CN107944082A

CN107944082A - A kind of single port submodule MMC electro-magnetic transient generalized equivalent modeling methods

Info

Publication number: CN107944082A
Application number: CN201711011870.9A
Authority: CN
Inventors: 许建中; 赵禹辰; 冯谟可; 赵成勇
Original assignee: North China Electric Power University
Current assignee: North China Electric Power University
Priority date: 2017-10-25
Filing date: 2017-10-25
Publication date: 2018-04-20

Abstract

The present invention designs a kind of single port submodule MMC electro-magnetic transient generalized equivalent modeling methods.The present invention core technology scheme be：1st, the equivalent circuit based on single port submodule, row write nodal voltage equation, and utilize quick nested derivation algorithm, equivalent cancellation internal node.The Norton equivalent expression formula of equivalent circuit is tried to achieve by equation conversion, so as to obtain its thevenin equivalent circuit；2nd, using submodule thevenin equivalent circuit, the equivalent model of whole transverter is tried to achieve, and the bridge arm current value of each bridge arm is asked for using electromagnetic transients program；3rd, after solution of the equivalent circuit by a step-length, by trying to achieve the anti-node voltage value for solving single port MMC bridge arm internal nodes of bridge arm current, whole submodule internal informations are updated.

Description

A kind of single port submodule MMC electro-magnetic transient generalized equivalent modeling methods

Technical field

The present invention relates to a kind of general single port submodule MMC electro-magnetic transient generalized equivalent modeling methods, belong to flexible straight Flow technical field of electric power transmission.

Background technology

Modularization multi-level converter (modular multilevel converter, MMC) Neutron module The number of (submodule, SM) is because engineering demand is just being continuously increased, and the submodule topology of various functions advanced configuration complexity Just continue to bring out, although existing MMC models can greatly improve simulation efficiency and ensure very high simulation accuracy, existing mould Type is all based on greatly half-bridge and full-bridge submodule is established, and versatility is poor.The present invention is formed for any single port submodule MMC, by Dai Weinan equivalent models with based on nested quick derivation algorithm at the same time, it is proposed that a kind of general electro-magnetic transient is equivalent Modeling method.The modeling method proposed is substantially that the information of submodule internal node is transferred to external node with eliminating Portion's node, so that the submodule promise after depression of order or thevenin equivalent circuit are obtained, in asking for equivalent circuit one step-length of progress After solution, the anti-internal information for solving the whole submodules of rapid renewal can be passed through.This method has been unified to wear the parameter of Vernam model Solution procedure, the MMC formed to the single port submodule of arbitrary structures have very strong versatility.

The content of the invention

The present invention provides a kind of single port submodule MMC electro-magnetic transient generalized equivalent modeling methods, which includes Following steps：

Step 1：The respective IGBT of the single bridge arm whole submodules of single port MMC and its anti-paralleled diode is logical with one respectively Disconnected state is replaced in the variable-conductance G that high and low resistance value switches.Use trapezoidal integration that submodule capacitance is discrete for one at the same time One historical current source of conductance parallel connection, obtains the equivalent circuit of each submodule of the single bridge arms of single port MMC.Arranged using equivalent circuit Nodal voltage equation is write, the thinking based on quick nested derivation algorithm eliminates internal node.Single port is tried to achieve by equation conversion MMC submodule Norton equivalent expression formulas, obtain thevenin equivalent circuit accordingly.

Step 2：Single submodule is composed in series bridge arm equivalent model, then bridge arm equivalent model is added to the whole change of current In device, whole circuit network is solved using electromagnetic transient simulation software, obtains the bridge arm current value of each bridge arm.

Step 3：By the anti-builtin voltage for solving each submodule of the bridge arm current value tried to achieve, it is each to complete single port MMC The renewal of whole submodule internal informations inside bridge arm.

Brief description of the drawings

Fig. 1 is D-HBSM topological structures and its schematic equivalent circuit.

Embodiment

The present invention provides a kind of general single port submodule MMC electro-magnetic transient generalized equivalent modeling methods；Below will be with double Half-bridge submodule MMC（Double half bridge sub-module MMC, DHB-MMC）Exemplified by, with reference to attached drawing to the present invention Modeling procedure be further described in detail.

Fig. 1 is single D-HBSM topological structures and its concomitant circuit schematic diagram, by the IGBT of single D-HBSM in Fig. 1 (a) And its anti-paralleled diode respectively with a variable-conductance (G1~G8) equivalent replacement.In PSCAD/EMTDC, when IGBT is turned on, Variable-conductanceGTakeG _ON=100S；When IGBT is turned off, variable-conductanceGTakeG _OFF=1e-6S.At the same time willtMoment single D-HBSM's Submodule capacitance C is discrete to turn to a conductanceG _CWith a historical current sourceI _CEQ(t- Δ T) it is in parallel.So as to obtaintMoment is single Shown in the equivalent circuit of a D-HBSM such as Fig. 1 (b).

Step 1：In order to list nodal voltage equation, first double half-bridge submodules are sorted out.The submodule is double capacitances Submodule, first sets submodule totally 6 nodes, and node 1 and 2 is external node,k ₁=1,k ₂=1, capacitive node isi=1,j=3,p=4,q=2, remaining node is respectively 5 and 6,i、jWithp、qEqual situation is not occurred, therefore without the feelings for occurring sharing pole plate Condition, without carrying out short-circuit contraction, it may be determined that submodule is 6 nodes.

To any double half-bridge submodules, it is reference mode with node 2, then can setsV ₂=0, row write nodal voltage equation such as public affairs Formula（1）It is shown：

(1)

Formula 1 carries out piecemeal according to interior exterior node, can be rewritten as following form：

(2)

Using the quick nested thinking solved, i.e., the information of internal node is represented with the information of external node, is only retained exterior Node, eliminates internal node.Formula (2) is expanded into following two formula：

(3)

(4)

It can be solved from formula (4)V _INIf it can obtainV _EX, then (5) formula can be utilized to solve each submodule capacitor voltage.

(5)

(5) substitution (3) can be obtained：

(6)

In formula (6), order：

(7)

(8)

The equation shaped like (9) may finally then be obtained：

(9)

WhereinY _EXFor Norton equivalent conductance,J _EX ^TsfFor Norton equivalent current source.Obviously, when known to promise parameter, equivalent circuit Dai Weinan parameters be also known.

Step 2：The bridge arm equivalent model that 6 bridge arms of single port MMC are all tried to achieve with step 1 is replaced, and is added to whole In single port MMC artificial circuit networks, whole circuit network is solved by electromagnetic transient simulation software afterwards, is obtained each The bridge arm current value of bridge arm.

Step 3：Any submodule is obtained according to formula (9)V _EX, and substitute into formula (5) and obtainV _INValue so that more New submodule internal capacitance information of voltage.

Claims

A kind of 1. single port submodule MMC electro-magnetic transient generalized equivalent modeling methods；

It is characterized in that, the present invention by nested rapid solving algorithm by the single bridge arms of single port MMC in whole submodule Portion node equivalent eliminates, the equivalent circuit by whole bridge arm equivalent for only surplus external node, to it is exterior equivalent while, can The various internal informations for completely retaining single bridge arm are not in the situation of loss, are a kind of accurate equivalent models；

This method comprises the following steps：

Step 1：Processing is numbered to all nodes, isolates internal node and external node；Row are write each submodule and are corresponded to Nodal voltage equation；To the processing of nodal voltage equation piecemeal, based on the thinking of quick nested derivation algorithm, external node is utilized Information represent internal node so that equivalent cancellation internal node；Replaced by equation, solve submodule Norton equivalent electricity The expression formula on road, and thevenin equivalent circuit is solved accordingly；

Step 2：Single submodule is composed in series bridge arm equivalent model, then bridge arm equivalent model is added to whole transverter In, whole circuit network is solved using electromagnetic transient simulation software, obtains the bridge arm current value of each bridge arm；

Step 3：On the basis of step 2, each node voltage inside submodule is obtained by the anti-solution of the bridge arm current tried to achieve, is completed The renewal of submodule internal information.
2. a kind of general single port submodule MMC electro-magnetic transient generalized equivalent modeling methods according to claim 1, it is special Sign is, step 1 arrives step 3, and previous step is the basis that latter step performs, ring between this 3 modeling procedures Ring interlocks, order performs, and is an organic, indivisible entirety.