating current determination. BRIEF DESCRIPTION OF THE DRAWINGS

[0072] Figure 1 An embodiment of the present invention provides a method based on M 3 C Flow chart of the harmonic circulating current determination method of the harmonic circulating current simplified model.

[0073] Figure 2 M is provided by an embodiment of the present invention 3 Circuit topology diagram of C.

[0074] Figure 3 The structure M provided by an embodiment of the present invention 3 C Flow diagram of the simplified harmonic circulation model.

[0075] Figure 4 M is provided by an embodiment of the present invention 3 C Harmonic Circulating Current Electromagnetic Transient Simulation and M 3 C. Comparison of the results of determining harmonic circulation using the simplified harmonic circulation model.

[0076] Figure 5 It is a structural schematic diagram of a harmonic circulating current determining device based on the M3C harmonic circulating current simplified model provided by an embodiment of the present invention. DETAILED DESCRIPTION

[0077] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0078] like Figure 1 As shown, an embodiment of the present invention provides a method for determining harmonic circulating current based on the M3C harmonic circulating current simplified model, which at least includes the following steps:

[0079] Step S1: Get M 3 Parameters of C and parameters on the grid side;

[0080] Specifically, M. 3 The parameters of the C component include the number of full-bridge sub-modules in the bridge arm, the bridge arm inductance, the sub-module capacitance, the sub-module capacitance voltage reference value and the closed-loop proportional gain; the parameters on the grid side include the power frequency side frequency, the divided frequency side frequency, the power frequency side voltage d-axis component and the divided frequency side voltage d-axis component.

[0081] Step S2: According to M 3 The parameters of the C element and the parameters of the grid side are based on the preset M 3 C Simplified model of harmonic circulation, determine M 3 C's harmonic circulation.

[0082] In a preferred embodiment, M is constructed by the following method: 3 C harmonic circulation simplified model:

[0083] Step S2.1: Get M 3 The circuit topology of C;

[0084] Specifically, M. 3 The circuit topology diagram of C is as follows Figure 2 As shown,

[0085] Step S2.2: Based on Kirchhoff's voltage law and the circuit topology, construct M 3 C basic mathematical model;

[0086] Step S2.3: Based on the two-dimensional sequence component algorithm, remove M 3 The high-order ripple components, harmonic components and bridge arm impedance voltage drop in the basic mathematical model of C generate M 3 C two-dimensional sequence component model;

[0087] It should be noted here that the two-dimensional sequence component method is briefly introduced below.

[0088] During normal operation, M 3 There are a series of steady-state capacitor voltage harmonics and bridge arm voltage / current harmonics in each bridge arm. 3Due to the symmetry of the C circuit topology, the frequency and amplitude of the same ripple or harmonic component in different bridge arms are equal, but the phase angle is different. Therefore, the phasor method can be used to use the phase shift of the same frequency and amplitude phasor relative to a common reference phasor (such as the phasor corresponding to the bridge arm au as the reference) to represent the distribution of ripple / harmonics in different bridge arms. The general expression of the M3C electrical quantity phasor matrix using the two-dimensional sequence component method is:

[0089]

[0090] in, is the two-dimensional sequence component of the electrical quantity phasor matrix with a frequency of ω; YX is the two-dimensional phase sequence, and the phase sequences Y and X can be positive sequence P, zero sequence Z, and negative sequence N; Sd and Sq are the d-axis and q-axis components of the AC electrical quantity respectively; A YX is a phase shift angle matrix, and the value of each element is -2π / 3, 0 or 2π / 3.

[0091] According to the definition of positive and negative zero sequence, nine two-dimensional phase shift angle matrices A YX The expression is:

[0092]

[0093] Based on the principle of multiplication and addition between phases, the operation rules of two-dimensional sequence components are as follows:

[0094] (1) Addition

[0095] Two-dimensional sequence with the same angular frequency and phase angle matrix Addition operations can be performed, and the result is the addition of the corresponding items of the d and q axis components:

[0096]

[0097] (2) Multiplication

[0098] The two-dimensional sequence component After multiplying by the constant a, the result is:

[0099]

[0100] (3) Phase Angle Shift

[0101]

[0102] (4) Angular velocity reversal

[0103] When the angular velocity is rotated in the opposite direction, that is, when the angular frequency is -ω, after changing the direction of rotation, the d-axis component remains unchanged, the q-axis component takes the opposite number, and the two-dimensional phase sequence is opposite to the original phase sequence:

[0104]

[0105] The operation rule of phase sequence inversion d is:

[0106] P=-N,N=-P,Z=-Z

[0107] (5) Differentiation

[0108] For the two-dimensional order component Differentiating it gives:

[0109]

[0110] (6) Phase multiplication

[0111] The two 2D sequence components Multiplying them gives:

[0112]

[0113] The addition operation rule between phase sequences is:

[0114] P+P=N,P+N=Z,P+Z=P

[0115] N+N=P,N+Z=Z,Z+Z=Z

[0116] Step S2.4: 3 C two-dimensional sequence component model to perform ripple coupling analysis and harmonic coupling analysis, and generate M 3 C ripple coupling model and M 3 C harmonic coupling model;

[0117] Step S2.5, generating a bridge arm voltage expression and a harmonic circulating current expression according to the ripple coupling model and the harmonic coupling model;

[0118] Step S2.6: Based on M 3 The power relationship and voltage characteristics of C in steady state are used to simplify the bridge arm voltage expression and generate the simplified bridge arm voltage expression; through the simplified bridge arm voltage expression, the harmonic circulating current expression is simplified to generate M 3 C Simplified model of harmonic circulating current.

[0119] In a preferred embodiment, the M 3 C harmonic circulation simplified model, including:

[0120]

[0121] Among them, i cir_BMS is the effective value of harmonic circulating current; ω S is the power frequency side frequency; n is the number of full-bridge submodules in the bridge arm; C is the submodule capacitance; v Cref is the submodule capacitor voltage reference value; K Pis the closed-loop proportional gain; ω is the system angular frequency; e d is the voltage effective value coefficient; L arm is the bridge arm inductance; x is the frequency ratio between the power frequency side and the divided frequency side; Q is the reactive power; P is the active power.

[0122] In an optional embodiment, based on Kirchhoff's voltage law, according to the circuit topology, M is constructed. 3 C basic mathematical model, including:

[0123] Based on Kirchhoff's voltage law and according to the circuit topology, a dynamic voltage balance equation, a bridge arm voltage equation and a submodule capacitor voltage dynamic equation are generated;

[0124] According to the dynamic voltage balance equation, bridge arm voltage equation and submodule capacitor voltage dynamic equation, M is constructed. 3 C basic mathematical model;

[0125] Among them, the dynamic voltage balance equation is specifically:

[0126]

[0127] In the formula, is the rate of change of the bridge arm current; I is the bridge arm current matrix; U S is the power frequency system voltage matrix; U L is the voltage matrix of the frequency division system; V is the bridge arm output voltage matrix; v N is the voltage difference between the neutral points of the two systems; B is the bridge arm distribution matrix;

[0128] The bridge arm voltage equation is specifically:

[0129] V=n·M*V c

[0130] Where, M is the bridge arm modulation signal matrix; V c is the submodule capacitance voltage matrix;

[0131] The submodule capacitor voltage dynamic equation is as follows:

[0132]

[0133] In the formula, is the rate of change matrix of the submodule capacitor voltage.

[0134] Specifically, the M 3 C two-dimensional sequence component model, including the two-dimensional sequence component expression of the modulation signal, the corresponding relationship between the phase sequence and the frequency, the definition of the variable order, the two-dimensional sequence component expression of the power frequency system voltage, the two-dimensional sequence component expression of the frequency division system voltage and the two-dimensional sequence component expression of the bridge arm current;

[0135] The two-dimensional sequence component expression of the modulated signal is specifically:

[0136]

[0137] in, is the two-dimensional sequence component of the modulation signal of the power frequency system; ω S is the power frequency angular frequency; PZ is the positive sequence-zero sequence component; is the two-dimensional sequence component of the modulation signal of the frequency division system; ω L is the frequency division angular frequency; ZP is the positive sequence-zero sequence component; It is the positive-sequence-zero-sequence component of the power frequency system modulation signal on the d-axis and q-axis; It is the zero-sequence-positive-sequence component of the modulation signal of the frequency division system on the d-axis and q-axis; is the positive-zero sequence component of the power frequency system voltage on the d-axis and q-axis; is the zero-sequence-positive-sequence component of the divided-frequency system voltage on the d-axis and q-axis;

[0138] The corresponding relationship between the phase sequence and the frequency is specifically:

[0139]

[0140] Among them, Y is the phase sequence variable in the vertical direction; X is the phase sequence variable in the horizontal direction; k Y(X) is the frequency coefficient; P is the positive sequence component; N is the negative sequence component; Z is the zero sequence component;

[0141] The definition of the variable order is specifically:

[0142] Order=|k X |+|k Y |

[0143] Among them, Order is the order of the variable; k X is the frequency coefficient of the frequency division system; k Y is the frequency coefficient of the power frequency system;

[0144] The two-dimensional sequence component expression of the power frequency system voltage is specifically:

[0145]

[0146] in, It is the two-dimensional sequence component representation of the power frequency system voltage;

[0147] The two-dimensional sequence component expression of the frequency division system voltage is specifically:

[0148]

[0149] in, is the two-dimensional sequence component representation of the voltage of the frequency division system;

[0150] The two-dimensional sequence component expression of the bridge arm current is specifically:

[0151]

[0152] in, It is the two-dimensional sequence component representation of the power frequency system current; It is the two-dimensional sequence component representation of the frequency division system current; are the d-axis and q-axis components of the power frequency system current in the rotating coordinate system; are the d-axis and q-axis components of the frequency division system current in the rotating coordinate system.

[0153] It should be noted here that the two-dimensional sequence component expression of the submodule capacitor voltage can be obtained according to the above submodule capacitor voltage dynamic equation through the two-dimensional sequence component expression of the bridge arm current and the two-dimensional sequence component expression of the modulation signal. The two-dimensional sequence component expression of the bridge arm voltage can be obtained according to the above bridge arm voltage equation through the two-dimensional sequence component expression of the submodule capacitor voltage and the two-dimensional sequence component expression of the modulation signal.

[0154] Preferably, the M 3 C two-dimensional sequence component model, including the two-dimensional sequence component expression of the modulation signal, the corresponding relationship between the phase sequence and the frequency, the definition of the variable order, the two-dimensional sequence component expression of the power frequency system voltage, the two-dimensional sequence component expression of the frequency division system voltage and the two-dimensional sequence component expression of the bridge arm current;

[0155] The two-dimensional sequence component expression of the modulated signal is specifically:

[0156]

[0157] in, is the two-dimensional sequence component of the modulation signal of the power frequency system; ω S is the power frequency angular frequency; PZ is the positive sequence-zero sequence component; is the two-dimensional sequence component of the modulation signal of the frequency division system; ω L is the frequency division angular frequency; ZP is the positive sequence-zero sequence component; It is the positive-sequence-zero-sequence component of the power frequency system modulation signal on the d-axis and q-axis; It is the zero-sequence-positive-sequence component of the modulation signal of the frequency division system on the d-axis and q-axis; is the positive-zero sequence component of the power frequency system voltage on the d-axis and q-axis; is the zero-sequence-positive-sequence component of the divided-frequency system voltage on the d-axis and q-axis;

[0158] The corresponding relationship between the phase sequence and the frequency is specifically:

[0159]

[0160] Among them, Y is the phase sequence variable in the vertical direction; X is the phase sequence variable in the horizontal direction; k Y(X) is the frequency coefficient; P is the positive sequence component; N is the negative sequence component; Z is the zero sequence component;

[0161] The definition of the variable order is specifically:

[0162] Order=|k X |+|k Y |

[0163] Among them, Order is the order of the variable; k X is the frequency coefficient of the frequency division system; k Y is the frequency coefficient of the power frequency system;

[0164] The two-dimensional sequence component expression of the power frequency system voltage is specifically:

[0165]

[0166] in, It is the two-dimensional sequence component representation of the power frequency system voltage;

[0167] The two-dimensional sequence component expression of the frequency division system voltage is specifically:

[0168]

[0169] in, is the two-dimensional sequence component representation of the voltage of the frequency division system;

[0170] The two-dimensional sequence component expression of the bridge arm current is specifically:

[0171]

[0172] in, It is the two-dimensional sequence component representation of the power frequency system current; It is the two-dimensional sequence component representation of the frequency division system current; are the d-axis and q-axis components of the power frequency system current in the rotating coordinate system; are the d-axis and q-axis components of the frequency division system current in the rotating coordinate system.

[0173] In a preferred embodiment, the M 3 C ripple coupling model, including;

[0174]

[0175]

[0176] in, For the frequency (k Y +1)ω S +k X ω L The capacitor voltage ripple, the component under the serial number (Y+P)X; For the frequency k Y ω S +(k X +1)ω L The capacitor voltage ripple, the component under the serial number Y(X+P); For the frequency (k Y +1)ω S -k X ω L The capacitor voltage ripple, the component under the serial number (Y+P)X; For the frequency k Y ω S -(k X +1)ω L The capacitor voltage ripple, the component under the serial number Y (XP); For the frequency k Y ω S -k X ω L The current component of, the value under the serial number YX; For the frequency k Y ω S -k X ω L The current component of , the value under the serial number YX; Add(·) is the forward coupling operator; Sub(·) is the reverse coupling operator; is the forward coupling transformation term based on the positive-sequence-zero-sequence component of the power frequency modulation signal; is the forward coupling transformation term based on the zero-sequence-positive-sequence component of the frequency division modulation signal; is the reverse coupling transformation term based on the zero-sequence-positive-sequence component of the frequency division modulation signal;

[0177] It should be noted that Add(·) is a forward coupling operator, which is used to forwardly superimpose the power frequency and the frequency division sideband components to compensate for the orthogonal phase offset; Sub(·) is a reverse coupling operator, which is used to reversely offset the impedance voltage drop on the frequency division side and eliminate the phase error of the reverse coupling path; is a forward coupling transformation term based on the positive-sequence-zero-sequence component of the power frequency modulation signal, which is used to convert the modulation signal of the power frequency system (including the positive-sequence and zero-sequence components) into a coupling term driving the harmonic circulating current through the matrix operation of the forward coupling operator Add(·); is a forward coupling transformation term based on the zero-sequence-positive sequence component of the frequency division modulation signal, which is used to convert the modulation signal (including the zero-sequence and positive-sequence components) of the frequency division system into a coupling term for driving harmonic circulating current through the matrix operation of the forward coupling operator Add(·); is a reverse coupling transformation term based on the zero-sequence-positive-sequence component of the frequency division modulation signal, used to convert the zero-sequence-positive-sequence component of the modulation signal on the frequency division side into a coupling term for suppressing harmonic circulating current through a matrix operation of the reverse coupling operator Sub(·);

[0178] Optionally, the steady-state value of the capacitor voltage ripple component of each submodule is:

[0179]

[0180] The M 3 C harmonic coupling model, including:

[0181]

[0182] in, For the frequency k Y ω S +k X ω L The current component of , the value under the serial number (Y+P)X; For the frequency k Y ω S +(k X +1)ω L The current component of, the value under the serial number Y(X+P); For the frequency (k Y +1)ω S -k X ω L The current component of , the value under the serial number (Y+P)X; For the frequency k Y ω S -(k X +1)ω L The current component of, the value under the serial number Y(XP); At the frequency C(k Y ω S +k X ω L ) capacitor voltage ripple, the component under the serial number YX; At the frequency C(k Y ω S +k X ω L )’s capacitor voltage ripple, the component under serial number YX.

[0183] Alternatively, the dq components of the steady-state current harmonics can be expressed as:

[0184]

[0185] Among them, L eq is the loop reactance of the corresponding sequence network.

[0186] Preferably, the harmonic circulation expression includes:

[0187]

[0188] in, The frequency is ω 1 The effective value of the harmonic circulating current component; The frequency is ω 2 The effective value of the harmonic circulating current component; The frequency is ω 3 The effective value of the harmonic circulating current component; The frequency is ω 4 The effective value of the harmonic circulating current component.

[0189] Bridge arm voltage effective value υ ω_RMS The expression is:

[0190]

[0191] When the harmonic circulating current closed-loop proportional suppression strategy is adopted, the effective value of the harmonic circulating current of a frequency i ω_RMS for:

[0192]

[0193] Preferably, the bridge arm voltage expression is:

[0194]

[0195] Among them, V z To show the bridge arm voltage component that will excite harmonic circulating current, including Four components;

[0196] It should be noted here that since the influence of the 4th-order and higher-order harmonic / ripple components on the frequency-divided transmission system is very small and can be ignored, only the 3rd-order and lower harmonic / ripple components will be considered in the following. 3 The bridge arm voltage expression of C is as above, where only the circulating current components with phase sequences of NP, NN, PN, and PP are extracted.

[0197] Optional, M 3 When C is in steady state, the q-axis voltage is 0, that is, u Sq =u Lq= 0. At this time, the active and reactive power of the power frequency and frequency division system can be expressed as:

[0198]

[0199] Define the ratio of the angular frequency on the power frequency side to the angular frequency on the divided frequency side as ω S :ω L =x:1. The analysis shows that the maximum value of the harmonic circulating current appears at M 3 When the power frequency side and the frequency division side absorb or emit the same reactive power, u Sd =u Ld =u d , Q S =Q L =Q. In describing M 3 When the active power of C on the power frequency side and the split frequency side is taken into account, if the converter loss is ignored, the two are the same in size but opposite in direction, and either one can be selected. This article uses P to represent the active power on the power frequency side, and the active power on the split frequency side is -P.

[0200] The simplified expression of the bridge arm voltage is specifically:

[0201]

[0202]

[0203] Among them, b 1 =1 / (36nω S C sm (v Cref ) 2 ).

[0204] Considering that the frequency of the frequency-divided transmission demonstration project currently in operation is 20Hz, an approximate simplified expression of the harmonic circulating current under this frequency scenario is given. When the frequency-divided frequency is 20Hz, that is, ω S :ω L =5∶2, the bridge arm voltage is:

[0205]

[0206] The simplified expression of the harmonic circulating current effective value in this frequency scenario is i cir_RMS for:

[0207]

[0208] In one embodiment, in order to verify the accuracy of the proposed method and model, the present invention conducts a verification experiment according to the parameters shown in the following table:

[0209]

[0210]

[0211] Specifically, according to the above steps, the harmonic circulating current electromagnetic transient simulation model and the harmonic circulating current approximate simplified model are established respectively, and the output results of the two models are compared, such as Figure 4 As shown. Figure 4 It can be seen that the difference between the established harmonic circulating current approximate simplified model and the electromagnetic transient simulation model is very small, and the harmonic circulating current waveform can be accurately and effectively fitted, which verifies the accuracy of the established model and the correctness of the proposed modeling method.

[0212] Based on the above method embodiment, the present invention provides a corresponding device embodiment.

[0213] like Figure 5 As shown, an embodiment of the present invention provides a method based on M 3 A harmonic circulation determination device of a harmonic circulation simplified model C, comprising: a parameter acquisition module, a model construction module and a model derivation module;

[0214] The parameter acquisition module is used to obtain M 3 C parameters and grid side parameters; among them, M 3 The parameters of the C component include the number of full-bridge submodules, bridge arm inductance, submodule capacitance, submodule capacitance voltage reference value, and closed-loop proportional gain; the parameters on the grid side include the power frequency side frequency, the frequency division side frequency, the power frequency side voltage d-axis component, and the frequency division side voltage d-axis component;

[0215] The model building module is used to 3 The parameters of the C element and the parameters of the grid side are based on the preset M 3 C Simplified model of harmonic circulation, determine M 3 C's harmonic circulation;

[0216] The model derivation module is used to obtain M 3 C circuit topology; Based on Kirchhoff's voltage law, according to the circuit topology, construct M 3 C basic mathematical model; based on two-dimensional sequence component algorithm, eliminating M 3 The high-order ripple components, harmonic components and bridge arm impedance voltage drop in the basic mathematical model of C generate M 3 C two-dimensional sequence component model; for M 3 C two-dimensional sequence component model to perform ripple coupling analysis and harmonic coupling analysis, and generate M 3 C ripple coupling model and M 3 C harmonic coupling model; generating a bridge arm voltage expression and a harmonic circulating current expression according to the ripple coupling model and the harmonic coupling model; based on M 3The power relationship and voltage characteristics of C in steady state are used to simplify the bridge arm voltage expression and generate the simplified bridge arm voltage expression; through the simplified bridge arm voltage expression, the harmonic circulating current expression is simplified to generate M 3 C Simplified model of harmonic circulating current.

[0217] It should be noted that the embodiment of the device described above corresponds to the above-mentioned embodiment of the present invention, and it can implement any of the above-mentioned methods for determining harmonic circulation based on the simplified M3C harmonic circulation model of the present invention. In addition, the embodiments of the above-mentioned device are merely schematic, wherein the modules described as separate components may or may not be physically separated, and the components displayed as modules may or may not be physical units, that is, they may be located in one place, or they may be distributed on multiple network units. Some or all of the modules may be selected according to actual needs to achieve the purpose of the scheme of this embodiment. In addition, in the accompanying drawings of the embodiment of the device provided by the present invention, the connection relationship between the modules indicates that there is a communication connection between them, which can be specifically implemented as one or more communication buses or signal lines. A person of ordinary skill in the art can understand and implement it without paying any creative labor.

[0218] Based on the above method embodiment of the present invention, a corresponding electronic device embodiment is provided.

[0219] An embodiment of the present invention provides an electronic device, including a processor, a memory, and a computer program stored in the memory and configured to be executed by the processor, wherein when the processor executes the computer program, the harmonic circulating current determination method based on the M3C harmonic circulating current simplified model described in any one of the present invention is implemented, or, when the processor executes the computer program, the functions of each module in the above-mentioned device embodiments are implemented.

[0220] Exemplarily, the computer program may be divided into one or more modules, which are stored in the memory and executed by the processor to implement the present invention. The one or more modules may be a series of computer program instruction segments capable of implementing specific functions, which are used to describe the execution process of the computer program in the terminal device.

[0221] The terminal device may be a computing device such as a desktop computer, a notebook, a PDA, a cloud server, etc. The terminal device may include, but is not limited to, a processor and a memory.

[0222] The processor may be a central processing unit (CPU), other general-purpose processors, digital signal processors (DSP), application-specific integrated circuits (ASIC), field-programmable gate arrays (FPGA) or other programmable logic devices, discrete gate or transistor logic devices, discrete hardware components, etc. The general-purpose processor may be a microprocessor or any conventional processor, etc. The processor is the control center of the terminal device, and uses various interfaces and lines to connect various parts of the entire terminal device.

[0223] The memory can be used to store the computer program and / or module, and the processor realizes various functions of the terminal device by running or executing the computer program and / or module stored in the memory, and calling the data stored in the memory. The memory can mainly include a program storage area and a data storage area, wherein the program storage area can store an operating system, at least one application required for a function, etc.; the data storage area can store data created according to the use of the mobile phone, etc. In addition, the memory can include a high-speed random access memory, and can also include a non-volatile memory, such as a hard disk, a memory, a plug-in hard disk, a smart memory card (Smart Media Card, SMC), a secure digital (SecureDigital, SD) card, a flash card (Flash Card), at least one disk storage device, a flash memory device, or other volatile solid-state storage devices.

[0224] Based on the above method embodiment, the present invention provides a storage medium embodiment;

[0225] Another embodiment of the present invention provides a storage medium, which includes a stored computer program, wherein when the computer program is running, the device where the storage medium is located is controlled to execute any one of the above-mentioned harmonic circulating current determination methods based on the M3C harmonic circulating current simplified model of the present invention.

[0226] The storage medium is a computer-readable storage medium, and the computer program includes computer program code, which may be in source code form, object code form, executable file or some intermediate form, etc. The computer-readable medium may include: any entity or device capable of carrying the computer program code, recording medium, USB flash drive, mobile hard disk, magnetic disk, optical disk, computer memory, read-only memory (ROM), random access memory (RAM), electric carrier signal, telecommunication signal and software distribution medium, etc. It should be noted that the content contained in the computer-readable medium may be appropriately increased or decreased according to the requirements of legislation and patent practice in the jurisdiction. For example, in some jurisdictions, according to legislation and patent practice, computer-readable media do not include electric carrier signals and telecommunication signals.

[0227] In the description of this specification, the description with reference to the terms "one embodiment", "some embodiments", "example", "specific example" or "some examples" etc. means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present application. Moreover, the specific features, structures, materials or characteristics described may be combined in any one or more embodiments or examples in a suitable manner. In addition, those skilled in the art may combine and combine different embodiments or examples described in this specification and the features of different embodiments or examples, unless they are contradictory.

[0228] The above is a preferred embodiment of the present invention. It should be pointed out that a person skilled in the art can make several improvements and modifications without departing from the principle of the present invention. These improvements and modifications are also considered to be within the scope of protection of the present invention.

Claims

1. A method based on M 3 C. A method for determining harmonic circulating currents of a simplified harmonic circulating current model, characterized in that: include: Get M 3 C parameters and grid side parameters; among them, M 3 The parameters of the C component include the number of full-bridge submodules, bridge arm inductance, submodule capacitance, submodule capacitance voltage reference value, and closed-loop proportional gain; the parameters on the grid side include the power frequency side frequency, the frequency division side frequency, the power frequency side voltage d-axis component, and the frequency division side voltage d-axis component; According to M 3 The parameters of the C element and the parameters of the grid side are based on the preset M 3 C harmonic circulation simplified model, determine M 3 C's harmonic circulation; Among them, M is constructed by the following method 3 C harmonic circulation simplified model: Get M 3 The circuit topology of C; Based on Kirchhoff's voltage law, according to the circuit topology, M is constructed. 3 C basic mathematical model; Based on the two-dimensional sequence component algorithm, M is eliminated 3 The high-order ripple components, harmonic components and bridge arm impedance voltage drop in the basic mathematical model of C generate M 3 C two-dimensional sequence component model; To M 3 C two-dimensional sequence component model to perform ripple coupling analysis and harmonic coupling analysis, and generate M 3 C ripple coupling model and M 3 C harmonic coupling model; Generate a bridge arm voltage expression and a harmonic circulating current expression according to the ripple coupling model and the harmonic coupling model; Based on M 3 The power relationship and voltage characteristics of C in steady state are used to simplify the bridge arm voltage expression and generate the simplified bridge arm voltage expression; through the simplified bridge arm voltage expression, the harmonic circulating current expression is simplified to generate M 3 C Simplified model of harmonic circulating current.

2. The method based on M as claimed in claim 1 3 C. A method for determining harmonic circulating currents of a simplified harmonic circulating current model, characterized in that: The M 3 C harmonic circulation simplified model, including: Among them, i cir_RMS is the effective value of harmonic circulating current; ω s is the power frequency side frequency; n is the number of full-bridge submodules in the bridge arm; C is the submodule capacitance; v Cref is the submodule capacitor voltage reference value; K P is the closed-loop proportional gain; ω is the system angular frequency; e d is the voltage effective value coefficient; L arm is the bridge arm inductance; x is the frequency ratio between the power frequency side and the divided frequency side; Q is the reactive power; P is the active power.

3. The method based on M as claimed in claim 2 3 C. A method for determining harmonic circulating currents of a simplified harmonic circulating current model, characterized in that: Based on Kirchhoff's voltage law, according to the circuit topology, M is constructed. 3 C basic mathematical model, including: Based on Kirchhoff's voltage law and according to the circuit topology, a dynamic voltage balance equation, a bridge arm voltage equation and a submodule capacitor voltage dynamic equation are generated; According to the dynamic voltage balance equation, bridge arm voltage equation and submodule capacitor voltage dynamic equation, M is constructed. 3 C basic mathematical model; Among them, the dynamic voltage balance equation is specifically: In the formula, is the rate of change of the bridge arm current; I is the bridge arm current matrix; U S is the power frequency system voltage matrix; U L is the voltage matrix of the frequency division system; V is the bridge arm output voltage matrix; v N is the voltage difference between the neutral points of the two systems; B is the bridge arm distribution matrix; The bridge arm voltage equation is specifically: V=n·M*V c Where, M is the bridge arm modulation signal matrix; V c is the submodule capacitance voltage matrix; The submodule capacitor voltage dynamic equation is as follows: In the formula, is the rate of change matrix of the submodule capacitor voltage.

4. The method based on M as claimed in claim 3 3 C. A method for determining harmonic circulating currents of a simplified harmonic circulating current model, characterized in that: The M 3 C two-dimensional sequence component model, including the two-dimensional sequence component expression of the modulation signal, the corresponding relationship between the phase sequence and the frequency, the definition of the variable order, the two-dimensional sequence component expression of the power frequency system voltage, the two-dimensional sequence component expression of the frequency division system voltage and the two-dimensional sequence component expression of the bridge arm current; The two-dimensional sequence component expression of the modulated signal is specifically: in, is the two-dimensional sequence component of the modulation signal of the power frequency system; ω s is the power frequency angular frequency; PZ is the positive sequence-zero sequence component; is the two-dimensional sequence component of the modulation signal of the frequency division system; ω L is the frequency division angular frequency; ZP is the positive sequence-zero sequence component; It is the positive-sequence-zero-sequence component of the power frequency system modulation signal on the d-axis and q-axis; It is the zero-sequence-positive-sequence component of the modulation signal of the frequency division system on the d-axis and q-axis; is the positive-zero sequence component of the power frequency system voltage on the d-axis and q-axis; is the zero-sequence-positive-sequence component of the divided-frequency system voltage on the d-axis and q-axis; The corresponding relationship between the phase sequence and the frequency is specifically: Among them, Y is the phase sequence variable in the vertical direction; X is the phase sequence variable in the horizontal direction; k Y(X) is the frequency coefficient; P is the positive sequence component; N is the negative sequence component; Z is the zero sequence component; The definition of the variable order is specifically: Order=|k X |+|k Y | Among them, Order is the order of the variable; k X is the frequency coefficient of the frequency division system; k Y is the frequency coefficient of the power frequency system; The two-dimensional sequence component expression of the power frequency system voltage is specifically: in, It is the two-dimensional sequence component representation of the power frequency system voltage; The two-dimensional sequence component expression of the frequency division system voltage is specifically: in, is the two-dimensional sequence component representation of the voltage of the frequency division system; The two-dimensional sequence component expression of the bridge arm current is specifically: in, It is the two-dimensional sequence component representation of the power frequency system current; It is the two-dimensional sequence component representation of the frequency division system current; are the d-axis and q-axis components of the power frequency system current in the rotating coordinate system; are the d-axis and q-axis components of the frequency division system current in the rotating coordinate system.

5. The method based on M as claimed in claim 4 3 C. A method for determining harmonic circulating currents of a simplified harmonic circulating current model, characterized in that: The M 3 C ripple coupling model, including; in, For the frequency (k Y +1)ω s +k X ω L The capacitor voltage ripple, the component under the serial number (Y+P)X; For the frequency k Y ω S +(k X +1)ω L The capacitor voltage ripple, the component under the serial number Y(X+P); For the frequency (k Y +1)ω S -k X ω L The capacitor voltage ripple, the component under the serial number (Y+P)X; For the frequency k Y ω S -(k X +1)ω L The capacitor voltage ripple, the component under the serial number Y (XP); For the frequency k Y ω S +k X ω L The current component of, the value under the serial number YX; For the frequency k Y ω S -k X ω L The current component of , the value under the serial number YX; Add(·) is the forward coupling operator; Sub(·) is the reverse coupling operator; is the forward coupling transformation term based on the positive-sequence-zero-sequence component of the power frequency modulation signal; is the forward coupling transformation term based on the zero-sequence-positive-sequence component of the frequency division modulation signal; is the reverse coupling transformation term based on the zero-sequence-positive-sequence component of the frequency division modulation signal; The M 3 C harmonic coupling model, including: in, For the frequency k Y ω S +k X ω L The current component of , the value under the serial number (Y+P)X; For the frequency k Y ω S +(k X +1)ω L The current component of, the value under the serial number Y(X+P); For the frequency (k Y +1)ω S -k X ω L The current component of , the value under the serial number (Y+P)X; For the frequency k Y ω S -(k X +1)ω L The current component of, the value under the serial number Y(XP); At the frequency C(k Y ω S +k X ω L ) capacitor voltage ripple, the component under the serial number YX; At the frequency C(k Y ω S -k X ω L )’s capacitor voltage ripple, the component under serial number YX.

6. The method based on M as claimed in claim 5 3 C. A method for determining harmonic circulating currents of a simplified harmonic circulating current model, characterized in that: The bridge arm voltage expression includes: Among them, V z is the bridge arm voltage component; The frequency is 2ω S +ω L , the voltage component of the bridge arm with phase sequence NP; The frequency is 2ω S -ω L , the bridge arm voltage component with phase sequence NN; The frequency is ω S +2ω L , the bridge arm voltage component with phase sequence PN; The frequency is ω S -2ω L , the bridge arm voltage component with phase sequence PP.

7. The method based on M as claimed in claim 6. 3 C. A method for determining harmonic circulating currents of a simplified harmonic circulating current model, characterized in that: The harmonic circulation expression includes: in, is the effective value of the harmonic circulating current component with frequency ω1; is the effective value of the harmonic circulating current component with frequency ω2; is the effective value of the harmonic circulating current component with a frequency of ω3; is the effective value of the harmonic circulating current component with a frequency of ω4.

8. A method based on M 3 C. A harmonic circulating current determining device of a simplified harmonic circulating current model, characterized in that: include: Parameter acquisition module, model building module and model derivation module; The parameter acquisition module is used to obtain M 3 C parameters and grid side parameters; among them, M 3 The parameters of the C component include the number of full-bridge submodules, bridge arm inductance, submodule capacitance, submodule capacitance voltage reference value, and closed-loop proportional gain; the parameters on the grid side include the power frequency side frequency, the frequency division side frequency, the power frequency side voltage d-axis component, and the frequency division side voltage d-axis component; The model building module is used to 3 The parameters of the C element and the parameters of the grid side are based on the preset M 3 C harmonic circulation simplified model, determine M 3 C's harmonic circulation; The model derivation module is used to obtain M 3 C circuit topology; Based on Kirchhoff's voltage law, according to the circuit topology, construct M 3 C basic mathematical model; based on two-dimensional sequence component algorithm, eliminating M 3 The high-order ripple components, harmonic components and bridge arm impedance voltage drop in the basic mathematical model of C generate M 3 C two-dimensional sequence component model; for M 3 C two-dimensional sequence component model to perform ripple coupling analysis and harmonic coupling analysis, and generate M 3 C ripple coupling model and M 3 C harmonic coupling model; generating a bridge arm voltage expression and a harmonic circulating current expression according to the ripple coupling model and the harmonic coupling model; based on M 3 The power relationship and voltage characteristics of C in steady state are used to simplify the bridge arm voltage expression and generate the simplified bridge arm voltage expression; through the simplified bridge arm voltage expression, the harmonic circulating current expression is simplified to generate M 3 C Simplified model of harmonic circulating current.

9. An electronic device, characterized in that: The method comprises a memory, a processor, and a computer program stored in the memory and executable on the processor; when the processor executes the computer program, the method can realize the M-based method according to any one of claims 1 to 7. 3 C. Method for determining harmonic circulating current of simplified harmonic circulating current model.

10. A storage medium having a computer program stored thereon, characterized in that: When the computer program is executed by a processor, the M-based 3 C. Method for determining harmonic circulating current of simplified harmonic circulating current model.

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