Grading ring fitting parameter optimization method for extra-high voltage substation equipment

Abstract

The invention belongs to the technical field of high voltage and insulation, and provides a grading ring fitting parameter optimization method for extra-high voltage substation equipment, which comprises the steps of working condition determination, grading ring finite element model construction, optimization structure parameter initialization, optimization design model construction, structure optimization and parameter verification. According to the method, the genetic algorithm is introduced, so that the design efficiency is improved, the artificial experience error is reduced, and the design process is more scientific, accurate and efficient; by considering the electric field distribution, the impulse discharge characteristic and the corona onset voltage, the local electric field concentration is avoided, so that the grading ring fitting does not generate excessive discharge or breakdown under the high voltage impulse, and the risk of equipment failure is reduced.

Description

Technical Field

[0001] The present invention relates to the field of high voltage and insulation technology, and in particular to a method for optimizing parameters of a grading ring fitting for ultra-high voltage substation equipment. Background Art

[0002] The distance between the power energy center and the load center is mostly between 800 and 3000 km. UHV transmission technology has the advantages of large capacity, long distance, low energy consumption, small land area and good economy, and has been vigorously developed. However, with the increase of voltage level, lines and equipment are more prone to corona discharge. The energy loss, noise and electromagnetic interference caused by corona discharge will reach a considerable level in some cases. An important measure to prevent corona in power equipment is to set up a grading shielding ring. There are more than a thousand grading rings installed at the connection of the inlet and outlet lines of substation equipment. Therefore, reducing the maximum field strength on the surface of the grading ring is one of the effective measures to solve the corona of substations. With the development of the power system, especially the construction of ultra-high voltage and ultra-high voltage transmission lines, higher requirements are put forward for the structural optimization of the grading ring. In theory, the optimization of the grading ring can improve the electrical uniformity of the equipment, reduce the corona starting field strength of the equipment, reduce the discharge and contamination of the equipment, and extend the service life of the equipment. In practice, the optimization of the grading ring can save material costs, reduce equipment weight, reduce the space occupied by equipment, facilitate equipment installation and maintenance, and improve the reliability and safety of equipment operation. Therefore, how to scientifically determine the pipe diameter, ring diameter and number of layers of the equipment's grading ring has become an important research direction for improving the safety and economy of UHV substation equipment.

[0003] The traditional method is to design different parameters of the grading ring through simulation experiments, and then compare them to obtain the grading ring parameters when the electric field distribution is optimal. This method is not only time-consuming and labor-intensive, but also the electric field distribution when the simulated optimal grading ring parameters are obtained is very likely to be near the true optimal parameters, that is, the accuracy is insufficient. Summary of the invention

[0004] In order to overcome the deficiencies of the prior art, the purpose of the present invention is to provide a method for optimizing parameters of grading ring hardware for UHV substation equipment, so as to optimize the pipe diameter, ring diameter and number of layers of the grading ring of the equipment.

[0005] To achieve the above object, the present invention provides the following solutions:

[0006] A method for optimizing parameters of a grading ring fitting for ultra-high voltage substation equipment, comprising:

[0007] Determine the working conditions of the pressure equalizing ring to be optimized;

[0008] Construct a finite element model of the pressure equalizing ring in finite element simulation software;

[0009] Initializing the optimized structural parameters of the finite element model of the pressure equalizing ring according to the working conditions; the optimized structural parameters include: ring diameter, tube diameter and number of layers;

[0010] According to the electric field distribution, impulse discharge characteristics and corona inception voltage of the finite element model of the grading ring, an optimization design model is constructed based on a genetic algorithm;

[0011] Utilizing the optimization design model to perform structural optimization on the optimization structural parameters, and obtaining the optimal structural parameters of the pressure equalizing ring to be optimized;

[0012] The optimal structural parameters are verified using finite element simulation software to obtain a verification result. If the verification result is that the verification passes, the optimal structural parameters are output.

[0013] Preferably, the optimization design model is used to perform structural optimization on the optimization structural parameters to obtain the optimal structural parameters of the pressure equalizing ring to be optimized, including:

[0014] Determine the real number encoding form of the individual representation;

[0015] Randomly generate a group of initial individuals according to the real number coding form;

[0016] Using a preset objective function to evaluate the fitness of each of the initial individuals to obtain a fitness value;

[0017] Determine whether the fitness value meets a preset termination condition and obtain a determination result;

[0018] When the judgment result is that the termination condition is met, the initial individual meeting the termination condition is determined as the optimal structural parameter;

[0019] When the judgment result is that the termination condition is not met, the initial individual is updated by roulette selection according to the fitness value;

[0020] Perform crossover and mutation operations on the updated initial individuals, and return to the step of "using a preset objective function to evaluate the fitness of each initial individual to obtain a fitness value".

[0021] Preferably, determining the working conditions of the pressure equalizing ring to be optimized includes:

[0022] Determine the gap type; the gap type includes: phase-to-phase gap, phase-to-ground gap, gap between devices, and gap between devices and grounding body;

[0023] Determine the voltage level;

[0024] Select an equivalent model; the equivalent model includes: a rod-plate model, a ball-plate model, a ring-ring model and a line-surface model;

[0025] The parameters in the target UHV substation are calculated according to the gap type, the voltage level and the equivalent model to obtain the working conditions.

[0026] Preferably, a finite element model of the pressure equalizing ring is constructed in a finite element simulation software, including:

[0027] Selecting a pressure equalizing ring structure; the pressure equalizing ring structure includes: any one of a two-dimensional axisymmetric model and a three-dimensional model;

[0028] Constructing a pressure equalizing ring geometric model according to the pressure equalizing ring structure;

[0029] Determining the physical field, material properties and boundary conditions of the pressure equalizing ring geometric model;

[0030] The geometric model of the pressure equalizing ring is meshed to obtain a finite element model of the pressure equalizing ring.

[0031] Preferably, the calculation formula of the corona inception voltage is: V h =α·d; where V h is the corona onset voltage; α is the corona onset voltage coefficient in air; d is the gap distance.

[0032] Preferably, the real number encoding form is X=(D, d0, x); wherein X represents the initial individual; D is the ring diameter; d0 is the tube diameter; and x is the number of layers.

[0033] Preferably, the objective function is: F(y)=w1·f1(y)+w2·f2(y)+w3·f3(y); wherein, F(y) is the fitness value; w1, w2, w3 are the first weight coefficient, the second weight coefficient and the third weight coefficient respectively; f1(y) is the uniformity of the electric field distribution; f2(y) is the corona inception voltage; f3(x) is the impact discharge characteristic.

[0034] Preferably, the expression selected by the roulette wheel is: Among them, P i represents the probability that the i-th initial individual is inherited to the next generation population; F i is the fitness value of the i-th initial individual; N represents the total number of the initial individuals.

[0035] The present invention discloses the following technical effects:

[0036] The present invention provides a method for optimizing parameters of grading ring fittings for UHV substation equipment. By introducing a genetic algorithm, the problem of manual experience error is solved, and the design efficiency is improved. By considering the electric field distribution, impulse discharge characteristics and corona inception voltage, the problem of excessive discharge or breakdown of the grading ring fittings under high voltage impulse caused by local electric field concentration is solved, and the optimization of the pipe diameter, ring diameter and number of layers of the grading ring fittings is achieved. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative labor.

[0038] Figure 1 A schematic diagram of a parameter optimization process of a grading ring fitting for UHV substation equipment provided by an embodiment of the present invention;

[0039] Figure 2 A schematic diagram of the optimal structural parameter acquisition process provided by an embodiment of the present invention. DETAILED DESCRIPTION

[0040] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0041] The purpose of the present invention is to provide a method for optimizing parameters of grading ring hardware for ultra-high voltage substation equipment, so as to optimize the pipe diameter, ring diameter and number of layers of the grading ring of the equipment.

[0042] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, the present invention is further described in detail below with reference to the accompanying drawings and specific embodiments.

[0043] Figure 1 A schematic diagram of a parameter optimization process of a grading ring fitting for a UHV substation device provided by an embodiment of the present invention is shown in FIG. Figure 1 As shown, the present invention provides a method for optimizing parameters of a grading ring fitting for UHV substation equipment, comprising:

[0044] Step 100: Determine the working conditions of the pressure equalizing ring to be optimized;

[0045] Step 200: constructing a finite element model of the pressure equalizing ring in finite element simulation software;

[0046] Step 300: Initializing the optimized structural parameters of the finite element model of the pressure equalizing ring according to the working conditions; the optimized structural parameters include: ring diameter, tube diameter and number of layers;

[0047] Step 400: constructing an optimization design model based on a genetic algorithm according to the electric field distribution, impulse discharge characteristics and corona inception voltage of the finite element model of the grading ring;

[0048] Step 500: Optimizing the optimized structural parameters using the optimized design model to obtain the optimal structural parameters of the pressure equalizing ring to be optimized;

[0049] Step 600: Utilize finite element simulation software to verify the optimal structural parameters and obtain verification results. If the verification result is that the verification is passed, the optimal structural parameters are output.

[0050] refer to Figure 2 , using the optimization design model to perform structural optimization on the optimization structural parameters to obtain the optimal structural parameters of the pressure equalizing ring to be optimized, including:

[0051] Determine the real number encoding form of the individual representation;

[0052] Randomly generate a group of initial individuals according to the real number coding form;

[0053] Using a preset objective function to evaluate the fitness of each of the initial individuals to obtain a fitness value;

[0054] Determine whether the fitness value meets a preset termination condition and obtain a determination result;

[0055] When the judgment result is that the termination condition is met, the initial individual meeting the termination condition is determined as the optimal structural parameter;

[0056] When the judgment result is that the termination condition is not met, the initial individual is updated by roulette selection according to the fitness value;

[0057] Perform crossover and mutation operations on the updated initial individuals, and return to the step of "using a preset objective function to evaluate the fitness of each initial individual to obtain a fitness value".

[0058] Preferably, determining the working conditions of the pressure equalizing ring to be optimized includes:

[0059] Determine the gap type; the gap type includes: phase-to-phase gap, phase-to-ground gap, gap between devices, and gap between devices and grounding body;

[0060] Determine the voltage level;

[0061] Select an equivalent model; the equivalent model includes: a rod-plate model, a ball-plate model, a ring-ring model and a line-surface model;

[0062] The parameters in the target UHV substation are calculated according to the gap type, the voltage level and the equivalent model to obtain the working conditions.

[0063] Specifically, a finite element model of the pressure equalizing ring is constructed in the finite element simulation software, including:

[0064] Selecting a pressure equalizing ring structure; the pressure equalizing ring structure includes: any one of a two-dimensional axisymmetric model and a three-dimensional model;

[0065] Constructing a pressure equalizing ring geometric model according to the pressure equalizing ring structure;

[0066] Determining the physical field, material properties and boundary conditions of the pressure equalizing ring geometric model;

[0067] The geometric model of the pressure equalizing ring is meshed to obtain a finite element model of the pressure equalizing ring.

[0068] Furthermore, the calculation formula of the corona inception voltage is: V h =α·d; where V h is the corona onset voltage; α is the corona onset voltage coefficient in air; d is the gap distance.

[0069] Specifically, the real number encoding form is X=(D, d0, x); wherein X represents the initial individual; D is the ring diameter; d0 is the tube diameter; and x is the number of layers.

[0070] Furthermore, the objective function is: F(y)=w1·f1(y)+w2·f2(y)+w3·f3(y); wherein, F(y) is the fitness value; w1, w2, w3 are the first weight coefficient, the second weight coefficient and the third weight coefficient respectively; f1(y) is the uniformity of the electric field distribution; f2(y) is the corona inception voltage; f3(x) is the impact discharge characteristic.

[0071] Specifically, the expression selected by the roulette wheel is: Among them, P i represents the probability that the i-th initial individual is inherited to the next generation population; F i is the fitness value of the i-th initial individual; N represents the total number of the initial individuals.

[0072] Furthermore, common gap types include: phase-to-phase gap (i.e., the safe distance between different phases in the same system), phase-to-ground gap (i.e., the gap between the equipment and the ground), equipment-to-equipment gap (the gap between different electrical equipment), and equipment-to-ground gap (the distance between electrical equipment and the grounding system).

[0073] Specifically, voltage level is a key parameter in clearance design. As voltage increases, the safety clearance between devices and between devices and the ground also needs to increase.

[0074] Preferably, when calculating the gap, some equivalent models are usually used to simplify the electric field calculation: rod-plate model, sphere-plate model, ring-ring model, line-surface model.

[0075] Furthermore, based on the above conditions, the design values ​​of various key gaps in the UHV substation are finally determined through calculation.

[0076] Preferably, electric field distribution modeling: based on the predicted basic parameters of the grading ring, a finite element model of the grading ring is established in the finite element simulation software, and the electric field distribution of the grading ring and the uneven intensity of the electric field are calculated, as follows: first, a two-dimensional axisymmetric model or a three-dimensional model is established according to the structure of the grading ring, and a geometric model of the grading ring is established. Appropriate physical fields and material properties are selected, boundary conditions are set, and meshing is performed. Smaller mesh units are used for the main parts of the grading ring. For areas where the electric field does not change much, larger mesh units can be used. Now, the electric field distribution of the grading ring and the uneven intensity of the electric field are calculated.

[0077] Furthermore, as an important analysis result, electric field distribution usually has two forms of expression: graphical diagram and discrete data. Electric field inhomogeneity is an important parameter to measure the degree of variation of electric field strength in space. It can characterize whether the electric field distribution is smooth and whether there is a concentrated or strong electric field area. To calculate the inhomogeneous strength of the electric field, first select the area you need to analyze in the simulation area, then export the discrete data of the electric field strength from the simulation software, calculate the electric field strength of each node in the area, and finally calculate the inhomogeneity of the electric field strength according to the calculation formula.

[0078] Furthermore, the impulse discharge characteristics and the calculation of the corona inception voltage are: the transient simulation analysis method is used to simulate the impulse voltage that may occur in the UHV substation, and the electric field response of the grading ring under the impulse voltage is analyzed. The output data of the electric field response is usually presented in the form of time-varying data, including the change of the electric field intensity over time and the instantaneous electric field distribution. At the same time, the corona inception voltage on the surface of the grading ring fitting is calculated to ensure that the designed grading ring fitting does not cause corona discharge under the working voltage. The corona inception voltage can be calculated by the following formula:

[0079] V h =α·d

[0080] Preferably, as a global optimization method, genetic algorithm can effectively search the solution space and find the global optimal solution. The specific steps are as follows:

[0081] 1) Construction of optimization design model: According to the electric field distribution, impulse discharge characteristics, and corona inception voltage, a target optimization design model is established. The design goal is: the maximum electric field strength on the surface of the grading ring is less than the initial corona field strength of the grading ring. The input layer is the structural parameters of the grading ring, including the ring diameter, tube diameter, and number of layers of the grading ring. The output layer is the maximum electric field strength on the surface of the grading ring. The mapping relationship is: (E1) = F(D, d0, x), where E1 is the maximum electric field strength on the surface of the grading ring. The basic idea is to obtain a set of structural parameters D, d0, and x so that the maximum electric field strength on the surface of the grading ring is less than the initial corona field strength of the grading ring.

[0082] 2) Individual representation and encoding: In the genetic algorithm, an individual is represented as a solution, that is, a combination of design parameters of the pressure equalizing ring. The design parameters include: the ring diameter of the pressure equalizing ring, the pipe diameter of the pressure equalizing ring, and the number of layers of the pressure equalizing ring. These design parameters can be represented by real number encoding, and each individual is a vector containing D, d0, and x. For example, the individual encoding form can be: X = (D, d0, x).

[0083] 3) Initialize the population: Randomly generate a group of initial individuals, each of which represents a possible design solution. Assume that the size of the initial population is N, that is, N different design solutions are generated. The initial individuals can meet some basic constraints of the design, such as the reasonable range of the pipe diameter and the ring diameter.

[0084] 4) Fitness evaluation: The fitness of each individual is evaluated through the objective function F(y). The fitness value reflects the pros and cons of the design scheme. The higher the fitness of the individual, the closer its design parameters are to the optimal solution. In order to perform fitness evaluation, it is first necessary to define an objective function F(y), which can comprehensively reflect multiple performance indicators of the pressure equalizing ring design. The objective function usually consists of multiple sub-objectives, as follows:

[0085] F(y)=w1·f1(y)+w2·f2(y)+w3·f3(y)

[0086] 5) Selection operation: select the next generation of individuals according to their fitness. Individuals with higher fitness are more likely to be selected. Roulette selection: select individuals according to the proportion of their fitness. Suppose the population size is N, and the fitness of individual i is F i , then the probability of individual i being selected and inherited to the next generation is:

[0087] 6) Crossover operation: Generate new individuals by exchanging part of the genetic information of two individuals, so as to explore a wider design space. In the design of the equalizing ring, the crossover operation crosses between the tube diameter, ring diameter and number of layers. Common methods of crossover operation include: single-point crossover (randomly select the crossover point, exchange the genetic information of the two parent individuals, and generate two child individuals); multi-point crossover (select multiple crossover points and exchange genetic information at multiple positions).

[0088] 7) Mutation operation: Randomly change certain genes of individuals to enhance the diversity of the population. Mutation operation helps the genetic algorithm to jump out of the local optimal solution and evolve to the global optimal solution. In the design of the equalizing ring, small random changes can be made to the pipe diameter, ring diameter, number of layers, etc. Commonly used methods include: small mutation (making small adjustments to a certain design parameter (such as pipe diameter or ring diameter)); random reset mutation (randomly select a design parameter and assign a new random value).

[0089] 8) Calculate the fitness of each individual in the population again to check whether the one with the highest fitness meets the termination condition (the maximum field strength on the surface of the equalizing ring is less than the initial corona field strength of the equalizing ring). If so, output the optimal solution. If not, return to step 5) to start a new round of optimization for the new population.

[0090] 9) Optimal solution extraction: After several generations of optimization, the genetic algorithm will eventually converge to an optimal solution, that is, the best design parameter combination of the pressure equalizing ring.

[0091] Furthermore, simulation verification: Finite element simulation software is used to verify the optimization results to ensure their feasibility in practical applications.

[0092] The beneficial effects of the present invention are as follows:

[0093] (1) The present invention significantly improves design efficiency and reduces manual experience errors through the introduction of genetic algorithms, making the design process more scientific, accurate and efficient.

[0094] (2) The present invention ensures the uniformity of the electric field by accurately simulating the electric field distribution of the voltage-equalizing ring hardware in the device. The optimized design avoids local electric field concentration, thereby preventing the corona discharge phenomenon.

[0095] (3) The present invention improves the ability of the grading ring to withstand transient impulse voltages, and the design optimization can prevent the grading ring hardware from excessive discharge or breakdown under high voltage impact, thereby significantly reducing the risk of equipment failure.

[0096] (4) The present invention determines the appropriate distance between the pressure equalizing ring and other equipment components to ensure safe operation of the equipment.

[0097] (5) The present invention reduces the use of materials through accurate calculations while meeting the design requirements. After the design parameters of the equalizing ring hardware, such as the pipe diameter, ring diameter and number of layers, are optimized, unnecessary material waste can be reduced, thereby reducing production costs.

[0098] The various embodiments in this specification are described in a progressive manner, and each embodiment focuses on the differences from other embodiments. The same or similar parts between the various embodiments can be referenced to each other.

[0099] The principles and implementation methods of the present invention are described in this article using specific examples. The description of the above embodiments is only used to help understand the method and core idea of ​​the present invention. At the same time, for those skilled in the art, according to the idea of ​​the present invention, there will be changes in the specific implementation methods and application scope. In summary, the content of this specification should not be understood as limiting the present invention.

Claims

1. A method for optimizing parameters of grading ring fittings for ultra-high voltage substation equipment, characterized in that: include: Determine the working conditions of the pressure equalizing ring to be optimized; Construct a finite element model of the pressure equalizing ring in finite element simulation software; Initializing the optimized structural parameters of the finite element model of the pressure equalizing ring according to the working conditions; The optimized structural parameters include: ring diameter, tube diameter and number of layers; According to the electric field distribution, impulse discharge characteristics and corona inception voltage of the finite element model of the grading ring, an optimization design model is constructed based on a genetic algorithm; Utilizing the optimization design model to perform structural optimization on the optimization structural parameters, and obtaining the optimal structural parameters of the pressure equalizing ring to be optimized; The optimal structural parameters are verified using finite element simulation software to obtain a verification result. If the verification result is that the verification passes, the optimal structural parameters are output.

2. A method for optimizing parameters of grading ring fittings for UHV substation equipment according to claim 1, characterized in that: The optimization design model is used to perform structural optimization on the optimization structural parameters to obtain the optimal structural parameters of the pressure equalizing ring to be optimized, including: Determine the real number encoding form of the individual representation; Randomly generate a group of initial individuals according to the real number coding form; Using a preset objective function to evaluate the fitness of each of the initial individuals to obtain a fitness value; Determine whether the fitness value meets a preset termination condition and obtain a determination result; When the judgment result is that the termination condition is met, the initial individual meeting the termination condition is determined as the optimal structural parameter; When the judgment result is that the termination condition is not met, the initial individual is updated by roulette selection according to the fitness value; Perform crossover and mutation operations on the updated initial individuals, and return to the step of "using a preset objective function to evaluate the fitness of each of the initial individuals to obtain a fitness value".

3. The method for optimizing parameters of grading ring fittings for UHV substation equipment according to claim 1, characterized in that: Determine the working conditions of the pressure equalizing ring to be optimized, including: Determine the gap type; the gap type includes: phase-to-phase gap, phase-to-ground gap, gap between devices, and gap between devices and grounding body; Determine the voltage level; Select an equivalent model; the equivalent model includes: a rod-plate model, a ball-plate model, a ring-ring model and a line-surface model; The parameters in the target UHV substation are calculated according to the gap type, the voltage level and the equivalent model to obtain the working conditions.

4. The method for optimizing parameters of grading ring fittings for UHV substation equipment according to claim 1, characterized in that: Construct a finite element model of the pressure equalizing ring in the finite element simulation software, including: Selecting a pressure equalizing ring structure; the pressure equalizing ring structure includes: any one of a two-dimensional axisymmetric model and a three-dimensional model; Constructing a pressure equalizing ring geometric model according to the pressure equalizing ring structure; Determining the physical field, material properties and boundary conditions of the pressure equalizing ring geometric model; The geometric model of the pressure equalizing ring is meshed to obtain a finite element model of the pressure equalizing ring.

5. The method for optimizing parameters of grading ring fittings for UHV substation equipment according to claim 1, characterized in that: The calculation formula of the corona inception voltage is: V h =α·d; Among them, V h is the corona onset voltage; α is the corona onset voltage coefficient in air; d is the gap distance.

6. A method for optimizing parameters of grading ring fittings for UHV substation equipment according to claim 2, characterized in that: The real number encoding form is X=(D, d0, x); wherein X represents the initial individual; D is the ring diameter; d0 is the tube diameter; and x is the number of layers.

7. The method for optimizing parameters of grading ring fittings for UHV substation equipment according to claim 2, characterized in that: The objective function is: F(y)=w1·f1(y)+w2·f2(y)+w3·f3(y); wherein, F(y) is the fitness value; w1, w2, w3 are the first weight coefficient, the second weight coefficient and the third weight coefficient respectively; f1(y) is the uniformity of the electric field distribution; f2(y) is the corona inception voltage; f3(x) is the impact discharge characteristic.

8. The method for optimizing parameters of grading ring fittings for UHV substation equipment according to claim 2, characterized in that: The expression for the roulette wheel selection is: Among them, P i represents the probability that the i-th initial individual is inherited to the next generation population; F i is the fitness value of the i-th initial individual; N represents the total number of the initial individuals.

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