CN106487254A - A kind of MMC converter valve moving die system Parameters design based on criterion of similarity - Google Patents

Abstract

The present invention provides a kind of MMC converter valve moving die system Parameters design based on criterion of similarity, comprises the steps：1) MMC converter valve equivalent model is set up；2) determine MMC converter valve criterion of similarity；3) MMC converter valve moving die system parameter is designed.The technical scheme that the present invention is provided establishes MMC converter valve equivalent model based on switch function, on the basis of equivalent model, MMC converter valve criterion of similarity proposed based on similarity theory novelty, the blank of the area research is filled up, has been that moving die system electrical parameter calculation provides necessary theory support.

Description

A kind of MMC converter valve moving die system Parameters design based on criterion of similarity

Technical field

The present invention relates to a kind of Parameters design of MMC valve, and in particular to a kind of MMC converter valve based on criterion of similarity Moving die system Parameters design.

Background technology

Flexible direct current technology is HVDC Transmission Technology of new generation, is that new energy power generation grid-connection, large size city load are powered, isolated island is supplied Electricity, multiterminal element networking provide brand-new solution, wherein modularization multi-level converter flexible DC power transmission (Multi-level Modular Converter High Voltage Direct-Current, MMC-HVDC) development that represents flexible direct current technology becomes Gesture.With increasing for MMC-HVDC engineer applied, the research and development of MMC-HVDC dynamic model emulation technology and platform development become One of urgent problem.

As analogue simulation system is mainly the system model that sets up according to the principle of similitude, i.e., must ensure analogue system first Equivalence with prototype system.For specific MMC-HVDC analogue system, then must assure that moving die system parts selection, Topological structure, the control aspect such as relay protective scheme equivalent.And how to follow for MMC-HVDC analogue system both at home and abroad similar Principle there is no full and accurate elaboration to set up so that MMC-HVDC dynamic model Simulation System Platform is realized lacking necessary theoretical foundation.

Content of the invention

For solving above-mentioned deficiency of the prior art, it is an object of the invention to provide a kind of MMC converter valve based on criterion of similarity Moving die system Parameters design.

The purpose of the present invention is realized using following technical proposals：

The present invention provides a kind of MMC converter valve moving die system Parameters design based on criterion of similarity, the mould in methods described Block multilevel converter is made up of A, B, C three-phase, is often made up of upper and lower two brachium pontis of the structure identical that connects；Upper and lower two The exchange end of the midpoint link block multilevel converter of brachium pontis；

In upper and lower two brachium pontis, each brachium pontis includes 1 reactor and N number of structure identical submodule；The submodule of each brachium pontis After block cascade, one end is connected with the exchange end of modularization multi-level converter；Other end series electrical after the sub-module cascade of each brachium pontis It is connected with the reactor of another two-phase brachium pontis after anti-device, forms the both positive and negative polarity bus of the modularization multi-level converter DC terminal；

Each submodule includes upper and lower two all-controlling power electronics device IGBT；

Which thes improvement is that methods described comprises the steps：

1) MMC converter valve equivalent model is set up；

2) determine MMC converter valve criterion of similarity；

3) MMC converter valve moving die system parameter is designed.

Further, the step 1) in, Practical Project is emulated with low pressure physical analogue means, based on similarity theorem and opening Close function and MMC converter valve equivalent model is set up, the correspondence theorem is pointed out to refer to two similar systems will be with identical Criterion of similarity, i.e. two systems are similar, then which keeps the ratio of a fixation in whole dynamic process respectively to dependent variable and parameter Example, i.e. simulation ratio；

According to the operation principle of MMC converter valve submodule, the switching state of MMC submodule is simulated with switch function；

Wherein, S represents that switch function, T1 and T2 represent two all-controlling power electronics devices up and down of MMC submodule respectively IGBT, the electric current for flowing through submodule represented with switch function meet following relation：

Wherein, i_i1And i_i2Represent brachium pontis and lower bridge arm current in the i-th phase of MMC respectively；u_i1, u_i2Refer to every mutually upper and lower brachium pontis All submodule capacitor voltage sums；S_i1jRepresent the on off state of j-th submodule of brachium pontis in i phase, S_i2jRepresent brachium pontis under i phase The on off state of j-th submodule；N represents the submodule number of each brachium pontis, C₀Represent submodule electric capacity；

MMC converter valve upper and lower bridge arm symmetric design, then have：

L₁=L₂=L_s(2)

Wherein：L₁、L₂、L_sRepresent brachium pontis inductance of A, B, C three-phase per phase；

Upper and lower bridge arm applies Kirchhoff's second law respectively, respectively obtains the differential equation group of MMC：

Three facies unit symmetric designs of MMC converter valve, the DC current that each facies unit flows through are i_dc/3；Separately by upper and lower bridge arm Reactor is identical, therefore alternating current i_iDivide equally in upper and lower bridge arm, have：

Formula (4) is substituted into formula (3), and two formulas in formula (3) are subtracted each other：

Obtained by formula (1) again：

Formula (6) is substituted in formula (5) and is obtained：

X submodule is had to put into if some time engraves brachium pontis, then constant for ensureing DC voltage, lower brachium pontis should have n-x submodule to throw Enter, i.e.,

By on bring formula (5) into, obtain the MMC dynamic physical simulation system (low pressure physical analogue means) based on switch function Converter valve equivalent model：

Wherein：i_dcThe summation of the DC current flow through for three facies units；u_dcPhase voltage for facies unit；R_dFor D.C. resistance； i_iFor alternating current.

Further, the step 2) in, using integration analogue method, by step 1) Chinese style (6) is organized into dimensionless shape Formula, i.e. both members are while divided by 6R_di_dc?：

Defining alternating current-direct current side current-modulation ratio is：

Wherein：T represents time, I_iAnd I_dcRespectively MMC AC output line current peak and DC current；Assume alternating current Stream and DC current keep current-modulation ratio in each controlling cycle, then according to step 1) Chinese style (6) and (12) are by formula (11) Approximately write as：

The MMC dynamic physical simulation system variable parameter different with the two of Practical Project groups is listed which respectively as formula (11) Expression formula：

In upper two formula, subscript 1 represents Practical Project parameter, and subscript 2 represents moving die system parameter；By correspondence theorem, if two electricity The physical process on road is similar, then must there is proportionate relationship between each corresponding physical quantity；It is expressed as：L_S1=k_LL_S2； C₀₁=k_cC₀₂；u_dc1=k_uu_dc2；t₁=k_tt₂；i_dc1=k_ii_dc2；R_d1=k_RR_d2；

Thus, formula (10) is write as：

When on moving die system with Practical Project brachium pontis submodule put into number x identical when, if two circuits are similar, two circuitry processes by Same differential equation, i.e., must have：

Affinity constant is simulated than being limited by the constraint of formula (13)；

The derivation mode for obtaining the MMC converter valve criterion of similarity based on similarity theory is：

Wherein：k_L、k_c、k_u、k_t、k_i、k_RRepresent inductance, the electricity of MMC dynamic physical simulation system and Practical Project respectively Appearance, voltage, time, electric current, the proportionality coefficient of resistance, π₁Criterion of similarity for D.C. resistance；π₂Phase for brachium pontis reactor Like criterion；π₃Criterion of similarity for submodule electric capacity.

Further, the step 3) in, design MMC converter valve moving die system parameter includes：

1. Capacity Ratio and voltage ratio selection mode areDetermined so as to electric current ratio and reactance ratio therewith

2. wherein tietransformer voltage on valve side U_c, that is, calculate MMC converter valve outlet side phase voltage formula be：

3. according to criterion of similarity π₁Obtain D.C. resistance R_d2：

u_dc1/R_d1i_dc1=u_dc2/R_d2i_dc2

4. brachium pontis reactor L_S1With smoothing reactor parameter L_S2：

According to criterion of similarity π₂, in conjunction with etc. time constant principle, have under identical time scale：

L_S1/R_d1=L_S2/R_d2

5. submodule capacitance parameter：In order to ensure equivalence, will submodule capacitance select identical with Practical Project, and with basis Criterion of similarity π₃Result of calculation approximately equal；

Wherein：N_SAnd N_VRepresent Capacity Ratio and the voltage ratio of MMC dynamic physical simulation system and Practical Project, S respectively_simWith V_simRepresent rated capacity and the rated voltage of dynamic physical simulation system；S_Engineering、V_EngineeringRepresent rated capacity and the volume of Practical Project Determine voltage；N_IAnd N_ZRepresent electric current ratio and reactance ratio respectively；L_S1And L_S2Represent Practical Project and MMC converter valve dynamic model respectively The brachium pontis reactor of system and smoothing reactor；R_d1And R_d2Represent the straight of Practical Project and MMC converter valve moving die system respectively Leakage resistance.

The excellent effect that has of technical scheme that the present invention is provided is：

The MMC converter valve moving die system Parameters design based on criterion of similarity that the present invention is provided, is set up based on switch function MMC converter valve equivalent model, on the basis of equivalent model, proposes the MMC change of current based on similarity theory novelty Valve criterion of similarity, has filled up the blank of the area research, is that moving die system electrical parameter calculation provides necessary theory support.

Description of the drawings

Fig. 1 is the simplified diagram of the foundation similarity theorem that the present invention is provided；Wherein：A () and (a ') represents three-dimensional respectively Geometric similarity figure；B () and (b ') represents physics similar phenomena figure respectively；

Fig. 2 is the topological diagram of the MMC physical simulating device converter valve that the present invention is provided；Wherein (a) is MMC physical analogy The topological diagram of device converter valve, (b) are the topological diagram of MMC physical simulating device converter valve submodule；

Fig. 3 is the facies unit electrical equivalent diagram of the MMC converter valve topology that the present invention is provided；

Fig. 4 is the primary structure topological diagram of the low pressure physical analogue means that the present invention is provided；

Fig. 5 is the experimental rig of the employing principle of similarity design that the present invention is provided, controlling stream when testing for STATCOM Journey and oscillogram.

Specific embodiment

Specific embodiment to the present invention is described in further detail below in conjunction with the accompanying drawings.

The following description and drawings fully illustrate specific embodiments of the present invention, to enable those skilled in the art to put into practice it ?.Other embodiments can include structure, logic, electric, process and other changes.Embodiment only generation The possible change of table.Unless explicitly requested, otherwise individually component and function are optional, and the order for operating can change. The part of some embodiments and feature can be included in or replace part and the feature of other embodiments.The enforcement of the present invention The scope of scheme includes the gamut of claims, and all obtainable equivalent of claims.Herein, These embodiments of the present invention individually or generally can be represented with term " invention " that it is convenient that this is used for the purpose of, and If in fact disclosing the invention more than, the scope for being not meant to automatically limit the application is any single invention or invention Design.

The present invention provides a kind of MMC converter valve moving die system Parameters design based on criterion of similarity, comprises the steps：

1) method that MMC converter valve equivalent model is set up based on similarity theorem and switch function

For the function in the high-power MMC-HVDC of laboratory proofing (power is hundreds of megawatts, and voltage is hundreds of kV grades), Needs first have to emulate real system with low pressure physical analogue means (power is thousands of watts, and voltage is number kV grade), are This first has to the principle according to similarity theorem, calculates the parameter of low pressure physical analogue means.

Correspondence theorem is pointed out：Two similar systems must be with identical criterion of similarity.I.e. once two systems are similar, then Which should keep the ratio of a fixation in whole dynamic process respectively to dependent variable and parameter, i.e. simulation ratio.Geometric similarity and Shown in similar phenomena such as Fig. 1 (a) (a ') (b) (b ').Correspondence theorem also illustrate criterion of similarity between two similar systems Number and its expression formula of criterion.

The present invention is first from the constraints for meeting similarity theorem, it is ensured that MMC moving die system and former real system etc. Effect property, on this basis, starts with from MMC converter valve equivalent circuit and studies its criterion of similarity.The topology of MMC converter valve and its Shown in facies unit electrical equivalent such as Fig. 2 (a).Modularization multi-level converter is made up of A, B, C three-phase, per by connecting Upper and lower two brachium pontis of structure identical constitute；The exchange end of the midpoint link block multilevel converter of upper and lower two brachium pontis；

In upper and lower two brachium pontis, each brachium pontis includes 1 reactor and N number of structure identical submodule；The submodule of each brachium pontis After block cascade, one end is connected with the exchange end of modularization multi-level converter；Other end series electrical after the sub-module cascade of each brachium pontis It is connected with the reactor of another two-phase brachium pontis after anti-device, forms the both positive and negative polarity bus of the modularization multi-level converter DC terminal；

As shown in Fig. 2 (b), each submodule includes upper and lower two all-controlling power electronics device IGBT；

According to the operation principle of MMC submodule, the switching state of MMC submodule can be simulated with switch function.

Wherein, T1 and T2 represent the IGBT up and down of MMC submodule respectively, the electric current for flowing through submodule represented with switch function Following relation should be met：

Wherein, i_i1And i_i2Represent brachium pontis and lower bridge arm current in the i-th phase of MMC respectively；u_i1, u_i2Refer to every mutually upper and lower brachium pontis All submodule capacitor voltage sums；S_i1jRepresent the on off state of j-th submodule of brachium pontis in i phase, S_i2jRepresent brachium pontis under i phase The on off state of j-th submodule；N represents the submodule number of each brachium pontis, C₀Represent submodule electric capacity.

Consideration MMC converter valve upper and lower bridge arm symmetric design, then have

L₁=L₂=L_s(2)

Upper and lower bridge arm applies Kirchhoff's second law respectively, can obtain the differential equation group of MMC respectively：

Because three facies unit symmetric designs, the DC current that therefore each facies unit flows through is i_dc/3；Separately by upper and lower bridge arm reactance Device is identical, therefore alternating current (i_i) also divide equally in upper and lower bridge arm.So having：

Formula (4) is substituted into formula (3), vertical type is subtracted each other：

Can be obtained by formula (1) again：

Formula (6) is substituted in (5) and is obtained：

X submodule is had to put into if some time engraves brachium pontis, then constant for ensureing DC voltage, lower brachium pontis should have n-x submodule to throw Enter, i.e.,：

Bring formula (5) into, the MMC dynamic simulator system converter valve equivalent model based on switch function can be obtained：

2) derivation method based on the MMC converter valve criterion of similarity of similarity theory

Using integration analogue method, further will (6) be organized into zero dimension (dimensionless) form, i.e. both members simultaneously divided by 6R_di_dc?：

Defining alternating current-direct current side current-modulation ratio is

Wherein I_iAnd I_dcRespectively MMC AC output line current peak and DC current.Thus, it is supposed that alternating current and straight Stream electric current keeps this current-modulation ratio within certain period, then can approximately write formula (11) as according to formula (6) and (9)

Which is listed respectively can as the expression formula of formula (11) for the dynamic model variable parameter different with the two of Practical Project groups：

In upper two formula, subscript 1 represents Practical Project parameter, and subscript 2 represents moving die system parameter, similarly hereinafter.By correspondence theorem, if The physical process of two circuits is similar, then must there is certain proportion relation between each corresponding physical quantity.It is expressed as：

L_S1=k_LL_S2；C₀₁=k_cC₀₂；u_dc1=k_uu_dc2；t₁=k_tt₂；i_dc1=k_ii_dc2；R_d1=k_RR_d2.

Thus, formula (10) can be write as

When on moving die system with prototype system, brachium pontis submodule input number x is identical, if two circuits are similar, the two circuit mistakes Journey should be by same differential equation, i.e., must have：

It can be seen that, affinity constant is simulated than being limited by the constraint of formula (13), rather than is arbitrarily chosen.

Derivation method such that it is able to obtain the MMC converter valve criterion of similarity based on similarity theory is：

3) MMC converter valve moving die system parameter designing

According to the derivation result of above similarity principle, reasonable selection ac and dc systemses simulation ratio is MMC-HVDC moving die system The key factor of simulator, the result of calculating should also meet the constraint of circuit voltage current power proportionality.

Such that it is able to obtain the main equipment parameters method for designing of MMC converter valve moving die system.

1. Capacity Ratio and voltage ratio selection mode areDetermined so as to electric current ratio and reactance ratio therewith：

2. wherein connection becomes voltage on valve side U_c, i.e. MMC transverter outlet side phase voltage calculation method is：

3. D.C. resistance R_d2, according to criterion of similarity π₁D.C. resistance R is obtained_d2Computational methods.

u_dc1/R_d1i_dc1=u_dc2/R_d2i_dc2

4. brachium pontis reactor L_S1With smoothing reactor parameter L_S2.

According to criterion of similarity π₂, it is considered to etc. time constant principle, have under identical time scale：

L_S1/R_d1=L_S2/R_d2

5. submodule capacitance parameter：In order to ensure equivalence, will submodule capacitance select identical with Practical Project, and with according to phase Like criterion π₃Result of calculation is close to.

Embodiment

According to moving die system and the equivalence of former real system, and the criterion of similarity of above-mentioned MMC converter valve dynamic model design, and Consideration practical engineering experience, test request of valve control system etc., it is determined that the parameters of MMC moving die system, are shown in Table 1.

1 systematic parameter of table

2 moving die system nominal parameter of table

STATCOM test has been carried out on moving die system.By test waveform as can be seen that the moving die system that is built can reach To expected test effect, higher with the real system waveform goodness of fit.

Above example is only in order to illustrate technical scheme rather than a limitation, although reference above-described embodiment is to the present invention Be described in detail, those of ordinary skill in the art still the specific embodiment of the present invention can be modified or Person's equivalent, these are all applying for pending this without departing from any modification or the equivalent of spirit and scope of the invention Within bright claims.

Claims (4)

1. how electric a kind of MMC converter valve moving die system Parameters design based on criterion of similarity, the modularization in methods described be Flat transverter is made up of A, B, C three-phase, is often made up of upper and lower two brachium pontis of the structure identical that connects；In upper and lower two brachium pontis The exchange end of link block multilevel converter at point；

In upper and lower two brachium pontis, each brachium pontis includes 1 reactor and N number of structure identical submodule；The submodule of each brachium pontis After block cascade, one end is connected with the exchange end of modularization multi-level converter；Other end series electrical after the sub-module cascade of each brachium pontis It is connected with the reactor of another two-phase brachium pontis after anti-device, forms the both positive and negative polarity bus of the modularization multi-level converter DC terminal；

Each submodule includes upper and lower two all-controlling power electronics device IGBT；

Characterized in that, methods described comprises the steps：

1) MMC converter valve equivalent model is set up；

2) determine MMC converter valve criterion of similarity；

3) MMC converter valve moving die system parameter is designed.

2. Parameters design as claimed in claim 1, it is characterised in that the step 1) in, simulated with low pressure physical Device sets up MMC converter valve equivalent model based on similarity theorem and switch function emulating Practical Project, described similar fixed Reason points out to refer to that two similar systems are similar with identical criterion of similarity, i.e. two systems, then which is to dependent variable and ginseng Number keeps the ratio of a fixation in whole dynamic process respectively, i.e. simulation ratio；

According to the operation principle of MMC converter valve submodule, the switching state of MMC submodule is simulated with switch function；

Wherein, S represents that switch function, T1 and T2 represent two all-controlling power electronics devices up and down of MMC submodule respectively IGBT, the electric current for flowing through submodule represented with switch function meet following relation：

$\left\{\begin{array}{c}{i}_{i1}=\frac{C_0}{\underset{j=1}{\overset{n}{\mathrm{\Σ}}}{S}_{i1j}}\·\frac{{\mathrm{du}}_{i1}}{dt}\\ i_{i2}=\frac{C_0}{\underset{j=1}{\overset{n}{\Σ}}{S}_{i2j}}\·\frac{{\mathrm{du}}_{i2}}{dt}\end{array}\right.i=(a,b,c)---\left(1\right)$

Wherein, i_i1And i_i2Represent brachium pontis and lower bridge arm current in the i-th phase of MMC respectively；u_i1, u_i2Refer to every mutually upper and lower brachium pontis All submodule capacitor voltage sums；S_i1jRepresent the on off state of j-th submodule of brachium pontis in i phase, S_i2jRepresent brachium pontis under i phase The on off state of j-th submodule；N represents the submodule number of each brachium pontis, C₀Represent submodule electric capacity；

MMC converter valve upper and lower bridge arm symmetric design, then have：

L₁=L₂=L_s(2)

Wherein：L₁、L₂、L_sRepresent brachium pontis inductance of A, B, C three-phase per phase；

Upper and lower bridge arm applies Kirchhoff's second law respectively, respectively obtains the differential equation group of MMC：

$\left\{\begin{array}{c}\frac{1}{2}{u}_{dc}+R_d{i}_{dc}+L_S\frac{{\mathrm{di}}_{i1}}{dt}-u_{i1}=u_{vi}\\ -\frac{1}{2}{u}_{dc}-R_d{i}_{dc}-L_S\frac{{\mathrm{di}}_{i2}}{dt}+u_{i2}=u_{vi}\end{array}\right.---\left(3\right)$

Three facies unit symmetric designs of MMC converter valve, the DC current that each facies unit flows through are i_dc/3；Separately by upper and lower bridge arm Reactor is identical, therefore alternating current i_iDivide equally in upper and lower bridge arm, have：

$\begin{array}{cc}{i}_{i1}=\frac{1}{2}{i}_i+\frac{1}{3}{i}_{dc},& i_{i2}=\frac{1}{3}{i}_{dc}-\frac{1}{2}{i}_i\end{array}---\left(4\right)$

Formula (4) is substituted into formula (3), and two formulas in formula (3) are subtracted each other：

$\frac{{\mathrm{di}}_{dc}}{dt}=\frac{3}{2L_S}(u_{i1}+u_{i2})-\frac{3}{2L_S}{u}_{dc}-\frac{3R_d}{L_S}{i}_{dc}---\left(5\right)$

Obtained by formula (1) again：

$\left\{\begin{array}{c}{u}_{i1}=\∫\frac{i_{i1}\·\underset{j=1}{\overset{n}{\mathrm{\Σ}}}{S}_{i1j}}{C_0}dt\\ u_{i2}=\∫\frac{i_{i2}\·\underset{j=1}{\overset{n}{\mathrm{\Σ}}}{S}_{i2j}}{C_0}dt\end{array}\right.i=(a,b,c)---\left(6\right)$

Formula (6) is substituted in formula (5) and is obtained：

$\frac{{\mathrm{di}}_{dc}}{dt}=\frac{3}{2L_S}\[(\∫\frac{i_{i1}\·\underset{j=1}{\overset{n}{\mathrm{\Σ}}}{S}_{i1j}}{C_0}dt+\∫\frac{i_{i2}\·\underset{j=1}{\overset{n}{\mathrm{\Σ}}}{S}_{i2j}}{C_0}dt)-u_{dc}\]-\frac{3R_d}{L_S}{i}_{dc}---\left(7\right)$

X submodule is had to put into if some time engraves brachium pontis, then constant for ensureing DC voltage, lower brachium pontis should have n-x submodule to throw Enter, i.e.,

$\begin{array}{cc}\underset{j=1}{\overset{n}{\Σ}}{S}_{i1j}=x,& \underset{j=1}{\overset{n}{\Σ}}{S}_{i2j}=n-x\end{array}$

By on bring formula (5) into, obtain the MMC dynamic physical simulation system converter valve equivalent model based on switch function：

$2L_S\frac{{\mathrm{di}}_{dc}}{dt}=3\[(\∫\frac{x\·i_i+{\mathrm{ni}}_{i2}}{C_0}dt)-u_{dc}\]-6R_d{i}_{dc}---\left(8\right)$

Wherein：i_dcThe summation of the DC current flow through for three facies units；u_dcPhase voltage for facies unit；R_dFor D.C. resistance； i_iFor alternating current.

3. Parameters design as claimed in claim 1, it is characterised in that the step 2) in, using integration analogue method, By step 1) Chinese style (6) is organized into Dimensionless Form, i.e. both members while divided by 6R_di_dc?：

$\frac{1}{3}\frac{L_S}{{\mathrm{tR}}_d}=\frac{{\mathrm{ni}}_{i2}\·t}{2C_0{R}_d{i}_{dc}}+\[(\frac{x\·t\·i_i}{2C_0{R}_d{i}_{dc}}-u_{dc}/2R_d{i}_{dc}\]-1---\left(7\right)$

Defining alternating current-direct current side current-modulation ratio is：

$m=\frac{I_i/2}{I_{dc}/3}---\left(8\right)$

Wherein：T represents time, I_iAnd I_dcRespectively MMC AC output line current peak and DC current；Assume alternating current Stream and DC current keep current-modulation ratio in each controlling cycle, then approximately write formula (11) according to formula (6) and (9) Become：

$\frac{1}{3}\frac{L_S}{{\mathrm{tR}}_d}=\frac{(1+m)n\·t}{6C_0{R}_d}+\[(\frac{m\·x\·t}{3C_0{R}_d}-u_{dc}/2R_d{i}_{dc}\]-1---\left(9\right)$

The MMC dynamic physical simulation system variable parameter different with the two of Practical Project groups is listed which respectively as formula (11) Expression formula：

$\frac{1}{3}\frac{L_{S1}}{t_1{R}_{d1}}=\frac{(m+1)n\·t_1}{6C_{01}{R}_{d1}}+\[(\frac{m\·x\·t_1}{3C_{01}{R}_{d1}}-u_{dc1})/2R_{d1}{i}_{dc1}\]-1---\left(10\right)$

$\frac{1}{3}\frac{L_{S2}}{t_2{R}_{d2}}=\frac{(m+1)n\·t_2}{6C_{02}{R}_{d2}}+\[(\frac{m\·x\·t_2}{3C_{02}{R}_{d2}}-u_{dc2})/2R_{d2}{i}_{dc2}\]-1---\left(11\right)$

In upper two formula, subscript 1 represents Practical Project parameter, and subscript 2 represents moving die system parameter；By correspondence theorem, if two electricity The physical process on road is similar, then must there is proportionate relationship between each corresponding physical quantity；It is expressed as：L_S1=k_LL_S2； C₀₁=k_cC₀₂；u_dc1=k_uu_dc2；t₁=k_tt₂；i_dc1=k_ii_dc2；R_d1=k_RR_d2；

Thus, formula (10) is write as：

$\frac{k_L}{k_t{k}_R}\frac{L_{S2}}{3t_2{R}_{d2}}=\frac{k_t}{k_R{k}_c}\frac{(m+1)n\·t_2}{6C_{02}{R}_{d2}}+\[(\frac{k_t}{k_R{k}_c}\frac{m\·x\·t_2}{3C_{02}{R}_{d2}}-\frac{k_u}{k_i{k}_R}\frac{u_{dc2}}{2R_{d2}{i}_{dc2}}\]-1---\left(12\right)$

When on moving die system with Practical Project brachium pontis submodule put into number x identical when, if two circuits are similar, two circuitry processes by Same differential equation, i.e., must have：

$\begin{array}{ccc}\frac{k_u}{k_i{k}_R}=1,& \frac{k_L}{k_R{k}_t}=1,& \frac{k_t}{k_c{k}_R}=1\end{array}---\left(13\right)$

Affinity constant is simulated than being limited by the constraint of formula (13)；

The derivation mode for obtaining the MMC converter valve criterion of similarity based on similarity theory is：

$\begin{array}{ccc}{\mathrm{\π}}_1=\frac{u_{dc}}{R_d{i}_{dc}},& {\mathrm{\π}}_2=\frac{L_S}{R_{d}t},& {\mathrm{\π}}_3=\frac{t}{R_d{C}_0}=\frac{t}{{\mathrm{xR}}_d{C}_{01}}\end{array}---\left(14\right)$

Wherein：k_L、k_c、k_u、k_t、k_i、k_RRepresent inductance, the electricity of MMC dynamic physical simulation system and Practical Project respectively Appearance, voltage, time, electric current, the proportionality coefficient of resistance, π₁Criterion of similarity for D.C. resistance；π₂Phase for brachium pontis reactor Like criterion；π₃Criterion of similarity for submodule electric capacity.

4. Parameters design as claimed in claim 1, it is characterised in that the step 3) in, design the MMC change of current Valve actuation modular system parameter includes：

1. Capacity Ratio and voltage ratio selection mode areDetermined so as to electric current ratio and reactance ratio therewith $\begin{array}{cc}{N}_I=\frac{N_S}{N_V},& N_Z=\frac{N_V}{N_I}\end{array};$

2. wherein tietransformer voltage on valve side U_c, that is, calculate MMC converter valve outlet side phase voltage formula be： $U_c=m\sqrt{3}{U}_{dc}/\sqrt{2};$

3. according to criterion of similarity π₁Obtain D.C. resistance R_d2：

u_dc1/R_d1i_dc1=u_dc2/R_d2i_dc2

4. brachium pontis reactor L_S1With smoothing reactor parameter L_S2：

According to criterion of similarity π₂, in conjunction with etc. time constant principle, have under identical time scale：

L_S1/R_d1=L_S2/R_d2

5. submodule capacitance parameter：In order to ensure equivalence, will submodule capacitance select identical with Practical Project, and with basis Criterion of similarity π₃Result of calculation approximately equal；

Wherein：N_SAnd N_VRepresent Capacity Ratio and the voltage ratio of MMC dynamic physical simulation system and Practical Project, S respectively_simWith V_simRepresent rated capacity and the rated voltage of dynamic physical simulation system；S_Engineering、V_EngineeringRepresent rated capacity and the volume of Practical Project Determine voltage；N_IAnd N_ZRepresent electric current ratio and reactance ratio respectively；L_S1And L_S2Represent Practical Project and MMC converter valve dynamic model respectively The brachium pontis reactor of system and smoothing reactor；R_d1And R_d2Represent the straight of Practical Project and MMC converter valve moving die system respectively Leakage resistance.