CN110867885A - Submodule alternation control method of direct current energy consumption device - Google Patents
Submodule alternation control method of direct current energy consumption device Download PDFInfo
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Abstract
The invention discloses a submodule alternation control method of a direct current energy consumption device, which comprises the following steps: calculating the energy absorption equivalent value of each sub-module in the control period; sorting the energy absorption equivalent values of the sub-modules according to a preset sorting algorithm; and determining the priority investment right of the sub-modules according to the preset rotation limit value. According to the control method provided by the invention, the energy absorption equivalent values are introduced and used as judgment indexes, then the energy absorption equivalent values of the sub-modules in the period are sequenced according to a preset algorithm, and the priority investment right of the sub-modules is determined through the preset rotation limit value, so that the uniform distribution of the total energy in all the modules can be more reliably ensured, and a better control effect is achieved.
Description
Technical Field
The invention relates to the field of offshore wind power, in particular to a submodule alternation control method of a direct current energy consumption device.
Background
Wind power generation is one of the most mature and potential-developed power generation modes in new energy power generation technology, and is an important solution for green and low-carbon energy advocation. For long-distance offshore wind power, a voltage source type high-voltage direct-current transmission technology is mainly adopted for power transmission and grid connection, when an alternating-current power grid on the side of a receiving end converter station has a low-voltage fault, the active power transmitted outwards by the receiving end converter station is reduced, however, due to the hysteresis of offshore wind field regulation, the active power injected into a system cannot be reduced immediately, the total input power of the system is greater than the output power of the system, and overvoltage damage to capacitive equipment is caused.
Disclosure of Invention
In view of this, the embodiment of the present invention provides a submodule rotation control method for a dc energy consumption device, which solves the problem in the prior art that capacitive equipment is damaged due to overvoltage caused by the fact that the total input power of a system is greater than the output power of the system.
The embodiment of the invention provides a submodule alternation control method of a direct current energy consumption device, which comprises the following steps: calculating the energy absorption equivalent value of each sub-module in the control period; sorting the energy absorption equivalent values of the sub-modules according to a preset sorting algorithm; and determining the priority investment right of the sub-modules according to the preset rotation limit value.
Optionally, the energy absorption equivalent value of each sub-module in the control period is calculated by the following formula:
wherein, EDEi(y) represents the energy absorption equivalent value of the ith module within the control period of the ith, Ei(y) the sum of the absorbed energy of the i-th module up to the y-th control period, UcRated voltage of capacitor, ImaxIs the maximum current of the energy-consuming device, TctlIndicating the duration of one control period.
Optionally, the sum of the absorbed energy of each submodule up to the current control period is calculated by the following formula:
wherein E isi(y) the sum of absorbed energy of the ith module in the control period from the time point when the ith module is cut off to the time point when the ith module is in the control period, wherein i represents the number of the sub-module (i is 1,2,3, …, N), y represents the number of the control period (y is 1,2,3, …, j), k (y) represents the per-unit value of the absorbed power of the energy consumption device in the control period of the ith module, and the value range of the per-unit value is 0-1, and T is within the range of TctlIndicating the duration of a control cycle, Si(y) switching command, U, of the ith module T1 at the y control cyclecRated voltage of capacitor, ImaxThe maximum current of the energy consuming device.
Optionally, the step of determining the priority of the sub-module according to the preset rotation limit includes: calculating the switching frequency of the switch according to the module rotation limit value of each control period; calculating the variable quantity of the number of input sub-modules caused by the power change in the adjacent control periods according to the variable quantity of the per-unit value of the absorbed power of the direct-current energy consumption device; and determining the priority investment right of the submodules according to the variable quantity of the number of the investment submodules.
Optionally, the switching frequency of the switch is calculated by the following formula:
fT1＝NBLN/NTctl，
wherein f isT1Indicating the switching frequency, N, of the switches in the control cycleBLNIndicating the rotation limit, N the number of submodules, TctlIndicating the duration of one control period.
Alternatively, the amount of change in the number of input sub-modules is calculated by the following formula:
ΔNin＝round[N·k(j-1)]-round[N·k(j)]，
wherein, Δ NinThe method comprises the steps of representing the variable quantity of the number of input submodules caused by power change in adjacent control periods, representing the number of the submodules by N, and representing the per unit value of absorbed power of an energy consumption device in the jth control period by k (j), wherein the value range is 0-1.
Optionally, the step of determining the priority investment right of the sub-modules according to the variation of the number of investment sub-modules includes: the sub-modules are increased according to the energy absorption equivalent valueSorting the data when the data is small; judging whether the variable quantity of the number of the input sub-modules is equal to 0 or not; when the variation is equal to 0, the energy absorption equivalent value which is already put into the sub-module is ranked in the top NBLNCutting out individual sub-modules, and arranging the energy absorption equivalent values of the cut-out sub-modules at the top NBLNAnd (5) inputting each submodule.
Optionally, the submodule rotation control method of the dc energy consumption device further includes: when the variation is larger than 0, arranging the energy absorption equivalent value which is already input into the sub-module at the top NBLNCutting out individual sub-modules, and arranging the energy absorption equivalent values of the cut-out sub-modules at the top NBLNSubmodule of N plus Δ NinAnd (5) inputting each submodule.
Optionally, the submodule rotation control method of the dc energy consumption device further includes: when the variation is less than 0, the first N in the energy absorption equivalent value of the sub-module is addedBLNSubmodule of N minus Δ NinCutting out each submodule, and cutting out N of each submoduleBLNAnd (5) inputting each submodule.
The technical scheme of the invention has the following advantages:
1. according to the submodule alternation control method of the direct current energy consumption device, the energy absorption equivalent value is introduced and is used as a judgment index, then the energy absorption equivalent values of the submodules in the period are sequenced according to a preset algorithm, and the priority investment right of the submodules is determined through the preset alternation limit value, so that the total energy can be more reliably ensured to be uniformly distributed in all the submodules, and a better control effect is achieved.
2. According to the submodule alternation control method of the direct current energy consumption device, the switching frequency is controlled by changing the module alternation limit value, once the alternation limit value is selected, the switching frequency of a device is not changed along with the working condition, the device selection and loss analysis of the energy consumption device designed in the early stage are facilitated, the priority input right of the submodule is determined according to the variable quantity of the input submodule quantity, the occupied storage space and the calculation resource are less during the execution, and the stability of the system is more facilitated.
Drawings
In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly described below, and it is obvious that the drawings in the following description are some embodiments of the present invention, and other drawings can be obtained by those skilled in the art without creative efforts.
Fig. 1 is a schematic diagram of a hybrid dc energy dissipation device according to an embodiment of the present invention;
fig. 2 is a flowchart of a specific example of a sub-module rotation control method of a dc energy consuming device according to an embodiment of the present invention;
FIG. 3 is a flow diagram illustrating one embodiment of determining priority for a sub-module according to the present invention;
FIG. 4 is a flow diagram illustrating one embodiment of determining priority for a sub-module according to the present invention;
fig. 5 is a flowchart of a specific example of determining priority investment right of a sub-module according to a variation of the number of investment sub-modules according to the embodiment of the present invention;
fig. 6 is a simulation result diagram of a submodule rotation control method of a dc energy consumption device according to an embodiment of the present invention.
Detailed Description
The technical solutions of the present invention will be described clearly and completely with reference to the accompanying drawings, and it should be understood that the described embodiments are some, but not all embodiments of the present invention. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
In addition, the technical features involved in the different embodiments of the present invention described below may be combined with each other as long as they do not conflict with each other.
The embodiment of the invention provides a submodule alternation control method of a current energy consumption device, which can be suitable for submodule alternation control of a hybrid direct current energy consumption device shown in figure 1, wherein the hybrid direct current energy consumption device is formed by connecting N Submodules (SM) and a centralized resistor (R) in series. The structure of each submodule is shown in a dotted frame in the figure and consists of 2 IGBTs (T1 and T2), 1 energy storage capacitor (C), 1 distributed resistor (r) and 4 diodes.
When T1 is turned off (T1 is 0), the sub-module output voltage is the capacitor voltage, which is called the on state; when T1 is turned on (T1 ═ 1), the sub-module output voltage is 0, which is referred to as the off state.
The basic working principle of the energy consumption device is as follows:
when the system has no fault, the absorbed power P of the energy consumption device is 0, at the moment, T1 and T2 in all the modules are turned off, all the capacitors in the series support direct-current voltage at two ends of a direct-current side, the voltage drop at two ends of a concentration resistor R is 0, and the energy consumption device has no power consumption. DC bus line voltage UdcSubmodule capacitor voltage UcThe number N of the sum submodules satisfies the following relationship
When the system has a low-voltage fault of a receiving-end alternating current power grid, the energy consumption device is started to absorb surplus power, the power needing to be absorbed is P, and the current flowing through the energy consumption device is I P/UdcThe voltage across the lumped resistor is Ures＝RP/UdcThus obtaining the sum of all sub-module output voltages as Uout＝Udc-UresAnd then the number N of the input modules at the moment can be calculatedin
Therefore, by controlling the number of input modules (i.e., the number of modules turned on by T1), the voltage across the distributed resistor R can be controlled, and the power absorbed by the energy consuming device can be controlled. On the other hand, when current flows through the sub-module capacitors, the capacitance voltage rises, so that each sub-module is provided with a switch T2 and a distribution resistor r, and when the capacitance voltage is higher than the upper limit value, T2 is turned on and discharges through the distribution resistor r.
When the energy consumption device needs to absorb the specified power P, although the number N of the modules needing to be invested can be calculated through the formula (2)inBut which N among all N submodulesinThe sub-modules are invested and still not determined. In fact, this NinThe sub-modules that are put into use need to be rotated continuously because the capacitors of the modules that are put into use will be charged, in order to maintain the capacitor voltage constant, the switches T2 of the modules will be turned on and discharged through the distribution resistors r and all converted into heat of the resistors, if the sub-modules that are always fixed are put into use, the internal resistors will be damaged due to the over-temperature rise, and therefore the sub-modules need to be switched in turn to ensure that the absorbed power is uniformly distributed to the resistors of each sub-module.
It should be noted that, in the embodiment of the present invention, the hybrid dc energy consumption device is taken as an example for description, and in practical applications, the present invention may also be applied to other energy consumption devices, and the present invention is not limited thereto.
Specifically, as shown in fig. 2, the submodule rotation control method of the dc energy consumption device specifically includes:
step S1: and calculating the energy absorption equivalent value of each sub-module in the control period.
In the embodiment of the present invention, as shown in fig. 3, an offshore wind power system based on a voltage source converted high voltage direct current (VSC-HVDC) voltage source based high voltage direct current transmission technology mainly includes: an Offshore Wind Farm (OWF), a sending end converter Station (SEC), a receiving end converter station (REC), a submarine dc cable, and other auxiliary equipment. When the alternating current network on the receiving end converter station side has a low-voltage fault, the active power transmitted outwards by the receiving end converter station is reduced, however, due to the hysteresis of offshore wind field regulation, the active power injected into the system cannot be reduced immediately, so that the total input power of the system is greater than the output power of the system, and overvoltage damage to capacitive equipment is caused. The direct current energy dissipation device is connected in parallel to two ends of the direct current side on the land, and has the functions of absorbing surplus power of the system, maintaining the stability of the voltage of the system and avoiding overvoltage damage when the situation occurs.
In the submodule alternation control method of the direct current energy consumption device, the energy absorption equivalent value of each submodule in the control period can be calculated through a formula (3), and the energy absorption equivalent value is an index for measuring the absorbed energy of a power unit in the energy consumption device. Since the actual absorbed energy value of the power cell is large and increases rapidly with time, if the actual energy value is used directly for iteration and calculation, the calculation module load pressure is large and the internal counter will overflow quickly, thus introducing the concept of energy absorption equivalent. The energy absorption capacity of the power unit is different from the actual energy absorption capacity by a constant coefficient in value, and the increment per period of the energy absorption capacity is in the range of 0-1, so that the energy absorption capacity of the power unit can be represented on one hand, and the energy absorption capacity of the power unit is small in value and small in increment per period on the other hand, the calculation is convenient, and overflow cannot occur.
Wherein, EDEi(y) represents the energy absorption equivalent value of the ith module within the control period of the ith, Ei(y) represents the sum of the absorbed energy of the i-th module from the cut-off to the y-th control period, UcRepresenting the rated voltage of the capacitor, ImaxIndicating the maximum current, T, of the energy consuming devicectlIndicating the duration of one control period.
When the energy absorption equivalent value of each submodule in the control period is calculated, the sum of the energy absorbed by each submodule in the current control period is calculated through a formula (4):
wherein E isi(y) represents the sum of the energy absorbed by the ith module in the control period from the time point when the ith module is turned off to the time point when the ith module is turned on, i represents the number of the submodule (i is 1,2,3, …, N), and y represents the number of the control period (y is 1)2,3, …, j), k (y) represents the absorbed power per unit value of the energy consumption device in the y control period, the value range is 0-1, TctlIndicating the duration of a control cycle, Si(y) switching command, U, of the ith module T1 at the y control cyclecRepresenting the rated voltage of the capacitor, ImaxRepresenting the maximum current of the consumer.
Example I of the present inventionmaxIs equal to UdcR, due to U in the formulac、Imax、TctlAll are constants, the concept of "energy absorption equivalent (EDE)" is introduced while omitting constant values, and according to the formula (3) and the formula (4), the absorption equivalent value can be obtained as shown in the formula (5):
as can be seen, each submodule energy absorption equivalent EDEiThe size of (y) represents the actual energy absorption of each submodule, and the energy absorbed by the submodule is finally converted into heat of internal distributed resistors, so that the heat loss on the internal resistors of each submodule can be ensured to be the same as long as the energy absorption equivalent value of each submodule is ensured to be the same.
Step S2: and sequencing the energy absorption equivalent values of the sub-modules according to a preset sequencing algorithm.
In the embodiment of the invention, according to a preset sequencing algorithm, the energy absorption equivalent value EDE accumulated when each module cuts off the current control period can be calculated in each control periodi(y) after, then for all EDEsiAnd (y) sorting values, wherein a large value indicates that the module has been put into more time and has larger loss and should be cut off preferentially, and a small value indicates that the module has been put into less time and has smaller loss and should be put into preferentially. Due to the energy absorption equivalent value EDEi(y) the increment per cycle is at most 1, so that the storage space occupied in the control and protection program is small, and the control and protection program can be accumulated for a long time without overflowing, which is also the main reason for introducing the energy absorption equivalent.
It should be noted that the preset sorting algorithm in the embodiment of the present invention only has an effect of sorting all the calculated energy absorption equivalent values, and any sorting algorithm may be selected according to actual needs, which is not limited to the present invention.
Step S3: and determining the priority investment right of the sub-modules according to the preset rotation limit value.
In the present example, though by sequencing EDEs per cycleiThe (y) value may determine which modules have priority, but if all priority modules are rotated every cycle, the switching frequency of T1 will tend to be high and the switching losses will tend to be large. Therefore, by introducing the concept of "rotation limit", the number of modules rotating per cycle can be limited, and N can be switched at most per cycleBLNThe sub-module not only limits the switching frequency of T1, but also can reduce EDEiThe sequence number of (y) greatly shortens the execution time of the program and the occupied resources.
According to the submodule alternation control method of the direct current energy consumption device, the energy absorption equivalent value is introduced and is used as a judgment index, then the energy absorption equivalent values of the submodules in the period are sequenced according to a preset algorithm, and the priority investment right of the submodules is determined through the preset alternation limit value, so that the total energy can be more reliably ensured to be uniformly distributed in all the submodules, and a better control effect is achieved.
In a specific embodiment, as shown in fig. 4, the process of executing step S3 may specifically include the following steps:
step S31: and calculating the switching frequency of the switch according to the module rotation limit value of each control period.
In the embodiment of the invention, the total switching times of all the sub-modules are composed of two parts, wherein the first part is the fixed number N of the alternate modules in each periodBLNThe second part is the additional number of switching times N due to power variationsaddTherefore, the switching frequency up to the jth control period T1 is:
fT1(j)＝[j·NBLN+Nadd]/jNTctl(6)
when j is larger, NaddCompared with j and NBLNVery little and negligible, so that the switching frequency of T1 is obtained as:
fT1＝NBLN/NTctl(7)
it can be seen that, since the average switching frequency of all the switching devices is determined before leaving the factory, the limit N can be rotated by the control moduleBLNThe switching frequency is controlled and does not change along with the working condition, so that the loss calculation and analysis after the design and the model selection of the device in the early stage are facilitated, the switching frequency is controlled not to exceed the average switching frequency of the device when the device leaves a factory, and the service life of the switch is ensured.
Step S32: and calculating the variable quantity of the number of the input sub-modules caused by the power change in the adjacent control periods according to the variable quantity of the per-unit value of the absorbed power of the direct-current energy consumption device.
In the embodiment of the invention, the variable quantity of the number of the input sub-modules caused by the power change in the adjacent control period is calculated according to the variable quantity of the per-unit value of the absorbed power of the direct-current energy consumption device, namely the change of the number of the input modules caused by the change of the absorption instruction (namely k (y)) of the energy consumption device in the current control period compared with the previous control period. The variation of the number of input submodules is calculated by equation (8):
ΔNin＝round[N·k(j-1)]-round[N·k(j)](8)
wherein, Δ NinThe method comprises the steps of representing the variable quantity of the number of input submodules caused by power change in adjacent control periods, representing the number of the submodules by N, and representing the per unit value of absorbed power of an energy consumption device in the jth control period by k (j), wherein the value range is 0-1. The per unit value of the absorbed power is one of relative units, and the per unit value is a numerical value marking method commonly used in power system analysis and engineering calculation and represents a relative value of each physical quantity and parameter. Since the famous values of different voltage levels cannot be calculated together, the famous values need to be converted to the same voltage level, and the conversion times can be reduced by taking the per unit value as an intermediate quantity.
Step S33: and determining the priority investment right of the submodules according to the variable quantity of the number of the investment submodules. In practical application, the priority investment right of the sub-modules is determined according to the variable quantity of the investment sub-modules and then according to the absorption energy equivalent values of all the sub-modules in the sequence.
In a specific embodiment, as shown in fig. 5, the process of executing step S33 may specifically include the following steps:
step S331: the sub-modules are ordered according to the energy absorption equivalent value from large to small. To determine the specific inputs of the sub-modules, the energy absorption equivalent values are ordered from large to small. It should be noted that, in the embodiment of the present invention, the energy absorption equivalent values are sorted from large to small, and in practical applications, the energy absorption equivalent values may also be sorted from small to large, and are set according to practical needs, which is not limited to the present invention.
Step S332: it is determined whether the amount of change in the number of input sub-modules is equal to 0.
In the embodiment of the invention, Delta N isinThere may be three results compared to 0: delta NinWhen the power consumption is equal to 0, the absorbed power of the energy consumption device in two adjacent periods is unchanged, and the number of input modules is unchanged; delta NinIf the power is more than 0, the absorbed power is reduced, and the number of input modules is increased; delta NinIf < 0, the absorbed power becomes large and the number of input modules becomes small.
Step S333: when the variation is equal to 0, the energy absorption equivalent value which is already put into the sub-module is ranked in the top NBLNCutting out each sub-module, and arranging the energy absorption equivalent value of the cut-out sub-module in the last NBLNAnd (5) inputting each submodule.
In the embodiment of the invention, when the variation is equal to 0, the variation indicates that the absorbed power of the energy consumption device in two adjacent periods is unchanged, and the number of input modules is unchanged, so that the first N in the energy absorption equivalent values after the arrangement is required to be arranged in the sequenceBLNCutting off each submodule, and then arranging the energy absorption equivalent values of all the submodules which are not input in the last NBLNAnd (5) inputting each submodule.
Step S334: when the variation is larger than 0, arranging the energy absorption equivalent value which is already put into the sub-module at the top NBLNCutting out each sub-module, and arranging the energy absorption equivalent value of the cut-out sub-module in the top NBLNSubmodule of N plus Δ NinAnd (5) inputting each submodule.
In the embodiment of the invention, when the variation is greater than 0, the energy consumption device in two adjacent periods absorbs less power, and the number of input modules is increased, so that the front N in the energy absorption equivalent values after the arrangement sequence needs to be arrangedBLNCutting off each submodule, and then arranging the energy absorption equivalent values of all the submodules which are not input in the last NBLNSubmodule of N plus Δ NinAnd (5) inputting each submodule.
Step S335: when the variation is less than 0, the first N in the energy absorption equivalent value of the sub-module is addedBLNSubmodule of N minus Δ NinCutting out each submodule, and cutting out N of each submoduleBLNAnd (5) inputting each submodule.
In the embodiment of the invention, when the variation is smaller than 0, it indicates that the absorbed power of the energy consumption device in two adjacent periods is increased and the number of input modules is reduced, so that the top N of the energy absorption equivalent values after the ordering is required to be rankedBLNSubmodule of N minus Δ NinCutting off each submodule, and then arranging the energy absorption equivalent values of all the submodules which are not input in the last NBLNAnd (5) inputting each submodule.
In practical application, parameters are set according to the simulation model parameters in table 1, simulation calculation is performed, and the obtained simulation oscillogram is shown in fig. 6. Wherein, the (a), (b), (c) and (d) are the voltage per unit value of the AC power network at the receiving end, the energy absorbed by the energy consumption device, the energy absorbed by each sub-module and the total switching times of the switching device respectively. It can be seen from (a) that when t is 0.5s, a low-voltage fault occurs in the ac power grid, the voltage will be 0 from the rated value, and at this time, the energy consumption device is started, and after 1s, the voltage is restored from 0 to the rated value, and when t is 2.5s, the fault is cleared, and the energy consumption device is exited; in this process, the energy absorbed by the energy consuming device is shown as (b), which varies with the voltage; as can be seen from (c), the energy absorbed by each module is uniform, and the energy absorbed by the energy consumption device is uniformly distributed to each moduleIn each module, the effectiveness of the control method provided by the invention is proved; from (d), it can be seen that, during the period from t being 1.5s to t being 2.5s, the switching times of the switching device increases in a proportional function, the slope of the switching device is fixed, and it is proved that the switching frequency does not change with the operating condition, the average switching frequency is 251Hz within the 1s, and N in the parameter table is used asBLN＝10、N＝400、TctlSubstitution of 100us into (7) gives fT1At 250Hz, it can be seen that the actual and calculated values are very close and the switching frequency is very low.
TABLE 1
According to the submodule alternation control method of the direct current energy consumption device, the switching frequency is controlled by changing the module alternation limit value, once the alternation limit value is selected, the switching frequency of a device is not changed along with the working condition, the device selection and loss analysis of the energy consumption device designed in the early stage are facilitated, the priority input right of the submodule is determined according to the variable quantity of the input submodule quantity, the occupied storage space and the calculation resource are less during the execution, and the stability of the system is more facilitated.
It should be understood that the above examples are only for clarity of illustration and are not intended to limit the embodiments. Other variations and modifications will be apparent to persons skilled in the art in light of the above description. And are neither required nor exhaustive of all embodiments. And obvious variations or modifications therefrom are within the scope of the invention.
Claims (9)
1. A submodule alternation control method of a direct current energy consumption device is characterized by comprising the following steps:
calculating the energy absorption equivalent value of each sub-module in the control period;
sorting the energy absorption equivalent values of the sub-modules according to a preset sorting algorithm;
and determining the priority investment right of the sub-modules according to the preset rotation limit value.
2. The submodule alternation control method of the direct current energy consumption device as claimed in claim 1, wherein the energy absorption equivalent value of each submodule in the control period is calculated by the following formula:
wherein, EDEi(y) represents the energy absorption equivalent value of the ith module within the control period of the ith, Ei(y) represents the sum of the absorbed energy of the i-th module from the cut-off to the y-th control period, UcRepresenting the rated voltage of the capacitor, ImaxIndicating the maximum current, T, of the energy consuming devicectlIndicating the duration of one control period.
3. The method for controlling submodule rotation of a dc energy consumption device according to claim 2, wherein the sum of the energy absorbed by each submodule till the current control period is calculated by the following formula:
wherein E isi(y) represents the sum of the absorbed energy of the ith module in the ith control period, i represents the number of the sub-module (i is 1,2,3, …, N), y represents the number of the control period (y is 1,2,3, …, j), k (y) represents the absorbed power per unit value of the energy consumption device in the yth control period, and the value range is 0-1, TctlIndicating the duration of a control cycle, Si(y) switching command, U, of the ith module T1 at the y control cyclecRepresenting the rated voltage of the capacitor, ImaxRepresenting the maximum current of the consumer.
4. The submodule alternation control method of the dc energy consumption device according to claim 3, wherein the step of determining the priority of the submodule according to the preset alternation limit value comprises:
calculating the switching frequency of the switch according to the module rotation limit value of each control period;
calculating the variable quantity of the number of input sub-modules caused by the power change in the adjacent control periods according to the variable quantity of the per-unit value of the absorbed power of the direct-current energy consumption device;
and determining the priority investment right of the submodules according to the variable quantity of the number of the investment submodules.
5. The submodule alternation control method for the direct current energy consumption device as claimed in claim 4, wherein the switching frequency of the switch is calculated by the following formula:
fT1＝NBLN/NTctl，
wherein f isT1Indicating the switching frequency, N, of the switches in the control cycleBLNIndicating the rotation limit, N the number of submodules, TctlIndicating the duration of one control period.
6. The submodule alternation control method of the direct current energy consumption device as claimed in claim 4, wherein the variation of the number of input submodules is calculated by the following formula:
ΔNin＝round[N·k(j-1)]-round[N·k(j)]，
wherein, Δ NinThe method comprises the steps of representing the variable quantity of the number of input submodules caused by power change in adjacent control periods, representing the number of the submodules by N, and representing the per unit value of absorbed power of an energy consumption device in the jth control period by k (j), wherein the value range is 0-1.
7. The submodule alternation control method of the direct current energy consumption device according to claim 4, wherein the step of determining the priority investment right of the submodule according to the variation of the number of the investment submodules comprises:
sequencing the sub-modules from large to small according to the energy absorption equivalent value;
judging whether the variable quantity of the number of the input sub-modules is equal to 0 or not;
when the variation is equal to 0, the energy absorption equivalent value which is already put into the sub-module is ranked in the top NBLNCutting out each sub-module, and arranging the energy absorption equivalent value of the cut-out sub-module in the last NBLNAnd (5) inputting each submodule.
8. The submodule rotation control method for the direct current energy consumption device according to claim 6, further comprising:
when the variation is larger than 0, arranging the energy absorption equivalent value which is already input into the sub-module at the top NBLNCutting out individual sub-modules, and arranging the energy absorption equivalent values of the cut-out sub-modules at the top NBLNSubmodule of N plus Δ NinAnd (5) inputting each submodule.
9. The submodule rotation control method for the direct current energy consumption device according to claim 6, further comprising:
when the variation is less than 0, the first N in the energy absorption equivalent value of the sub-module is addedBLNSubmodule of N minus Δ NinCutting out each submodule, and cutting out N of each submoduleBLNAnd (5) inputting each submodule.
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