Summary of the invention
The object of the invention is to propose a kind of equivalent simulation calculation modeling method that makes the full-bridge cascade multi-level transverter that simulation calculation is quick, result of calculation is reliable and stable.
The equivalent simulation calculation modeling method of full-bridge cascade multi-level transverter of the present invention, described full-bridge cascade multi-level transverter is comprised of six brachium pontis, every two brachium pontis series connection forms a facies unit, every brachium pontis is by cascade submodule, guide switch and brachium pontis reactance L are composed in series, wherein submodule includes insulated gate bipolar thyristor IGBT1, IGBT2, IGBT3, IGBT4, diode D1, D2, D3, D4 and capacitor C, switching device branch road of every insulated gate bipolar thyristor and a diode reverse formation in parallel, the cascade of every two switching device branch roads is also in parallel with capacitor C, the node NF docking with the external world the tie point of two switching device branch roads cascade as submodular circuits, NT, the equivalent simulation calculation modeling method of full-bridge cascade multi-level transverter comprises the following steps:
1) capacitor C in submodule is substituted to controlled time-varying reactance equivalence for the parallel branch of IGBT1, IGBT2, IGBT3, IGBT4 and diode D1, D2, D3, D4 with Bei Ruilong equivalent calculation model;
2) according to solve parallel branch that the previous moment t-Δ t switching tube start pulse signal of t constantly determines IGBT1, IGBT2, IGBT3, IGBT4 and diode D1, D2, D3, D4 with controlled time-varying reactance in the t-Δ t resistance in the moment;
3) according to step 2) in definite t-Δ t IGBT1, IGBT2, IGBT3, IGBT4 and the resistance of the parallel branch of diode D1, D2, D3, D4 and the electric current of t-Δ t moment submodule external interface are tried to achieve constantly the flow through current i of submodule electric capacity of t-Δ t constantly
_{c}(t-Δ t);
4) according to the current i that solves the t-Δ t moment submodule electric capacity obtaining in step 3)
_{c}(t-Δ t) and t-2 Δ t historic state record amount (the voltage v of capacitor C constantly
_{c}the current i of (t-2 Δ t), capacitor C
_{c}(t-2 Δ t)) adopt trapezoidal integration to solve to obtain the t-Δ t voltage v of submodule capacitor C constantly
_{c}(t-Δ t);
5) according to the voltage v of the t-Δ t submodule capacitor C calculating in step 3), step 4)
_{c}the current i of (t-Δ t), capacitor C
_{c}the equivalent calculation model of definite t moment submodule in (t-Δ t) and t switching tube start pulse signal substitution step 1) constantly;
6) the t equivalent calculation model simplification of submodule is constantly become to an equivalent calculation model that only comprises the Dai Weinan pattern of historical voltage source and resistance;
7) will in step 6), obtain the merging of connecting of a plurality of submodule equivalent calculation models, obtain the equivalent calculation model of full-bridge cascade multi-level converter bridge arm;
8), according to the concrete topological structure of submodule, determine the place an order booster diode position of the outside access of a brachium pontis of in submodule whole locking situations of switching device.
Above-mentioned steps 1), in, the inverse parallel branch road of insulated gate bipolar thyristor IGBT1, IGBT2, IGBT3, IGBT4 and diode D1, D2, D3, D4 is taken as a resistance and treated by the resistance branch of insulated gate bipolar thyristor triggering impulse control in the process of solving circuit numerical solution;
Switching branches in above-mentioned submodular circuits is taken as resistance and treated by resistance branch G1, G2, G3, the G4 of the control of insulated gate bipolar thyristor triggering impulse in the process of solving circuit numerical solution.
Said method is applicable to the full-bridge cascade multi-level rectifier in flexible DC power transmission field, is also applicable to the transverter topology that other adopt full-bridge cascade.
Said method is applicable to cascade multi-level STATCOM.
The present invention proposes a kind of based on Dommel equivalent calculation principle, the equivalent Simulation Calculation of full-bridge cascade multi-level transverter realizing in general electromagnetic transient simulation calculates.This method is externally equivalent to an independent Dommel equivalent calculation model by the brachium pontis of full-bridge cascade multi-level transverter, only introduces a variableimpedance branch road in system node admittance matrix; The electric current and voltage value of brachium pontis equivalent circuit is all unifiedly calculated in network matrix; Electric capacity quantity of state in brachium pontis submodule adopts trapezoidal integration to upgrade.Adopt this method can make that simulation calculation is quick, result of calculation is reliable and stable.The present invention is a kind of equivalent simulation calculation modeling method that makes the full-bridge cascade multi-level transverter that simulation calculation is quick, result of calculation is reliable and stable.Institute of the present invention extracting method is not only applicable to the full-bridge cascade multi-level rectifier in flexible DC power transmission field, is also applicable to the transverter topology that other adopt full-bridge cascade, as cascade multi-level STATCOM.
Embodiment
The equivalent simulation calculation modeling method of full-bridge cascade multi-level transverter of the present invention, the structure of a facies unit of described full-bridge cascade multi-level transverter as shown in Figure 1, facies unit is in series by two brachium pontis, and every brachium pontis is composed in series by cascade submodule, guide switch and brachium pontis reactance L.Wherein the structure of submodule as shown in Figure 2, include insulated gate bipolar thyristor IGBT1, IGBT2, IGBT3, IGBT4, diode D1, D2, D3, D4 and capacitor C, switching device branch road of every insulated gate bipolar thyristor and a diode reverse formation in parallel, the cascade of every two switching device branch roads is also in parallel with capacitor C, using the tie point of two switching device branch roads cascade as submodular circuits, with extraneous node NF, the NT docking, the equivalent simulation calculation modeling method of full-bridge cascade multi-level transverter comprises the following steps:
1) capacitor C in submodule is substituted to controlled time-varying reactance equivalence for the parallel branch of insulated gate bipolar thyristor IGBT1, IGBT2, IGBT3, IGBT4 and diode D1, D2, D3, D4 with Bei Ruilong equivalent calculation model;
2) according to solve parallel branch that the previous moment t-Δ t switching tube start pulse signal of t constantly determines insulated gate bipolar thyristor IGBT1, IGBT2, IGBT3, IGBT4 and diode D1, D2, D3, D4 with controlled time-varying reactance in the t-Δ t resistance in the moment;
3) according to step 2) in definite t-Δ t insulated gate bipolar thyristor IGBT1, IGBT2, IGBT3, IGBT4 and the resistance of the parallel branch of diode D1, D2, D3, D4 and the electric current of t-Δ t moment submodule external interface are tried to achieve constantly the flow through current i of submodule electric capacity of t-Δ t constantly
_{c}(t-Δ t);
4) according to the current i that solves the t-Δ t moment submodule electric capacity obtaining in step 3)
_{c}(t-Δ t) and t-2 Δ t historic state record amount (the voltage v of capacitor C constantly
_{c}the current i of (t-2 Δ t), capacitor C
_{c}(t-2 Δ t)) adopt trapezoidal integration to solve to obtain the t-Δ t voltage v of submodule capacitor C constantly
_{c}(t-Δ t);
5) according to the current status v of the t-Δ t submodule capacitance voltage C calculating in step 3), step 4)
_{c}(t-Δ t), i
_{c}the equivalent calculation model of definite t moment submodule in (t-Δ t) and t switching tube start pulse signal substitution step 1) constantly;
6) the t equivalent calculation model simplification of submodule is constantly become to an equivalent calculation model that only comprises the Dai Weinan pattern of historical voltage source and resistance;
7) will in step 6), obtain the merging of connecting of a plurality of submodule equivalent calculation models, obtain the equivalent calculation model of full-bridge cascade multi-level converter bridge arm;
8), according to the concrete topological structure of submodule, determine the place an order booster diode position of the outside access of a brachium pontis of in submodule whole locking situations of switching device.
Above-mentioned steps 1), in, the inverse parallel branch road of insulated gate bipolar thyristor IGBT1, IGBT2, IGBT3, IGBT4 and diode D1, D2, D3, D4 is taken as a resistance and treated by the resistance branch of IGBT trigger pulse control in the process of solving circuit numerical solution
Switching branches in above-mentioned submodular circuits is taken as resistance and treated by resistance branch G1, G2, G3, the G4 of the control of insulated gate bipolar thyristor triggering impulse in the process of solving circuit numerical solution.
Said method is applicable to the full-bridge cascade multi-level rectifier in flexible DC power transmission field, is also applicable to the transverter topology that other adopt full-bridge cascade.
Said method is applicable to cascade multi-level STATCOM.
Below in conjunction with accompanying drawing, describe content of the present invention in detail.
As shown in Figure 3, by the switch in the submodular circuits in accompanying drawing 2 with controlled time-varying reactance G1, G2, G3, G4 equivalence, as shown in Figure 3, electric capacity substitutes with Dommel equivalent calculation model, as controllable current source ICD in accompanying drawing 3 leads as shown in the parallel branch of GCD with electricity, the bleeder resistance RP of electric capacity in accompanying drawing 2 is led to GP equivalence by electricity as shown in Figure 3, and identical with accompanying drawing 2 of the NF in accompanying drawing 3, NT, is the circuit tie point of submodule and extraneous network.
In accompanying drawing 3
$\begin{array}{c}\mathrm{GCD}=\frac{2C}{\mathrm{\Δt}}\\ \mathrm{ICD}=-{i}_{c}(t-\mathrm{\Δt})-\frac{2C}{\mathrm{\Δt}}{v}_{c}(t-\mathrm{\Δt})\end{array}---\left(1\right)$
Δ t is simulation step length
The switching tube turn-on condition adopting in the present invention is switching tube forward voltage >=0, and turn-off criterion is switching tube forward current <=0.For fear of the on off state of simulation step length intermediate switch pipe, change and cause the variation of switching tube branch road resistance, suppose IGBT and diode open/close power-off lead identical, thereby avoid to emulation constantly intermediate switch state variation carry out the problem that interpolation produces.According to t time trigger signal, the expression that can obtain G1, G2, G3, G4 in accompanying drawing 3 is as shown in table 1:
Table 1
In table, FP1, FP2, FP3, FP4 are the trigger pip of IGBTT1, T2, T3, T4, and " 1 " represents open-minded, and " 0 " representative is turn-offed.GON/GOFF represents that the power-off of opening/close of IBGT and diode leads.
The system Dommel bus admittance matrix of not participating in last step-length due to the electric capacity in submodule in equivalent calculation model directly solves, and therefore cannot directly obtain the quantity of state i in formula (1) by current/voltage measuring module
_{c}(t-Δ t) and v
_{c}(t-Δ t) value, thus need in the program of equivalent model, push back again a step-length.Accompanying drawing 4 is t-Δ t full-bridge type submodule equivalent calculation model constantly.
I in accompanying drawing 4
_{arm}the equivalent calculation model that (t-Δ t) is whole brachium pontis participates in the given value after t-Δ t moment system matrix solves.G1 ' in accompanying drawing 4, G2 ' G3 ', G4 ' are according to the t-Δ t definite switching device equivalent resistance of trigger pulse (FPU, FPL) constantly, GCP in accompanying drawing 4, GP, NF, NT are identical with the definition in accompanying drawing 3, and the ICD ' in accompanying drawing 4 represents the t-Δ t controllable current source of the Dommel equivalent calculation model of electric capacity constantly.
4 can directly try to achieve i with reference to the accompanying drawings
_{c}(t-Δ t), asks electric current and the ICD ' sum of the GCD branch road of flowing through, and its expression formula is as follows:
${i}_{c}(t-\mathrm{\Δt})=\frac{{G1}^{\′}\·\mathrm{GCD}\·{i}_{\mathrm{arm}}(t-\mathrm{\Δt})+[{G1}^{\′}\·{G2}^{\′}+({G1}^{\′}+{G2}^{\′})\·\mathrm{GP}]\·{\mathrm{ICD}}^{\′}}{{G1}^{\′}\·{G2}^{\′}+({G1}^{\′}+{G2}^{\′})\·\mathrm{GCP}}---\left(2\right)$
In formula
GCP=GCD+GP
GHB=G1'·G2'·G3'+G1'·G2'·G4'+G1'·G3'·G4'+G2'·G3'·G4'
+G1'·G3'·GCP+G1'·G4'·GCP+G2'·G3'·GCP+G2'·G4'·GCP
$\mathrm{GLB}=\frac{1}{\frac{1}{{G1}^{\′}}+\frac{1}{{G2}^{\′}}}$
$\mathrm{GRB}=\frac{1}{\frac{1}{{G3}^{\′}}+\frac{1}{{G4}^{\′}}}$
Adopt trapezoidal integration, try to achieve v
_{c}(t-Δ t) is:
${v}_{c}(t-\mathrm{\Δt})={v}_{c}(t-2\mathrm{\Δt})+\frac{\mathrm{\Δt}}{2C}({i}_{c}(t-\mathrm{\Δt})+{i}_{c}(t-2\mathrm{\Δt}))---\left(3\right)$
The v calculating
_{c}(t-Δ t) can export the use of the algoritic module of controlling for capacitance voltage balance.By formula (2) and formula (3) substitution (1), through merging to simplify with pause/Dai Weinan of promise, transform, can obtain the equivalent calculation model of submodule as shown in Figure 5, UMD in accompanying drawing 5 is the voltage source in submodule Dai Weinan equivalent model, RMD is the interior resistance in submodule Dai Weinan equivalent model, and NF, NT are identical with the definition in accompanying drawing 3.
The equivalent calculation model that the equivalent calculation model combination of a plurality of submodule Dai Weinan patterns of trying to achieve through said method can be obtained to brachium pontis as shown in Figure 6, UAD in accompanying drawing 6 is the voltage source in brachium pontis Dai Weinan equivalent model, RAD is the interior resistance in brachium pontis Dai Weinan equivalent model, and NF and NT are the circuit tie point of brachium pontis and extraneous network.In figure:
$\begin{array}{c}\mathrm{RAD}=\underset{i=1}{\overset{N}{\mathrm{\Σ}}}{\mathrm{RMD}}_{i}\\ \mathrm{UAD}=\underset{i=1}{\overset{N}{\mathrm{\Σ}}}{\mathrm{UMD}}_{i}\end{array}---\left(4\right)$
In formula, N is the submodule quantity of brachium pontis cascade.The self-defined tributary interface that obtains recycling after the Dai Weinan pattern equivalent calculation model of brachium pontis the simulation software of EMTP pattern, solves this Equivalent Model and extraneous node networking.
In full-bridge cascade multi-level transverter, IBGT turn-offs in (being brachium pontis locking) situation, in submodule, only comprise diode element, in the algorithm of fixed step size simulation software, conventionally need to carry out the mistake of interpolation to avoid numerical evaluation to produce to this switching time and state variable of naturally turn-offing device.Yet because the User Defined code in the simulation software in EMTP pattern only carries out computing constantly in emulation, cannot carry out computing to two emulation middle moment constantly, therefore the present invention utilizes the simulation software self of EMTP pattern the diode model providing and the brachium pontis equivalent calculation model of above mentioning to combine that locking process is carried out to emulation, concrete modeling as shown in Figure 7, wherein switch Brk and Brk ' are by the signal controlling that unblocks, release constantly switch Brk is closed, Brk ' opens, locking constantly switch Brk is opened, Brk ' closure, UAD, RAD, NF, NT is identical with the definition in accompanying drawing 6.G1=GOFF+GON in the derivation of idle interval full-bridge type submodule equivalent calculation model, G2=GOFF+GOFF, G3=GOFF+GON, G4=GOFF+GOFF.