Method for locating dominant factors of hybrid DC impedance characteristics of diode rectification and MMC and related devices

Abstract

The present invention belongs to the field of high-voltage direct current transmission impedance modeling and stability analysis, and discloses a method for locating the dominant factors of a diode rectifier and MMC hybrid direct current impedance characteristic and a related device; the method comprises: establishing a diode rectifier and MMC hybrid direct current and alternating current port impedance analytical model; at the sending end alternating current PCC superimposed frequency f of the diode rectifier and MMC hybrid direct current and alternating current port impedance analytical model; p The positive sequence voltage disturbance #imgabs0# determines the dominant influencing factors of the impedance of the diode rectifier and MMC hybrid DC-AC port in different frequency bands; determines the main influencing frequency band of parameter changes on the impedance of the diode rectifier and MMC hybrid DC-AC port; determines the main influencing frequency band of parameter changes on the negative damping of the diode rectifier and MMC hybrid DC-AC port. The present invention provides key technical support for the oscillation risk screening, positioning and stability improvement of the new energy hybrid DC transmission system through diode rectification and MMC.

Description

Technical Field

[0001] The present invention belongs to the field of high-voltage direct current transmission impedance modeling and stability analysis, and in particular relates to a method for locating dominant factors of a diode rectifier and MMC hybrid direct current impedance characteristic and a related device. Background Art

[0002] At present, the development of new energy is advancing towards deserts, Gobi, wastelands and deep sea areas. The transmission of new energy via high-voltage direct current has become the dominant form of new energy base and large-scale development. The hybrid direct current transmission solution based on the parallel connection of large-capacity diode rectifiers and small-capacity modular multilevel converters (MMC) has low loss, low cost, small size and weight, high reliability, and can build voltage and frequency for passive systems. It has broad application prospects in large-scale new energy development and transmission.

[0003] The system oscillation problem caused by the interaction between the control of power electronic devices used in renewable energy power generation and DC transmission is becoming increasingly prominent. In recent years, many renewable energy projects have experienced multiple oscillation accidents, which seriously affect the safe and stable operation of the system. The diode rectifier and MMC hybrid DC transmission system also uses power electronic devices. The renewable energy system through diode rectifier and MMC hybrid DC transmission is a 100% power electronic power system, and the oscillation risk is particularly prominent, which restricts the development and engineering application of diode rectifier and MMC hybrid DC technology.

[0004] The analysis of impedance characteristics of diode rectification and MMC hybrid DC / AC ports and the location of dominant factors are the key to revealing system oscillation risks and formulating suppression strategies. Existing impedance characteristic analysis mainly analyzes the impedance characteristic variation law of two-level converters and modular multi-level converters by changing parameters. Existing impedance characteristic analysis methods have the following limitations:

[0005] The existing methods analyze the impedance characteristic changes of a single type of power electronic device, either wind power and photovoltaic based on two-level converters, or flexible DC and SVG based on MMC. However, diode rectifier and MMC hybrid DC are two types of power electronic devices, and there is dynamic coupling between them. The existing methods do not provide a hybrid device impedance characteristic analysis method composed of two types of power electronic devices, diode rectifier and MMC, and it is difficult to effectively explain the dominant influencing factors of impedance characteristics. Summary of the invention

[0006] The purpose of the present invention is to provide a method and related device for locating the dominant factors of the impedance characteristics of a diode rectifier and MMC hybrid DC, so as to solve the technical problem that the prior art cannot accurately locate the dominant factors of the impedance characteristics. The present invention adopts the impedance amplitude of the diode rectifier and MMC AC port, as well as the impedance amplitude sensitivity factor and the impedance phase sensitivity factor, to quantitatively analyze and locate the dominant influencing factors of the impedance characteristics of the diode rectifier and MMC hybrid DC in different frequency bands, and provides key technical support for the oscillation risk screening, positioning and stability improvement of the new energy through the diode rectifier and MMC hybrid DC transmission system.

[0007] In order to achieve the above object, the present invention adopts the following technical solution:

[0008] In a first aspect, the present invention provides a method for locating dominant factors of a hybrid DC impedance characteristic of a diode rectifier and MMC, comprising:

[0009] Establish the impedance analytical model of diode rectification and MMC hybrid DC / AC ports;

[0010] Based on the analytical model of diode rectification and MMC hybrid DC-AC port impedance, determine the magnitude of diode rectification and MMC AC port impedance; according to the magnitude of diode rectification and MMC AC port impedance, determine the dominant influencing factors of diode rectification and MMC hybrid DC-AC port impedance in different frequency bands;

[0011] Based on the impedance analytical model of the diode rectifier and MMC hybrid DC-AC port, the impedance amplitude sensitivity factor is determined; based on the impedance amplitude sensitivity factor, the main influencing frequency band of parameter changes on the impedance of the diode rectifier and MMC hybrid DC-AC port is determined;

[0012] Based on the impedance analytical model of the diode rectifier and MMC hybrid DC-AC port, the impedance phase sensitivity factor is determined; based on the impedance phase sensitivity factor, the main influencing frequency band of parameter changes on the negative damping of the diode rectifier and MMC hybrid DC-AC port is determined.

[0013] In a second aspect, the present invention provides a device for locating dominant factors of a hybrid DC impedance characteristic of a diode rectifier and MMC, comprising:

[0014] The modeling module is used to establish a diode rectifier and MMC hybrid DC-AC port impedance analytical model; and the sending-end AC PCC superimposed frequency f p Positive sequence voltage disturbance

[0015] The first positioning module is used to determine the impedance amplitude of the diode rectifier and the MMC AC port based on the diode rectifier and MMC hybrid DC AC port impedance analytical model; according to the impedance amplitude of the diode rectifier and the MMC AC port, determine the dominant influencing factors of the diode rectifier and the MMC hybrid DC AC port impedance in different frequency bands;

[0016] The second positioning module is used to determine the impedance amplitude sensitivity factor based on the impedance analytical model of the diode rectifier and MMC hybrid DC AC port; based on the impedance amplitude sensitivity factor, determine the main influencing frequency band of parameter changes on the impedance of the diode rectifier and MMC hybrid DC AC port;

[0017] The third positioning module is used to determine the impedance phase sensitivity factor based on the impedance analytical model of the diode rectifier and MMC hybrid DC AC port; based on the impedance phase sensitivity factor, determine the main influencing frequency band of parameter changes on the negative damping of the diode rectifier and MMC hybrid DC AC port.

[0018] In a third aspect, the present invention provides an electronic device, comprising a processor and a memory, wherein the processor is used to execute a computer program stored in the memory to implement the method for locating the dominant factors of the hybrid DC impedance characteristics of diode rectification and MMC.

[0019] In a fourth aspect, the present invention provides a computer-readable storage medium, wherein the computer-readable storage medium stores at least one instruction, and when the at least one instruction is executed by a processor, the method for locating the dominant factor of the hybrid DC impedance characteristic of the diode rectification and MMC is implemented.

[0020] Compared with the prior art, the present invention has the following unexpected beneficial effects:

[0021] The present invention provides a method for locating the dominant factors of the DC impedance characteristics of a diode rectifier and MMC hybrid, comprising: establishing a diode rectifier and MMC hybrid DC and AC port impedance analytical model; at the sending end AC PCC superimposed frequency f of the diode rectifier and MMC hybrid DC and AC port impedance analytical model; p Positive sequence voltage disturbance Based on the impedance analytical model of diode rectification and MMC hybrid DC AC port, the impedance amplitude of diode rectification and MMC AC port is determined; according to the impedance amplitude of diode rectification and MMC AC port, the dominant influencing factors of different frequency bands of diode rectification and MMC hybrid DC AC port impedance are determined; based on the impedance analytical model of diode rectification and MMC hybrid DC AC port, the impedance amplitude sensitivity factor is determined; based on the impedance amplitude sensitivity factor, the main influencing frequency band of parameter change on diode rectification and MMC hybrid DC AC port impedance is determined; based on the impedance phase sensitivity factor, the main influencing frequency band of parameter change on diode rectification and MMC hybrid DC AC port negative damping is determined. The present invention adopts the impedance amplitude of diode rectification and MMC AC port, the impedance amplitude sensitivity factor and the impedance phase sensitivity factor to quantitatively analyze and locate the dominant influencing factors of impedance characteristics of different frequency bands of diode rectification and MMC hybrid DC, and provides key technical support for oscillation risk screening, positioning and stability improvement of new energy through diode rectification and MMC hybrid DC transmission system.

[0022] Furthermore, the present invention aims at solving the problem of impedance characteristic analysis of various types of power electronic devices. Based on the impedance amplitude of diode rectification and MMC AC port, the present invention clarifies the dominant influencing factors of diode rectification and MMC hybrid DC-AC port impedance in different frequency bands, and effectively solves the problem of impedance characteristic analysis caused by the dynamic interaction of various types of power electronic devices.

[0023] Furthermore, in order to solve the problem of quantitative analysis of the dominant factors of impedance characteristics, the present invention proposes to use dual-dimensional quantitative indicators of impedance amplitude sensitivity factor and impedance phase sensitivity factor to effectively illustrate the main influencing frequency bands of each controller on the impedance characteristics of diode rectification and MMC hybrid DC-AC ports and negative damping.

[0024] Furthermore, the present invention can effectively quantify and analyze the dominant factors of the DC impedance characteristics of diode rectification and MMC hybrid, and provide key technical support for oscillation analysis and resolution of the DC transmission system of new energy through diode rectification and MMC hybrid, as well as system stability improvement. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] The accompanying drawings constituting a part of the present invention are used to provide a further understanding of the present invention. The exemplary embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute an improper limitation of the present invention. In the accompanying drawings:

[0026] Figure 1 It is a schematic diagram of the topological structure of the hybrid DC system of diode rectification and MMC;

[0027] Figure 2 This is the MMC control block diagram;

[0028] Figure 3 It is a flow chart of a method for locating dominant factors of a diode rectifier and MMC hybrid DC impedance characteristic of the present invention;

[0029] Figure 4 It is a schematic diagram of diode rectification and MMC hybrid DC-AC port impedance;

[0030] Figure 5 Schematic diagram of the effect of MMC AC voltage control on diode rectification and MMC hybrid DC-AC port impedance characteristics;

[0031] Figure 6 Schematic diagram of the effect of MMC AC current control on diode rectification and MMC hybrid DC / AC port impedance characteristics;

[0032] Figure 7 It is a structural block diagram of a device for locating dominant factors of a hybrid DC impedance characteristic of a diode rectifier and MMC according to the present invention;

[0033] Figure 8 The figure is a structural block diagram of an electronic device. DETAILED DESCRIPTION

[0034] The present invention will be described in detail below with reference to the accompanying drawings and in combination with embodiments. It should be noted that the embodiments and features in the embodiments of the present invention can be combined with each other without conflict.

[0035] The following detailed description is an exemplary description, which is intended to provide further detailed description of the present invention. Unless otherwise specified, all technical terms used in the present invention have the same meaning as those generally understood by those skilled in the art to which the present invention belongs. The terms used in the present invention are only for describing specific embodiments, and are not intended to limit the exemplary embodiments according to the present invention.

[0036] Example 1

[0037] The present invention proposes a method for locating dominant factors of a hybrid DC impedance characteristic of a diode rectifier and an MMC. The topological structure of a hybrid DC system of a diode rectifier and an MMC using the method comprises: an AC filter 1, a diode rectifier three-winding transformer 2, an MMC AC connection transformer 3, a diode rectifier 4, an MMC (Modular Multilevel Converter) 5, a diode rectifier smoothing reactor 6, an MMC smoothing reactor 7, a DC transmission line 8 and a receiving-end converter station 9.

[0038] The AC filter 1, the high-voltage side winding of the diode rectifier three-winding transformer 2, and the high-voltage side winding of the MMC AC connection transformer 3 are connected to the sending-end AC PCC. The two low-voltage side windings of the diode rectifier three-winding transformer 2 are connected to the AC side of the diode rectifier 4, and the diode rectifier 4 is composed of two groups of 6-pulse diode rectifier valve groups. The low-voltage side winding of the MMC AC connection transformer 3 is connected to the AC side of the MMC5, and the MMC5 is a small-capacity modular multilevel converter. The DC side of the diode rectifier 4 is connected via the diode rectifier smoothing reactor 6 (L oD ), and the DC side of MMC5 through MMC smoothing reactor 7 (L oM ), are connected to the DC transmission line 8 and then connected to the receiving end converter station 9. The receiving end converter station is equivalent to an ideal DC voltage source. abc is the three-phase voltage of the sending-end AC PCC, i abc is the three-phase AC current at the sending end, The diode rectifies the three-phase AC current. is the MMC AC three-phase current. is the diode rectified DC voltage, is the diode rectified DC current, is the MMC DC voltage, is the MMC DC current. is the DC voltage at the sending end, is the DC current at the sending end.

[0039] The present invention proposes a method for locating the dominant factors of a diode rectifier and MMC hybrid DC impedance characteristic, comprising the following steps:

[0040] Step 1, establish a diode rectification and MMC hybrid DC and AC port impedance analytical model;

[0041] After the diode rectifier and MMC hybrid DC system is running stably, the AC PCC superimposed frequency f p Positive sequence voltage disturbance The diode rectification and MMC hybrid DC / AC port impedance analytical model is obtained by solving steps 1.1 to 1.7; the frequency range of the positive sequence voltage disturbance is 1 to 1000 Hz, and the amplitude is the base frequency voltage V 1 After the disturbance is superimposed, the small signal is obtained by subtracting the steady-state signal from the signal after the disturbance is superimposed, and the amplitude of the small signal is within 10% of the steady-state signal. In the present invention, except for the steady-state signal clearly stated, all others are small signals;

[0042] In one embodiment, the frequency f p The value of is 1Hz~1000Hz;

[0043] Step 1.1, according to Figure 1The main circuit topology of the diode rectifier and MMC hybrid DC system is shown, and Figure 2 The MMC control block diagram is shown in the figure, and the diode rectifier AC port admittance matrix Y is established. DR for:

[0044] Y DR =[T DR +F dc1 (F i +F dc4 ) -1 F dc3 ] -1 ·[Y DR0 -F dc1 (F i +F dc4 ) -1 (F v -F dc2 )]+Y flt (1)

[0045] Where, T DR is the diode rectifier three-winding transformer leakage reactance influence matrix; F dc1 is the multi-harmonic interaction matrix of the first DC side; F dc2 is the multi-harmonic interaction matrix of the second DC side; F dc3 is the third DC side multi-harmonic interaction matrix; F dc4 is the fourth DC side multi-harmonic interaction matrix; F i Y is the MMC AC current and circulating current control influence matrix; DR0 Y is the AC port admittance matrix when the diode rectifier operates independently; flt is the AC filter admittance matrix, which is determined by the type of AC filter configured with diode rectification, including but not limited to single-tuned filter and double-tuned filter; the matrix analytical expressions of each variable are calculated by steps 1.4 to 1.7;

[0046] Step 1.2, establish the MMC AC port admittance matrix Y MMC for:

[0047]

[0048] In the formula, k MMC The ratio of the MMC AC connection transformer 3 is A. d is the MMC bridge arm current differential mode matrix; F v is the MMC AC voltage control influence matrix. The analytical expressions of each variable matrix are calculated from steps 1.4 to 1.7;

[0049] Step 1.3, according to the established diode rectifier AC port admittance matrix and MMC AC port admittance matrix, calculate and obtain the diode rectifier and MMC mixed DC AC port admittance matrix Y;

[0050] Y=Y DR +Y MMC (3)

[0051] Step 1.4: Establish the AC port admittance matrix Y when the diode rectifier operates independently DR0 , whose analytical expression is

[0052]

[0053] Among them, k DR The diode rectifier three-winding transformer has a transformation ratio of 2; S a is the steady-state voltage Toeplitz matrix of the diode rectifier a-phase switching function; D ad is the AC and DC voltage transformation matrix; Z LoD is the diode rectifier smoothing reactor impedance; is the steady-state voltage Toeplitz matrix of phase a of the high-voltage side winding of the diode rectifier three-winding transformer 2; is the Toeplitz matrix of the diode rectifier steady-state DC current; F DR is the (24g+3)×(24g+3) voltage normalization coefficient matrix, g is the sideband frequency considering the characteristic harmonics of diode rectification; C is the sub-diagonal coefficient matrix;

[0054] According to the double Fourier series expansion method, the steady-state voltage Toeplitz matrix S of the diode rectifier a-phase switching function is calculated. a , the order is (24g+3)×(24g+3), the analytical expression of the middle column is shown in formula (5), and the remaining columns are obtained according to the Toeplitz matrix principle;

[0055]

[0056] is the fundamental frequency voltage phase; is the steady-state voltage Toeplitz matrix of phase a of the high-voltage side winding of the diode rectifier three-winding transformer 2, with an order of (24g+3)×(24g+3). The analytical expression of the middle column is shown in formula (6), and the remaining columns are obtained according to the Toeplitz matrix principle;

[0057]

[0058] The superscript "*" indicates conjugation, and "T" indicates transposition. The voltage of phase a of the high-voltage side winding of the diode rectifier three-winding transformer 2 is at the base frequency f. 1 , 11 times 11f1 , 13 times 13f 1 The steady-state component of

[0059] is the Toeplitz matrix of the steady-state DC current of the diode rectification, with an order of (24g+3)×(24g+3). The analytical expression of the middle column is shown in equation (7), and the remaining columns are obtained according to the Toeplitz matrix principle;

[0060]

[0061] in, The diode rectifier DC current is at a frequency of 0Hz and 12 times the frequency of 12f. 1 The steady-state component of

[0062] C is the secondary diagonal coefficient matrix, expressed as

[0063]

[0064] F DR It is a (24g+3)×(24g+3) voltage normalization coefficient matrix, except for the following elements, all other elements are 0;

[0065]

[0066] V 1 is the fundamental frequency voltage amplitude; D ad is the AC and DC voltage transformation matrix, and the expression is:

[0067] D ad =3·diag[{1-|mod(k,3)|}| k＝-(12g+1)～12g+1 ] (10)

[0068] Where diag[·] represents a diagonal matrix operation, and mod(k,3) represents a modulo function with 3 as the divisor. Its expression is:

[0069]

[0070] Z LoD is the diode rectifier smoothing reactor impedance, and its analytical expression is:

[0071] Z LoD =j2πL oD ·diag[f p -(12g+1)f 1 ,…,f p -f 1 ,…,f p +(12g+1)f 1 ] (12)

[0072] Among them, f p is the disturbance frequency, L oD is a diode rectifier smoothing reactor; f 1 is the fundamental frequency;

[0073] Z dc is the impedance from the beginning to the end of the DC transmission line, and its analytical expression is:

[0074]

[0075] Among them, Z n Z is the impedance of the n-section π-type equivalent circuit viewed from the beginning to the end of the DC transmission line; 1 is the first term of the recursive formula, i.e., the impedance of a π-type equivalent circuit from the beginning to the end of the DC transmission line; the DC transmission line is equivalent to n π-type circuits, and the equivalent resistance of each π-type circuit is R dcL , the equivalent inductance is L dcL , the equivalent capacitance is C dcL , correspondingly, the impedance analytical expressions of the equivalent resistance, equivalent inductance, and equivalent capacitance of a single-section π-type circuit are:

[0076]

[0077] Where U is the (24g+3)×(24g+3) identity matrix;

[0078] Step 1.5: According to the MMC control block diagram, calculate the MMC AC current and circulating current control influence matrix F i , its analytical expression is:

[0079]

[0080] in, is the Toeplitz matrix of the upper bridge arm capacitor voltage of phase a of the MMC steady state, with an order of (24g+3)×(24g+3); is the Toeplitz matrix of the upper bridge arm modulation signal of the MMC steady-state a phase, with an order of (24g+3)×(24g+3); is the MMC bridge arm capacitance admittance matrix; is the Toeplitz matrix of the upper arm current of phase a of the MMC in steady state, with the order of (24g+3)×(24g+3); is the MMC AC current control coefficient matrix; kMMC The ratio of the MMC AC connection transformer 3 is A. d It is the MMC bridge arm current differential mode matrix; A is the MMC circulation control coefficient matrix; c It is the common mode matrix of the MMC bridge arm current; is the MMC bridge arm inductance impedance matrix; is the MMC AC voltage control coefficient matrix; It is the leakage reactance of MMC AC connecting transformer 3 converted to the high voltage side.

[0081] is the MMC AC current control coefficient matrix, and its calculation formula is:

[0082]

[0083] in, is the MMC AC current control decoupling coefficient; is the transfer function matrix of the AC current PI controller, and its expression is

[0084]

[0085] in, are the proportional coefficient and integral coefficient of the AC current PI controller respectively;

[0086] is the delay transfer function matrix of the MMC control link, and its expression is

[0087]

[0088] Among them, T s Control link delay for MMC;

[0089] G ad is the Park transform d-axis (24g+3)×(24g+3) coefficient matrix, except for the following elements, all other elements are 0, k=-(12g+1)~12g+1;

[0090]

[0091] G aq is the Park transform q-axis (24g+3)×(24g+3) coefficient matrix, except for the following elements, all other elements are 0;

[0092]

[0093] G da is the Park inverse transform d-axis (24g+3)×(24g+3) coefficient matrix, except for the following elements, all other elements are 0;

[0094]

[0095] G qa is the Park inverse transform q-axis (24g+3)×(24g+3) coefficient matrix, except for the following elements, all other elements are 0;

[0096]

[0097] is the MMC circulation control coefficient matrix, and its calculation formula is:

[0098]

[0099] in, is the decoupling coefficient of MMC circulation control. is the transfer function matrix of the circulating PI controller, and its expression is:

[0100]

[0101] in, They are the proportional coefficient and integral coefficient of the circulating PI controller respectively;

[0102] G 2ad is the negative-sequence double frequency Park transform d-axis (24g+3)×(24g+3) coefficient matrix, except for the following elements, all other elements are 0;

[0103]

[0104] G 2aq is the negative-sequence double frequency Park transform q-axis (24g+3)×(24g+3) coefficient matrix, except for the following elements, all other elements are 0;

[0105]

[0106] G 2da It is the negative-sequence double frequency Park inverse transform d-axis (24g+3)×(24g+3) coefficient matrix, except for the following elements, all other elements are 0;

[0107]

[0108] G 2qa It is the negative sequence double frequency Park inverse transform q axis (24g+3)×(24g+3) coefficient matrix, except for the following elements, all other elements are 0;

[0109]

[0110] is the MMC AC voltage control coefficient matrix, and its calculation formula is:

[0111]

[0112] in, is the transfer function matrix of the AC voltage PI controller, and its expression is

[0113]

[0114] in, are the proportional coefficient and integral coefficient of the AC voltage PI controller respectively;

[0115] A d is the MMC bridge arm current differential mode matrix, and its expression is

[0116] A d =diag[{1+(-1) k}| k＝-(12g+1)～(12g+1) ] (31)

[0117] A c is the MMC bridge arm current common mode matrix, and its expression is

[0118]

[0119] is the Toeplitz matrix of the upper arm current of phase a of the MMC in steady state, with an order of (24g+3)×(24g+3). The analytical expression of the middle column is shown in equation (33), and the remaining columns are obtained according to the Toeplitz matrix principle;

[0120]

[0121] in, is the upper arm current of phase a in the MMC steady state at frequency kf 1 The steady-state component of

[0122] is the Toeplitz matrix of the upper bridge arm capacitor voltage of phase a of the MMC steady state, with an order of (24g+3)×(24g+3). The analytical expression of the middle column is shown in formula (34), and the remaining columns are obtained according to the Toeplitz matrix principle;

[0123]

[0124] in, is the MMC steady-state a-phase upper bridge arm capacitor voltage at frequency kf 1 The steady-state component of

[0125] is the Toeplitz matrix of the MMC steady-state a-phase upper bridge arm modulation signal, with an order of (24g+3)×(24g+3). The analytical expression of the middle column is shown in equation (35), and the remaining columns are obtained according to the Toeplitz matrix principle;

[0126]

[0127] in, The modulation signal of the upper bridge arm of the MMC steady-state phase a is at the frequency kf 1 The steady-state component of

[0128] is the MMC bridge arm capacitance admittance matrix, and its expression is:

[0129]

[0130] in, is the MMC submodule capacitance, N S is the number of MMC bridge arm submodules;

[0131] is the MMC bridge arm inductance impedance matrix, and its expression is:

[0132]

[0133] in, is the MMC bridge arm resistance, is the MMC bridge arm inductance, U is the (24g+3)×(24g+3) unit matrix;

[0134] The MMC AC connection transformer 3 is converted to the high-voltage side leakage reactance, and its expression is:

[0135]

[0136] Among them, L TMMC The leakage inductance of the MMC AC connection transformer 3 converted to the high-voltage side;

[0137] Step 1.6, according to the MMC control block diagram, calculate the MMC AC voltage control influence matrix F v , its analytical expression is:

[0138]

[0139] Step 1.7, calculate the diode rectifier three-winding transformer leakage reactance influence matrix T DR , its analytical expression is:

[0140]

[0141] The diode rectifier three-winding transformer 2 is converted to the high-voltage side leakage reactance, and its analytical expression is:

[0142]

[0143] Among them, L TDRThe leakage inductance of the diode rectifier three-winding transformer 2 converted to the high-voltage side;

[0144] The first DC side multi-harmonic interaction matrix F is calculated dc1 , its analytical expression is:

[0145]

[0146] Among them, A c0 is the common mode zero sequence matrix of the MMC bridge arm current, and its expression is:

[0147]

[0148] The second DC side multi-harmonic interaction matrix F is calculated dc2 , its analytical expression is:

[0149]

[0150] The third DC side multi-harmonic interaction matrix F is calculated dc3 , its analytical expression is:

[0151]

[0152] The fourth DC side multi-harmonic interaction matrix F is calculated dc4 , its analytical expression is:

[0153]

[0154] In the formula, Z LoM is the impedance of the MMC smoothing reactor, and its analytical expression is:

[0155] Z LoM =j2πL oM ·diag[f p -(12g+1)f 1 ,…,f p -f 1 ,…,f p +(12g+1)f 1 ]

[0156] Among them, L oM It is MMC smoothing reactor;

[0157] Step 2, according to the magnitude of the diode rectification and the MMC AC port impedance amplitude, determine the dominant influencing factors of the diode rectification and the MMC hybrid DC AC port impedance in different frequency bands;

[0158] Step 2.1, based on the established diode rectifier AC port admittance matrix Y DR and the MMC AC port admittance matrix YMMC , respectively calculate the diode rectifier AC port impedance and MMC AC port impedance The analytical expression is:

[0159]

[0160] Step 2.2, for any frequency f p Under this condition, when the positive sequence impedance amplitude of the diode rectifier AC port and the positive sequence impedance amplitude of the MMC AC port satisfy the following relationship:

[0161] (a) When When the frequency f p The impedance of the lower diode rectifier and MMC hybrid DC-AC port is dominated by the impedance of the MMC AC port;

[0162] (b) When When the frequency f p The impedance of the lower diode rectifier and MMC hybrid DC-AC port is dominated by the impedance of the diode rectifier AC port;

[0163] (c) When When the frequency f p The impedance of the lower diode rectifier and MMC hybrid DC-AC port is determined by the diode rectifier and the MMC AC port impedance;

[0164] Step 2.3, let the disturbance frequency f p By traversing from 1Hz to 1000Hz with a step interval of 1Hz, the dominant influencing factors of the impedance of the diode rectification and MMC hybrid DC-AC ports in different frequency bands can be determined;

[0165] Step 3, based on the impedance amplitude sensitivity factor, determine the main influencing frequency band of parameter changes on the diode rectification and MMC hybrid DC-AC port impedance;

[0166] Step 3.1, based on the established diode rectification and MMC hybrid DC AC port admittance matrix Y, calculate its AC port impedance Z p , the analytical expression is:

[0167]

[0168] Step 3.2, for any frequency f p Under this condition, calculate the impedance amplitude sensitivity factor S Amp ;

[0169]

[0170] Among them, “||” means taking the amplitude or absolute value. p(x) indicates that the impedance of the diode rectifier and the MMC hybrid DC / AC port is related to a certain parameter x, and Δx is the change of parameter x;

[0171] When the impedance amplitude sensitivity factor S Amp When the following relationship is met:

[0172] (a) When S Amp ≥S 1 When the parameter x has an effect on f p The diode rectification and the impedance of the MMC hybrid DC-AC port have the main influence at the frequency;

[0173] (b) When S Amp 1 When the parameter x has an effect on f p There is no effect of diode rectification and MMC hybrid DC-AC port impedance at the frequency;

[0174] In one embodiment, the amplitude threshold S 1 Take it as 0.1;

[0175] Step 3.3, let the disturbance frequency f p By traversing from 1Hz to 1000Hz with a step interval of 1Hz, the main influencing frequency band of parameter x on the impedance of the diode rectification and MMC hybrid DC-AC port can be determined;

[0176] Step 3.4, according to steps 3.1 to 3.3, by changing the proportional coefficient of the MMC AC voltage PI controller Integration coefficient Proportional coefficient of AC current PI controller Integration coefficient Proportional coefficient of circulating current PI controller Integration coefficient The main frequency bands of influence of each controller on diode rectification and MMC hybrid DC / AC port impedance can be determined respectively. Among them, the union of the main frequency bands of influence of the proportional coefficient and integral coefficient of each controller is the main frequency band of influence of the controller;

[0177] Step 4, based on the impedance phase sensitivity factor, determine the main influencing frequency band of parameter changes on diode rectification and MMC hybrid DC-AC port negative damping;

[0178] Step 4.1, for any frequency f p Next, calculate the diode rectification and MMC hybrid DC-AC port impedance phase:

[0179]

[0180] ​Among them, "Im(·)" means taking the imaginary part of the impedance, "Re(·)" means taking the real part of the impedance, and "∠" means taking the phase of the impedance;

[0181] Calculating Impedance Phase Sensitivity Factor

[0182]

[0183] Step 4.2, when the impedance phase sensitivity factor S Pha When the following relationship is met:

[0184] (a) When S Pha ≥S 2 When the parameter x has an effect on f p The diode rectification and negative damping of the MMC hybrid DC-AC port have the main influence at the frequency;

[0185] (b) When S Pha 2 When the parameter x has an effect on f p The diode rectification has no effect on the negative damping of the MMC hybrid DC-AC port at this frequency.

[0186] In one embodiment, the amplitude threshold S 2 Take it as 0.05.

[0187] Step 4.3, let the disturbance frequency f p By traversing from 1Hz to 1000Hz with a step interval of 1Hz, the main influencing frequency band of parameter x on the negative damping of the diode rectification and MMC hybrid DC-AC port can be determined;

[0188] Step 4.4, according to steps 4.1 to 4.3, by changing the proportional coefficient of the MMC AC voltage PI controller Integration coefficient Proportional coefficient of AC current PI controller Integration coefficient Proportional coefficient of circulating current PI controller Integration coefficient MMC control link delay T s , the main influencing frequency bands of each controller and delay on the negative damping of the diode rectifier and MMC hybrid DC-AC port can be determined respectively; wherein, the union of the main influencing frequency bands of the proportional coefficient and integral coefficient of each controller is the main influencing frequency band of the controller; the process of applying the method for locating the dominant factors of the diode rectifier and MMC hybrid DC impedance characteristics is as follows Figure 3 shown.

[0189] In a specific implementation, the parameters of the diode rectification and MMC hybrid DC main circuit are shown in Table 1.

[0190] ​Table 1 Diode rectification and hybrid DC main circuit and control parameters

[0191]

[0192]

[0193] According to steps 1 to 3, calculate the diode rectifier (DR) AC port impedance in the frequency range of 1 to 1000Hz and MMC AC port impedance And the diode rectifier and MMC hybrid DC AC port impedance Z p , respectively Figure 4 In the sub-synchronous and super-synchronous frequency bands (within 100Hz), the impedance amplitudes of the DR and MMC AC ports are close and meet The impedance of the diode rectifier and MMC hybrid DC / AC port in this frequency band is determined by the impedance of the DR and MMC AC ports. In the mid-frequency band (about 100-300Hz), the DR AC port impedance amplitude is greater than the MMC AC port impedance amplitude, and meets In this frequency band, the impedance of the diode rectifier and MMC hybrid DC-AC port is dominated by the MMC AC port impedance. In the high frequency band (above 300Hz), the MMC AC port impedance amplitude is greater than the DR AC port impedance amplitude, and meets When , the impedance of the diode rectifier and MMC hybrid DC-AC port is dominated by the DR AC port impedance in this frequency band.

[0194] According to steps 1 to 3, the impedance Z of the diode rectifier and MMC hybrid DC / AC port in the frequency range of 1 to 1000 Hz is calculated. p , the MMC AC voltage PI controller proportional coefficient When the impedance increases from 1pu to 5pu, the impedance amplitude of the diode rectifier and MMC hybrid DC / AC port changes as shown in the figure. Figure 5 As shown in the above sub-figure, the calculated impedance amplitude sensitivity factor S Amp like Figure 5 As shown in the figure below, in the low and medium frequency bands (below 300Hz) except for the base frequency of 50Hz, S Amp ≥0.1, the proportional coefficient of the MMC AC voltage PI controller has a major impact on the diode rectification and the MMC hybrid DC-AC port impedance in this frequency band.

[0195] According to steps 1 to 4, the impedance phase ∠Z of the diode rectifier and the MMC hybrid DC-AC port in the frequency range of 1 to 1000 Hz is calculated. p , the MMC AC current PI controller proportional coefficient When the impedance increases from 1pu to 2pu, the phase change of diode rectification and MMC hybrid DC / AC port impedance is as follows: Figure 6 As shown in the above sub-figure, the calculated impedance phase sensitivity factor S Pha like Figure 6 As shown in the following figure, in the frequency bands of 200Hz~300Hz and 400Hz~600Hz, S Pha ≥0.05, the proportional coefficient of the MMC AC voltage PI controller has a major impact on the diode rectification and the negative damping of the MMC hybrid DC-AC port in this frequency band.

[0196] Example 2

[0197] See also Figure 7 As shown, this embodiment also provides a device for locating dominant factors of a diode rectifier and MMC hybrid DC impedance characteristic, including:

[0198] The modeling module is used to establish a diode rectifier and MMC hybrid DC-AC port impedance analytical model; and the sending-end AC PCC superimposed frequency f p Positive sequence voltage disturbance

[0199] The first positioning module is used to determine the impedance amplitude of the diode rectifier and the MMC AC port based on the diode rectifier and MMC hybrid DC AC port impedance analytical model; according to the impedance amplitude of the diode rectifier and the MMC AC port, determine the dominant influencing factors of the diode rectifier and the MMC hybrid DC AC port impedance in different frequency bands;

[0200] The second positioning module is used to determine the impedance amplitude sensitivity factor based on the impedance analytical model of the diode rectifier and MMC hybrid DC AC port; based on the impedance amplitude sensitivity factor, determine the main influencing frequency band of parameter changes on the impedance of the diode rectifier and MMC hybrid DC AC port;

[0201] The third positioning module is used to determine the impedance phase sensitivity factor based on the impedance analytical model of the diode rectifier and MMC hybrid DC AC port; based on the impedance phase sensitivity factor, determine the main influencing frequency band of parameter changes on the negative damping of the diode rectifier and MMC hybrid DC AC port.

[0202] In a specific implementation, the modeling module establishes an analytical model of the impedance of the diode rectifier and MMC hybrid DC and AC ports; after the diode rectifier and MMC hybrid DC system are in stable operation, the AC PCC superimposed frequency f at the sending end is p Positive sequence voltage disturbance

[0203] In one embodiment, the frequency fp The value is 1Hz~1000Hz.

[0204] In one embodiment, the modeling module is based on Figure 1 The main circuit topology of the diode rectifier and MMC hybrid DC system is shown, and Figure 2 The MMC control block diagram is shown in the figure, and the diode rectifier AC port admittance matrix Y is established. DR for:

[0205] Y DR =[T DR + F dc1 ( F i +F dc4 ) -1 F dc3 ] -1 ·[Y DR0 -F dc1 (F i +F dc4 ) -1 (F v -F dc2 )]+Y flt (1)

[0206] Where, T DR is the diode rectifier three-winding transformer leakage reactance influence matrix; F dc1 is the multi-harmonic interaction matrix of the first DC side; F dc2 is the multi-harmonic interaction matrix of the second DC side; F dc3 is the third DC side multi-harmonic interaction matrix; F dc4 is the fourth DC side multi-harmonic interaction matrix; F i Y is the MMC AC current and circulating current control influence matrix; DR0 Y is the AC port admittance matrix when the diode rectifier operates independently; flt is the AC filter admittance matrix, which is determined by the type of AC filter configured with diode rectification, including but not limited to a single-tuned filter and a double-tuned filter.

[0207] In a specific implementation: the first positioning module determines the dominant influencing factors of different frequency bands of the diode rectification and the MMC hybrid DC AC port impedance according to the magnitude of the diode rectification and the MMC AC port impedance amplitude;

[0208] The first positioning module is based on the established diode rectifier AC port admittance matrix Y DR and the MMC AC port admittance matrix Y MMC , respectively calculate the diode rectifier AC port impedance and MMC AC port impedance The analytical expression is:

[0209]

[0210] The first positioning module is for any frequency f p Under this condition, when the positive sequence impedance amplitude of the diode rectifier AC port and the positive sequence impedance amplitude of the MMC AC port satisfy the following relationship:

[0211] (a) When When the frequency f p The impedance of the lower diode rectifier and MMC hybrid DC-AC port is dominated by the impedance of the MMC AC port;

[0212] (b) When When the frequency f p The impedance of the lower diode rectifier and MMC hybrid DC-AC port is dominated by the impedance of the diode rectifier AC port;

[0213] (c) When When the frequency f p The impedance of the lower diode rectifier and MMC hybrid DC-AC port is determined by the diode rectifier and the MMC AC port impedance;

[0214] The first positioning module sets the disturbance frequency f p By traversing from 1Hz to 1000Hz with a step interval of 1Hz, the dominant influencing factors of the diode rectification and MMC hybrid DC-AC port impedance in different frequency bands can be determined.

[0215] In a specific implementation: the second positioning module determines the main influencing frequency band of parameter changes on the impedance of the diode rectifier and the MMC hybrid DC-AC port based on the impedance amplitude sensitivity factor;

[0216] The second positioning module calculates the AC port impedance Z based on the established diode rectification and MMC hybrid DC AC port admittance matrix Y p , the analytical expression is:

[0217]

[0218] The second positioning module is for any frequency f p Under this condition, calculate the impedance amplitude sensitivity factor S Amp ;

[0219]

[0220] Among them, “||” means taking the amplitude or absolute value. p (x) indicates that the impedance of the diode rectifier and the MMC hybrid DC / AC port is related to a certain parameter x, and Δx is the change of parameter x;

[0221] When the impedance amplitude sensitivity factor S Amp When the following relationship is met:

[0222] (a) When S Amp ≥S 1 When the parameter x has an effect on f p The diode rectification and the impedance of the MMC hybrid DC-AC port have the main influence at the frequency;

[0223] (b) When S Amp 1 When the parameter x has an effect on f p There is no effect of diode rectification and MMC hybrid DC-AC port impedance at the frequency;

[0224] In one embodiment, the amplitude threshold S 1 Take it as 0.1.

[0225] The second positioning module sets the disturbance frequency f p By traversing from 1Hz to 1000Hz with a step interval of 1Hz, the main influencing frequency band of parameter x on the impedance of the diode rectification and MMC hybrid DC-AC port can be determined;

[0226] The second positioning module changes the MMC AC voltage PI controller proportional coefficient Integration coefficient Proportional coefficient of AC current PI controller Integration coefficient Proportional coefficient of circulating current PI controller Integration coefficient The main frequency bands of influence of each controller on diode rectification and MMC hybrid DC / AC port impedance can be determined respectively. Among them, the union of the main frequency bands of influence of the proportional coefficient and integral coefficient of each controller is the main frequency band of influence of the controller;

[0227] In a specific implementation: the third positioning module determines the main influencing frequency band of parameter changes on diode rectification and MMC hybrid DC-AC port negative damping based on the impedance phase sensitivity factor;

[0228] The third positioning module is for any frequency f p Next, calculate the diode rectification and MMC hybrid DC-AC port impedance phase:

[0229]

[0230] Among them, "Im(·)" means taking the imaginary part of the impedance, "Re(·)" means taking the real part of the impedance, and "∠" means taking the phase of the impedance;

[0231] Calculating Impedance Phase Sensitivity Factor ​

[0232]

[0233] The third positioning module has an impedance phase sensitivity factor S Pha When the following relationship is met:

[0234] (a) When S Pha ≥S 2 When the parameter x has an effect on f p The diode rectification and negative damping of the MMC hybrid DC-AC port have the main influence at the frequency;

[0235] (b) When S Pha 2 When the parameter x has an effect on f p The diode rectification has no effect on the negative damping of the MMC hybrid DC-AC port at this frequency.

[0236] In one embodiment, the amplitude threshold S 2 Take it as 0.05.

[0237] The third positioning module sets the disturbance frequency f p By traversing from 1Hz to 1000Hz with a step interval of 1Hz, the main influencing frequency band of parameter x on the negative damping of the diode rectification and MMC hybrid DC-AC port can be determined;

[0238] The third positioning module changes the proportional coefficient of the MMC AC voltage PI controller Integration coefficient Proportional coefficient of AC current PI controller Integration coefficient Proportional coefficient of circulating current PI controller Integration coefficient MMC control link delay T s , the main influencing frequency bands of each controller and delay on the negative damping of the diode rectifier and MMC hybrid DC-AC port can be determined respectively. Among them, the union of the main influencing frequency bands of the proportional coefficient and integral coefficient of each controller is the main influencing frequency band of the controller; the process of applying the method for locating the dominant factors of the diode rectifier and MMC hybrid DC impedance characteristics is as follows Figure 3 shown.

[0239] Example 3

[0240] See also Figure 8 As shown, the present invention also provides an electronic device 100 for implementing a method for locating dominant factors of a hybrid DC impedance characteristic of diode rectification and MMC; the electronic device 100 includes a memory 101, at least one processor 102, a computer program 103 stored in the memory 101 and executable on the at least one processor 102, and at least one communication bus 104.​

[0241] The memory 101 can be used to store the computer program 103, and the processor 102 implements the steps of the method for locating the dominant factors of the hybrid DC impedance characteristics of diode rectification and MMC described in Example 1 by running or executing the computer program stored in the memory 101 and calling the data stored in the memory 101. The memory 101 can mainly include a program storage area and a data storage area, wherein the program storage area can store an operating system, an application required for at least one function (such as a sound playback function, an image playback function, etc.), etc.; the data storage area can store data (such as audio data) created according to the use of the electronic device 100, etc. In addition, the memory 101 can 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 (Secure Digital, SD) card, a flash card (Flash Card), at least one disk storage device, a flash memory device, or other non-volatile solid-state storage devices.

[0242] The at least one processor 102 may be a central processing unit (CPU), or 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 processor 102 may be a microprocessor or any conventional processor, etc. The processor 102 is the control center of the electronic device 100, and uses various interfaces and lines to connect various parts of the entire electronic device 100.

[0243] The memory 101 in the electronic device 100 stores a plurality of instructions to implement a method for locating dominant factors of a diode rectifier and MMC hybrid DC impedance characteristic, and the processor 102 can execute the plurality of instructions to implement:

[0244] Establish a diode rectifier and MMC hybrid DC-AC port impedance analytical model; at the sending end of the diode rectifier and MMC hybrid DC-AC port impedance analytical model, the AC PCC superposition frequency f p Positive sequence voltage disturbance

[0245] Based on the analytical model of diode rectification and MMC hybrid DC-AC port impedance, determine the magnitude of diode rectification and MMC AC port impedance; according to the magnitude of diode rectification and MMC AC port impedance, determine the dominant influencing factors of diode rectification and MMC hybrid DC-AC port impedance in different frequency bands;

[0246] Based on the impedance analytical model of the diode rectifier and MMC hybrid DC-AC port, the impedance amplitude sensitivity factor is determined; based on the impedance amplitude sensitivity factor, the main influencing frequency band of parameter changes on the impedance of the diode rectifier and MMC hybrid DC-AC port is determined;

[0247] Based on the impedance analytical model of the diode rectifier and MMC hybrid DC-AC port, the impedance phase sensitivity factor is determined; based on the impedance phase sensitivity factor, the main influencing frequency band of parameter changes on the negative damping of the diode rectifier and MMC hybrid DC-AC port is determined.

[0248] Example 4

[0249] If the module / unit integrated in the electronic device 100 is implemented in the form of a software functional unit and sold or used as an independent product, it can be stored in a computer-readable storage medium. Based on this understanding, the present invention implements all or part of the process in the above-mentioned embodiment method, and can also be completed by instructing the relevant hardware through a computer program. The computer program can be stored in a computer-readable storage medium, and the computer program can implement the steps of the above-mentioned method embodiments when executed by the processor. Among them, the computer program includes computer program code, and the computer program code can be in source code form, object code form, executable file or some intermediate form. The computer-readable medium may include: any entity or device that can carry the computer program code, recording medium, U disk, mobile hard disk, disk, optical disk, computer memory and read-only memory (ROM, Read-Only Memory).

[0250] Those skilled in the art will appreciate that embodiments of the present invention may be provided as methods, systems, or computer program products. Therefore, the present invention may take the form of a complete hardware embodiment, a complete software embodiment, or an embodiment combining software and hardware. Moreover, the present invention may take the form of a computer program product implemented on one or more computer-usable storage media (including but not limited to disk storage, CD-ROM, optical storage, etc.) containing computer-usable program code.

[0251] The present invention is described with reference to flowcharts and / or block diagrams of methods, devices (systems), and computer program products according to embodiments of the present invention. It should be understood that each process and / or block in the flowchart and / or block diagram, as well as the combination of processes and / or blocks in the flowchart and / or block diagram, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, a special-purpose computer, an embedded processor, or other programmable data processing device to produce a machine, so that the instructions executed by the processor of the computer or other programmable data processing device generate instructions for implementing the processes in the flowchart and / or block diagram. Figure 1 A process or multiple processes and / or boxes Figure 1 A device that provides the functions specified in a block or multiple blocks.

[0252] These computer program instructions may also be stored in a computer-readable memory capable of directing a computer or other programmable data processing device to operate in a specific manner, so that the instructions stored in the computer-readable memory produce an article of manufacture comprising an instruction device, which implements the process Figure 1 A process or multiple processes and / or boxes Figure 1 A function specified in one or more boxes.

[0253] These computer program instructions can also be loaded onto a computer or other programmable data processing device so that a series of operating steps are executed on the computer or other programmable device to produce a computer-implemented process, thereby providing instructions for implementing the process in the computer or other programmable device. Figure 1 A process or multiple processes and / or boxes Figure 1 The steps for the functions specified in one or more boxes.

[0254] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention rather than to limit it. Although the present invention has been described in detail with reference to the above embodiments, ordinary technicians in the relevant field should understand that the specific implementation methods of the present invention can still be modified or replaced by equivalents. Any modification or equivalent replacement that does not depart from the spirit and scope of the present invention should be covered within the scope of protection of the claims of the present invention.

Claims

1. A method for locating the dominant factors of the DC impedance characteristics of a diode rectifier and MMC hybrid, characterized in that: include: Establish the impedance analytical model of diode rectification and MMC hybrid DC / AC ports; Based on the analytical model of diode rectification and MMC hybrid DC-AC port impedance, determine the magnitude of diode rectification and MMC AC port impedance; according to the magnitude of diode rectification and MMC AC port impedance, determine the dominant influencing factors of diode rectification and MMC hybrid DC-AC port impedance in different frequency bands; Based on the diode rectification and MMC hybrid DC-AC port impedance analytical model, the impedance amplitude sensitivity factor is determined; Based on the impedance amplitude sensitivity factor, the main frequency band of parameter changes on the impedance of the diode rectifier and MMC hybrid DC-AC port is determined; Based on the impedance analytical model of the diode rectifier and MMC hybrid DC-AC port, the impedance phase sensitivity factor is determined; based on the impedance phase sensitivity factor, the main influencing frequency band of parameter changes on the negative damping of the diode rectifier and MMC hybrid DC-AC port is determined; The impedance amplitude sensitivity factor is determined based on the diode rectification and MMC hybrid DC-AC port impedance analytical model; Based on the impedance amplitude sensitivity factor, the steps of determining the main influencing frequency band of parameter changes on the impedance of the diode rectifier and the MMC hybrid DC-AC port include: Based on the diode rectification and MMC hybrid DC and AC port admittance matrix Y, the AC port impedance Z is calculated p , the analytical expression is: For any frequency f p Under this condition, calculate the impedance amplitude sensitivity factor S Amp ; g is the sideband frequency considering the characteristic harmonics of diode rectification; Among them, || means taking the amplitude or absolute value; Z p (x) indicates that the impedance of the diode rectifier and the MMC hybrid DC / AC port is related to the parameter x, and Δx is the change of the parameter x; When the impedance amplitude sensitivity factor S Amp When the following relationship is met: (a) When S Amp ≥S1, parameter x has an effect on f p The diode rectification and the impedance of the MMC hybrid DC-AC port have the main influence at the frequency; (b) When S Amp < When S1, the parameter x has no influence on the impedance of the diode rectifier and MMC hybrid DC-AC port at p the frequency; S1 is the preset first amplitude critical value; The step of determining the impedance amplitude sensitivity factor based on the impedance analytical model of the diode rectifier and MMC hybrid DC / AC port; and determining the main influencing frequency band of the parameter change on the impedance of the diode rectifier and MMC hybrid DC / AC port based on the impedance amplitude sensitivity factor, further includes: Let the disturbance frequency f p The frequency band of the main influence of parameter x on the impedance of the diode rectifier and the MMC hybrid DC / AC port is determined by traversing from 1 Hz to 1000 Hz with a step interval of 1 Hz; the main influence frequency band is the one that satisfies S Amp The set of all frequency points ≥S1; By changing the MMC AC voltage PI controller proportional coefficient Integration coefficient Proportional coefficient of AC current PI controller Integration coefficient Proportional coefficient of circulating current PI controller Integration coefficient Determine the main influencing frequency bands of each controller on diode rectification and MMC hybrid DC / AC port impedance respectively; among which, the union of the main influencing frequency bands of the proportional coefficient and integral coefficient of each PI controller is the main influencing frequency band of the corresponding PI controller; The steps of determining the impedance phase sensitivity factor based on the impedance analytical model of the diode rectifier and MMC hybrid DC / AC port; and determining the main influencing frequency band of the parameter change on the negative damping of the diode rectifier and MMC hybrid DC / AC port based on the impedance phase sensitivity factor specifically include: For any frequency f p Next, calculate the diode rectification and MMC hybrid DC-AC port impedance phase: Among them, Im(·) means taking the imaginary part of the impedance, Re(·) means taking the real part of the impedance, and ∠ means taking the phase of the impedance; Calculate the impedance phase sensitivity factor: When the impedance phase sensitivity factor S Pha When the following relationship is met: (a) When S Pha ≥S2, parameter x has an effect on f p The diode rectification and negative damping of the MMC hybrid DC-AC port have the main influence at the frequency; (b) When S Pha < S2, the parameter x has no influence on the negative damping of the diode rectifier and the MMC hybrid DC-AC port at p the frequency; S2 is a preset second amplitude critical value; The step of determining the impedance phase sensitivity factor based on the impedance analytical model of the diode rectifier and MMC hybrid DC / AC port; and determining the main influencing frequency band of the parameter change on the negative damping of the diode rectifier and MMC hybrid DC / AC port based on the impedance phase sensitivity factor, further includes: Let the disturbance frequency f p The frequency band of the main influence of parameter x on the negative damping of the diode rectifier and the MMC hybrid DC-AC port is determined by traversing from 1 Hz to 1000 Hz with a step interval of 1 Hz; the main influence frequency band is the one that satisfies S Pha The set of all frequency points ≥S2; By changing the MMC AC voltage PI controller proportional coefficient Integration coefficient Proportional coefficient of AC current PI controller Integration coefficient Proportional coefficient of circulating current PI controller Integration coefficient MMC control link delay T s , the main influencing frequency bands of each PI controller and delay on the diode rectification and the negative damping of the MMC hybrid DC-AC port can be determined respectively; among them, the union of the main influencing frequency bands of the proportional coefficient and integral coefficient of each PI controller is the main influencing frequency band of the corresponding PI controller.

2. The method for locating the dominant factors of the hybrid DC impedance characteristics of diode rectification and MMC according to claim 1 is characterized in that: The steps of determining the magnitude of the diode rectification and MMC AC port impedance based on the diode rectification and MMC hybrid DC AC port impedance analytical model; and determining the dominant influencing factors of the diode rectification and MMC hybrid DC AC port impedance in different frequency bands according to the magnitude of the diode rectification and MMC AC port impedance, specifically include: Based on the diode rectifier AC port admittance matrix Y DR and the MMC AC port admittance matrix Y MMC , respectively calculate the diode rectifier AC port impedance and MMC AC port impedance The analytical expression is: For any frequency f p Under this condition, when the positive sequence impedance amplitude of the diode rectifier AC port and the positive sequence impedance amplitude of the MMC AC port satisfy the following relationship: (a) When When the frequency f p The impedance of the lower diode rectifier and MMC hybrid DC-AC port is dominated by the impedance of the MMC AC port; (b) When When the frequency f p The impedance of the lower diode rectifier and MMC hybrid DC-AC port is dominated by the impedance of the diode rectifier AC port; (c) When When the frequency f p The impedance of the lower diode rectifier and MMC hybrid DC-AC port is determined by the diode rectifier and the MMC AC port impedance.

3. The method for locating the dominant factors of the diode rectification and MMC hybrid DC impedance characteristics according to claim 2 is characterized in that: The step of determining the magnitude of the diode rectification and MMC AC port impedance based on the diode rectification and MMC hybrid DC AC port impedance analytical model; and determining the dominant influencing factors of the diode rectification and MMC hybrid DC AC port impedance in different frequency bands according to the magnitude of the diode rectification and MMC AC port impedance, further includes: Let the disturbance frequency f p The dominant influencing factors of the impedance of the diode rectification and MMC hybrid DC-AC port in different frequency bands were determined by traversing from 1Hz to 1000Hz with a step interval of 1Hz.

4. A device for locating dominant factors of the DC impedance characteristics of a diode rectifier and MMC hybrid, characterized in that: include: Modeling module, used to establish the impedance analytical model of diode rectification and MMC hybrid DC and AC ports; The first positioning module is used to determine the impedance amplitude of the diode rectifier and the MMC AC port based on the diode rectifier and MMC hybrid DC AC port impedance analytical model; according to the impedance amplitude of the diode rectifier and the MMC AC port, determine the dominant influencing factors of the diode rectifier and the MMC hybrid DC AC port impedance in different frequency bands; The second positioning module is used to determine the impedance amplitude sensitivity factor based on the diode rectification and MMC hybrid DC and AC port impedance analysis model; Based on the impedance amplitude sensitivity factor, the main frequency band of parameter changes on the impedance of the diode rectifier and MMC hybrid DC-AC port is determined; The third positioning module is used to determine the impedance phase sensitivity factor based on the impedance analytical model of the diode rectifier and MMC hybrid DC AC port; based on the impedance phase sensitivity factor, determine the main influencing frequency band of parameter changes on the negative damping of the diode rectifier and MMC hybrid DC AC port; The impedance amplitude sensitivity factor is determined based on the diode rectification and MMC hybrid DC-AC port impedance analytical model; Based on the impedance amplitude sensitivity factor, the steps of determining the main influencing frequency band of parameter changes on the impedance of the diode rectifier and the MMC hybrid DC-AC port include: Based on the diode rectification and MMC hybrid DC and AC port admittance matrix Y, the AC port impedance Z is calculated p , the analytical expression is: For any frequency f p Under this condition, calculate the impedance amplitude sensitivity factor S Amp ; g is the sideband frequency considering the characteristic harmonics of diode rectification; Among them, || means taking the amplitude or absolute value; Z p (x) indicates that the impedance of the diode rectifier and the MMC hybrid DC / AC port is related to the parameter x, and Δx is the change of the parameter x; When the impedance amplitude sensitivity factor S Amp When the following relationship is met: (a) When S Amp ≥S1, parameter x has an effect on f p The diode rectification and the impedance of the MMC hybrid DC-AC port have the main influence at the frequency; (b) When S Amp < When S1, the parameter x has no influence on the impedance of the diode rectifier and MMC hybrid DC-AC port at p the frequency; S1 is the preset first amplitude critical value; The step of determining the impedance amplitude sensitivity factor based on the impedance analytical model of the diode rectifier and MMC hybrid DC / AC port; and determining the main influencing frequency band of the parameter change on the impedance of the diode rectifier and MMC hybrid DC / AC port based on the impedance amplitude sensitivity factor, further includes: Let the disturbance frequency f p The frequency band of the main influence of parameter x on the impedance of the diode rectifier and the MMC hybrid DC / AC port is determined by traversing from 1 Hz to 1000 Hz with a step interval of 1 Hz; the main influence frequency band is the one that satisfies S Amp The set of all frequency points ≥S1; By changing the MMC AC voltage PI controller proportional coefficient Integration coefficient Proportional coefficient of AC current PI controller Integration coefficient Proportional coefficient of circulating current PI controller Integration coefficient Determine the main influencing frequency bands of each controller on diode rectification and MMC hybrid DC / AC port impedance respectively; among which, the union of the main influencing frequency bands of the proportional coefficient and integral coefficient of each PI controller is the main influencing frequency band of the corresponding PI controller; The steps of determining the impedance phase sensitivity factor based on the impedance analytical model of the diode rectifier and MMC hybrid DC / AC port; and determining the main influencing frequency band of the parameter change on the negative damping of the diode rectifier and MMC hybrid DC / AC port based on the impedance phase sensitivity factor specifically include: For any frequency f p Next, calculate the diode rectification and MMC hybrid DC-AC port impedance phase: Among them, Im(·) means taking the imaginary part of the impedance, Re(·) means taking the real part of the impedance, and ∠ means taking the phase of the impedance; Calculate the impedance phase sensitivity factor: When the impedance phase sensitivity factor S Pha When the following relationship is met: (a) When S Pha ≥S2, parameter x has an effect on f p The diode rectification and negative damping of the MMC hybrid DC-AC port have the main influence at the frequency; (b) When S Pha < When S < S2, the parameter x has no influence on the negative damping of the diode rectifier and the MMC hybrid DC-AC port at p the frequency; S2 is a preset second amplitude critical value; The step of determining the impedance phase sensitivity factor based on the impedance analytical model of the diode rectifier and MMC hybrid DC / AC port; and determining the main influencing frequency band of the parameter change on the negative damping of the diode rectifier and MMC hybrid DC / AC port based on the impedance phase sensitivity factor, further includes: Let the disturbance frequency f p The frequency band of the main influence of parameter x on the negative damping of the diode rectifier and the MMC hybrid DC-AC port is determined by traversing from 1 Hz to 1000 Hz with a step interval of 1 Hz; the main influence frequency band is the one that satisfies S Pha The set of all frequency points ≥S2; By changing the MMC AC voltage PI controller proportional coefficient Integration coefficient Proportional coefficient of AC current PI controller Integration coefficient Proportional coefficient of circulating current PI controller Integration coefficient MMC control link delay T s , the main influencing frequency bands of each PI controller and delay on the diode rectification and the negative damping of the MMC hybrid DC-AC port can be determined respectively; among them, the union of the main influencing frequency bands of the proportional coefficient and integral coefficient of each PI controller is the main influencing frequency band of the corresponding PI controller.

5. An electronic device, characterized in that: It comprises a processor and a memory, wherein the processor is used to execute a computer program stored in the memory to implement the method for locating the dominant factor of the DC impedance characteristic of the diode rectification and MMC hybrid as claimed in any one of claims 1 to 3.

6. A computer-readable storage medium, characterized in that: The computer-readable storage medium stores at least one instruction, and when the at least one instruction is executed by the processor, the method for locating the dominant factor of the diode rectification and MMC hybrid DC impedance characteristics as described in any one of claims 1 to 3 is implemented.

Images