CN109818508B - Voltage control method and device for flexible direct current converter valve submodule - Google Patents
Voltage control method and device for flexible direct current converter valve submodule Download PDFInfo
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Abstract
The invention provides a voltage control method and a device for submodules of a flexible direct current converter valve, which are characterized in that different types of submodules of each bridge arm of the flexible direct current transmission converter valve are grouped, each group corresponds to a valve control device, the upper control device for valve control calculates the number of the submodules which are put into operation according to the weight of each group, and then according to the deviation degree of the grouped voltage of each submodule relative to the rated voltage of the submodule, dynamically adjusting the weight calculated before, finally calculating the number of the sub-modules which are finally put into operation of each group by combining the maximum normal sub-module number which can be put into operation of the corresponding bridge arm, sending the number of the sub-modules into operation to the valve control device, therefore, the problem of sub-module overvoltage or undervoltage caused by too slow change of the number of input sub-modules due to weight influence in the dynamic process of the flexible direct current transmission system is solved, and the valve control device works according to a voltage equalizing strategy and a gating method provided by the existing literature.
Description
Technical Field
The invention belongs to the technical field of power electronics, and particularly relates to a voltage control method and device for a flexible direct current converter valve submodule.
Background
With the development of power electronic technology, flexible direct-current transmission technology based on a modular multilevel converter is widely researched and applied. The bridge arm of the topology adopts a basic operation unit cascade mode, so that the problems of direct series connection of a large number of switching devices, no driving consistency and the like are solved, and the technical barrier of direct current transmission is greatly reduced. And voltage-sharing control is needed for a large number of sub-module units connected in series.
At present, a submodule voltage-sharing strategy generally adopts a submodule capacitor voltage sequencing method, but when the number of bridge arm submodules is too large, the time overhead proportion of a sequencing algorithm is too large, the load rate of a valve control device is too high, the number of submodules is correspondingly increased along with the increase of voltage grades, and the time overhead of the sequencing algorithm is increased in a geometric grade. On the other hand, each sub-module needs to communicate with the valve control device, the communication interface between the valve control device and the sub-module is increased along with the increase of the number of links, and the expansion of hardware can cause the substantial increase of cost and the increase of development period, which is not favorable for the expansion of the valve control device.
Meanwhile, in order to solve the problem of restarting after a direct current line fault, submodules of various topological types are diversified, and the basic half-bridge submodule (HB-MMC) is developed into a full-bridge submodule (FB-MMC), a full-bridge-like submodule (SFB-MMC) and the like. The modular multilevel converter based on the full-bridge submodule has more switching devices, low utilization rate of the switching devices and large operation loss. In order to realize the economy of the flexible direct current transmission technology and the characteristic of direct current fault clearing, patent WO2012103936a1 proposes a hybrid modular multilevel converter (HBFB-MMC) scheme based on half-bridge and full-bridge sub-modules, which has the advantages of both HB-MMC and FB-MMC, and reduces switching devices by about 1/4 compared with the FB-MMC scheme while having direct current fault clearing capability. The current converter scheme with various types of submodules which are mixed like a half bridge and a full bridge and coexist is also a future development direction, but the charge-discharge characteristics of each type of submodule are inconsistent, so that difficulty is brought to voltage sharing of various types of submodules.
Patent CN201210451946 proposes a "submodule grouping voltage-sharing control method for a modular multilevel converter", which averagely groups submodules, calculates total voltage of each group, and calculates energy balance factors of each group, thereby calculating the number of submodules required to be input by each group. The algorithm requires average grouping, and does not consider the condition that the number of normal sub-modules is dynamically changed, such as sub-module fault bypass and the like in the running process.
The patent '201410768743.3' proposes a sub-module distributed control method, and for the defects of the patent 'CN 201210451946', proposes that the number of input sub-modules is calculated according to the dynamic change of the number of normal sub-modules and a weighting method, and the method is only suitable for a single type of sub-module grouping and does not consider the condition that the voltage-sharing and charging characteristics are inconsistent after various types of sub-modules are grouped. When the current changes sharply, the voltage difference between different types of sub-modules is large, and even the sub-modules are tripped due to overvoltage, so that the operation stability of the system is affected.
Therefore, a solution with engineering application feasibility is needed to be found, the load rate of the valve control device is reduced, the expandability of the valve control device is improved, the problem that the voltages of the submodules grouped in different groups are uneven in the dynamic process of the system is solved, and the solution is suitable for mixed configuration of the submodules of different types.
Disclosure of Invention
The invention aims to provide a voltage control method and device for a submodule of a flexible direct-current converter valve, which solve the problem of load rate increase of a valve control device caused by the increase of the number of links of the submodule, solve the problems of cost and development period caused by hardware expansion of the valve control device and solve the problem of submodule voltage sharing when different types of submodules are mixed and configured.
In order to achieve the purpose, the invention adopts the technical scheme that:
a voltage control method for sub-modules of a flexible direct current converter valve divides different types of sub-modules of each bridge arm of the converter valve into M groups, wherein M is a natural number and is not less than 1, and the number of the sub-modules in each group is M
Is a natural number, and is provided with a plurality of groups,
i is a grouping serial number, i is more than or equal to 1 and less than or equal to M, each group corresponds to one valve control device, each valve control device operates independently, the number of the input submodules is issued to the valve control devices by an upper layer controller, and the calculation steps of the number of the input submodules are as follows:
(1) the upper layer controller calculates the total number of submodules to be put into corresponding bridge arms
Wherein v isrefFor real-time reference waves, UCNA single sub-module voltage rating;
(2) the upper layer controller calculates the total number of submodules to be put into the bridge arm according to the step (1)
And weight B of the governed valve control deviceiCalculating the number of sub-modules of each valve control device
Where round is a rounding function;
(3) the upper layer controller calculates the average voltage of the submodules of the governed valve control device
Relative to rated voltage UCNDegree of deviation k ofi，
(4) Judging the maximum deviation k calculated by the upper controllermaxAnd minimum degree of deviation kminWhether the difference is larger than a set value k of the average voltage deviation of the submodules set by the valve control deviceNAccording to valve control meansDeviation degree of average voltage of submodule relative to rated voltage and weight B of valve control deviceiAnd dynamically adjusting the number of the sub-modules required to be put into each valve control device in the bridge arm current direction, calculating the number of the final sub-modules put into operation by combining the maximum normal sub-modules which can be put into operation by the corresponding bridge arm, and sending the number of the final sub-modules to each valve control device.
In the method for controlling the voltage of the sub-modules of the flexible direct current converter valve, the specific method for adjusting the number of the sub-modules in the step (4) is as follows:
(41) if k ismax-kmin＜kNKeeping the number of the sub-modules put into each valve control device calculated in the step (2) unchanged; if k ismax-kmin≥kNThen the maximum deviation kmaxAnd minimum degree of deviation kminThe number of the sub-modules put into the corresponding valve control device needs to be adjusted according to the step (42);
(42) upper layer controller collects bridge arm current IarmAnd judging the direction when kmax-kmin≥kNIf the direction is the charging direction, the number of the added sub-modules of the valve control device corresponding to the maximum deviation degree is reduced to 0, and the number of the added sub-modules is reduced and increased to the number of the added sub-modules of the valve control device corresponding to the minimum deviation degree; if bridge arm current IarmIf the direction is the discharging direction, the number of the added sub-modules of the valve control device corresponding to the minimum deviation degree is reduced to 0, the number of the added sub-modules is reduced, and the number of the added sub-modules is increased to the number of the added sub-modules of the valve control device corresponding to the maximum deviation degree;
(43) if the number of the sub-modules put into the valve control device corresponding to the maximum or minimum deviation degree calculated in the step (42) exceeds the maximum number of the normal sub-modules put into the valve control device, the number of the sub-modules put into the valve control device corresponding to the maximum or minimum deviation degree is the maximum number of the normal sub-modules put into the valve control device, and the rest number of the sub-modules needing to be put into the valve control devices is distributed to other valve control devices according to the weights of other valve control devices except the device;
(44) finally, the submodules, calculated by the upper layer controller, of each valve control device are put intoIn the number, only the grouping which can generate positive voltage can be generated, and the number of the submodules calculated by the upper-layer controller satisfies the relation:
the sub-modules calculated by the upper layer controller satisfy the relational expression
When in use
When the sub-module which needs to be put into the group valve control device generates positive voltage, the sub-module generates positive voltage
When the sub-module required to be put into the block valve control device generates zero voltage, the sub-module is used for generating zero voltage
In time, the sub-modules needing to be put into the grouping valve control device are shown to generate negative voltage, and the number of the sub-modules put into the grouping valve control device satisfies the relational expression
In the voltage control method for the sub-modules of the flexible direct current converter valve, the types of the sub-modules are the same or different, and the types of the sub-modules comprise a half-bridge sub-module, a full-bridge sub-module and a full-bridge-like sub-module.
In the voltage control method for the sub-modules of the flexible direct current converter valve, the sub-modules are divided into one group or multiple groups, but each group of sub-modules only allows the sub-module units of a single type.
In the voltage control method for the sub-modules of the flexible direct current converter valve, the grouping principle is as follows: the number of the normal sub-modules corresponding to each group is equal or unequal, and the number of the normal sub-modules in each group is allowed to dynamically change.
In the method for controlling the voltage of the sub-modules of the flexible direct current converter valve, different types of sub-modules can generate different voltages of positive and negative when put into operation, the sub-modules capable of generating negative pressure are grouped, the number of the sub-modules which are finally calculated by the upper layer controller and are grouped is allowed to be negative, and for the sub-modules incapable of generating negative pressure, if the number of the sub-modules which are calculated by the upper layer controller and are put into the sub-modules is negative, the number of the sub-modules which are put into the sub-modules needs to be adjusted, the number of the negative sub-modules which are put into the sub-modules becomes 0, and the negative number.
In the voltage control method for the flexible direct current converter valve submodule, the normal submodule is a submodule capable of participating in normal switching, and does not include a submodule in a bypass state or a locking state.
In the voltage control method for the sub-module of the flexible direct current converter valve, the upper layer controller controls 1 or more bridge arm units.
In the method for controlling the voltage of the sub-module of the flexible direct current converter valve, the charging direction in the step (42) refers to a bridge arm current direction when the voltage of the sub-module rises, and the discharging direction refers to a bridge arm current direction when the voltage of the sub-module falls.
In the method for controlling the voltage of the submodule of the flexible direct current converter valve, the set value k of the average voltage deviation degree of the submoduleN≤40％。
A voltage control device for a submodule of a flexible direct current converter valve comprises a submodule grouping unit, a submodule number input calculating unit, a weight calculating unit, a deviation calculating unit, a submodule number input adjusting unit, a bridge arm current direction judging unit and a submodule input number issuing unit, wherein the submodule grouping unit is used for grouping a plurality of submodules,
the submodule grouping unit divides different types of submodules of each bridge arm of the converter valve into M groups, wherein M is a natural number and is more than or equal to 1, and the number of the submodules in each group is
Is a natural number, and is provided with a plurality of groups,
i is a grouping serial number, i is more than or equal to 1 and less than or equal to M, each group corresponds to one valve control device, each valve control device operates independently, and the number of the input submodules is sent to the valve control devices by an upper layer controller;
the sub-module number input unit is used for calculating the total number of the sub-modules to be input by the corresponding bridge arm
Wherein v isrefFor real-time reference waves, UCNA single sub-module voltage rating;
the weight calculation unit calculates the weight B of the governed valve control device according to the existing weight calculation methodiAnd the total number of the submodules which should be put into the bridge arm and is calculated by the submodule number input calculation unit
Calculating the number of sub-modules of each valve control device
Where round is a rounding function;
the deviation degree calculation unit is used for calculating the average voltage of the sub-modules of the governed valve control device
Relative to rated voltage UCNDegree of deviation k ofi，
And calculating the maximum deviation kmaxAnd minimum degree of deviation kminWhether the difference is larger than a set value k of the average voltage deviation of the submodules set by the valve control deviceN；
The bridge arm current direction judging unit is used for judging the direction of the collected bridge arm current;
the sub-module number input adjusting unit adjusts the number of sub-modules which need to be input into each valve control device and are calculated by the weight calculating unit according to the total sub-module input number calculated by the sub-module number input calculating unit, the weight of each valve control device and the deviation degree calculated by the deviation degree calculating unit, in combination with the bridge arm current direction calculated by the bridge arm current direction judging unit, generates the final sub-module input number in combination with the maximum normal sub-module number which can be input into operation of a corresponding bridge arm, and sends the final sub-module input number to each valve control device by the sub-module input number issuing unit.
And the submodule investment number issuing unit receives the final submodule investment number generated by the submodule number investment adjusting unit and issues the final submodule investment number to each valve control device.
In the foregoing flexible dc converter valve submodule voltage control apparatus, a specific method for adjusting the number of the submodules by the submodule number input adjusting unit is as follows:
(41) if k ismax-kmin＜kNKeeping the number of the submodules which are input by each valve control device and calculated by the number pre-input calculating unit unchanged; if k ismax-kmin≥kNThen the maximum deviation kmaxAnd minimum degree of deviation kminThe number of the sub-modules put into the corresponding valve control device needs to be adjusted according to the step (42);
(42) upper layer controller collects bridge arm current IarmAnd judging the direction when kmax-kmin≥kNIf the direction is the charging direction, the number of the added sub-modules of the valve control device corresponding to the maximum deviation degree is reduced to 0, and the number of the added sub-modules is reduced and increased to the number of the added sub-modules of the valve control device corresponding to the minimum deviation degree; if bridge arm current IarmIf the direction is the discharging direction, the number of the added sub-modules of the valve control device corresponding to the minimum deviation degree is reduced to 0, the number of the added sub-modules is reduced, and the number of the added sub-modules is increased to the number of the added sub-modules of the valve control device corresponding to the maximum deviation degree;
(43) if the number of the sub-modules put into the valve control device corresponding to the maximum or minimum deviation degree calculated in the step (42) exceeds the maximum number of the normal sub-modules put into the valve control device, the number of the sub-modules put into the valve control device corresponding to the maximum or minimum deviation degree is the maximum number of the normal sub-modules put into the valve control device, and the rest number of the sub-modules needing to be put into the valve control devices is distributed to other valve control devices according to the weights of other valve control devices except the device;
(44) and finally, the number of the sub-modules of each valve control device, which is calculated by the upper controller, is only capable of generating positive voltage groups, and the number of the sub-modules calculated by the upper controller satisfies the relation:
the sub-modules calculated by the upper layer controller satisfy the relational expression
When in use
When the sub-module which needs to be put into the group valve control device generates positive voltage, the sub-module generates positive voltage
When the sub-module required to be put into the block valve control device generates zero voltage, the sub-module is used for generating zero voltage
In time, the sub-modules needing to be put into the grouping valve control device are shown to generate negative voltage, and the number of the sub-modules put into the grouping valve control device satisfies the relational expression
In the voltage control device for the sub-modules of the flexible direct current converter valve, the types of the sub-modules are the same or different, and the types of the sub-modules comprise a half-bridge sub-module, a full-bridge sub-module and a full-bridge-like sub-module.
In the flexible voltage control device for the direct current converter valve sub-modules, the grouping principle is that one type of sub-modules are individually divided into one group or multiple groups, but each group of sub-modules only allows a single type of sub-module unit to exist.
In the voltage control device for the sub-module of the flexible dc converter valve, the grouping principle is as follows: the number of the normal sub-modules corresponding to each group is equal or unequal, and the number of the normal sub-modules in each group is allowed to dynamically change.
In the flexible direct current converter valve sub-module voltage control device, different types of sub-modules can generate different positive and negative voltages when put into operation, for sub-module groups capable of generating negative pressure, the number of the sub-modules put into the group, which is finally calculated by the upper layer controller, is allowed to be negative, for sub-module groups incapable of generating negative pressure, if the number of the sub-modules put into the group, which is calculated by the upper layer controller, is negative, the number of the sub-modules put into the group needs to be adjusted, the number of the negative sub-modules put into the group becomes 0, and the negative number is distributed by a valve control device capable of generating negative pressure according to weight.
In the voltage control device for the flexible direct current converter valve submodule, the normal submodule is a submodule capable of participating in normal switching, and does not include a submodule in a bypass state or a locking state.
In the voltage control device for the sub-module of the flexible direct current converter valve, the upper controller controls 1 or more bridge arm units.
In the above flexible dc converter valve sub-module voltage control device, the charging direction in the step (42) is a bridge arm current direction when the sub-module voltage rises, and the discharging direction is a bridge arm current direction when the sub-module voltage drops.
In the above flexible dc converter valve submodule voltage control apparatus, the submodule average voltage deviation degree set value kN≤40％。
After the scheme is adopted, the invention has the beneficial effects that:
(1) the load factor of the valve control device is greatly reduced, and the reliability of the valve control device is improved;
(2) hardware expansion of the valve control device is avoided, so that the development period and the development cost are reduced;
(3) improving the submodule voltage-sharing effect of the current converter with mixed configuration of different types of submodules;
(4) the problem of submodule overvoltage or undervoltage caused by too slow change of input number due to weight influence of voltage of grouping submodules in the dynamic process of the flexible direct current transmission system is solved.
Drawings
FIG. 1 is a view of a sub-module distributed control structure, in which VBC is a valve control device and SM is a sub-module;
FIG. 2 is a half bridge sub-module schematic;
FIG. 3 is a schematic diagram of a full bridge submodule;
fig. 4 is a schematic diagram of a full-bridge-like sub-module.
Detailed Description
The technical solution of the present invention will be described in detail below with reference to the accompanying drawings and specific embodiments.
A voltage control method for sub-modules of a flexible direct current converter valve is characterized in that as shown in figure 1, different types of sub-modules of each bridge arm of the converter valve are divided into M groups, M is a natural number, M is larger than or equal to 1, and the number of molecular modules in each group is M
Is a natural number, and is provided with a plurality of groups,
i is a grouping serial number and is not less than 1 and not more than M, each group corresponds to one valve control device, each valve control device operates independently, the number of the input submodules is issued to the valve control devices by an upper layer controller, and the calculation steps of the number of the input submodules are as follows
(1) The upper layer controller calculates the total number of submodules to be put into corresponding bridge arms
Wherein v isrefFor real-time reference waves, UCNA single sub-module voltage rating;
(2) the upper layer controller calculates the total number of submodules to be put into the bridge arm according to the step (1)
And weight B of the governed valve control deviceiAccording to known methods, for example, the weights may be selected
Calculating the number of sub-modules of each valve control device
Where round is a rounding function;
(3) the upper layer controller calculates the average voltage of the submodules of the governed valve control device
Relative to rated voltage UCNDegree of deviation k ofi，
(4) Judging the maximum deviation k calculated by the upper controllermaxAnd minimum degree of deviation kminWhether the difference is larger than a set value k of the average voltage deviation of the submodules set by the valve control deviceNAccording to the deviation degree of the submodule average voltage of the valve control device relative to the rated voltage and the weight B of the valve control deviceiAnd dynamically adjusting the number of the sub-modules required to be put into each valve control device in the bridge arm current direction, calculating the number of the final sub-modules put into operation by combining the maximum normal sub-modules which can be put into operation by the corresponding bridge arm, and sending the number of the final sub-modules to each valve control device.
In the method for controlling the voltage of the sub-modules of the flexible direct current converter valve, the specific method for adjusting the number of the sub-modules in the step (4) is as follows:
(41) if k ismax-kmin＜kNKeeping the number of the sub-modules put into each valve control device calculated in the step (2) unchanged; if k ismax-kmin≥kNThen the maximum deviation kmaxAnd minimum degree of deviation kminThe number of the sub-modules put into the corresponding valve control device needs to be adjusted according to the step (42);
(42) upper layer controller collects bridge arm current IarmAnd judging the direction when kmax-kmin≥kNIf the direction is the charging direction, the number of the submodules put into the valve control device corresponding to the maximum deviation degree is determined by
Decreasing to 0, increasing the number of the inputted sub-modules to the number of the inputted sub-modules of the valve control device corresponding to the minimum deviation degree, wherein the number of the inputted sub-modules of the valve control device corresponding to the minimum deviation degree is determined by
Become into
If bridge arm current IarmThe direction is the discharging direction, and the number of the submodules put into the valve control device corresponding to the minimum deviation degree is determined by
Decreasing to 0, increasing the number of the inputted sub-modules to the number of the inputted sub-modules of the valve control device corresponding to the maximum deviation degree, wherein the number of the inputted sub-modules of the valve control device corresponding to the large deviation degree is determined by
Become into
(43) If the valve control device corresponding to the maximum or minimum deviation degree calculated according to the step (42) is usedAbsolute value of number of submodules
Greater than the maximum number of normal submodules that it can put in
The number of the submodules which are put into the valve control device and correspond to the maximum or minimum deviation degree is the maximum normal number of the submodules which can be put into the valve control device, and the absolute value of the number of the remaining submodules which need to be put into the valve control device is
Positive and negative and
the number of the remaining submodules required to be input is consistent according to the weight of other valve control devices except the device
Distributing to other valve control devices;
(44) and finally, in the calculated number of the sub-modules of each valve control device, only positive voltage grouping can be generated, and the number of the sub-modules meets the relation:
can generate grouping of positive pressure and negative pressure, and the number of the sub-modules should satisfy the relational expression
When in use
When the sub-module which needs to be put into the group valve control device generates positive voltage, the sub-module generates positive voltage
When the sub-module required to be put into the block valve control device generates zero voltage, the sub-module is used for generating zero voltage
In time, the sub-modules needing to be put into the grouping valve control device are shown to generate negative voltage, and the number of the sub-modules put into the grouping valve control device satisfies the relational expression
In the voltage control method for the sub-modules of the flexible direct current converter valve, the types of the sub-modules are the same or different, and the types of the sub-modules include a half-bridge sub-module shown in fig. 2, a full-bridge sub-module shown in fig. 3, and a full-bridge sub-module shown in fig. 4.
In the voltage control method for the sub-modules of the flexible direct current converter valve, the sub-modules are divided into one group or multiple groups, but each group of sub-modules only allows the sub-module units of a single type.
In the voltage control method for the sub-modules of the flexible direct current converter valve, the grouping principle is as follows: the number of the normal sub-modules corresponding to each group is equal or unequal, and the number of the normal sub-modules in each group is allowed to dynamically change.
In the method for controlling the voltage of the sub-modules of the flexible direct current converter valve, different types of sub-modules can generate different voltages of positive and negative when put into operation, the sub-modules which can generate negative pressure are grouped, the number of the sub-modules which are finally calculated by the upper layer controller and are grouped is allowed to be negative, and for the sub-modules which cannot generate negative pressure, if the number of the sub-modules which are calculated by the upper layer controller and are put into the sub-modules is negative, the number of the sub-modules which are put into the sub-modules needs to be adjusted, the number of the negative sub-modules which are put into the sub-modules becomes 0, and
and performing allocation, wherein K is the grouping number of the submodules which can only generate positive pressure.
In the voltage control method for the flexible direct current converter valve submodule, the normal submodule is a submodule capable of participating in normal switching, and does not include a submodule in a bypass state or a locking state.
In the voltage control method for the sub-module of the flexible direct current converter valve, the upper layer controller controls 1 or more bridge arm units.
In the method for controlling the voltage of the sub-module of the flexible direct current converter valve, the charging direction in the step (42) refers to a bridge arm current direction when the voltage of the sub-module rises, and the discharging direction refers to a bridge arm current direction when the voltage of the sub-module falls.
In the method for controlling the voltage of the submodule of the flexible direct current converter valve, the set value k of the average voltage deviation degree of the submoduleN≤40％。
The invention also provides a voltage control device of the submodule of the flexible direct current converter valve, which comprises a submodule grouping unit, a submodule number input calculation unit, a weight calculation unit, a deviation calculation unit, a submodule number input adjustment unit, a bridge arm current direction judgment unit and a submodule input number issuing unit, wherein,
the submodule grouping unit divides different types of submodules of each bridge arm of the converter valve into M groups, wherein M is a natural number and is more than or equal to 1, and the number of the submodules in each group is
Is a natural number, and is provided with a plurality of groups,
i is a grouping serial number, i is more than or equal to 1 and less than or equal to M, each group corresponds to one valve control device, each valve control device operates independently, and the number of the input submodules is sent to the valve control devices by an upper layer controller;
the sub-module number input unit is used for calculating the total number of the sub-modules to be input by the corresponding bridge arm
Wherein v isrefFor real-time reference waves, UCNA single sub-module voltage rating;
the weight calculation unit calculates the weight B of the governed valve control device according to the existing weight calculation methodiAnd the total number of the submodules which should be put into the bridge arm and is calculated by the submodule number input calculation unit
Calculating the number of sub-modules of each valve control device
Where round is a rounding function;
the deviation degree calculation unit is used for calculating the average voltage of the sub-modules of the governed valve control device
Relative to rated voltage UCNDegree of deviation k ofi，
And calculating the maximum deviation kmaxAnd minimum degree of deviation kminWhether the difference is larger than a set value k of the average voltage deviation of the submodules set by the valve control deviceN；
The bridge arm current direction judging unit is used for judging the direction of the collected bridge arm current;
the sub-module number input adjusting unit adjusts the number of sub-modules which need to be input into each valve control device and are calculated by the weight calculating unit according to the total sub-module input number calculated by the sub-module number input calculating unit, the weight of each valve control device and the deviation degree calculated by the deviation degree calculating unit, in combination with the bridge arm current direction calculated by the bridge arm current direction judging unit, generates the final sub-module input number in combination with the maximum normal sub-module number which can be input into operation of a corresponding bridge arm, and sends the final sub-module input number to each valve control device by the sub-module input number issuing unit.
And the submodule investment number issuing unit receives the final submodule investment number generated by the submodule number investment adjusting unit and issues the final submodule investment number to each valve control device.
In the foregoing flexible dc converter valve submodule voltage control apparatus, a specific method for adjusting the number of the submodules by the submodule number input adjusting unit is as follows:
(41) if k ismax-kmin＜kNKeeping the number of the submodules which are input by each valve control device and calculated by the number pre-input calculating unit unchanged; if k ismax-kmin≥kNThen the maximum deviation kmaxAnd minimum degree of deviation kminThe number of the sub-modules put into the corresponding valve control device needs to be adjusted according to the step (42);
(42) upper layer controller collects bridge arm current IarmAnd judging the direction when kmax-kmin≥kNIf the direction is the charging direction, the number of the added sub-modules of the valve control device corresponding to the maximum deviation degree is reduced to 0, and the number of the added sub-modules is reduced and increased to the number of the added sub-modules of the valve control device corresponding to the minimum deviation degree; if bridge arm current IarmIf the direction is the discharging direction, the number of the added sub-modules of the valve control device corresponding to the minimum deviation degree is reduced to 0, the number of the added sub-modules is reduced, and the number of the added sub-modules is increased to the number of the added sub-modules of the valve control device corresponding to the maximum deviation degree;
(43) if the number of the sub-modules put into the valve control device corresponding to the maximum or minimum deviation degree calculated in the step (42) exceeds the maximum number of the normal sub-modules put into the valve control device, the number of the sub-modules put into the valve control device corresponding to the maximum or minimum deviation degree is the maximum number of the normal sub-modules put into the valve control device, and the rest number of the sub-modules needing to be put into the valve control devices is distributed to other valve control devices according to the weights of other valve control devices except the device;
(44) and finally, the number of the sub-modules of each valve control device, which is calculated by the upper controller, is only capable of generating positive voltage groups, and the number of the sub-modules calculated by the upper controller satisfies the relation:
the sub-modules calculated by the upper layer controller satisfy the relational expression
When in use
When the sub-module which needs to be put into the group valve control device generates positive voltage, the sub-module generates positive voltage
When the sub-module required to be put into the block valve control device generates zero voltage, the sub-module is used for generating zero voltage
In time, the sub-modules needing to be put into the grouping valve control device are shown to generate negative voltage, and the number of the sub-modules put into the grouping valve control device satisfies the relational expression
In the voltage control device for the sub-modules of the flexible direct current converter valve, the sub-modules are of the same type or different types, and the sub-modules include a half-bridge sub-module shown in fig. 2, a full-bridge sub-module shown in fig. 3, and a full-bridge sub-module shown in fig. 4.
In the flexible voltage control device for the direct current converter valve sub-modules, the grouping principle is that one type of sub-modules are individually divided into one group or multiple groups, but each group of sub-modules only allows a single type of sub-module unit to exist.
In the voltage control device for the sub-module of the flexible dc converter valve, the grouping principle is as follows: the number of the normal sub-modules corresponding to each group is equal or unequal, and the number of the normal sub-modules in each group is allowed to dynamically change.
In the flexible direct current converter valve sub-module voltage control device, different types of sub-modules can generate different positive and negative voltages when put into operation, for sub-module groups capable of generating negative pressure, the number of the sub-modules put into the group, which is finally calculated by the upper layer controller, is allowed to be negative, for sub-module groups incapable of generating negative pressure, if the number of the sub-modules put into the group, which is calculated by the upper layer controller, is negative, the number of the sub-modules put into the group needs to be adjusted, the number of the negative sub-modules put into the group becomes 0, and the negative number is distributed by a valve control device capable of generating negative pressure according to weight.
In the voltage control device for the flexible direct current converter valve submodule, the normal submodule is a submodule capable of participating in normal switching, and does not include a submodule in a bypass state or a locking state.
In the voltage control device for the sub-module of the flexible direct current converter valve, the upper controller controls 1 or more bridge arm units.
In the above flexible dc converter valve sub-module voltage control device, the charging direction in the step (42) is a bridge arm current direction when the sub-module voltage rises, and the discharging direction is a bridge arm current direction when the sub-module voltage drops.
In the above flexible dc converter valve submodule voltage control apparatus, the submodule average voltage deviation degree set value kN≤40％。
The above embodiments are only for illustrating the technical idea of the present invention, and the protection scope of the present invention is not limited thereby, and any modifications made on the basis of the technical scheme according to the technical idea of the present invention fall within the protection scope of the present invention.
Claims (18)
1. A voltage control method for a flexible direct current converter valve submodule is characterized by comprising the following steps: the method comprises the steps of dividing different types of sub-modules of each bridge arm of the converter valve into M groups, wherein M is a natural number and is more than or equal to 1, and the number of the sub-modules in each group is
Is a natural number, and is provided with a plurality of groups,
i is a grouping serial number, i is more than or equal to 1 and less than or equal to M, each group corresponds to one valve control device, each valve control device operates independently, the number of the input submodules is issued to the valve control devices by an upper layer controller, and the calculation steps of the number of the input submodules are as follows:
(1) the upper layer controller calculates the total number of submodules to be put into corresponding bridge arms
Wherein v isrefFor real-time reference waves, UCNA single sub-module voltage rating;
(2) the upper layer controller calculates the total number of submodules to be put into the bridge arm according to the step (1)
And weight B of the governed valve control deviceiCalculating the number of sub-modules of each valve control device
Where round is a rounding function;
(3) the upper layer controller calculates the average voltage of the submodules of the governed valve control device
Relative to UCNDegree of deviation k ofi，
(4) Judging the maximum deviation k calculated by the upper controllermaxAnd minimum degree of deviation kminWhether the difference is larger than a set value k of the average voltage deviation of the submodules set by the valve control deviceNAccording to the deviation of the mean voltage of the submodules of the valve control device from the voltage nominal value of the individual submodulesWeight B of valve control deviceiAnd dynamically adjusting the number of the sub-modules required to be put into each valve control device in the bridge arm current direction, calculating the number of the final sub-modules put into operation by combining the maximum normal sub-modules which can be put into operation by the corresponding bridge arm, and sending the number of the final sub-modules to each valve control device.
2. The voltage control method of the flexible direct current converter valve submodule according to claim 1, wherein: the specific method for adjusting the number of the sub-modules in the step (4) is as follows:
(41) if k ismax-kmin<kNKeeping the number of the sub-modules put into each valve control device calculated in the step (2) unchanged; if k ismax-kmin≥kNThen the maximum deviation kmaxAnd minimum degree of deviation kminThe number of the sub-modules put into the corresponding valve control device needs to be adjusted according to the step (42);
(42) upper layer controller collects bridge arm current IarmAnd judging the direction when kmax-kmin≥kNWhen, if bridge arm current IarmIf the direction is the charging direction, the number of the added sub-modules of the valve control device corresponding to the maximum deviation degree is reduced to 0, and the number of the added sub-modules is reduced and increased to the number of the added sub-modules of the valve control device corresponding to the minimum deviation degree; if bridge arm current IarmIf the direction is the discharging direction, the number of the added sub-modules of the valve control device corresponding to the minimum deviation degree is reduced to 0, the number of the added sub-modules is reduced, and the number of the added sub-modules is increased to the number of the added sub-modules of the valve control device corresponding to the maximum deviation degree;
(43) if the number of the sub-modules put into the valve control device corresponding to the maximum deviation degree or the minimum deviation degree calculated according to the step (42) exceeds the maximum number of the normal sub-modules which can be put into the valve control device, the number of the sub-modules put into the valve control device corresponding to the maximum deviation degree or the minimum deviation degree is the maximum number of the normal sub-modules which can be put into the valve control device, and the number of the remaining sub-modules which need to be put into the valve control device is distributed to other valve control devices according to the weights of other valve control devices except the valve control device;
(44) and finally, the number of the sub-modules of each valve control device, which is calculated by the upper controller, is only capable of generating positive voltage groups, and the number of the sub-modules calculated by the upper controller satisfies the relation:
the sub-modules calculated by the upper layer controller satisfy the relational expression
When in use
When the sub-module which needs to be put into the group valve control device generates positive voltage, the sub-module generates positive voltage
When the sub-module required to be put into the block valve control device generates zero voltage, the sub-module is used for generating zero voltage
In time, the sub-modules needing to be put into the grouping valve control device are shown to generate negative voltage, and the number of the sub-modules put into the grouping valve control device satisfies the relational expression
3. The voltage control method of the flexible direct current converter valve submodule according to claim 1, wherein: the grouping principle is that one type of sub-module is individually grouped into one or more groups, but each group of sub-modules only allows a single type of sub-module to exist.
4. The voltage control method of the flexible direct current converter valve submodule according to claim 1, wherein: the grouping principle is as follows: the number of the normal sub-modules corresponding to each group is equal or unequal, and the number of the normal sub-modules in each group is allowed to dynamically change.
5. The voltage control method of the flexible direct current converter valve submodule according to claim 1, wherein: the sub-modules which can generate negative pressure are grouped, the number of the sub-modules which are finally calculated by the upper layer controller and are grouped into negative sub-modules is allowed to be negative, if the number of the sub-modules which can not generate negative pressure is calculated by the upper layer controller to be negative, the number of the sub-modules which are put into the sub-modules needs to be adjusted, the number of the sub-modules which are put into the sub-modules becomes 0, and the negative number is distributed by a valve control device which can generate negative pressure according to weight.
6. The voltage control method of the flexible direct current converter valve submodule according to claim 1, wherein: the normal sub-modules are sub-modules capable of participating in normal switching, and do not include sub-modules in bypass or locking states.
7. The voltage control method of the flexible direct current converter valve submodule according to claim 1, wherein: the upper layer controller controls 1 or more bridge arms.
8. The voltage control method of the flexible direct current converter valve submodule according to claim 2, characterized by comprising the steps of: in the step (42), the charging direction refers to a bridge arm current direction when the voltage of the sub-module rises, and the discharging direction refers to a bridge arm current direction when the voltage of the sub-module falls.
9. The voltage control method of the flexible direct current converter valve submodule according to claim 1, wherein: the set value k of the average voltage deviation of the submodulesN≤40％。
10. The utility model provides a flexible direct current converter valve submodule piece voltage control device which characterized in that: comprises a sub-module grouping unit, a sub-module number input calculation unit, a weight calculation unit, a deviation calculation unit, a sub-module number input adjustment unit, a bridge arm current direction judgment unit and a sub-module input number issuing unit, wherein,
the submodule grouping unit divides different types of submodules of each bridge arm of the converter valve into M groups, wherein M is a natural number and is more than or equal to 1, and the number of the submodules in each group is
Is a natural number, and is provided with a plurality of groups,
i is a grouping serial number, i is more than or equal to 1 and less than or equal to M, each group corresponds to one valve control device, each valve control device operates independently, and the number of the input submodules is sent to the valve control devices by an upper layer controller;
the sub-module number input calculation unit is used for calculating the total sub-module number to be input by the corresponding bridge arm
Wherein v isrefFor real-time reference waves, UCNA single sub-module voltage rating;
the weight calculation unit calculates the weight B of the governed valve control device according to the existing weight calculation methodiAnd inputting the total number of the submodules to be input into the bridge arm calculated by the calculation unit according to the number of the submodules
Calculating the number of sub-modules of each valve control device
Where round is a rounding function;
the deviation meterA calculation unit for calculating the average voltage of the sub-modules of the valve control device
Relative to UCNDegree of deviation k ofi，
And calculating the maximum deviation kmaxAnd minimum degree of deviation kminWhether the difference is larger than a set value k of the average voltage deviation of the submodules set by the valve control deviceN；
The bridge arm current direction judging unit is used for judging the direction of the collected bridge arm current;
the sub-module number input adjusting unit adjusts the number of sub-modules which need to be input into each valve control device and are calculated by the weight calculating unit according to the total sub-module input number calculated by the sub-module number input calculating unit, the weight of each valve control device and the deviation degree calculated by the deviation degree calculating unit, in combination with the bridge arm current direction calculated by the bridge arm current direction judging unit, generates the final sub-module input number in combination with the maximum normal sub-module number which can be input into operation of a corresponding bridge arm, and sends the final sub-module input number to each valve control device by the sub-module input number issuing unit;
and the submodule investment number issuing unit receives the final submodule investment number generated by the submodule number investment adjusting unit and issues the final submodule investment number to each valve control device.
11. The voltage control device of claim 10, wherein: the specific method for adjusting the number of the sub-modules by the sub-module number input adjusting unit comprises the following steps:
(41) if k ismax-kmin<kNKeeping the number of the submodules which are input by each valve control device and calculated by the input calculation unit unchanged; if k ismax-kmin≥kNThen the maximum deviation kmaxAnd minimum deviationDegree kminThe number of the sub-modules put into the corresponding valve control device needs to be adjusted according to the step (42);
(42) upper layer controller collects bridge arm current IarmAnd judging the direction when kmax-kmin≥kNWhen, if bridge arm current IarmIf the direction is the charging direction, the number of the added sub-modules of the valve control device corresponding to the maximum deviation degree is reduced to 0, and the number of the added sub-modules is reduced and increased to the number of the added sub-modules of the valve control device corresponding to the minimum deviation degree; if bridge arm current IarmIf the direction is the discharging direction, the number of the added sub-modules of the valve control device corresponding to the minimum deviation degree is reduced to 0, the number of the added sub-modules is reduced, and the number of the added sub-modules is increased to the number of the added sub-modules of the valve control device corresponding to the maximum deviation degree;
(43) if the number of the sub-modules put into the valve control device corresponding to the maximum deviation degree or the minimum deviation degree calculated according to the step (42) exceeds the maximum number of the normal sub-modules which can be put into the valve control device, the number of the sub-modules put into the valve control device corresponding to the maximum deviation degree or the minimum deviation degree is the maximum number of the normal sub-modules which can be put into the valve control device, and the number of the remaining sub-modules which need to be put into the valve control device is distributed to other valve control devices according to the weights of other valve control devices except the valve control device;
(44) and finally, the number of the sub-modules of each valve control device, which is calculated by the upper controller, is only capable of generating positive voltage groups, and the number of the sub-modules calculated by the upper controller satisfies the relation:
the sub-modules calculated by the upper layer controller satisfy the relational expression
When in use
When the voltage is positive, the submodule which needs to be put into the group valve control device generates positive voltageWhen is coming into contact with
When the sub-module required to be put into the block valve control device generates zero voltage, the sub-module is used for generating zero voltage
In time, the sub-modules needing to be put into the grouping valve control device are shown to generate negative voltage, and the number of the sub-modules put into the grouping valve control device satisfies the relational expression
12. The voltage control device of claim 10, wherein: the grouping principle is that one type of sub-module is individually grouped into one or more groups, but each group of sub-modules only allows a single type of sub-module to exist.
13. The voltage control device of claim 10, wherein: the grouping principle is as follows: the number of the normal sub-modules corresponding to each group is equal or unequal, and the number of the normal sub-modules in each group is allowed to dynamically change.
14. The voltage control device of claim 10, wherein: the sub-modules which can generate negative pressure are grouped, the number of the sub-modules which are finally calculated by the upper layer controller and are grouped into negative sub-modules is allowed to be negative, if the number of the sub-modules which can not generate negative pressure is calculated by the upper layer controller to be negative, the number of the sub-modules which are put into the sub-modules needs to be adjusted, the number of the sub-modules which are put into the sub-modules becomes 0, and the negative number is distributed by a valve control device which can generate negative pressure according to weight.
15. The voltage control device of claim 10, wherein: the normal sub-modules are sub-modules capable of participating in normal switching, and do not include sub-modules in bypass or locking states.
16. The voltage control device of claim 10, wherein: the upper layer controller controls 1 or more bridge arms.
17. The voltage control device of claim 11, wherein: in the step (42), the charging direction refers to a bridge arm current direction when the voltage of the sub-module rises, and the discharging direction refers to a bridge arm current direction when the voltage of the sub-module falls.
18. The voltage control device of claim 10, wherein: the set value k of the average voltage deviation of the submodulesN≤40％。
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