Power distribution network hierarchical coordination control method and device, medium, equipment and product

Abstract

The invention discloses a hierarchical coordination control method and device for a power distribution network, a medium, equipment and a product. The method comprises the steps that state information of the flexible interconnected power distribution network is acquired and judged, the flexible interconnected power distribution network comprises a plurality of areas, and the frequency deviation of each area is the same; in response to the fact that the flexible interconnection power distribution network is in a normal operation state, flexible interconnection devices in the area are controlled to operate based on the layered direct current droop control strategy; otherwise, the flexible interconnection device is controlled to operate based on the constant-voltage and constant-frequency control strategy. When the operation of the flexible interconnection device is controlled, a frequency deviation amplitude limiting link is arranged to ensure the stable operation of the power distribution network. Through state judgment and a control strategy of the corresponding flexible interconnection device, switching between a layered direct current droop control strategy and a constant voltage and constant frequency control strategy is carried out, an automatic coordination control technology of the flexible interconnection power distribution network with frequency deviation is introduced, the influence of the frequency deviation on operation of the power distribution network is improved, and the power distribution network performance is improved. And the automatic coordination control of the frequency deviation is realized.

Description

Technical Field

[0001] The present invention relates to a distribution network hierarchical coordinated control method, device, medium, equipment and product, and belongs to the technical field of distribution network hierarchical coordinated control. Background Art

[0002] Flexible interconnected distribution network is an important part of modern smart grid. It has high flexibility and adaptability, and can realize efficient integration and optimized dispatch of multiple energy sources. However, with the large-scale access of distributed energy, the frequency stability of distribution network faces severe challenges. Distributed energy, such as photovoltaic power generation and wind power generation, has the characteristics of unstable output and strong volatility, which makes it difficult for traditional distribution network control methods to deal with frequency deviation problems.

[0003] Frequency deviation not only affects the quality of power, but may also trigger a chain reaction, endangering the overall safety and reliability of the power grid. Frequency stability is crucial to the normal operation of the power system, as it is directly related to the normal operation of power equipment and the safety of users' electricity use. When the grid frequency deviates from the rated value, it may cause equipment overheating, reduced efficiency, and even cause large-scale power outages. Summary of the invention

[0004] The purpose of the present invention is to overcome the deficiencies in the prior art and provide a distribution network hierarchical coordinated control method, device, medium, equipment and product. Based on a flexible interconnected distribution network, through state judgment and the control strategy of the corresponding flexible interconnected device, the hierarchical DC droop control strategy and the constant voltage and frequency control strategy are switched, and the automatic coordinated control technology of the flexible interconnected distribution network with frequency deviation is introduced, which improves the influence of frequency deviation on the operation of the distribution network and realizes the automatic coordinated control of frequency deviation.

[0005] To achieve the above object, the present invention is implemented by adopting the following technical solutions:

[0006] In a first aspect, the present invention discloses a distribution network hierarchical coordinated control method, the hierarchical coordinated control method comprising the following steps:

[0007] Acquire and determine the status information of a flexible interconnected distribution network; wherein the flexible interconnected distribution network includes a plurality of asynchronous flexible interconnected areas, and the flexible interconnected devices in different areas are connected through medium voltage DC feeders; when a power disturbance occurs in any area, all areas jointly respond to the power disturbance and the frequency deviation of each area is the same;

[0008] In response to the flexible interconnected distribution network being in a normal operating state, issuing a first control instruction based on a hierarchical DC droop control strategy to control the operation of the flexible interconnected devices in the area;

[0009] In response to the flexible interconnected distribution network being in a system fault state, issuing a second control instruction based on a constant voltage and constant frequency control strategy to control the operation of the flexible interconnected device;

[0010] Wherein, when controlling the operation of the flexible interconnection device, a frequency deviation limiting link is provided to ensure the stable operation of the distribution network.

[0011] Furthermore, the flexible interconnected distribution network includes an AC bus and a plurality of regions connected to the AC bus, and the flexible interconnected devices in different regions are connected through a medium voltage DC feeder to achieve asynchronous flexible interconnection between regions;

[0012] Each area includes a flexible interconnection device, a distribution transformer and a low-voltage DC microgrid; the flexible interconnection device is connected to the AC bus through a medium-voltage single-phase AC port and a distribution transformer; the flexible interconnection device is connected to the low-voltage DC microgrid through a low-voltage DC port, and the low-voltage DC microgrid includes a DC bus, and a charging pile, an energy storage unit and a photovoltaic power generation unit connected to the DC bus.

[0013] Furthermore, the hierarchical DC droop control strategy includes:

[0014] Obtaining a DC voltage reference value of the DC bus;

[0015] Calculating the compensation voltage value based on a two-layer control strategy of low bandwidth communication technology;

[0016] According to the DC voltage reference value, the compensation voltage value is superimposed, and the current inner loop reference value is calculated through Clarke transformation and proportional integral regulator to ensure that errors are eliminated and thus achieve zero static error regulation.

[0017] Furthermore, the expression of the current inner loop reference value is as follows:

[0018]

[0019] In the formula, Indicates the current inner loop reference value; represents the proportional gain of the current regulator; Indicates the DC voltage reference value; Indicates the compensation voltage value; represents the integral gain of the current regulator; Indicates the integral symbol; represents the integral over time t.

[0020] Furthermore, the expression of the DC voltage reference value is as follows:

[0021]

[0022] In the formula, Indicates the DC voltage reference value; Indicates the DC voltage rating; represents virtual impedance; Indicates direct current; represents the power disturbance value of the i-th region;

[0023] The expression of the compensation voltage value is as follows:

[0024]

[0025] In the formula, Indicates the compensation voltage value; Indicates DC voltage; Represents the controller proportional coefficient; Represents the controller integral coefficient; represents a complex variable; represents the power disturbance value of the ith region.

[0026] Furthermore, the expression of the power disturbance value of the i-th region is as follows:

[0027]

[0028] In the formula, represents the power disturbance value of the i-th region; represents the unit frequency regulation power of the ith region combined with the frequency characteristics of the generator and the load; Represents the frequency deviation of the distribution network system, , represents the frequency response of the distribution network system, and n represents the number of regions.

[0029] Furthermore, the hierarchical coordinated control method further comprises the following steps:

[0030] In response to the flexible interconnected distribution network being in a normal operating state, a third control instruction is issued based on a maximum power point tracking control strategy to control the photovoltaic power generation unit to work, until the battery SOC value of the energy storage unit reaches an upper limit, the maximum power point tracking control strategy is switched to a layered DC droop control strategy to issue a fourth control instruction to control the photovoltaic power generation unit to work, thereby reducing the output power of the photovoltaic power generation unit;

[0031] When controlling the operation of the photovoltaic power generation unit, a current limiting link is provided to ensure the stable operation of the distribution network. The current limiting link includes a current upper limit I max and the current lower limit I min .

[0032] Furthermore, the maximum power point tracking control strategy includes adjusting the operating voltage and current of the photovoltaic array of the photovoltaic power generation unit so that the output power of the photovoltaic power generation unit reaches a maximum value.

[0033] In a second aspect, the present invention discloses a distribution network hierarchical coordination control device, comprising:

[0034] A data acquisition module is used to acquire and determine the status information of a flexible interconnected distribution network; wherein the flexible interconnected distribution network includes a plurality of asynchronous flexible interconnected areas, and the flexible interconnected devices in different areas are connected through medium-voltage DC feeders; when a power disturbance occurs in any area, all areas respond to the power disturbance together and the frequency deviation of each area is the same;

[0035] A normal operation module, configured to issue a first control instruction based on a hierarchical DC droop control strategy to control the operation of the flexible interconnection device in response to the flexible interconnection distribution network being in a normal operation state;

[0036] A system fault module, configured to issue a second control instruction based on a constant voltage and constant frequency control strategy to control the operation of the flexible interconnection device in response to the flexible interconnection distribution network being in a system fault state;

[0037] Wherein, when controlling the operation of the flexible interconnection device, a frequency deviation limiting link is provided to ensure the stable operation of the distribution network.

[0038] Furthermore, the flexible interconnected distribution network includes an AC bus and a plurality of regions connected to the AC bus, and the flexible interconnected devices in different regions are connected through a medium voltage DC feeder to achieve asynchronous flexible interconnection between regions;

[0039] Each area includes a flexible interconnection device, a distribution transformer and a low-voltage DC microgrid; the flexible interconnection device is connected to the AC bus through a medium-voltage single-phase AC port and a distribution transformer; the flexible interconnection device is connected to the low-voltage DC microgrid through a low-voltage DC port, and the low-voltage DC microgrid includes a DC bus, and a charging pile, an energy storage unit and a photovoltaic power generation unit connected to the DC bus.

[0040] In a third aspect, the present invention discloses a computer-readable storage medium having a computer program / instruction stored thereon. When the computer program / instruction is executed by a processor, the steps of the above-mentioned distribution network hierarchical coordinated control method are implemented.

[0041] In a fourth aspect, the present invention discloses a computer device, comprising:

[0042] Memory, for storing computer programs / instructions;

[0043] A processor is used to execute the computer program / instructions to implement the steps of the above-mentioned distribution network hierarchical coordinated control method.

[0044] In a fifth aspect, the present invention discloses a computer program product, including a computer program / instruction, which implements the steps of the above-mentioned distribution network hierarchical coordinated control method when executed by a processor.

[0045] Compared with the prior art, the present invention has the following beneficial effects:

[0046] The present invention is based on a flexible interconnected distribution network. Through state judgment and the control strategy of the corresponding flexible interconnected device, the layered DC droop control strategy and the constant voltage and frequency control strategy are switched, and the automatic coordination control technology of the flexible interconnected distribution network with frequency deviation is introduced, which improves the influence of frequency deviation on the operation of the distribution network and realizes the automatic coordination control of frequency deviation. The frequency deviation and the power deviation of the interconnecting line are significantly reduced, and the operation reliability and economy of the distribution network are improved. This research not only has a breakthrough in technology, but also shows broad application prospects and value, and provides an important reference for the optimization of future distribution networks. BRIEF DESCRIPTION OF THE DRAWINGS

[0047] Figure 1 is a flow chart of the distribution network hierarchical coordinated control method provided in Example 1;

[0048] Figure 2 is a structural schematic diagram of the flexible interconnected distribution network provided in Example 1;

[0049] Figure 3 is a schematic diagram of the control strategy provided in Example 1;

[0050] Figure 4 is a comparison diagram of output power in region 1 provided in Example 1;

[0051] Figure 5 is a comparison diagram of output power in region 2 provided in Example 1;

[0052] Figure 6 is a frequency deviation comparison diagram provided in Example 1;

[0053] Figure 7 This is a comparison diagram of the tie line power deviation provided in Example 1. DETAILED DESCRIPTION

[0054] The present invention will be further described below in conjunction with the accompanying drawings. The following embodiments are only used to more clearly illustrate the technical solution of the present invention, and cannot be used to limit the protection scope of the present invention.

[0055] Example 1

[0056] This embodiment 1 provides a distribution network hierarchical coordinated control method, such as Figure 1 As shown, the following steps are included:

[0057] Obtain and determine the status information of the flexible interconnected distribution network; wherein the flexible interconnected distribution network includes multiple asynchronous flexible interconnected areas, and the flexible interconnected devices in different areas are connected through medium-voltage DC feeders; when a power disturbance occurs in any area, all areas respond to the power disturbance together and the frequency deviation of each area is the same;

[0058] In response to the flexible interconnected distribution network being in a normal operating state, a first control instruction is issued based on a hierarchical DC droop control strategy to control the operation of the flexible interconnected devices in the area;

[0059] In response to the flexible interconnected distribution network being in a system fault state, a second control instruction is issued based on a constant voltage and constant frequency control strategy to control the operation of the flexible interconnected device;

[0060] Among them, when controlling the operation of the flexible interconnection device, a frequency deviation limiting link is provided to ensure the stable operation of the distribution network.

[0061] The technical concept of the present invention is: based on the flexible interconnected distribution network, through state judgment and the control strategy of the corresponding flexible interconnected device, the layered DC droop control strategy and the constant voltage and frequency control strategy are switched, and the automatic coordination control technology of the flexible interconnected distribution network with frequency deviation is introduced to improve the impact of frequency deviation on the operation of the distribution network and realize the automatic coordination control of frequency deviation. The frequency deviation and the power deviation of the interconnecting line are significantly reduced, and the operating reliability and economy of the distribution network are improved. This research not only has a breakthrough in technology, but also shows broad application prospects and value, providing an important reference for the optimization of future distribution networks.

[0062] The design idea of ​​the distribution network hierarchical coordinated control method in this embodiment is as follows:

[0063] (1) Flexible interconnected distribution network.

[0064] like Figure 2 The figure shows the flexible interconnected distribution network involved in this embodiment, and its structure and frequency characteristics are first analyzed.

[0065] After the flexible interconnection of regions, the flexible interconnected distribution network may face problems such as excessive short-circuit current and simultaneous commutation failure of multiple DC lines in the receiving-end power grid. Using the back-to-back technology of the flexible interconnected distribution network, the receiving-end power grid can be divided into multiple asynchronous interconnected areas. The flexible interconnected distribution network includes an AC bus and multiple areas connected to the AC bus. The flexible interconnected devices in different areas are connected through medium-voltage DC feeders to achieve asynchronous flexible interconnection between regions.

[0066] Each area includes a flexible interconnection device, a distribution transformer and a low-voltage DC microgrid; the flexible interconnection device is connected to the AC bus through a medium-voltage single-phase AC port and a distribution transformer; the flexible interconnection device is connected to the low-voltage DC microgrid through a low-voltage DC port. The low-voltage DC microgrid includes a DC bus, and charging piles, energy storage units and photovoltaic power generation units connected to the DC bus.

[0067] The system uses an AC feeder with a voltage level of 20kV, which can meet the capacity requirements of the existing 10kV and 20kV AC distribution networks and adapt to the further increase in the capacity of the DC distribution network in the future.

[0068] When the regional power system is in a steady state, the grids connected to each port are actively controlled to evenly distribute the energy differences between the two regional distribution networks through medium-voltage DC feeders. Distributed micro-energy nodes in the region can form a "chain" or "ring" through low-voltage DC microgrids to exchange energy and optimize power flow within or between regions.

[0069] like Figure 2 As shown, the flexible interconnected distribution network in this embodiment assumes that there are two areas, namely area 1 and area 2. When the load in area 1 suddenly increases or the AC power supply is insufficient, resulting in a power supply gap in the area, assuming that the transmission power between the areas remains unchanged, for area 1 of the flexible interconnected distribution network, its frequency change can be expressed as:

[0070] ;

[0071] In the formula, represents the power disturbance value of area 1; It represents the unit frequency regulation power of the frequency characteristics of the combined generator and load in area 1; Indicates the frequency deviation of region 1;

[0072] If the various regions of the flexible interconnected distribution network do not support each other, after a power disturbance occurs in a certain region, the frequency of the region will have a large frequency deviation, affecting the frequency stability of the region. Therefore, it is necessary to quickly adjust the back-to-back power of the flexible interconnected distribution network to make the frequencies of each region equal, that is, after the power disturbance, all regions of the flexible interconnected distribution network respond to the power disturbance together like a "synchronous network". At this time, the frequency response can be expressed as:

[0073] ;

[0074] In the formula, represents the frequency response of the distribution network system, It represents the unit frequency regulation power of the frequency characteristics of the generator and the load in area 2; Indicates the frequency deviation of region 2.

[0075] Ideally, the frequency response of the flexible interconnected distribution network is that the frequency of each area is the same, so that the frequency of each area of ​​the flexible interconnected distribution network is the same, and the frequency deviation of each area is:

[0076] ;

[0077] In the formula, Indicates the frequency deviation of the distribution network system.

[0078] According to the above two formulas, we can calculate

[0079] ;

[0080] Assume there are n regions, , Represents the frequency deviation of the distribution network system, represents the frequency response of the distribution network system, and n represents the number of regions.

[0081] Then, the power disturbance value borne by region i is expressed as:

[0082] ;

[0083] During the operation of the flexible interconnected distribution network, once a power disturbance occurs in area 1, the active power increment urgently transmitted from area 2 to area 1 is expressed as:

[0084] ;

[0085] In the formula, It represents the increase of active power transmitted from area j to area i.

[0086] (2) Control strategy of flexible interconnected devices.

[0087] like Figure 3 As shown in the figure, the control strategy of the flexible interconnection device mainly includes hierarchical DC droop control strategy, constant voltage and frequency control strategy and current limiting control strategy. During normal operation, the system adopts hierarchical DC droop control strategy to suppress the influence of inconsistent line impedance by increasing virtual impedance. When a three-phase short circuit occurs, it switches to the constant voltage and frequency control strategy. The specific steps are as follows:

[0088] In response to the flexible interconnected distribution network being in a normal operating state, a first control instruction is issued based on the hierarchical DC droop control strategy to control the operation of the flexible interconnected devices in the control area. The control equation is:

[0089] ;

[0090] In the formula, Indicates the DC voltage reference value; Indicates the DC voltage rating; represents virtual impedance; Indicates direct current; represents the power disturbance value of the ith region.

[0091] Due to the different line impedances between interconnected devices, the output voltages at each end of the flexible interconnected distribution network are different. This effect is usually suppressed by adding virtual impedance. In order to compensate for the voltage drop, a two-layer control strategy based on low-bandwidth communication technology is adopted, and its compensation voltage is:

[0092] ;

[0093] In the formula, Indicates the compensation voltage value; Indicates the DC voltage rating; Indicates DC voltage; Represents the controller proportional coefficient; Represents the controller integral coefficient; represents a complex variable; represents the power disturbance value of the ith region.

[0094] The DC voltage reference value is obtained by superimposing the compensation voltage value on the hierarchical DC droop control strategy, and the voltage reference value is subtracted from the feedback value to obtain the current inner loop reference value I* αβ through the proportional integral regulator. The specific process can be expressed by the following formula:

[0095] ;

[0096] In the formula, Indicates the current inner loop reference value; represents the proportional gain of the current regulator; Indicates the DC voltage reference value; Indicates the compensation voltage value; represents the integral gain of the current regulator; Indicates the integral symbol; represents the integral over time t.

[0097] The current inner loop adopts the control strategy in the αβ coordinate system. Specifically, the αβ coordinate system simplifies the control process by converting the three-phase current signal into two stationary components (α axis and β axis). This conversion process utilizes the Clarke transformation, making current control in the stationary coordinate system more direct and efficient. Using the proportional and integral combination of the proportional-integral regulator, the system can eliminate the error to zero when reaching steady state, ensuring that the output is stable near the target value, thereby achieving zero static error regulation.

[0098] In response to the flexible interconnected distribution network being in a system fault state, a second control instruction is issued based on a constant voltage and constant frequency control strategy to control the operation of the flexible interconnected device. Specifically, constant voltage and constant frequency control is adopted in the αβ coordinate system, the AC voltage reference value is set to a two-phase sinusoidal quantity, and a proportional integral regulator is also used to achieve zero static error regulation.

[0099] In order to ensure the stability of the flexible interconnection device during the switching process of different control strategies, an upper limit of f is added in the control link. max The lower limit is f min The frequency deviation limiting link is implemented to avoid equipment shutdown caused by overcurrent triggering the protection link during the switching process.

[0100] (2) Control strategy of photovoltaic power generation unit.

[0101] In response to the flexible interconnected distribution network being in normal operation, a third control instruction is issued based on the maximum power point tracking control strategy to control the operation of the photovoltaic power generation unit, and the output power of the system under the current environmental conditions is maximized by adjusting the operating voltage and current of the photovoltaic array of the photovoltaic power generation unit. The controller continuously adjusts the operating point and compares the power changes before and after the adjustment to find the maximum power point.

[0102] When the battery SOC value of the energy storage unit reaches the upper limit, the maximum power point tracking control strategy is switched to the layered DC droop control strategy to issue a fourth control instruction to control the operation of the photovoltaic power generation unit, thereby reducing the output power of the photovoltaic power generation unit;

[0103] Among them, in order to prevent the output current from exceeding the limit, when controlling the operation of the photovoltaic power generation unit, a current limiting link is set to ensure the stable operation of the distribution network. The current limiting link includes the current upper limit I max and the current lower limit I min .

[0104] According to the above content of the present invention, by using MATLAB simulation software, the following is established: Figure 2 The simulation model of the 10kV flexible interconnected distribution network is shown in Figure 1, and the main parameters of the system are shown in Table 1.

[0105] Table 1 System related parameters

[0106]

[0107] Set the system to change the load at 0.4s, 1.0s and 1.2s. The simulation results are as follows Figure 4 and Figure 5The results show that the proposed method can achieve balanced distribution of power between regions, reduce energy consumption in the power supply process, and improve the reliability and economy of power supply. Under load interference conditions, this method can effectively control the load frequency of the two regions in the flexible interconnected distribution network and significantly reduce the frequency deviation and tie line power deviation.

[0108] Through simulation analysis within 0-0.4s, the system can absorb the surplus power in the microgrid through the low-voltage DC port in area 1 and supply power to the load, while ensuring the power required for the operation of the low-voltage DC grid. Within the range of 0.4-0.8s, the power load in area 1 began to rise, and the system began to have a power gap of 5MW. At this time, the power supply network in area 2 began to provide balanced power to area 1 through the medium-voltage DC interconnection distribution system.

[0109] In the range of 0.8-1.2s, the power load in area 1 still has a power gap of about 2.5MW, and the distribution network in area 2 continues to output the same power to area 1, effectively filling the power gap during the operation of the microgrid.

[0110] In the range of 1.2-1.6s, there is a power gap of 2.5MW in the power load of area 2. Area 1 exports power to area 2 through the network to ensure the balanced distribution of power in the system.

[0111] The simulation analysis results show that the flexible interconnected medium-voltage DC distribution coordinated control technology can achieve balanced power distribution according to the power conditions of each port, reduce energy consumption in the power supply process, and improve the reliability and economy of power supply.

[0112] The technology in this paper is used to perform automatic coordinated control in interconnected distribution networks in different areas, count the load frequency control effects in different areas, and count the output frequency deviation.

[0113] The statistical results are as follows Figure 6 As shown in the experimental results, it can be seen that the use of this technology to automatically coordinate and control the flexible interconnected distribution network can effectively reduce the frequency deviation of different areas in the flexible interconnected distribution network and stabilize the frequency deviation of the flexible interconnected distribution network within an ideal range.

[0114] The change of the power deviation of the tie line in the flexible interconnected distribution network is as follows: Figure 7 As shown. The experimental results show that before the method in this paper is used for automatic coordinated control, the frequency deviation fluctuation range of the two areas in the flexible interconnected distribution network is large; after the method in this paper is used for automatic coordinated control, the frequency deviation fluctuation range of the two areas is significantly reduced. The experimental results prove that this technology can automatically coordinate and control the frequency deviation of the flexible interconnected distribution network and reduce the frequency deviation and tie line power deviation of the flexible interconnected distribution network.

[0115] The present invention discusses the automatic coordination control technology of a flexible interconnected distribution network based on frequency deviation. By constructing a flexible interconnected distribution network and using the control strategy of a flexible interconnected device and a photovoltaic power generation system, the automatic coordination control of frequency deviation is achieved.

[0116] The present invention takes into account the frequency deviation problem that the system may face in actual operation, transforms it into a comprehensive control process, and verifies the effectiveness of the technology through experiments. The results show that the present invention significantly reduces the frequency deviation and tie line power deviation, improves the operational reliability and economy of the system, and thus shows significant advantages in improving the system utilization efficiency and competitive advantage in the power market.

[0117] Example 2

[0118] This embodiment 2 provides a distribution network hierarchical coordination control device, including:

[0119] A data acquisition module is used to acquire and determine the status information of the flexible interconnected distribution network; wherein the flexible interconnected distribution network includes multiple asynchronous flexible interconnected areas, and the flexible interconnected devices in different areas are connected through medium-voltage DC feeders; when a power disturbance occurs in any area, all areas respond to the power disturbance together and the frequency deviation of each area is the same;

[0120] A normal operation module, configured to issue a first control instruction based on a hierarchical DC droop control strategy to control the operation of the flexible interconnection device in response to the flexible interconnection distribution network being in a normal operation state;

[0121] A system fault module, configured to issue a second control instruction based on a constant voltage and constant frequency control strategy to control the operation of the flexible interconnection device in response to the flexible interconnection distribution network being in a system fault state;

[0122] Among them, when controlling the operation of the flexible interconnection device, a frequency deviation limiting link is provided to ensure the stable operation of the distribution network.

[0123] Furthermore, the flexible interconnected distribution network includes an AC bus and a plurality of regions connected to the AC bus, and the flexible interconnected devices in different regions are connected via a medium voltage DC feeder to achieve asynchronous flexible interconnection between regions;

[0124] Each area includes a flexible interconnection device, a distribution transformer and a low-voltage DC microgrid; the flexible interconnection device is connected to the AC bus through a medium-voltage single-phase AC port and a distribution transformer; the flexible interconnection device is connected to the low-voltage DC microgrid through a low-voltage DC port. The low-voltage DC microgrid includes a DC bus, and charging piles, energy storage units and photovoltaic power generation units connected to the DC bus.

[0125] Example 3

[0126] This embodiment 3 provides a computer-readable storage medium on which a computer program / instruction is stored. When the computer program / instruction is executed by a processor, the steps of the distribution network hierarchical coordinated control method of embodiment 1 are implemented.

[0127] Example 4

[0128] This embodiment 4 provides a computer device, including:

[0129] Memory, for storing computer programs / instructions;

[0130] A processor is used to execute computer programs / instructions to implement the steps of the distribution network hierarchical coordinated control method of Example 1.

[0131] Example 5

[0132] This embodiment 5 provides a computer program product, including a computer program / instruction, which implements the steps of the distribution network hierarchical coordinated control method of embodiment 1 when executed by a processor.

[0133] Those skilled in the art will appreciate that the embodiments of the present application may be provided as methods, systems, or computer program products. Therefore, the present application may adopt the form of a complete hardware embodiment, a complete software embodiment, or an embodiment combining software and hardware. Moreover, the present application may adopt the form of a computer program product implemented on one or more computer-usable storage media (including but not limited to disk storage, CD-ROM, optical storage, etc.) containing computer-usable program codes.

[0134] The present application is described with reference to the flowcharts and / or block diagrams of the methods, devices (systems), and computer program products according to the embodiments of the present application. It should be understood that each process and / or box in the flowchart and / or block diagram, as well as the combination of the processes and / or boxes in the flowchart and / or block diagram, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, a special-purpose computer, an embedded processor, or other programmable data processing device to generate a machine, so that the instructions executed by the processor of the computer or other programmable data processing device generate instructions for implementing the processes in the flowchart and / or block diagram. Figure 1 A process or multiple processes and / or boxes Figure 1 A device that provides the functions specified in a block or multiple blocks.

[0135] These computer program instructions may also be stored in a computer-readable memory capable of directing a computer or other programmable data processing device to operate in a specific manner, so that the instructions stored in the computer-readable memory produce an article of manufacture comprising an instruction device, which implements the process Figure 1 A process or multiple processes and / or boxes Figure 1 A function specified in one or more boxes.

[0136] These computer program instructions can also be loaded onto a computer or other programmable data processing device so that a series of operating steps are executed on the computer or other programmable device to produce a computer-implemented process, thereby providing instructions for implementing the process. Figure 1 A process or multiple processes and / or boxes Figure 1 The steps for the functions specified in one or more boxes.

[0137] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principle of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. A hierarchical coordinated control method for distribution network, characterized in that: The hierarchical coordinated control method comprises the following steps: Acquire and determine the status information of a flexible interconnected distribution network; wherein the flexible interconnected distribution network includes a plurality of asynchronous flexible interconnected areas, and the flexible interconnected devices in different areas are connected through medium voltage DC feeders; when a power disturbance occurs in any area, all areas jointly respond to the power disturbance and the frequency deviation of each area is the same; In response to the flexible interconnected distribution network being in a normal operating state, issuing a first control instruction based on a hierarchical DC droop control strategy to control the operation of the flexible interconnected devices in the area; In response to the flexible interconnected distribution network being in a system fault state, issuing a second control instruction based on a constant voltage and constant frequency control strategy to control the operation of the flexible interconnected device; Wherein, when controlling the operation of the flexible interconnection device, a frequency deviation limiting link is provided to ensure the stable operation of the distribution network.

2. The distribution network hierarchical coordinated control method according to claim 1 is characterized in that: The flexible interconnected distribution network includes an AC bus and multiple areas connected to the AC bus, and the flexible interconnected devices in different areas are connected through medium-voltage DC feeders to achieve asynchronous flexible interconnection between areas; Each area includes a flexible interconnection device, a distribution transformer and a low-voltage DC microgrid; the flexible interconnection device is connected to the AC bus through a medium-voltage single-phase AC port and a distribution transformer; the flexible interconnection device is connected to the low-voltage DC microgrid through a low-voltage DC port, and the low-voltage DC microgrid includes a DC bus, and a charging pile, an energy storage unit and a photovoltaic power generation unit connected to the DC bus.

3. The distribution network hierarchical coordinated control method according to claim 2 is characterized in that: The hierarchical DC droop control strategy includes: Obtaining a DC voltage reference value of the DC bus; Calculating the compensation voltage value based on a two-layer control strategy of low-bandwidth communication technology; According to the DC voltage reference value, the compensation voltage value is superimposed, and the current inner loop reference value is calculated through Clarke transformation and proportional integral regulator to ensure that errors are eliminated and thus achieve zero static error regulation.

4. The distribution network hierarchical coordinated control method according to claim 3 is characterized in that: The expression of the current inner loop reference value is as follows: ； In the formula, Indicates the current inner loop reference value; represents the proportional gain of the current regulator; Indicates the DC voltage reference value; Indicates the compensation voltage value; represents the integral gain of the current regulator; represents the integral symbol; represents the integral over time t.

5. The distribution network hierarchical coordinated control method according to claim 4 is characterized in that: The expression of the DC voltage reference value is as follows: ； In the formula, Indicates the DC voltage reference value; Indicates the DC voltage rating; represents virtual impedance; Indicates direct current; represents the power disturbance value of the i-th region; The expression of the compensation voltage value is as follows: ； In the formula, Indicates the compensation voltage value; Indicates DC voltage; Represents the controller proportional coefficient; Represents the controller integral coefficient; represents a complex variable; represents the power disturbance value of the ith region.

6. The distribution network hierarchical coordinated control method according to claim 5 is characterized in that: The expression of the power disturbance value of the i-th region is as follows: ； In the formula, represents the power disturbance value of the i-th region; represents the unit frequency regulation power of the ith region combined with the frequency characteristics of the generator and the load; Represents the frequency deviation of the distribution network system, , represents the frequency response of the distribution network system, and n represents the number of regions.

7. The distribution network hierarchical coordinated control method according to claim 2 is characterized in that: The hierarchical coordinated control method further comprises the following steps: In response to the flexible interconnected distribution network being in a normal operating state, a third control instruction is issued based on a maximum power point tracking control strategy to control the photovoltaic power generation unit to work, until the battery SOC value of the energy storage unit reaches an upper limit, the maximum power point tracking control strategy is switched to a layered DC droop control strategy to issue a fourth control instruction to control the photovoltaic power generation unit to work, thereby reducing the output power of the photovoltaic power generation unit; When controlling the operation of the photovoltaic power generation unit, a current limiting link is provided to ensure the stable operation of the distribution network. The current limiting link includes a current upper limit I max and the current lower limit I min .

8. The distribution network hierarchical coordinated control method according to claim 7 is characterized in that: The maximum power point tracking control strategy includes adjusting the operating voltage and current of the photovoltaic array of the photovoltaic power generation unit so that the output power of the photovoltaic power generation unit reaches a maximum value.

9. A distribution network hierarchical coordination control device, characterized in that: include: A data acquisition module is used to acquire and determine the status information of a flexible interconnected distribution network; wherein the flexible interconnected distribution network includes a plurality of asynchronous flexible interconnected areas, and the flexible interconnected devices in different areas are connected through medium-voltage DC feeders; when a power disturbance occurs in any area, all areas respond to the power disturbance together and the frequency deviation of each area is the same; A normal operation module, configured to issue a first control instruction based on a hierarchical DC droop control strategy to control the operation of the flexible interconnection device in response to the flexible interconnection distribution network being in a normal operation state; A system fault module, configured to issue a second control instruction based on a constant voltage and constant frequency control strategy to control the operation of the flexible interconnection device in response to the flexible interconnection distribution network being in a system fault state; Wherein, when controlling the operation of the flexible interconnection device, a frequency deviation limiting link is provided to ensure the stable operation of the distribution network.

10. The distribution network hierarchical coordination control device according to claim 9, characterized in that: The flexible interconnected distribution network includes an AC bus and multiple areas connected to the AC bus, and the flexible interconnected devices in different areas are connected through medium-voltage DC feeders to achieve asynchronous flexible interconnection between areas; Each area includes a flexible interconnection device, a distribution transformer and a low-voltage DC microgrid; the flexible interconnection device is connected to the AC bus through a medium-voltage single-phase AC port and a distribution transformer; the flexible interconnection device is connected to the low-voltage DC microgrid through a low-voltage DC port, and the low-voltage DC microgrid includes a DC bus, and a charging pile, an energy storage unit and a photovoltaic power generation unit connected to the DC bus.

11. A computer-readable storage medium having a computer program / instruction stored thereon, characterized in that: When the computer program / instruction is executed by a processor, the steps of the distribution network hierarchical coordinated control method described in any one of claims 1-8 are implemented.

12. A computer device, comprising: Memory, for storing computer programs / instructions; A processor is used to execute the computer program / instructions to implement the steps of the distribution network hierarchical coordinated control method according to any one of claims 1-8.

13. A computer program product comprising a computer program / instructions, characterized in that When the computer program / instruction is executed by a processor, the steps of the distribution network hierarchical coordinated control method described in any one of claims 1-8 are implemented.

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