CN113746108A - T-type three-level SAPF open circuit fault sequence model prediction fault-tolerant control method - Google Patents

T-type three-level SAPF open circuit fault sequence model prediction fault-tolerant control method Download PDF

Info

Publication number
CN113746108A
CN113746108A CN202110922578.2A CN202110922578A CN113746108A CN 113746108 A CN113746108 A CN 113746108A CN 202110922578 A CN202110922578 A CN 202110922578A CN 113746108 A CN113746108 A CN 113746108A
Authority
CN
China
Prior art keywords
fault
sapf
current
voltage
tolerant control
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Granted
Application number
CN202110922578.2A
Other languages
Chinese (zh)
Other versions
CN113746108B (en
Inventor
龙波
曹天旭
沈大为
朱诗涵
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
University of Electronic Science and Technology of China
Guangdong Electronic Information Engineering Research Institute of UESTC
Original Assignee
University of Electronic Science and Technology of China
Guangdong Electronic Information Engineering Research Institute of UESTC
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by University of Electronic Science and Technology of China, Guangdong Electronic Information Engineering Research Institute of UESTC filed Critical University of Electronic Science and Technology of China
Priority to CN202110922578.2A priority Critical patent/CN113746108B/en
Publication of CN113746108A publication Critical patent/CN113746108A/en
Application granted granted Critical
Publication of CN113746108B publication Critical patent/CN113746108B/en
Active legal-status Critical Current
Anticipated expiration legal-status Critical

Links

Images

Classifications

    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
    • H02J3/00—Circuit arrangements for ac mains or ac distribution networks
    • H02J3/18—Arrangements for adjusting, eliminating or compensating reactive power in networks
    • H02J3/1821—Arrangements for adjusting, eliminating or compensating reactive power in networks using shunt compensators
    • H02J3/1835—Arrangements for adjusting, eliminating or compensating reactive power in networks using shunt compensators with stepless control
    • H02J3/1842—Arrangements for adjusting, eliminating or compensating reactive power in networks using shunt compensators with stepless control wherein at least one reactive element is actively controlled by a bridge converter, e.g. active filters
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02M—APPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF
    • H02M1/00—Details of apparatus for conversion
    • H02M1/32—Means for protecting converters other than automatic disconnection
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02M—APPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF
    • H02M7/00—Conversion of ac power input into dc power output; Conversion of dc power input into ac power output
    • H02M7/42—Conversion of dc power input into ac power output without possibility of reversal
    • H02M7/44—Conversion of dc power input into ac power output without possibility of reversal by static converters
    • H02M7/48—Conversion of dc power input into ac power output without possibility of reversal by static converters using discharge tubes with control electrode or semiconductor devices with control electrode
    • H02M7/483—Converters with outputs that each can have more than two voltages levels
    • H02M7/487—Neutral point clamped inverters
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
    • Y02E40/00—Technologies for an efficient electrical power generation, transmission or distribution
    • Y02E40/20—Active power filtering [APF]

Landscapes

  • Engineering & Computer Science (AREA)
  • Power Engineering (AREA)
  • Inverter Devices (AREA)

Abstract

In order to solve the problem of fault-tolerant control of the T-type three-level LCL-type SAPF when a horizontal bridge arm or a vertical bridge arm has a fault, the invention adopts a sequence model to predict the fault-tolerant control. Dividing the SAPF under fault operation into a healthy state, a horizontal unhealthy state and a vertical unhealthy state, and selecting different direct-current bus voltage reference values and alternative vectors according to the three states; through ip‑iqThe method extracts harmonic current of a nonlinear load as a reference value output by SAPF, and controls DC bus voltage by PI controller; two cost functions of firstly controlling the midpoint voltage and then controlling the compensation current are designed and are in cascade operation, so that the SAPF under the fault can obtain excellent current compensation effect under three different states of operation, the stability of the direct-current bus voltage and the midpoint voltage is ensured, and the active power factor is improvedReliability of the power filter system.

Description

T-type three-level SAPF open circuit fault sequence model prediction fault-tolerant control method
Technical Field
The invention belongs to the technical field of power electronic converter fault control, and particularly relates to a T-type three-level SAPF fault-tolerant control method based on sequence model predictive control.
Background
With the great input of the nonlinear load, a great amount of harmonic waves exist when the power grid is injected, the power quality is reduced, and negative effects are caused on electric equipment. The parallel Active Power Filter (SAPF) cancels the reactive current or harmonic current of the nonlinear load through the Power electronic technology, so that the harmonic component of the Power grid is obviously reduced, and the parallel Active Power Filter is widely applied. Meanwhile, compared with the traditional two-level topology, the T-type three-level power electronic topology can enable the SAPF to output better compensation current, so that the total harmonic distortion of a power grid is small, and the harmonic management function of the SAPF is improved.
In recent years, in order to solve the reliability problem of a power electronic system, the power electronic system under a fault has the capability of normally operating, and the fault-tolerant control problem of a power converter is a research hotspot. During the operation of the SAPF based on the T-type three-level topology, an open-circuit fault may occur in a certain switching device due to thermal cycling and gate driving errors, and the switching device may be considered to be always in an off state. This can cause the compensation current output by the SAPF to be severely distorted, so that the harmonic component of the current of the power grid is remarkably increased; it also causes the dc side capacitance voltage of the SAPF to fluctuate or be unbalanced.
The T-shaped three-level switch device can be divided into a horizontal bridge arm and a vertical bridge arm, wherein the severity of the fault of the horizontal bridge arm is far less than that of the fault of the vertical bridge arm. The reason is that the horizontal bridge arm does not affect the space vector modulation range of the topology, while the vertical bridge arm fault reduces the vector modulation range by one half. Therefore, the existing fault-tolerant control proposes two types of methods for pertinence: firstly, a redundant device is added in the inverter, when a switch fails, the redundant circuit takes over a fault circuit, and the new topology is ensured to have a sufficient modulation range; and secondly, changing a modulation algorithm, improving the reference value of the voltage at the direct current side, and changing an algorithm of a Space Vector Pulse Width Modulation (SVPWM) mode to enable each output vector to be in a modulation range.
However, the above two methods also have their own disadvantages: the redundant device method adds extra components such as IGBT, relay and thyristor, which is not economical and the system is heavy; the SVPWM-based modulation algorithm is complex in that the duration of each resultant vector is recalculated at each sampling time.
At present, in the fault-tolerant control of the SAPF, the application of the model predictive control of a limited control set is not available. Compared with the traditional control method, the model prediction control does not need PWM modulation, but outputs an optimal switching sequence at each sampling moment according to the solution of the optimization problem; meanwhile, model predictive control is also suitable for solving the problem of multiple optimization targets such as SAPF fault-tolerant control.
Disclosure of Invention
The technical problem to be solved by the invention is as follows: in order to realize fault-tolerant operation when any one of the switching devices of the T-type three-level LCL-type SAPF horizontal bridge arm and the vertical bridge arm has an open-circuit fault, a fault-tolerant control method based on sequence model predictive control is provided.
In order to achieve the above object, the present invention adopts the following technical solutions.
According to the topology diagram shown in fig. 1, a three-phase alternating voltage v is detected by a voltage sensor and a current sensorgThree-phase SAPF output current i2Three-phase current i of non-linear loadlAnd the voltage u of two capacitors on the DC bus sidepAnd un. And estimating the side current i of the three-phase inverter by a Kalman filter1And three-phase filter capacitor voltage vC。
According to the control block diagram shown in fig. 2, reactive current and active harmonic current to be compensated for SAPF are extracted. Firstly, phase information of a power grid is obtained through a phase-locked loop (PLL), three-phase load current is converted into a two-phase static coordinate system through Clark conversion and is converted into a two-phase rotating coordinate system through Park conversion, and because the phase of a d axis is consistent with that of the power grid, a d axis component ildIs an active current, q-axis component
Figure BDA0003207991640000027
Is a reactive current; then passes through a low pass filter(LPF) obtaining fundamental wave components of active current and reactive current, and then obtaining fundamental wave components of the three-phase load current through Park inverse transformation and Clark inverse transformation; finally, the load current is used for subtracting the fundamental component to obtain the harmonic component needing compensation of the SAPF, namely the reference compensation current of the SAPF
Figure BDA0003207991640000026
If the compensated current is ensured to be in the same phase with the power grid, the reactive current switch can be disconnected, and only the active current is output.
The control block diagram in fig. 2 further includes a dc voltage control module, which is implemented by PI control of an error of the dc voltage, and an error current output by the PI control is injected into an active fundamental current of the d-axis, which together form a reference compensation current of the SAPF. The transfer function of the PI controller is:
Figure BDA0003207991640000021
wherein, KpIs a proportionality coefficient, KiIs an integral coefficient.
The T-type three-level SAPF faults can be divided into a horizontal bridge arm fault and a vertical bridge arm fault. When the horizontal bridge arm has a fault, the running state can be divided into a healthy state and a horizontal unhealthy state according to different current directions of the inverter side; when the vertical bridge arm has a fault, the running state can be divided into a healthy state and a vertical unhealthy state according to different current directions of the inverter side. The SAPF in the healthy state is not affected by the fault, while the compensation current and the midpoint voltage of the SAPF in the unhealthy state are affected to different degrees.
According to different properties of the three states, the minimum direct-current voltage reference value required for ensuring the modulation range can be obtained through phasor analysis of the LCL filter circuit and space vector diagrams of the three-state circuit
Figure BDA0003207991640000028
The empirical formula is as follows:
Figure BDA0003207991640000022
wherein the content of the first and second substances,
Figure BDA0003207991640000023
and outputting the maximum value of the modulus of the reference voltage vector in one power frequency period for the inverter.
Figure BDA0003207991640000024
Will be used in the PI control loop in fig. 2.
The sequence model predicts two goals for fault-tolerant control: balancing of midpoint voltage, compensating current with respect to its reference value
Figure BDA0003207991640000025
The tracking of (2). Define the midpoint voltage as unAnd upThe difference between the two capacitors of the dc bus should be kept as small as possible to keep the midpoint voltage equal to 0 in order to ensure that the two capacitors of the dc bus always share the voltage of the dc power supply.
Firstly, in order to realize the control of the midpoint voltage balance, a cost function is designed, and the cost function formula is as follows:
J1＝|(Ts/C1)|u(k)|Ti1(k)+un(k)-up(k) i type III
Wherein T issTo sample time, C1The upper direct current bus capacitance value u (k) is a variable of the cost function. u (k) will vary depending on the three operating conditions. Since u (k) in equation three has an absolute value, | u (k) | can be used as a variable, and all possible cases can be substituted into J1The magnitudes are sorted to obtain n optimal switching vectors, which are recorded as
Figure BDA0003207991640000031
Secondly, in order to realize the control of the SAPF compensation current, a cost function is designed, and the cost function formula is as follows:
J2＝||C(Axαβ(k)+Bu(k)+Tvg(k)-xαβref(k +1)) | | formula four
Wherein | | | represents a vector 2-norm; x is the number ofαβ(k)＝[i1α(k),i1β(k),i2α(k),i2β(k),vCα(k),vCβ(k)]TThe state vector is formed by combining inverter side current, SAPF compensation current and filter capacitor voltage after Clark conversion; x is the number ofαβref(k +1) is a predicted value of the state vector reference value. The prediction of the reference value can be realized by a Lagrange extrapolation method and a phase-locked loop; A. b, C, T is a constant matrix, which is only related to the inverter parameters.
Due to J1To find n optimal switching vectors containing absolute values, it is necessary to assign | uopt(k) Absolute value of | is removed to obtain a plurality of J2According to the different sum | u of the SAPF operating statesopt(k) And if the | is different, the obtained alternative vectors are also different.
Finally, a plurality of switch vectors are substituted into a cost function J1In (1), calculating1Minimum switching vector, denoted as uopt(k) In that respect The switching vector is converted into an on-off signal of the T-type three-level SAPF switching element and is sent in at the next sampling moment.
The flow chart of the sequence model predictive fault-tolerant control is shown in fig. 3, two cost functions form a cascaded control sequence, and two alternative vectors with different cost functions are selected according to different running states of the SAPF.
The traditional model prediction control is to J1And J2And combining the weights, wherein the cost function is as follows:
J0＝||C(Axαβ(k)+Bu(k)+Tvg(k)-xαβref(k+1))||+λnp|(Ts/C1)|u(k)|Ti1(k)+un(k)-up(k) equation five
Wherein λnpIs a weighting factor. Because the running performances of the health state, the horizontal non-health state and the vertical non-health state are different, three different weight factors need to be selected. Trial and error with weight factor requiring repetitionSelection is a disadvantage of conventional model predictive control. The invention relates to a cost function J of multiple targets0Conversion into two concatenated cost functions J1And J2And the selection of the weight factor is avoided.
The overall system block diagram of the present invention is shown in fig. 4, wherein the SAPF reference compensation current calculation module refers to the control block diagram of fig. 2. After the working state of the system is determined, the absolute value of the required candidate vector and the reference value of the direct current bus voltage can be calculated correspondingly. Wherein, the reference value of the DC bus voltage
Figure BDA0003207991640000032
Will be used in the compensation current reference value calculation module and the absolute value of the alternative vector will be used to calculate the cost function J1. Two cost functions J1And J2Forming a cascade control sequence, firstly controlling the midpoint voltage, then controlling the compensation current, and finally, controlling the optimal switching vector uopt(k) And the switching signals required by the switching device of the T-shaped three-level converter are converted, and the feedback control with the fault-tolerant function is completed.
Due to the application of the technical scheme, the invention has the following characteristics:
1. the invention adopts a model predictive control technology, does not need PWM modulation, can ensure that T-shaped three-level SAPF keeps fault-tolerant operation when any switching element fails, and ensures the quality of a power grid, the balance of midpoint voltage and the stability of direct-current voltage;
2. the invention adopts a sequence model predictive control technology, and avoids the selection of weight factors compared with the traditional model predictive control;
3. according to the invention, the fault operation states are divided into a healthy state, a horizontal unhealthy state and a vertical unhealthy state, different control parameters are distributed to the three states, and the control efficiency is improved.
Drawings
FIG. 1: the T-type three-level LCL-type SAPF topological structure chart is disclosed;
FIG. 2: generating a control block diagram of SAPF reference compensation current and DC voltage control;
FIG. 3: the invention discloses a flow chart of sequence model prediction fault-tolerant control;
FIG. 4: the invention discloses a system block diagram of sequence model prediction fault-tolerant control;
FIG. 5: the non-linear load circuit diagram in the invention;
FIG. 6: the invention relates to an experimental oscillogram when no fault occurs, wherein (a) is A-phase load current and SAPF compensation current, (b) is A-phase grid current and grid voltage, (c) is THD of the A-phase grid current, and (d) is direct-current bus voltage and midpoint voltage;
FIG. 7: after a horizontal bridge arm fault occurs, the fault-tolerant control strategy is put into experimental oscillograms before and after the fault-tolerant control strategy is put into use, wherein (a) is three-phase power grid current, and (b) is direct-current bus voltage, midpoint voltage and A-phase inverter output voltage.
FIG. 8: after a vertical bridge arm fault occurs, the fault-tolerant control strategy is put into experimental oscillograms before and after the fault-tolerant control strategy is put into use, wherein (a) is three-phase power grid current, and (b) is direct-current bus voltage, midpoint voltage and A-phase inverter output voltage.
Detailed Description
The technical solution will be described clearly and completely with reference to the preferred examples of the present invention and the accompanying drawings. It should be understood that the preferred examples are intended to illustrate the invention only and are not intended to limit the scope of the invention. Based on the embodiments of the present invention, those skilled in the art can obtain all other embodiments without creative efforts, which belong to the protection scope of the present invention.
The invention provides a fault-tolerant control strategy for T-type three-level SAPF open circuit fault. The working state of the SAPF is distinguished by judging the direction of the current on the side of the inverter, and different control parameters are calculated; the sequence model predictive control is realized by two cost functions. The overall scheme can ensure that the SAPF can still ensure the balance of the midpoint voltage and the high-quality compensation current under the condition of the open-circuit fault of a single switching device, and the reliability of the system is improved.
The control block diagram of an embodiment is shown in fig. 4, and the main content of this embodiment includes the following stepsProcedure (with S)a3Open circuit fault representing horizontal bridge arm fault, Sa1Open circuit fault represents vertical leg fault):
step S1: three-phase alternating voltage v for collecting T-type three-level LCL (lower control limit) SAPF (ground fault power factor) through voltage sensor and current sensorgThree-phase network side current i2Three-phase non-linear load current ilVoltage u of two capacitors at DC bus sidepAnd un。
Step S2: estimation of three-phase inverter side current i by means of a Kalman filter1And three-phase filter capacitor voltage vC。
Step S3: if S isa3Open-circuit fault, determining the A-phase inverter side current i1aIf the flow direction is negative, the state is judged to be a horizontal unhealthy state; if the positive direction is adopted, the health state is judged; if S isa1Open-circuit fault, determining the A-phase inverter side current i1aIf the flow direction is positive, the state is judged to be vertical unhealthy state; if the positive direction is adopted, the health state is judged;
step S4: obtaining A-phase grid voltage v by means of a phase-locked loopgaTo determine a three-phase network-side current reference value i therefrom2ref. Reversely deducing a reference value i of the current at the side of the inverter through the circuit relation of the LCL type grid-connected inverter1refReference value v of the filter capacitor voltageCrefInverter output reference voltage vector
Figure BDA0003207991640000051
And converting the two-phase static coordinate system into a two-phase static coordinate system through Clark transformation.
Step S5: calculating the reference value of the DC bus voltage
Figure BDA0003207991640000052
The empirical formula is as follows:
Figure BDA0003207991640000053
wherein the content of the first and second substances,
Figure BDA0003207991640000054
and outputting the maximum value of the modulus of the reference voltage vector in one power frequency period for the inverter. Accordingly, the direct current voltage reference value of the healthy state or the horizontal unhealthy state is 800V, and the direct current voltage reference value of the vertical unhealthy state is 1200V.
Step S6: calculating a reference offset current for the SAPF according to the control block diagram of FIG. 2
Figure BDA0003207991640000055
Wherein, the one obtained in step S5
Figure BDA0003207991640000056
Will be substituted into a PI controller that controls the dc voltage. The transfer function of the PI controller is:
Figure BDA0003207991640000057
wherein, KpIs a proportionality coefficient, KiIs an integral coefficient.
Step S7: combined state vector xαβ(k)＝[i1α(k),i1β(k),i2α(k),i2β(k),vCα(k),vCβ(k)]T，xαβref(k) The same is true. X is to beαβref(k) Linear extrapolation is carried out by second-order Lagrange extrapolation method to obtain predicted value xαβref(k+1)。
Step S8: step S721: substituting the possible situation of absolute value | u (k) | of the candidate vector in three working states (see table 1 for details) into the cost function J1In screening out1Minimum n optimal solutions
Figure BDA0003207991640000058
n is 4 in a healthy state, 2 in a horizontal unhealthy state and 7 in a vertical unhealthy state. The cost function is as follows:
J1＝|(Ts/C1)|u(k)|Ti1(k)+un(k)-up(k) i type III
Wherein T issTo sample time, C1Is the capacitance value of the upper direct current bus.
TABLE 1J for three operating conditions1Possible cases of the absolute value of the candidate vector:
working state Cost function J1Possible cases of the absolute value of the candidate vector
State of health OOO,OOP,OPO,OPP,POO,POP,PPO,PPP
Horizontal non-health state POO,POP,PPO,PPP
Vertical unhealthy state OOO,OOP,OPO,OPP,POO,POP,PPO,PPP
P in table 1 represents a high level and O represents a zero level.
Step S9: will J1All n optimal solutions are combined into a cost function J by removing absolute values2The candidate vector of (2). The results of removing the absolute value are different depending on the operation state, and the results of removing the absolute value are shown in tables 3, 4, and 5.
Table 3 is the result of the state of health minus the absolute value of the optimal solution:
Figure BDA0003207991640000061
table 4 is the result of removing the absolute value of the optimal solution for horizontal unhealthy conditions:
Figure BDA0003207991640000062
table 5 is the result of removing the absolute value of the optimal solution for vertical unhealthy conditions:
Figure BDA0003207991640000063
in tables 3, 4, and 5, P represents high level, O represents zero level, and N represents low level.
Step S10: substituting the candidate vector obtained in the step S9 into a cost function J2In (1), calculating2Minimum switching vector, denoted as uopt(k) In that respect The cost function is as follows:
J2＝||C(Axαβ(k)+Bu(k)+Tvg(k)-xαβref(k +1)) | | formula four
A, B, C, T is a constant matrix, and is only related to the parameters of the inverter.
Step S11: will switch vector uopt(k) And converting the signal into a switching signal of a switching device of the T-type three-level converter.
Taking a T-type three-level LCL type SAPF using the control strategy of fig. 4 as an example, the validity of the proposed sequence model predictive fault-tolerant control is verified. The sequence model predictive fault-tolerant control algorithm is implemented by texas instruments 32-bit floating-point digital signal processor TMS320F 28379. The T-type three-level converter consists of six FUZI 1MBH50D-060 IGBTs and six FUZI2MBI150U2A-060 IGBTs. Six hall current sensors (HCS-LTS-06A) were used to measure the converter current and the grid current. And matching the converter voltage with the power grid voltage by adopting a fundamental frequency transformer. The non-linear load circuit is shown in fig. 5.
Table 6 shows some parameters of the T-type three-level SAPF sequence model prediction fault-tolerant control:
parameter(s) Description of the invention Value of Parameter(s) Description of the invention Value of
C1(μF) DC side capacitor 500 RC(Ω) Damping resistor 2
L1(mH) Inverter side inductor 4 Vg(V) Electric network voltage (effective value) 110
L2(mH) Network side inductor 2 I2ref(A) Amplitude of network-side reference current 10
C(μF) Filter capacitor 4 ω(rad/s) Frequency of the grid 314.16
R1(Ω) Inverter side resistor 0.1 Kp Coefficient of proportionality 0.05
R2(Ω) Network side resistor 0.1 Ki Integral coefficient 0.1
As can be seen from fig. 6, when no fault occurs, the sequence model predictive control provided by the present invention ensures excellent current compensation for SAPF, with a THD of only 2.14%; meanwhile, the voltage of the direct current bus is stabilized at 800V, and the fluctuation of the midpoint voltage is kept within 0.5V.
As can be seen from fig. 7, after the horizontal bridge arm fails, when the sequence model predictive fault-tolerant control is applied, the quality of the current waveform of the three-phase power grid is improved, and the THD is 2.68%; the voltage of the direct current bus is stabilized at 800V, and the midpoint voltage is reduced from 0.8V to 0.5V; the waveform of the output voltage of the inverter is slightly distorted in the case of a fault, a normal three-level output mode is recovered after a fault-tolerant control strategy is put into use, and the efficiency is improved.
As can be seen from fig. 8, after a vertical bridge arm has a fault, when the sequence model prediction fault-tolerant control of the present invention is applied, the three-phase power grid current waveform quality is significantly improved, and the THD is 2.98% after stabilization; the voltage of the direct current bus rises from 800V to 1200V and keeps stable, and the rising time is 50 ms; the midpoint voltage rises significantly, but the periodic fluctuations do not affect the proper operation of the dc-side capacitor. The waveform of the output voltage of the inverter is slightly distorted in the case of a fault, a normal three-level output mode is recovered after a fault-tolerant control strategy is put into use, and the efficiency is improved.
The foregoing embodiments are merely illustrative of the technical spirit and features of the present invention, and are intended to enable one skilled in the art to understand the contents of the present invention and implement the present invention without limiting the scope of the present invention, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present invention. Thus, the present invention is not intended to be limited to the embodiments shown herein but is to be accorded the widest scope consistent with the principles and novel features disclosed herein, and all equivalent changes and modifications as fall within the spirit of the invention are intended to be embraced therein.

Claims (4)

1. A T-type three-level SAPF open circuit fault sequence model prediction fault-tolerant control method is characterized by comprising the following steps: when a horizontal bridge arm or a vertical bridge arm of the T-type three-level LCL-type SAPF has a fault, the operating state after the fault is divided into a healthy state, a horizontal unhealthy state and a vertical unhealthy state by analyzing the direction of the current at the side of the inverter, and the fault-tolerant control is predicted by adopting a sequence model, so that the SAPF can normally output a compensation current, and the stability of the voltage at the direct current side and the voltage at the midpoint is ensured.
2. The method according to claim 1, characterized in that the technical idea of the sequence model predictive fault-tolerant control is as follows:
the sequence model prediction fault-tolerant control designs two cost functions of firstly controlling the midpoint voltage and then controlling the compensation current, and selects different alternative vectors and reference values of the direct current bus voltage under three operation states, so that the SAPF under the fault can obtain better current compensation effect and voltage stability under the operation of the three different states.
3. The method of claim 2, wherein the sequence model predictive fault tolerance control has the technical advantage of:
after any switching device of the T-type three-level SAPF breaks down, the sequence model prediction fault-tolerant control can continuously ensure the tracking of the compensation current, thereby preventing the harmonic pollution of a power grid and avoiding causing further loss; manpower and material resources are saved, and the reliability of the nonlinear load grid-connected system is improved; compared with the traditional model prediction fault-tolerant control, the sequence model prediction fault-tolerant control of the method saves the selection of weight factors; the method can solve the problems existing in the existing active power filter system that: the control system is complex, fault-tolerant operation is carried out, and fault-tolerant devices are redundant.
4. The method of claim 3, wherein the T-type three-level SAPF open circuit fault sequence model predictive fault-tolerant control method comprises:
distinguishing a health state, a horizontal non-health state and a vertical non-health state under the condition of the SAPF fault;
according to the difference of the three states, different reference values of the direct current bus voltage are distributed to the three states
Figure FDA0003207991630000011
Cost function J1Absolute value of the candidate vector of (a), and a cost function J1Outputting the number n of the optimal switching vectors;
through ip-iqThe method extracts reactive current and active harmonic current of a nonlinear load as reference values output by the SAPF, and simultaneously controls the voltage of a direct current side by using a PI controller;
designing a cost function J for balancing the midpoint voltage1Substituting the absolute value of the candidate vector to obtain n optimal switch vectors
Figure FDA0003207991630000012
The absolute values of the optimal switching sequences are removed to obtain a cost function J2The candidate vector of (2);
designing a cost function J for controlling the compensation current2Substituting the candidate vector into J2Finding the optimal switching vector uopt(k) And converted into input signals of the inverter switching devices.
CN202110922578.2A 2021-08-12 2021-08-12 T-type three-level SAPF open circuit fault sequence model prediction fault tolerance control method Active CN113746108B (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
CN202110922578.2A CN113746108B (en) 2021-08-12 2021-08-12 T-type three-level SAPF open circuit fault sequence model prediction fault tolerance control method

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
CN202110922578.2A CN113746108B (en) 2021-08-12 2021-08-12 T-type three-level SAPF open circuit fault sequence model prediction fault tolerance control method

Publications (2)

Publication Number Publication Date
CN113746108A true CN113746108A (en) 2021-12-03
CN113746108B CN113746108B (en) 2023-05-09

Family

ID=78730892

Family Applications (1)

Application Number Title Priority Date Filing Date
CN202110922578.2A Active CN113746108B (en) 2021-08-12 2021-08-12 T-type three-level SAPF open circuit fault sequence model prediction fault tolerance control method

Country Status (1)

Country Link
CN (1) CN113746108B (en)

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN114759817A (en) * 2022-04-07 2022-07-15 太原理工大学 Seamless open-circuit fault model prediction fault-tolerant control method suitable for cascaded full-bridge NPC inverter
CN117833248A (en) * 2024-03-06 2024-04-05 电子科技大学 Model-free predictive control method for T-shaped three-level parallel active power filter

Citations (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN107565865A (en) * 2017-09-13 2018-01-09 华中科技大学 A kind of fault-tolerant double vector prediction control method and device of six-phase permanent-magnet motor
CN107645163A (en) * 2016-07-22 2018-01-30 刘铮 A kind of new harmonic compensation method
CN107785897A (en) * 2016-08-24 2018-03-09 申茂军 A kind of New Active wave filter fault diagnosis and fault-tolerant control improvement strategy
US20180262137A1 (en) * 2017-03-08 2018-09-13 Hamilton Sundstrand Corporation Electric power generating system with a permanent magnet generator and combination of active and passive rectifiers
CN109672384A (en) * 2018-12-26 2019-04-23 天津大学 Open the design method of winding permanent magnet synchronous motor prediction fault-tolerant controller
CN109889130A (en) * 2019-03-05 2019-06-14 华中科技大学 The harmonic current control method of asymmetric six phase permanent-magnet synchronous motor
CN111162707A (en) * 2020-01-10 2020-05-15 湖南工业大学 Finite set model-free fault-tolerant predictive control method and system for permanent magnet synchronous motor

Patent Citations (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN107645163A (en) * 2016-07-22 2018-01-30 刘铮 A kind of new harmonic compensation method
CN107785897A (en) * 2016-08-24 2018-03-09 申茂军 A kind of New Active wave filter fault diagnosis and fault-tolerant control improvement strategy
US20180262137A1 (en) * 2017-03-08 2018-09-13 Hamilton Sundstrand Corporation Electric power generating system with a permanent magnet generator and combination of active and passive rectifiers
CN107565865A (en) * 2017-09-13 2018-01-09 华中科技大学 A kind of fault-tolerant double vector prediction control method and device of six-phase permanent-magnet motor
CN109672384A (en) * 2018-12-26 2019-04-23 天津大学 Open the design method of winding permanent magnet synchronous motor prediction fault-tolerant controller
CN109889130A (en) * 2019-03-05 2019-06-14 华中科技大学 The harmonic current control method of asymmetric six phase permanent-magnet synchronous motor
CN111162707A (en) * 2020-01-10 2020-05-15 湖南工业大学 Finite set model-free fault-tolerant predictive control method and system for permanent magnet synchronous motor

Non-Patent Citations (3)

* Cited by examiner, † Cited by third party
Title
MARIO SCHWEIZER 等: "Design and Implementation of a Highly Efficient Three-Level T-Type Converter for Low-Voltage Applications" *
VENKATA YARAMASU 等: "Model Predictive Current Control of Two-Level Four-Leg Inverters—Part I: Concept, Algorithm,and Simulation Analysis" *
王永辉 等: "考虑中点电压平衡的三相四开关变换器模型预测电压控制" *

Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN114759817A (en) * 2022-04-07 2022-07-15 太原理工大学 Seamless open-circuit fault model prediction fault-tolerant control method suitable for cascaded full-bridge NPC inverter
CN114759817B (en) * 2022-04-07 2024-04-12 太原理工大学 Seamless open-circuit fault model prediction fault-tolerant control method suitable for cascading full-bridge NPC inverter
CN117833248A (en) * 2024-03-06 2024-04-05 电子科技大学 Model-free predictive control method for T-shaped three-level parallel active power filter
CN117833248B (en) * 2024-03-06 2024-05-10 电子科技大学 Model-free predictive control method for T-shaped three-level parallel active power filter

Also Published As

Publication number Publication date
CN113746108B (en) 2023-05-09

Similar Documents

Publication Publication Date Title
US10439511B2 (en) Three phase inverter grid voltage feed forward method under unbalanced operating conditions
CN110867887B (en) NPC three-level inverter optimal sequence model prediction control device and method
Kouro et al. Predictive control based selective harmonic elimination with low switching frequency for multilevel converters
CN113746108A (en) T-type three-level SAPF open circuit fault sequence model prediction fault-tolerant control method
CN110460089B (en) LCL grid-connected inverter FCS-MPC control method based on multivariable prediction
de Souza et al. Grid harmonic current correction based on parallel three-phase shunt active power filter
CN111614278A (en) No-weight multivariable sequential model prediction control method and device for LCL inverter
CN110971162A (en) Improved model prediction torque control method of NPC three-level converter-PMSM system
Chenchireddy et al. A review on D-STATCOM control techniques for power quality improvement in distribution
CN104410083A (en) Capacitance midpoint potential balancing device on SVG (Static VAR Generator) direct current side and control method of capacitance midpoint potential balancing device
Marei et al. A new contribution into performance of active power filter utilizing SVM based HCC technique
US10666159B2 (en) Single-phase converter control method and apparatus
CN112532094A (en) Compound control method of T-type three-level NPC inverter
CN204290329U (en) A kind of SVG DC bus capacitor neutral-point potential balance device
CN113746107A (en) Grid-connected inverter fault-tolerant control method based on sequence model predictive control
CN113437894B (en) Common-mode voltage suppression method for three-phase eight-switch inverter
Gregor et al. Experimental Validation of the DSTATCOM Based on SiC-MOSFET Multilevel Converter for Reactive Power Compensation
CN114157171A (en) Improved model prediction current control method based on thermal management
CN114649967A (en) Pre-stage T-type three-level PFC performance optimization modulation method and system of charging system
Kkuni et al. Modelling and passivity analysis of VSC output impedance under SRF and αβ control frames
Yongchao et al. A novel SVPWM algorithm considering neutral-point potential balancing for three-level NPC inverter
CN114157170B (en) T-shaped three-level rectifier model prediction power control method based on sliding mode control
CN114256874B (en) Prediction control method for T-type inverter rapid finite set model
Limongi et al. Implementation of a digital signal processor-controlled shunt active filter
Abiri et al. A sensorless and simple controller for VSC based HVDC systems

Legal Events

Date Code Title Description
PB01 Publication
PB01 Publication
SE01 Entry into force of request for substantive examination
SE01 Entry into force of request for substantive examination
GR01 Patent grant
GR01 Patent grant