CN111669069A - Control method of AC/DC bus interface converter with midpoint potential fluctuation suppression function - Google Patents

Control method of AC/DC bus interface converter with midpoint potential fluctuation suppression function Download PDF

Info

Publication number
CN111669069A
CN111669069A CN202010488615.9A CN202010488615A CN111669069A CN 111669069 A CN111669069 A CN 111669069A CN 202010488615 A CN202010488615 A CN 202010488615A CN 111669069 A CN111669069 A CN 111669069A
Authority
CN
China
Prior art keywords
current
voltage
sub
interface converter
bus
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.)
Pending
Application number
CN202010488615.9A
Other languages
Chinese (zh)
Inventor
王金浩
任远
常潇
李胜文
王钢斌
刘翼肇
侯少健
尉镔
武志宏
李慧蓬
刘志忠
杨超颖
高乐
王锬
孟润泉
王旭
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.)
Taiyuan University of Technology
Electric Power Research Institute of State Grid Shanxi Electric Power Co Ltd
State Grid Shanxi Electric Power Co Ltd
Original Assignee
Taiyuan University of Technology
Electric Power Research Institute of State Grid Shanxi Electric Power Co Ltd
State Grid Shanxi Electric Power Co Ltd
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 Taiyuan University of Technology, Electric Power Research Institute of State Grid Shanxi Electric Power Co Ltd, State Grid Shanxi Electric Power Co Ltd filed Critical Taiyuan University of Technology
Priority to CN202010488615.9A priority Critical patent/CN111669069A/en
Publication of CN111669069A publication Critical patent/CN111669069A/en
Pending legal-status Critical Current

Links

Images

Classifications

    • 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
    • H02M7/66—Conversion of ac power input into dc power output; Conversion of dc power input into ac power output with possibility of reversal
    • H02M7/68—Conversion of ac power input into dc power output; Conversion of dc power input into ac power output with possibility of reversal by static converters
    • H02M7/72—Conversion of ac power input into dc power output; Conversion of dc power input into ac power output with possibility of reversal by static converters using discharge tubes with control electrode or semiconductor devices with control electrode
    • H02M7/79—Conversion of ac power input into dc power output; Conversion of dc power input into ac power output with possibility of reversal by static converters using discharge tubes with control electrode or semiconductor devices with control electrode using devices of a triode or transistor type requiring continuous application of a control signal
    • H02M7/797—Conversion of ac power input into dc power output; Conversion of dc power input into ac power output with possibility of reversal by static converters using discharge tubes with control electrode or semiconductor devices with control electrode using devices of a triode or transistor type requiring continuous application of a control signal using semiconductor devices only
    • 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

Landscapes

  • Engineering & Computer Science (AREA)
  • Power Engineering (AREA)
  • Supply And Distribution Of Alternating Current (AREA)

Abstract

The invention relates to the technical field of control of an AC/DC sub-network bus interface converter, in particular to a control method of an AC/DC bus interface converter with midpoint potential fluctuation suppression, which comprises the following steps of firstly, collecting AC/DC bus voltage and AC bus current and carrying out coordinate conversion; and step two, designing a droop control link, step three, designing a current closed-loop decoupling control system, and step four, wherein the design midpoint potential hysteresis control link is matched with the SVPWM modulation link. According to the invention, a three-level topology is applied to the AC/DC bus interface converter of the hybrid microgrid, so that the capacity and the voltage level of system transmission power are improved. Meanwhile, the problem that neutral point potential fluctuation influences the voltage of the direct current bus is solved while the direct current bus interface converter is proved to realize basic functions of alternating current and direct current sub-network power balance, bus voltage support, electric energy quality control and the like.

Description

Control method of AC/DC bus interface converter with midpoint potential fluctuation suppression function
Technical Field
The invention relates to the technical field of control of an AC/DC sub-network bus interface converter, in particular to a control method of a three-level AC/DC sub-network bus interface converter with midpoint potential fluctuation suppression.
Background
The interface converter of the AC/DC bus is used as a connecting pivot of the AC sub-network and the DC sub-network, not only needs to complete bidirectional power control between the AC sub-network and the DC sub-network and maintain the voltage of the sub-network bus, but also needs to realize auxiliary functions such as power quality control and the like, and is a core device of the AC/DC hybrid micro-network. At present, most of research on interface converters in an alternating current-direct current hybrid microgrid focuses on a topological structure of a three-phase two-level PWM converter, the circuit is simple, the realization is easy, and the defects of insufficient transmission capacity, small output voltage, large current harmonic wave and the like exist. Therefore, in a hybrid microgrid system with high capacity requirement and high direct-current bus voltage level requirement, the traditional three-phase two-level interface converter can be replaced by the alternating-current/direct-current sub-network bus interface converter based on the three-level topology, and the transmission capacity and the direct-current bus voltage level are improved. However, the inherent problem of midpoint potential fluctuation exists in the three-level topology, the electric energy quality of the direct-current bus voltage is seriously influenced, and the key problem that the influence of the midpoint potential fluctuation is applied to the three-level topology AC/DC sub-network bus interface converter is solved.
Disclosure of Invention
The technical problem to be solved by the invention is as follows: how to improve the capacity and the voltage grade of the transmission power of the system and how to solve the problem that the neutral point potential fluctuation influences the voltage of the direct current bus.
The technical scheme adopted by the invention is as follows: the method for controlling the AC/DC bus interface converter with the neutral point potential fluctuation suppression is carried out according to the following steps
In the AC/DC hybrid micro-grid, an AC sub-grid bus is connected with a power grid, the voltage and the current of the AC sub-grid bus are collected, the compensation current output by an AC/DC sub-grid bus interface converter is collected, and the voltage of a DC sub-grid bus is collected; with the current coordinate system as a three-phase static coordinate system abc, the magnitude (the collected voltage and current of the AC sub-network bus, the compensation current output by the interface converter and the DC sub-network bus voltage) under the three-phase static coordinate system abc is converted into the magnitude under a two-phase rotating coordinate system dq0 through equivalent transformation by using the following coordinate transformation matrix
Figure BDA0002519956700000011
Wherein, Tabc/dq0A coordinate transformation matrix representing a three-phase stationary coordinate system to a two-phase rotating coordinate system, and theta represents an included angle between an abc coordinate system and a dq0 coordinate system;
step two, controlling an interface converter of the AC/DC bus by using a droop control strategy, namely designing a droop control curve according to different characteristics of the AC/DC hybrid microgrid in a grid-connected mode and an island mode, then obtaining a corresponding relation between AC subnet bus voltage and interface converter transmission power according to the droop control curve, and controlling the interface converter; when the grid-connected mode is adopted, the support of the power grid on the alternating-current sub-network bus is considered, the amplitude and the frequency of the alternating-current sub-network bus voltage are kept consistent with the voltage information of the power grid, the maximum transmission power cannot exceed the rated transmission power of the interface converter, meanwhile, the alternating-current sub-network bus voltage is kept stable by means of the power grid, and power exchange is carried out through the interface converter; in an island mode, the loss of a power grid is considered, and a general droop control curve in the prior art is adopted to control an interface converter, so that the transmission of active power is realized;
thirdly, designing a current closed loop decoupling control system, respectively installing a voltage sensor and a current sensor at the input end and the output end of an interface converter, acquiring voltage and current information of the input end and the output end of the interface converter, dividing the transmission power of the interface converter by the bus voltage of the alternating current sub-network under a two-phase rotating coordinate system dq0 to obtain a current loop active signal instruction, enabling the bus current of the alternating current sub-network under the two-phase rotating coordinate system dq0 to pass through a harmonic detection link to extract a current loop harmonic signal instruction, adding the current loop active signal instruction and the current loop harmonic signal instruction to obtain a current loop instruction, inputting the current instruction and an actual value of the output current of the interface converter into a current regulator after a difference is made between the current instruction and the actual value of the output current of the interface converter, adding the voltage signal output by the current regulator and the alternatingAnd then decoupling is performed by subtracting the decoupling amount i from the d-axis componentfq·ωL1And adding a decoupling amount i to the q-axis componentfd·ωL1,ωL1Representing the filter reactance value, and passing (T) the voltage modulation signal under the decoupled two-phase rotating coordinate system dq0abc/dq0)-1Converting the voltage modulation signal into a voltage modulation signal under a three-phase static coordinate system abc, converting the voltage modulation signal into a voltage modulation signal under an αβ coordinate system through a coordinate transformation matrix, and inputting the voltage modulation signal and the DC sub-network bus voltage into an SVPWM (space vector pulse width modulation) link
Figure BDA0002519956700000021
Wherein, Tabc/αβRepresenting a coordinate transformation matrix;
step four, designing a neutral-point potential hysteresis control link to be matched with an SVPWM (space vector pulse width modulation) modulation link, determining neutral-point current according to the positive and negative small vectors of the modulation link and the actual value of the output current of the interface converter and according to the corresponding relation between the positive and negative small vectors and the neutral-point current, and setting a neutral-point potential hysteresis interval m-uk，uk)，ukRepresenting the limit value of the middle potential, detecting the variation delta u of the midpoint potential voltage, and comparing delta u with ukAnd when the midpoint potential exceeds the potential hysteresis interval, in the specified ratio of the positive and negative small vector action time, the positive and negative small vector action time with midpoint potential balancing capacity is gradually increased to adjust the midpoint potential and inhibit the fluctuation of the direct current bus voltage.
Positive and negative small vector and medium current corresponding meter (Table 1)
Figure BDA0002519956700000022
In table 1, which is a letter of medium positive small vector and negative small vector, referring to fig. 1, p indicates that only the upper two IGBTs of a certain phase arm are on, for example, Ta1、Ta2On, o denotes that a certain phase arm has only two diodes in the middleConducting, e.g. Da2、Da3Conducting, n indicating that only the next two IGBTs of a phase leg are conducting, e.g. Ta3、Ta4And conducting. Each phase has three switching states of p, o and n, 6 pairs of small vectors consisting of 12 small vectors generate midpoint current, each pair of small vectors corresponds to midpoint current in opposite directions, and midpoint current i is determined according to the corresponding relation shown in Table 10。
The invention has the beneficial effects that: firstly, the three-level topology is applied to an AC/DC sub-network bus interface converter of the hybrid micro-grid, so that the capacity and the voltage level of system transmission power are improved. Meanwhile, a droop control strategy with midpoint potential fluctuation suppression of the AC/DC sub-network bus interface converter in a hybrid micro-grid-connected mode and an island mode is designed, so that the AC/DC sub-network bus interface converter is ensured to realize basic functions of AC/DC sub-network power balance, bus voltage support, electric energy quality control and the like, and the problem of influence of midpoint potential fluctuation on the DC bus voltage is solved.
Drawings
Fig. 1 is a schematic diagram of a three-level ac/dc hybrid microgrid;
fig. 2 is a droop control curve of the ac/dc sub-network bus interface converter;
FIG. 3 is a droop control strategy with midpoint potential ripple hysteresis regulation;
FIG. 4 is a graph showing the effect of suppressing the midpoint potential fluctuation;
FIG. 5 is a waveform diagram of DC bus voltage when the load suddenly changes in the grid-connected mode;
fig. 6 is a simulation waveform diagram of the transmission power condition of the ac/dc sub-network and ac/dc sub-network bus interface converter when the load suddenly changes in the island mode.
Detailed Description
In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the technical solutions of the present invention will be described in detail below. It is to be understood that the described embodiments are merely exemplary of the invention, and not restrictive of the full scope of the invention. All other embodiments, which can be derived by a person skilled in the art from the examples given herein without any inventive step, are within the scope of the present invention.
Fig. 1 is a schematic diagram of a three-level ac/dc hybrid microgrid (circuit topology of three-level ac/dc sub-network bus interface converter), usaExpressed as the phase voltage of the A-phase network with respect to point n, usbExpressed as the phase voltage of the B-phase network with respect to point n, uscPhase voltage represented as C-phase grid with respect to n-point; i.e. isaRepresents the A-phase network side current, isbRepresents the B-phase network side current, iscRepresenting the C-phase network side current; u. ofacaPhase voltage u of A.C. sub-network busacbPhase voltage u of B AC sub-network busaccPhase voltage of a bus of the C alternating current sub-network; i.e. iacaFor A.C. sub-network bus current, iacbFor B AC sub-network bus current, iaccIs the bus current of the C AC sub-network; l isa、Lb、LcIs an output filter of the converter ifaFor compensating the current for phase A, ifbFor compensating the current for phase B, ifcCompensating current for phase C; t isa1、Ta2、Tb1、Tb2IGBT switching tube in bus interface converter topology of three-level AC/DC sub-network, Da1Da2Db1Db2The equal-level follow current diodes in the three-level AC/DC sub-network bus interface converter topology; i.e. i0Is the dc side midpoint current; u. ofc1、uc2The voltages of two capacitors on the direct current side are respectively; u. ofdcRepresenting the dc bus voltage.
The voltage level of the alternating-current sub-network is 380V, the voltage level of the direct-current sub-network is 750V, and the bus interface converter adopts a three-level topology. When the hybrid microgrid operates in a grid-connected mode, the switch K is closed, the power distribution network supports the bus voltage of the alternating-current sub-network, and the power balance of the hybrid microgrid is ensured; when the hybrid microgrid operates in an island mode, the switch K is switched off, and the AC/DC sub-network bus interface converter transmits power according to a preset droop curve, so that the power balance and the electric energy quality of the AC/DC sub-network are ensured.
The droop control strategy with midpoint potential fluctuation suppression is realized by the three-level topological AC/DC sub-network bus interface converter, a preset droop curve is shown in fig. 2, and a specific control strategy block diagram is shown in fig. 3, and the method specifically comprises the following steps:
step one, collecting A, B, C AC sub-network bus voltage uaca，uacb,uacc(ii) a Collecting A, B, C AC sub-network bus current iaca,iacb,iacc(ii) a Collecting A, B, C-phase compensation current i output by AC/DC sub-network bus interface converterfa,ifb，ifc(ii) a Collecting bus voltage u of DC sub-networkdc；
Converting the amount in the three-phase stationary coordinate system into the amount in the two-phase rotating coordinate system by equivalent transformation by using the following coordinate transformation formula;
Figure BDA0002519956700000041
obtain the bus voltage u of the AC sub-networkacd，uacq(ii) a Ac sub-network bus current iacd,iacq；
Wherein, Tabc/dq0The field of power electronics control generally converts the abc coordinate system, in which variable signals need to be controlled, into a rotating dq0 coordinate system, converting three-phase alternating current signals into direct current signals, which makes it possible to more effectively control an electrical system. θ represents the angle between the abc coordinate system and the dq0 coordinate system; a, B, C AC sub-network bus voltage uaca,uacb, uaccConversion to u in dq0 coordinate systemacd,uacqAnd the alternating current sub-network bus voltage of the abc coordinate system is converted into a variable under the dq0 coordinate system, so that the variable can be more effectively controlled. E.g. uacaRepresenting the value of the AC sub-network bus voltage in phase A, uacbRepresenting the value of the AC sub-network bus voltage in phase B, uaccIndicating that the AC sub-network bus voltage is atThe value of C phase, transformed by coordinate axes, uacdRepresenting the value of the AC sub-network bus voltage on the d axis, uacdAnd the value of the alternating current sub-network bus voltage on a q coordinate axis is shown.
Step two, controlling the interface converter of the AC/DC bus by using a droop control strategy:
fig. 2 is a droop control curve of the ac/dc sub-network bus interface converter, (a) and (b) indicate that the system is in a grid-connected mode, (a) in the graph, the abscissa indicates the ac sub-network bus voltage, and the ordinate indicates the transmission power P of the ac/dc sub-network bus interface converterac，UacNThe voltage value is the constant voltage value of the AC sub-network bus, the AC/DC sub-network bus interface converter is in a shutdown mode at the moment, and the transmission power is zero; u shapeacL1、UacH1The lower limit value and the upper limit value of the normal fluctuation of the bus voltage of the alternating-current sub-network are set; u shapeacL2、UacH2The method comprises the following steps of (1) setting a lower limit value and an upper limit value of a bus droop mode of an alternating-current sub-network; u shapeacL2-UacL1Section, AC/DC sub-network bus interface converter in rectification state, UacH1-UacH2In a section, the AC/DC sub-network bus interface converter is in an inversion state; (b) in the figure, the abscissa represents the direct-current bus voltage, and the ordinate represents the transmission power P of the AC-DC sub-network bus interface converterdc，UdcNThe voltage value of the direct current bus is a constant voltage value, at the moment, the alternating current/direct current sub-network bus interface converter is in a shutdown mode, and the transmission power is zero; u shapedcL1、UdcH1The lower limit value and the upper limit value of the normal fluctuation of the direct current bus voltage; u shapedcL2、UdcH2The lower limit value and the upper limit value of the direct current bus droop mode are obtained; u shapedcL2-UdcL1Section, AC/DC sub-network bus interface converter in rectification state, UdcH1-UdcH2In a section, the AC/DC sub-network bus interface converter is in an inversion state; (c) in the graph, the abscissa represents the voltage of the alternating-current sub-network bus, and the ordinate represents the transmission power P of the alternating-current and direct-current sub-network bus interface converterac，UacNThe voltage value of the AC sub-network bus is constant, the AC/DC sub-network bus interface converter is in a shutdown mode at the moment, and the transmission power is zero；UacL1、UacH1The lower limit value and the upper limit value of the normal fluctuation of the bus voltage of the alternating-current sub-network are set; u shapeacL2、UacH2The method comprises the following steps of (1) setting a lower limit value and an upper limit value of a bus droop mode of an alternating-current sub-network; u shapeacL2-UacL1Section, AC/DC sub-network bus interface converter in rectification state, UacH1-UacH2In a section, the AC/DC sub-network bus interface converter is in an inversion state; (d) in the figure, the abscissa represents the direct-current bus voltage, and the ordinate represents the transmission power P of the AC-DC sub-network bus interface converterdc，UdcNThe voltage value of the direct current bus is a constant voltage value, at the moment, the alternating current/direct current sub-network bus interface converter is in a shutdown mode, and the transmission power is zero; u shapedcL1、UdcH1The lower limit value and the upper limit value of the normal fluctuation of the direct current bus voltage; u shapedcL2、UdcH2The lower limit value and the upper limit value of the direct current bus droop mode are obtained; u shapedcL2-UdcL1Section, AC/DC sub-network bus interface converter in rectification state, UdcH1-UdcH2And in the section, the AC/DC sub-network bus interface converter is in an inversion state. According to different characteristics of the AC/DC hybrid microgrid under a grid-connected mode and an island mode, droop control curves are respectively designed for different modes:
when the system operates in a grid-connected mode, the support of a national power grid on an alternating-current sub-network bus is considered, the amplitude and the frequency of the alternating-current sub-network bus voltage are consistent with the voltage information of the power grid, and the maximum alternating-current transmission power cannot exceed the rated transmission power of an interface converter (namely, a device for realizing alternating-current and direct-current conversion at the interface of an alternating-current distribution network and a direct-current distribution network); meanwhile, the voltage of the direct current bus is maintained to be stable by means of the national power grid, and power exchange is carried out through the interface converter;
when the system operates in an island mode, the loss of the power grid is considered, and the U of the alternating current sub-network and the direct current sub-network which are established according to the droop rule of the prior art is taken into considerationac-PacAnd Udc-PdcThe curve is shown in fig. 2, and the transmission of active power is carried out.
Designing a current closed-loop decoupling control system:
will generate electricityThe voltage and current sensors are arranged at the two ends of the input and the output of the AC-DC sub-network bus interface converter, collect voltage, current and power information, and divide the obtained transmission power and the AC sub-network bus voltage under the dq0 coordinate system to obtain a d-axis component i of the current loop active signal instructionfdref1And q-axis component ifqref1(ii) a Extracting a d-axis component i of a current loop harmonic signal instruction from the collected alternating current sub-network bus current under the dq0 coordinate system through a harmonic detection link in the prior artdref2And q-axis component iqref2(ii) a Adding the current loop active signal instruction and the harmonic signal instruction to obtain a current loop instruction current d-axis component idrefAnd q-axis component iqref(ii) a Will current command idrefAnd iqrefActual value i of output current of signal and interface converterfd，ifqRespectively making difference and inputting the difference into a current regulator; the voltage signal output by the current regulator is subjected to a link with a gain of-1 and then is summed with uacd，uacqAdding and subtracting the decoupling amount i in d-axis controlfq·ωL1And adding a decoupling amount i to the q-axis controlfd·ωL1Wherein, ω L1Representing a filter reactance value; the obtained modulation signal under dq0 coordinate system is subjected to (T)abc/dq0)-1Converting to abc coordinate system, converting to αβ coordinate system by known coordinate formula, and converting to u coordinate systemdcInputting the signals into an SVPWM (space vector pulse width modulation) link together;
Figure BDA0002519956700000051
wherein, Tabc/αβThe general transformation matrix formula which represents the coordinate transformation matrix, namely converting the abc coordinate system into the αβ coordinate system converts the obtained variables into the variables under the αβ coordinate system, and the variables can be more effectively controlled.
Step four, designing a neutral potential hysteresis control link to be matched with an SVPWM (space vector pulse width modulation) link;
according to the small vector of the modulation link and the actual output current i of the interface converterfDetermining the midpoint current i according to the corresponding relationship shown in Table 10(ii) a Set midpoint voltagePosition hysteresis loop interval m ═ uk，uk)，ukRepresenting the limit value of the middle potential, detecting the variation delta u of the midpoint potential voltage, and comparing delta u with ukMaking difference value, namely deviation degree, and keeping original small vector action time unchanged when the midpoint potential is within m; when the midpoint potential exceeds the interval m, the small vector action time with midpoint potential balancing capacity is gradually increased in the specified ratio of the small vector action time to adjust the midpoint potential and inhibit the fluctuation of the direct-current bus voltage.
The figure 4 is a simulation waveform of the midpoint potential adjustment. Before t is 1.0s, a fully symmetrical seven-segment SVPWM modulation method is adopted for modulation, namely the action time of a positive small vector and the action time of a negative small vector are completely equal, the midpoint potential is not controlled, and the midpoint potential deviation is gradually enlarged; when t is 1.0s, the hysteresis loop of the midpoint potential is adjusted by using the midpoint current, ik＝0.5A，ukThe shift of the midpoint potential is gradually reduced at 1V, and is limited to the hysteresis band m.
Fig. 5 is a simulation waveform of the dc bus voltage of the hybrid microgrid in the grid-connected mode. At 0.2s and 0.4s, load sudden increase and load sudden decrease are respectively simulated, and it can be seen that under the designed improved control strategy, the alternating current-direct current sub-network bus interface converter can ensure that the direct current voltage is recovered to the initial state within 0.2 s.
Fig. 6 is a simulation waveform of power transmission of the hybrid microgrid in an island mode. Fig. 6(a) shows output voltage and current of the ac/dc sub-network bus interface converter; fig. 6(b) shows transmission power of the ac/dc sub-network bus interface converter; fig. 6(c) shows the output situation of the ac subnetwork and the dc subnetwork. As can be seen from fig. 6, the ac/dc sub-network bus interface converter operates in a shutdown mode in 0-0.2 s, the transmission power is 0, and the ac/dc sub-networks output power according to their respective rated capacities; when load fluctuation occurs in 0.2s and 0.4s, the AC/DC sub-network bus interface converter respectively enters an inversion mode and a rectification mode to transmit power, and the AC/DC sub-network is ensured to output power in equal proportion according to respective capacity.
The above description is only for the purpose of illustrating the preferred embodiments of the present invention and is not to be construed as limiting the invention, and any modifications, equivalents and improvements made within the spirit and principle of the present invention are intended to be included within the scope of the present invention.

Claims (1)

1. The control method of the AC/DC bus interface converter with the neutral point potential fluctuation suppression is characterized by comprising the following steps: the method comprises the following steps
In the AC/DC hybrid micro-grid, an AC sub-grid bus is connected with a power grid, the voltage and the current of the AC sub-grid bus are collected, the compensation current output by an AC/DC sub-grid bus interface converter is collected, and the voltage of a DC sub-grid bus is collected; using the current coordinate system as the three-phase stationary coordinate system abc, and using the following coordinate transformation matrix, the magnitude in the three-phase stationary coordinate system abc is converted into the magnitude in the two-phase rotating coordinate system dq0 through equivalent transformation
Figure FDA0002519956690000011
Wherein, Tabc/dq0A coordinate transformation matrix representing a three-phase stationary coordinate system to a two-phase rotating coordinate system, and theta represents an included angle between an abc coordinate system and a dq0 coordinate system;
step two, controlling an interface converter of the AC/DC bus by using a droop control strategy, namely designing a droop control curve according to different characteristics of the AC/DC hybrid microgrid in a grid-connected mode and an island mode, then obtaining a corresponding relation between AC subnet bus voltage and interface converter transmission power according to the droop control curve, and controlling the interface converter; when the grid-connected mode is adopted, the support of the power grid on the alternating-current sub-network bus is considered, the amplitude and the frequency of the alternating-current sub-network bus voltage are kept consistent with the voltage information of the power grid, the maximum transmission power cannot exceed the rated transmission power of the interface converter, meanwhile, the alternating-current sub-network bus voltage is kept stable by means of the power grid, and power exchange is carried out through the interface converter; in an island mode, the loss of a power grid is considered, and a general droop control curve in the prior art is adopted to control an interface converter, so that the transmission of active power is realized;
thirdly, designing a current closed loop decoupling control system, respectively installing voltage and current sensors at the input and output ends of an interface converter, acquiring voltage and current information of the input and output ends of the interface converter, dividing the transmission power of the interface converter by the bus voltage of the alternating current sub-network under a two-phase rotating coordinate system dq0 to obtain a current loop active signal instruction, enabling the bus current of the alternating current sub-network under the two-phase rotating coordinate system dq0 to pass through a harmonic detection link to extract a current loop harmonic signal instruction, adding the current loop active signal instruction and the current loop harmonic signal instruction to obtain a current loop instruction, inputting the current instruction and the actual value of the output current of the interface converter into a current regulator after making a difference, adding a voltage signal output by the current regulator with the bus voltage of the alternating current sub-network under the two-phase rotating coordinate system dq0 after passing through a gain-1 link, and, i.e. subtracting the decoupling amount i from the d-axis componentfq·ωL1And adding a decoupling amount i to the q-axis componentfd·ωL1,ωL1Representing the filter reactance value, and passing (T) the voltage modulation signal under the decoupled two-phase rotating coordinate system dq0abc/dq0)-1Converting the voltage modulation signal into a voltage modulation signal under a three-phase static coordinate system abc, converting the voltage modulation signal into a voltage modulation signal under an αβ coordinate system through a coordinate transformation matrix, and inputting the voltage modulation signal and the DC sub-network bus voltage into an SVPWM (space vector pulse width modulation) link
Figure FDA0002519956690000012
Wherein, Tabc/αβRepresenting a coordinate transformation matrix;
step four, designing a neutral-point potential hysteresis control link to be matched with an SVPWM (space vector pulse width modulation) modulation link, determining neutral-point current according to the positive and negative small vectors of the modulation link and the actual value of the output current of the interface converter and according to the corresponding relation between the positive and negative small vectors and the neutral-point current, and setting a neutral-point potential hysteresis interval m-uk，uk)，ukRepresenting the limit value of the middle potential, detecting the variation delta u of the midpoint potential voltage, and comparing delta u with ukTaking a difference value, namely the deviation degree and the midpoint potentialWhen the neutral potential exceeds the potential hysteresis interval, the action time of the positive and negative small vectors with neutral potential balancing capability is gradually increased in the specified ratio of the action time of the positive and negative small vectors to adjust the neutral potential and inhibit the fluctuation of the DC bus voltage.
CN202010488615.9A 2020-06-02 2020-06-02 Control method of AC/DC bus interface converter with midpoint potential fluctuation suppression function Pending CN111669069A (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
CN202010488615.9A CN111669069A (en) 2020-06-02 2020-06-02 Control method of AC/DC bus interface converter with midpoint potential fluctuation suppression function

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
CN202010488615.9A CN111669069A (en) 2020-06-02 2020-06-02 Control method of AC/DC bus interface converter with midpoint potential fluctuation suppression function

Publications (1)

Publication Number Publication Date
CN111669069A true CN111669069A (en) 2020-09-15

Family

ID=72385617

Family Applications (1)

Application Number Title Priority Date Filing Date
CN202010488615.9A Pending CN111669069A (en) 2020-06-02 2020-06-02 Control method of AC/DC bus interface converter with midpoint potential fluctuation suppression function

Country Status (1)

Country Link
CN (1) CN111669069A (en)

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN113013931A (en) * 2021-03-11 2021-06-22 国网山西省电力公司经济技术研究院 Power self-adaptive balance control method and system for alternating current-direct current power distribution system
CN116683778A (en) * 2023-06-15 2023-09-01 西南交通大学 Single-phase AC-DC-AC converter and comprehensive coordination control method thereof

Citations (10)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN102738826A (en) * 2012-06-11 2012-10-17 合肥工业大学 Leakage current restraining method for improved LCL (Lower Control Limit) filter and even balance control method
CN103151917A (en) * 2013-03-22 2013-06-12 天津大学 Duty cycle disturbance control method of composite two-way three-level direct-current converter for micro-grid energy storage
CN103825291A (en) * 2014-02-24 2014-05-28 国家电网公司 Method for controlling modularized three-level energy storage in grid-connected state and grid-disconnected state
CN203747688U (en) * 2014-02-20 2014-07-30 南京冠亚电源设备有限公司 Three-level grid-connected inverter
CN107222121A (en) * 2017-05-25 2017-09-29 太原理工大学 A kind of autonomous progress control method of bidirectional power converter
CN108462199A (en) * 2018-01-26 2018-08-28 许继集团有限公司 A kind of isolated island current conversion station and its AC fault traversing method
CN108565885A (en) * 2018-01-16 2018-09-21 浙江大学 A kind of mesohigh large capacity cascade type energy storage system control method based on VSG
CN109347347A (en) * 2018-10-11 2019-02-15 南京航空航天大学 The universal 3D-SVPWM control method of three-phase four-wire three-level inverter and control system under unbalanced load
CN110460056A (en) * 2019-08-01 2019-11-15 太原理工大学 The control method for coordinating of series compensation link and alternating current-direct current bus interface converter
CN111211697A (en) * 2020-01-15 2020-05-29 西安交通大学 Modular multi-level high-power AC-AC converter based on high-frequency transformer

Patent Citations (10)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN102738826A (en) * 2012-06-11 2012-10-17 合肥工业大学 Leakage current restraining method for improved LCL (Lower Control Limit) filter and even balance control method
CN103151917A (en) * 2013-03-22 2013-06-12 天津大学 Duty cycle disturbance control method of composite two-way three-level direct-current converter for micro-grid energy storage
CN203747688U (en) * 2014-02-20 2014-07-30 南京冠亚电源设备有限公司 Three-level grid-connected inverter
CN103825291A (en) * 2014-02-24 2014-05-28 国家电网公司 Method for controlling modularized three-level energy storage in grid-connected state and grid-disconnected state
CN107222121A (en) * 2017-05-25 2017-09-29 太原理工大学 A kind of autonomous progress control method of bidirectional power converter
CN108565885A (en) * 2018-01-16 2018-09-21 浙江大学 A kind of mesohigh large capacity cascade type energy storage system control method based on VSG
CN108462199A (en) * 2018-01-26 2018-08-28 许继集团有限公司 A kind of isolated island current conversion station and its AC fault traversing method
CN109347347A (en) * 2018-10-11 2019-02-15 南京航空航天大学 The universal 3D-SVPWM control method of three-phase four-wire three-level inverter and control system under unbalanced load
CN110460056A (en) * 2019-08-01 2019-11-15 太原理工大学 The control method for coordinating of series compensation link and alternating current-direct current bus interface converter
CN111211697A (en) * 2020-01-15 2020-05-29 西安交通大学 Modular multi-level high-power AC-AC converter based on high-frequency transformer

Non-Patent Citations (2)

* Cited by examiner, † Cited by third party
Title
SHENGWEN LI等: ""The Bidirectional AC/DC Power Converter with Capability of Suppressing the Harmonic Current in Hybrid Micro Grid"" *
何晶: "基于三电平变流器SVPWM简化算法的中点电压控制及并网策略研究" *

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN113013931A (en) * 2021-03-11 2021-06-22 国网山西省电力公司经济技术研究院 Power self-adaptive balance control method and system for alternating current-direct current power distribution system
CN116683778A (en) * 2023-06-15 2023-09-01 西南交通大学 Single-phase AC-DC-AC converter and comprehensive coordination control method thereof
CN116683778B (en) * 2023-06-15 2024-02-27 西南交通大学 Single-phase AC-DC-AC converter and comprehensive coordination control method thereof

Similar Documents

Publication Publication Date Title
CN101534065B (en) Asymmetric direct power control method of grid-connected three-phase voltage source converter
WO2021233190A1 (en) Dual-mode combined control method for multi-inverter system based on double split transformer
US8907509B2 (en) Current controller device and vector control method for controlling power conversion
CN110829466B (en) NPC three-level model prediction unbalance treatment method for combined switch state
CN104167941B (en) Three-phase PWM rectifier control method
CN109830966B (en) Three-phase four-wire system electric energy quality comprehensive treatment device and control method and system thereof
CN107611991B (en) Parameter design method of LC coupling type SVG under unbalanced power grid and control method and system thereof
CN108418226B (en) Reactive compensation control method of open-winding double-inverter photovoltaic power generation system
CN108879775B (en) Power grid unbalanced photovoltaic inverter coordination control method considering current limit value
CN112653342B (en) Complex vector current loop decoupling control device and method under static coordinate system
CN111669069A (en) Control method of AC/DC bus interface converter with midpoint potential fluctuation suppression function
Challa et al. Modeling, Controlling Approaches, Modulation Schemes, and Applications of Modular Multilevel Converter
CN105071390B (en) Control method of H-bridge three-level active power filter and system
Jabbarnejad et al. Virtual-flux-based DPC of grid connected converters with fast dynamic and high power quality
CN112564167B (en) Improved droop control method based on consistency algorithm
CN113489397A (en) Adaptive control and correction method for electronic transformer in digital substation
CN112510749A (en) Droop control method with network self-adaption capability in micro-grid island mode
Das et al. State of art control techniques for DSTATCOM
CN218041204U (en) Three-phase active control circuit and topological structure
CN113437855B (en) Generalized Clarke coordinate transformation and three-phase control circuit
CN113346765A (en) In-phase power supply device topological structure based on balance transformer and control method
CN112583289B (en) Upper and lower bus current cooperative control method for parallel operation of current source type rectifiers
CN111800028A (en) Novel method for restraining power fluctuation and circulation of railway traction power supply system
CN114400719A (en) New energy grid-connected control circuit and SST control method based on virtual synchronous machine
CN113765428A (en) Active neutral point clamped three-level converter and regulation and control method thereof

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
RJ01 Rejection of invention patent application after publication

Application publication date: 20200915

RJ01 Rejection of invention patent application after publication