Electric energy dispatching system and electric energy dispatching method

Abstract

The embodiment of the invention discloses an electric energy dispatching system and an electric energy dispatching method. According to one specific embodiment, the system comprises a control end, a micro-grid and a main power grid, wherein the micro-grid comprises photovoltaic power generation equipment, battery energy storage equipment and a load end; each piece of photovoltaic power generation equipment and each piece of battery energy storage equipment are connected to the direct-current bus in a direct-current side coupling mode; the control end is configured to execute the following control steps: performing fault detection processing on a main power grid to obtain main power grid fault detection information; in response to determining that the main power grid fault detection information represents that the main power grid does not have a fault, executing the following grid-connected power dispatching processing: collecting photovoltaic power generation output power information and load power information; each battery energy storage device is controlled to be charged or discharged so as to execute inter-network and in-network layered cooperative electric energy scheduling processing; and in response to determining that the main power grid fault detection information represents that the main power grid has a fault, executing electric energy scheduling processing in the micro-grid. According to the embodiment, energy waste is reduced.

Description

Technical Field

[0001] The embodiments disclosed herein relate to the field of power grid technology, specifically to power dispatching systems and power dispatching methods. Background Technology

[0002] With the increasing demand for electricity and the growing complexity of power grid structures, power dispatch systems have been widely applied in all aspects of power production and supply. A power dispatch system is a system for scheduling electrical energy. Currently, the common approach to power dispatch is to determine the power interaction between the microgrid and the main grid by setting fixed power thresholds. For example, when the total power generated by photovoltaics in the microgrid exceeds a preset upper limit, the excess power is transmitted to the main grid; when the photovoltaic power generation is below a preset lower limit, power is obtained from the main grid to meet the load demand within the microgrid.

[0003] However, when using the above method for power dispatch, the following technical problems often arise:

[0004] Setting a fixed power threshold to determine the power interaction between the microgrid and the main grid simply involves transmitting excess power from the microgrid to the main grid, or drawing power from the main grid to meet the load demand within the microgrid when photovoltaic power supply is insufficient (when photovoltaic power generation is below a preset lower limit). This approach does not consider the impact of energy storage device charging or discharging on power dispatch, nor can it reasonably supplement power based on the actual situation of photovoltaic power generation and load power consumption within the microgrid. This leads to increased energy waste or supply-demand mismatch, resulting in low energy utilization efficiency.

[0005] The information disclosed in this background section is only intended to enhance the understanding of the background of the inventive concept, and therefore may contain information that does not form prior art known to those skilled in the art. Summary of the Invention

[0006] The summary portion of this disclosure is intended to provide a brief overview of the concepts, which will be described in detail in the detailed description portion. This summary portion is not intended to identify key or essential features of the claimed technical solutions, nor is it intended to limit the scope of the claimed technical solutions.

[0007] Some embodiments of this disclosure propose power dispatching systems and methods to address one or more of the technical intentions mentioned in the background section above.

[0008] In a first aspect, some embodiments of this disclosure provide a power dispatching system, which includes: a control terminal, a microgrid, and a main grid, wherein: the microgrid includes various photovoltaic power generation devices, various battery energy storage devices, and load terminals; the various photovoltaic power generation devices and the various battery energy storage devices are connected to a DC bus via DC-side coupling, wherein the load terminals are connected to the DC bus via a first three-phase inverter, and the DC bus is connected to the main grid via a second three-phase inverter; the control terminal is configured to perform the following control steps: perform fault detection processing on the main grid to obtain main grid fault detection information; in response to determining that the main grid fault detection information indicates that no fault has occurred in the main grid, perform the following grid-connected power dispatching processing: collect photovoltaic power generation output power information of the various photovoltaic power generation devices and load power information of the load terminals; based on the photovoltaic power generation output power information and the load power information, control the charging or discharging of the various battery energy storage devices to perform inter-grid and intra-grid hierarchical collaborative power dispatching processing; in response to determining that the main grid fault detection information indicates that a fault has occurred in the main grid, perform power dispatching processing within the microgrid.

[0009] Secondly, some embodiments of this disclosure provide a power dispatching method, which includes: performing fault detection processing on the main power grid to obtain main power grid fault detection information; in response to determining that the main power grid fault detection information indicates that no fault has occurred in the main power grid, performing the following grid-connected power dispatching processing: collecting photovoltaic power output power information of each photovoltaic power generation device and load power information of the load end; based on the photovoltaic power output power information and the load power information, controlling each battery energy storage device to charge or discharge, so as to perform inter-grid and intra-grid hierarchical collaborative power dispatching processing; and in response to determining that the main power grid fault detection information indicates that a fault has occurred in the main power grid, performing microgrid power dispatching processing.

[0010] The various embodiments disclosed above have the following beneficial effects: the power dispatch system of some embodiments of this disclosure reduces energy waste or supply-demand mismatch and improves energy utilization efficiency. Specifically, the reasons for energy waste, supply-demand mismatch, and low energy utilization efficiency are as follows: setting a fixed power threshold to determine the power interaction between the microgrid and the main grid simply involves transmitting excess power from the microgrid exceeding the upper limit to the main grid, or obtaining power from the main grid to meet the load demand within the microgrid when photovoltaic power supply is insufficient (when photovoltaic power generation is below a preset lower limit). This does not consider the impact of energy storage device charging or discharging on power dispatch, nor can it reasonably supplement power based on the actual situation of photovoltaic power generation and load power consumption within the microgrid, leading to increased energy waste or supply-demand mismatch and low energy utilization efficiency. Based on this, some embodiments of the power dispatch system disclosed herein include: a control terminal, a microgrid, and a main grid, wherein: the microgrid includes various photovoltaic power generation devices, various battery energy storage devices, and a load terminal; the various photovoltaic power generation devices and the various battery energy storage devices are connected to a DC bus via DC-side coupling; the load terminal is connected to the DC bus via a first three-phase inverter; and the DC bus is connected to the main grid via a second three-phase inverter. Thus, independent control of intra-grid and inter-grid energy flow can be achieved through dual inverters (the first three-phase inverter is connected to the load, and the second three-phase inverter is connected to the main grid). The control terminal is configured to perform the following control steps: perform fault detection processing on the main grid to obtain main grid fault detection information. Thus, fault detection can be performed on the main grid to generate main grid fault detection information for determining whether to perform grid-connected power dispatch processing or microgrid-based power dispatch processing. Subsequently, in response to the confirmation that the main grid fault detection information indicates no fault has occurred in the main grid, the following grid-connected power dispatching process is executed: Photovoltaic power output information of each photovoltaic power generation device and load power information of the load terminals are collected. This allows for the collection of photovoltaic power output and load power information. Then, based on this photovoltaic power output and load power information, the charging or discharging of each battery energy storage device is controlled to perform hierarchical coordinated power dispatching between and within the grid. Thus, based on the collected photovoltaic power output and load power information, priority can be given to controlling each battery energy storage device to store excess electricity or supply power to the load terminals to supplement load gaps. Controlling the charging and discharging of energy storage devices avoids simply sending excess power into the main grid or relying solely on the main grid when photovoltaic power generation is insufficient. Energy storage devices provide a buffer for the microgrid; regulating the charging and discharging of energy storage devices solves problems such as energy storage not participating in dispatching decisions and supply-demand matching lag in traditional power dispatching. Power is stored when photovoltaic power generation is excessive and released when photovoltaic power generation is insufficient.After each battery energy storage device is charged or discharged, hierarchical collaborative power dispatching between and within the grid is performed, taking into account the impact of the charging or discharging status of the energy storage devices on power dispatching. In response to the determination of main grid fault detection information indicating a main grid fault, power dispatching within the microgrid is executed. Therefore, when a main grid fault occurs, the microgrid can maintain independent operation and automatically adjust power flow according to photovoltaic power generation and load demand. In this way, even if the main grid cannot supply power normally, the microgrid can still ensure stable power supply through intelligent dispatching, avoiding power outages. Furthermore, the use of DC-coupled dual inverters (the first three-phase inverter connects to the load, and the second three-phase inverter connects to the main grid) enables independent control of energy flow between and within the grid, allowing the microgrid to automatically switch between grid-connected (hierarchical collaborative power dispatching between and within the grid) or off-grid mode (power dispatching within the microgrid) based on the main grid fault status. Furthermore, based on the collected photovoltaic power output and load power information, the charging and discharging behavior of the battery energy storage equipment is dynamically controlled. The energy storage is used to prioritize the balance of supply and demand within the grid (charging when there is excess photovoltaic power and discharging when there is insufficient power). This reduces energy waste caused by "simply sending out excess power" or "over-reliance on the main grid", ensures stable system operation, and improves the efficiency of power dispatch and energy utilization. Attached Figure Description

[0011] The above and other features, advantages, and aspects of the embodiments of this disclosure will become more apparent from the accompanying drawings and the following detailed description. Throughout the drawings, the same or similar reference numerals denote the same or similar elements. It should be understood that the drawings are schematic, and elements are not necessarily drawn to scale.

[0012] Figure 1 This is an architecture diagram of an exemplary system for a power dispatching system based on this disclosure;

[0013] Figure 2 Flowcharts of some embodiments of the power dispatching method according to this disclosure. Detailed Implementation

[0014] Embodiments of this disclosure will now be described in more detail with reference to the accompanying drawings. While some embodiments of this disclosure are shown in the drawings, it should be understood that this disclosure can be implemented in various forms and should not be construed as limited to the embodiments set forth herein. Rather, these embodiments are provided to provide a more thorough and complete understanding of this disclosure. It should be understood that the accompanying drawings and embodiments of this disclosure are for illustrative purposes only and are not intended to limit the scope of protection of this disclosure.

[0015] It should also be noted that, for ease of description, only the parts relevant to the invention are shown in the accompanying drawings. Unless otherwise specified, the embodiments and features described in this disclosure can be combined with each other.

[0016] It should be noted that the concepts of "first" and "second" mentioned in this disclosure are used only to distinguish different devices, modules or units, and are not used to limit the order of functions performed by these devices, modules or units or their interdependencies.

[0017] It should be noted that the terms "a" and "a plurality of" used in this disclosure are illustrative rather than restrictive, and those skilled in the art should understand that, unless otherwise expressly indicated in the context, they should be understood as "one or more".

[0018] The names of messages or information exchanged between multiple devices in the embodiments of this disclosure are for illustrative purposes only and are not intended to limit the scope of such messages or information.

[0019] This disclosure will now be described in detail with reference to the accompanying drawings and embodiments.

[0020] Figure 1 An exemplary system architecture 100 of a heterogeneous data exchange system to which some embodiments of the present disclosure may be applied is shown.

[0021] like Figure 1As shown, the system architecture 100 may include: a control terminal 103, a microgrid 101, and a main grid 102. The microgrid 101 includes various photovoltaic power generation devices 1012, various battery energy storage devices 1013, and a load terminal 1011. The photovoltaic power generation devices 1012 and the battery energy storage devices 1013 are connected to a DC bus via DC-side coupling. The load terminal is connected to the DC bus via a first three-phase inverter, and the DC bus is connected to the main grid 102 via a second three-phase inverter. The control terminal 103 may be a computing device (e.g., a server) for controlling and scheduling the flow of electricity within the microgrid and between the microgrid and the main grid. The control terminal 103 can collect various data (such as photovoltaic power generation, load terminal power, etc.) through communication with the microgrid and the main grid, and make scheduling decisions based on this data. Each photovoltaic power generation device 1012 may be a photovoltaic module (e.g., a solar panel) in a photovoltaic array. Each of the aforementioned battery energy storage devices 1013 can be an energy storage battery. The aforementioned load end 1011 includes various preset priority load devices and various preset non-priority load devices. The preset non-priority load devices include at least one variable frequency speed control load device and at least one constant load device. Each of the aforementioned preset priority load devices can be a device that receives priority power supply during power dispatching. Each of the aforementioned preset non-priority load devices can be a device that can delay or cut off power supply during peak power demand or power shortages. Each of the aforementioned at least one variable frequency speed control load device can be a device that adjusts its operating frequency (e.g., a water pump). Each of the aforementioned at least one constant load device can be a device whose operating power does not change (e.g., a street light). The aforementioned first three-phase inverter can be a three-phase inverter located between the load end and the DC bus. One of the aforementioned second three-phase inverters can be a three-phase inverter between the microgrid and the main grid. The aforementioned main grid can be a main grid connected to the microgrid.

[0022] In some embodiments, the control terminal 103 can be configured to perform the following control steps:

[0023] First, fault detection processing is performed on the aforementioned main power grid to obtain main power grid fault detection information. In practice, the control terminal can collect key electrical parameters of the main power grid in real time, such as voltage, current, and frequency, and then compare these parameters with preset thresholds or normal ranges to determine whether a fault has occurred, thus obtaining main power grid fault detection information. This main power grid fault detection information can be textual information indicating whether a fault has occurred in the main power grid, and can be represented by Boolean values ​​(e.g., 0 (False): indicating no fault has occurred, 1 (True): indicating a fault has occurred). Optionally, the control terminal can monitor the status information of each circuit breaker in the main power grid. In response to determining that at least one status information indicating a circuit breaker trip exists, the information indicating a fault in the main power grid is determined as main power grid fault detection information. In response to determining that no status information indicating a circuit breaker trip exists, the information indicating no fault has occurred in the main power grid is determined as main power grid fault detection information. Each status information can represent the status of its corresponding circuit breaker (e.g., no trip or tripped).

[0024] Second, in response to the determination that the main grid fault detection information indicates that no fault has occurred in the main grid, the following grid-connected power dispatching procedures are performed:

[0025] Step 1: Collect the photovoltaic power output information of each of the above photovoltaic power generation devices and the load power information of the above load terminals.

[0026] In some embodiments, the control terminal 103 can collect photovoltaic power output information of each photovoltaic power generation device and load power information of the load terminal. The photovoltaic power output information can represent the total output power of each photovoltaic power generation device. The load power information can represent the electrical power consumed or used by the load terminal.

[0027] In some optional implementations of certain embodiments, the control terminal 103 may perform the following steps to collect the photovoltaic power output information of each of the photovoltaic power generation devices and the load power information of the load terminal:

[0028] The first step is to perform the following data collection steps for each of the aforementioned photovoltaic power generation devices:

[0029] The first sub-step involves acquiring photovoltaic output voltage information via a voltage sensor at the DC output terminal of the aforementioned photovoltaic power generation equipment, and acquiring photovoltaic output current information via a current sensor at the DC output terminal of the aforementioned photovoltaic power generation equipment. The photovoltaic output voltage information represents the voltage at the DC output terminal of the photovoltaic power generation equipment (e.g., 35V). The photovoltaic output current information represents the current at the DC output terminal of the photovoltaic power generation equipment (e.g., 8A).

[0030] The second sub-step generates the output power information of a single power generation device based on the aforementioned photovoltaic output voltage and photovoltaic output current information. In practice, the control terminal can determine the output power information of a single power generation device by multiplying the voltage represented by the photovoltaic output voltage information by the current represented by the photovoltaic output current information. As an example, the output power information of a single power generation device = 35V × 8A = 280W.

[0031] The second step is to generate photovoltaic power output information corresponding to each of the aforementioned photovoltaic power generation devices based on the obtained output power information of each individual power generation device. In practice, the control terminal can determine the sum of the individual powers represented by the output power information of each individual power generation device as the photovoltaic power output information corresponding to each of the aforementioned photovoltaic power generation devices.

[0032] The third step is to collect the three-phase power information from the output side of the first three-phase inverter connected to the aforementioned load terminal as the load power information. In practice, the control terminal can collect the three-phase power information from the output side of the first three-phase inverter connected to the aforementioned load terminal using a three-phase power meter or smart meter. The aforementioned three-phase power meter or smart meter can be installed at the output terminal of the first three-phase inverter.

[0033] Step 2: Based on the photovoltaic power output information and the load power information mentioned above, control the charging or discharging of each battery energy storage device to perform inter-grid and intra-grid hierarchical collaborative power dispatching.

[0034] In some embodiments, the control terminal 103 can be further configured to control the charging or discharging of each battery energy storage device based on the photovoltaic power output information and the load power information through the following steps, so as to perform inter-grid and intra-grid hierarchical collaborative power dispatch processing:

[0035] The first step, in response to the determination that the output power represented by the photovoltaic power generation output power information is equal to zero, is to perform scheduling processing under the condition of no photovoltaic output:

[0036] The first sub-step involves controlling each of the aforementioned battery energy storage devices to discharge to the aforementioned DC bus. In practice, the control terminal can estimate the SOC value of each battery energy storage device as the battery availability rate of each battery energy storage device using a state observer. Then, the average of the battery availability rates can be determined as the overall battery availability rate of each battery energy storage device. In response to determining that the overall battery availability rate is greater than a preset value (e.g., 40%), the control terminal can determine at least one battery availability rate among the various battery availability rates that is greater than the preset availability rate threshold as at least one screened battery availability rate. Then, the control terminal can determine the sum of the at least one screened battery availability rate as a first value. Then, for each of the at least one screened battery availability rates, the control terminal can determine the ratio of the screened battery availability rate to the first value as a second value. Then, the control terminal can determine the output power as the product of the second value and the electrical power represented by the load power information. Next, the control terminal can control the battery energy storage device corresponding to the screened battery availability rate to output the amount of electricity corresponding to the output power. Among them, each of the above battery availability rates can be the percentage ratio of the current available power of the battery energy storage device to its rated total capacity.

[0037] The second sub-step involves performing the following data collection steps for each of the aforementioned battery energy storage devices:

[0038] The first step involves acquiring energy storage voltage information through voltage sensors at the DC input and output terminals of the aforementioned battery energy storage device, and acquiring energy storage current information through bidirectional current sensors at the DC input and output terminals of the same device. The energy storage voltage information represents the voltage at the DC input and output terminals of the battery energy storage device. The current information represents the current at the DC input and output terminals of the battery energy storage device. It should be noted that the current value is negative when the battery energy storage device is charging, and positive when it is discharging.

[0039] The second step involves generating single-energy storage device power information based on the aforementioned energy storage voltage and current information. In practice, the control unit can determine the single-energy storage device power as the product of the voltage represented by the energy storage voltage information and the current value represented by the energy storage current information. (It should be noted that during charging, the charging power represented by the single-energy storage device power information is negative, and during discharging, the charging power represented by the single-energy storage device power information is positive.)

[0040] The third sub-step involves generating battery power information corresponding to each individual energy storage device based on the obtained power information of each individual energy storage device. In practice, the control terminal can determine the sum of the power of each individual energy storage device as represented by its power information as the battery power information corresponding to each individual battery energy storage device. This battery power information can represent the total power of each battery energy storage device during discharge or charging.

[0041] The fourth sub-step involves determining the dispatch power as the difference between the power represented by the battery power information and the demand power represented by the load power information. In practice, the dispatch power can be determined by subtracting the demand power represented by the load power information from the power represented by the battery power information.

[0042] The fifth sub-step involves adjusting the output power of the second three-phase inverter connected to the main grid to the main grid to the dispatch power in response to determining that the dispatch power is greater than zero, so as to feed power to the main grid.

[0043] In the sixth sub-step, in response to determining that the dispatch power is less than or equal to zero, the second three-phase inverter is controlled to absorb electrical energy from the main grid, and the output power of the second three-phase inverter flowing to the DC bus of the microgrid is adjusted to the absolute value of the dispatch power to supply power to the load.

[0044] In some optional implementations of certain embodiments, the control terminal 103 can control the charging or discharging of each battery energy storage device based on the photovoltaic power output information and the load power information through the following steps, so as to perform inter-grid and intra-grid hierarchical collaborative power dispatching:

[0045] The first step, in response to determining that the output power represented by the photovoltaic power generation output power information is greater than zero and the output power represented by the photovoltaic power generation output power information is less than the demand power represented by the load power information, is to perform the following steps:

[0046] The first sub-step involves controlling each of the aforementioned battery energy storage devices to discharge to the aforementioned DC bus.

[0047] The second sub-step involves collecting battery power information corresponding to each of the aforementioned battery energy storage devices. In practice, for each of the aforementioned battery energy storage devices, the following data collection steps are performed: First, energy storage voltage information is collected through the voltage sensors at the DC input / output terminals of the aforementioned battery energy storage devices, and energy storage current information is collected through the bidirectional current sensors at the DC input / output terminals of the aforementioned battery energy storage devices. Second, based on the aforementioned energy storage voltage information and energy storage current information, power information for a single energy storage device is generated. Finally, based on the obtained power information for each single energy storage device, battery power information corresponding to each of the aforementioned battery energy storage devices is generated.

[0048] The third sub-step involves generating a balanced power based on the aforementioned battery power information, photovoltaic power output information, and load power information. In practice, the sum of the power represented by the battery power information and the output power represented by the photovoltaic power output information can be determined as the first power. Then, the difference between the first power and the demand power represented by the load power information is determined as the balanced power.

[0049] In the fourth sub-step, in response to determining that the above-mentioned balanced power is greater than zero, the output power of the second three-phase inverter connected to the above-mentioned main grid to the above-mentioned main grid is adjusted to the above-mentioned balanced power, so as to feed power to the above-mentioned main grid.

[0050] The fifth sub-step involves adjusting the second three-phase inverter to absorb power from the main grid and adjusting the output power of the second three-phase inverter to the DC bus of the microgrid to the balanced power, in response to determining that the balanced power is less than or equal to zero.

[0051] In some optional implementations of certain embodiments, the control terminal 103 is further configured to control the charging or discharging of each battery energy storage device based on the photovoltaic power output information and the load power information, so as to perform inter-grid and intra-grid hierarchical collaborative power dispatching processing:

[0052] The first step, in response to determining that the output power represented by the photovoltaic power generation output power information is greater than zero and that the output power represented by the photovoltaic power generation output power information is greater than the demand power represented by the load power information, is to perform the following steps:

[0053] The first sub-step is to determine the difference between the output power represented by the photovoltaic power generation output power information and the demand power represented by the load power information as the power to be stored corresponding to each of the battery energy storage devices.

[0054] The second sub-step involves collecting the state of charge (SOC) information for each of the aforementioned battery energy storage devices. Each SOC information corresponds to one of the aforementioned battery energy storage devices, and the SOC information includes battery availability.

[0055] The third sub-step involves generating the upper limit energy storage power based on the aforementioned state-of-charge (POC) information. In practice, the average of the availability rates of each battery included in the POC information can be determined as the overall battery availability rate. Then, the control unit can obtain the total rated capacity corresponding to each of the aforementioned battery energy storage devices. Finally, the product of the overall battery availability rate and the total rated capacity can be determined as the upper limit energy storage power.

[0056] The fourth sub-step involves determining, in response to the determination that the power to be stored is less than or equal to the upper limit of energy storage power, at least one battery availability rate among the battery availability rates included in each of the aforementioned state of charge information is less than a preset battery availability rate. The preset battery availability rate can be 90%.

[0057] The fifth sub-step involves sorting the availability of at least one battery in ascending order to obtain a battery availability sequence.

[0058] The sixth sub-step, based on the battery availability sequence and the power to be stored, performs the following allocation process:

[0059] In sub-step one, for the first battery availability rate in the battery availability rate sequence, based on the aforementioned battery availability rate and the preset total battery capacity, the storable power corresponding to the first battery availability rate is generated. In practice, the control terminal can determine the storable power by multiplying the battery availability rate by the preset total battery capacity. The preset total battery capacity can be the rated capacity of the battery energy storage device.

[0060] Sub-step two: Determine the difference between the power to be stored and the power that can be stored as the target value.

[0061] Sub-step three: In response to the target value being greater than zero, the target value is determined as the power to be stored, and the power to be stored is updated.

[0062] Sub-step four involves removing the first battery availability from the battery availability sequence to update the battery availability sequence.

[0063] The seventh sub-step involves performing the above allocation process again based on the updated battery availability sequence and the updated power to be stored.

[0064] The eighth sub-step, in response to the target value being less than or equal to zero, determines at least one storable power as at least one allocated storage power.

[0065] The ninth sub-step involves controlling at least one of the battery energy storage devices to charge based on the aforementioned at least one allocated storage power. In practice, for each of the aforementioned at least one allocated storage power, the control terminal can control the corresponding battery energy storage device in at least one battery energy storage device to continuously absorb electricity at the rate of the allocated storage power.

[0066] The tenth sub-step involves generating a feed power based on the power to be stored and the upper limit energy storage power, in response to determining that the power to be stored is greater than the upper limit energy storage power. In practice, the difference between the power to be stored and the upper limit energy storage power can be determined as the feed power.

[0067] The eleventh sub-step involves adjusting the output power of the second three-phase inverter connected to the main grid to the main grid to the aforementioned feed power, so as to feed power to the main grid.

[0068] The above-described technical solution and its related content, as an inventive point of this disclosure, solve the technical problem that "when the photovoltaic power generation exceeds the power required by the load, the excess electrical energy needs to be stored in various battery energy storage devices. However, directly storing the excess power evenly in each battery energy storage device can cause some of the devices to overcharge, leading to faster aging of the battery energy storage devices." The factors that accelerate the aging of battery energy storage devices are often as follows: when the photovoltaic power generation exceeds the power required by the load, the excess electrical energy needs to be stored in various battery energy storage devices. However, directly storing the excess power evenly in each battery energy storage device can cause some of the devices to overcharge, leading to faster aging of the battery energy storage devices. Solving these factors can slow down the aging process of battery energy storage devices. To achieve this effect, firstly, in response to determining that the output power represented by the photovoltaic power generation output power information is greater than zero and that the output power represented by the photovoltaic power generation output power information is greater than the demand power represented by the load power information, the following steps are performed: First, the difference between the output power represented by the photovoltaic power generation output power information and the demand power represented by the load power information is determined as the power to be stored corresponding to each of the battery energy storage devices. Thus, the power to be stored can be obtained. Then, the state of charge (SOC) information of each of the battery energy storage devices is collected, wherein each SOC information corresponds to one of the battery energy storage devices, and the SOC information includes battery availability. Next, based on the SOC information, an upper limit energy storage power is generated. Thus, the maximum power that each battery energy storage device can currently safely store, i.e., the upper limit energy storage power, can be obtained. Then, in response to determining that the power to be stored is less than or equal to the upper limit energy storage power, at least one battery availability rate among the battery availability rates included in the SOC information that is less than a preset battery availability rate is determined. Therefore, when the power to be stored is less than or equal to the upper limit of energy storage power, at least one battery availability rate corresponding to at least one battery energy storage device with a lower stored capacity can be determined. Then, the at least one battery availability rate is sorted in ascending order to obtain a battery availability rate sequence. This yields a battery availability rate sequence for allocation processing. Next, based on the battery availability rate sequence and the power to be stored, the following allocation processing is performed: First, for the first battery availability rate in the battery availability rate sequence, based on the battery availability rate and the preset total battery capacity, a storable power corresponding to the first battery availability rate is generated. Second, the difference between the power to be stored and the storable power is determined as a target value. Third, in response to the target value being greater than zero, the target value is determined as the power to be stored, thus updating the power to be stored. Fourth, the first battery availability rate is deleted from the battery availability rate sequence to update the battery availability rate sequence.Subsequently, based on the updated battery availability sequence and the updated power to be stored, the above allocation process is executed again. Then, in response to the target value being less than or equal to zero, at least one storable power is determined as at least one allocated storage power. Thus, through the above allocation process, allocation is performed one by one according to the power to be stored and the availability of each battery, ensuring priority is given to battery storage devices with lower storage capacity, and charging allocation is performed in ascending order, resulting in at least one allocated storage power corresponding to at least one rechargeable battery storage device with a low storage capacity. Based on the at least one allocated storage power, at least one of the battery storage devices is controlled to charge. Thus, at least one rechargeable battery storage device with a low storage capacity can be charged according to at least one allocated storage power, reducing the risk of overcharging. In response to determining that the power to be stored is greater than the upper limit storage power, a feed power is generated based on the power to be stored and the upper limit storage power. The output power of the second three-phase inverter connected to the main grid is adjusted to the feed power to feed power to the main grid. Therefore, when the power to be stored exceeds the upper limit of energy storage power, the excess portion can be output to the main grid as power feeder, further reducing the overcharging phenomenon of battery energy storage equipment and thus slowing down the aging rate of battery energy storage equipment.

[0069] Third, in response to determining the fault detection information of the main power grid, indicating that a fault has occurred in the main power grid, the microgrid's power dispatching process is executed.

[0070] In some optional implementations of certain embodiments, the control terminal 103 is further configured to perform microgrid power dispatch in response to determining that main grid fault detection information indicates a fault has occurred in the main grid by the following steps:

[0071] The first step, in response to determining that the main grid fault detection information indicates a fault in the main grid, involves collecting the photovoltaic power output information of each photovoltaic power generation device, the load power information of each load end, and the overall state of charge information of each battery energy storage device. The overall state of charge information includes the overall battery availability rate. The load ends include each preset priority load device and each preset non-priority load device. Each preset non-priority load device includes at least one variable frequency speed control load device and at least one constant load device.

[0072] The second step involves performing the following load shedding control process in response to the determination that the output power represented by the photovoltaic power generation output power information is less than the demand power represented by the load power information and the overall battery availability is less than the first preset overall battery availability:

[0073] The first sub-step involves controlling the shutdown of each of the aforementioned preset non-priority load devices, and after shutting down each preset non-priority load device, again collecting the output power of the first three-phase inverter output side connected to the aforementioned load terminals as the target output power. The aforementioned first preset overall battery availability rate can be 10%.

[0074] The second sub-step, in response to determining that the target output power is greater than the output power represented by the photovoltaic power generation output power information, involves sending a power reduction command to the inverter built into each of the at least one variable frequency drive (VFD) load devices to reduce the power demand of the VFD load device. The power reduction command can indicate the degree of power reduction; for example, the power reduction command could be "command":"reduce_power", "value_kW":10", indicating a power reduction of 10kW.

[0075] The third step is to control each of the battery energy storage devices to discharge to the DC bus in response to the determination that the output power represented by the photovoltaic power generation output power information is less than the demand power represented by the load power information and the overall battery availability is greater than the first preset overall battery availability.

[0076] The above-described technical solution and its related content, as an inventive point of this disclosure, solve the technical problem of "increased probability of microgrid collapse". Factors leading to an increased probability of microgrid collapse often include: when the main grid fails, if the photovoltaic power output is insufficient to cover the load demand, and the battery energy storage devices are unable to fully compensate for the shortfall due to low state of charge, and the system does not initiate demand response measures such as non-critical load reduction or variable frequency speed regulation, the microgrid will face a continuous power shortage. At this time, critical loads may shut down due to insufficient power supply. If the voltage / frequency continuously deviates from the safety threshold, it can easily trigger microgrid collapse, increasing the probability of microgrid collapse. Solving these factors can reduce the probability of microgrid collapse. To achieve this effect, firstly, the photovoltaic power output information of each photovoltaic power generation device, the load power information of the load end, and the overall state of charge information of each battery energy storage device are collected. The overall state of charge information includes the overall battery availability rate. The load side includes each preset priority load device and each preset non-priority load device. Each preset non-priority load device includes at least one variable frequency speed control load device and at least one constant load device. Then, in response to determining that the output power represented by the photovoltaic power generation output power information is less than the demand power represented by the load power information and the overall battery availability rate is less than the first preset overall battery availability rate, the following load reduction control process is executed: First, the preset non-priority load devices are shut down. After shutting down the preset non-priority load devices, the output power of the first three-phase inverter connected to the load side is collected again as the target output power. Thus, when the output power represented by the photovoltaic power generation output power information is less than the demand power represented by the load power information and the overall battery availability rate is less than the first preset overall battery availability rate (i.e., the photovoltaic power generation output power is insufficient to cover the load demand at the load side), and each battery energy storage device has an excessively low state of charge, the non-priority load devices are shut down. By reducing the non-priority load, the pressure on the microgrid is alleviated, thereby reducing the risk of microgrid collapse. Furthermore, after shutting down the non-priority load devices, the target output power is collected again. Next, in response to determining that the target output power is greater than the output power represented by the photovoltaic power generation output power information, for each of the at least one variable frequency drive (VFD) load devices, a power reduction command is sent to the inverter built into the VFD load device to reduce the power demand of the VFD load device. Thus, even when the target output power is still greater than the photovoltaic power generation, a power reduction command can be sent to the VFD load device to further reduce load demand, thereby lowering the probability of microgrid failure.Finally, in response to the determination that the output power represented by the photovoltaic power generation output power information is less than the demand power represented by the load power information and the overall battery availability is greater than the first preset overall battery availability, the battery energy storage devices are controlled to discharge to the DC bus. Thus, the battery energy storage devices can be activated to discharge to the DC bus to supplement the power gap when the overall battery availability is greater than the first preset overall battery availability, i.e., the battery availability is still sufficient.

[0077] In some optional implementations of certain embodiments, the control terminal 103 is further configured to perform microgrid power dispatching processing in response to determining main grid fault detection information indicating a main grid fault:

[0078] The first step, in response to the determination that the main grid fault detection information indicates a fault in the main grid, involves collecting the photovoltaic power output information of each photovoltaic power generation device, the load power information of each load end, and the overall state of charge information of each battery energy storage device. The overall state of charge information includes the overall battery availability. The load ends include each preset priority load device and each preset non-priority load device. The preset non-priority load devices include at least one variable frequency speed control load device and at least one constant load device.

[0079] The second step involves controlling at least one of the battery energy storage devices to discharge to the DC bus to supply power to the load, in response to determining that the output power represented by the photovoltaic power generation output power information is zero and the overall battery availability rate is greater than a first preset overall battery availability rate. In practice, the control unit can estimate the SOC value of each battery energy storage device as the battery availability rate of each battery energy storage device using a state observer. Then, the average of the battery availability rates can be determined as the overall battery availability rate of each battery energy storage device. In response to determining that the overall battery availability rate is greater than a preset value (e.g., 40%), the control unit can determine at least one battery availability rate greater than a preset availability rate threshold as at least one screened battery availability rate. Then, the execution entity can determine the sum of the at least one screened battery availability rate as a first value. Then, for each of the at least one screened battery availability rates, the execution entity can determine the ratio of the screened battery availability rate to the first value as a second value. Then, the execution entity can determine the product of the second value and the electrical power represented by the load power information as the output power. Next, the aforementioned executing entity can control the output of each battery energy storage device corresponding to the selected battery availability rate, and the output power corresponding to the desired output power. The aforementioned first preset overall battery availability rate can be defined as the ratio of the remaining available power of the battery energy storage device to the total battery capacity in a microgrid system reaching this set threshold, indicating that the battery energy storage device has sufficient power to support discharge.

[0080] In some optional implementations of certain embodiments, the control terminal 103 is further configured to perform microgrid power dispatching processing in response to determining main grid fault detection information indicating a main grid fault:

[0081] The first step involves controlling at least one of the battery energy storage devices to charge, in response to the determination that the output power represented by the photovoltaic power generation output power information is greater than the demand power represented by the load power information and the overall battery availability rate is less than a second preset overall battery availability rate. The second preset overall battery availability rate refers to the rate at which the system will initiate charging of the battery energy storage devices when the available power (i.e., the ratio of remaining usable battery capacity to total capacity) of the battery energy storage devices falls below this set value in the microgrid system. In practice, the control unit can determine the storable power as the difference between the output power represented by the photovoltaic power generation output power information and the demand power represented by the load power information. Then, the execution entity collects the state-of-charge (SOC) information of each of the battery energy storage devices. Based on the SOC information and the storable power, at least one allocated storage power corresponding to at least one of the battery energy storage devices is generated. Finally, charging of at least one of the battery energy storage devices is controlled based on the at least one allocated storage power.

[0082] The second step involves implementing curtailment control in response to the determination that the output power represented by the photovoltaic power generation output power information is greater than the demand power represented by the load power information and the overall battery availability is greater than the second preset overall battery availability:

[0083] The first sub-step involves controlling at least one of the aforementioned battery energy storage devices to stop charging.

[0084] The second sub-step involves generating energy loss power information based on the aforementioned photovoltaic power generation output power information and load power information. In practice, the control unit can determine the energy loss power information as the difference between the output power represented by the photovoltaic power generation output power information and the power represented by the load power information.

[0085] The third sub-step involves controlling the output power of each photovoltaic power generation device to the power value represented by the load power information, based on the aforementioned energy loss power information. In practice, firstly, the executing entity can determine the output power information of each individual power generation device corresponding to each photovoltaic power generation device. Then, a dynamic programming algorithm is used to select at least one individual power generation device output power information that represents the power value and is equal to the power value represented by the aforementioned energy loss power information from the individual power generation device output power information. Afterward, the control terminal can control at least one individual power generation device corresponding to the at least one individual power generation device output power information to shut down.

[0086] Figure 2 A flowchart 200 illustrates some embodiments of a power dispatching method according to the present disclosure, which applies the control terminal included in the power dispatching system described above. The power dispatching method includes the following steps:

[0087] Step 201: Perform fault detection processing on the main power grid to obtain main power grid fault detection information.

[0088] In some embodiments, the power dispatching execution entity (e.g., the control terminal included in the power dispatching system) can perform fault detection processing on the main power grid to obtain main power grid fault detection information.

[0089] Step 202: In response to the determination that the main grid fault detection information indicates that no fault has occurred in the main grid, the following grid-connected power dispatching process is performed:

[0090] Step 2021: Collect photovoltaic power output information and load power information of each photovoltaic power generation device and the load end.

[0091] In some embodiments, the execution entity may collect photovoltaic power output information of each of the photovoltaic power generation devices and load power information of the load end.

[0092] Step 2022: Based on the photovoltaic power output information and load power information, control the charging or discharging of each battery energy storage device to perform inter-grid and intra-grid hierarchical collaborative power dispatch processing.

[0093] In some embodiments, the aforementioned execution entity may control the charging or discharging of each battery energy storage device based on the aforementioned photovoltaic power output information and the aforementioned load power information, so as to perform inter-grid and intra-grid hierarchical collaborative power dispatch processing.

[0094] Step 203: In response to determining that the main grid fault detection information indicates that a fault has occurred in the main grid, perform power dispatch processing within the microgrid.

[0095] In some embodiments, the aforementioned execution entity may perform power dispatching processing within the microgrid in response to determining that fault detection information in the main grid indicates a fault in the main grid.

[0096] The various embodiments disclosed above have the following beneficial effects: the power dispatch system of some embodiments of this disclosure reduces energy waste or supply-demand mismatch and improves energy utilization efficiency. Specifically, the reasons for energy waste, supply-demand mismatch, and low energy utilization efficiency are as follows: setting a fixed power threshold to determine the power interaction between the microgrid and the main grid simply involves transmitting excess power from the microgrid exceeding the upper limit to the main grid, or obtaining power from the main grid to meet the load demand within the microgrid when photovoltaic power supply is insufficient (when photovoltaic power generation is below a preset lower limit). This does not consider the impact of energy storage device charging or discharging on power dispatch, nor can it reasonably supplement power based on the actual situation of photovoltaic power generation and load power consumption within the microgrid, leading to increased energy waste or supply-demand mismatch and low energy utilization efficiency. Based on this, some embodiments of the power dispatch system disclosed herein include: a control terminal, a microgrid, and a main grid, wherein: the microgrid includes various photovoltaic power generation devices, various battery energy storage devices, and a load terminal; the various photovoltaic power generation devices and the various battery energy storage devices are connected to a DC bus via DC-side coupling; the load terminal is connected to the DC bus via a first three-phase inverter; and the DC bus is connected to the main grid via a second three-phase inverter. Thus, independent control of intra-grid and inter-grid energy flow can be achieved through dual inverters (the first three-phase inverter is connected to the load, and the second three-phase inverter is connected to the main grid). The control terminal is configured to perform the following control steps: perform fault detection processing on the main grid to obtain main grid fault detection information. Thus, fault detection can be performed on the main grid to generate main grid fault detection information for determining whether to perform grid-connected power dispatch processing or microgrid-based power dispatch processing. Subsequently, in response to the confirmation that the main grid fault detection information indicates no fault has occurred in the main grid, the following grid-connected power dispatching process is executed: Photovoltaic power output information of each photovoltaic power generation device and load power information of the load terminals are collected. This allows for the collection of photovoltaic power output and load power information. Then, based on this photovoltaic power output and load power information, the charging or discharging of each battery energy storage device is controlled to perform hierarchical coordinated power dispatching between and within the grid. Thus, based on the collected photovoltaic power output and load power information, priority can be given to controlling each battery energy storage device to store excess electricity or supply power to the load terminals to supplement load gaps. Controlling the charging and discharging of energy storage devices avoids simply sending excess power into the main grid or relying solely on the main grid when photovoltaic power generation is insufficient. Energy storage devices provide a buffer for the microgrid; regulating the charging and discharging of energy storage devices solves problems such as energy storage not participating in dispatching decisions and supply-demand matching lag in traditional power dispatching. Power is stored when photovoltaic power generation is excessive and released when photovoltaic power generation is insufficient.After each battery energy storage device is charged or discharged, hierarchical collaborative power dispatching between and within the grid is performed, taking into account the impact of the charging or discharging status of the energy storage devices on power dispatching. In response to the determination of main grid fault detection information indicating a main grid fault, power dispatching within the microgrid is executed. Therefore, when a main grid fault occurs, the microgrid can maintain independent operation and automatically adjust power flow according to photovoltaic power generation and load demand. In this way, even if the main grid cannot supply power normally, the microgrid can still ensure stable power supply through intelligent dispatching, avoiding power outages. Furthermore, the use of DC-coupled dual inverters (the first three-phase inverter connects to the load, and the second three-phase inverter connects to the main grid) enables independent control of energy flow between and within the grid, allowing the microgrid to automatically switch between grid-connected (hierarchical collaborative power dispatching between and within the grid) or off-grid mode (power dispatching within the microgrid) based on the main grid fault status. Furthermore, based on the collected photovoltaic power output and load power information, the charging and discharging behavior of the battery energy storage equipment is dynamically controlled. The energy storage is used to prioritize the balance of supply and demand within the grid (charging when there is excess photovoltaic power and discharging when there is insufficient power). This reduces energy waste caused by "simply sending out excess power" or "over-reliance on the main grid", ensures stable system operation, and improves the efficiency of power dispatch and energy utilization.

[0097] The above description is merely a selection of preferred embodiments of this disclosure and an explanation of the technical principles employed. Those skilled in the art should understand that the scope of the invention involved in the embodiments of this disclosure is not limited to technical solutions formed by specific combinations of technical features, but should also cover other technical solutions formed by arbitrary combinations of technical features or their equivalents without departing from the inventive concept. For example, technical solutions formed by substituting features with (but not limited to) technical features with similar functions disclosed in the embodiments of this disclosure.

Claims

1. A power dispatching system, comprising: The control terminal, microgrid, and main grid, among which: The microgrid includes various photovoltaic power generation devices, various battery energy storage devices, and load terminals; Each photovoltaic power generation device and each battery energy storage device are connected to the DC bus via DC-side coupling. The load end is connected to the DC bus via a first three-phase inverter, and the DC bus is connected to the main power grid via a second three-phase inverter. The control terminal is configured to perform the following control steps: The main power grid is subjected to fault detection processing to obtain main power grid fault detection information; In response to the determination that the main grid fault detection information indicates that no fault has occurred in the main grid, the following grid-connected power dispatching procedures are performed: Collect the photovoltaic power output information of each photovoltaic power generation device and the load power information of the load end; Based on the photovoltaic power output information and the load power information, the charging or discharging of each battery energy storage device is controlled to perform inter-grid and intra-grid hierarchical collaborative power dispatching. In response to determining that the main grid fault detection information indicates a fault has occurred in the main grid, power dispatch processing within the microgrid is performed.

2. The power dispatching system according to claim 1, wherein, The control terminal is further configured to: For each of the aforementioned photovoltaic power generation devices, the following data collection steps are performed: Photovoltaic output voltage information is collected by a voltage sensor at the DC output terminal of the photovoltaic power generation equipment, and photovoltaic output current information is collected by a current sensor at the DC output terminal of the photovoltaic power generation equipment. Based on the photovoltaic output voltage information and the photovoltaic output current information, the output power information of a single power generation device is generated; Based on the obtained output power information of each individual power generation device, photovoltaic power generation output power information corresponding to each photovoltaic power generation device is generated. The three-phase power information of the output side of the first three-phase inverter connected to the load terminal is collected as the load power information.

3. The power dispatching system according to claim 1, wherein, The control terminal is further configured to perform the following steps: In response to the determination that the output power represented by the photovoltaic power generation output power information is equal to zero, the scheduling process under the no-photovoltaic-output condition is executed: Control each battery energy storage device to discharge to the DC bus; For each of the battery energy storage devices, perform the following data collection steps: Energy storage voltage information is collected through the voltage sensor at the DC input / output terminal of the battery energy storage device, and energy storage current information is collected through the bidirectional current sensor at the DC input / output terminal of the battery energy storage device. Based on the energy storage voltage information and the energy storage current information, power information for a single energy storage device is generated. Based on the obtained power information of each individual energy storage device, battery power information corresponding to each battery energy storage device is generated. The difference between the power represented by the battery power information and the demand power represented by the load power information is determined as the scheduling power; In response to determining that the dispatch power is greater than zero, the output power of the second three-phase inverter connected to the main grid flowing to the main grid is adjusted to the dispatch power, so as to feed power to the main grid; In response to determining that the dispatch power is less than or equal to zero, the second three-phase inverter is controlled to absorb electrical energy from the main grid, and the output power of the second three-phase inverter flowing to the DC bus of the microgrid is adjusted to the absolute value of the dispatch power to supply power to the load.

4. The power dispatching system according to claim 1, wherein, The control terminal is further configured to: In response to determining that the output power represented by the photovoltaic power generation output power information is greater than zero and the output power represented by the photovoltaic power generation output power information is less than the demand power represented by the load power information, the following steps are performed: Control each battery energy storage device to discharge to the DC bus; Collect battery power information corresponding to each of the battery energy storage devices; Based on the battery power information, the photovoltaic power output power information, and the load power information, a balanced power is generated; In response to determining that the balanced power is greater than zero, the output power of the second three-phase inverter connected to the main grid to the main grid is adjusted to the balanced power, so as to feed power to the main grid; In response to determining that the balanced power is less than or equal to zero, the second three-phase inverter is adjusted to absorb power from the main grid, and the output power of the second three-phase inverter to the DC bus of the microgrid is adjusted to the balanced power.

5. The power dispatching system according to claim 1, wherein, The control terminal is further configured to: In response to determining that the main grid fault detection information indicates that a fault has occurred in the main grid, the photovoltaic power output information of each photovoltaic power generation device, the load power information of the load end, and the overall state of charge information of each battery energy storage device are collected. The overall state of charge information includes the overall battery availability. The load end includes each preset priority load device and each preset non-priority load device. Each preset non-priority load device includes at least one variable frequency speed control load device and at least one constant load device. In response to determining that the output power represented by the photovoltaic power generation output power information is equal to zero and the overall battery availability is greater than a first preset overall battery availability, at least one of the battery energy storage devices is controlled to discharge to the DC bus to supply power to the load.

6. The power dispatching system according to claim 5, wherein, The photovoltaic power generation devices in each of the photovoltaic power generation devices are connected in parallel, and the control terminal is further configured to: In response to determining that the output power represented by the photovoltaic power generation output power information is greater than the demand power represented by the load power information and the overall battery availability is less than the second preset overall battery availability, at least one of the battery energy storage devices is controlled to charge. In response to the determination that the output power represented by the photovoltaic power generation output power information is greater than the demand power represented by the load power information and the overall battery availability is greater than the second preset overall battery availability, the following curtailment control process is performed: Control at least one of the battery energy storage devices to stop charging; Based on the photovoltaic power output information and the load power information, energy loss power information is generated; Based on the energy loss power information, the output power of each photovoltaic power generation device is controlled to be the power value represented by the load power information.

7. A power dispatching method, applied to the control terminal of the power dispatching system according to any one of claims 1-6, the method comprising: The main power grid is subjected to fault detection processing to obtain main power grid fault detection information; In response to the determination that the main grid fault detection information indicates that no fault has occurred in the main grid, the following grid-connected power dispatching procedures are performed: Collect the photovoltaic power output information of each photovoltaic power generation device and the load power information of the load end; Based on the photovoltaic power output information and the load power information, the charging or discharging of each battery energy storage device is controlled to perform inter-grid and intra-grid hierarchical collaborative power dispatching. In response to determining that the main grid fault detection information indicates a fault has occurred in the main grid, power dispatch processing within the microgrid is performed.

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