A method for determining simulation parameters of an aluminum electrolysis cell

Abstract

The application belongs to the technical field of power system simulation analysis, and discloses a method for determining simulation parameters of an electrolytic aluminum electrolytic cell, which comprises the following steps: applying disturbance to electrolytic current of the electrolytic cell, recording voltage and current data of the electrolytic cell, and performing per-unit processing; establishing a second-order system based on a dynamic process of the electrolytic cell; bringing the voltage and current disturbance change data into the second-order system to determine simulation parameters of the electrolytic cell. The application regards the dynamic process of the electrolytic cell as a response of a second-order system, and the simulation accuracy is greatly improved compared with the current method of using a voltage source and a resistor in series, which has a positive effect on improving accurate simulation of the electrolytic aluminum load.

Description

Technical Field

[0001] This invention relates to the technical field of power system simulation analysis, and in particular to a method for determining simulation parameters of an aluminum electrolytic cell. Background Technology

[0002] Power systems are complex systems, and their study often relies on computational simulation. When performing computer simulations of power systems, it is necessary to build models of each component and determine relevant parameters. Electricity load is a crucial component of the power system, and establishing an accurate electricity load model is a fundamental requirement for power system simulation. Electrolytic aluminum is a high-energy-consuming load, with its electricity consumption exceeding 20% ​​in some areas. To accurately simulate and analyze the power grid in these areas, accurate modeling of the electrolytic aluminum load is essential.

[0003] Electrolytic cells are the main power-consuming component of the electrolytic aluminum plant's load, typically consuming over 90% of the total power. Accurate simulation of these cells is therefore crucial for the overall load simulation of electrolytic aluminum plants. Currently, electrolytic cells are generally simulated using a voltage source connected in series with a resistor. However, comparisons with actual data show that existing simulation methods cannot accurately reflect the response characteristics of the electrolytic cells. Therefore, this patent proposes a novel electrolytic cell simulation method. Summary of the Invention

[0004] The purpose of this section is to outline some aspects of embodiments of the present invention and to briefly describe some preferred embodiments. Simplifications or omissions may be made in this section, as well as in the abstract and title of this application, to avoid obscuring the purpose of these documents; however, such simplifications or omissions should not be construed as limiting the scope of the invention.

[0005] In view of the aforementioned existing problems, the present invention is proposed.

[0006] Therefore, the technical problem solved by the present invention is that the prior art cannot accurately reflect the response characteristics of the electrolyzer.

[0007] To solve the above-mentioned technical problems, the present invention provides the following technical solution: a method for determining simulation parameters of an aluminum electrolytic cell, comprising:

[0008] The electrolytic current of the electrolytic cell is perturbed, the voltage and current data of the electrolytic cell are recorded, and then normalized.

[0009] A second-order system is established based on the dynamic process of the electrolyzer;

[0010] By inputting voltage and current disturbance change data into the second-order system, the simulation parameters of the electrolytic cell are determined.

[0011] As a preferred embodiment of the method for determining simulation parameters of an electrolytic aluminum cell according to the present invention, the electrolytic cell comprises:

[0012] Through the first resistor R AL1 Second resistor R AL2 respectively with the first inductor L Al1 Second inductor L Al2 The series branches are then connected in parallel and then connected to the voltage source E. Al An electrolytic cell is simulated by connecting them in series.

[0013] As a preferred embodiment of the method for determining simulation parameters of an electrolytic aluminum cell according to the present invention, wherein: the voltage data during disturbance is defined as U. dc,m The current data is I dc,m .

[0014] As a preferred embodiment of the method for determining simulation parameters of an electrolytic aluminum cell according to the present invention, the data after per-unit processing is represented as follows:

[0015]

[0016]

[0017] Among them, U N I N These are the rated operating voltage and rated operating current of the electrolytic cell, respectively.

[0018] As a preferred embodiment of the method for determining simulation parameters of an electrolytic aluminum cell according to the present invention, wherein: U is taken as... dc,p I dc,p The values ​​at the time step before the perturbation are denoted as U. dc,0 I dc,0 ;

[0019] Take U dc,p I dc,p The data after the disturbance time are respectively denoted as U dc,f I dc,f .

[0020] As a preferred embodiment of the method for determining simulation parameters of an electrolytic aluminum cell according to the present invention, the disturbance variation data is represented as follows:

[0021] ΔU dc =U dc,f -U dc,0

[0022] ΔI dc =I dc,f -I dc,0

[0023] As a preferred embodiment of the method for determining simulation parameters of an electrolytic aluminum cell according to the present invention, the second-order system is represented as:

[0024]

[0025] Wherein, K1, K2, T1, and T2 are system parameters.

[0026] As a preferred embodiment of the method for determining simulation parameters of an electrolytic aluminum cell according to the present invention, wherein: ΔU dc As the input X of the second-order system, with ΔI dc As the output Y of the second-order system, the parameters K1, K2, T1, and T2 are identified using a nonlinear square function with minimum variance, and their corresponding values ​​are obtained.

[0027] As a preferred embodiment of the method for determining simulation parameters of an electrolytic aluminum cell according to the present invention, the per-unit values ​​of each parameter of the electrolytic cell are expressed as follows:

[0028]

[0029]

[0030]

[0031]

[0032]

[0033] As a preferred embodiment of the method for determining simulation parameters of an electrolytic aluminum cell according to the present invention, wherein: the per-unit values ​​of each parameter of the electrolytic cell are converted into named values ​​to obtain R. Al1 Z N R Al2 Z N L Al1 Z N L Al2 Z N E Al U N ,in

[0034] Based on the connection relationship of the electrolytic cell components, the nominal values ​​are imported into the simulation software to simulate the dynamic characteristics of the electrolytic cell.

[0035] The beneficial effects of the present invention are as follows: The method for determining simulation parameters of an electrolytic aluminum cell provided by the present invention treats the dynamic process of the electrolytic cell as a second-order system response, which greatly improves the simulation accuracy compared with the current method of only using a voltage source and a resistor in series. This method has a positive effect on improving the accurate simulation of the load on electrolytic aluminum. Attached Figure Description

[0036] To more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings used in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort. Wherein:

[0037] Figure 1 This is a flowchart of the electrolytic cell simulation process for determining the simulation parameters of an electrolytic aluminum cell according to an embodiment of the present invention.

[0038] Figure 2 This is a circuit diagram of an electrolytic cell simulation circuit for a method of determining simulation parameters of an electrolytic aluminum cell according to an embodiment of the present invention.

[0039] Figure 3 The measured voltage diagram of the electrolytic cell is shown in the simulation parameter determination method for the electrolytic aluminum cell according to an embodiment of the present invention.

[0040] Figure 4 The measured current diagram of the electrolytic cell is shown in an embodiment of the method for determining simulation parameters of an electrolytic aluminum cell according to the present invention.

[0041] Figure 5 This is a comparison chart of the measured and simulated currents of an electrolytic aluminum cell, based on an embodiment of the present invention, for determining the simulation parameters of the electrolytic aluminum cell. Detailed Implementation

[0042] To make the above-mentioned objects, features, and advantages of the present invention more apparent and understandable, specific embodiments of the present invention will be described in detail below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of them. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort should fall within the protection scope of the present invention.

[0043] Many specific details are set forth in the following description in order to provide a full understanding of the invention. However, the invention may also be practiced in other ways different from those described herein, and those skilled in the art can make similar extensions without departing from the spirit of the invention. Therefore, the invention is not limited to the specific embodiments disclosed below.

[0044] Secondly, the term "one embodiment" or "embodiment" as used herein refers to a specific feature, structure, or characteristic that may be included in at least one implementation of the present invention. The phrase "in one embodiment" appearing in different places in this specification does not necessarily refer to the same embodiment, nor is it a single or selective embodiment that is mutually exclusive with other embodiments.

[0045] This invention is described in detail with reference to the schematic diagrams. When detailing the embodiments of this invention, for ease of explanation, the cross-sectional views illustrating the device structure may be partially enlarged, not adhering to the usual scale. Furthermore, the schematic diagrams are merely examples and should not be construed as limiting the scope of protection of this invention. In actual fabrication, the three-dimensional spatial dimensions of length, width, and depth should be included.

[0046] Furthermore, in the description of this invention, it should be noted that the terms "upper," "lower," "inner," and "outer," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. These terms are used solely for the convenience of describing the invention and for simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on the invention. In addition, the terms "first," "second," or "third" are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0047] Unless otherwise explicitly specified and limited, the terms "installation," "connection," and "joining" in this invention should be interpreted broadly. For example, they can refer to fixed connections, detachable connections, or integral connections; similarly, they can refer to mechanical connections, electrical connections, or direct connections, or indirect connections through an intermediate medium, or internal connections between two components. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0048] Example 1

[0049] Reference Figure 1 —2, is the first embodiment of the present invention, which provides a method for determining simulation parameters of an aluminum electrolytic cell, including:

[0050] S1: Apply a disturbance to the electrolytic current of the electrolytic cell, record the voltage and current data of the electrolytic cell, and perform per-unit processing;

[0051] Furthermore, the electrolytic cell includes a first resistor R AL1 Second resistor R AL2 respectively with the first inductor L Al1 Second inductor L Al2 The series branches are then connected in parallel and then connected to the voltage source E. Al An electrolytic cell is simulated by connecting them in series.

[0052] Furthermore, the voltage data during the disturbance is defined as U. dc,m The current data is I dc,m .

[0053] The data after standardization is represented as follows:

[0054]

[0055]

[0056] Among them, U N I N These are the rated operating voltage and rated operating current of the electrolytic cell, respectively.

[0057] Take U dc,p I dc,p The values ​​at the time step before the perturbation are denoted as U. dc,0 I dc,0 ;

[0058] Take U dc,p I dc,p The data after the disturbance time are respectively denoted as U dc,f I dc,f .

[0059] The disturbance change data is represented as follows:

[0060] ΔU dc =U dc,f -U dc,0

[0061] ΔI dc =I dc,f -I dc,0

[0062] S2: Establishing a second-order system based on the dynamic process of the electrolyzer;

[0063] Furthermore, a second-order system can be represented as:

[0064]

[0065] Wherein, K1, K2, T1, and T2 are system parameters.

[0066] S3: Input the voltage and current disturbance change data into the second-order system to determine the simulation parameters of the electrolytic cell.

[0067] Furthermore, with ΔU dc As the input X of the second-order system, with ΔI dc As the output Y of the second-order system, the parameters K1, K2, T1, and T2 are identified using a nonlinear square function with minimum variance, and their corresponding values ​​are obtained.

[0068] Furthermore, the per-unit values ​​of the various parameters of the electrolytic cell are expressed as follows:

[0069]

[0070]

[0071]

[0072]

[0073]

[0074] Furthermore, the per-unit values ​​of each parameter of the electrolytic cell are converted into named values ​​to obtain R. Al1 Z N R Al2 Z N L Al1 Z N L Al2 Z N E Al U N ,in

[0075] Based on the connection relationship of the electrolytic cell components, the nominal values ​​are imported into the simulation software to simulate the dynamic characteristics of the electrolytic cell.

[0076] Example 2

[0077] Reference Figure 3 —5, is an embodiment of the present invention, which provides a method for determining simulation parameters of an electrolytic aluminum cell. In order to prove the beneficial effects of the present invention, specific experimental data are used for scientific demonstration.

[0078] In this embodiment, the rated voltage U of the electrolytic cell in the aluminum electrolytic plant is... N 1297V, rated current I N The current was 500kA. Adjusted via the aluminum electrolysis control system, the electrolytic cell current increased from 479kA to 489kA; the recorded voltage and current changes in the electrolytic cell are as follows: Figure 3 , Figure 4 As shown, and denoted as U respectively. dc,m I dc,m The sampling interval is 1ms.

[0079] Figure 3 , Figure 4 The disturbance is applied at a time of 2 seconds, and the value of U is taken from the time 1.999 seconds prior to the disturbance. dc,p I dc,p Value U dc,0 =0.9037, I dc,0 =0.9585. Take U dc,p I dc,p Data after 2 seconds are denoted as U. dc,f I dc,f Their values ​​are respectively related to U dc,0 I dc,0 The difference is calculated to form the disturbance change data ΔU dc ΔI dc .

[0080] With ΔU dc As the input to the second-order system, with ΔI dc As the output of a second-order system. In Matlab, lsqnonlin is used to identify the parameters K1, K2, T1, and T2 with minimum variance. The lsqnonlin function requires the error function and the initial values ​​of the parameters K1, T1, K2, and T2 (corresponding to Prms(1), Prms(2), Prms(3), and Prms(4) respectively). The initial values ​​of K1, K2, T1, and T2 are all set to 1. The error function can be written as:

[0081] function[Error]=calculate_error(Prms)

[0082] sys_1=tf([Prms(1)*Prms(4)+Prms(3)*Prms(2)

[0083] Prms(1)+Prms(3)],[Prms(2)*Prms(4)Prms(2)+Prms(4)1]);

[0084] out_y=lsim(sys_1,dUdc,t_in);

[0085] Error = out_y - dIdc;

[0086] end

[0087] In the `calculate_error` function, `dUdc` corresponds to `ΔU`. dc dIdc corresponds to ΔI dc .

[0088] Calculations show K1 = 0.364068, T1 = 0.237277, K2 = 1.653980, and T2 = 1.677734. Therefore, the per-unit values ​​of the electrolytic cell parameters are: R Al1 =2.746742, R Al2 =0.604602, L Al1 =0.651738, L Al2 =1.014362, E Al =0.428802. Converted to nominal values, they are: 7.125048Ω, 1.568338Ω, 1.690608H, 2.631254H, 556.155985V.

[0089] Using the aforementioned electrolytic aluminum parameters based on ΔU dc Calculated ΔI dc *Compared with measured ΔI dc For example Figure 5 As shown. From Figure 5 As can be seen from this, the method of this patent can accurately reflect the dynamic characteristics of the electrolytic cell.

[0090] It should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit it. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the spirit and scope of the technical solutions of the present invention, and all such modifications or substitutions should be covered within the scope of the claims of the present invention.

Claims

1. A method for determining simulation parameters of an aluminum electrolytic cell, characterized in that, include: The electrolytic current of the electrolytic cell is perturbed, the voltage and current data of the electrolytic cell are recorded, and then normalized. The electrolytic cell includes: Through the first resistor R AL1 Second resistor R AL2 respectively with the first inductor L Al1 Second inductor L Al2 The series branches are connected in parallel and then connected to the voltage source E. Al The electrolytic cell is simulated by connecting them in series; Define the voltage data during disturbance as follows The current data is ; Define the values ​​at the time step before the perturbation as follows: , ; A second-order system is established based on the dynamic process of the electrolyzer; The second-order system is represented as: in, , , , For system parameters; The per-unit values ​​of the parameters of the electrolytic cell are expressed as follows: By inputting voltage and current disturbance change data into the second-order system, the simulation parameters of the electrolytic cell are determined.

2. The method for determining simulation parameters of an electrolytic aluminum cell as described in claim 1, characterized in that: The data after standardization is represented as follows: in, , These are the rated operating voltage and rated operating current of the electrolytic cell, respectively.

3. The method for determining simulation parameters of an electrolytic aluminum cell as described in claim 2, characterized in that: Pick , The values ​​at the time step before the perturbation are denoted as follows: , ; Pick , The data after the disturbance time are respectively denoted as , .

4. The method for determining simulation parameters of an electrolytic aluminum cell as described in claim 3, characterized in that: The disturbance change data is represented as follows:

5. The method for determining simulation parameters of an electrolytic aluminum cell as described in claim 4, characterized in that: by As input to a second-order system ,by As the output of a second-order system Using nonlinear square functions to identify with minimum variance , , , The parameter is used to obtain its corresponding value.

6. The method for determining simulation parameters of an electrolytic aluminum cell as described in claim 5, characterized in that: Convert the per-unit values ​​of each parameter of the electrolytic cell to named values ​​to obtain , , , , ,in ; Based on the connection relationship of the electrolytic cell components, the nominal values ​​are imported into the simulation software to simulate the dynamic characteristics of the electrolytic cell.

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