Direct current microgrid and power control method thereof

Abstract

A direct current microgrid is provided, including: a direct current bus; and a plurality of devices connected to the direct current bus, wherein at least one device of the plurality of devices is configured to: detect a voltage on the direct current bus and a power of the device; maintain the power of the device to a specific power based on the voltage on the direct current bus being within a constant power voltage interval; and adjust the power and the voltage of the device based on the voltage on the direct current bus being within a droop voltage interval, wherein the specific power is not zero.

Description

Technical Field

[0001] This disclosure relates to a DC microgrid and a power control method thereof, and more specifically, to a DC microgrid based on constant power droop and a power control method thereof. Background Technology

[0002] DC microgrids, as a highly efficient and flexible distributed energy system, have wide applications in renewable energy integration, energy storage management, and load power supply. Master-slave control is a common operating mode in DC microgrid control strategies. However, traditional master-slave control cannot automatically adjust power distribution when system power is insufficient. Specifically, when the total system power cannot meet load demand, the master control unit lacks an effective adaptive adjustment mechanism, resulting in power-intensive devices (such as high-capacity loads or energy storage devices) failing to obtain a continuous voltage reference, affecting system power quality and stability. Furthermore, traditional DC microgrids suffer from the limitation of relying on droop control. Specifically, traditional droop control achieves power distribution by adjusting voltage-current characteristics, but when power is insufficient, relying solely on droop coefficient adjustment is insufficient to achieve dynamic voltage compensation. Existing methods for secondary voltage compensation by shifting the droop curve or adjusting the droop coefficient also suffer from complex adjustment algorithms.

[0003] To this end, this disclosure proposes a DC microgrid and its power control method. By adopting constant power droop, the DC microgrid can achieve self-adjustment when the power is excessive or insufficient, thereby improving the dynamic stability and adjustment convenience of the system. Summary of the Invention

[0004] According to one aspect of an embodiment of the present invention, a DC microgrid is provided, the DC microgrid comprising: a DC bus; and a plurality of devices connected to the DC bus, wherein at least one of the plurality of devices is configured to: detect the voltage on the DC bus and the power of the device; maintain the power of the device at a specific power based on the voltage on the DC bus being within a constant power voltage range; and adjust the power and voltage of the device based on the voltage on the DC bus being within a drooping voltage range, wherein the specific power is not zero.

[0005] According to another aspect of this disclosure, a power control method for a DC microgrid is provided, the DC microgrid including a DC bus and a plurality of devices connected to the DC bus, for at least one of the plurality of devices, and the method includes: detecting a voltage on the DC bus and a power of the device; maintaining the power of the device at a specific power based on the voltage on the DC bus being within a constant power voltage range; and adjusting the power and voltage of the device based on the voltage on the DC bus being within a drooping voltage range, wherein the specific power is not zero.

[0006] According to another aspect of this disclosure, a computer-readable storage medium is provided that stores computer-executable instructions thereon, which, when executed by a processing unit, are used to implement the aforementioned method.

[0007] Other aspects, advantages, and salient features of this disclosure will become apparent to those skilled in the art from the following detailed description of various embodiments disclosed in conjunction with the accompanying drawings. Attached Figure Description

[0008] The invention will be more readily understood from the following detailed description with reference to the accompanying drawings, wherein like reference numerals designate units of the same structure, and wherein:

[0009] Figure 1 A schematic diagram of a DC microgrid according to an embodiment of the present disclosure is shown;

[0010] Figures 2A to 2C The power-voltage graphs of various devices in a DC microgrid with constant power droop applied to energy storage devices according to embodiments of the present disclosure are shown.

[0011] Figures 3A to 3C The power-voltage graphs of various devices in a DC microgrid with constant power droop applied to energy storage devices and charging piles according to embodiments of the present disclosure are shown.

[0012] Figure 4 The following diagram illustrates the power-voltage plots of various devices in a DC microgrid where constant power droop is applied to active front-end (AFE) devices according to embodiments of the present disclosure.

[0013] Figure 5 A schematic diagram illustrating constant power droop achieved by an energy storage device according to an embodiment of the present disclosure is shown; and

[0014] Figure 6 A power control method for a DC microgrid according to an embodiment of the present disclosure is shown. Detailed Implementation

[0015] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0016] Furthermore, those skilled in the art will understand that the elements in the accompanying drawings are illustrated for simplicity and may not necessarily be drawn to scale. For example, the dimensions of some elements in the drawings may be enlarged relative to other elements to aid in understanding various aspects of the embodiments. Additionally, one or more elements may have been represented by various symbols in the drawings, and the drawings may only show those specific details relevant to understanding the embodiments of this disclosure, so as not to obscure details that are readily apparent to those skilled in the art who will benefit from the description herein.

[0017] Furthermore, it should be noted that in this specification, A connected to B can mean "A is directly connected to B" or "A is connected to B via other middleware". A connected between B and C can mean "A is directly connected to both B and C" or "A is connected to both B and C via other middleware".

[0018] Figure 1 A schematic diagram of a DC microgrid according to an embodiment of the present disclosure is shown.

[0019] like Figure 1 As shown, a DC microgrid may include a DC bus, battery energy storage devices (BESS), photovoltaic (PV) devices, active front-end (AFE) devices, DC load devices, bidirectional DC power generation and consumption devices, and a microgrid controller (MGC). However, it should be understood that this disclosure is not limited thereto, and a DC microgrid may include components such as... Figure 1 Show more or fewer devices.

[0020] Energy storage devices, photovoltaic devices, AFE devices, DC load devices, and bidirectional DC power generation and consumption devices can be connected to the DC bus and power is transmitted through the DC bus. The microgrid controller can control the operation of each device in the DC microgrid and configure each device.

[0021] In some examples, photovoltaic devices can be connected to the DC bus via a DC-DC converter, and energy storage devices can also be connected to the DC bus via a DC-DC converter. DC load devices can be connected to the DC bus via a DC-DC converter and a pre-charge circuit, and bidirectional DC power generation and consumption devices can also be connected to the DC bus via a DC-DC converter and a pre-charge circuit. In some embodiments, DC load devices may include devices such as lighting equipment and air conditioning. Furthermore, DC microgrids can be connected to the grid via AFE devices.

[0022] Figures 2A-2C Power-voltage graphs of various devices in a DC microgrid with constant power droop applied to energy storage devices, according to embodiments of the present disclosure, are shown. Figure 2A The power-voltage curves of various devices in a DC microgrid are described during energy storage charging. Figure 2BThe power-voltage curves of various devices in a DC microgrid are described during energy storage backup. Figure 2C The power-voltage curves of various devices in a DC microgrid are described during energy storage charging.

[0023] like Figures 2A-2C As shown, the horizontal axis represents the power of each device in the DC microgrid, and the vertical axis represents the voltage of the DC bus. Different curves are used for different devices, and each device can adjust its own power and voltage based on the curves when the DC microgrid has excess power (DC bus voltage drops) or insufficient power (DC bus voltage rises).

[0024] refer to Figure 2A Energy storage devices can have a power-voltage curve S1, photovoltaic devices can have a power-voltage curve S2, charging pile loads can have a power-voltage curve S3, and AFE devices can have a power-voltage curve S4. From Figure 2A It can be seen that only the energy storage device is configured with constant power droop. However, this disclosure is not limited to this; any power-adjustable device in a DC microgrid can be configured with constant power droop.

[0025] In some embodiments, the energy storage device can be pre-configured with a constant power voltage range and a droop voltage range. When the voltage on the DC bus is in the constant power voltage range, the power of the energy storage device can maintain a specific power, and when the voltage on the DC bus is in the droop voltage range, the power and voltage of the energy storage device can be adjusted based on a power-voltage curve. In some embodiments, this specific power can be configured by the microgrid controller and is not zero. Furthermore, this specific power should be between the maximum charging power and the maximum discharging power of the energy storage device.

[0026] like Figure 2A As shown, energy storage devices can have constant power voltage ranges △U2 and △U4, and droop voltage ranges △U1, △U3, and △U5. It can be understood that, depending on the configured constant power voltage range, droop voltage range, and the magnitude of the specific power, the energy storage device can adjust its power and voltage by following power-voltage curves with different slopes within the droop voltage range.

[0027] In some embodiments, taking a stable state with a current bus voltage of 750V as an example, when the power in the DC microgrid is insufficient and the DC bus voltage drops, if the energy storage device determines that the DC bus voltage is still within its constant power voltage range ΔU4, the energy storage device maintains its own power, and the AFE device first increases its own power. If the power in the DC microgrid is still insufficient and the DC bus voltage drops further, the energy storage device may find that the DC bus voltage is now in its drooping voltage range ΔU5, and the energy storage device increases its own discharge power. If the power in the DC microgrid is still insufficient and the DC bus voltage drops further, but the energy storage device's power has reached its discharge power limit, the charging power of the charging pile can be limited.

[0028] In some embodiments, taking a stable state with a current bus voltage of 750V as an example, when there is excess power in the DC microgrid and the DC bus voltage rises, if the energy storage device determines that the DC bus voltage is still within its constant power voltage range ΔU4, the energy storage device maintains its own power, and the AFE device first reduces its own power. If the power in the DC microgrid is still excessive and the DC bus voltage rises further, the energy storage device may find that the DC bus voltage is now in its droop voltage range ΔU3, and the energy storage device can reduce its own discharge power. If the power in the DC microgrid is still excessive and the DC bus voltage rises further, the energy storage device may find that the DC bus voltage is now in its droop voltage range ΔU1, and the energy storage device can begin charging. If the power in the DC microgrid is still excessive and the DC bus voltage rises further, the power of the photovoltaic device can be limited.

[0029] refer to Figure 2B ,and Figure 2A Similarly, energy storage devices can have a power-voltage curve S1, photovoltaic devices can have a power-voltage curve S2, charging pile loads can have a power-voltage curve S3, and AFE devices can have a power-voltage curve S4. However, with Figure 2A The difference is that only the energy storage device is configured with a constant power droop with a specific power of zero, which means it can be fitted as a droop.

[0030] In some embodiments, taking a stable state with a current bus voltage of 750V as an example, when the power in the DC microgrid is insufficient and the DC bus voltage drops, if the energy storage device determines that the DC bus voltage is still within its constant power voltage range ΔU2, the energy storage device maintains its own power, i.e., remains in standby mode, and its own power is first increased by the AFE device. If the power in the DC microgrid is still insufficient and the DC bus voltage drops further, the energy storage device may find that the DC bus voltage is now within its drooping voltage range ΔU3, and the energy storage device begins to discharge. If the power in the DC microgrid is still insufficient and the DC bus voltage drops further, but the energy storage device's power has reached its discharge power limit, the charging power of the charging pile can be limited.

[0031] In some embodiments, taking a stable state with a current bus voltage of 750V as an example, when there is excess power in the DC microgrid and the DC bus voltage rises, if the energy storage device determines that the DC bus voltage is still within its constant power voltage range ΔU2, the energy storage device maintains its own power, i.e., remains in standby mode, and the AFE device first reduces its own power. If the power in the DC microgrid is still excessive and the DC bus voltage rises further, the energy storage device may find that the DC bus voltage is now within its droop voltage range ΔU1, and the energy storage device can begin charging. If the power in the DC microgrid is still excessive and the DC bus voltage rises further, the power of the photovoltaic equipment can be limited.

[0032] refer to Figure 2C ,and Figure 2A Similarly, energy storage devices can have a power-voltage curve S1, photovoltaic devices can have a power-voltage curve S2, charging pile loads can have a power-voltage curve S3, and AFE devices can have a power-voltage curve S4. However, with Figure 2A Unlike other energy storage devices, energy storage devices are configured to maintain a specific power level below zero within a constant power voltage range.

[0033] In some embodiments, taking a stable state with a current bus voltage of 750V as an example, when the power in the DC microgrid is insufficient and the DC bus voltage drops, if the energy storage device determines that the DC bus voltage is still within its constant power voltage range ΔU2, the energy storage device maintains its own power, and the AFE device first increases its own power. If the power in the DC microgrid is still insufficient and the DC bus voltage drops further, the energy storage device may find that the DC bus voltage is now in its drooping voltage range ΔU3, and the energy storage device reduces its charging power. If the power in the DC microgrid is still insufficient and the DC bus voltage drops further, the energy storage device begins to discharge. If the power in the DC microgrid is still insufficient and the DC bus voltage drops further, the charging power of the charging pile can be limited.

[0034] In some embodiments, taking a stable state with a current bus voltage of 750V as an example, when there is excess power in the DC microgrid and the DC bus voltage rises, if the energy storage device determines that the DC bus voltage is still within its constant power voltage range ΔU2, the energy storage device maintains its own power, and the AFE device first reduces its own power. If the power in the DC microgrid is still excessive and the DC bus voltage rises further, the energy storage device may find that the DC bus voltage is now within its droop voltage range ΔU1, and the energy storage device can increase its own charging power. If the power in the DC microgrid is still excessive and the DC bus voltage rises further, but the energy storage device has reached its charging power limit, the power of the photovoltaic device can be limited.

[0035] By adopting energy storage devices for DC microgrids, such as... Figures 2A-2C The power-voltage curve shown can realize peak shaving and valley filling of DC microgrids, thereby optimizing the economy of DC microgrids.

[0036] Figures 3A-3C Power-voltage graphs of various devices in a DC microgrid applying constant power droop for energy storage devices and charging piles, according to embodiments of the present disclosure, are shown. Figure 3A The power-voltage curves of various devices in a DC microgrid are described during energy storage charging. Figure 3B The power-voltage curves of various devices in a DC microgrid are described during energy storage backup. Figure 3C The power-voltage curves of various devices in a DC microgrid are described during energy storage charging.

[0037] like Figures 3A-3C As shown, the horizontal axis represents the power of each device in the DC microgrid, and the vertical axis represents the voltage of the DC bus. Different curves are used for different devices, and each device can adjust its own power and voltage based on the curves when the DC microgrid has excess power (DC bus voltage drops) or insufficient power (DC bus voltage rises).

[0038] refer to Figure 3A Energy storage devices can have a power-voltage curve S1, photovoltaic devices can have a power-voltage curve S2, charging pile loads can have a power-voltage curve S3, and AFE devices can have a power-voltage curve S4. From Figure 3A It can be seen that both the energy storage device and the charging pile load are configured with constant power droop. However, this disclosure is not limited to this; any power-adjustable device in a DC microgrid can be configured with constant power droop.

[0039] In some embodiments, the energy storage device and the charging pile load can be pre-configured with their respective constant power voltage range and droop voltage range. When the voltage on the DC bus is within the constant power voltage range of the energy storage device, the power of the energy storage device can maintain a specific power. When the voltage on the DC bus is within the droop voltage range of the energy storage device, the power and voltage of the energy storage device can be adjusted based on a power-voltage curve. Similarly, when the voltage on the DC bus is within the constant power voltage range of the charging pile load, the power of the charging pile load can maintain a specific power. When the voltage on the DC bus is within the droop voltage range of the charging pile load, the power and voltage of the charging pile load can be adjusted based on a power-voltage curve. In some embodiments, this specific power can be configured by the microgrid controller and is not zero. Furthermore, this specific power should be between the maximum charging power and the maximum discharging power of the energy storage device.

[0040] like Figure 3A As shown, energy storage devices can have constant power voltage ranges △U2 and △U4, and droop voltage ranges △U1, △U3, and △U5, while charging pile loads can have constant power voltage range △U6 and droop voltage ranges △U8 and △U7. It can be understood that, depending on the configured constant power voltage range, droop voltage range, and the magnitude of the specific power, energy storage devices and charging pile loads can adjust their power and voltage according to power-voltage curves with different slopes within the droop voltage range.

[0041] In some embodiments, taking a stable state with a current bus voltage of 750V as an example, when the power in the DC microgrid is insufficient and the DC bus voltage drops, if the energy storage device determines that the DC bus voltage is still within its constant power voltage range △U4 and the charging pile load determines that the DC bus voltage is still within its constant power voltage range △U6, then the energy storage device and the charging pile load maintain their own power, and the AFE device first increases its own power. If the power in the DC microgrid is still insufficient and the DC bus voltage drops further, the energy storage device may find that the DC bus voltage is now in its drooping voltage range △U5 and the charging pile load may determine that the DC bus voltage is still within its constant power voltage range △U6. In this case, the energy storage device increases its own discharge power while the charging pile load maintains its own power. If the power in the DC microgrid is still insufficient and the DC bus voltage drops further, but the power of the energy storage device has reached its upper limit of discharge power, and the charging pile load may determine that the DC bus voltage is now in its drooping voltage range △U7, then the charging power of the charging pile load can decrease.

[0042] In some embodiments, taking a stable state with a current bus voltage of 750V as an example, when there is excess power in the DC microgrid and the DC bus voltage rises, if the energy storage device determines that the DC bus voltage is still within its constant power voltage range △U4 and the charging pile load determines that the DC bus voltage is still within its constant power voltage range △U6, then the energy storage device and the charging pile load maintain their own power, and the AFE device first reduces its own power. If there is still excess power in the DC microgrid and the DC bus voltage rises further, the energy storage device may find that the DC bus voltage is now within its drooping voltage range △U3 and the charging pile load may determine that the DC bus voltage is still within its constant power voltage range △U6. The energy storage device can reduce its own discharge power while the charging pile load maintains its own power. If there is still excess power in the DC microgrid and the DC bus voltage rises further, the energy storage device may find that the DC bus voltage is now within its drooping voltage range △U1, and the energy storage device can begin charging. If the power in the DC microgrid is still excessive and the DC bus voltage rises further, and the charging pile load may find that the DC bus voltage is in its droop voltage range ΔU8, the charging power of the charging pile load can increase. If the power in the DC microgrid is still excessive and the DC bus voltage rises further, the power of the photovoltaic equipment can be limited.

[0043] refer to Figure 3B ,and Figure 3A Similarly, energy storage devices can have a power-voltage curve S1, photovoltaic devices can have a power-voltage curve S2, charging pile loads can have a power-voltage curve S3, and AFE devices can have a power-voltage curve S4. However, with Figure 3A Unlike other devices, energy storage devices are configured with a constant power droop of zero power, which can be fitted as a droop, while charging pile loads are still configured with a constant power droop of non-zero power.

[0044] In some embodiments, taking a stable state with a current bus voltage of 750V as an example, when the power in the DC microgrid is insufficient and the DC bus voltage drops, if the energy storage device determines that the DC bus voltage is still within its constant power voltage range △U2 and the charging pile load determines that the DC bus voltage is still within its constant power voltage range △U6, then the energy storage device maintains its own power, i.e., remains in standby mode, and the charging pile load maintains its charging power, with the AFE device first increasing its own power. If the power in the DC microgrid is still insufficient and the DC bus voltage drops further, the energy storage device may find that the DC bus voltage is still within its constant power voltage range △U2 and the charging pile load may find that the DC bus voltage is in its drooping voltage range △U7, then the energy storage device remains in standby mode while the charging pile load begins to reduce its charging power. If the power in the DC microgrid is still insufficient and the DC bus voltage drops further, the energy storage device may find that the DC bus voltage is in its drooping voltage range △U3, then the energy storage device begins to discharge.

[0045] In some embodiments, taking a stable state with a current bus voltage of 750V as an example, when there is excess power in the DC microgrid and the DC bus voltage rises, if the energy storage device determines that the DC bus voltage is still within its constant power voltage range △U2 and the charging pile load determines that the DC bus voltage is still within its constant power voltage range △U6, then the energy storage device maintains its own power, i.e., remains in standby mode, and the charging pile load maintains its charging power, with the AFE device first reducing its own power. If there is still excess power in the DC microgrid and the DC bus voltage rises further, the energy storage device may find that the DC bus voltage is still within its constant power voltage range △U2 and the charging pile load may find that the DC bus voltage is in its drooping voltage range △U8, then it remains in standby mode while the charging pile load begins to increase its charging power. If there is still excess power in the DC microgrid and the DC bus voltage rises further, the energy storage device may find that the DC bus voltage is in its drooping voltage range △U1, and the energy storage device can begin charging. If there is still excess power in the DC microgrid and the voltage of the DC bus rises further, the power of the photovoltaic equipment can be limited.

[0046] refer to Figure 3C ,and Figure 3A Similarly, energy storage devices can have a power-voltage curve S1, photovoltaic devices can have a power-voltage curve S2, charging pile loads can have a power-voltage curve S3, and AFE devices can have a power-voltage curve S4. However, with Figure 3A Unlike other energy storage devices, energy storage devices are configured to maintain a specific power level below zero within a constant power voltage range.

[0047] In some embodiments, taking a stable state with a current bus voltage of 750V as an example, when the power in the DC microgrid is insufficient and the DC bus voltage drops, if the energy storage device determines that the DC bus voltage is still within its constant power voltage range △U2 and the charging pile load determines that the DC bus voltage is still within its constant power voltage range △U6, then the energy storage device maintains its own power, the charging pile load maintains its charging power, and the AFE device first increases its own power. If the power in the DC microgrid is still insufficient and the DC bus voltage drops further, the energy storage device may find that the DC bus voltage is now in its drooping voltage range △U3 and the charging pile load determines that the DC bus voltage is still within its constant power voltage range △U6, then the energy storage device reduces its charging power, and the charging pile load maintains its charging power. If the power in the DC microgrid is still insufficient and the DC bus voltage drops further, the charging pile load may find that the DC bus voltage is now in its drooping voltage range △U7, then the charging pile load begins to reduce its charging power. If the power in the DC microgrid is still insufficient and the DC bus voltage drops further, the energy storage device begins to discharge.

[0048] In some embodiments, taking a stable state with a current bus voltage of 750V as an example, when there is excess power in the DC microgrid and the DC bus voltage rises, if the energy storage device determines that the DC bus voltage is still within its constant power voltage range △U2 and the charging pile load determines that the DC bus voltage is still within its constant power voltage range △U6, then the energy storage device maintains its own power, the charging pile load maintains its charging power, and the AFE device first reduces its own power. If there is still excess power in the DC microgrid and the DC bus voltage rises further, the energy storage device may find that the DC bus voltage is still within its constant power voltage range △U2, but the charging pile load may find that the DC bus voltage is in its drooping voltage range △U8. In this case, the energy storage device maintains its own power, and the charging pile load increases its charging power. If there is still excess power in the DC microgrid and the DC bus voltage rises further, the energy storage device may find that the DC bus voltage is in its drooping voltage range △U1. In this case, the energy storage device can increase its own charging power. If there is still excess power in the DC microgrid and the voltage of the DC bus rises further, but the energy storage device has reached its charging power limit, then the power of the photovoltaic device can be limited.

[0049] By adopting energy storage devices for DC microgrids, such as... Figures 3A-3C The power-voltage curve shown enables load tracking of the DC microgrid, thereby optimizing the economy of the DC microgrid.

[0050] Figure 4The following diagram illustrates the power-voltage plots of various devices in a DC microgrid where constant power droop is applied to the active front-end (AFE) devices, according to embodiments of the present disclosure.

[0051] like Figure 4 As shown, energy storage devices can have a power-voltage curve S1, photovoltaic devices can have a power-voltage curve S2, charging pile loads can have a power-voltage curve S3, and AFE devices can have a power-voltage curve S4. From Figure 4 It can be seen that only the AFE device is configured with constant power droop. However, this disclosure is not limited thereto; any power-adjustable device in a DC microgrid can be configured with constant power droop.

[0052] In some embodiments, to achieve constant power at the point of common coupling (PCC), it is typically necessary to keep the AFE device at a constant power level, even if the AFE device has the highest constant power priority. Therefore, the constant power voltage range of the AFE device needs to be set as large as possible. For example, when multiple devices in a DC microgrid are configured with constant power droop, the constant power voltage range of the AFE device should be configured to be the largest constant power voltage range among the multiple devices.

[0053] refer to Figure 4 The AFE device is configured with a constant power voltage range ΔU2. In some embodiments, taking a stable state with a current bus voltage of 750V as an example, it can be seen that regardless of whether the DC microgrid has excess power and the bus voltage rises, or the DC microgrid has insufficient power and the bus voltage drops, the power of the AFE device can remain constant within the constant power voltage range ΔU2. Furthermore, because its constant power voltage range ΔU2 is set to the maximum, the power of the AFE device is only adjusted when all other devices in the DC microgrid, after adjusting their own power and voltage, still cannot bring the DC microgrid to a balanced state.

[0054] By adopting, for example, the AFE equipment of the DC microgrid Figure 4 The power-voltage curve shown can achieve constant power PCC of DC microgrid, thereby optimizing the economy of DC microgrid.

[0055] Figure 5 A schematic diagram illustrating constant power droop achieved by an energy storage device according to an embodiment of the present disclosure is shown.

[0056] refer to Figure 5 The diagram illustrates the switching between constant power mode and droop mode when an energy storage device configured with constant power droop is discharging. However, this disclosure is not limited thereto; similar mode switching can be applied to energy storage device charging, standby, and any other device configured with constant power droop.

[0057] like Figure 5As shown, the power-voltage curves for energy storage device discharge include Mode 1-1, Mode 1-2, and Mode 1-3. In some embodiments, the microgrid controller configures the power-voltage curves for the energy storage device (i.e., configures a constant power voltage range, a droop voltage range, and a specific power). The energy storage device initially operates in Mode 1-1. When the DC microgrid is operating normally (bus voltage is 750V), the energy storage device operates at full power in Mode 1-1 (i.e., the bus voltage is in the constant power voltage range of the energy storage device, and the energy storage device maintains a constant specific power). If the system power is excessive, the AFE device is unloaded, and the system voltage rises, the energy storage device enters the droop segment of Mode 1-1, i.e., actively reduces the discharge power to maintain system power balance. If the energy storage device's discharge power decreases to zero, but the DC microgrid power is still excessive and the DC bus voltage continues to rise, the energy storage device actively switches its operating mode to Mode 1-3 according to the DC bus voltage, i.e., the energy storage device begins charging. In some embodiments, if the energy storage device operates at full power in mode 1-1 (i.e., the bus voltage is in the constant power voltage range of the energy storage device and the energy storage device maintains a specific power constant), the system power is insufficient, the AFE device is fully loaded, and the system voltage drops, then the energy storage device actively switches the operating mode to mode 1-2 according to the DC bus voltage.

[0058] In some embodiments, devices in a DC microgrid can first stabilize their own power and then stabilize their own voltage according to a power-voltage curve. For example, devices can adjust their own voltage in a step-by-step manner to avoid sudden voltage changes.

[0059] Figure 6 A power control method for a DC microgrid according to an embodiment of the present disclosure is illustrated. The DC microgrid may include a DC bus and a plurality of devices connected to the DC bus, at least one of which can perform [operation / function]. Figure 6 The method shown.

[0060] like Figure 6 As shown, in step S610, at least one of the multiple devices can detect the voltage on the DC bus and the power of that device. When the power in the DC microgrid is insufficient or excessive, the voltage on the DC bus will fluctuate, and the device connected to the DC bus can detect the change in power in the DC microgrid by detecting the voltage on the DC bus.

[0061] In step S620, based on the DC bus voltage being within a constant power voltage range, the at least one device can maintain its power at a specific power. In some embodiments, at least one of a plurality of devices can be configured with a constant power voltage range, and when the DC bus voltage is within the constant power voltage range, the at least one device can maintain a specific power. The specific power can be configured as a non-zero power. For example, for an energy storage device that is charging, the specific power can be configured to be less than zero, and for an energy storage device that is discharging, the specific power can be configured to be greater than zero.

[0062] In step S630, based on the DC bus voltage being within a droop voltage range, the at least one device can adjust its power and voltage. In some embodiments, at least one of the plurality of devices can be configured with a droop voltage range, and when the DC bus voltage is within the droop voltage range, the at least one device can adjust its power and voltage. For example, when the at least one device is configured with a constant power voltage range, a droop voltage range, and a specific power, a power-voltage curve can be determined based on its own upper and lower power limits, and its own power and voltage can be adjusted based on the power-voltage curve.

[0063] Those skilled in the art will recognize that the units and algorithm steps of the various embodiments described in conjunction with the embodiments disclosed in this invention can be implemented in electronic hardware, computer software, or a combination of both. To clearly illustrate the interchangeability of hardware and software, the composition and steps of each embodiment have been generally described in terms of functionality in the foregoing description. Whether these functions are implemented in hardware or software depends on the specific application and design constraints of the technical solution. Those skilled in the art can use different methods to implement the described functions for each specific application, but such implementation should not be considered beyond the scope of this invention.

[0064] Those skilled in the art will understand that, for the sake of convenience and brevity, the specific working processes of the systems, devices, and units described above can be referred to the corresponding processes in the foregoing method embodiments, and will not be repeated here.

[0065] In the embodiments provided by this invention, it should be understood that the disclosed systems, apparatuses, and methods can be implemented in other ways. For example, the apparatus embodiments described above are merely illustrative; for instance, the division of units is only a logical functional division, and in actual implementation, there may be other division methods. For example, multiple units or components may be combined or integrated into another system, or some features may be ignored or not executed. Furthermore, the coupling or direct coupling or communication connection shown or discussed may be through some interfaces; the indirect coupling or communication connection between devices or units may be electrical, mechanical, or other forms.

[0066] The units described as separate components may or may not be physically separate. The components shown as units may or may not be physical units; they may be located in one place or distributed across multiple network units. Some or all of the units can be selected to achieve the purpose of this embodiment, depending on actual needs.

[0067] Furthermore, the functional units in the various embodiments of the present invention can be integrated into one processing unit, or each unit can exist physically separately, or two or more units can be integrated into one unit. The integrated unit can be implemented in hardware or as a software functional unit.

[0068] If the integrated unit is implemented as a software functional unit and sold or used as an independent product, it can be stored in a computer-readable storage medium. Based on this understanding, the technical solution of the present invention, in essence, or the part that contributes to the prior art, or all or part of the technical solution, can be embodied in the form of a software product. This computer software product is stored in a storage medium and includes several instructions to cause a computer device (which may be a personal computer, server, or network device, etc.) to execute all or part of the steps of the methods described in the various embodiments of the present invention. The aforementioned storage medium includes various media capable of storing program code, such as USB flash drives, portable hard drives, read-only memory (ROM), random access memory (RAM), magnetic disks, or optical disks.

[0069] The above description is merely a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in the present invention should be included within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the scope of the claims.

Claims

1. A DC microgrid, the DC microgrid comprising: DC bus; as well as Multiple devices are connected to the DC bus, wherein at least one of the multiple devices is configured to: Detect the voltage on the DC bus and the power of the device; Based on the fact that the voltage on the DC bus is within a constant power voltage range, the power of the device is maintained at a specific power; and Based on the fact that the voltage on the DC bus is within the droop voltage range, the power and voltage of the equipment are adjusted. Wherein, the specific power is not zero.

2. The DC microgrid according to claim 1, wherein, The constant power voltage range and the droop voltage range are pre-configured.

3. The DC microgrid according to claim 1, wherein, The DC microgrid also includes a microgrid controller, and the specific power is received by the device from the microgrid controller.

4. The DC microgrid according to claim 1, wherein, The specific power is within the adjustable power range of the device.

5. The DC microgrid according to claim 1, wherein, The plurality of devices include active front-end (AFE) devices, wherein the AFE devices have the largest constant power voltage range.

6. The DC microgrid according to claim 5, wherein, When the voltage on the DC bus changes, the AFE device is the last among the plurality of devices to perform power adjustment.

7. The DC microgrid according to claim 1, wherein, Adjusting the power and voltage of the device based on the voltage on the DC bus being within the droop voltage range includes: Based on the current power and voltage of the device and the power-voltage relationship, determine the target power and target voltage of the device; and Adjust the power and voltage of the device to the target power and target voltage.

8. The DC microgrid according to claim 7, wherein, The power-voltage relationship is a linear function, and the slope of the linear function is determined based on the constant power voltage range, the drooping voltage range, and the specific power.

9. A power control method for a DC microgrid, the DC microgrid comprising a DC bus and a plurality of devices connected to the DC bus, wherein for at least one of the plurality of devices, the method comprises: Detect the voltage on the DC bus and the power of the device; Based on the fact that the voltage on the DC bus is within the constant power voltage range, the power of the device is maintained at a specific power. as well as Based on the fact that the voltage on the DC bus is within the droop voltage range, the power and voltage of the equipment are adjusted. Wherein, the specific power is not zero.

10. The method according to claim 9, wherein, The constant power voltage range and the droop voltage range are pre-configured.

11. The method according to claim 9, wherein, The DC microgrid also includes a microgrid controller, and the specific power is received by the device from the microgrid controller.

12. The method according to claim 9, wherein, The specific power is within the adjustable power range of the device.

13. The method according to claim 9, wherein, The plurality of devices include active front-end (AFE) devices, wherein the AFE devices have the largest constant power voltage range.

14. The method according to claim 13, wherein, When the voltage on the DC bus changes, the AFE device is the last among the plurality of devices to perform power adjustment.

15. The method according to claim 1, wherein, Adjusting the power and voltage of the device based on the voltage on the DC bus being within the droop voltage range includes: Based on the current power and voltage of the device and the power-voltage relationship, determine the target power and target voltage of the device; and Adjust the power and voltage of the device to the target power and target voltage.

16. The method according to claim 15, wherein, The power-voltage relationship is a linear function, and the slope of the linear function is determined based on the constant power voltage range, the drooping voltage range, and the specific power.

17. A computer-readable storage medium having stored thereon computer-executable instructions, which, when executed by a processing unit, are used to implement the method of any one of claims 9-16.

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