A method for radially identifying the temperature rise rate of conductors inside GIS based on temperature gradient

Abstract

This invention discloses a method for radially identifying the temperature rise rate of conductors inside a GIS based on a temperature gradient, comprising the following steps: S1, establishing a transient temperature rise equilibrium mathematical model for the GIS shell; S2, establishing a transient temperature rise mathematical model for the GIS; S3, defining an equilibrium coefficient and determining its value based on GIS structural parameters, material properties, and fluid parameters; S4, determining the interval division of the conductor temperature rise rate based on the relationship between the temperature rise rate of the conductor and the environment and the equilibrium coefficient; S5, based on monitoring data from outside the GIS; S6, deriving the relationship between the environmental temperature rise rate, the shell temperature rise rate, and the conductor temperature rise rate; S7, deriving the conductor temperature rise rate interval based on the shell transient temperature rise equilibrium mathematical model. This invention employs the above-mentioned method for radially identifying the temperature rise rate of conductors inside a GIS based on a temperature gradient, eliminating the need to implant sensors inside the equipment. This detection method is safe, low-cost, and highly efficient.

Description

Technical Field

[0001] This invention relates to the field of online monitoring and intelligent condition diagnosis technology for high-voltage power equipment, and in particular to a method for radially identifying the temperature rise rate of internal conductors of GIS based on temperature gradient. Background Technology

[0002] Gas-insulated switchgear (GIS) is a critical piece of equipment in substations, bearing the heavy responsibility of load control and safe operation of the power system; therefore, its operational reliability is paramount. Consequently, GIS undergoes extremely stringent requirements in its design, manufacturing, and installation. However, in actual operation, numerous GIS overheating and flashover accidents have occurred due to poor contact, causing severe equipment damage and even power outages resulting in significant economic losses. The airtightness of GIS is both a guarantee of its safety and stability and a major reason why its internal temperature distribution is difficult to monitor.

[0003] Methods for detecting charged temperatures mainly include infrared detection technology, fiber Bragg grating method, and surface acoustic wave (SAW) sensing method. Infrared technology's main advantage is indirect temperature measurement, avoiding electromagnetic interference and high-voltage isolation issues, and its simplicity and ease of use; however, its accuracy is not high, and it is susceptible to external environmental factors in practical applications. The fiber Bragg grating method offers advantages such as a wide temperature measurement range, small size, resistance to electromagnetic interference, and good insulation. However, its disadvantages include susceptibility to external environmental interference, and the introduction of fiber Bragg gratings into the equipment can lead to insulation and sealing issues. SAW sensing method's advantage is the direct monitoring of internal temperature, making it less susceptible to external environmental factors; however, the sensor's placement within the GIS cavity raises concerns about internal insulation strength. Summary of the Invention

[0004] The purpose of this invention is to provide a method for radially identifying the temperature rise rate of conductors inside a GIS based on a temperature gradient. This method monitors and acquires external data of the GIS equipment, the transient changes in the casing temperature and ambient temperature, without the need to implant sensors inside the equipment. This detection method is safe, low-cost, and highly efficient.

[0005] This invention provides a method for radially identifying the temperature rise rate of conductors inside a GIS based on a temperature gradient, comprising the following steps:

[0006] S1. Establish a mathematical model for the transient temperature rise equilibrium of the GIS shell;

[0007] S2. Establish a mathematical model for transient temperature rise in GIS;

[0008] S3. Define the equilibrium coefficient and determine its value based on the GIS structural parameters, material properties, and fluid parameters.

[0009] S4. Divide the conductor temperature rise rate into intervals, and determine the interval division of the conductor temperature rise rate based on the relationship between the temperature rise rate of the conductor and the environment and the equilibrium coefficient.

[0010] S5. Based on the monitoring data outside the GIS, obtain the shell temperature rise rate and the ambient temperature rise rate;

[0011] S6. Based on the GIS transient temperature rise mathematical model, the relationship between the ambient temperature rise rate, the shell temperature rise rate, and the conductor temperature rise rate is derived.

[0012] S7. Based on the mathematical model of transient temperature rise equilibrium of the shell, the temperature rise rate range of the conductor is obtained. The equilibrium coefficient corresponding to the specific interval divided according to the temperature rise rate of the conductor is substituted into the corresponding equilibrium coefficient relationship. The one that satisfies the condition is the final temperature rise rate of the conductor.

[0013] Preferably, in S1, the mathematical model for the transient temperature rise equilibrium of the GIS shell, without considering radiation, has the following expression:

[0014]

[0015] When considering radiation, the mathematical model for the transient temperature rise equilibrium of the GIS casing is expressed as follows:

[0016]

[0017] In the formula, T e T is the temperature of the outer wall surface of the casing. c T is the temperature of the outer wall surface of the conductor. ∞ The ambient temperature is given; g is the acceleration due to gravity; α is the coefficient of volume expansion of the fluid; ν is the kinematic viscosity of the fluid; c p η is the specific heat capacity at constant pressure; η is the fluid dynamic viscosity; constants C1, C2 and coefficients n1, n2 are determined experimentally; λ is the thermal conductivity; l1, l2 are characteristic lengths; the unit area of ​​the conductor and the shell is represented by A1 and A2, respectively; ε e ε c σ represents the emissivity of the outer surface of the shell and the conductor, respectively; σ is the Stefan-Boltzmann constant.

[0018] Preferably, in S2, the mathematical model for transient temperature rise in GIS is:

[0019]

[0020] In the formula, T ∞ The ambient temperature; T e T represents the casing temperature. c The conductor temperature.

[0021] Preferably, in S3, the balance coefficient is defined as follows:

[0022] B = -f(T) c ,T e ,T ∞ );

[0023] Ignoring radiation:

[0024] f(T c ,T e ,T ∞ )=f1(T c ,T e ,T ∞ );

[0025] Considering radiation:

[0026] f(T c ,T e ,T ∞ )=f2(T c ,T e ,T ∞ ).

[0027] Preferably, in S4, the division interval of the conductor temperature rise rate is determined according to the temperature rise rate law of the conductor.

[0028] Preferably, the GIS equipment uses a 72.5kV GIS busbar.

[0029] Therefore, the present invention adopts the above-mentioned method for radial identification of the temperature rise rate of the internal conductor of GIS based on temperature gradient. By monitoring and acquiring the transient change process of external data of GIS equipment, shell temperature and ambient temperature, there is no need to implant sensors inside the equipment. This detection method has no safety hazards, is low in cost and highly efficient.

[0030] The technical solution of the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. Attached Figure Description

[0031] Figure 1 This is a schematic diagram illustrating the relationship between the temperature rise rate of the conductor and the environment and the equilibrium coefficient in a method for radially identifying the temperature rise rate of an internal conductor of a GIS based on a temperature gradient, according to the present invention.

[0032] Figure 2 This is a flowchart of a method for radially identifying the temperature rise rate of internal conductors in GIS based on a temperature gradient, according to the present invention. Detailed Implementation

[0033] The technical solution of the present invention will be further described below with reference to the accompanying drawings and embodiments.

[0034] Unless otherwise defined, the technical or scientific terms used in this invention shall have the ordinary meaning as understood by one of ordinary skill in the art to which this invention pertains.

[0035] The terms "first," "second," and similar words used in this invention do not indicate any order, quantity, or importance, but are merely used to distinguish different components. Terms such as "comprising" or "including" mean that the element or object preceding the word encompasses the elements or objects listed after the word and their equivalents, without excluding other elements or objects. Terms such as "connected" or "linked" are not limited to physical or mechanical connections, but can include electrical connections, whether direct or indirect. Terms such as "upper," "lower," "left," and "right" are used only to indicate relative positional relationships; when the absolute position of the described object changes, the relative positional relationship may also change accordingly.

[0036] Example 1

[0037] like Figures 1-2 As shown, the present invention provides a method for radially identifying the temperature rise rate of conductors inside a GIS based on a temperature gradient, comprising the following steps:

[0038] S1. Establish a mathematical model for the transient temperature rise equilibrium of the GIS shell;

[0039] In S1, the mathematical model for the transient temperature rise equilibrium of the GIS shell, without considering radiation, has the following expression:

[0040]

[0041] When considering radiation, the mathematical model for the transient temperature rise equilibrium of the GIS casing is expressed as follows:

[0042]

[0043] In the formula, T e T is the temperature of the outer wall surface of the casing. c T is the temperature of the outer wall surface of the conductor. ∞ ν is the ambient temperature (fluid temperature unaffected by the shell temperature); g is the acceleration due to gravity; α is the fluid's volumetric expansion coefficient; ν is the fluid's kinematic viscosity; c p η is the specific heat capacity at constant pressure; η is the fluid dynamic viscosity; constants C1, C2 and coefficients n1, n2 are determined experimentally; λ is the thermal conductivity; l1, l2 are characteristic lengths; the unit area of ​​the conductor and the shell is represented by A1 and A2, respectively; ε e ε c σ represents the emissivity of the outer surfaces of the shell and conductor, respectively; σ is the Stefan-Boltzmann constant, with a value of 5.67 × 10⁻⁶. -8 W / (m 2 ·K4 ).

[0044] function f2(T) c ,T e ,T ∞ Similarly, it is composed of T c ,T e ,T ∞ The nonlinear equation controlled by three unknowns, compared to the function f1(T) c ,T e ,T ∞ The addition of radiation-related polynomials makes the process more complex and nonlinear. Therefore, the weight of the influence of the conductor's and the external environment's temperature rise rate on the shell's temperature rise rate is directly affected by T. c ,T e ,T ∞ The influence is indirectly affected by the material properties and fluid parameters in a and b.

[0045] S2. Establish a mathematical model for transient temperature rise in GIS;

[0046] In S2, the mathematical model for transient temperature rise in GIS is:

[0047]

[0048] In the formula, T ∞ The ambient temperature; T e T represents the casing temperature. c The conductor temperature.

[0049] S3. Define the equilibrium coefficient and determine its value based on the GIS structural parameters, material properties, and fluid parameters.

[0050] In S3, the balance coefficient is defined as:

[0051] B = -f(T) c ,T e ,T ∞ );

[0052] Ignoring radiation:

[0053] f(T c ,T e ,T ∞ )=f1(T c ,T e ,T ∞ );

[0054] Considering radiation:

[0055] f(T c ,T e ,T ∞ )=f2(Tc ,T e ,T ∞ ).

[0056] When the GIS structure parameters remain unchanged, when T c ,T e ,T ∞ Once determined, the remaining material properties and fluid parameters are also determined, and therefore the value of B is also determined. The value of B varies under different conditions, but it is approximately equal within a certain range. Therefore, this range can be divided based on the external environment or the temperature rise rate of the conductor.

[0057] S4. Divide the conductor temperature rise rate into intervals, and determine the interval division of the conductor temperature rise rate based on the relationship between the temperature rise rate of the conductor and the environment and the equilibrium coefficient.

[0058] In S4, the intervals for the conductor's temperature rise rate are determined based on the conductor's temperature rise rate law, and the conductor's temperature rise rate gradually decreases during the temperature increase process.

[0059] S5. Based on external monitoring data from the GIS, the temperature rise rate of the outer casing and the ambient temperature rise rate are obtained. The temperature rise rate of the conductor is relatively regular, gradually decreasing as the temperature increases. However, the temperature rise rate of the external environment is random, depending on the current weather conditions. Therefore, intervals are divided based on the temperature rise rate of the conductor. When T... c ,T e ,T ∞ When the value is determined, the balance coefficient B = -f(T) c ,T e ,T ∞ )and and The relationship between them is as follows Figure 1 As shown.

[0060] S6. Based on the GIS transient temperature rise mathematical model, the relationship between the ambient temperature rise rate, the shell temperature rise rate, and the conductor temperature rise rate is derived. Based on the above theory, a method for identifying the internal conductor temperature rise rate based on monitoring data of the shell and ambient temperatures is obtained. First, the shell temperature rise rate is obtained based on monitoring data from outside the GIS. With the rate of ambient temperature rise Then determine Whether it is true or not, continue to make a judgment. Therefore, based on the mathematical model of transient temperature rise in GIS, the following conclusions are drawn. and The relationship between the three;

[0061] S7. Based on the mathematical model of transient temperature rise equilibrium of the shell, the temperature rise rate range of the conductor is obtained. The equilibrium coefficient corresponding to the specific interval divided according to the temperature rise rate of the conductor is substituted into the corresponding equilibrium coefficient relationship. The one that satisfies the condition is the final temperature rise rate of the conductor.

[0062] The conclusion is The possible range, and substitute the equilibrium coefficient corresponding to the specific range divided by the conductor's temperature rise rate into it. The corresponding equilibrium coefficient relationship, whichever satisfies the conditions, is the correct solution. The process for identifying the temperature rise rate of internal conductors in GIS is as follows: Figure 2 As shown.

[0063] To verify the effectiveness of the proposed method, a temperature rise test was conducted on a 72.5kV GIS busbar. The temperature of the conductor inside the GIS busbar, as well as the corresponding outer shell and ambient temperature, were monitored and collected by thermocouples during the temperature rise test. The data processing and analysis are shown in Table 1.

[0064] Table 1

[0065]

[0066] The identification method is verified using two time periods (258-270 min and 300-307 min) within interval 2 of Table 1 as examples. Within the 300-307 min time period... The balance coefficient is taken as B = -0.5, therefore we can obtain Within the time period of 258-270 minutes The balance coefficient is taken as B = -0.156, therefore we can obtain At this point, the invention fully meets the above-mentioned requirements.

[0067] Therefore, the present invention adopts the above-mentioned method for radial identification of the temperature rise rate of the internal conductor of GIS based on temperature gradient. By monitoring and acquiring the transient change process of external data of GIS equipment, shell temperature and ambient temperature, there is no need to implant sensors inside the equipment. This detection method has no safety hazards, is low in cost and highly efficient.

[0068] The above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit them. 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 still be made to the technical solutions of the present invention, and these modifications or equivalent substitutions cannot cause the modified technical solutions to deviate from the spirit and scope of the technical solutions of the present invention.

Claims

1. A method for radially identifying the temperature rise rate of conductors inside a GIS based on a temperature gradient, characterized in that, Includes the following steps: S1. Establish a mathematical model for the transient temperature rise equilibrium of the GIS shell; without considering radiation, the mathematical model expression for the transient temperature rise equilibrium of the GIS shell is: ； When considering radiation, the mathematical model for the transient temperature rise equilibrium of the GIS casing is expressed as follows: ； In the formula, This refers to the temperature of the outer wall surface of the casing. Temperature of the outer wall surface of the conductor; Ambient temperature; It is the heat capacity at constant pressure; For fluid dynamic viscosity; constant , With coefficient , Determined experimentally; the unit area of ​​the conductor and the shell are expressed as... and ; , These are the emissivity of the outer surfaces of the shell and the conductor, respectively. This is the Stefan-Boltzmann constant, with a value of ; S2. Establish a mathematical model for transient temperature rise in GIS; the mathematical model for transient temperature rise in GIS is as follows: ； In the formula, Ambient temperature; This refers to the casing temperature; For conductor temperature; S3. Define the equilibrium coefficient and determine its value based on the GIS structural parameters, material properties, and fluid parameters; the equilibrium coefficient is defined as follows: ； Ignoring radiation: ； Considering radiation: ； S4. Divide the conductor temperature rise rate into intervals, and determine the interval division of the conductor temperature rise rate based on the relationship between the temperature rise rate of the conductor and the environment and the equilibrium coefficient; the interval division of the conductor temperature rise rate is determined according to the temperature rise rate law of the conductor, and the conductor temperature rise rate gradually decreases during the temperature increase process. S5. Based on the monitoring data outside the GIS, obtain the shell temperature rise rate and the ambient temperature rise rate; S6. Based on the GIS transient temperature rise mathematical model, the relationship between the ambient temperature rise rate, the shell temperature rise rate, and the conductor temperature rise rate is derived. S7. Based on the mathematical model of transient temperature rise equilibrium of the shell, the temperature rise rate range of the conductor is obtained. The equilibrium coefficient corresponding to the specific interval divided according to the temperature rise rate of the conductor is substituted into the corresponding equilibrium coefficient relationship. The one that satisfies the condition is the final temperature rise rate of the conductor.

2. The method for radially identifying the temperature rise rate of conductors inside GIS based on a temperature gradient according to claim 1, characterized in that, In step S1, the formulas for calculating parameters a and b are as follows: ； ； in, It is the acceleration due to gravity; is the coefficient of volumetric expansion of the fluid; The fluid's kinematic viscosity; Thermal conductivity; , The characteristic length is denoted as .

3. The method for radially identifying the temperature rise rate of internal conductors of GIS based on a temperature gradient according to claim 1, characterized in that, The GIS equipment uses a 72.5kV GIS busbar.

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