CN113191106A - Hybrid MMC full-state efficient electromagnetic transient simulation method and system - Google Patents
Hybrid MMC full-state efficient electromagnetic transient simulation method and system Download PDFInfo
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Abstract
The application discloses a hybrid MMC full-state efficient electromagnetic transient simulation method and system. Judging the unlocking state of the hybrid MMC according to an unlocking signal of the hybrid MMC, wherein the bridge arm submodule comprises a bridge arm half-bridge submodule and a bridge arm full-bridge submodule; according to the unlocking state of the mixed MMC, thevenin equivalence is carried out on the bridge arm half-bridge submodule, and a thevenin equivalent branch of the mixed MMC half-bridge submodule is determined; according to the unlocking state of the hybrid MMC, thevenin equivalence is carried out on the bridge arm full-bridge submodule, and a thevenin equivalent branch of the hybrid MMC full-bridge submodule is determined; according to mixed type MMC half-bridge submodule thevenin equivalent branch with mixed type MMC full-bridge submodule thevenin equivalent branch, obtain mixed type MMC full-state high efficiency model, carry out electromagnetic transient state simulation calculation.
Description
Technical Field
The application relates to the technical field of power systems, in particular to a hybrid MMC full-state efficient electromagnetic transient simulation method and system.
Background
Modular Multilevel Converters (MMC) quickly receive high attention at home and abroad due to the advantages of small harmonic content, strong fault handling capability, low switching frequency, good expansion performance, convenience for modular design and the like. At present, the MMC is rapidly developed from low-voltage and small-capacity demonstration projects to high-voltage and large-capacity projects gradually, unique technical advantages and economic benefits are shown in the occasions of asynchronous networking, wind power plant grid connection, city center power supply, conventional direct current hybrid connection and the like, and the MMC becomes an optimal mainstream topology of a flexible direct current power transmission system.
The hybrid MMC formed by the half-bridge submodule and the full-bridge submodule has the direct-current fault ride-through capability and the economy, and has a wide application prospect. With continuous planning and commissioning of the hybrid MMC, a hybrid MMC electromagnetic transient simulation method is researched, a hybrid MMC electromagnetic transient model suitable for a large power grid is established, and great significance is brought to project early-stage design such as flexible direct-current system debugging, large-scale alternating-current and direct-current power grid fault analysis, stability analysis and control protection strategy design and verification.
The method aims at solving the problems that the hybrid MMC submodules are numerous in number, low in simulation efficiency and not suitable for full electromagnetic transient simulation analysis of a large-scale power system. The half-bridge MMC simulation method is applied to electromagnetic transient simulation of full-bridge MMC and mixed MMC, a mixed MMC Thevenin equivalent model is established, and high-precision simulation under a mixed MMC unlocking mode can be realized through the equivalent. In electromagnetic transient simulation, however, many cases involve latch-up mode. Aiming at the flexible and complex working state under the hybrid MMC locking mode, the method faces the interpolation problem. How to correctly simulate the locking mode of the hybrid MMC so as to realize the unlocking mode of the hybrid MMC with high precision and high efficiency simulation is a difficulty for the full-state electromagnetic transient simulation of the hybrid MMC. In the prior art, the MMC locking mode is simulated by controlling the closing of a switch by means of a self-contained diode model of PSCAD/EMTDC. However, this method has the following disadvantages: 1) the single-bridge arm mixed MMC needs 6 equivalent diodes, so that the number of internal nodes is increased, and the simulation efficiency of the model is reduced; 2) in the unlocking mode, unnecessary interpolation calculation of the diode is still carried out according to the action criterion, so that the simulation efficiency of the hybrid MMC is further reduced; 3) the capacitance and voltage sequencing of the partial full-state bridge arm equivalent model is still carried out in a locking mode, so that the calculation efficiency of the hybrid MMC model is seriously reduced; 4) depending on the interpolation algorithm of a foreign PSCAD simulation platform, the risk of limited and unavailable platform exists.
Disclosure of Invention
The embodiment of the disclosure provides a hybrid MMC full-state efficient electromagnetic transient simulation method and system, so as to at least solve the problem of how to correctly simulate a hybrid MMC locking mode in the prior art. And simulating an MMC latching mode by closing a control switch by virtue of a diode model carried by the PSCAD/EMTDC. However, this method has the following disadvantages: 1) the single-bridge arm mixed MMC needs 6 equivalent diodes, so that the number of internal nodes is increased, and the simulation efficiency of the model is reduced; 2) in the unlocking mode, unnecessary interpolation calculation of the diode is still carried out according to the action criterion, so that the simulation efficiency of the hybrid MMC is further reduced; 3) the capacitance and voltage sequencing of the partial full-state bridge arm equivalent model is still carried out in a locking mode, so that the calculation efficiency of the hybrid MMC model is seriously reduced; 4) the technical problem of the risk of limited and unavailable platform exists depending on the interpolation algorithm of a foreign PSCAD simulation platform.
According to an aspect of the embodiments of the present disclosure, a hybrid MMC full-state efficient electromagnetic transient simulation method is provided, including: judging the unlocking state of the hybrid MMC according to the unlocking signal of the hybrid MMC, wherein the bridge arm submodule comprises a bridge arm half-bridge submodule and a bridge arm full-bridge submodule; according to the unlocking state of the mixed MMC, thevenin equivalence is carried out on the bridge arm half-bridge submodule, and a thevenin equivalent branch of the mixed MMC half-bridge submodule is determined; according to the unlocking state of the hybrid MMC, thevenin equivalence is carried out on the bridge arm full-bridge submodule, and a thevenin equivalent branch of the hybrid MMC full-bridge submodule is determined; according to mixed type MMC half-bridge submodule thevenin equivalent branch with mixed type MMC full-bridge submodule thevenin equivalent branch, obtain mixed type MMC full-state high efficiency model, carry out electromagnetic transient state simulation calculation.
According to another aspect of the embodiments of the present disclosure, there is also provided a hybrid MMC full-state high-efficiency electromagnetic transient simulation system, including: the unlocking state judging module is used for judging the unlocking state of the hybrid MMC according to an unlocking signal of the hybrid MMC, and the bridge arm submodule comprises a bridge arm half-bridge submodule and a bridge arm full-bridge submodule; the half-bridge sub-module Thevenin equivalent module is used for carrying out Thevenin equivalent on the bridge arm half-bridge sub-module according to the unlocking state of the mixed MMC to determine a Thevenin equivalent branch of the mixed MMC half-bridge sub-module; the full-bridge sub-module Thevenin equivalent module is used for carrying out Thevenin equivalent on the bridge arm full-bridge sub-module according to the unlocking state of the hybrid MMC to determine a Thevenin equivalent branch of the hybrid MMC full-bridge sub-module; and the electromagnetic transient simulation calculation module is used for obtaining a hybrid MMC full-state efficient model according to the hybrid MMC half-bridge submodule Thevenin equivalent branch and the hybrid MMC full-bridge submodule Thevenin equivalent branch, and performing electromagnetic transient simulation calculation.
According to the full-state efficient electromagnetic transient simulation method for the hybrid MMC, the unlocking state and the locking state of the hybrid MMC can be simulated at the same time, high simulation precision is guaranteed, and meanwhile the calculation efficiency of a model is improved remarkably, so that the full-electromagnetic transient simulation method is more suitable for full-electromagnetic transient simulation analysis of a large-scale alternating current and direct current power grid. The method is reasonable, efficient and more suitable for full electromagnetic simulation calculation of a large power grid.
Drawings
The accompanying drawings, which are included to provide a further understanding of the disclosure and are incorporated in and constitute a part of this application, illustrate embodiment(s) of the disclosure and together with the description serve to explain the disclosure and not to limit the disclosure. In the drawings:
fig. 1 is a schematic flow chart of a hybrid MMC full-state efficient electromagnetic transient simulation method according to an embodiment of the present disclosure;
fig. 2 is a schematic flow chart of a hybrid MMC full-state efficient electromagnetic transient simulation method according to an embodiment of the present disclosure;
fig. 3 is a schematic diagram of a bridge arm half-bridge submodule locking equivalent model according to an embodiment of the present disclosure;
fig. 4 is a schematic diagram of a bridge arm full-bridge submodule locking equivalent model according to the embodiment of the present disclosure;
fig. 5 is a full-state equivalent model diagram of a hybrid MMC according to an embodiment of the disclosure;
fig. 6 is a diagram of a 5-level double-ended hybrid MMC-HVDC test system provided in accordance with an embodiment of the present disclosure;
fig. 7 is a comparison graph of waveforms of a 5-level hybrid MMC according to an embodiment of the disclosure;
fig. 8 is a comparison graph of waveforms of a 201-level hybrid MMC according to an embodiment of the disclosure;
fig. 9 is a schematic diagram of a hybrid MMC full-state high-efficiency electromagnetic transient simulation system according to an embodiment of the present disclosure.
Detailed Description
The exemplary embodiments of the present invention will now be described with reference to the accompanying drawings, however, the present invention may be embodied in many different forms and is not limited to the embodiments described herein, which are provided for complete and complete disclosure of the present invention and to fully convey the scope of the present invention to those skilled in the art. The terminology used in the exemplary embodiments illustrated in the accompanying drawings is not intended to be limiting of the invention. In the drawings, the same units/elements are denoted by the same reference numerals.
Unless otherwise defined, terms (including technical and scientific terms) used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. Further, it will be understood that terms, such as those defined in commonly used dictionaries, should be interpreted as having a meaning that is consistent with their meaning in the context of the relevant art and will not be interpreted in an idealized or overly formal sense.
According to a first aspect of the present embodiment, there is provided a hybrid MMC full-state efficient electromagnetic transient simulation method 100, as shown in fig. 1, the method 100 including:
s102, judging the unlocking state of the hybrid MMC according to the unlocking signal of the hybrid MMC, wherein the bridge arm submodule comprises a bridge arm half-bridge submodule and a bridge arm full-bridge submodule;
s104, according to the unlocking state of the mixed MMC, carrying out thevenin equivalence on the bridge arm half-bridge sub-module, and determining a thevenin equivalent branch of the mixed MMC half-bridge sub-module;
s106, according to the unlocking state of the hybrid MMC, carrying out thevenin equivalence on the bridge arm full-bridge submodule to determine a thevenin equivalent branch of the hybrid MMC full-bridge submodule;
and S108, obtaining a hybrid MMC full-state efficient model according to the hybrid MMC half-bridge sub-module Thevenin equivalent branch and the hybrid MMC full-bridge sub-module Thevenin equivalent branch, and performing electromagnetic transient simulation calculation.
Specifically, in the full-state efficient electromagnetic transient method for the hybrid MMC, firstly, a deblocking signal of the hybrid MMC is detected, then Thevenin equivalence is respectively carried out on a bridge arm half-bridge sub-module and a bridge arm full-bridge sub-module, then Thevenin equivalence is carried out on a bridge arm inductance, finally, a full-state bridge arm model of the hybrid MMC is obtained, and electromagnetic transient simulation calculation is carried out. The method fully utilizes the locking characteristics of a half-bridge submodule and a full-bridge submodule in the mixed MMC, optimizes a locking equivalent method and improves the simulation efficiency of a locking mode of the mixed MMC; and according to the modulation characteristics of the hybrid MMC, a flexible stack sorting capacitance-voltage sorting algorithm is adopted, so that the simulation efficiency of the hybrid MMC unlocking mode is improved.
The embodiment comprises the following steps:
(1) and detecting an unlocking and locking signal of the mixed MMC, judging the unlocking and locking state of the mixed MMC, and determining a submodule capacitor voltage sequencing algorithm.
(2) And carrying out thevenin equivalent on the bridge arm half-bridge sub-module, and solving the thevenin equivalent branch of the mixed MMC half-bridge sub-module.
(3) And carrying out thevenin equivalence on the bridge arm full-bridge submodule, and solving a thevenin equivalent branch of the hybrid MMC full-bridge submodule.
(4) Solving the Thevenin equivalent branch of the bridge arm inductance to obtain a hybrid MMC full-state efficient model, and performing electromagnetic transient simulation calculation.
Preferably, the step (1) includes:
step 101: and detecting a control signal of the hybrid MMC to judge the unlocking state of the hybrid MMC.
If the detection control signal is an unlocking signal, the hybrid MMC is in an unlocking state; and if the control signal is detected to be the locking signal, the hybrid MMC is in a locking state.
Step 102: and determining a sequencing algorithm of the sub-module capacitor voltage according to the unlocking and locking state of the hybrid MMC.
If the hybrid MMC is in a locking state, sequencing the capacitance voltages of the sub-modules is not carried out, and if the hybrid MMC is in an unlocking state, sequencing the capacitance voltages according to the number of the conducted sub-modules output by the controller to determine the state of each sub-module, specifically in step 103-step 107.
Step 103: numbering all sub-modules of the bridge arm, wherein the front Nh is a half-bridge sub-module, Nh+1, …, N is the full bridge submodule.
Step 104: according to a conduction signal N (t) output by a modulation link, determining the scale of an initial pile, and distinguishing a middle pile submodule from an outer pile submodule.
1) If N (t) < -N f2, then 1, …, NhThe half-bridge sub-modules quit and are sequentially numbered as Nh+1, …, N + N (t) submodules are placed in a heap with the number of construction elements Nf+ N (t) of the initial pile. The out-pile elements are N + N (t) +1, …, N is total to N (t) full-bridge submodules.
2) if-NfN is more than or equal to/2 and less than 0 (t), then 1, …, NhThe half-bridge sub-modules quit and are sequentially numbered as Nh+1,…,NhThe submodules of-N (t) are placed in a heap, and an initial heap with the number of elements of-N (t) is constructed. The numbering of the sub-modules outside the pile is Nh-N (t) +1, …, N, total Nf+ N (t) full bridge submodules.
3) If 0 ≦ N (t) < N/2, the submodules numbered 1, …, N (t) are sequentially placed into the heap to build an initial heap with the number of elements N (t). The sub-modules outside the pile are numbered as N (t) +1, …, N, and N-N (t) sub-modules.
4) If N (t) is more than or equal to N/2, sub-modules numbered 1, … and N-N (t) are sequentially put into the heap, and an initial heap with the number of elements N-N (t) is constructed. The sub-modules outside the pile are numbered as N-N (t) +1, …, N, and N (t) sub-modules.
Step 105: according to iarmThe direction and N (t) values determine the properties of the initial heap.
If iarmIs not less than 0 and
the initial heap built is a large top heap.
If iarmIs not less than 0 and
the initial heap built is a small top heap.
If iarmIs < 0 and
the initial heap built is a small top heap.
If iarmIs < 0 and
the initial heap built is a large top heap.
Step 106: and comparing the capacitor voltage pointed by the submodule serial number outside the stack with the voltage pointed by the submodule serial number of the root node at the top of the stack in sequence.
Taking the large top stack as an example, if the capacitor voltage pointed by the root node submodule number is greater than the capacitor voltage pointed by the out-of-stack submodule number, the numbers of the root node submodule and the out-of-stack submodule are exchanged, and the structure of the large top stack is updated, so that the in-stack submodule meets the property of the large top stack. And if the capacitor voltage pointed by the serial number of the root node submodule is smaller than the capacitor voltage pointed by the serial number of the out-of-pile submodule, continuing to compare with the next out-of-pile submodule.
Step 107: and after the root node sub-module is compared with the out-of-pile sub-module, determining the sub-module number to be input according to N (t).
1) if-Nf/2≤N(t)≤And N/2, determining that the submodule inside the pile is input, and the submodule outside the pile is withdrawn.
2) If N (t) < -NfAnd/2 or N (t) is greater than N/2, the in-pile sub-module is determined to exit, and the out-pile sub-module is input.
Preferably, the step (2) includes:
step 201: and determining an equivalent method of the bridge arm half-bridge submodule according to the state of the mixed MMC. And if the hybrid MMC is in an unlocking state, determining the Thevenin equivalent branch of each half-bridge sub-module by adopting a half-bridge sub-module unlocking equivalent method according to the half-bridge sub-module state determined in the step 107, and then performing series superposition to obtain the Thevenin equivalent branch of the bridge arm half-bridge sub-modules. If the hybrid MMC is in blocking mode, steps 202-205 are taken.
Step 202: based on the simulation step length and the integral algorithm of the step, the virtual diode model is equivalent to the Thevenin branch, and the equivalent resistance is solved
And equivalent voltage
All half-bridge sub-modules in the bridge arm are equivalent to thevenin branch circuits in a capacitance series connection mode, and solution is carried out
And
step 203: equivalent resistance of half-bridge submodule worn on Winan model
And equivalent voltage
And after the calculation is finished, solving the voltage and current of the virtual diode model port according to the voltage of each node of the MMC.
Step 204: and judging whether the calculation of each virtual diode model is correct or not according to the current step state and the previous step state.
Case 1: if the virtual diode model in the previous step is in a cut-off state and the voltage at the two ends of the virtual diode model in the current step is less than 0, the calculation is correct, and the diode is still in the cut-off state.
Case 2: if the virtual diode model in the previous step is in a cut-off state and the voltage at two ends of the virtual diode model in the current step is greater than 0, the calculation is wrong, and the diode is turned on. Interpolation is carried out according to historical voltage and the voltage of the step, the zero crossing moment of the voltage is searched, and the variable resistance value is modified to be at the zero crossing moment
Step 202 is re-executed, and the voltage and current of the whole network are solved again.
Case 3: if the virtual diode model in the previous step is in a conducting state and the current of the virtual diode in the current step is larger than 0, the calculation is correct, and the diode is still in the conducting state.
Case 4: if the virtual diode model in the previous step is in a conducting state and the current of the virtual diode in the current step is less than 0. The calculation is wrong and the diode should be turned off. Interpolation is carried out according to historical current and current of the step, the zero crossing moment of the current is searched, and the variable resistance value is modified to be at the zero crossing moment
Step 202 is re-executed, and the voltage and current of the whole network are solved again.
Step 205: and after all the virtual diode models of the mixed MMC are calculated correctly, the calculation of the step is completed, and the state and the voltage and current values of the virtual diodes of the step are stored for the next step calculation.
Preferably, the step (3) includes:
step 301: and determining an equivalent method of the bridge arm full-bridge submodule according to the state of the hybrid MMC. And if the hybrid MMC is in an unlocking state, determining the Thevenin equivalent branch of each full-bridge submodule by adopting a bridge arm full-bridge submodule unlocking equivalent method according to the full-bridge submodule state determined in the step 107, and then performing series superposition to obtain the Thevenin equivalent branch of the bridge arm full-bridge submodule. If the hybrid MMC is in the locked mode, the following steps 302-305 are employed.
Step 302: the charging voltage u is obtained according to the following formulacharge(t) in the formula, uFBsm(t) represents the external voltage of the bridge arm submodule,
representing the equivalent voltage of the ith full-bridge sub-module capacitance.
Step 303: calculating the current step, adopting the historical state to prejudge the working state of the current step full-bridge submodule, determining the Thevenin branch of the bridge arm full-bridge submodule according to the working state, and solving the equivalent resistance
And equivalent voltage
After the calculation is finished, solving port voltage u of the bridge arm full-bridge submodule according to the voltage of each node of the MMCFBsm(t) and a charging voltage ucharge(t)。
Step 304: and judging whether the full-bridge submodule of each bridge arm is correctly calculated.
If the working state of the full-bridge submodule is judged to be positive, the following situations exist:
1)ucharge(t) > 0 and uFBsmIf (t) > 0, the prediction is correct.
2)ucharge(t) > 0 and uFBsmAnd (t) is less than or equal to 0, the pre-judgment is wrong, the working state of the bridge arm full-bridge submodule is negative input, the pre-judgment state is modified, and the calculation in the step is carried out again.
3)ucharge(t) is less than or equal to 0, the pre-judgment is wrong, the working state of the bridge arm full-bridge submodule is cut off, and u is greater than or equal to 0charge(T- Δ T) > 0, interpolation looks for ucharge(t) zero crossing t-At t-And (5) constantly modifying the working state of the full-bridge submodule to be cut off, and recalculating.
If the working state of the full-bridge submodule is judged to be negative input, the following situations exist:
1)ucharge(t) > 0 and uFBsmIf (t) is less than or equal to 0, the prejudgment is correct.
2)ucharge(t) > 0 and uFBsmIf the (t) > 0, the pre-judgment is wrong, the working state of the bridge arm full-bridge submodule is positive, the pre-judgment state is modified, and the calculation in the step is carried out again.
3)ucharge(t) is less than or equal to 0, the pre-judgment is wrong, the working state of the bridge arm full-bridge submodule is cut off, and u is greater than or equal to 0charge(T- Δ T) > 0, interpolation looks for ucharge(t) zero crossing t-At t-And (5) constantly modifying the working state of the full-bridge submodule to be cut off, and recalculating.
If the working state of the full-bridge submodule is judged to be cut off, the following situations exist:
1)uchargeif (t) is less than or equal to 0, the prejudgment is correct.
2)ucharge(t) > 0 and uFBsmIf (t) > 0, the prediction is wrong, and u is searched for by interpolationcharge(t) zero crossing t+At t+And (5) constantly modifying the working state of the full-bridge submodule into positive input, and recalculating.
3)ucharge(t) > 0 and uFBsmIf t is less than or equal to 0, then the prediction is wrong, and u is searched by interpolationcharge(t) zero crossing t+At t+And (5) constantly modifying the working state of the full-bridge submodule into negative input, and recalculating.
Step 305: after all the interpolation calculations of all bridge arm full-bridge submodules of the hybrid MMC are correct, the calculation in the step is completed, and the historical working state, the charging voltage and other variables of each bridge arm full-bridge submodule are stored for the next step of calculation.
The main steps of this example are as follows:
1) and detecting a control signal of the hybrid MMC to judge the unlocking state of the hybrid MMC.
2) And if the hybrid MMC is in an unlocking state, determining the switching state of each submodule based on a flexible stack capacitor voltage sequencing algorithm, and solving thevenin equivalent models of all submodules. And if the hybrid MMC is in a locking state, respectively obtaining thevenin equivalent branches of the bridge arm half-bridge submodule and the bridge arm full-bridge submodule.
3) Equivalent branch for solving thevenin of bridge arm inductance
4) And determining a hybrid MMC full-state equivalent model, and performing electromagnetic transient simulation calculation.
In the step 2), solving thevenin equivalent branch of the bridge arm half-bridge submodule is shown as an attached diagram 3.
The topology of the virtual diode is substantially consistent with the detailed electromagnetic transient model of the diode. The diode branch is composed of a variable resistor and a DC voltage source VfSeries, damping branch route damping capacitor CSAnd a damping resistor RSAre connected in series. Variable resistance value existing on-resistance
And cut-off resistance
Two value-taking modes are set according to the formulas (1) and (2), and the voltages at two ends of the diode model are taken in a regular mode
The current at both ends is negative and then taken
Respectively representing the thevenin equivalent resistance and the equivalent voltage of the virtual diode model. In a locking mode, submodule capacitor voltage sequencing is not carried out, and a Thevenin equivalent model of all half-bridge submodule capacitors of a bridge arm is directly determined according to the formulas (3) and (4).
In the formula, RONDenotes the on-resistance, ROFFDenotes the off resistance, RC、
Respectively representing the equivalent resistance and the equivalent voltage of the sub-module capacitor,
representing thevenin equivalent resistance and equivalent voltage of all the sub-module capacitors connected in series.
In the step 2), solving thevenin equivalent branch of the bridge arm full-bridge submodule is shown as an attached diagram 4.
Wherein closing switch S1 to a represents an off state; switch S1 is closed to b, switch S2 is closed to c representing a positive throw state; switch S1 is closed to b and switch S2 is closed to d representing a negative throw condition. U in the figureFBsmAnd (t) represents the external voltage of all the full-bridge submodules of the bridge arm.
In the step 4), the hybrid MMC full-state equivalent model is shown in fig. 5. 6 bridge arms of the hybrid MMC are respectively equivalent to a wear-Winan model and have corresponding equivalent voltage and equivalent resistance.
For example, in PSModel (power System model) electromagnetic transient simulation software, a hybrid MMC high-efficiency model (PSModel high-efficiency model) is developed to build a 5-level double-end MMC-HVDC test System as shown in fig. 6. Based on an MATLAB simulation platform, a detailed model (an MATLAB detailed model) is adopted to build the same 5-level double-end MMC-HVDC test system. And 2 mu s of simulation step length is adopted for simulation, and the working condition parameters are shown in tables 1 and 2.
TABLE 1 simulation example Primary System parameters
TABLE 2 simulation example control System parameters
And simulating 0.1s inversion side unlocking, 0.3s rectification side unlocking, changing the step of the active power instruction value of the 3.0s rectification side from 1.0pu to 0.8pu, generating a three-phase short circuit fault in the near area of a 4.0s inversion side alternating current system, and recovering the 4.12s fault.
The output waveforms of the PSModel high-efficiency model and the MATLAB detailed model are shown in fig. 7, where the red curve is the calculation result of the MATLAB detailed model, and the green curve is the calculation result of the PSModel high-efficiency model. FIG. 7(a) is a hybrid MMC sub-module capacitance voltage waveform; FIG. 7(b) is a rectified side DC voltage and highlights the DC voltage waveform at the moment of latching; FIG. 7(c) is a rectified side DC current and highlights the AC fault transient DC current waveform; fig. 7(d) shows an active power waveform on the inverter side.
Simulation results show that under the states of locking, fault, step response and the like of the mixed MMC, the calculation results of the PSMODel high-efficiency model are all in height consistency with the detailed MATLAB model, and the simulation precision error is about 0.1%.
In order to test the calculation speed of the PSMODel high-efficiency model, a mixed MMC full-state bridge arm equivalent model, namely a PSCAD equivalent model for short, is built on the basis of a PSCAD/EMTDC Professional V4.2.1 platform and by means of a built-in rapid sequencing algorithm of the PSCAD, a mixed MMC test system with two ends is built on the basis of the PSCAD platform, and a mixed MMC test system with two ends which is completely the same as the PSCAD is built on the basis of the PSMODel high-efficiency model. The simulation step size of 10 mu s is adopted, and the method is operated in an Intel i7-6500 CPU (the main frequency is 2.5 GHz).
Taking a single arm of 160 full bridges +40 half bridge submodules as an example, the typical waveforms on the ac side and the dc side are compared. The calculation results of the PSCAD equivalent model and the PSMODel efficient model are shown in FIG. 8, wherein a red curve is the PSCAD equivalent model, and a green curve is the PSMODel efficient model. Fig. 8(a) is a dc voltage waveform, fig. 8(b) is a dc current waveform, fig. 8(c) is an ac voltage waveform, and fig. 8(d) is an ac current waveform. FIG. 8 shows that the PSMODel efficient model is substantially consistent with the PSCAD equivalent model in terms of its calculation, whether the waveforms are DC-side or AC-side.
In order to verify the rapidity of the hybrid MMC full-state efficient electromagnetic transient simulation method provided by the invention, a hybrid MMC classical equivalent model is built in PSCAD/EMTDC, a 10 mu s simulation step length and 2.0s simulation time are adopted based on the two-end MMC-HVDC test system, wherein the hybrid MMC runs for 1.0s in a locking mode and runs for 1.0s in an unlocking mode. The numbers of half-bridge submodules and full-bridge submodules shown in table 3 are respectively adopted to count the simulation time of the PSMODel and PSCAD latching mode and the simulation time of the unlocking mode.
TABLE 3 MMC test System simulation time
Compared with simulation time of a PSCAD (power system computer aided design) and a PSMODel blocking mode, the PSMODel efficient model is based on the blocking equivalent method, and the simulation efficiency of the blocking mode is far higher than that of the PSCAD equivalent model. Compared with the calculation time of the PSCAD and PSMODel unlocking modes, when the number of the sub-modules is small, the interpolation calculation of the diodes of the PSCAD equivalent model and the internal nodes of the model are main factors influencing the simulation efficiency, the PSMODel efficient model avoids unnecessary interpolation calculation in the unlocking mode, the internal nodes are saved, and therefore the speed-up result is more obvious. When the number of the sub-modules is large, the sorting algorithm is a main factor influencing the calculation efficiency, and the PSMODel efficient model adopts the flexible heap sorting algorithm, so that the calculation efficiency is greatly improved compared with the PSCAD rapid sorting algorithm.
Therefore, no matter in a locking or unlocking mode, the PSMODel efficient model has high simulation precision, and meanwhile, the calculation speed is obviously higher than that of a PSCAD equivalent model. Therefore, according to the hybrid MMC full-state efficient electromagnetic transient simulation method, the unlocking state and the locking state of the hybrid MMC can be simulated at the same time, high simulation precision is guaranteed, and meanwhile the calculation efficiency of the model is remarkably improved, so that the method is more suitable for large-scale AC/DC power grid full-electromagnetic transient simulation analysis. The method is reasonable, efficient and more suitable for full electromagnetic simulation calculation of a large power grid.
Optionally, the determining the unblocking state of the hybrid MMC according to the unblocking signal of the hybrid MMC includes: determining a sorting algorithm of the bridge arm sub-modules according to the unlocking state; when the hybrid MMC is in a locking state, the bridge arm sub-modules are not sequenced; and when the hybrid MMC is in an unlocking state, sequencing the bridge arm sub-modules according to the sequencing algorithm and the number N (t) of the conduction sub-modules output by the controller, and determining the state of each sub-module.
Optionally, when the hybrid MMC is in an unlocked state, sorting the bridge arm sub-modules according to the number of conducting sub-modules output by the controller, and determining the state of each sub-module includes:
numbering the bridge arm sub-modules, wherein the total number of the bridge arm sub-modules is N, and the numbering of the half-bridge sub-modules is 1-NhNumber of full bridge submodule is Nh+1 to N; according to the number N (t) of the conduction sub-modules and the numbers 1-N of the half-bridge sub-moduleshAnd the number of the full bridge submodule is Nh+ 1-N, determining the scale of the initial pile, a pile neutron module and a pile external submodule; according to bridge arm current iarmThe direction and the number N (t) of the conducting sub-modules are used for determining the structure of the initial pile; comparing the capacitor voltage pointed by the serial number of the sub-module outside the pile with the capacitor voltage pointed by the serial number of the sub-module at the root node at the top of the pile in sequence, determining a comparison result, and updating the structure of the initial pile according to the comparison result; and determining the number of the bridge arm sub-modules to be input and determining the states of the bridge arm half-bridge sub-modules and the bridge arm full-bridge sub-modules according to the updated top stack structure and the number N (t) of the conduction sub-modules.
Optionally, according to the unblocking state of mixed type MMC, carry out thevenin equivalence to bridge arm half-bridge submodule, confirm mixed type MMC half-bridge submodule thevenin equivalent branch road, include: when the hybrid MMC is in an unlocking state, determining a thevenin equivalent branch of each bridge arm half-bridge submodule according to the state of the bridge arm half-bridge submodule; and (4) serially overlapping the Thevenin equivalent branches of all bridge arm half-bridge sub-modules in the bridge arm to determine the Thevenin equivalent branches of the bridge arm half-bridge sub-modules.
Optionally, according to the unblocking state of mixed type MMC, carry out thevenin equivalence to bridge arm half-bridge submodule, confirm mixed type MMC half-bridge submodule thevenin equivalent branch road, still include: when the hybrid MMC is in a locked state, the virtual diode model is equivalent to a Thevenin branch circuit based on the simulation step length and the integral algorithm of the step, and the equivalent resistance of the virtual diode model is determined
And equivalent voltage of the virtual diode model
All bridge arm half-bridge sub-modules in the bridge arm are equivalent to thevenin branch circuits in series connection through capacitors, and the equivalent resistors are used for
And equivalent voltage
Equivalent resistance of bridge arm half-bridge submodule wearing Winan model
And equivalent voltage
After the calculation is finished, solving the voltage and current of the virtual diode model port according to the voltage of each node of the MMC; judging whether the calculation of each virtual diode model is correct or not according to the current step state and the previous step state; and when all the virtual diode models of the hybrid MMC are calculated correctly, the calculation of the step is finished, and the state and the voltage and current values of the virtual diode of the step are stored for the next step calculation.
Optionally, according to the unblocking state of mixed type MMC, to the bridge arm full-bridge submodule piece live a viconam equivalence, confirm mixed type MMC full-bridge submodule piece live a viconam equivalent branch road, include: when the hybrid MMC is in an unlocking state, determining a thevenin equivalent branch of each bridge arm full-bridge submodule according to the state of the bridge arm full-bridge submodule; and serially overlapping the Thevenin equivalent branches of all bridge arm full-bridge submodules in the bridge arm to determine the Thevenin equivalent branches of the bridge arm full-bridge submodules.
Optionally, according to the unblocking state of mixed type MMC, to the bridge arm full-bridge submodule piece live a viconam equivalence, confirm mixed type MMC full-bridge submodule piece live a viconam equivalent branch road, still include: when the hybrid MMC is in a locked state, determining a charging voltage u according to the external voltage of the bridge arm full-bridge submodule and the equivalent capacitance of the bridge arm full-bridge submodulecharge(t); performing the calculation of this step, using the historyThe working state of the bridge arm full-bridge submodule of the step is judged in advance, the Thevenin branch of the bridge arm full-bridge submodule is determined according to the working state, and the equivalent resistance is determined
And equivalent voltage
After the calculation is finished, the port voltage u of the bridge arm full-bridge submodule is solved according to the voltage of each node of the MMCFBsm(t) and a charging voltage ucharge(t); judging whether the pre-judgment of the full-bridge submodule of each bridge arm is correct or not; when the pre-judgment of all bridge arm full-bridge submodules of the hybrid MMC is correct, the calculation in the step is completed, and the historical working state, the charging voltage and other variables of each bridge arm full-bridge submodule are stored for the next step of calculation.
Therefore, according to the hybrid MMC full-state efficient electromagnetic transient simulation method, the unlocking state and the locking state of the hybrid MMC can be simulated, high simulation precision is guaranteed, meanwhile, the calculation efficiency of the model is remarkably improved, and the method is more suitable for large-scale AC/DC power grid full-electromagnetic transient simulation analysis. The method is reasonable, efficient and more suitable for full electromagnetic simulation calculation of a large power grid.
According to another aspect of the present embodiment, there is provided a hybrid MMC full-state efficient electromagnetic transient simulation system 900, as shown in fig. 9, the system 900 including: a determining unlocking state module 910, configured to determine an unlocking state of the hybrid MMC according to an unlocking signal of the hybrid MMC, where the bridge arm submodule includes a bridge arm half-bridge submodule and a bridge arm full-bridge submodule; the half-bridge sub-module thevenin equivalent module 920 is used for carrying out thevenin equivalent on the bridge arm half-bridge sub-module according to the unlocking state of the mixed MMC to determine a thevenin equivalent branch of the mixed MMC half-bridge sub-module; the full-bridge sub-module thevenin equivalent module 930 is used for performing thevenin equivalent on the bridge arm full-bridge sub-module according to the unlocking state of the hybrid MMC to determine a thevenin equivalent branch of the hybrid MMC full-bridge sub-module; electromagnetic transient state simulation calculation module 940 is used for obtaining the hybrid MMC full-state high-efficiency model according to the hybrid MMC half-bridge submodule thevenin equivalent branch and the hybrid MMC full-bridge submodule thevenin equivalent branch, and performing electromagnetic transient state simulation calculation.
Optionally, the determine the unlock status module 910 includes: the sequencing algorithm determining submodule is used for determining a sequencing algorithm of the bridge arm submodule according to the unlocking state; the non-sequencing submodule is used for not sequencing the bridge arm submodule when the hybrid MMC is in a locking state; and the sequencing submodule is used for sequencing the bridge arm submodules according to the sequencing algorithm and the number N (t) of the conduction submodules output by the controller when the hybrid MMC is in the unlocking state, and determining the state of each submodule.
Optionally, the sorting sub-module comprises: a numbering unit for numbering the bridge arm sub-modules, wherein the total number of the bridge arm sub-modules is N, and the numbering of the half-bridge sub-modules is 1-NhNumber of full bridge submodule is Nh+1 to N; the pile determining unit is used for determining the scale of an initial pile, a pile sub-module and a pile outer sub-module according to the number N (t) of the conduction sub-modules, the number of the half-bridge sub-module and the number of the full-bridge sub-module; determining a top stack structure unit for the bridge arm current iarmThe direction and the number N (t) of the conducting sub-modules are used for determining the structure of the initial pile; the updating top stack structure unit is used for sequentially comparing the capacitor voltage pointed by the serial number of the sub-modules outside the stack with the capacitor voltage pointed by the serial number of the sub-modules at the root node at the top of the stack, determining a comparison result and updating the top stack structure of the initial stack according to the comparison result; and the state determining unit is used for determining the number of the bridge arm sub-modules to be input according to the updated top stack structure and the number N (t) of the conduction sub-modules, and determining the state of the bridge arm half-bridge sub-modules and the state of the bridge arm full-bridge sub-modules.
Optionally, a half-bridge sub-module thevenin equivalent module 920, comprising: determining a Thevenin equivalent branch submodule of each bridge arm half-bridge submodule, and determining the Thevenin equivalent branch of each bridge arm half-bridge submodule according to the state of the bridge arm half-bridge submodule when the hybrid MMC is in an unlocked state; and determining thevenin equivalent branch submodules of the bridge arm half-bridge submodules, and connecting and superposing thevenin equivalent branches of all the bridge arm half-bridge submodules in the bridge arm in series to determine the thevenin equivalent branches of the bridge arm half-bridge submodules.
Optionally, the half-bridge sub-module thevenin equivalent module 920 further includes: determining a first resistance voltage submodule for enabling the virtual diode model to be equivalent to a Thevenin branch based on the simulation step length and the integral algorithm of the step when the hybrid MMC is in a locked state, and determining the equivalent resistance of the virtual diode model
And equivalent voltage of the virtual diode model
Solving a second resistance voltage submodule for equivalent series connection of all bridge arm half-bridge submodule capacitors in a bridge arm into a Thevenin branch, and according to the equivalent resistance
And equivalent voltage
Equivalent resistance of bridge arm half-bridge submodule wearing Winan model
And equivalent voltage
The port voltage and current solving submodule is used for solving the port voltage and current of the virtual diode model according to the voltage of each node of the MMC after the calculation is finished; the storage diode submodule is used for judging whether the calculation of each virtual diode model is correct or not according to the current step state and the previous step state; and when all the virtual diode models of the hybrid MMC are calculated correctly, the calculation of the step is finished, and the state and the voltage and current values of the virtual diode of the step are stored for the next step calculation.
Optionally, a full-bridge sub-module thevenin equivalent module 930, comprising: determining a Thevenin equivalent branch submodule of each bridge arm full-bridge submodule, and determining the Thevenin equivalent branch of each bridge arm full-bridge submodule according to the state of the bridge arm full-bridge submodule when the hybrid MMC is in an unlocked state; and determining thevenin equivalent branch submodules of the bridge arm full-bridge submodules, and connecting and superposing thevenin equivalent branches of all the bridge arm full-bridge submodules in the bridge arm in series to determine the thevenin equivalent branches of the bridge arm full-bridge submodules.
Optionally, the full-bridge sub-module thevenin equivalent module 930 further comprises: the charging voltage determining submodule is used for determining a charging voltage u according to the external voltage of the bridge arm full-bridge submodule and the equivalent capacitance voltage of the bridge arm full-bridge submodule when the hybrid MMC is in a locked statecharge(t); determining a third resistance voltage submodule, performing calculation in the step, adopting a historical state to pre-judge the working state of the bridge arm full-bridge submodule in the step, determining the Thevenin branch of the bridge arm full-bridge submodule according to the working state, and determining the equivalent resistance
And equivalent voltage
A voltage solving submodule used for solving the port voltage u of the bridge arm full-bridge submodule according to the voltage of each node of the MMC after the calculation is finishedFBsm(t) and a charging voltage ucharge(t); the judgment interpolation submodule is used for judging whether the prejudgment of the full-bridge submodule of each bridge arm is correct or not; and the variable storage submodule is used for completing the calculation in the step when the prejudgment of all the bridge arm full-bridge submodules of the hybrid MMC is correct, storing the variable of each bridge arm full-bridge submodule for the next step of calculation, and the variable comprises the historical working state and the charging voltage.
The hybrid MMC full-state efficient electromagnetic transient simulation system 900 according to the embodiment of the present invention corresponds to the hybrid MMC full-state efficient electromagnetic transient simulation method 100 according to another embodiment of the present invention, and is not described herein again.
As will be appreciated by one skilled in the art, embodiments of the present application may be provided as a method, system, or computer program product. Accordingly, the present application may take the form of an entirely hardware embodiment, an entirely software embodiment or an embodiment combining software and hardware aspects. Furthermore, the present application may take the form of a computer program product embodied on one or more computer-usable storage media (including, but not limited to, disk storage, CD-ROM, optical storage, and the like) having computer-usable program code embodied therein. The scheme in the embodiment of the application can be implemented by adopting various computer languages, such as object-oriented programming language Java and transliterated scripting language JavaScript.
The present application is described with reference to flowchart illustrations and/or block diagrams of methods, apparatus (systems), and computer program products according to embodiments of the application. It will be understood that each flow and/or block of the flow diagrams and/or block diagrams, and combinations of flows and/or blocks in the flow diagrams and/or block diagrams, can be implemented by computer program instructions. These computer program instructions may be provided to a processor of a general purpose computer, special purpose computer, embedded processor, or other programmable data processing apparatus to produce a machine, such that the instructions, which execute via the processor of the computer or other programmable data processing apparatus, create means for implementing the functions specified in the flowchart flow or flows and/or block diagram block or blocks.
These computer program instructions may also be stored in a computer-readable memory that can direct a computer or other programmable data processing apparatus to function in a particular manner, such that the instructions stored in the computer-readable memory produce an article of manufacture including instruction means which implement the function specified in the flowchart flow or flows and/or block diagram block or blocks.
These computer program instructions may also be loaded onto a computer or other programmable data processing apparatus to cause a series of operational steps to be performed on the computer or other programmable apparatus to produce a computer implemented process such that the instructions which execute on the computer or other programmable apparatus provide steps for implementing the functions specified in the flowchart flow or flows and/or block diagram block or blocks.
While the preferred embodiments of the present application have been described, additional variations and modifications in those embodiments may occur to those skilled in the art once they learn of the basic inventive concepts. Therefore, it is intended that the appended claims be interpreted as including preferred embodiments and all alterations and modifications as fall within the scope of the application.
It will be apparent to those skilled in the art that various changes and modifications may be made in the present application without departing from the spirit and scope of the application. Thus, if such modifications and variations of the present application fall within the scope of the claims of the present application and their equivalents, the present application is intended to include such modifications and variations as well.
Claims (14)
1. A hybrid MMC full-state efficient electromagnetic transient simulation method is characterized by comprising the following steps:
judging the unlocking state of the hybrid MMC according to the unlocking signal of the hybrid MMC, wherein the bridge arm submodule comprises a bridge arm half-bridge submodule and a bridge arm full-bridge submodule;
according to the unlocking state of the mixed MMC, thevenin equivalence is carried out on the bridge arm half-bridge submodule, and a thevenin equivalent branch of the mixed MMC half-bridge submodule is determined;
according to the unlocking state of the hybrid MMC, thevenin equivalence is carried out on the bridge arm full-bridge submodule, and a thevenin equivalent branch of the hybrid MMC full-bridge submodule is determined;
according to mixed type MMC half-bridge submodule thevenin equivalent branch with mixed type MMC full-bridge submodule thevenin equivalent branch, obtain mixed type MMC full-state high efficiency model, carry out electromagnetic transient state simulation calculation.
2. The method of claim 1, wherein determining the unblocking state of the hybrid MMC according to an unblocking signal of the hybrid MMC comprises:
determining a sorting algorithm of the bridge arm sub-modules according to the unlocking state;
when the hybrid MMC is in a locking state, the bridge arm sub-modules are not sequenced;
and when the hybrid MMC is in an unlocking state, sequencing the bridge arm sub-modules according to the sequencing algorithm and the number N (t) of the conduction sub-modules output by the controller, and determining the state of each sub-module.
3. The method of claim 2, wherein when the hybrid MMC is in an unlocked state, the bridge arm sub-modules are sorted according to the number of conducting sub-modules output by the controller, and determining the state of each sub-module comprises:
numbering the bridge arm sub-modules, wherein the total number of the bridge arm sub-modules is N, and the numbering of the half-bridge sub-modules is 1-NhNumber of full bridge submodule is Nh+1～N；
Determining the scale of an initial stack, a stack neutron module and a stack outer submodule according to the number N (t) of the conduction submodule, the number of the half-bridge submodule and the number of the full-bridge submodule;
according to bridge arm current iarmThe direction and the number N (t) of the conducting sub-modules are used for determining the structure of the initial pile;
comparing the capacitor voltage pointed by the serial number of the sub-module outside the pile with the capacitor voltage pointed by the serial number of the sub-module at the root node at the top of the pile in sequence, determining a comparison result, and updating the structure of the initial pile according to the comparison result;
and determining the number of the bridge arm sub-modules to be input and determining the states of the bridge arm half-bridge sub-modules and the bridge arm full-bridge sub-modules according to the updated structure and the number N (t) of the conduction sub-modules.
4. The method of claim 1, wherein thevenin equivalence is performed on the bridge arm half-bridge sub-module according to the unlocking state of the hybrid MMC, and determining a thevenin equivalent branch of the hybrid MMC half-bridge sub-module comprises:
when the hybrid MMC is in an unlocking state, determining a thevenin equivalent branch of each bridge arm half-bridge submodule according to the state of the bridge arm half-bridge submodule;
and (4) serially overlapping the Thevenin equivalent branches of all the half-bridge sub-modules in the bridge arm to determine the Thevenin equivalent branches of the half-bridge sub-modules of the bridge arm.
5. The method of claim 1, wherein thevenin equivalence is performed on the bridge arm half-bridge sub-module according to the unlocking state of the hybrid MMC, and a thevenin equivalent branch of the hybrid MMC half-bridge sub-module is determined, further comprising:
when the hybrid MMC is in a locked state, the virtual diode model is equivalent to a Thevenin branch circuit based on the simulation step length and the integral algorithm of the step, and the equivalent resistance of the virtual diode model is determined
And equivalent voltage of the virtual diode model
According to equivalent resistance
And equivalent voltage
All half-bridge sub-modules in the bridge arm are equivalent to thevenin branch circuits in a capacitance series connection mode, and solution is carried out
And
all bridge arm half-bridge sub-modules in the bridge arm are equivalent to thevenin branch circuits in series connection through capacitors, and the equivalent resistors are used for
And equivalent voltage
Equivalent resistance of bridge arm half-bridge submodule wearing Winan model
And equivalent voltage
After the calculation is finished, solving the voltage and current of the virtual diode model port according to the voltage of each node of the MMC;
judging whether the calculation of each virtual diode model is correct or not according to the current step state and the previous step state; and when all the virtual diode models of the hybrid MMC are calculated correctly, the calculation of the step is finished, and the state and the voltage and current values of the virtual diode of the step are stored for the next step calculation.
6. The method according to claim 1, wherein thevenin equivalence is performed on the bridge arm full-bridge sub-module according to the unlocking state of the hybrid MMC, and the determination of the thevenin equivalent branch of the hybrid MMC full-bridge sub-module comprises the following steps:
when the hybrid MMC is in an unlocking state, determining a thevenin equivalent branch of each bridge arm full-bridge submodule according to the state of the bridge arm full-bridge submodule;
and serially overlapping the Thevenin equivalent branches of all the full-bridge submodules in the bridge arm to determine the Thevenin equivalent branches of the full-bridge submodules of the bridge arm.
7. The method according to claim 1, wherein thevenin equivalence is performed on the bridge arm full-bridge sub-module according to the unlocking state of the hybrid MMC, and a thevenin equivalent branch of the hybrid MMC full-bridge sub-module is determined, further comprising:
when the hybrid MMC is in a locked stateIn a state, determining a charging voltage u according to the external voltage of the bridge arm full-bridge submodule and the equivalent capacitance voltage of the bridge arm full-bridge submodulecharge(t)；
Performing calculation, adopting historical state to prejudge the working state of the bridge arm full-bridge submodule of the step, determining the Thevenin branch of the bridge arm full-bridge submodule according to the working state, and determining the equivalent resistance
And equivalent voltage
After the calculation is finished, the port voltage u of the bridge arm full-bridge submodule is solved according to the voltage of each node of the MMCFBsm(t) and a charging voltage ucharge(t)；
Judging whether the pre-judgment of the full-bridge submodule of each bridge arm is correct or not;
when the pre-judgment of all bridge arm full-bridge submodules of the hybrid MMC is correct, the calculation in the step is completed, and the historical working state, the charging voltage and other variables of each bridge arm full-bridge submodule are stored for the next step of calculation.
8. The utility model provides a high-efficient electromagnetism transient state simulation system of mixed type MMC full state which characterized in that includes:
the unlocking state judging module is used for judging the unlocking state of the hybrid MMC according to an unlocking signal of the hybrid MMC, and the bridge arm submodule comprises a bridge arm half-bridge submodule and a bridge arm full-bridge submodule;
the half-bridge sub-module Thevenin equivalent module is used for carrying out Thevenin equivalent on the bridge arm half-bridge sub-module according to the unlocking state of the mixed MMC to determine a Thevenin equivalent branch of the mixed MMC half-bridge sub-module;
the full-bridge sub-module Thevenin equivalent module is used for carrying out Thevenin equivalent on the bridge arm full-bridge sub-module according to the unlocking state of the hybrid MMC to determine a Thevenin equivalent branch of the hybrid MMC full-bridge sub-module;
and the electromagnetic transient simulation calculation module is used for obtaining a hybrid MMC full-state efficient model according to the hybrid MMC half-bridge submodule Thevenin equivalent branch and the hybrid MMC full-bridge submodule Thevenin equivalent branch, and performing electromagnetic transient simulation calculation.
9. The system of claim 8, wherein the determine an unlocked state module comprises:
the sequencing algorithm determining submodule is used for determining a sequencing algorithm of the bridge arm submodule according to the unlocking state;
the non-sequencing submodule is used for not sequencing the bridge arm submodule when the hybrid MMC is in a locking state;
and the sequencing submodule is used for sequencing the bridge arm submodules according to the sequencing algorithm and the number N (t) of the conduction submodules output by the controller when the hybrid MMC is in the unlocking state, and determining the state of each submodule.
10. The system of claim 8, wherein the ordering sub-module comprises:
a numbering unit for numbering the bridge arm sub-modules, wherein the total number of the bridge arm sub-modules is N, and the numbering of the half-bridge sub-modules is 1-NhNumber of full bridge submodule is Nh+1～N；
The pile determining unit is used for determining the scale of an initial pile, a pile sub-module and a pile outer sub-module according to the number N (t) of the conduction sub-modules, the number of the half-bridge sub-module and the number of the full-bridge sub-module;
determining a top stack structure unit for the bridge arm current iarmThe direction and the number N (t) of the conducting sub-modules are used for determining the top stack structure of the initial stack;
the updating top stack structure unit is used for sequentially comparing the capacitor voltage pointed by the serial number of the sub-modules outside the stack with the capacitor voltage pointed by the serial number of the sub-modules at the root node at the top of the stack, determining a comparison result and updating the structure of the initial stack according to the comparison result;
and the state determining unit is used for determining the number of the bridge arm sub-modules to be input according to the updated top stack structure and the number N (t) of the conduction sub-modules, and determining the state of the bridge arm half-bridge sub-modules and the state of the bridge arm full-bridge sub-modules.
11. The system of claim 8, wherein the half-bridge sub-module thevenin equivalent module comprises:
determining a Thevenin equivalent branch submodule of each half-bridge submodule, and determining the Thevenin equivalent branch of each half-bridge submodule according to the state of the bridge arm half-bridge submodule when the hybrid MMC is in an unlocked state;
and determining thevenin equivalent branch submodules of the bridge arm half-bridge submodules, and connecting and superposing thevenin equivalent branches of all the half-bridge submodules in the bridge arm in series to determine the thevenin equivalent branches of the bridge arm half-bridge submodules.
12. The system of claim 8, wherein the half-bridge sub-module thevenin equivalent module further comprises:
determining a first resistance voltage submodule for enabling the virtual diode model to be equivalent to a Thevenin branch based on the simulation step length and the integral algorithm of the step when the hybrid MMC is in a locked state, and determining the equivalent resistance of the virtual diode model
And equivalent voltage of the virtual diode model
Solving a second resistance voltage submodule for equivalent series connection of all bridge arm half-bridge submodule capacitors in a bridge arm into a Thevenin branch, and according to the equivalent resistance
And equivalent voltage
Equivalent resistance of bridge arm half-bridge submodule wearing Winan model
And equivalent voltage
The port voltage and current solving submodule is used for solving the port voltage and current of the virtual diode model according to the voltage of each node of the MMC after the calculation is finished;
the storage diode submodule is used for judging whether the calculation of each virtual diode model is correct or not according to the current step state and the previous step state; and when all the virtual diode models of the hybrid MMC are calculated correctly, the calculation of the step is finished, and the state and the voltage and current values of the virtual diode of the step are stored for the next step calculation.
13. The system of claim 8, wherein the full-bridge sub-module thevenin equivalent module comprises:
determining a Thevenin equivalent branch submodule of each full-bridge submodule, and determining the Thevenin equivalent branch of each full-bridge submodule according to the state of the full-bridge submodule when the hybrid MMC is in an unlocked state;
and determining thevenin equivalent branch submodules of the bridge arm full-bridge submodules, and connecting and superposing the thevenin equivalent branches of all the full-bridge submodules in the bridge arm in series to determine the thevenin equivalent branches of the bridge arm full-bridge submodules.
14. The system of claim 8, wherein the full-bridge sub-module thevenin equivalent module further comprises:
the charging voltage determining submodule is used for determining a charging voltage u according to the external voltage of the bridge arm full-bridge submodule and the equivalent capacitance voltage of the bridge arm full-bridge submodule when the hybrid MMC is in a locked statecharge(t)；
Determining a third resistance voltage submodule, performing calculation in the step, adopting a historical state to pre-judge the working state of the bridge arm full-bridge submodule in the step, determining the Thevenin branch of the bridge arm full-bridge submodule according to the working state, and determining the equivalent resistance
And equivalent voltage
A voltage solving submodule used for solving the port voltage u of the bridge arm full-bridge submodule according to the voltage of each node of the MMC after the calculation is finishedFBsm(t) and a charging voltage ucharge(t)；
The judgment interpolation submodule is used for judging whether the prejudgment of the full-bridge submodule of each bridge arm is correct or not;
and the variable storage submodule is used for completing the calculation in the step when the prejudgment of all the bridge arm full-bridge submodules of the hybrid MMC is correct, storing the variable of each bridge arm full-bridge submodule for the next step of calculation, and the variable comprises the historical working state and the charging voltage.
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Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
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| CN115021536A (en) * | 2022-07-21 | 2022-09-06 | 南方电网科学研究院有限责任公司 | Voltage control method and device for bridge arm unit model |
| CN116613961A (en) * | 2023-05-25 | 2023-08-18 | 国网江苏省电力有限公司电力科学研究院 | Mixed MMC simulation model and method for simulating locking state of bridge arm |
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Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN115021536A (en) * | 2022-07-21 | 2022-09-06 | 南方电网科学研究院有限责任公司 | Voltage control method and device for bridge arm unit model |
| CN116613961A (en) * | 2023-05-25 | 2023-08-18 | 国网江苏省电力有限公司电力科学研究院 | Mixed MMC simulation model and method for simulating locking state of bridge arm |
| CN116613961B (en) * | 2023-05-25 | 2024-01-30 | 国网江苏省电力有限公司电力科学研究院 | Mixed MMC simulation model and method for simulating locking state of bridge arm |
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