CN114792971A - Grouping centralized direct current energy consumption device for optimizing direct current voltage control and control method - Google Patents

Abstract

The invention belongs to the field of direct current transmission, and relates to a grouping centralized direct current energy consumption device, a control method and a readable medium for optimizing direct current voltage control. The problem of large direct-current voltage switching spike of the centralized direct-current energy consumption device is effectively solved through the external parallel capacitor branch, and the steady-state fluctuation amplitude of direct-current voltage during the action period of the centralized direct-current energy consumption device is effectively reduced through the grouping arrangement structure and the grouping control strategy, so that the direct-current voltage control effect of the centralized direct-current energy consumption device is obviously optimized.

Description

Grouped centralized DC energy consumption device and control method for optimized DC voltage control

technical field

The invention relates to a grouped centralized direct current energy consumption device, a control method and a readable medium for optimizing direct current voltage control, belonging to the field of direct current power transmission, in particular to the design of a flexible direct current transmission system for offshore wind power.

Background technique

Flexible DC transmission is the optimal technical solution for large-capacity, long-distance offshore wind power grid connection. In order to solve the power surplus problem after the AC power grid at the receiving end of the offshore wind power flexible DC system fails, a DC energy consumption device with flexible and controllable power consumption must be introduced to realize fault ride-through. The centralized DC energy consumption device is composed of cascaded sub-modules and centralized The resistors arranged in series are favored because of their compact structure, simple control, no need to configure a water cooling system, and low cost. However, during the switching process of the centralized DC energy consumption device, the whole switching of the energy consumption mode is realized by hard switching on/off of all power devices, the power shock is large, and the control effect is not ideal, which often leads to large The DC voltage fluctuates, and the device is prone to large switching peaks on the inter-pole DC voltage when the device is turned on/off. Frequent shocks to related electrical equipment may seriously affect the safety of system operation.

SUMMARY OF THE INVENTION

In view of the above problems, the purpose of the present invention is to provide a grouped centralized DC energy consumption device, a control method and a readable medium for optimizing DC voltage control, which effectively solve the problem of DC energy consumption of the centralized DC energy consumption device through an external parallel capacitor branch. For the problem of large voltage switching peaks, the steady-state fluctuation amplitude of DC voltage during the operation of the centralized DC energy consumption device is effectively reduced by using the grouping arrangement structure and grouping control strategy, thereby significantly optimizing the DC voltage control effect of the centralized DC energy consumption device. .

In order to achieve the above purpose, the present invention proposes the following technical solutions: a grouped centralized DC energy consumption device for optimizing DC voltage control, the centralized DC energy consumption device is connected between the positive and negative electrodes of the DC, and includes two symmetrical upper and lower The upper and lower groups both include resistors and a number of energy-consuming modules, each energy-consuming module is connected in series, and is connected in series with the resistors, and the upper and lower groups are respectively connected in parallel with a capacitor, which is grounded through the connections of the upper and lower groups.

Further, the energy consumption module includes a P-type field effect transistor and a diode connected in reverse parallel with it.

Further, at the moment when the energy-consuming module is switched on, the parallel capacitor discharges to the energy-consuming module to suppress the peak of DC voltage input; at the moment when the energy-consuming module is switched off, the surplus power charges the parallel capacitor, thereby suppressing the DC voltage from cutting out the peak.

Further, when the two groups of energy dissipation modules are both switched on, the power of the energy dissipation branch is P _N , and the discharge power of the capacitor is P _N -△ P ; when the two groups of energy dissipation modes are both switched out, the power of the energy dissipation branch is 0, the capacitor discharge power is △ P ; when one group of energy-consuming modules is put in and the other group of energy-consuming modules is quickly cut out, the power of the energy-consuming branch is 1/2 P _N , if △ P < 1/2 P _N then At this time, the discharge power of the capacitor is 1/2 P _N - △ P , if △ P > 1/2 P _N , then the charging power of the capacitor is △ P- 1/2 P _N , if △ P= 1/2 P _N then At this time, the capacitor has no charge and discharge power.

Further, the maximum steady-state DC voltage fluctuation of the grouped centralized DC energy consumption device is:

Among them, U is the steady-state DC voltage, C is the equivalent capacitance, and T is the unit carrier period.

The invention also discloses a control method of a grouped centralized DC energy consumption device for optimizing DC voltage control, using any of the above grouped centralized DC energy consumption devices, including the following steps: based on a DC voltage reference value, through proportional integration Control the duty cycle a that generates the fast input of the energy consumption mode; during the enabling period of the DC energy consumption device, make the carrier phase of the upper and lower groups of energy consumption modules differ by 180°; Compare and generate turn-on or turn-off commands for the energy-consuming module.

Further, when the duty cycle a is greater than the carrier, the energy-consuming modules of all sub-modules in the corresponding group are turned on, and the energy-consuming modules are turned on quickly; when the duty cycle a is smaller than the carrier, the energy consumption of all sub-modules in the corresponding group is turned off. module, so that the energy consumption mode quickly exits.

Further, the higher the actual value of the DC voltage, the larger the duty cycle a.

Further, the carrier is a triangular carrier, the upper and lower limits of the triangular carrier are 1 and 0 respectively, and the frequency of the triangular carrier is determined according to the switching frequency of the energy consuming module.

The present invention also discloses a computer-readable storage medium, where a computer program is stored on the computer-readable storage medium, and the computer program is executed by a processor to realize any one of the above-mentioned optimized DC voltage control grouped centralized DC energy consumption devices. Control Method.

The present invention has the following advantages due to the adoption of the above technical solutions: the present invention provides a topology structure and a control method of a grouped centralized DC energy consumption device that optimizes the DC voltage control effect. The problem of large DC voltage switching peaks in the centralized DC energy consumption device, the use of grouping structure and group control strategy effectively reduces the steady-state fluctuation range of the DC voltage during the operation of the centralized DC energy consumption device, and significantly optimizes the centralized DC energy consumption. The DC voltage control effect of the device has great practical value and broad application prospects in the field of offshore wind power transmission via flexible DC.

Description of drawings

1 is a schematic structural diagram of a grouped centralized DC energy consumption device for optimizing DC voltage control according to an embodiment of the present invention;

2 is a schematic diagram of a control method of a grouped centralized DC energy consumption device in an embodiment of the present invention, in the figure, Udc is the actual DC operating voltage; Udcref is the DC reference voltage; a is the duty cycle of the fast input of the energy consumption mode; is the switching command of the upper group of DC energy-consuming devices; f2 is the switching command of the lower group of DC energy-consuming devices;

3 is a schematic diagram of a carrier and a duty cycle in an upper group of centralized DC energy consumption devices in an embodiment of the present invention;

4 is a schematic diagram of a carrier and a duty cycle in a lower group of centralized DC energy-consuming devices in an embodiment of the present invention;

5 is a schematic diagram of switching commands of the upper and lower groups of DC energy-consuming devices when the duty cycle a<1/2 in an embodiment of the present invention;

6 is a schematic diagram of switching commands of the upper and lower groups of DC energy-consuming devices when the duty ratio a=1/2 in an embodiment of the present invention;

7 is a schematic diagram of switching commands of the upper and lower groups of DC energy-consuming devices when the duty ratio a>1/2 in an embodiment of the present invention;

FIG. 8 is a DC voltage waveform during the operation of the DC energy consumption device in the case of a failure of the receiving-end AC system when the surplus power of the system is 1100 MW according to an embodiment of the present invention;

FIG. 9 is the DC voltage waveform during the operation of the DC energy consumption device when the receiver AC system failure occurs when the system surplus power is 550 MW according to an embodiment of the present invention;

FIG. 10 is a DC voltage waveform during the operation of the DC energy consumption device when a fault occurs in the receiving-end AC system when the surplus power of the system is 100 MW according to an embodiment of the present invention.

Detailed ways

In order to make those skilled in the art better understand the technical solutions of the present invention, the present invention is described in detail through specific embodiments. However, it should be understood that the specific embodiments are provided only for a better understanding of the present invention, and they should not be construed to limit the present invention. In describing the present invention, it is to be understood that the terms used are for the purpose of description only and should not be construed to indicate or imply relative importance.

In view of the frequent occurrence of switching peaks in the DC energy consumption device in the prior art, the DC voltage control effect is greatly reduced, and the related electrical equipment is frequently subjected to impact, the present invention proposes a grouped centralized DC energy consumption that optimizes DC voltage control The device, the control method and the readable medium effectively solve the problem of large DC voltage switching peaks of a centralized DC energy consumption device through an external parallel capacitor branch, and effectively reduce the centralized DC power consumption by adopting a grouping arrangement structure and a grouping control strategy The steady-state fluctuation range of the DC voltage during the operation of the energy device significantly optimizes the DC voltage control effect of the centralized DC energy consumption device. The solution of the present invention will be described in detail below with reference to the accompanying drawings through embodiments.

Example 1

As shown in FIG. 1 , this embodiment discloses a grouped centralized DC energy consumption device for optimizing DC voltage control. The centralized DC energy consumption device is connected between the positive and negative electrodes of the DC, and includes two symmetrical groups, upper and lower. Namely the upper group and the lower group, the upper and lower groups both include resistors and a number of energy-consuming modules. In Figure 1, the energy-consuming modules in the upper and lower groups are n, which are represented as SM1, SM2, ... SMn, and each energy-consuming module In series, and in series with the resistor, and the upper and lower two groups are connected in parallel with a capacitor, respectively, and grounded through the connection between the upper and lower two groups. The energy consumption module includes a P-type field effect transistor and a diode connected in reverse parallel with it.

变为R，因此其端间电压突降，使直流电压呈现一个向下的投入尖峰；在耗能电阻切出瞬间，耗能支路电流仍然为耗能电流，但耗能支路等效电阻已从R变为

，因此其端间电压突增，使直流电压呈现一个向上的切出尖峰。In the prior art, the centralized DC energy consumption device does not include parallel capacitors. Since the current of the reactors connected on both sides of the energy consumption branch cannot be abruptly changed, the current of the energy consumption branch cannot be changed suddenly. At the moment when the energy-dissipating resistor is put into use, the current of the energy-dissipating branch is still 0, but the equivalent resistance of the energy-dissipating branch has changed from

becomes R, so the voltage between its terminals suddenly drops, causing the DC voltage to present a downward input peak; at the moment when the energy dissipation resistor is cut out, the current of the energy dissipation branch is still the energy dissipation current, but the equivalent resistance of the energy dissipation branch changed from R to

, so the voltage between its terminals suddenly increases, causing the DC voltage to present an upward cut-out peak.

变为R，其端间电压也不会突降，而是将在并联电容的稳压作用下瞬时维持不变，从而抑制直流电压投入尖峰；在耗能电阻切出瞬间，盈余功率为并联电容充电，使耗能电阻支路电流瞬变为0，即使耗能支路等效电阻从R变为

，其端间电压也不会突增，而是将在并联电容的稳压作用下瞬时维持不变，从而抑制直流电压切出尖峰。For the centralized DC energy dissipation device with the external parallel capacitor branch in this embodiment, although the current in the inductive branch on both sides cannot be changed suddenly, the parallel capacitor branch current can be changed by charging/discharging the capacitor, so that the energy dissipation branch can be adjusted. circuit instantaneous current. At the moment when the energy dissipating resistor is put on, the parallel capacitor discharges to the energy dissipating resistor, so that the branch current of the energy dissipating resistor is no longer maintained at 0, even if the equivalent resistance of the energy dissipating branch decreases from

When it becomes R, the voltage between the terminals will not drop suddenly, but will remain unchanged instantaneously under the voltage regulation of the parallel capacitor, thereby suppressing the input peak of the DC voltage; at the moment when the energy dissipation resistor is cut out, the surplus power is the parallel capacitor. Charge, so that the current of the energy dissipation branch becomes 0 instantaneously, even if the equivalent resistance of the energy dissipation branch changes from R to

, the voltage between the terminals will not increase suddenly, but will remain unchanged instantaneously under the voltage regulation of the parallel capacitor, thereby inhibiting the DC voltage from cutting out the peak.

的最大值：For non-grouped centralized DC energy-consuming devices, when the energy-dissipating resistor is switched on, the power of the energy-dissipating branch is P _N , and the discharge power of the capacitor is P _N -Δ P , where Δ P represents the surplus power of the system; when the energy-dissipating resistor is cut out When , the power of the energy-consuming branch is 0, and the discharge power of the capacitor is △ P . Its steady-state DC voltage fluctuation

The maximum value of :

Among them, U is the steady-state DC voltage, C is the equivalent capacitance, and T is the unit carrier period.

的最大值为：For the grouped centralized DC energy-consuming device in this embodiment, when both groups of energy-consuming modules are put into operation, the power of the energy-consuming branch is P _N , and the discharge power of the capacitor is P _N -ΔP ; when the two groups of energy-consuming modules are fast When both are cut out, the power of the energy-consuming branch is 0, and the discharge power of the capacitor is △ P ; when one group of energy-consuming modules is put in and the other group of energy-consuming modules is quickly cut out, the power of the energy-consuming branch is 1/2 P _N , if △ P< 1/2 P _N , then the discharge power of the capacitor is 1/2 P _N -△ P ; if △ P> 1/2 P _N , then the charging power of the capacitor is △ P- 1/2 P _N , if △ P= 1/2 P _N , the capacitor has no charge and discharge power at this time. Its steady-state DC voltage fluctuation

The maximum value is:

。

.

It can be seen that the DC voltage fluctuation of the grouped centralized DC energy consumption device in this embodiment is only 1/4 of the maximum steady-state DC voltage fluctuation of the non-grouped centralized DC energy consumption device, and it can be seen that the DC voltage fluctuation is greatly reduced.

Embodiment 2

Based on the same inventive concept, this embodiment discloses a control method for a grouped centralized DC energy consumption device for optimizing DC voltage control, using any of the above grouped centralized DC energy consumption devices, as shown in FIG. 2 , including The following steps:

S1 is based on the DC voltage reference value, and generates the duty cycle a of the fast input of the energy consumption mode through proportional integral control; FIG. 3 and FIG. 4 are respectively the carrier and the duty cycle of the upper group and the lower group of centralized DC energy consumption devices in this embodiment. Schematic of the ratio. Among them, the duty cycle a is defined as the proportion of the energy dissipation resistor input time in a unit cycle. In this embodiment, the carrier is a triangular carrier, and the higher the actual value of the DC voltage, the greater the surplus power and the greater the duty cycle a.

S2 makes the carrier phase of the upper and lower groups of energy-consuming modules differ by 180° during the enabling period of the DC energy-consuming device, and the upper and lower limits of the triangular carrier are 1 and 0 respectively, and the frequency of the triangular carrier is determined according to the switching frequency of the energy-consuming module.

S3 compares the duty cycle a generated in step S1 with the upper and lower groups of triangular carriers with faster energy consumption modules, and generates a turn-on or turn-off command for the energy consumption modules. When the duty cycle a is greater than the carrier, the energy-consuming modules of all sub-modules in the corresponding group are turned on, and the energy-consuming modules are turned on quickly; when the duty cycle a is smaller than the carrier, the energy-consuming modules of all sub-modules in the corresponding group are turned off, Quickly exit the energy consumption mode.

For non-grouped centralized DC energy-consuming devices, when the energy-dissipating resistor is switched on, the power of the energy-dissipating branch is P _N , and the discharge power of the capacitor is P _N -Δ P , where Δ P represents the surplus power of the system; when the energy-dissipating resistor is cut out When , the power of the energy-consuming branch is 0, and the discharge power of the capacitor is △ P . In order to ensure the stability of the DC voltage, the average power of the energy-dissipating branch in the unit carrier period T should be equal to the system surplus power ΔP , so the input time of the energy-dissipating resistor in the unit period T is ΔP /P _N *T . Therefore, in the unit carrier period T, the discharge energy and charging energy of the capacitor are respectively:

，系统等效电容为C，则有：It can be seen that in the unit carrier cycle T, the discharge energy and charging energy of the capacitor are equal, so that the DC voltage can be maintained stable, and the maximum fluctuation range of the DC voltage can be calculated from this. Assume that the steady-state DC voltage fluctuation range is

, the equivalent capacitance of the system is C, then:

的表达式如下：Therefore, the steady state DC voltage fluctuates

The expression is as follows:

的最大值：Since 0≤△ P≤P _N , when △ P =1/2 P _N , the steady-state DC voltage fluctuation can be obtained

The maximum value of :

For grouped centralized DC energy-consuming devices, when both groups of energy-dissipating resistors are put in, the power of the energy-dissipating branch is P _N , and the discharge power of the capacitor is P _N -△ P ; when both groups of energy-dissipating resistors are cut out, the The power of the energy-consuming branch is 0, and the discharge power of the capacitor is △ P ; when one group of energy-dissipating resistors is put in and the other group of energy-dissipating resistors is cut out, the power of the energy-dissipating branch is 1/2 P _N , if △ P< 1/ 2 P _N , then the capacitor discharge power is 1/2 P _N -△ P , if △ P> 1/2 P _N , then the capacitor charging power is △ P- 1/2 P _N , if △ P= 1/ 2 P _N , the capacitor has no charge and discharge power at this time.

。Combined with the control method in this embodiment, the steady-state DC voltage fluctuation is further analyzed

.

The triangular carrier equation in the unit period [0, T] of the upper and lower groups of DC energy dissipation devices is:

As shown in Figure 3, the two intersecting moments of the carrier and the duty cycle of the above group of DC energy consumption devices are:

As shown in Figure 4, the moment when the carrier of the next group of DC energy-consuming devices intersects with the duty cycle is:

In order to ensure the stability of the DC voltage, the duty cycle a=△ P/PN _can be obtained.

。As shown in Figure 5, if 0 ≤ △ P< 1/2 P _N , then 0 ≤ a < 1/2, then there is

.

期间，均为一组耗能电阻投入、另一组耗能电阻切出，电容放电功率为1/2P _N -△P。exist

During the period, one group of energy dissipation resistors is put in, and the other group of energy dissipation resistors is cut out, and the discharge power of the capacitor is 1/2 P _N -△ P .

期间，均为两组耗能电阻同时切出，电容放电功率为△P。exist

During the period, both sets of energy dissipation resistors are cut out at the same time, and the discharge power of the capacitor is △ P .

Further considering the cyclicity of the carrier, it can be known that the continuous charging/discharging energy of the capacitor in a unit carrier cycle is:

Therefore:

Therefore, the expression for steady-state DC voltage fluctuation is as follows:

。When a=0.25,

.

，任一时刻均为一组耗能电阻投入、另一组耗能电阻切出，电容无充放电功率，因此稳态直流电压波动的理论值为0。As shown in Figure 6, if △ P= 1/2 P _N , then a=1/2, then

, at any time, one group of energy-dissipating resistors is put in, and the other group of energy-dissipating resistors is cut out, and the capacitor has no charge and discharge power, so the theoretical value of steady-state DC voltage fluctuation is 0.

。As shown in Figure 7, if 1/2 P _N < △ P ≤ P _N , then 1/2 < a≤1, then there is

.

期间，均为一组耗能电阻投入、另一组耗能电阻切出，电容充电功率为△P-1/2P _N ；exist

During the period, one set of energy-dissipating resistors is put in, and the other group of energy-dissipating resistors is cut out, and the charging power of the capacitor is △ P- 1/2 P _N ;

期间，均为两组耗能电阻同时投入，电容放电功率为P _N -△P。exist

During the period, both sets of energy dissipation resistors are put into use at the same time, and the discharge power of the capacitor is P _N -△ P .

Further considering the cyclicity of the carrier, it can be known that the continuous charging/discharging energy of the capacitor in a unit carrier cycle is:

Therefore:

Therefore, the expression for steady-state DC voltage fluctuation is as follows:

。When a=0.75,

.

Therefore, the maximum steady-state DC voltage fluctuation of the grouped centralized DC energy consumption device is:

，

,

It is only 1/4 of the maximum steady-state DC voltage fluctuation of the non-grouped centralized DC energy consumption device, and it can be seen that the DC voltage fluctuation is greatly reduced.

Embodiment 3

In order to further verify the validity and feasibility of the solution of the present invention, the devices and methods in the first and second embodiments are verified through a specific embodiment.

A model of the offshore wind power flexible DC transmission system with a rated DC voltage of ±400kV and a rated capacity of 1100MW is built in PSCAD software, and the grouped centralized DC energy consumption device in Example 1 is configured. The enabling criterion of the DC energy consumption device is set as The DC voltage exceeds 1.1pu, the exit criterion is that the DC voltage is lower than 0.97pu, and the DC voltage reference value is 1.02pu, which are respectively used to verify the DC voltage control effect of the grouped centralized DC energy consumption device.

Figure 8, Figure 9 and Figure 10 are respectively the DC voltage waveforms during the operation of the DC energy consuming device when the receiver AC system failure occurs when the system surplus power is 1100MW, 550MV and 100MV in this embodiment. As shown in Figure 8-10, when the receiving end AC grid fault occurs under different system surplus power, the DC energy consumption device can quickly stabilize the DC voltage near the reference value, there is no DC voltage switching peak at the moment of switching, and The steady-state fluctuation range of the DC voltage is small, and it has a good DC voltage control effect.

This embodiment shows that the grouped centralized DC energy consumption device in the first embodiment can effectively solve the problem of large DC voltage switching peaks of the centralized DC energy consumption device through the external parallel capacitor branch. The control strategy effectively reduces the steady-state fluctuation range of DC voltage during the operation of the centralized DC energy consumption device, thereby significantly optimizing the DC voltage control effect of the centralized DC energy consumption device, and has great practical value and broadness in the field of offshore wind power transmission via flexible DC application prospects.

Embodiment 3

Based on the same inventive concept, this embodiment discloses a computer-readable storage medium, where a computer program is stored on the computer-readable storage medium, and the computer program is executed by a processor to implement any one of the above-mentioned optimized DC voltage control grouping and concentration A control method for a DC energy consumption device.

As will be appreciated by those skilled in the art, the embodiments of the present application may be provided as a method, a system, or a computer program product. Accordingly, the present application may take the form of an entirely hardware embodiment, an entirely software embodiment, or an embodiment combining software and hardware aspects. Furthermore, the present application may take the form of a computer program product embodied on one or more computer-usable storage media (including, but not limited to, disk storage, CD-ROM, optical storage, etc.) having computer-usable program code embodied therein.

The present application is described with reference to flowchart illustrations and/or block diagrams of methods, apparatus (systems), and computer program products according to embodiments of the present application. It will be understood that each flow and/or block in the flowcharts and/or block diagrams, and combinations of flows and/or blocks in the flowcharts and/or block diagrams, can be implemented by computer program instructions. These computer program instructions may be provided to the processor of a general purpose computer, special purpose computer, embedded processor or other programmable data processing device to produce a machine such that the instructions executed by the processor of the computer or other programmable data processing device produce Means for implementing the functions specified in one or more of the flowcharts and/or one or more blocks of the block diagrams.

These computer program instructions may also be stored in a computer-readable memory capable of directing a computer or other programmable data processing apparatus to function in a particular manner, such that the instructions stored in the computer-readable memory result in an article of manufacture comprising instruction means, the instructions An apparatus implements the functions specified in a flow or flows of the flowcharts and/or a block or blocks of the block diagrams.

These computer program instructions can also be loaded on a computer or other programmable data processing device to cause a series of operational steps to be performed on the computer or other programmable device to produce a computer-implemented process such that The instructions provide steps for implementing the functions specified in one or more of the flowcharts and/or one or more blocks of the block diagrams.

Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention rather than to limit them. Although the present invention has been described in detail with reference to the above embodiments, those of ordinary skill in the art should understand that: the present invention can still be Modifications or equivalent replacements are made to the specific embodiments of the present invention, and any modifications or equivalent replacements that do not depart from the spirit and scope of the present invention shall be included within the protection scope of the claims of the present invention. The above contents are only specific embodiments of the present application, but the protection scope of the present application is not limited thereto. Any person skilled in the art who is familiar with the technical scope disclosed in the present application can easily think of changes or replacements, which should cover within the scope of protection of this application. Therefore, the protection scope of the present application shall be subject to the protection scope of the claims.

Claims (10)

1. A grouping centralized direct current energy consumption device for optimizing direct current voltage control is characterized in that the centralized direct current energy consumption device is connected between a direct current positive electrode and a direct current negative electrode and comprises an upper group and a lower group which are symmetrical, the upper group and the lower group both comprise a resistor and a plurality of energy consumption modules, the energy consumption modules are connected in series and are connected with the resistor in series, the upper group and the lower group are respectively connected with a capacitor in parallel, and the upper group and the lower group are grounded through the connection positions of the upper group and the lower group.

2. The device of claim 1, wherein the energy dissipation module comprises a PFET and a diode connected in anti-parallel therewith.

3. The grouped and centralized dc energy dissipation device for optimizing dc voltage control according to claim 2, wherein the capacitors are connected in parallel to discharge the capacitors to the energy dissipation modules at the moment the energy dissipation modules are turned on, so as to suppress dc voltage input spikes; and at the moment when the energy consumption module is switched out, surplus power charges the parallel capacitor, so that the peak is restrained from being switched out by the direct-current voltage.

4. The grouped and centralized dc energy dissipation device for optimizing dc voltage control as claimed in claim 3, wherein when both sets of energy dissipation modules are turned on, the branch energy dissipation means has a power ofP _N The discharge power of the capacitor isP _N -△P(ii) a When two sets of energy consuming modules are cut off, the power of the energy consuming branch circuit is 0, and the discharge power of the capacitor is deltaP(ii) a When one set of energy consumption module is put into and the other set of energy consumption module is cut out quickly, the power of the energy consumption branch is 1/2P _N If ΔP<1/2P _N The capacitor discharge power at this time is 1/2P _N -△PIf ΔP>1/2P _N Then the capacitor charging power is ΔP-1/2P _N If ΔP=1/2P _N The capacitor has no charge and discharge power at this time.

5. The grouped concentrated dc energy consumption device for optimizing dc voltage control according to claim 4, wherein the maximum value of the steady-state dc voltage fluctuation of the grouped concentrated dc energy consumption device is:

wherein, U is a steady-state direct-current voltage, C is an equivalent capacitance, and T is a unit carrier period.

6. A method for controlling a group centralized dc consumer for optimizing dc voltage control, wherein the group centralized dc consumer of any one of claims 1 to 5 is used, and the method comprises the following steps:

generating a duty ratio a of the energy consumption module fast input through proportional integral control based on the direct-current voltage reference value;

in the enabling period of the direct current energy consumption device, the phase difference of the carriers of the upper and lower groups of energy consumption modules is 180 degrees;

and comparing the duty ratio a with the carriers of the upper and lower groups of energy consumption modules to generate a switching-on or switching-off instruction of the energy consumption module.

7. The method for controlling a grouped centralized direct-current energy consumption device according to claim 6, wherein when the duty ratio a is greater than the carrier, the energy consumption modules of all the sub-modules in the corresponding group are turned on, and the energy consumption modules are put into operation; and when the duty ratio a is smaller than the carrier wave, the energy consumption modules of all the sub-modules in the corresponding group are turned off, so that the energy consumption modules are quickly exited.

8. The method for controlling a grouped and centralized dc consumer according to claim 6, wherein the higher the actual value of the dc voltage, the larger the duty cycle a.

9. The method as claimed in claim 6, wherein the carrier is a triangular carrier, the upper and lower limits of the triangular carrier are 1 and 0, respectively, and the frequency of the triangular carrier is determined according to the switching frequency of the energy consumption module.

10. A computer-readable storage medium, characterized in that a computer program is stored on the computer-readable storage medium, which computer program is executable by a processor to implement the method for controlling an optimized dc voltage controlled, grouped, centralized dc consumer according to any of the claims 6-9.

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