Economical sagging-free control method based on distribution area energy storage system

Abstract

This invention proposes an economical, droop-free control strategy for distribution substation energy storage systems. It includes a communication module, a voltage compensation module, a minimum cost module, and a voltage-current dual-loop control module. In the communication module, a dynamic diffusion algorithm is used to obtain the required average value information by exchanging information with adjacent communication nodes. The voltage-current dual-loop control module ensures circuit accuracy. In the voltage compensation module, an integrator dynamically adjusts the DC bus reference voltage and output voltage of each energy storage unit, ultimately maintaining the DC bus voltage near the reference value. In the minimum cost module, an integrator dynamically adjusts the incremental cost of each energy storage unit and the average incremental cost of the energy storage system, ensuring that the incremental costs of each energy storage unit are consistent, thus minimizing power generation costs.

Description

Technical Field

[0001] This invention relates to the field of distributed energy storage system technology for DC microgrids, and in particular to an economical droop-free control strategy based on a distribution area energy storage system. Background Technology

[0002] The integration of numerous distributed renewable energy generation devices has led to instability and loss of controllability in the power output of the distribution network. Furthermore, the energy efficiency of energy storage systems is affected by multiple factors, including system scale, operating conditions, and environmental conditions, and is also related to the dynamic performance degradation characteristics of various components such as energy storage batteries and converters. Distribution transformer substations, as a primary means of optimizing distribution network operation, can provide stable and reliable strategies under normal conditions and rapid self-healing under fault conditions. However, the static voltage deviation in distribution transformer substations prevents distributed generator units from operating at their optimal point in real time. Therefore, voltage regulation and economic costs need to be adjusted modularly to eliminate the bus voltage deviation problem in real time and minimize the total generation cost as much as possible. Summary of the Invention

[0003] In view of the defects and shortcomings of the existing technology, the purpose of this invention is to provide an economical droop-free control strategy based on a distribution radio station energy storage system, and to provide a matching systematic design.

[0004] The present invention specifically adopts the following technical solution:

[0005] An economical droop-free control strategy based on a distribution area energy storage system includes the following steps:

[0006] At the beginning of each sampling period, the DC-side inductor current i Loi DC side output voltage V oi DC side output current i i Samples were taken separately;

[0007] Collect the equilibrium factor α of each energy storage unit in the energy storage system i and incremental cost λ i The average value α of the equilibrium factor of the energy storage system is obtained using the dynamic diffusion algorithm. avg and the average value of incremental cost λ avg ;

[0008] DC side output power P i Multiplying by the cost factor 2a, and then adding the result to the increment factor b, yields the incremental cost λ. i Then, the average incremental cost λ of the energy storage system avg Subtract the incremental cost λ of the energy storage unit i The minimum cost compensation amount δu is obtained through the integration process. λi, the minimum cost compensation amount δu λi The expression is as follows:

[0009] δu λi = ∫(λ avg - λ i )dt

[0010] Multiply the DC-side output current i i by the DC-side output voltage V oi to obtain the DC-side output power P i Then divide the DC-side output power P i by the maximum rated power P of the energy storage unit max Divide the obtained result by the gain z to get the process coefficient n. Subtract the process coefficient n from 1 to get the power factor Power factor<--0000131-->Multiply the power factor oi by the DC-side output voltage V i to obtain the balance factor α avg Divide the average value α of the balance factor by the power factor ref to obtain the balance voltage x. Then subtract the balance voltage x from the reference voltage V Vi After passing through the integral link, the voltage compensation amount δu Vi The expression is as follows:

[0011] <>

[0012] Add the introduced voltage compensation amount δu Vi , the minimum cost compensation amount δu λi and the DC-side output voltage reference value V ref , subtract the DC-side output voltage V oi and then pass through the voltage outer-loop PI controller G p (s) to obtain the DC-side reference current i refi , and then subtract it from the DC-side inductor current i of the local energy storage unit Loi and pass through the current inner-loop PI controller G e (s) to obtain the drive voltage V ki , and compare the drive voltage V ki with the triangular carrier wave to obtain the modulation signal.

[0013] Furthermore, the value range of the cost coefficient a is 0.01 < a < 1, and the value range of the increment coefficient b is 1 < b < 10.

[0014] Furthermore, the value range of the gain z is 0.1 < z < 1. <00001 kiFurthermore, an economical droop-free control system based on a distribution substation energy storage system includes a communication module, a voltage compensation module, a minimum cost module, and a voltage and current dual closed-loop control module. In the communication module, a dynamic diffusion algorithm is used to obtain the required average value information by exchanging information with adjacent communication nodes, ensuring the accuracy of the circuit in the voltage and current dual closed-loop control module. In the voltage compensation module, an integrator dynamically adjusts the magnitude of the DC bus reference voltage and output voltage of each energy storage unit, ultimately maintaining the DC bus voltage near the reference value. In the minimum cost module, an integrator dynamically adjusts the magnitude of the incremental cost of each energy storage unit and the average incremental cost of the energy storage system, ensuring that the incremental costs of each energy storage unit are consistent, thereby minimizing the power generation cost.

[0016] Furthermore, at the beginning of each sampling period, the DC-side inductor current i Loi DC side output voltage V oi DC side output current i i Based on separate sampling, the equalization factor α of each energy storage unit in the energy storage system is collected in the communication module. i and incremental cost λ i The average value α of the equilibrium factor of the energy storage system is obtained using the dynamic diffusion algorithm. avg and the average value of incremental cost λ avg .

[0017] Furthermore, in the minimum cost module, the DC side output power P i Multiplying by the cost factor 2a, and then adding the result to the increment factor b, yields the incremental cost λ. i Then, the average incremental cost λ of the energy storage system avg Subtract the incremental cost λ of the energy storage unit i The minimum cost compensation amount δu is obtained through the integration process. λi Minimum cost compensation δu λi The expression is:

[0018] δu λi =∫(λ) avg -λ i )dt.

[0019] Furthermore, in the voltage-current dual-loop control module, a voltage compensation amount δu will be introduced. Vi Minimum cost compensation δu λi and DC side output voltage reference value V ref Add them together, then subtract the DC-side output voltage V. oi Then it passes through the voltage outer loop PI controller G p (s) Obtain the DC side reference current i refi, and then subtracted from the inductor current i on the DC side of the local energy storage unit, and then passed through the current inner-loop PI controller G Loi (s) to obtain the drive voltage V e . The drive voltage V ki is then compared with the triangular carrier wave to obtain the modulation signal. ki

[0020] Further, the value range of the cost coefficient a is 0.01 < a < 1, the value range of the increment coefficient b is 1 < b < 10; the value range of the gain z is 0.1 < z < 1.

[0021] And, an electronic device includes a memory, a processor, and a computer program stored on the memory and executable on the processor. When the processor executes the program, the steps of the economic droop-free control strategy based on the distribution transformer area energy storage system described above are implemented.

[0022] A non-transitory computer-readable storage medium stores a computer program, characterized in that when the computer program is executed by a processor, the steps of the economic droop-free control strategy based on the distribution transformer area energy storage system described above are implemented.

[0023] Compared with the prior art, in the design of the present invention and its preferred solutions, in the communication layer module, by using the dynamic diffusion algorithm, the required average value information can be obtained by exchanging information with adjacent communication nodes. In the voltage-current double closed-loop control module, the accuracy of the circuit can be guaranteed. In the voltage compensation module, through an integrator, the DC bus reference voltage and the output voltage of each energy storage unit are dynamically adjusted, and finally the DC bus voltage is maintained near the reference value. In the minimum cost module, through an integrator, the average value of the incremental cost of each energy storage unit and the incremental cost of the energy storage system is dynamically adjusted, so that the incremental costs of each energy storage unit are consistent and the power generation cost is minimized. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] <00001​​​​​​​​​​​​​​​​​​​

[0029] In the following, specific embodiments of this application will be described in detail with reference to the accompanying drawings. Based on these detailed descriptions, those skilled in the art will be able to clearly understand and implement this application. Without departing from the principles of this application, features from various embodiments can be combined to obtain new implementations, or certain features from some embodiments can be substituted to obtain other preferred implementations.

[0030] It should be noted that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the exemplary embodiments according to this application. As used herein, the singular form is intended to include the plural form as well, unless the context clearly indicates otherwise. Furthermore, it should be understood that when the terms "comprising" and / or "including" are used in this specification, they indicate the presence of features, steps, operations, devices, components, and / or combinations thereof.

[0031] To make the features and advantages of this patent more apparent and understandable, specific embodiments are provided below for detailed explanation:

[0032] Figure 1 The diagram shown is the main circuit diagram of a power distribution area energy storage system in an application example provided by an embodiment of the present invention. It consists of four energy storage units connected in parallel via a DC-DC converter, where i = 1, 2, 3, 4, V. ref i is the reference value for bus voltage. i For DC-side output current, i Loi V is the DC-side inductor current. oi R is the DC-side output voltage. loadi R is the load resistance of each bus. linei R represents the line impedance corresponding to each energy storage unit. The line impedances of the four energy storage units are 0.1Ω, 0.2Ω, 0.3Ω, and 0.4Ω, respectively. i The line impedances between different energy storage units are 0.3Ω, 0.4Ω, 0.5Ω, and 0.6Ω, respectively.

[0033] Figure 2 The diagram shown is a control block diagram of an economical droop-free control strategy based on a distribution substation energy storage system according to an embodiment of the present invention. The implementation process of the scheme includes the following steps:

[0034] At the beginning of each sampling period, the DC-side inductor current i Loi DC side output voltage V oi DC side output current i i Samples were taken separately;

[0035] In the communication module, the balancing factor α of each energy storage unit in the energy storage system is collected. i and incremental cost λ i The average value α of the equilibrium factor of the energy storage system is obtained using the dynamic diffusion algorithm. avg and the average value of incremental cost λ avg ;

[0036] In the minimum cost module, the DC-side output power P i Multiplying by the cost factor 2a, and then adding the result to the increment factor b, yields the incremental cost λ. i Then, the average incremental cost λ of the energy storage system avg Subtract the incremental cost λ of the energy storage unit i The minimum cost compensation amount δu is obtained through the integration process. λi Minimum cost compensation δu λi The expression is:

[0037] δu λi =∫(λ) avg -λ i )dt

[0038] In the voltage compensation module, the DC side output current i i Multiply by the DC-side output voltage V oi The DC-side output power P is obtained. i Then the DC side output power P i Divide by the maximum rated power P of the energy storage unit max Dividing the result by the gain z yields the process coefficient n. Subtracting the process coefficient n from the coefficient 1 gives the power factor. Power Factor Multiply by the DC-side output voltage V oi Obtain the equilibrium factor α i The average value α of the equilibrium factor avg Divide by power factor Obtain the equilibrium voltage x, and then use the reference voltage V ref Subtracting the balance voltage x, and then integrating, we obtain the voltage compensation amount δu. Vi Voltage compensation amount δu Vi The expression is:

[0039]

[0040] In the voltage-current dual-loop control module, the introduced voltage compensation amount δu Vi Minimum cost compensation δu λi and DC side output voltage reference value V ref Add them together, then subtract the DC-side output voltage V. oi Then it passes through the voltage outer loop PI controller Gp (s) Obtain the DC side reference current i refi This is compared with the DC-side inductor current i of the local energy storage unit. Loi After subtraction, the current passes through the inner loop PI controller G. e (s) obtains the driving voltage V ki Drive voltage V ki The modulated signal is then obtained by comparing it with the triangular carrier wave.

[0041] Figure 3 The waveform diagram of incremental cost is shown. The strategy implemented by this invention can promote the rapid convergence of incremental costs of each energy storage unit, and the incremental costs of each energy storage unit can reach the same state in 0.1s.

[0042] Figure 4 The waveform diagram of the bus voltage is shown. When the strategy implemented in this invention is adopted, the bus voltage of each energy storage unit can be restored to the reference voltage of around 400V in 0.1s.

[0043] The embodiments of the present invention have been described in detail above with reference to the accompanying drawings, but the present invention is not limited to the described embodiments. For those skilled in the art, various changes, modifications, substitutions, and variations can be made to these embodiments without departing from the principles and spirit of the present invention, and these variations still fall within the protection scope of the present invention.

[0044] The system and method provided in this embodiment can be stored in a computer-readable storage medium in the form of code, implemented as a computer program, and the basic parameter information required for calculation can be input through computer hardware, and the calculation results can be output.

[0045] Those skilled in the art will understand that embodiments of the present invention can be provided as methods, systems, or computer program products. Therefore, the present invention can take the form of a completely hardware embodiment, a completely software embodiment, or an embodiment combining software and hardware aspects. Furthermore, the present invention can take the form of a computer program product embodied on one or more computer-usable storage media (including, but not limited to, disk storage, CD-ROM, optical storage, etc.) containing computer-usable program code.

[0046] This invention is described with reference to flowchart illustrations and / or block diagrams of methods, apparatus (systems), and computer program products according to embodiments of the invention. It will be understood that each block of the flowchart illustrations and / or block diagrams, and combinations of blocks in the flowchart illustrations and / or block diagrams, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, special-purpose computer, embedded processor, or other programmable data processing apparatus to produce a machine, such that the instructions, which execute via the processor of the computer or other programmable data processing apparatus, generate instructions for implementing the flowchart illustrations and / or block diagrams. Figure 1 One or more processes and / or boxes Figure 1 A device that provides the functions specified in one or more boxes.

[0047] These computer program instructions may also be stored in a computer-readable storage medium that can direct a computer or other programmable data processing device to function in a particular manner, such that the instructions stored in the computer-readable storage medium produce an article of manufacture including instruction means, which are implemented in a process Figure 1 One or more processes and / or boxes Figure 1 The function specified in one or more boxes.

[0048] These computer program instructions may also be loaded onto a computer or other programmable data processing equipment to cause a series of operational steps to be performed on the computer or other programmable equipment to produce a computer-implemented process, thereby providing instructions that execute on the computer or other programmable equipment for implementing the process. Figure 1 One or more processes and / or boxes Figure 1 The steps of the function specified in one or more boxes.

[0049] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and not to limit it. Although the present invention has been described in detail with reference to the above embodiments, those skilled in the art should understand that modifications or equivalent substitutions can still be made to the specific implementation of the present invention. Any modifications or equivalent substitutions that do not depart from the spirit and scope of the present invention should be covered within the scope of protection of the claims of the present invention.

[0050] This patent is not limited to the above-described preferred embodiment. Anyone can derive other forms of economical, droop-free control strategies based on distribution area energy storage systems under the guidance of this patent. All equivalent variations and modifications made within the scope of this patent application shall fall within the scope of this patent.

Claims

1. An economic droop - free control method based on a distribution transformer area energy storage system, characterized in that: It includes the following steps: At the beginning of each sampling period, the DC-side inductor current i Loi DC side output voltage V oi DC side output current i i Samples were taken separately; Collect the equilibrium factor α of each energy storage unit in the energy storage system i and incremental cost λ i The average value α of the equilibrium factor of the energy storage system is obtained using the dynamic diffusion algorithm. avg and the average value of incremental cost λ avg ; DC side output power P i Multiplying by the cost factor 2a, and then adding the result to the increment factor b, yields the incremental cost λ. i Then, the average incremental cost λ of the energy storage system avg Subtract the incremental cost λ of the energy storage unit i The minimum cost compensation amount δu is obtained through the integration process. λi Minimum cost compensation amount δu λi The expression is: you λi =∫(λ avg -l i )dt DC side output current i i Multiply by the DC-side output voltage V oi The DC-side output power P is obtained. i Then the DC side output power P i Divide by the maximum rated power P of the energy storage unit max Dividing the result by the gain z yields the process coefficient n. Subtracting the process coefficient n from the coefficient 1 gives the power factor. Power Factor Multiply by the DC-side output voltage V oi Obtain the equilibrium factor α i The average value α of the equilibrium factor avg Divide by power factor Obtain the equilibrium voltage x, and then use the reference voltage V ref Subtracting the balance voltage x, and then integrating, we obtain the voltage compensation amount δu. Vi Voltage compensation amount δu Vi The expression is: The introduced voltage compensation amount δu Vi Minimum cost compensation amount δu λi and DC side output voltage reference value V ref Add them together, then subtract the DC-side output voltage V. oi Then it passes through the voltage outer loop PI controller G p (s) Obtain the DC side reference current i refi Then, it is connected to the DC-side inductor current i of the local energy storage unit. Loi After subtraction, the current passes through the inner loop PI controller G. e (s) obtains the driving voltage V ki Drive voltage V ki The modulated signal is then obtained by comparing it with the triangular carrier wave. The value range of the cost coefficient a is 0.01 < a < 1, and the value range of the increment coefficient b is 1 < b < 10.

2. The economical droop-free control method based on a distribution substation energy storage system according to claim 1, characterized in that: The value range of the gain z is 0.1 < z < 1.

3. An economical droop-free control system based on a distribution substation energy storage system, used to implement the method as described in claim 1, characterized in that: It includes a communication module, a voltage compensation module, a minimum - cost module, and a voltage - current double - closed - loop control module; in the communication module, by using the dynamic diffusion algorithm, the required average - value information can be obtained by exchanging information with adjacent communication nodes, so as to ensure the accuracy of the circuit in the voltage - current double - closed - loop control module; in the voltage compensation module, the DC - bus reference voltage and the output voltage of each energy - storage unit are dynamically adjusted through an integrator, and finally the DC - bus voltage is maintained near the reference value; in the minimum - cost module, the increment cost of each energy - storage unit and the average value of the increment cost of the energy - storage system are dynamically adjusted through an integrator, so that the increment costs of each energy - storage unit are consistent to meet the minimum power - generation cost.

4. The economical droop-free control system based on a distribution substation energy storage system according to claim 3, characterized in that: At the beginning of each sampling period, the DC-side inductor current i Loi DC side output voltage V oi DC side output current i i Based on separate sampling, the equalization factor α of each energy storage unit in the energy storage system is collected in the communication module. i and incremental cost λ i The average value α of the equilibrium factor of the energy storage system is obtained using the dynamic diffusion algorithm. avg and the average value of incremental cost λ avg .

5. The economic droop - free control system based on a distribution transformer area energy storage system according to claim 4, characterized in that: In the minimum cost module, the DC side output power P i Multiplying by the cost factor 2a, and then adding the result to the increment factor b, yields the incremental cost λ. i Then, the average incremental cost λ of the energy storage system avg Subtract the incremental cost λ of the energy storage unit i The minimum cost compensation amount δu is obtained through the integration process. λi Minimum cost compensation amount δu λi The expression is: you λi =∫(λ avg -l i )dt.

6. The economical droop-free control system based on a distribution substation energy storage system according to claim 5, characterized in that: In the voltage and current dual closed-loop control module, the introduced voltage compensation amount δu Vi Minimum cost compensation amount δu λi and DC side output voltage reference value V ref Add them together, then subtract the DC-side output voltage V. oi Then it passes through the voltage outer loop PI controller G p (s) Obtain the DC side reference current i refi Then, it is connected to the DC-side inductor current i of the local energy storage unit. Loi After subtraction, the current passes through the inner loop PI controller G. e (s) obtains the driving voltage V ki Drive voltage V ki The modulated signal is then obtained by comparing it with the triangular carrier wave.

7. The economic droop - free control system based on a distribution transformer area energy storage system according to claim 6, characterized in that: The value range of the cost coefficient a is 0.01 < a < 1, and the value range of the increment coefficient b is 1 < b < 10; the value range of the gain z is 0.1 < z < 1.

8. An electronic device comprising a memory, a processor, and a computer program stored in the memory and executable on the processor, characterized in that, When the processor executes the program, it realizes the steps of the economic droop - free control method based on a distribution transformer area energy storage system as described in claim 1 or 2.

9. A non-transitory computer-readable storage medium having a computer program stored thereon, characterized in that, When the computer program is executed by the processor, it realizes the steps of the economic droop - free control method based on a distribution transformer area energy storage system as described in claim 1 or 2.

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