WO2023131300A1 - 模块化多电平换流器桥臂电流方向的判断方法及控制系统 - Google Patents

模块化多电平换流器桥臂电流方向的判断方法及控制系统 Download PDF

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WO2023131300A1
WO2023131300A1 PCT/CN2023/071017 CN2023071017W WO2023131300A1 WO 2023131300 A1 WO2023131300 A1 WO 2023131300A1 CN 2023071017 W CN2023071017 W CN 2023071017W WO 2023131300 A1 WO2023131300 A1 WO 2023131300A1
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Prior art keywords
current
bridge arm
voltage
value
judging
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PCT/CN2023/071017
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English (en)
French (fr)
Inventor
卢宇
董云龙
张君君
邵震霞
周谷庆
胡兆庆
任铁强
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南京南瑞继保电气有限公司
南京南瑞继保工程技术有限公司
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Priority to DE112023000326.2T priority Critical patent/DE112023000326T5/de
Publication of WO2023131300A1 publication Critical patent/WO2023131300A1/zh

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    • 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
    • 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
    • H02M7/4835—Converters with outputs that each can have more than two voltages levels comprising two or more cells, each including a switchable capacitor, the capacitors having a nominal charge voltage which corresponds to a given fraction of the input voltage, and the capacitors being selectively connected in series to determine the instantaneous output voltage
    • 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
    • H02M7/53—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 using devices of a triode or transistor type requiring continuous application of a control signal
    • H02M7/537—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 using devices of a triode or transistor type requiring continuous application of a control signal using semiconductor devices only, e.g. single switched pulse inverters
    • H02M7/5387—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 using devices of a triode or transistor type requiring continuous application of a control signal using semiconductor devices only, e.g. single switched pulse inverters in a bridge configuration
    • 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
    • Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
    • Y02E60/60—Arrangements for transfer of electric power between AC networks or generators via a high voltage DC link [HVCD]

Definitions

  • the present application relates to the technical field of power electronics, in particular to a method for judging the current direction of a bridge arm of a modular multilevel converter, a control system, electronic equipment, and a computer-readable medium.
  • Modular multilevel converters are widely used in power electronic systems such as flexible direct current transmission projects, static synchronous compensators, and low-frequency power transmission.
  • Each bridge arm of the modular multilevel converter is composed of N sub-modules connected in series.
  • the input quantity of converter sub-modules is generally controlled by the valve control system.
  • the valve control system is an intermediate bridge between the converter control protection system and the converter sub-module.
  • the valve control system receives the control command of the converter control and protection system and modulates it to obtain the number of sub-modules that need to be invested in each converter bridge arm, and finally selects the appropriate sub-module for input.
  • the general principle is to select a sub-module with a lower voltage to input when the bridge arm is charging (that is, the direction of the bridge arm current is positive), and to discharge the bridge arm (that is, the direction of the bridge arm current is negative)
  • the sub-module with higher voltage is selected to be input, so as to realize the balance of the voltage of the sub-modules inside the whole bridge arm. Therefore, the judgment of the bridge arm current direction is one of the key functions of the valve control system. Accurate and effective bridge arm current direction judgment strategy plays an important role in both the voltage control of the converter sub-module and the suppression of the switching frequency of the sub-module.
  • the direction of the bridge arm current is usually judged by the positive or negative of the bridge arm current sampling value.
  • this judgment method has errors in the direction judgment when the bridge arm current is small, causing disorder in the input of the sub-module, resulting in overvoltage of the sub-module, high-frequency input, etc. problems that endanger system operation security.
  • the method of judging the direction of the bridge arm current by setting the anti-shake time under the condition of small current due to sampling error and other factors, the bridge arm current is distorted near zero. Therefore, the real current direction cannot be accurately judged only by the anti-shake time.
  • this application provides a method for judging the current direction of the bridge arm of a modular multilevel converter, including:
  • the direction of the current is reversed according to a fixed period, and the result of the reversal is used as the direction of the current.
  • the judging method before using the first judgment mode to determine the direction of the current, further includes: comparing the collected current value of the bridge arm with the set first positive threshold and second negative threshold comparison; where, when the current value is less than the first positive threshold and greater than the second negative threshold, the first judgment mode is used to determine the direction of the current.
  • the duration of the period variation of the voltage of the capacitor in the bridge arm is a positive value is not less than the first anti-shake time or the duration of the period variation is a negative value is not less than the second
  • anti-shake time is used, the positive or negative of the period variation is taken as the direction of the current.
  • the period variation includes:
  • the voltage of the capacitor includes:
  • the reversing the current according to a fixed period includes:
  • the current direction of the bridge arm is changed every first period.
  • the first period includes: N times or one-Nth of the current period of the bridge arm, where N is a natural number greater than or equal to 1.
  • the first judgment mode is used to determine the direction of the current.
  • the judging method further includes:
  • the direction of the current is determined by using the first judgment mode or the second judgment mode; wherein, the second judgment Patterns include,
  • the positive and negative values of the current are taken as the direction of the current.
  • the first judgment mode or The second judgment mode determines the direction of the current flow.
  • a control system for a modular multilevel converter comprising:
  • a measuring unit configured to measure the current value of each bridge arm in the converter or the voltage value of the capacitance of each sub-module
  • valve control system configured to receive the current value of the bridge arm or the voltage value of the capacitor measured by the measuring unit
  • a converter control and protection system configured to send a voltage reference wave of the bridge arm of the converter to the valve control system
  • the valve control system is also used to control the input quantity of the bridge arm of the inverter according to the voltage reference wave, and judge the bridge arm of the inverter according to the current value or voltage value using the above judgment method The direction of the current, and then send a trigger command to the converter according to the direction of the current.
  • processors one or more processors
  • the one or more processors are made to implement the above judging method.
  • a computer-readable medium on which a computer program is stored, and when the program is executed by a processor, the above judging method is realized.
  • the method for judging the bridge arm current direction of the modular multilevel converter judges the bridge arm current direction according to the relationship between the bridge arm current sampling value and the threshold value when the bridge arm current is relatively large;
  • the current direction of the bridge arm is judged by using a fixed period of flipping or the change of the capacitor voltage of the internal sub-module of the bridge arm, which can avoid the problem of distortion of the bridge arm current sampling caused by factors such as current sampling zero drift under low current conditions.
  • This judgment method can accurately judge the direction of the bridge arm current under any working condition, especially under the low-load operation condition with small bridge arm current, and provide accurate instructions for the sub-module input control strategy of the valve control system. To ensure the safe and reliable operation of the system to the maximum extent.
  • Fig. 1 shows a schematic diagram of a bridge arm of a modular multilevel converter according to an exemplary embodiment of the present application
  • FIG. 2 shows a flowchart of a method for judging the direction of a bridge arm current according to a first exemplary embodiment of the present application
  • FIG. 3 shows a flowchart of a method for judging the direction of a bridge arm current according to a second exemplary embodiment of the present application
  • Fig. 4 shows a schematic diagram of the judgment logic of the bridge arm current direction according to the second exemplary embodiment of the present application
  • Fig. 5 shows a schematic diagram of a bridge arm current direction according to a second exemplary embodiment of the present application
  • FIG. 6 shows a flowchart of a method for judging the direction of a bridge arm current according to a third exemplary embodiment of the present application
  • Fig. 7 shows the logical diagram according to the first judgment mode of the third exemplary embodiment of the present application.
  • Fig. 8 shows a schematic diagram of the direction of the bridge arm current in the first judgment mode according to the third exemplary embodiment of the present application
  • FIG. 9 shows a flowchart of a method for judging the direction of a bridge arm current according to a fourth exemplary embodiment of the present application.
  • Fig. 10 shows a schematic diagram of the judgment logic of the bridge arm current direction according to the fourth exemplary embodiment of the present application.
  • Fig. 11 shows a schematic diagram of a bridge arm current direction according to a fourth exemplary embodiment of the present application.
  • FIG. 12 shows a schematic diagram of a modular multilevel converter control system according to an exemplary embodiment of the present application
  • Fig. 13 shows a block diagram of electronic equipment used for judging the current direction of a bridge arm of a modular multilevel converter according to an exemplary embodiment of the present application.
  • Example embodiments will be described more fully hereinafter with reference to the accompanying drawings. Example embodiments may, however, be embodied in many forms and should not be construed as limited to the embodiments set forth herein. These embodiments are provided so that this application will be thorough and complete, and will fully convey the concept of example embodiments to those skilled in the art. The same reference numerals denote the same or similar parts in the drawings, and thus their repeated descriptions will be omitted.
  • Fig. 1 shows a schematic diagram of a bridge arm of a modular multilevel converter according to an example embodiment of the present application.
  • a bridge arm 100 of a modular multilevel converter 1000 is composed of N submodules 110 connected in series, for example, No. 1 submodule, No. 2 submodule, No. 3 submodule
  • the submodules, ..., N submodules are connected in series with each other.
  • the topology of each sub-module 110 may be in various forms such as half-bridge, full-bridge, and quasi-full-bridge.
  • the half-bridge sub-module 110 includes a DC capacitor 111 and a circuit composed of IGBT1 and IGBT2 in series connected in parallel therewith. Each IGBT is connected in parallel with a reverse diode 112 .
  • this application provides a current direction judgment method, according to the bridge arm current
  • the sampling value is used to determine the working condition of the bridge arm, and then different judgment methods are selected for judgment, so as to avoid the problem of wrong judgment of the current direction when the current sampling value is small, that is, when the current value of the bridge arm is large (the absolute value of the current is greater than the current 0.00001 to 1 times the peak value, such as 5/1000, which can be adjusted according to the actual situation), it is judged to be in a normal working condition, and the current direction of the bridge arm current is obtained according to the comparison between the bridge arm current sampling value and the threshold value; when the bridge arm current When the value is small (the absolute value of the current is less than 0.00001 to 1 times the peak value of the current, for example, 5/1000, which can be adjusted according to the actual situation), after judging that it has entered the low-load working condition
  • the working condition of the bridge arm current is not judged, and the method for determining the bridge arm current in the first judgment mode can be used at any current value.
  • the first judgment mode includes taking the positive or negative of the periodic variation of the voltage of the capacitor in the bridge arm as the direction of the current. That is, when the period variation is greater than zero, the bridge arm current is in a positive direction and is in a charging state; when the period variation is less than zero, the bridge arm current is in a negative direction and is in a discharging state. When the period variation is zero, keep the last judgment result.
  • the voltage Uc(n) of the capacitor may be the sum of the voltages of the capacitors of all sub-modules in the bridge arm, or the average voltage of the capacitors of all the sub-modules in the bridge arm.
  • the anti-shake time may also be set for the periodic variation of the voltage of the capacitor in the bridge arm. For example, when the duration of the period variation of the voltage of the capacitor in the bridge arm is a positive value is not less than the first anti-shake time or the duration of the period variation is negative is not less than the second anti-shake time, the period variation Positive and negative as the direction of the current.
  • the first anti-shake time and the second anti-shake time may be equal or unequal, and specific settings may be made according to actual needs.
  • the first judgment mode includes taking the positive or negative of the periodic variation of the voltage of the capacitor in the bridge arm as the direction of the current.
  • the current direction of the bridge arm is changed every first period. After period reversal, the generated bridge arm current direction is taken as the judgment result.
  • the first period may be N times or one-Nth of the current period of the bridge arm, where N is a natural number greater than or equal to 1.
  • the first period may be 0.5Ts, where Ts is the theoretical period of the bridge arm current.
  • the period of the bridge arm current is 20ms, and the direction of the bridge arm current can be changed every 10ms.
  • Fig. 2 shows a flowchart of a method for judging the direction of a bridge arm current according to the first exemplary embodiment of the present application.
  • the method for judging the current direction of the bridge arm of the modular multilevel converter provided by the present application includes the following steps.
  • step S210 the collected current value of the bridge arm is compared with a set first positive threshold and a second negative threshold. Normally, when the bridge arm current value Ib of the converter is greater than or equal to the set first positive threshold Is1 or less than or equal to the set second negative threshold Is2, the converter is in a normal working condition (that is, Ib ⁇ Is1 or Ib ⁇ Is2); when the bridge arm current value Ib of the inverter is less than the set first threshold Is1 and greater than the set second negative threshold Is2 (that is, Is2 ⁇ Ib ⁇ Is1), the inverter is at low load condition.
  • the first positive threshold for judging the working condition of the converter can be set to 0.00001 to 1 times (for example, five thousandths) of the positive peak value of the bridge arm current
  • the second negative threshold can also be set to It is set as 0.00001-1 times (for example, 5/1000) of the negative peak value of the bridge arm current, which is not limited in the present application.
  • step S220 when the current value is less than the first positive threshold and greater than the second negative threshold, a first judgment mode is used to determine the direction of the current; wherein the first judgment mode includes controlling the The direction of the current is reversed according to a fixed period, and the result of the reversal is used as the direction of the current.
  • the current of the bridge arm can be controlled to be reversed according to a fixed cycle, for example, the current direction of the bridge arm is changed once every first cycle. After period reversal, the generated bridge arm current direction is taken as the judgment result.
  • the first period may be N times or one-Nth of the current period of the bridge arm, where N is a natural number greater than or equal to 1.
  • the first period may be 0.5Ts, where Ts is the theoretical period of the bridge arm current.
  • the period of the bridge arm current is 20ms, and the direction of the bridge arm current can be changed every 10ms.
  • the anti-shake time may also be set for the determination of the low-load condition. For example, when the current value of the bridge arm is less than the first positive threshold and greater than the second negative threshold for a duration not less than the set third anti-shake time, the first judgment mode is used to determine the direction of the current. By setting the anti-shake time, frequent switching of working condition judgment results can be avoided.
  • the third anti-shake time may be set as a plurality of task cycle times.
  • Fig. 3 shows a flowchart of a method for judging the direction of a bridge arm current according to a second exemplary embodiment of the present application.
  • the judging method shown in FIG. 2 may further include the following steps.
  • step S230 when the current value is greater than or equal to the first positive threshold or less than or equal to the second negative threshold, the direction of the current is determined by using the first judgment mode or the second judgment mode; wherein, the first The second judgment mode includes taking the positive or negative of the current value as the direction of the current.
  • the bridge arm When the current value of the bridge arm is greater than or equal to the set first positive threshold or less than or equal to the set second negative threshold, the bridge arm is in a normal working condition.
  • the direction of the current can be determined according to the positive or negative of the collected current value.
  • the direction of the current may also be reversed according to a fixed period by controlling the direction of the current, and the result of the reversal may be used as the direction of the current.
  • the current direction of the bridge arm is changed every second period. After period reversal, the generated bridge arm current direction is taken as the judgment result.
  • the second period and the first period may be the same or different.
  • an anti-shake time may also be set for determining normal working conditions. For example, when the current value of the bridge arm is greater than or equal to the first positive threshold or less than or equal to the second negative threshold for a duration not less than the fourth anti-shake time, the first judgment mode or the second judgment mode is used to determine the direction of the current. By setting the anti-shake time, frequent switching of working condition judgment results can be avoided.
  • the fourth anti-shake time may also be set as a plurality of task cycle times.
  • Fig. 4 shows a schematic diagram of logic for judging the direction of the bridge arm current according to the second exemplary embodiment of the present application.
  • Fig. 5 shows a schematic diagram of a bridge arm current direction according to a second exemplary embodiment of the present application.
  • the sampled value of the bridge arm current is compared with the set threshold value, so as to determine the working condition of the bridge arm current and the corresponding method of judging the current direction. That is, when the bridge arm current is in a low-load working condition, the low-load judgment method is adopted; when the bridge arm current is in a normal working condition, the normal judgment method is adopted.
  • the low load judging way includes a first judging way
  • the normal judging way includes a first judging way and a second judging way.
  • the anti-shake time T (see Figure 5) can also be set, so as to avoid frequent switching of judging methods.
  • the anti-shake time can be set as multiple task cycle times.
  • the direction of the bridge arm current is determined using the second judgment method, that is, the direction of the bridge arm current is determined according to the relationship between the sampled value of the bridge arm current and the threshold value.
  • the arm current sampling value is greater than or equal to the positive threshold Is1 (Ib ⁇ Is1)
  • the direction of the bridge arm current is the positive direction, and at this time it is the charging direction (see Figure 5)
  • the bridge arm current is less than or equal to the negative threshold Is2 (Ib ⁇ Is2)
  • the direction of the bridge arm current is the negative direction, which is the discharge direction at this time (see Figure 5).
  • the direction of the bridge arm current is determined using the first judgment method, that is, the current direction is periodically reversed, and the reversal result is used as the judged current direction.
  • the direction of the bridge arm current is changed every 0.5Ts, where Ts is the theoretical period of the bridge arm current.
  • Ts is the theoretical period of the bridge arm current.
  • the period of the bridge arm current is 20 ms, and the direction of the bridge arm current is changed every 10 ms.
  • a low-load judgment method is used to determine the direction of the bridge arm current.
  • the direction of the bridge arm current is determined by the first judgment method, that is, the direction of the current is reversed periodically, and the result of the reversal is used as the judged current direction.
  • the direction of the bridge arm current is changed every 0.5Ts, where Ts is the theoretical period of the bridge arm current.
  • Ts is the theoretical period of the bridge arm current.
  • the period of the bridge arm current is 20 ms, and the direction of the bridge arm current is changed every 10 ms.
  • Fig. 6 shows a flowchart of a method for judging the direction of a bridge arm current according to a third exemplary embodiment of the present application.
  • the method for judging the current direction of the bridge arm of the modular multilevel converter provided by the present application includes the following steps.
  • step S610 the collected current value of the bridge arm is compared with a set first positive threshold and a second negative threshold. Normally, when the bridge arm current value Ib of the converter is greater than or equal to the set first positive threshold Is1 or less than or equal to the set second negative threshold Is2, the converter is in a normal working condition (that is, Ib ⁇ Is1 or Ib ⁇ Is2); when the bridge arm current value Ib of the inverter is less than the set first threshold Is1 and greater than the set second negative threshold Is2 (that is, Is2 ⁇ Ib ⁇ Is1), the inverter is at low load condition.
  • step S620 when the current value is less than the first positive threshold and greater than the second negative threshold, a first judgment mode is used to determine the direction of the current; wherein the first judgment mode includes, the The positive or negative of the periodic variation of the voltage of the capacitor in the bridge arm is used as the direction of the current. That is, when the period variation is greater than zero, the bridge arm current is in a positive direction and is in a charging state; when the period variation is less than zero, the bridge arm current is in a negative direction and is in a discharging state. When the period variation is zero, keep the last judgment result.
  • the voltage Uc(n) of the capacitor may be the sum of the voltages of the capacitors of all sub-modules in the bridge arm, or the average voltage of the capacitors of all the sub-modules in the bridge arm.
  • the anti-shake time may also be set for the periodic variation of the voltage of the capacitor in the bridge arm.
  • the duration of the period variation of the voltage of the capacitor in the bridge arm is a positive value is not less than the first anti-shake time or the duration of the period variation is negative is not less than the second anti-shake time, the period variation Positive and negative as the direction of the current flow.
  • the first anti-shake time and the second anti-shake time may be equal or unequal, and specific settings may be made according to actual needs.
  • Fig. 7 shows a schematic diagram of the logic of the first judging mode according to the third exemplary embodiment of the present application
  • Fig. 8 shows a schematic diagram of the direction of bridge arm current in the first judging mode according to the third exemplary embodiment of the present application.
  • the judgment logic of the first judgment mode shown in FIG. 6 is as follows:
  • the sub-module capacitor voltage sum Uc(n) of the current cycle is compared with the sub-module capacitor voltage sum Uc(n-1) of the previous cycle to obtain the period variation ⁇ Uc of the sub-module capacitor voltage sum of the current cycle (n):
  • the variation trend of the sub-module capacitor voltage sum is judged. Specifically, the period variation ⁇ Uc(n) of the sum of sub-module capacitor voltages in the current period is compared with zero.
  • S750 it is judged whether the change amount of the sub-module capacitor voltage sum is greater than zero. Specifically, as shown in Figure 8, when the duration of the periodic variation of the capacitor voltage sum of the sub-module is greater than zero for longer than the first anti-shake time T1, the bridge arm current is judged to be in the positive direction and is in the charging state.
  • Fig. 9 shows a flowchart of a method for judging the direction of a bridge arm current according to a fourth exemplary embodiment of the present application.
  • the judging method shown in FIG. 6 may further include the following steps.
  • step S630 when the current value is greater than or equal to the first positive threshold or less than or equal to the second negative threshold, the direction of the current is determined using the first judgment mode or the second judgment mode ; Wherein, the second judgment mode includes taking the positive or negative of the current value as the direction of the current.
  • the bridge arm When the current value of the bridge arm is greater than or equal to the set first positive threshold or less than or equal to the set second negative threshold, the bridge arm is in a normal working condition.
  • the direction of the current can be determined according to the positive or negative of the collected current value.
  • the positive and negative of the periodic variation of the voltage of the capacitor in the bridge arm may also be used as the direction of the current. That is, when the period variation is greater than zero, the bridge arm current is in a positive direction and is in a charging state; when the period variation is less than zero, the bridge arm current is in a negative direction and is in a discharging state. When the period variation is zero, keep the last judgment result.
  • the voltage Uc(n) of the capacitor may be the sum of the voltages of the capacitors of all sub-modules in the bridge arm, or the average voltage of the capacitors of all the sub-modules in the bridge arm.
  • an anti-shake time may also be set for determining normal working conditions. For example, when the current value of the bridge arm is greater than or equal to the first positive threshold or less than or equal to the second negative threshold for a duration not less than the fourth anti-shake time, the first judgment mode or the second judgment mode is used to determine the direction of the current. By setting the anti-shake time, frequent switching of working condition judgment results can be avoided. According to an embodiment of the present application, the fourth anti-shake time can also be set as a plurality of task cycle times.
  • Fig. 10 shows a schematic diagram of judging the direction of bridge arm current according to the fourth exemplary embodiment of the present application
  • Fig. 11 shows a schematic diagram of the direction of bridge arm current according to the fourth exemplary embodiment of the present application.
  • the bridge arm current direction is determined according to the magnitude relationship between the bridge arm current sampling value and the threshold value, when the bridge arm current sampling value is greater than or equal to the positive threshold Is1 (Ib ⁇ Is1), The direction of the bridge arm current is the positive direction (see Figure 11); when the bridge arm current is less than or equal to the negative threshold Is2 (Ib ⁇ Is2), the bridge arm current direction is the negative direction (see Figure 11).
  • the current direction of the bridge arm is determined according to the periodic variation of the capacitor voltage of the internal sub-module of the bridge arm.
  • the periodic variation of the capacitor voltage is greater than zero, the direction of the bridge arm current is positive; when the periodic variation of the capacitor voltage is less than zero, the direction of the bridge arm current is negative.
  • a low-load judging method is used to determine the direction of the bridge arm current.
  • the current direction of the bridge arm is judged according to the periodic variation of the capacitor voltage of the internal sub-module of the bridge arm.
  • the periodic variation of the capacitor voltage is greater than zero, the direction of the bridge arm current is positive; when the periodic variation of the capacitor voltage is less than zero, the direction of the bridge arm current is negative.
  • a certain anti-shake time can be set in the above comparison.
  • Fig. 12 shows a schematic diagram of a modular multilevel converter control system according to an example embodiment of the present application.
  • a control system 2000 of a modular multilevel converter includes a converter 1000 , a measurement unit 1100 , a valve control system 1200 , and a protection system 1300 .
  • each bridge arm of the converter 1000 includes multiple sub-modules.
  • the measuring unit 1200 is used for measuring the current value of each bridge arm in the converter 1000 or the voltage value of the capacitance of each sub-module.
  • the valve control system 1300 is used for receiving the current value of the bridge arm or the voltage value of the capacitor measured by the measuring unit 1200 .
  • the inverter control and protection system 1300 is used to send the voltage reference wave of the bridge arm of the inverter to the valve control system.
  • the valve control system 1200 is an intermediate bridge between the converter control and protection system 1300 and the converter 1000, and is also used to generate the number of input sub-modules of each bridge arm and control the bridge arm of the converter according to the voltage reference wave modulation. input quantity, and judge the current direction of the bridge arm of the converter according to the current value or voltage value using the above judgment method, and then send a trigger command to the converter according to the current direction.
  • Fig. 13 shows a block diagram of electronic equipment used for judging the current direction of a bridge arm of a modular multilevel converter according to an exemplary embodiment of the present application.
  • an electronic device for judging the current direction of a bridge arm of a modular multilevel converter is also provided.
  • the control device 500 shown in FIG. 13 is only an example, and should not limit the functions and scope of use of this embodiment of the present application.
  • control device 500 takes the form of a general-purpose computing device.
  • Components of the control device 500 may include but not limited to: at least one processing unit 510, at least one storage unit 520, a bus 530 connecting different system components (including the storage unit 520 and the processing unit 510), and the like.
  • the storage unit 520 stores program codes, which can be executed by the processing unit 510, so that the processing unit 510 executes the method for judging the direction of the bridge arm current described in this specification according to the above-mentioned embodiments of the present application.
  • the storage unit 520 may include a readable medium in the form of a volatile storage unit, such as a random access storage unit (RAM) 5201 and/or a cache storage unit 5202 , and may further include a read-only storage unit (ROM) 5203 .
  • RAM random access storage unit
  • ROM read-only storage unit
  • Storage unit 520 may also include a program/utility 5204 having a set (at least one) of program modules 5205, such program modules 5205 including but not limited to: an operating system, one or more application programs, other program modules, and program data, Implementations of networked environments may be included in each or some combination of these examples.
  • Bus 530 may represent one or more of several types of bus structures, including a memory unit bus or memory unit controller, a peripheral bus, an accelerated graphics port, a processing unit, or a local area using any of a variety of bus structures. bus.
  • the electronic device 500 can also communicate with one or more external devices 5001 (such as touch screens, keyboards, pointing devices, Bluetooth devices, etc.), and can also communicate with one or more devices that enable the user to interact with the electronic device 500, and/or Or communicate with any device (eg, router, modem, etc.) that enables the electronic device 500 to communicate with one or more other computing devices. Such communication may occur through input/output (I/O) interface 550 .
  • the electronic device 500 can also communicate with one or more networks (such as a local area network (LAN), a wide area network (WAN) and/or a public network such as the Internet) through the network adapter 560 .
  • the network adapter 560 can communicate with other modules of the electronic device 500 through the bus 530 .
  • other hardware and/or software modules may be used in conjunction with electronic device 500, including but not limited to: microcode, device drivers, redundant processing units, external disk drive arrays, RAID systems, tape drives And data backup storage system, etc.
  • a computer-readable medium on which a computer program is stored, and when the computer program is executed by a processor, the above judging method is implemented.
  • the method for judging the current direction of the bridge arm of the modular multilevel converter provided by this application adopts a fixed cycle flip or judges the direction of the bridge arm current according to the change of the capacitor voltage of the sub-module inside the bridge arm when the bridge arm current is small, which can avoid The current sampling distortion problem of the bridge arm caused by factors such as current sampling zero drift under the condition of small current.
  • This judgment method can accurately judge the direction of the bridge arm current under any working condition, especially under the low-load operation condition with small bridge arm current, and provide accurate instructions for the sub-module input control strategy of the valve control system. To ensure the safe and reliable operation of the system to the maximum extent.

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Abstract

本申请提供一种模块化多电平换流器桥臂电流方向的判断方法、控制系统、电子设备及计算机存储介质。所述判断方法包括：采用第一判断模式确定所述电流的方向；其中，所述第一判断模式包括，将所述桥臂中电容的电压的周期变化量的正负作为所述电流的方向；或，将所述电流的方向按照固定周期进行翻转，并将所述翻转的结果作为所述电流的方向。在桥臂电流较小时采用根据桥臂内部子模块电容电压的变化或固定周期翻转来判断桥臂电流方向，可以避免小电流情况下电流采样零漂等因素造成的桥臂电流采样失真问题。

Description

模块化多电平换流器桥臂电流方向的判断方法及控制系统 技术领域
本申请涉及电力电子技术领域，具体涉及一种模块化多电平换流器桥臂电流方向的判断方法、控制系统、电子设备及计算机可读介质。
背景技术
模块化多电平换流器(modular multilevel converter，MMC)广泛应用于柔性直流输电工程、静止同步补偿器和低频输电等电力电子系统领域。模块化多电平换流器每一个桥臂均由N个子模块串联而组成。换流器子模块投入的数量一般由阀控系统来控制。阀控系统是换流器控制保护系统和换流器子模块之间的中间桥梁。阀控系统接收换流器控制保护系统的控制指令并将其进行调制，得到各换流器桥臂需要投入的子模块个数，最终选取合适的子模块进行投入。
在选择需要投入的子模块时，总体原则是在桥臂充电(即，桥臂电流方向为正)时选择电压较小的子模块投入、在桥臂放电(即，桥臂电流方向为负)时选择电压较大的子模块投入，从而实现整个桥臂内部子模块电压的均衡。因此，桥臂电流方向的判断是阀控系统的关键功能之一。准确有效的桥臂电流方向判断策略对换流器子模块的电压控制和子模块的开关频率抑制均有重要作用。
目前，桥臂电流方向通常通过桥臂电流采样值的正负来进行判断。当桥臂电流采样值较小时，由于采样零漂和噪声等因素，这种判断方法存在桥臂电流较小时方向判断发生错误，造成子模块投入紊乱，从而导致子模块过压、高频投入等问题，危害系统运行安全。此外，在小电流工况下通过设定防抖时间来判断桥臂电流方向的方法中，由于采样误差等因素，桥臂电流在零附近失真。因此，仅通过防抖时间不能准确判断真实的电流方向。
发明内容
基于此，为了解决传统的电流方向判断方法在电流采样值较小时存在电流方向判断错误的问题，本申请提供了一种模块化多电平换流器桥臂电流方向的判断方法，包括：
采用第一判断模式确定所述电流的方向；其中，所述第一判断模式包括，
将所述桥臂中电容的电压的周期变化量的正负作为所述电流的方向；或
将所述电流的方向按照固定周期进行翻转，并将所述翻转的结果作为所述电流的方向。
根据一些实施例，在采用第一判断模式确定所述电流的方向之前，所述判断方法还包括：将采集的所述桥臂的电流值与设定的第一正阈值和第二负阈值进行比较；其中，当所述电流值小于所述第一正阈值且大于所述第二负阈值时，采用所述第一判断模式确定所述电流的方向。
根据本申请的一些实施例，当所述桥臂中电容的电压的周期变化量为正值的持续时间不小于第一防抖时间或者所述周期变化量为负值的持续时间不小于第二防抖时间时，将所述周期变化量的正负作为所述电流的方向。
根据本申请的一些实施例，所述周期变化量包括：
当前周期所述桥臂中电容的电压与上一周期所述桥臂中电容的电压的差值。
根据本申请的一些实施例，所述电容的电压包括：
所述桥臂中所有子模块的电容的电压之和；或
所述桥臂中所有子模块的电容的平均电压。
根据本申请的一些实施例，所述将所述电流按照固定周期进行翻转，包括：
每间隔第一周期，变换一次所述桥臂的电流方向。
根据本申请的一些实施例，所述第一周期包括：所述桥臂的电流周期 的N倍或N分之一，N为大于等于1的自然数。
根据本申请的一些实施例，当所述电流值小于所述第一正阈值且大于所述第二负阈值的持续时间不小于第三防抖时间时，采用所述第一判断模式确定所述电流的方向。
根据本申请的一些实施例，所述判断方法，还包括：
当所述电流值大于等于所述第一正阈值或者小于等于所述第二负阈值时，采用所述第一判断模式或第二判断模式确定所述电流的方向；其中，所述第二判断模式包括，
将所述电流值的正负作为所述电流的方向。
根据本申请的一些实施例，当所述电流值大于等于所述第一正阈值或者小于等于所述第二负阈值的持续时间不小于第四防抖时间时，采用所述第一判断模式或所述第二判断模式确定所述电流的方向。
根据本申请的第一方面，提供一种模块化多电平换流器的控制系统，包括，
换流器；
测量单元，用于测量所述换流器中各个桥臂的电流值或各个子模块的电容的电压值；
阀控系统，用于接收所述测量单元测量的所述桥臂的电流值或所述电容的电压值；
换流器控制保护系统，用于向所述阀控系统发送所述换流器的桥臂的电压参考波；
所述阀控系统，还用于根据所述电压参考波控制所述换流器的桥臂的投入数量，并根据所述电流值或电压值采用上述判断方法判断所述换流器的桥臂的电流方向，进而根据所述电流方向向所述换流器发送触发命令。
根据本申请的另一方面，提供一种，包括：
一个或多个处理器；
存储装置，用于存储一个或多个程序；
当所述一个或多个程序被所述一个或多个处理器执行，使得所述一个或多个处理器实现上述判断方法。
根据本申请的另一方面，还提供一种计算机可读介质，其上存储有 计算机程序，所述程序被处理器执行时实现上述判断方法。
本申请提供的模块化多电平换流器的桥臂电流方向判断方法，在桥臂电流较大时根据桥臂电流采样值与阈值的大小关系来判断桥臂电流方向；在桥臂电流较小时采用固定周期翻转或根据桥臂内部子模块电容电压的变化来判断桥臂电流方向，可以避免小电流情况下电流采样零漂等因素造成的桥臂电流采样失真问题。该判断方法可以在任何工况下、特别是桥臂电流较小的低载运行工况下准确判断桥臂电流方向，为阀控系统的子模块投入控制策略提供准确指令，在全工况条件下最大限度保证系统安全可靠运行。
本申请的附加方面和优点将在下面的描述中部分给出，部分将从下面的描述中变得明显，或通过本申请的实践了解到。
附图说明
为了更清楚地说明本申请实施例中的技术方案，下面将对实施例描述中所需要使用的附图作简单地介绍，显而易见地，下面描述中的附图仅仅是本申请的一些实施例，对于本领域普通技术人员来讲，还可以根据这些附图获得其他的附图，而并不超出本申请要求保护的范围。
图1示出了根据本申请示例实施例的模块化多电平换流器一个桥臂的示意图；
图2示出了根据本申请第一示例实施例的桥臂电流方向的判断方法流程图；
图3示出了根据本申请第二示例实施例的桥臂电流方向的判断方法流程图；
图4示出了根据本申请第二示例实施例的桥臂电流方向的判断逻辑示意图；
图5示出了根据本申请第二示例实施例的桥臂电流方向示意图；
图6示出了根据本申请第三示例实施例的桥臂电流方向的判断方法流程图；
图7示出了根据本申请第三示例实施例的第一判断模式的逻辑示 意图；
图8示出了根据本申请第三示例实施例的第一判断模式下的桥臂电流方向示意图；
图9示出了根据本申请第四示例实施例的桥臂电流方向的判断方法流程图；
图10示出了根据本申请第四示例实施例的桥臂电流方向的判断逻辑示意图；
图11示出了根据本申请第四示例实施例的桥臂电流方向示意图；
图12示出了根据本申请示例实施例的模块化多电平换流器控制系统的示意图；
图13示出根据本申请示例实施例的用于模块化多电平换流器桥臂电流方向判断的电子设备组成框图。
具体实施方式
下面将参考附图更全面地描述示例实施例。然而，示例实施例能以多种形式实施，且不应被理解为限于在此阐述的实施例。提供这些实施例是为使得本申请更全面和完整，并将示例实施例的构思全面地传达给本领域的技术人员。在图中相同的附图标记表示相同或类似的部分，因而将省略对它们的重复描述。
此外，所描述的特征、结构或特性可以以任何合适的方式结合在一个或更多实施例中。在下面的描述中，提供许多具体细节从而给出对本申请的实施例的充分理解。然而，本领域技术人员将意识到，可以实践本申请的技术方案而没有特定细节中的一个或更多，或者可以采用其它的方法、组元、装置、步骤等。在其它情况下，不详细示出或描述公知方法、装置、实现或者操作以避免模糊本申请的各方面。
应理解，虽然本文中可能使用术语第一、第二等来描述各种组件，但这些组件不应受这些术语限制。这些术语乃用以区分一组件与另一组件。因此，下文论述的第一组件可称为第二组件而不偏离本申请概念的 教示。如本文中所使用，术语“及/或”包括相关联的列出项目中的任一个及一或多者的所有组合。
本领域技术人员可以理解，附图只是示例实施例的示意图，可能不是按比例的。附图中的模块或流程并不一定是实施本申请所必须的，因此不能用于限制本申请的保护范围。
图1示出了根据本申请示例实施例的模块化多电平换流器一个桥臂的示意图。
根据本申请的示例实施例，如图1所示，模块化多电平换流器1000的一个桥臂100由N个子模块110串联组成，例如由1号子模块、2号子模块、3号子模块、……、N号子模块彼此串联连接。每一个子模块110的拓扑结构可以是半桥、全桥、类全桥等多种形式。其中，半桥型子模块110包括直流电容111以及与其并联的由IGBT1、IGBT2串联构成的电路。每一个IGBT与一个反向二极管112并联。
对于图1中所述的换流器的桥臂，为了解决传统的电流方向判断方法在电流采样值较小时存在电流方向判断错误的问题，本申请提供一种电流方向判断方法，根据桥臂电流采样值来确定桥臂所处的工况，进而选择不同的判断方式来进行判断，从而避免电流采样值较小时的电流方向判断错误问题，即当桥臂电流值较大(电流绝对值大于电流峰值的0.00001～1倍，例如千分之五，具体可根据实际情况进行调整)时，判断处于正常工况，根据桥臂电流采样值与阈值比较得到当前的桥臂电流方向；当桥臂电流值较小(电流绝对值小于电流峰值的0.00001～1倍，例如千分之五，具体可根据实际情况进行调整)时，经过判断进入低载工况后，采用固定周期翻转、采用子模块电容电压判据等判断方法，来得到桥臂电流方向。
根据另一些实施例，不对桥臂电流的工况进行判断，在任意电流值，都可以采用第一判断模式确定桥臂电流的方法。
在具体实施例中，可选地，第一判断模式包括将桥臂中电容的电压的周期变化量的正负作为电流的方向。也即，当周期变化量大于零时，桥臂电流为正方向，处于充电状态；当周期变化量小于零时，桥臂电流为负方向，处于放电状态。当周期变化量为零时，保持上一次的判断结 果。根据一些实施例，周期变化量为当前周期桥臂中电容的电压Uc(n)与上一周期桥臂中电容的电压Uc(n-1)的差值ΔUc(n)：ΔUc(n)＝Uc(n)-Uc(n-1)。其中，电容的电压Uc(n)可以是桥臂中所有子模块的电容的电压之和，也可以是桥臂中所有子模块的电容的平均电压。根据本申请的一些实施例，还可以对桥臂中电容的电压的周期变化量设定防抖时间。例如，当桥臂中电容的电压的周期变化量为正值的持续时间不小于第一防抖时间或者周期变化量为负值的持续时间不小于第二防抖时间时，将周期变化量的正负作为电流的方向。第一防抖时间和第二防抖时间可以相等，也可以不相等，具体的设定可以根据实际需求来进行。
在另一些具体实施例中，可选地，第一判断模式包括将桥臂中电容的电压的周期变化量的正负作为电流的方向。例如，每间隔第一周期，变换一次所述桥臂的电流方向。经过周期翻转后，将生成的桥臂电流方向作为判断结果。根据本申请的实施例，第一周期可以是桥臂的电流周期的N倍或N分之一，N为大于等于1的自然数。例如，第一周期可以为0.5Ts，其中Ts为桥臂电流的理论周期。对于传统的柔性直流输电的模块化多电平换流器而言，桥臂电流的周期为20ms，则可以每隔10ms变换一次桥臂电流方向。
图2示出了根据本申请第一示例实施例的桥臂电流方向的判断方法流程图。
如图2所示，根据本申请的第一示例实施例，本申请提供的模块化多电平换流器的桥臂电流方向的判断方法，包括以下步骤。
在步骤S210，将采集的所述桥臂的电流值与设定的第一正阈值和第二负阈值进行比较。通常情况下，当换流器的桥臂电流值Ib大于等于设定的第一正阈值Is1或者小于等于设定的第二负阈值Is2时，换流器处于正常工况(即，Ib≥Is1或Ib≤Is2)；当换流器的桥臂电流值Ib小于设定的第一阈值Is1且大于设定的第二负阈值Is2时(即，Is2<Ib<Is1)，换流器处于低载工况。根据本申请的一些实施例，用于判断换流器工况的第一正阈值可以设定为桥臂电流正峰值的0.00001～1倍(例如千分之五)，第二负阈值也可以设定为桥臂电流负峰值的0.00001～1倍(例如，千分之五)，本申请对此不作限制。
在步骤S220，当所述电流值小于所述第一正阈值且大于所述第二负阈值时，采用第一判断模式确定所述电流的方向；其中，所述第一判断模式包括，控制所述电流的方向按照固定周期进行翻转，并将所述翻转的结果作为所述电流的方向。
当采集的桥臂的电流值小于第一正阈值且大于第二负阈值时，则可以判定换流器处于低载工况。此时，可以控制桥臂电流按照固定周期进行翻转，例如，每间隔第一周期，变换一次所述桥臂的电流方向。经过周期翻转后，将生成的桥臂电流方向作为判断结果。
根据本申请的一些实施例，第一周期可以是所述桥臂的电流周期的N倍或N分之一，N为大于等于1的自然数。例如，第一周期可以为0.5Ts，其中Ts为桥臂电流的理论周期。对于传统的柔性直流输电的模块化多电平换流器而言，桥臂电流的周期为20ms，则可以每隔10ms变换一次桥臂电流方向。
根据本申请的一些实施例，还可以为低载工况的判定设定防抖时间。例如，当桥臂的电流值小于第一正阈值且大于第二负阈值的持续时间不小于设定的第三防抖时间时，采用第一判断模式确定所述电流的方向。通过设定防抖时间，可以避免工况判断结果的频繁切换。根据本申请的实施例，第三防抖时间可以设定为多个任务周期时间。
图3示出了根据本申请第二示例实施例的桥臂电流方向的判断方法流程图。
根据本申请的另一实施例，图2中所示的判断方法还可以包括以下步骤。
在步骤S230，当所述电流值大于等于所述第一正阈值或者小于等于所述第二负阈值时，采用第一判断模式或第二判断模式确定所述电流的方向；其中，所述第二判断模式包括，将所述电流值的正负作为所述电流的方向。
桥臂的电流值大于等于设定的第一正阈值或者小于等于设定的第二负阈值时，桥臂处于正常工况。根据一些实施例，此时可以通过采集的电流值的正负来判断电流方向。根据另一些实施例，此时也可以通过控制电流的方向按照固定周期进行翻转，并将翻转的结果作为电流的方向。 例如，每间隔第二周期，变换一次桥臂的电流方向。经过周期翻转后，将生成的桥臂电流方向作为判断结果。其中，第二周期和第一周期可以相同，也可以不同。
根据本申请的一些实施例，还可以为正常工况的判定设定防抖时间。例如，当桥臂的电流值大于等于第一正阈值或者小于等于第二负阈值的持续时间不小于第四防抖时间时，采用第一判断模式或第二判断模式确定所述电流的方向。通过设定防抖时间，可以避免工况判断结果的频繁切换。根据本申请的实施例，第四防抖时间也可以设定为多个任务周期时间。
图4示出了根据本申请第二示例实施例的桥臂电流方向的判断逻辑示意图。图5示出了根据本申请第二示例实施例的桥臂电流方向示意图。
当采用图3所示的电流方向的判断方法进行桥臂电流方向判断时，其判断过程的逻辑如图4所示。
在S410中，开始每个任务周期的桥臂电流方向判断。
在S420中，比较桥臂电流的采样值和设定阈值，从而确定桥臂电流所处的工况和对应的电流方向的判断方式。即，桥臂电流处于低载工况时，采用低载判断方式；桥臂电流处于正常工况时，采用正常判断方式。其中，低载判断方式包括第一判断方式，正常判断方式包括第一判断方式和第二判断方式。
在正常工况、低载工况的判断过程中，还可以设定防抖时间T(参见图5)，从而避免判断方式的频繁切换。防抖时间可以设定为多个任务周期时间。
在S430中，根据电流采样值的判断结果，确定是否采用正常判断方式。参见图5，当桥臂电流大于等于正阈值Is1(Ib≥Is1)或桥臂电流小于等于负阈值Is2(Ib≤Is2)时，则采用正常判断方式；当桥臂电流采样值大于负阈值Is2且小于正阈值Is1(Is2<Ib<Is1)时，则采用低载判断方式。
在S440中，采用正常判断方式确定桥臂电流的方向。
在具体实施例中，可选地，在步骤S440中，采用第二判断方式确 定桥臂电流的方向，也即，根据桥臂电流采样值与阈值的大小关系来判断桥臂电流方向，当桥臂电流采样值大于等于正阈值Is1(Ib≥Is1)时，桥臂电流方向为正方向，此时为充电方向(参见图5)；当桥臂电流小于等于负阈值Is2(Ib≤Is2)时，桥臂电流方向为负方向，此时为放电方向(参见图5)。
在具体实施例中，可选地，在步骤S440中，采用第一判断方式确定桥臂电流的方向，也即，对电流方向进行周期翻转，并将翻转结果作为判断的电流方向。例如，每隔0.5Ts改变一次桥臂电流方向，其中Ts为桥臂电流的理论周期。对于传统的柔性直流输电的模块化多电平变换器，桥臂电流的周期为20ms，则每隔10ms变换一次桥臂电流方向。
在S450中，采用低载判断方式确定桥臂电流方向。在低载工况下，采用第一判断方式确定桥臂电流的方向，也即，对电流方向进行周期翻转，并将翻转结果作为判断的电流方向。例如，每隔0.5Ts改变一次桥臂电流方向，其中Ts为桥臂电流的理论周期。对于传统的柔性直流输电的模块化多电平变换器，桥臂电流的周期为20ms，则每隔10ms变换一次桥臂电流方向。
在S460中，生成桥臂电流方向判断结果。
在S470中，结束当前运行的桥臂电流方向判断方法。
图6示出了根据本申请第三示例实施例的桥臂电流方向的判断方法流程图。
如图6所示，根据本申请的第三示例实施例，本申请提供的模块化多电平换流器的桥臂电流方向的判断方法，包括以下步骤。
在步骤S610，将采集的所述桥臂的电流值与设定的第一正阈值和第二负阈值进行比较。通常情况下，当换流器的桥臂电流值Ib大于等于设定的第一正阈值Is1或者小于等于设定的第二负阈值Is2时，换流器处于正常工况(即，Ib≥Is1或Ib≤Is2)；当换流器的桥臂电流值Ib小于设定的第一阈值Is1且大于设定的第二负阈值Is2时(即，Is2<Ib<Is1)，换流器处于低载工况。
在步骤S620，当所述电流值小于所述第一正阈值且大于所述第二负阈值时，采用第一判断模式确定所述电流的方向；其中，所述第一判断 模式包括，将所述桥臂中电容的电压的周期变化量的正负作为所述电流的方向。即，当周期变化量大于零时，桥臂电流为正方向，处于充电状态；当周期变化量小于零时，桥臂电流为负方向，处于放电状态。当周期变化量为零时，保持上一次的判断结果。
根据本申请的一些实施例，所述周期变化量为当前周期所述桥臂中电容的电压Uc(n)与上一周期所述桥臂中电容的电压Uc(n-1)的差值ΔUc(n)：ΔUc(n)＝Uc(n)-Uc(n-1)。其中，电容的电压Uc(n)可以是桥臂中所有子模块的电容的电压之和，也可以是桥臂中所有子模块的电容的平均电压。
根据本申请的一些实施例，还可以对桥臂中电容的电压的周期变化量设定防抖时间。例如，当桥臂中电容的电压的周期变化量为正值的持续时间不小于第一防抖时间或者周期变化量为负值的持续时间不小于第二防抖时间时，将周期变化量的正负作为所述电流的方向。第一防抖时间和第二防抖时间可以相等，也可以不相等，具体的设定可以根据实际需求来进行。
图7示出了根据本申请第三示例实施例的第一判断模式的逻辑示意图；图8示出了根据本申请第三示例实施例的第一判断模式下的桥臂电流方向示意图。
图6中所示的第一判断模式的判断逻辑如下：
在S710中，开始低载工况下每个任务周期的桥臂电流方向判断。
在S720中，对桥臂内子模块的电容电压进行求和，计算并记录当前周期的子模块电容电压和Uc(n)。
在S730中，将当前周期的子模块电容电压和Uc(n)与上一周期的子模块电容电压和Uc(n-1)作差，得到当前周期的子模块电容电压和的周期变化量ΔUc(n)：
ΔUc(n)＝Uc(n)-Uc(n-1)
在S740中，对子模块电容电压和的变化趋势进行判断。具体地，将当前周期的子模块电容电压和的周期变化量ΔUc(n)与零进行比较。
在S750中，对子模块电容电压和的变化量是否大于零的情况进行判断。具体地，如图8所示，当子模块电容电压和的周期变化量大于零的持续时 间大于第一防抖时间T1，则桥臂电流判断为正方向，处于充电状态。
在S760中，对子模块电容电压和变化量是否小于零的情况进行判断。具体地，当子模块电容电压和的周期变化量小于零的持续时间大于第二防抖时间T2，则桥臂电流判断为负方向，处于放电状态。
在S770中，生成桥臂电流方向判断结果。
在S780中，结束当前运行的桥臂电流方向判断方法。
图9示出了根据本申请第四示例实施例的桥臂电流方向的判断方法流程图。
根据本申请的另一实施例，图6中所示的判断方法还可以包括以下步骤。
如图9所示，在步骤S630，当所述电流值大于等于所述第一正阈值或者小于等于所述第二负阈值时，采用第一判断模式或第二判断模式确定所述电流的方向；其中，所述第二判断模式包括，将所述电流值的正负作为所述电流的方向。
桥臂的电流值大于等于设定的第一正阈值或者小于等于设定的第二负阈值时，桥臂处于正常工况。根据一些实施例，此时可以通过采集的电流值的正负来判断电流方向。根据另一些实施例，也可以采用将桥臂中电容的电压的周期变化量的正负作为电流的方向。即，当周期变化量大于零时，桥臂电流为正方向，处于充电状态；当周期变化量小于零时，桥臂电流为负方向，处于放电状态。当周期变化量为零时，保持上一次的判断结果。
根据本申请的一些实施例，周期变化量为当前周期桥臂中电容的电压Uc(n)与上一周期所述桥臂中电容的电压Uc(n-1)的差值ΔUc(n)：ΔUc(n)＝Uc(n)-Uc(n-1)。其中，电容的电压Uc(n)可以是桥臂中所有子模块的电容的电压之和，也可以是桥臂中所有子模块的电容的平均电压。
根据本申请的一些实施例，还可以为正常工况的判定设定防抖时间。例如，当桥臂的电流值大于等于第一正阈值或者小于等于第二负阈值的持续时间不小于第四防抖时间时，采用第一判断模式或第二判断模式确定所述电流的方向。通过设定防抖时间，可以避免工况判断结果的频繁切换。根据本申请的实施例，第四防抖时间也可以设定为多个任务 周期时间。
图10示出了根据本申请第四示例实施例的桥臂电流方向的判断逻辑示意图；图11示出了根据本申请第四示例实施例的桥臂电流方向示意图。
当采用图9所示的电流方向的判断方法进行桥臂电流方向判断时，其判断过程的逻辑如图10所示。
在S910中，开始每个任务周期的桥臂电流方向判断。
在S920中，比较桥臂电流的采样值和设定阈值，从而确定桥臂电流所处的工况和对应的电流方向的判断方式。即，桥臂电流处于低载工况时，采用低载判断方式(第一判断方式)；桥臂电流处于正常工况时，采用正常判断方式(第二判断方式)。在正常工况、低载工况的判断过程中，还可以设定防抖时间T(参见图11)，从而避免判断方式的频繁切换。防抖时间可以设定为多个任务周期时间。
在S930中，根据电流采样值的判断结果，确定是否采用正常判断方式。参见图10，当桥臂电流大于等于正阈值Is1(Ib≥Is1)或桥臂电流小于等于负阈值Is2(Ib≤Is2)时，则采用正常判断方式；当桥臂电流采样值大于负阈值Is2且小于正阈值Is1(Is2<Ib<Is1)时，则采用低载判断方式。
在S940中，采用正常判断方式确定桥臂电流的方向。
在具体实施例中，可选地，在S940中，根据桥臂电流采样值与阈值的大小关系来判断桥臂电流方向，当桥臂电流采样值大于等于正阈值Is1(Ib≥Is1)时，桥臂电流方向为正方向(参见图11)；当桥臂电流小于等于负阈值Is2(Ib≤Is2)时，桥臂电流方向为负方向(参见图11)。
在具体实施例中，可选地，在S940中，根据桥臂内部子模块的电容电压的周期变化量来判断桥臂电流方向。当电容电压的周期变化量大于零时，桥臂电流方向为正方向；当电容电压的周期变化量小于零时，桥臂电流方向为负方向。
在S950中，采用低载判断方式确定桥臂电流方向。在低载工况下，根据桥臂内部子模块的电容电压的周期变化量来判断桥臂电流方向。当电容电压的周期变化量大于零时，桥臂电流方向为正方向；当电容电压的周 期变化量小于零时，桥臂电流方向为负方向。为了避免桥臂电流方向的频繁变化，可以在上述比较中设置一定的防抖时间。
在S960中，生成桥臂电流方向判断结果。
在S970中，结束当前运行的桥臂电流方向判断方法。
图12示出了根据本申请示例实施例的模块化多电平换流器控制系统的示意图。
根据本申请的另一方面，还提供一种模块化多电平换流器的控制系统2000。参见图12，控制系统2000包括换流器1000、测量单元1100、阀控系统1200、保护系统1300。其中，换流器1000每一个桥臂包括多个子模块。测量单元1200用于测量换流器1000中各个桥臂的电流值或各个子模块的电容的电压值。阀控系统1300用于接收测量单元1200测量的桥臂的电流值或电容的电压值。换流器控制保护系统1300用于向阀控系统发送换流器的桥臂的电压参考波。阀控系统1200是换流器控制保护系统1300和换流器1000之间的中间桥梁，还用于根据所述电压参考波调制生成各桥臂投入子模块个数、控制换流器的桥臂的投入数量，并根据电流值或电压值采用上述判断方法判断换流器的桥臂的电流方向，进而根据电流方向向换流器发送触发命令。
图13示出根据本申请示例实施例的用于模块化多电平换流器桥臂电流方向判断的电子设备组成框图。
根据本申请的另一方面，还提供一种用于模块化多电平换流器桥臂电流方向判断的电子设备。图13显示的控制设备500仅仅是一个示例，不应对本申请实施例的功能和使用范围带来任何限制。
如图13所示，控制设备500以通用计算设备的形式表现。控制设备500的组件可以包括但不限于：至少一个处理单元510、至少一个存储单元520、连接不同系统组件(包括存储单元520和处理单元510)的总线530等。
存储单元520存储有程序代码，程序代码可以被处理单元510执行，使得处理单元510执行本说明书描述的根据本申请上述各实施例的桥臂电流方向判断方法。
存储单元520可以包括易失性存储单元形式的可读介质，例如随机 存取存储单元(RAM)5201和/或高速缓存存储单元5202，还可以进一步包括只读存储单元(ROM)5203。
存储单元520还可以包括具有一组(至少一个)程序模块5205的程序/实用工具5204，这样的程序模块5205包括但不限于：操作系统、一个或者多个应用程序、其它程序模块以及程序数据，这些示例中的每一个或某种组合中可能包括网络环境的实现。
总线530可以为表示几类总线结构中的一种或多种，包括存储单元总线或者存储单元控制器、外围总线、图形加速端口、处理单元或者使用多种总线结构中的任意总线结构的局域总线。
电子设备500也可以与一个或多个外部设备5001(例如触摸屏、键盘、指向设备、蓝牙设备等)通信，还可与一个或者多个使得用户能与该电子设备500交互的设备通信，和/或与使得该电子设备500能与一个或多个其它计算设备进行通信的任何设备(例如路由器、调制解调器等等)通信。这种通信可以通过输入/输出(I/O)接口550进行。并且，电子设备500还可以通过网络适配器560与一个或者多个网络(例如局域网(LAN)，广域网(WAN)和/或公共网络，例如因特网)通信。网络适配器560可以通过总线530与电子设备500的其它模块通信。应当明白，尽管图中未示出，可以结合电子设备500使用其它硬件和/或软件模块，包括但不限于：微代码、设备驱动器、冗余处理单元、外部磁盘驱动阵列、RAID系统、磁带驱动器以及数据备份存储系统等。
根据本申请的另一方面，还提供一种计算机可读介质，其上存储有计算机程序，所述计算机程序被处理器执行时实现上述的判断方法。
本申请提供的模块化多电平换流器的桥臂电流方向判断方法，在桥臂电流较小时采用固定周期翻转或根据桥臂内部子模块电容电压的变化来判断桥臂电流方向，可以避免小电流情况下电流采样零漂等因素造成的桥臂电流采样失真问题。该判断方法可以在任何工况下、特别是桥臂电流较小的低载运行工况下准确判断桥臂电流方向，为阀控系统的子模块投入控制策略提供准确指令，在全工况条件下最大限度保证系统安全可靠运行。
以上对本申请实施例进行了详细介绍，本文中应用了具体个例对本 申请的原理及实施方式进行了阐述，以上实施例的说明仅用于帮助理解本申请的方法及其核心思想。同时，本领域技术人员依据本申请的思想，基于本申请的具体实施方式及应用范围上做出的改变或变形之处，都属于本申请保护的范围。综上所述，本说明书内容不应理解为对本申请的限制。

Claims (13)

  1. 一种模块化多电平换流器桥臂电流方向的判断方法，其特征在于，包括：
    采用第一判断模式确定所述电流的方向；
    其中，所述第一判断模式包括，
    将所述桥臂中电容的电压的周期变化量的正负作为所述电流的方向；或
    将所述电流的方向按照固定周期进行翻转，并将所述翻转的结果作为所述电流的方向。
  2. 根据权利要求1所述的判断方法，其特征在于，在采用第一判断模式确定所述电流的方向之前，所述判断方法还包括：
    将采集的所述桥臂的电流值与设定的第一正阈值和第二负阈值进行比较；
    其中，当所述电流值小于所述第一正阈值且大于所述第二负阈值时，采用所述第一判断模式确定所述电流的方向。
  3. 根据权利要求1所述的判断方法，其特征在于，当所述桥臂中电容的电压的周期变化量为正值的持续时间不小于第一防抖时间或者所述周期变化量为负值的持续时间不小于第二防抖时间时，将所述周期变化量的正负作为所述电流的方向。
  4. 根据权利要求1所述的判断方法，其特征在于，所述周期变化量包括：
    当前周期所述桥臂中电容的电压与上一周期所述桥臂中电容的电压的差值。
  5. 根据权利要求4所述的判断方法，其特征在于，所述电容的电压包括：
    所述桥臂中所有子模块的电容的电压之和；或
    所述桥臂中所有子模块的电容的平均电压。
  6. 根据权利要求1所述的判断方法，其特征在于，所述将所述电流按照固定周期进行翻转，包括：
    每间隔第一周期，变换一次所述桥臂的电流方向。
  7. 根据权利要求6所述的判断方法，其特征在于，所述第一周期包括：
    所述桥臂的电流周期的N倍或N分之一，N为大于等于1的自然数。
  8. 根据权利要求2所述的判断方法，其特征在于，当所述电流值小于所述第一正阈值且大于所述第二负阈值的持续时间不小于第三防抖时间时，采用所述第一判断模式确定所述电流的方向。
  9. 根据权利要求2所述的判断方法，其特征在于，还包括：
    当所述电流值大于等于所述第一正阈值或者小于等于所述第二负阈值时，采用所述第一判断模式或第二判断模式确定所述电流的方向；
    其中，所述第二判断模式包括，将所述电流值的正负作为所述电流的方向。
  10. 根据权利要求9所述的判断方法，其特征在于，当所述电流值大于等于所述第一正阈值或者小于等于所述第二负阈值的持续时间不小于第四防抖时间时，采用所述第一判断模式或第二判断模式确定所述电流的方向。
  11. 一种模块化多电平换流器的控制系统，包括，
    换流器；
    测量单元，用于测量所述换流器中各个桥臂的电流值或各个子模块的电容的电压值；
    阀控系统，用于接收所述测量单元测量的所述桥臂的电流值或所述电 容的电压值；
    换流器控制保护系统，用于向所述阀控系统发送所述换流器的桥臂的电压参考波；
    其特征在于，
    所述阀控系统，还用于根据所述电压参考波控制所述换流器的桥臂的投入数量，并根据所述电流值或电压值采用权利要求1-10中任一项所述的判断方法判断所述换流器的桥臂的电流方向，进而根据所述电流方向向所述换流器发送触发命令。
  12. 一种电子设备，其特征在于，包括：
    一个或多个处理器；
    存储装置，用于存储一个或多个程序；
    当所述一个或多个程序被所述一个或多个处理器执行，使得所述一个或多个处理器实现权利要求1-10中任一项所述的判断方法。
  13. 一种计算机可读介质，其上存储有计算机程序，其特征在于，所述程序被处理器执行时实现权利要求1-10中任一项所述的判断方法。
PCT/CN2023/071017 2022-01-07 2023-01-06 模块化多电平换流器桥臂电流方向的判断方法及控制系统 WO2023131300A1 (zh)

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Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPH0698557A (ja) * 1992-09-14 1994-04-08 Fuji Electric Co Ltd パルス幅変調制御インバータの制御回路
JP2005184905A (ja) * 2003-12-17 2005-07-07 Mitsubishi Electric Corp インバータ装置
CN101820231A (zh) * 2010-04-15 2010-09-01 浙江大学 用于变频器的电流过零检测及死区补偿方法
CN103901257A (zh) * 2014-03-04 2014-07-02 国家电网公司 模块化多电平换流器桥臂电流方向测量装置及判断方法
CN111130425A (zh) * 2019-12-23 2020-05-08 潍柴动力股份有限公司 死区补偿方法、装置、电机驱动器及存储介质
CN111917318A (zh) * 2020-07-08 2020-11-10 南京南瑞继保电气有限公司 一种模块化多电平换流器的桥臂电流方向确定方法

Family Cites Families (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN102130619B (zh) * 2011-03-21 2014-07-02 中国电力科学研究院 一种模块化多电平变流器的均压控制方法
CN103941073B (zh) * 2014-04-30 2017-03-29 国家电网公司 一种判断级联换流器桥臂电流方向的装置

Patent Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPH0698557A (ja) * 1992-09-14 1994-04-08 Fuji Electric Co Ltd パルス幅変調制御インバータの制御回路
JP2005184905A (ja) * 2003-12-17 2005-07-07 Mitsubishi Electric Corp インバータ装置
CN101820231A (zh) * 2010-04-15 2010-09-01 浙江大学 用于变频器的电流过零检测及死区补偿方法
CN103901257A (zh) * 2014-03-04 2014-07-02 国家电网公司 模块化多电平换流器桥臂电流方向测量装置及判断方法
CN111130425A (zh) * 2019-12-23 2020-05-08 潍柴动力股份有限公司 死区补偿方法、装置、电机驱动器及存储介质
CN111917318A (zh) * 2020-07-08 2020-11-10 南京南瑞继保电气有限公司 一种模块化多电平换流器的桥臂电流方向确定方法

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