KR102576611B1 - Voltage control device - Google Patents

Abstract

The present invention relates to a voltage control device that generates individual voltage commands to control the voltage for each module of a voltage-type converter in which a plurality of modules are connected in series, comprising: a control unit that generates an average voltage command; An individual power deviation is calculated using a module average voltage for the plurality of modules and an individual module voltage measured from each of the plurality of modules, and the individual power deviation is compared with a power range for each of the plurality of modules, an individual voltage command generator that generates an individual voltage command for each of the plurality of modules using the individual power deviation and the average voltage command; and a reactive current command generator that processes a power deviation error and generates a reactive current command.

Description

Voltage control device {VOLTAGE CONTROL DEVICE}

The present invention relates to a voltage control device, and more specifically, to a voltage control device that generates individual voltage commands to control the voltage for each module of a voltage-type converter in which a plurality of modules are connected in series.

Converters that convert AC power to DC power or DC power to AC power by connecting directly to the medium, high voltage system, such as STATCOM (Static Synchronous Compensator) to improve voltage quality or bidirectional converters for motor driving, are widely used. It is used.

This converter is provided with a plurality of arms. Additionally, each arm is provided with a switch. However, there is a limit to the voltage that the switch can withstand high pressure.

The number of modules provided in each arm is determined by the processing capacity of the converter, and may be provided as many as hundreds.

The voltage value of the capacitor of each of the plurality of modules provided in this way is not fixed but varies depending on the driving situation. In addition, when these modules are manufactured by different manufacturers, the capacitor specifications of each module are different, so the capacitor capacity of each module is different, which may ultimately result in the voltage of the capacitor of each module being different.

To this end, the modular multi-level converter performs balancing control to maintain equal voltage between modules in each arm.

When the voltage between modules is unbalanced, power may be input to each module to resolve the imbalance. At this time, the input power is proportional to the current flowing in the load of each module. In other words, the power applied to each module to correct voltage imbalance is affected by the current flowing in the load of each module.

However, in the existing converter's voltage control method, the current command is adjusted to keep the overall DC link voltage constant independently of the voltage balance control. In particular, the phase of the current command is determined to match the phase of the voltage source. At this time, the current command is determined by the size of the load connected to each DC terminal. Therefore, when the size of the load is small or there is no load, the current command also becomes small or 0, and the amount of power to resolve the voltage imbalance also becomes small, which reduces the voltage control ability of the voltage control device.

The voltage control device according to an embodiment of the present invention generates individual voltage commands to control the voltage for each module of a voltage-type converter, thereby resolving voltage imbalance between multiple modules to improve the performance of the converter and increase its lifespan. It has a purpose.

Another purpose of the voltage control device according to an embodiment of the present invention is to enable voltage control in response to loads of various sizes by adding a reactive component to the current command even when the load size of each module of the converter is small or no load. There is.

A voltage control device according to an embodiment of the present invention for solving the above problems is connected to an AC power source and generates an individual voltage command to control the voltage for each module of a voltage-type converter in which a plurality of modules are connected in series. An apparatus comprising: a control unit generating an average voltage command in response to an input of a total voltage command, which is a command value of the total voltage of the plurality of modules; An individual power deviation is calculated using a module average voltage for the plurality of modules and an individual module voltage measured from each of the plurality of modules, and the individual power deviation is compared with a power range for each of the plurality of modules, an individual voltage command generator that generates an individual voltage command for each of the plurality of modules using the individual power deviation and the average voltage command; and a reactive current command generator that generates a reactive current command by processing a power deviation error that occurs in the process of comparing the individual power deviation and the power range of the individual voltage command generator. It includes, and the reactive current command can be input to the control unit and used to generate the average voltage command.

The control unit may generate an active current command in response to an input of the total module voltage and the total voltage command, which is the sum of the voltages applied to the plurality of modules, and generate an average voltage command in response to the active current command.

The active current command may have the same phase as the AC power, and the reactive current command may have a phase difference of 90 degrees or -90 degrees from the active current command.

The control unit includes a first voltage control unit that generates a total power command in response to a difference between the module total voltage and the total voltage command; a first conversion unit that converts the total power command into the active current command; and a current control unit that generates the average voltage command in response to the sum of the active current command and the reactive current command. may include.

The reactive current command generator receives the power deviation error from each of the plurality of modules and controls the generation amount of the reactive current command so that the power deviation of each of the plurality of modules is within the power range of each of the plurality of modules. You can.

The individual voltage command generator may include a second voltage control unit that calculates the individual power deviation in response to the module average voltage divided by the number of modules and the individual module voltage. and comparing the individual power deviation with the power range of the module, passing the individual power deviation within the power range of the module in the range of the individual power deviation, and passing the individual power deviation within the power range of the module in response to the individual power deviation outside the power range of the module. A comparison unit that generates an error; It may further include.

The power deviation error may include information about the extent to which the individual power deviation deviates from the maximum or minimum power range of the module's power range.

The individual voltage command generator may include a second converter that converts the individual power deviation into an individual voltage fluctuation value; It may further include, and generate the individual voltage command for each of the modules to follow from the difference between the individual voltage fluctuation value and the average voltage command generated by the control unit.

A voltage control device according to another embodiment of the present invention for solving the above problems is connected to an AC power source and generates an individual voltage command to control the voltage for each module of a voltage converter in which a plurality of modules are connected in series. An apparatus comprising: a first control unit generating an individual power command in response to an individual module voltage measured from each of the plurality of modules; a second control unit generating an average voltage command in response to a total power command that is the sum of the individual power commands; Calculate an individual power deviation using an average of individual power commands for each of the plurality of modules and the individual power command input from the first control unit, and compare the individual power deviation with a power range for each of the plurality of modules. , an individual voltage command generator that generates an individual voltage command for each of the plurality of modules using the individual power deviation and the average voltage command; and a reactive current command generator that generates a reactive current command by processing a power deviation error that occurs in the process of comparing the individual power deviation and the power range of the individual voltage command generator. It includes, and the reactive current command can be input to the first control unit and used to generate the average voltage command.

The first control unit includes a first voltage control unit configured to generate the individual power command in response to a DC link voltage command for each of the plurality of modules and an input of the module individual voltage; may include.

The second control unit includes a first conversion unit that converts a total power command summing up all the individual power commands of the plurality of modules into an active current command; and a current control unit that generates the average voltage command in response to the sum of the active current command and the reactive current command. may include.

The active current command may have the same phase as the AC power, and the reactive current command may have a phase difference of 90 degrees or -90 degrees from the active current command.

The reactive current command generator receives the power deviation error from each of the plurality of modules and sets the reactive current command so that the power deviation of each of the plurality of modules is within the power range of each of the plurality of modules. The amount of production can be controlled.

The individual voltage command generator compares the individual power deviation with the power range of the module, passes the individual power deviation within the power range of the module in the range of the individual power deviation, and passes the individual power deviation within the power range of the module to the individual power deviation outside the power range of the module. a comparison unit correspondingly generating the power deviation error; It may further include.

The power deviation error may include information about the extent to which the individual power deviation deviates from the maximum or minimum power range of the module's power range.

The individual voltage command generator may include a second converter that converts the individual power deviation into an individual voltage fluctuation value; It may further include, and generate the individual voltage command for each of the modules to follow from the difference between the individual voltage fluctuation value and the average voltage command generated by the second control unit.

The voltage control device according to an embodiment of the present invention generates individual voltage commands to control the voltage for each module of a voltage-type converter, thereby resolving voltage imbalance between multiple modules, improving the performance of the converter and increasing its lifespan. There is.

The voltage control device according to an embodiment of the present invention enables voltage control in response to loads of various sizes by adding a reactive component to the current command even when the load size of each module of the converter is small or no load.

The accompanying drawings, which are included as part of the detailed description to aid understanding of the present invention, provide embodiments of the present invention, and together with the detailed description, explain the technical idea of the present invention.
Figure 1 is a diagram illustrating a voltage control device and a voltage-type converter controlled through the voltage control device according to an embodiment of the present invention.
FIG. 2 is a diagram for explaining the control unit of the voltage control device of FIG. 1 in more detail.
FIG. 3 is a diagram for explaining in more detail the individual voltage command generator of the voltage control device of FIG. 1.
FIG. 4 is a diagram for explaining the reactive current command generator of FIG. 1 in more detail.
Figure 5 is a diagram illustrating a voltage control device and a voltage-type converter controlled through the voltage control device according to another embodiment of the present invention.
FIG. 6 is a diagram for explaining the first control unit of FIG. 5 in more detail.
FIG. 7 is a diagram for explaining the second control unit of FIG. 5 in more detail.
FIG. 8 is a diagram for explaining the individual voltage command generator of FIG. 5 in more detail.
Figure 9 is a diagram illustrating a voltage control device and a voltage-type converter controlled through the voltage control device according to another embodiment of the present invention.

The present invention can be modified in various ways and can have various embodiments. Hereinafter, specific embodiments will be described in detail based on the accompanying drawings.

The following examples are provided to provide a comprehensive understanding of the methods, devices and/or systems described herein. However, this is only an example and the present invention is not limited thereto.

In describing the embodiments of the present invention, if it is determined that a detailed description of the known technology related to the present invention may unnecessarily obscure the gist of the present invention, the detailed description will be omitted. In addition, the terms described below are terms defined in consideration of functions in the present invention, and may vary depending on the intention or custom of the user or operator. Therefore, the definition should be made based on the contents throughout this specification. The terminology used in the detailed description is only for describing embodiments of the present invention and should in no way be limiting. Unless explicitly stated otherwise, singular forms include plural meanings. In this description, expressions such as “comprising” or “comprising” are intended to indicate certain features, numbers, steps, operations, elements, parts or combinations thereof, and one or more than those described. It should not be construed to exclude the existence or possibility of any other characteristic, number, step, operation, element, or part or combination thereof.

In addition, terms such as first, second, etc. may be used to describe various components, but the components are not limited by the terms, and the terms are used for the purpose of distinguishing one component from another component. It is used only as

Hereinafter, embodiments illustrating the present invention will be described in detail with reference to the attached drawings.

Figure 1 is a diagram illustrating a voltage control device 30 and a voltage-type converter controlled through the voltage control device according to an embodiment of the present invention.

Referring to FIG. 1, a voltage-type converter may include an AC power source 10, a plurality of modules 20, and a load 21 connected to each of the plurality of modules 20.

The converter in Figure 1 shows the circuit structure of a CHB (Cascaded H-Bridge) type converter. This converter has several modules 20 connected in series to correspond to the voltage level of the input AC power, and an independent DC load 21 or power source can be connected to the DC terminal of each module.

The number of modules 20 connected in series may vary depending on the magnitude of the alternating current voltage. The module 20 in FIG. 1 illustrates that it has the structure of a 2-level H-bridge inverter/converter. However, the present invention is not limited to this and can be implemented even when the module 20 is composed of a 3-level NPC (Neutral Point Clamped) converter structure or various other voltage source converters.

In addition, Figure 1 illustrates a structure in which a CHB-type converter is connected to a single-phase AC power source 10, but in addition, the CHB-type converter may be connected to a three-phase AC power source. A more detailed description of this will be provided later.

When the load 21 or power source of each module 20 consumes or supplies the same amount of power, the DC terminal voltage of each module 20 remains the same, but if a difference occurs between these powers, each module ( A difference may occur between the DC terminal voltages in 20). In order to control the DC terminal voltage of these modules 20 equally, balancing control is required. This balance control may be performed by the voltage control device 30.

The voltage control device 30 is connected to each module 20 of the converter and can maintain the DC terminal voltage of each module 20 at a constant value. In the embodiment of FIG. 1, the voltage control device 30 may include a control unit 100, an individual voltage command generator 200, and a reactive current command generator 300.

The control unit 100 may generate an average voltage command in response to the input of the total voltage command, which is the command value of the total voltage of the plurality of modules 20.

The individual voltage command generator 200 calculates an individual power deviation using the module average voltage for a plurality of modules and the module individual voltage measured from each of the plurality of modules, and calculates the individual power deviation and each of the plurality of modules. The power ranges for each module may be compared, and individual voltage commands for each of the plurality of modules may be generated using the individual power deviation and the average voltage command.

The reactive current generator 300 may generate a reactive current command by processing a power deviation error that occurs in the process of comparing the individual power deviation of the individual voltage command generator and the power range.

The control unit 100 is connected to all modules 20 of the converter and can receive the total module voltage, which is the sum of the DC terminal voltages of each module 20. The individual voltage command generator 200 is connected to each module 20 of the converter and can receive the individual module voltage measured from each module 20. To this end, the number of individual voltage command generators 200 may be configured to correspond to the number of each module 20 of the converter.

More detailed information about each configuration of the voltage control device 30 will be described with reference to FIGS. 2 to 4.

FIG. 2 is a diagram for explaining the control unit 100 of the voltage control device 30 of FIG. 1 in more detail.

Referring to FIG. 2 , the control unit 100 may include a first voltage control unit 110, a first conversion unit 120, and a current control unit 130.

The control unit 100 generates an active current command (id.ref) in response to the input of the total module voltage (Vdc.tot) and the total voltage command (Vdc.ref.tot), which combine the voltages applied to the plurality of modules 20. and generate an average voltage command (Vdc.ref.avg) in response to the active current command (id.ref).

Here, the total module voltage (Vdc.tot) may mean the sum of voltages applied to the DC terminal of each module 20. The voltage applied to the DC terminal of the module 20 can be measured through the voltage difference between both ends of the capacitor configured in the DC terminal. The overall voltage command (Vdc.ref.tot) is a voltage value that the module overall voltage (Vdc.tot) must follow, and can be arbitrarily set depending on the designer of the voltage control device 30 or the voltage control environment.

The control unit 100 calculates the difference between the total module voltage (Vdc.tot) and the total voltage command (Vdc.ref.tot), and the calculated value can be input to the first voltage control unit 110 of the control unit 100. there is.

The first voltage control unit 110 may generate a total power command (Pref.tot) from the difference between the input total module voltage (Vdc.tot) and the total voltage command (Vdc.ref.tot). Here, the first voltage control unit 110 may be understood as a type of DC-link voltage regulator. The interior of the first voltage control unit 110 may be implemented in various forms to generate power in response to the input voltage. The size of the total power command (Pref.tot) may be generated in response to the size of the difference between the module total voltage (Vdc.tot) and the total voltage command (Vdc.ref.tot).

Thereafter, the first conversion unit 120 may convert the total power command (Pref.tot) into an active current command (id.ref). The active current command (id.ref) is converted to correspond to the size of the total power command (Pref.tot).

That is, the first voltage control unit 110 and the first conversion unit 120 are used to generate a current command corresponding to the difference between the input module total voltage (Vdc.tot) and the total voltage command (Vdc.ref.tot). It can be understood as a composition. In another embodiment of the present invention, the first conversion unit 120 may be included within the first voltage control unit 110 and perform its function.

At this time, the active current command (id.ref) output from the first converter 120 includes an active current component having the same phase as the AC power supply 10 of FIG. 1.

As described above, the control unit 100 may generate an active current command by adding a reactive current command (iq.ref) to the active current command (id.ref) having the same phase as the AC power supply 10. The reactive current command (iq.ref) includes a reactive current component that differs from the AC power source 10 by 90 degrees or -90 degrees. Accordingly, the active current command (id.ref) and the reactive current command (iq.ref) are combined to expand the power range of the module 20, which will be described later.

The current control unit 130 provides an average voltage command (Vac) so that the current (i) measured in the plurality of modules 20 can follow the sum of the active current command (id.ref) and the reactive current command (iq.ref). .ref.avg) can be created.

The average voltage command (Vac.ref.avg) may mean the total voltage command (Vdc.ref.tot) required for current control divided by the number of modules. The measured current (i) may mean the amount of current that actually flows between modules 20 connected in series.

FIG. 3 is a diagram for explaining the individual voltage command generator 200 of the voltage control device 30 of FIG. 1 in more detail. Referring to FIG. 3 , the individual voltage command generator 200 may include a second voltage control unit 210, a comparison unit 220, and a second conversion unit 230.

The second voltage control unit 210 divides the overall module voltage (Vdc.tot) by the number of modules 20, and divides the module average voltage (Vdc.avg) and the module individual voltage (Vdc.i) into individual power deviations (△). Pref.i) can be calculated. That is, the second voltage control unit 210 determines the voltage measured from the module 20 connected to the individual voltage command generator 200 from the difference between the module average voltage (Vdc.avg) and the module individual voltage (Vdc.i). You can see how much it differs from the overall average voltage. Through this, the second voltage control unit 210 can derive the power deviation (△Pref.i) required at the DC terminal of each module 20.

However, in order to resolve the voltage imbalance situation between modules, the power range (△P.i) that can be input to each module is determined by the individual voltage fluctuation value (△Vac.ref.i) and the current flowing in the module ( It can be expressed as the product of i).

[Formula 1]

△P.i = △Vac.ref.i * i

In order to resolve voltage imbalance, the power range (△P.i) that can be applied to each module is not only the individual voltage fluctuation value (△Vac.ref.i) of each module, but also the current flowing in the load 21 of the corresponding module 20. It is also affected by the size of . Accordingly, when the size of the load 21 is small or 0, the size of the current flowing through the corresponding load 21 also becomes small, so that sufficient power to resolve the voltage imbalance may not be provided to the module. In other words, if the power range (P.i) available for a module is small compared to the size of the power deviation (△Pref.i) required for voltage balancing of any module, there is a problem in which the voltage balancing ability is deteriorated.

The comparison unit 220 compares the individual power deviation (△Pref.i) with the power range of the module 20 and outputs within the power range of the module 20 in the range of the individual power deviation (△Pref.i). An individual power deviation (ΔPsat.i) may be passed, and a power deviation error (ΔPerr.i) may be generated in response to an individual power deviation outside the power range of the module 20.

In more detail, the comparison unit 220 determines the maximum individual voltage fluctuation value (△Vac.ref.i) that can be generated by each module and the power deviation (△Pref.i) that can be generated by each module by current. The maximum value (positive value, △Pref.max.i) and minimum value (negative value, △Pref.min.i) can be obtained. The comparison unit 220 may compare the range of power deviation that can be output (△Pref.min.i<△P.i<△Pref.max.i) obtained in this way with the required power deviation (△Pref.i). The comparator 220 can only pass the outputable power deviation (△Psat.i) among the required power deviations (△Pref.i).

The comparator 220 may generate a power deviation error (△Perr.i) when the output power range is smaller than the required power deviation (△Pref.i). Here, the power deviation error (△Perr.i) is the individual power deviation (△Pref.i) from the maximum power range (△Pref.max.i) or minimum power range (△Pref.min.i) of the module's power range. Information about the degree of deviation may be included.

The second conversion unit 230 may convert the outputable individual power deviation (△Psat.i) that has passed through the comparison unit 220 into an individual voltage variation value (△Vac.ref.i). Accordingly, the individual voltage command generator 200 determines the module 20 from the difference between the individual voltage fluctuation value (△Vac.ref.i) and the average voltage command (Vac.ref.avg) generated by the control unit 100. Each can generate an individual voltage reference (Vac.ref.i) to follow.

FIG. 4 is a diagram for explaining the reactive current command generator 300 of FIG. 1 in more detail.

The reactive current command generator 300 processes the power deviation error (△Perr.i) that occurs in the process of comparing the individual power deviation (△Pref.i) and the power range of the individual voltage command generator (200) and An active current reference (iq.ref) can be generated.

When referring to [Equation 1] above, the size of the load 21 is not something that can be controlled through the voltage control device 30. In addition, when controlling the size of the active current command (id.ref) of the active component current that is in phase with the AC power source to change the size of the current i, the voltage at the DC terminal of each module decreases or increases overall, resulting in an average module average. There is a problem in which the voltage (Vdc.avg) changes.

The reactive current command generator 300 is 90 degrees from the phase of the AC power in response to the power deviation error (△Perr.i) of each module provided from the individual voltage command generator 200 configured to correspond to each module. Alternatively, by providing the reactive component current with a phase difference of -90 degrees to the active current command (id.ref), the power range of each module can be expanded without changing the module average voltage (Vdc.avg).

In addition, the reactive current command generator 300 receives the power deviation error (△Perr.i) from the individual voltage command generator 200 configured for each of the plurality of modules and generates the active current command (id.ref). ) can be controlled to control the generation amount of the reactive current command (iq.ref) so that it falls within the power range of each of the plurality of modules.

As expressed in [Equation 1], the input power range of each module is determined by the individual voltage fluctuation value (△Vac.ref.i) of each module and the current (i) flowing through the module. Accordingly, the reactive current command generator 300 can adjust the reactive current command (iq.ref) so that the current (i) that satisfies the individual power deviation (△Pref.i) flows in this input power range.

Figure 5 is a diagram illustrating a voltage control device and a voltage-type converter controlled through the voltage control device according to another embodiment of the present invention. Hereinafter, in describing FIGS. 5 to 8, descriptions of configurations or effects that overlap with the embodiment previously described in FIGS. 1 to 4 will be omitted.

The structure of the voltage control device 31 of FIGS. 5 to 8 is different from the previous voltage control device 30, and the voltage control device 31 may be configured to control voltage for each module.

Unlike the control unit 100 of FIG. 1, the first control unit 101 and the second control unit 102 of the voltage control device 30 of FIG. 5 include a first control unit 101 connected to each module 20 and It consists of an overall module 20 and a second control unit 102 connected to the first control unit 101. The individual voltage command generator 201 may be configured to correspond to each module 20.

The first control unit 101 may generate an individual power command in response to the individual module voltage measured from each of the plurality of modules 20.

The second control unit 102 may generate an average voltage command in response to the total power command that is the sum of the individual power commands.

The individual voltage command generator 201 calculates an individual power deviation using the average individual power command for each of the plurality of modules 20 and the individual power command input from the first control unit, and calculates the individual power deviation and the The power range for each of the plurality of modules may be compared, and an individual voltage command for each of the plurality of modules may be generated using the individual power deviation and the average voltage command.

The reactive current generator 300 may generate a reactive current command by processing a power deviation error that occurs in the process of comparing the individual power deviation and the power range of the individual voltage command generator.

FIG. 6 is a diagram for explaining the first control unit 101 of FIG. 5 in more detail. Referring to FIG. 6, the first control unit 101 may include a first voltage control unit 111.

The first voltage control unit 111 provides the individual power command in response to the input of the DC link voltage command (Vdc.ref) for each of the plurality of modules 20 and the module individual voltage (Vdc.i) measured from each module. (Pref.i) can be created.

Here, the first voltage control unit 110 may be understood as a type of DC-link voltage regulator. The interior of the first voltage control unit 110 may be implemented in various forms to generate power in response to the input voltage. The size of the individual power command (Pref.i) may be generated in response to the size of the difference between the DC link voltage command (Vdc.ref) and the module individual voltage (Vdc.i).

Here, the DC link voltage command (Vdc.ref) is a voltage value that the DC link voltage of each module must follow, and can be arbitrarily set depending on the designer of the voltage control device 31 or the voltage control environment. The individual power command (Pref.i) may refer to the power command required for the DC voltage of each module to follow the DC voltage command.

FIG. 7 is a diagram for explaining the second control unit 102 of FIG. 5 in more detail. The second control unit 102 may include a first conversion unit 121 and a current control unit 131.

The first conversion unit 121 may convert the total power command (Pref.tot), which is the sum of all individual power commands (Pref.i) of the plurality of modules 20, into an active current command (id.ref).

That is, the first voltage control unit 111 and the first conversion unit 121 are configured to generate a current command corresponding to the difference between the input DC link voltage command (Vdc.ref) and the module individual voltage (Vdc.i). It can be understood as In another embodiment of the present invention, the first conversion unit 121 may be included within the first voltage control unit 111 and perform its function. At this time, the individual power command (Pref.i) output from the first converter 120 includes an active current component having the same phase as the AC power source 10 of FIG. 5.

As described above, the second control unit 102 may generate a total current command by adding a reactive current command (iq.ref) to the total current command (id.ref) having the same phase as the AC power supply 10. The reactive current command (iq.ref) includes a reactive current component that differs from the AC power source 10 by 90 degrees or -90 degrees. Accordingly, the total current command (id.ref) and the reactive current command (iq.ref) are combined to expand the available power range for voltage control of the module 20, which will be described later.

The current control unit 131 may generate the average voltage command (Vac.ref.avg) in response to the sum of the active current command (id.ref) and the reactive current command (iq.ref).

In more detail, the current control unit 131 allows the current (i) measured in the plurality of modules 20 to follow the sum of the active current command (id.ref) and the reactive current command (iq.ref). The average voltage command (Vac.ref.avg) can be generated.

The average voltage command (Vac.ref.avg) may mean the total voltage command (Vdc.ref.tot) required for current control divided by the number of modules. The measured current (i) may mean the amount of current that actually flows between modules 20 connected in series.

FIG. 8 is a diagram for explaining the individual voltage command generator 201 of FIG. 5 in more detail. Referring to FIG. 8 , the individual voltage command generator 201 may include a comparison unit 211 and a second conversion unit 221.

The individual voltage command generator 201 may calculate the individual power deviation (△Pref.i) in response to the individual power command average (Pref.avg) and the individual power command (Pref.i). That is, the individual voltage command generator 201 determines the individual voltage of the module 20 connected to the individual voltage command generator 201 from the difference between the individual power command average (Pref.avg) and the individual power command (Pref.i). You can see how much it differs from the overall average of the module. Through this, the power deviation (△Pref.i) required at the DC terminal of each module 20 can be derived.

The comparison unit 211 compares the individual power deviation (△Pref.i) with the power range of the module 20 and outputs within the power range of the module 20 in the range of the individual power deviation (△Pref.i). An individual power deviation (ΔPsat.i) may be passed, and a power deviation error (ΔPerr.i) may be generated in response to an individual power deviation outside the power range of the module 20.

In more detail, the comparison unit 211 determines the maximum individual voltage fluctuation value (△Vac.ref.i) that can be generated by each module and the power deviation (△Pref.i) that can be generated by each module by current. The maximum value (positive value, △Pref.max.i) and minimum value (negative value, △Pref.min.i) can be obtained. The comparison unit 211 may compare the range of power deviation that can be output (△Pref.min.i<△P.i<△Pref.max.i) obtained in this way with the required power deviation (△Pref.i). The comparator 211 can only pass the outputable power deviation (△Psat.i) among the required power deviations (△Pref.i).

The comparator 211 may generate a power deviation error (△Perr.i) when the output power range is smaller than the required power deviation (△Pref.i). Here, the power deviation error (△Perr.i) is the individual power deviation (△Pref.i) from the maximum power range (△Pref.max.i) or minimum power range (△Pref.min.i) of the module's power range. Information about the degree of deviation may be included.

The second conversion unit 221 may convert the outputable individual power deviation (△Psat.i) that has passed through the comparison unit 211 into an individual voltage variation value (△Vac.ref.i). Accordingly, the individual voltage command generator 201 generates a module ( 20) Individual voltage commands (Vac.ref.i) can be generated for each to follow.

Figure 9 is a diagram illustrating a voltage control device and a voltage-type converter controlled through the voltage control device according to another embodiment of the present invention.

Referring to FIG. 9, it can be seen that the module 20 and load 21 connected to the voltage control device 30 do not have a single-phase multi-level CHB converter structure, unlike FIG. 1, but are three-phase multi-level CHB converters. The voltage control device according to an embodiment of the present invention is connected to each module of a three-phase multi-level converter and can perform voltage control between modules.

The above description is merely an illustrative explanation of the technical idea of the present invention, and various modifications and variations will be possible to those skilled in the art without departing from the essential characteristics of the present invention. Accordingly, the embodiments described in the present invention are for illustrative purposes rather than limiting the technical idea of the present invention, and are not limited to these embodiments. The scope of protection of the present invention shall be interpreted in accordance with the claims below, and all technical ideas within the scope equivalent thereto shall be construed as being included in the scope of rights of the present invention.

10: AC power 20: Module
21: load 30: voltage control device
100: Control unit 200: Individual voltage command generation unit
300: Reactive current command generator

Claims (16)

In the voltage control device that is connected to an alternating current power source and generates an individual voltage command to control the voltage for each module of a voltage-type converter in which a plurality of modules are connected in series,
a control unit that generates an average voltage command in response to an input of a total voltage command, which is a command value of the total voltage of the plurality of modules;
An individual power deviation is calculated using a module average voltage for the plurality of modules and an individual module voltage measured from each of the plurality of modules, and the individual power deviation is compared with a power range for each of the plurality of modules, an individual voltage command generator that generates an individual voltage command for each of the plurality of modules using the individual power deviation and the average voltage command; and
a reactive current command generator that generates a reactive current command by processing a power deviation error that occurs in the process of comparing the individual power deviation and the power range of the individual voltage command generator; Including,
The control unit generates an active current command in response to the input of the total module voltage and the total voltage command, which is the sum of the voltages applied to the plurality of modules, and generates an average voltage in response to the sum of the active current command and the reactive current command. A voltage control device characterized in that it generates a command. delete According to claim 1,
The active current command has the same phase as the AC power,
A voltage control device, characterized in that the reactive current command has a phase difference of 90 degrees or -90 degrees from the active current command. The method of claim 3, wherein the control unit
a first voltage control unit that generates a total power command in response to a difference between the module total voltage and the total voltage command;
a first conversion unit that converts the total power command into the active current command; and
a current control unit generating the average voltage command in response to the sum of the active current command and the reactive current command; A voltage control device comprising: The method of claim 1, wherein the reactive current command generator
A voltage control device that receives the power deviation error from each of the plurality of modules and controls the generation amount of the reactive current command so that the power deviation of each of the plurality of modules is within the power range of each of the plurality of modules. . The method of claim 1, wherein the individual voltage command generator
a second voltage control unit that calculates the individual power deviation in response to the module average voltage divided by the number of modules and the module individual voltage; and
Compare the individual power deviation with the power range of the module, pass the individual power deviation within the power range of the module in the range of the individual power deviation, and generate the power deviation error in response to the individual power deviation outside the power range of the module. A comparison unit that generates; A voltage control device further comprising: The method of claim 6, wherein the power deviation error is
Voltage control device, characterized in that it includes information about the degree to which the individual power deviation deviates from the maximum power range or the minimum power range of the power range of the module. The method of claim 6, wherein the individual voltage command generator
a second converter converting the individual power deviation into an individual voltage fluctuation value; It further includes,
A voltage control device characterized in that the individual voltage command is generated for each of the modules to follow from the difference between the individual voltage fluctuation value and the average voltage command generated by the control unit. In the voltage control device that is connected to an alternating current power source and generates an individual voltage command to control the voltage for each module of a voltage-type converter in which a plurality of modules are connected in series,
a first control unit generating individual power commands in response to individual module voltages measured from each of the plurality of modules;
a second control unit generating an average voltage command in response to a total power command that is the sum of the individual power commands;
Calculate an individual power deviation using an average of individual power commands for each of the plurality of modules and the individual power command input from the first control unit, and compare the individual power deviation with a power range for each of the plurality of modules. , an individual voltage command generator that generates an individual voltage command for each of the plurality of modules using the individual power deviation and the average voltage command; and
a reactive current command generator that generates a reactive current command by processing a power deviation error that occurs in the process of comparing the individual power deviation and the power range of the individual voltage command generator; Including,
The second control unit converts the total power command, which is the sum of all the individual power commands of the plurality of modules, into an active current command, and generates the average voltage command in response to the sum of the active current command and the reactive current command. A voltage control device characterized in that. The method of claim 9, wherein the first control unit
a first voltage control unit configured to generate the individual power command in response to a DC link voltage command for each of the plurality of modules and an input of the module individual voltage; A voltage control device comprising: delete According to clause 9,
The active current command has the same phase as the AC power,
A voltage control device, characterized in that the reactive current command has a phase difference of 90 degrees or -90 degrees from the active current command. The method of claim 9, wherein the reactive current command generator
Characterized by receiving the power deviation error from each of the plurality of modules and controlling the generation amount of the reactive current command so that the power deviation of each of the plurality of modules is within the power range of each of the plurality of modules. voltage control device. The method of claim 9, wherein the individual voltage command generator
Compare the individual power deviation with the power range of the module, pass the individual power deviation within the power range of the module in the range of the individual power deviation, and generate the power deviation error in response to the individual power deviation outside the power range of the module. A comparison unit that generates; A voltage control device further comprising: The method of claim 14, wherein the power deviation error is
Voltage control device, characterized in that it includes information about the degree to which the individual power deviation deviates from the maximum power range or the minimum power range of the power range of the module. The method of claim 14, wherein the individual voltage command generator
a second converter converting the individual power deviation into an individual voltage fluctuation value; It further includes,
A voltage control device characterized in that the individual voltage command for each of the modules to follow is generated from the difference between the individual voltage fluctuation value and the average voltage command generated by the second control unit.

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