CN115051344A

CN115051344A - Independent power limiting direct-current load control equipment and direct-current micro-grid

Info

Publication number: CN115051344A
Application number: CN202210808050.7A
Authority: CN
Inventors: 李运; 魏学良; 余蜜; 朱国荣
Original assignee: Wuhan Zhongwei High Tech New Energy Co ltd
Current assignee: Wuhan Zhongwei High Tech New Energy Co ltd
Priority date: 2022-07-11
Filing date: 2022-07-11
Publication date: 2022-09-13

Abstract

This paper relates to little electric wire netting field, provides a autonomic limit power direct current load control equipment and direct current little electric wire netting, and autonomic limit power direct current load control equipment includes: a converter, first and second voltage detection devices, a power control device; the converter is used for supplying power to the load according to the control signal of the power control device; the first voltage detection device is used for detecting the voltage of the direct current bus; the second voltage detection device is used for detecting the output voltage; the power control equipment is used for determining a target load power limit value according to the direct-current bus voltage and a preset relation curve between the load power limit value and the voltage, determining a target current according to the load demand information, the output voltage and the target load power limit value, and sending a control signal to the converter according to the target current. The power limit value of the load can be adjusted in real time according to the voltage of the direct current bus, so that the condition that the direct current load is too heavy when the direct current bus is connected into the direct current micro-grid, the direct current bus falls out in an over-range mode, and damage is caused to the direct current micro-grid and the direct current load is avoided.

Description

Independent power limiting direct current load control equipment and direct current microgrid

Technical Field

The invention relates to the field of micro-grids, in particular to an autonomous power-limiting direct-current load control device and a direct-current micro-grid.

Background

With the shortage of energy, electric vehicles are rapidly developed, and electric vehicle charging station networks are also rapidly developed. With the rapid increase of the distribution range and the number of charging devices (branch loads), the current charging devices get larger and larger electric power from a direct current power grid. In the prior art, when the charging device gets power from the dc power grid, only self required power is considered, and the load carrying capacity of the dc power grid is not considered, so that when the load of the dc micro-power grid is too heavy, the dc bus falls out beyond the range, and damages are caused to the dc micro-power grid and the dc load.

Disclosure of Invention

The direct current bus dropping method is used for solving the problems that in the prior art, direct current loads acquire electric quantity from a direct current micro-grid according to self requirements, when the direct current micro-grid is overloaded, a direct current bus drops in an over-range mode, and damage is caused to the direct current micro-grid and the direct current loads.

In order to solve the above technical problem, an aspect of the present disclosure is to provide an autonomous limited power dc load control device, including: the power control device comprises a converter, a first voltage detection device, a second voltage detection device and a power control device;

the input end of the converter is connected with a direct current bus, the output end of the converter is connected with a load, and the control end of the converter is connected with the output end of the power control equipment and used for supplying power to the load according to the control signal of the power control equipment;

the first voltage detection equipment is connected with the direct current bus and used for detecting the voltage of the direct current bus;

the second voltage detection device is connected with the output end of the converter and used for detecting output voltage;

the input end of the power control device is connected with the first voltage detection device and the second voltage detection device, and is used for determining a target load power limit value according to a direct-current bus voltage and a preset relation curve between the load power limit value and the voltage, determining a target current according to load demand information, an output voltage and the target load power limit value, and generating and sending a control signal to the converter according to the target current;

the relation curve of the load power limit value and the voltage meets the following conditions: when the voltage of the direct current bus is smaller than the lowest voltage of the load, the limit value of the load power is zero; when the direct current bus voltage is in the range of the lowest load voltage and the start voltage of the load limiting power, the load power limiting value and the direct current bus voltage are in a monotonous non-decreasing relation.

As a further embodiment herein, the monotonically non-decreasing relationship comprises at least one of the following relationships: linear incremental relationship, stepwise jump incremental relationship, and direct proportional function relationship.

In a further embodiment herein, the determining, by the power control apparatus, the target load power limit from the dc bus voltage and a preconfigured load power limit versus voltage relationship comprises:

acquiring a load power limit value corresponding to the direct-current bus voltage according to a relation or a relation table of a preset relation curve of the load power limit value and the voltage;

and taking the acquired load power limit value as a target load power limit value.

As a further embodiment herein, the load demand information is load demand power, and the power control apparatus includes: the device comprises a first matching module, a first comparison module, a first calculation module and a first current control module;

the first matching module is connected with the first voltage detection device and used for determining a target load power limit value according to the direct-current bus voltage and a pre-configured relation curve between the load power limit value and the voltage;

the first comparison module is connected with the first matching module and is used for comparing the load demand power with a target load power limit value and screening out the smaller one as target power;

the first calculation module is connected with the first comparison module and the second voltage detection device and used for calculating to obtain a target current according to a target power and an output voltage;

the first current control module is connected with the first calculation module and used for generating a control signal according to the target current.

As a further embodiment herein, the load demand information is a load demand current, the power control apparatus comprising: the device comprises a second matching module, a second calculating module, a second comparing module and a second current control module;

the second matching module is connected with the first voltage detection device and used for determining a target load power limit value according to the direct-current bus voltage and a pre-configured relation curve between the load power limit value and the voltage;

the second calculation module is connected with the second matching module and the second voltage detection device and used for calculating a target current limit value according to the output voltage and a target load power limit value;

the second comparison module is connected with the second calculation module and is used for comparing a target current limit value with the load demand current and screening out a small value as the target current, wherein the load demand current corresponds to the load demand power;

the second current control module is connected with the second comparison module and used for generating a control signal according to the target current.

As a further embodiment herein, the control apparatus further comprises: a voltage control module;

the voltage control module is connected with the second voltage detection device and the second comparison module, and determines the current required by the load according to the output voltage.

As a further embodiment herein, the autonomous power limited dc load control device further comprises: a DC load switch assembly; wherein, the direct current load switch subassembly includes: the device comprises a voltage detection module, a current detection module, a power calculation module, a control module and a controlled switch;

the voltage detection module is connected with the direct current bus and used for detecting the voltage of the direct current bus;

the current detection module is connected with the direct current bus and used for detecting the current of the direct current bus;

the power calculation module is connected with the voltage detection module and the current detection module and used for calculating power to be detected according to the direct current bus current and the direct current bus voltage;

the control module is connected with the power control equipment and a controlled switch, the controlled switch is connected between the automatic power limiting direct current load control equipment and the direct current bus, and the control module is used for judging whether the power to be detected is within a target load power limiting range or not, disconnecting the controlled switch if the power to be detected is not within the target load power limiting range, and keeping the controlled switch off if the power to be detected is not within the target load power limiting range.

As a further embodiment herein, the power detection device is replaced with a current detection device;

replacing a pre-configured relation curve of the load power limit value and the voltage by a pre-configured relation curve of the load current limit value and the voltage;

the target load power limit is replaced with the target load current limit.

Another aspect of this document provides a dc microgrid comprising a plurality of autonomous power-limiting dc load control devices as described in any of the preceding embodiments, and a plurality of loads, each autonomous power-limiting dc load control device being connected between each load and a dc bus.

In a further embodiment, the load power limit value and the voltage relation curve of the configuration of each main power limit direct current load control device are different;

load limiting power starting voltage V of relation curve of load power limiting value and voltage _Lmini1 The lower the power supply priority of the corresponding direct current load is.

The autonomous power-limiting direct-current load control device provided by the invention is used for supplying power to a direct-current load, detecting the voltage of a direct-current bus and the output voltage of the device in real time, determining a target load power limit value according to the voltage of the direct-current bus and a relation curve between the pre-configured load power limit value and the voltage, and automatically adjusting the maximum current supplied to the direct-current load according to the target power limit value, the output voltage and direct-current load demand information, so that the condition that the direct-current load connected into a direct-current microgrid is too heavy, the direct-current bus falls out in an over-range mode and the direct-current microgrid and the direct-current load are damaged is avoided.

In order to make the aforementioned and other objects, features and advantages of the present invention comprehensible, preferred embodiments accompanied with figures are described in detail below.

Drawings

In order to more clearly illustrate the embodiments or 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 only some embodiments of the present invention, and it is obvious for those skilled in the art that other drawings can be obtained according to the drawings without creative efforts.

Fig. 1 shows a block diagram of a main power limited dc load control device according to an embodiment of the present disclosure;

FIG. 2 is a schematic diagram illustrating load power limit versus voltage for embodiments herein;

FIG. 3 shows a block diagram of a power control apparatus of embodiments herein;

FIG. 4A shows another block diagram of a power control device of embodiments herein;

FIG. 4B is a block diagram of a power control apparatus according to an embodiment of the present disclosure;

FIG. 5A illustrates a block diagram of a DC load switch assembly according to embodiments herein;

FIG. 5B illustrates another block diagram of the DC load switch assembly of the embodiments herein;

fig. 6 shows a block diagram of a main power limited dc load control device according to an embodiment of the present disclosure;

FIG. 7 is a schematic diagram illustrating load current limit versus voltage for embodiments herein;

FIG. 8 illustrates a detailed schematic of a load power limit versus voltage for embodiments herein;

FIG. 9 shows a block diagram of a DC microgrid according to embodiments herein;

fig. 10 shows a block diagram of a power control device of an embodiment herein.

Description of the symbols of the drawings:

100. an autonomous power-limiting direct current load control device;

110. a converter;

120. a voltage detection device;

130. a power control device;

140. a voltage detection device;

400. a DC load switch assembly;

200. a direct current bus;

300. a load;

301. 301', a matching module;

302. 302', a comparison module;

303. 303', a calculation module;

304. 304', a current control module;

305. a voltage control module;

501. a voltage detection module;

502. a current detection module;

503. a power calculation module;

504. a control module;

505. a controlled switch;

1002. a power control device;

1004. a processor;

1006. a memory;

1008. a drive mechanism;

1010. an input/output module;

1012. an input device;

1014. an output device;

1016. a presentation device;

1018. a graphical user interface;

1020. a network interface;

1022. a communication link;

1024. a communication bus.

Detailed Description

The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments herein without making any creative effort, shall fall within the scope of protection.

It should be noted that the terms "first," "second," and the like in the description and claims herein and in the above-described drawings are used for distinguishing between similar elements and not necessarily for describing a particular sequential or chronological order. It is to be understood that the data so used is interchangeable under appropriate circumstances such that the embodiments herein described are capable of operation in sequences other than those illustrated or described herein. Furthermore, the terms "comprises," "comprising," and "having," and any variations thereof, are intended to cover a non-exclusive inclusion, such that a process, method, apparatus, article, or device that comprises a list of steps or elements is not necessarily limited to those steps or elements expressly listed, but may include other steps or elements not expressly listed or inherent to such process, method, article, or device.

In an embodiment of the present disclosure, an autonomous power-limiting dc load control device is provided, so as to solve a problem in the prior art that a dc load obtains power from a dc microgrid according to its own requirement, and when the dc microgrid load is too heavy, a dc bus falls out beyond a range, thereby causing damage to the dc microgrid and the dc load.

Specifically, as shown in fig. 1, the autonomous limited power dc load control device 100 includes: converter 110, voltage detection device 120, power control device 130, voltage detection device 140.

The input end of the converter 110 is connected to the dc bus 200, the output end of the converter 110 is connected to the dc load 300, and the control end of the converter 110 is connected to the output end of the power control device 130, for supplying power to the load 300 according to the control signal of the power control device 130.

The input terminal of the voltage detection device 120 is connected to the dc bus 200 for detecting the dc bus voltage.

The voltage detection device 140 is connected to the output of the converter 110 for detecting the output voltage of the converter.

The input end of the power control device 130 is connected to the voltage detection device 120 and the voltage detection device 140, and is configured to determine a target load power limit according to the dc bus voltage and a pre-configured relationship curve between the load power limit and the voltage, determine a target current according to the load demand information, the output voltage, and the target load power limit, and generate and send a control signal to the converter 110 according to the target current.

The relation curve of the load power limit value and the voltage meets the following conditions: when the voltage of the direct current bus is smaller than the lowest voltage of the load, the limit value of the load power is zero; when the direct current bus voltage is in the range of the lowest load voltage and the start voltage of the load limiting power, the load power limiting value and the direct current bus voltage are in a monotonous non-decreasing relation. The monotonic non-decreasing relationship includes at least one of: linear incremental relationship, stepwise jump incremental relationship, and direct proportional function relationship. When the voltage of the direct current bus is greater than or equal to the starting voltage of the load limiting power, the load power (current) is set according to the load requirement, and at the moment, the load power limiting value can be set as the load rated power.

Specifically, in this document, the load power is set to be positive, and the generated power is set to be negative.

The load demand information may be a load demand current and may also be a load demand power, and the load demand current may be multiplied by the output voltage to obtain the load demand power. The load demand information can be configured in the power control device by a user according to the load demand condition, if the load and the autonomous power-limiting direct current load control device have the communication function, the load demand information can also be sent to the autonomous power-limiting direct current load control device by the load, for example, the load is an electric vehicle, and the autonomous power-limiting direct current load control device can communicate with a battery management system of the electric vehicle, so as to obtain the load demand information.

The dc bus described herein is also connected to a dc power supply (a dc power supply from ac to dc, a dc power supply from dc to dc) for providing electric energy to the dc bus. The converter 110 includes a dc-dc converter and a dc-ac converter. The inverter 110 can convert the dc power on the dc bus to the dc or ac power required by the load to power the load. In the specific implementation, the converter is a conventional converter, and the specific model, manufacturer and the like of the converter are not limited herein. The load described herein includes a rechargeable battery, a charging pile, and the like.

The

voltage detection devices

120 and 140 are conventional voltage devices, and are not limited herein.

The power control device 130 at least includes a memory in which a pre-configured relationship curve between a load power limit and a voltage is stored, and a processor for generating a control signal. In implementation, the power control device 130 may rapidly complete the relationship curve configuration through the relationship parameter of the relationship curve in the local setting, and may further add a communication module, through which communication with the remote device may be implemented, and the remote device sends the configuration information of the relationship curve between the load power limit and the voltage to the power control device 130. The relation curve of the load power limit value and the voltage is expressed by a relation or a relation table, and the following configuration information can be referred to: the load minimum voltage, the load limiting power starting voltage, the load rated power, the limit value curve and the like. The load minimum voltage, the load-limiting power starting voltage and the load limiting power in the relation curve of the load power limiting value and the voltage are configured by operation and maintenance personnel, and specific values of the load minimum voltage, the load-limiting power starting voltage and the load limiting power are not limited in the text.

In one embodiment, as shown in fig. 2, the load power limit versus voltage curve includes:

(1) when the DC bus voltage V _dc Satisfy V _dc >V _Lmini1 The limit value of the load power is the rated power P of the load equipment _r 。

(2) When the DC bus voltage V _dc Satisfy V _Lmini1 ≥V _dc ≥V _Lmini2 When the load is in a power-limiting state, the direct current bus voltage and the load power limit value are in a monotonous non-decreasing relation. In order to improve the power limiting precision, when the direct current bus voltage V _dc Satisfy V _Lmini1 ≥V _dc ≥V _Lmini2 And may include a multi-segment monotonically non-decreasing relationship.

(3) When the DC bus voltage V _dc Satisfy V _dc <V _Lmini2 The load power limit is zero.

Wherein, V in the curve relation _r At rated voltage, V _Lmini1 Is a load-limiting power starting voltage which is less than the limited absorption power starting voltage of a direct current power supply in a direct current micro-grid _Lmini2 The load minimum voltage is greater than the DC minimum voltage of the DC power supply in the DC micro-grid.

In this embodiment, the autonomous power-limiting dc load control device also detects the dc bus voltage and the output voltage of the device in real time while supplying power to the dc load, determines the target load power limit according to the dc bus voltage and the relationship curve between the pre-configured load power limit and the voltage, and automatically adjusts the maximum current supplied to the dc load according to the target power limit, the output voltage, and the dc load demand information, thereby preventing the dc load connected to the dc microgrid from being too heavy, which further causes the dc bus to fall out of the range, and causes damage to the dc microgrid and the dc load.

Specifically, whether the equipment enters an autonomous power limit operation interval or not is determined according to a relation curve of a preset load power limit value and voltage by acquiring a voltage value of a direct-current bus. Acquiring the load state information of the direct-current microgrid through the voltage value of the direct-current bus, wherein the load is under a heavy load (the voltage of the direct-current bus is lower than a load power limit value V) _Lmini1 ) And when the load power limit value is reduced, the load power limit value is automatically reduced according to a relation curve of the pre-configured load power limit value and the voltage, so that the absorbed power of the slave direct current bus is reduced, and the stable operation of the power flow is cooperatively maintained. When the load is reduced (when the DC bus voltage is increased)) And automatically increasing the load power limit according to a relation curve of the pre-configured load power limit and voltage, so as to increase the absorbed power range of the direct current bus or convert the absorbed power range into power supply according to the load requirement. The whole process synergistically maintains the balance and stable operation of the current micro-grid tide, and prevents the undervoltage or unstable operation of the direct current bus of the direct current micro-grid caused by the overweight of the load. The whole cooperation process only needs to detect the voltage of the public direct current bus, does not need extra rapid communication hardware, and has the advantages of simple realization and high regulation efficiency.

In an embodiment of this document, the determining, by the power control device, the target load power limit according to the dc bus voltage and a preconfigured relationship curve between the load power limit and the voltage includes:

acquiring a load power limit value corresponding to the direct-current bus voltage according to a relation or a relation table of a preset relation curve of the load power limit value and the voltage; and taking the acquired load power limit value as a target load power limit value.

In an embodiment of this document, the load demand information is a load demand power (the load demand power may be directly sent to the autonomous power-limiting dc load control device by a load, or a load demand current and a load demand voltage are sent to the autonomous power-limiting dc load control device, and the load demand power is calculated by the autonomous power-limiting dc load control device according to the load demand current and the load demand voltage), and correspondingly, as shown in fig. 3, the power control device includes: a matching module 301, a comparison module 302, a calculation module 303 and a current control module 304.

The matching module 301 is connected to the voltage detection device 120, and configured to determine a target load power limit P according to the dc bus voltage vin and a pre-configured relationship curve between the load power limit and the voltage _limit 。

The comparison module 302 is connected to the matching module 301 for comparing the load demand power P _oref And target load power limit P _limit The smaller is selected as the target power P _or . Specifically, the comparison module 302 implements the functions of the following formulas: p _ldc1 ＝min(P _ldc1r ,P _limit ) Wherein P is _limit To target load powerLimit value, P _ldc1r Demand power for the load, P _ldc1 Is the target power.

The calculation module 303 is connected to the comparison module and the voltage detection device 140, and is used for calculating the target power P _or And an output voltage v _o Calculating to obtain a target current i _or 。

The current control module 304 is connected to the calculation module 303, and is configured to generate a control signal according to the target current.

In an embodiment of this document, the load demand information is a load demand current, and when the input power source connected to the dc bus is a current source type, as shown in fig. 4A, the power control device 130 includes: matching module 301 ', calculation module 303', comparison module 302 ', current control module 304'.

The matching module 301' is connected to the voltage detection device 120 for determining the voltage v of the dc bus _in And determining a target load power limit value P according to a preset relation curve of the load power limit value and the voltage _limit 。

The calculating module 303 'is connected to the matching module 301' and the voltage detecting device 140, and is used for calculating the power limit value P according to the output voltage vo and the target load power _limit Calculating a target current limit i _limit . Specifically, the target current limit is obtained by dividing the target load power limit by the input voltage of the load.

The comparison module 302 'is connected with the calculation module 303' and is used for comparing the target current limit value i _limit And load demand current i _oref And the target current i with a small value is selected from the current values _or Wherein the load demand current corresponds to the load demand power.

The current control module 304 'is connected to the comparison module 302' for generating a control signal according to the target current and sending it to the converter 110.

In an embodiment of this document, when the input power source connected to the dc bus is a voltage source type, as shown in fig. 4B, the power control device 130 includes, in addition to the matching module 301 ', the calculating module 303', the comparing module 302 ', and the current control module 304': a voltage control module 305. Voltage control module 305 interface voltage detectionThe device 140 and the comparison module 302' according to the output voltage v _o And load demand voltage v _oref Determining the load demand current i _oref 。

The current control module described herein may be configured with a PI control strategy for causing the output current i _o Approaching to target current i wirelessly _or 。

The power control apparatus shown in fig. 3 to 4B can improve the efficiency of the power limit value by controlling by the amount of current directly detected.

In an embodiment herein, as shown in fig. 5A, the autonomous limited power dc load control device further includes: direct current load switch subassembly. Wherein, direct current load switch subassembly includes: a voltage detection module 501, a current detection module 502, a power calculation module 503, a control module 504 and a controlled switch 505.

The voltage detection module 501 is connected to the dc bus 200 and configured to detect a dc bus voltage.

The current detection module 502 is connected to the dc bus and configured to detect a current of the dc bus.

The power calculating module 503 is connected to the voltage detecting module 501 and the current detecting module 502, and is configured to calculate the power to be detected according to the dc bus current and the dc bus voltage. The power calculation module 503 is a multiplier, and is configured to perform product processing on the dc bus current and the dc bus voltage, where the product value is the power to be detected.

The control module 504 is connected to the power control device 130 and the controlled switch 505, the controlled switch 505 is connected between the autonomous power limiting dc load control device and the dc bus, and the control module 504 is configured to determine whether the power to be detected is within a target load power limit range, that is, whether the power to be detected is smaller than an upper limit value of the target load power limit range and larger than a lower limit value of the target load power limit range, if not, the controlled switch 505 is turned off, and if so, the controlled switch 505 is kept turned off.

The voltage detection module 501 and the current detection module 502 may be implemented by voltage and current detection devices available in the market, and the specific manufacturer structure is not limited herein.

When the controlled switch 505 is turned off because the power to be detected exceeds the upper limit value of the target load power limit range, it is necessary to wait for the remote control command or the local command to be turned back on. When the controlled switch 505 is disconnected because the power to be detected is smaller than the lower limit value of the target load power limit value range, and the voltage of the direct current bus rises to be not lower than the output power overrun voltage recovery value, the controlled switch 505 is automatically closed or is restored to be closed through a remote control command or a local command.

In this embodiment, by setting the dc load switch component, it can be monitored whether the autonomous power limiting dc load control device operates within the power limiting range allowed by the dc microgrid, and if the autonomous power limiting dc load control device operates beyond the power limiting range, the branch is quickly disconnected, and the dc microgrid tidal current is cooperatively controlled to operate stably.

In an embodiment of the present disclosure, since the power and the current are in a direct proportion relationship, as shown in fig. 6, the current detection device may be used to replace the power detection device to obtain a simplified version of the autonomous power-limiting dc load control device, and a preconfigured load current limit versus voltage relationship curve (as shown in fig. 7) is used to replace the preconfigured load power limit versus voltage relationship curve. The target load power limit is replaced with the target load current limit. The power control device is used for determining a target current according to the load demand current and the target load current limit value and sending a control signal to the converter according to the target current.

As shown in fig. 5B, the dc load switch module connected in this embodiment omits the voltage detection module and the power calculation module, and includes: a current detection module 502, a control module 504 and a controlled switch 505.

The control module 504 is connected to the power control device 130, and is configured to determine whether the dc bus current is within a target load current limit range, that is, whether the dc bus current is smaller than an upper limit value of the target load current limit range and larger than a lower limit value of the target load current limit range, if not, turn off the controlled switch 505, and if so, keep the controlled switch 505 turned off.

In the direct-current micro-grid, the allowed operation power (current) interval of the autonomous power-limiting direct-current load control device is not larger than the allowed operation power (current) interval of the direct-current load switch assembly.

In order to make the objects, technical solutions and advantages of the present invention more apparent, the following description is given with reference to a specific example. As shown in fig. 8, in this example, the load is a dc charging device, and its rated power is 100kW, and the rated voltage of the dc bus is 750V. Load power limit V _Lmini1 740V, the lowest voltage V of the load _Lmini2 Is 720V.

When the DC bus voltage is lower than 720V (V) _Lmini2 ) At times, the dc charging device disables power from being drawn from the dc bus.

When the DC bus voltage is (720V, 740V) (V) _Lmini2 ，V _Lmini1 ) In the interval, the direct current charging equipment is in an autonomous power limiting interval, when the required power of the equipment is larger than a power limit value, the energy is absorbed from the direct current bus according to the power limit value to supply power to the direct current charging equipment, and when the required power of the equipment is smaller than or equal to the power limit value, the energy is absorbed from the direct current bus according to the required power of the direct current charging equipment to supply power to the direct current charging equipment.

When the DC bus voltage is larger than 740V (V) _Lmini1 ) And in the process, energy is absorbed from the direct current bus according to the power required by the direct current charging equipment to supply power to the direct current charging equipment (namely, the direct current charging equipment operates at unlimited power).

Specifically, a mathematical relation expression of a relation curve between the load power limit value and the voltage shown in fig. 8 is as formula (1), and a power operation interval of the dc charging device is as formula (2).

When the DC bus voltage is greater than 740V, the power limit value obtained by the equation (1) is 100kW of rated capacity, as shown in FIG. 4A or FIG. 4Bi _oref Less than or equal to power limit value P of relation curve of load power limit value and voltage _limit Calculated current limit i _limit The target current i finally supplied to the current control module after the minimum value is obtained _or Load demand current i output for voltage control module _oref The characteristic that the energy is absorbed from the direct current bus to supply power to the load according to the power required by the load is realized.

When the DC bus voltage is in the interval of (720V, 740V), the power limit P can be obtained by the formula (1) _limit If i in FIG. 4A or FIG. 4B _oref Less than or equal to the power limit value P _limit Calculated current limit i _limit The target current i finally supplied to the current control module after the minimum value is obtained _or Load demand current i output for voltage control module _oref Namely, the characteristic of absorbing energy from the direct current bus to supply power to the load according to the power required by the load. If i in FIG. 4A or FIG. 4B _oref Greater than power limit P _limit Calculated current limit i _limit The target current i finally supplied to the current control module after the minimum value is obtained _or Is a current limit value i _limit I.e. absorb energy from the dc bus to power the load at the power limit.

When the DC bus voltage is less than 720V, the power limit value obtained by the formula (1) is 0, and the current limit value i _limit Is 0, i in FIG. 4A or 4B _oref More than or equal to 0, and finally supplying the target current i to the current control module after the minimum value is obtained _or Is 0, i.e. the power supply to the load is stopped.

In an embodiment of this document, there is also provided a dc microgrid, as shown in fig. 9, the dc microgrid includes at least: the autonomous limited power dc load control apparatus 100 and the plurality of loads 300 according to any of the above embodiments. The dc load switch assembly 400 according to the previous embodiment may be further disposed between the connection lines of the loads 300 and the dc bus 200.

When a plurality of autonomous power-limiting direct-current load control devices are simultaneously connected to a direct-current microgrid, the power supply priority of the direct-current load can be set by setting different relation curves of the load power limiting values and the voltage. When limit load powerStarting voltage V _Lmini1 The lower the load power supply power is, the larger the corresponding load power supply power unlimited area is, and the higher the priority of the load power supply is. Otherwise, the lower the priority of the load power supply.

In an embodiment herein, a power control apparatus is shown in fig. 10, and includes: the controller comprises a memory 1006 and a processor 1004, wherein the memory 1006 stores a preset relation curve between a load power limit value and a voltage, and the processor 1004 is used for generating a control signal. In detail, a processor 1004, such as one or more Central Processing Units (CPUs), in the power control device 1002 may each implement one or more hardware threads. The memory 1006 in the power control device 1002 may include any one or combination of: any type of RAM, any type of ROM, flash memory devices, hard disks, optical disks, etc. More generally, any memory may use any technology to store information. Further, any memory may provide volatile or non-volatile retention of information. Further, any memory may represent fixed or removable components of power control device 1002. In one case, when processor 1004 executes associated instructions stored in any memory or combination of memories, power control device 1002 may perform any of the operations of the associated instructions. The power control device 1002 also includes one or more drive mechanisms 1008, such as a hard disk drive mechanism, an optical disk drive mechanism, or the like, for interacting with any memory.

Power control device 1002 may also include an input/output module 1010(I/O) for receiving various inputs (via input device 1012) and for providing various outputs (via output device 1014). One particular output mechanism may include a presentation device 1016 and an associated graphical user interface 1018 (GUI). In other embodiments, input/output module 1010(I/O), input device 1012, and output device 1014 may also not be included, but merely as a power control device in the network. Power control device 1002 may also include one or more network interfaces 1020 for exchanging data with other devices via one or more communication links 1022. One or more communication buses 1024 couple the above-described components together.

Communication link 1022 may be implemented in any manner, such as over a local area network, a wide area network (e.g., the Internet), a point-to-point connection, etc., or any combination thereof. Communications link 1022 may include any combination of hardwired links, wireless links, routers, gateway functions, name servers, etc., governed by any protocol or combination of protocols.

It should be understood that, in various embodiments herein, the sequence numbers of the above-mentioned processes do not mean the execution sequence, and the execution sequence of each process should be determined by its function and inherent logic, and should not constitute any limitation to the implementation process of the embodiments herein.

Those of ordinary skill in the art will appreciate that the elements and algorithm steps of the examples described in connection with the embodiments disclosed herein may be embodied in electronic hardware, computer software, or combinations of both, and that the components and steps of the examples have been described in a functional general in the foregoing description for the purpose of illustrating clearly the interchangeability of hardware and software. Whether such functionality is implemented as hardware or software depends upon the particular application and design constraints imposed on the technical solution. Skilled artisans may implement the described functionality in varying ways for each particular application, but such implementation decisions should not be interpreted as causing a departure from the scope of the present disclosure.

It is clear to those skilled in the art that, for convenience and brevity of description, the specific working processes of the above-described systems, apparatuses and units may refer to the corresponding processes in the foregoing method embodiments, and are not described herein again.

In the several embodiments provided herein, it should be understood that the disclosed system, apparatus, and method may be implemented in other ways. For example, the above-described apparatus embodiments are merely illustrative, and for example, the division of the units is only one logical division, and other divisions may be realized in practice, for example, a plurality of units or components may be combined or integrated into another system, or some features may be omitted, or not executed. In addition, the shown or discussed mutual coupling or direct coupling or communication connection may be an indirect coupling or communication connection through some interfaces, devices or units, and may also be an electric, mechanical or other form of connection.

The units described as separate parts may or may not be physically separate, and parts displayed as units may or may not be physical units, may be located in one place, or may be distributed on a plurality of network units. Some or all of the units can be selected according to actual needs to achieve the purposes of the embodiments herein.

In addition, functional units in the embodiments herein may be integrated into one processing unit, or each unit may exist alone physically, or two or more units are integrated into one unit. The integrated unit can be realized in a form of hardware, and can also be realized in a form of a software functional unit.

The integrated unit, if implemented in the form of a software functional unit and sold or used as a stand-alone product, may be stored in a computer readable storage medium. Based on such understanding, the technical solutions in the present disclosure may be implemented in the form of a software product, which is stored in a storage medium and includes several instructions for causing a computer device (which may be a micro control unit, a digital signal processor, a personal computer, a server, or a network device) to execute all or part of the steps of the methods described in the embodiments of the present disclosure. And the aforementioned storage medium includes: a U-disk, a removable hard disk, a Read-Only Memory (ROM), a Random Access Memory (RAM), a magnetic disk or an optical disk, and other various media capable of storing program codes.

The principles and embodiments of this document are explained herein using specific examples, which are presented only to aid in understanding the methods and their core concepts; meanwhile, for a person skilled in the art, according to the idea of the present disclosure, there may be variations in the specific embodiments and application ranges, and in summary, the content of the present disclosure should not be understood as a limit value of the present disclosure.

Claims

1. An autonomous power limited dc load control device, comprising: the power control device comprises a converter, a first voltage detection device, a second voltage detection device and a power control device;

the input end of the power control device is connected with the first voltage detection device and the second voltage detection device, and is used for determining a target load power limit value according to a direct-current bus voltage and a relation curve between a pre-configured load power limit value and voltage, determining a target current according to load demand information, an output voltage and the target load power limit value, and generating and sending a control signal to the converter according to the target current;

2. The autonomous limited power dc load control device of claim 1, wherein the monotonically non-decreasing relationship comprises at least one of: linear incremental relationship, stepwise jump incremental relationship, and direct proportional function relationship.

3. The autonomous power limited dc load control device of claim 1, wherein the power control device determines the target load power limit from the dc bus voltage and a preconfigured load power limit versus voltage curve comprising:

4. The autonomous limited power dc load control device of claim 1, wherein the load demand information is a load demand power, the power control device comprising: the device comprises a first matching module, a first comparison module, a first calculation module and a first current control module;

5. The autonomous limited power dc load control device of claim 1, wherein the load demand information is a load demand current, the power control device comprising: the device comprises a second matching module, a second calculating module, a second comparing module and a second current control module;

6. The autonomous limited power dc load control device of claim 5, wherein the control device further comprises: a voltage control module;

7. The autonomous limited power dc load control device of claim 1, further comprising: a DC load switch assembly; wherein, the direct current load switch subassembly includes: the device comprises a voltage detection module, a current detection module, a power calculation module, a control module and a controlled switch;

8. The autonomous limited power dc load control device of claim 1 wherein the power sensing device is replaced with a current sensing device;

the target load power limit is replaced with the target load current limit.

9. A dc microgrid comprising a plurality of autonomous power-limited dc load control devices of any of claims 1 to 7 and a plurality of loads;

each autonomous power limited dc load control device is connected between each load and a dc bus.

10. The dc microgrid of claim 9 wherein load power limits configured by respective main power limit dc load control devices vary from voltage to voltage;

the lower the load limiting power starting voltage of the relation curve of the load power limiting value and the voltage is, the higher the corresponding load power supply priority is.