# Power flow calculation method of uncertain power system

## A power system and power flow calculation technology, which is applied to AC networks of the same frequency with different sources, etc., can solve problems such as affecting convergence, probability error, affecting the accuracy of calculation results, etc., to improve accuracy and improve convergence. Effect

Active Publication Date: 2019-11-29

CHINA AGRI UNIV +1

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## AI-Extracted Technical Summary

### Problems solved by technology

[0004] However, the calculation methods of the above categories (1) and (2) will always introduce a certain amount of probability error, which will affect the accuracy of the calculation results. The method of category (3) can solve the above problems to a certain extent, but its reactive power output It is controlled by the upper limit and the lower limit. When the reactiv...

### Method used

Compared with prior art, the embodiment of the present invention utilizes the method for interval analysis, has dealt with reactive power exceeding limit problem by complementary constraint, and by introducing nonlinear function (Fischer-Burmesiter function, be called for short FB function), inequality The constraints are converted into equality constraints, and the Krawczyk-Moore interval iterative algorithm is used to solve the power flow constraint equations, so that the calculation results have higher accuracy and better convergence.

The power flow calculation device of the uncertain power system provided by the embodiment of the present invention, by setting the corresponding execution module, adopts the method of interval analysis, handles reactive power exceeding the limit through complementary constraints, and introduces a nonlinear function, and the inequality constraint Converting to equality constraints can effectively improve the accuracy of power flow calculation in uncertain power systems, and effectively improve the convergence.

The power flow calculation method of the uncertain power system provided by the embodiment of the present invention is a more adaptable power flow calculation method based on interval analysis, by adopting the interval analysis method, utilizing complementary constraints to process reactive power exceeding the limit, And introducing a nonlinear function to convert inequality constraints into equality constraints can effectively improve the accuracy of power flow calculations in uncertain power systems, and effectively improve the convergence.

Wherein optional, in actual problem calculation, according to the information of the power flow calculation of determining load, the range of each variable is narrowed down to the vicinity interval of determining the power flow solution, which can reduce the number of iterations and speed up the calculation efficiency. However, if the interval is too large or small, it is difficult to obtain a true interval range solution.

[0023] T...

## Abstract

The embodiment of the invention provides a power flow calculation method of an uncertain power system. The method comprises the steps of introducing reactive power constraints to a PV node and a balance node of the uncertain power system, and constructing a reactive out-of-limit hybrid power flow complementation constraint equation set of the uncertain power system by introducing a given nonlinearfunction based on the reactive power constraints; defining the active power, the node voltage and the uncertain network parameters of the uncertain power system as interval variables, and respectively representing the interval variables with bounded closed intervals; and solving the hybrid power flow complementation constraint equation set by adopting a given iterative algorithm based on the bounded closed intervals to obtain a voltage change interval of power flow calculation of the uncertain power system. According to the embodiment of the invention, the power flow calculation accuracy of the uncertain power system can be effectively improved, and the convergence is effectively improved.

Application Domain

Ac networks with different sources same frequency

Technology Topic

Non linear functionsTidal current +6

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## Examples

- Experimental program(1)

### Example Embodiment

[0022] In order to make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be described clearly and completely in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments It is a part of the embodiments of the present invention, but not all the embodiments. Based on the embodiments in the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative work shall fall within the protection scope of the embodiments of the present invention.

[0023] Aiming at the problem of poor accuracy and convergence in the prior art when performing power flow calculations for uncertain power systems, the embodiments of the present invention adopt an interval analysis method to deal with reactive power violations through complementary constraints, and introduce nonlinear functions, Converting inequality constraints to equality constraints can effectively improve the accuracy of power flow calculations for uncertain power systems and effectively improve convergence. Hereinafter, the embodiments of the present invention will be explained and introduced in detail through a plurality of embodiments.

[0024] figure 1 It is a schematic flow chart of a method for power flow calculation of an uncertain power system provided by an embodiment of the present invention, such as figure 1 As shown, the method includes:

[0025] S101, introduce reactive power constraints to the PV nodes and balance nodes of the uncertain power system, and construct the uncertain power system reactive power based on the reactive power constraints and the power flow constraint equation of the uncertain power system by introducing a given nonlinear function Complementary constraint equations for over-limit mixed power flow.

[0026] It can be understood that the embodiment of the present invention firstly introduces the reactive power constraints of the PV node and the balance node to realize the reactive power compensation of the uncertain power system for the problem of reactive power overrun of the uncertain power system. After that, a non-linear function is introduced and applied to the reactive power constraint. On this basis, combined with the basic power flow constraint equation of the uncertain power system, the complementary constraint equation set of the uncertain power system is reconstructed, that is, the hybrid power flow complementary constraint equation set for the reactive power overrun.

[0027] S102: Define the active power of the uncertain power system, the node voltage, and the uncertain network parameters of the hybrid power flow complementary constraint equation set as interval variables, and respectively express them in bounded closed intervals.

[0028] It can be understood that, taking into account the uncertainty of the data in the uncertain power system, the embodiment of the present invention transforms the uncertain power flow problem into a nonlinear interval problem, and the uncertain power system's active power, node voltage, and mixed The uncertain network parameters of the power flow complementary constraint equations are set in intervals, and combined with the selection theory of interval extremes, the nonlinear programming problem is decomposed and solved, and the upper and lower bounds of the real and imaginary parts of the node voltage in the power flow solution are obtained. , Thus giving the operating range of the system.

[0029] S103: Based on the bounded closed interval, a given iterative algorithm is used to solve the hybrid power flow complementary constraint equation set to obtain the voltage change interval for the power flow calculation of the uncertain power system.

[0030] It can be understood that solving the uncertain power flow equation is to express the variable factors in the uncertain model in the form of intervals, and set the state variables (such as load voltage, phase angle, generator output) as intervals, and seek to meet the constraints. Control variables (eg reactive power compensation, generator terminal voltage). Specifically, on the basis of the above interval setting, the embodiment of the present invention adopts an interval analysis method to iteratively solve the hybrid power flow complementary constraint equations obtained above to obtain an interval of uncertain data, such as a voltage change interval.

[0031] The power flow calculation method for uncertain power systems provided by the embodiments of the present invention is a more adaptable power flow calculation method based on interval analysis. The interval analysis method is used to deal with reactive power overruns by using complementary constraints and the introduction of non- The linear function transforms the inequality constraint into the equality constraint, which can effectively improve the accuracy of the power flow calculation of the uncertain power system and effectively improve the convergence.

[0032] Among them, optional according to the foregoing embodiments, the power flow constraint equation of the uncertain power system is as follows:

[0033]

[0034]

[0035] For the PV node, the node voltage equation is:

[0036]

[0037] In the formula, n represents the number of nodes, e i , F i Represents the real and imaginary parts of the voltage at node i, G ij , B ij Represents the (i,j)th component of the nodal admittance matrix, P i set , Q i set Represents the constant active power and reactive power of node i, U i set Indicates the voltage control target.

[0038] Based on this, the steps to introduce reactive power constraints to the PV nodes and balance nodes of the uncertain power system include:

[0039] Reactive power constraints are introduced to PV nodes and balance nodes as follows:

[0040]

[0041] Where Q i max And Q i min Respectively represent the maximum and minimum reactive power at node i, Q i Represents the actual reactive power at node i.

[0042] It can be understood that for power systems with uncertain targets, the power flow constraint equations in Cartesian coordinates can be constructed. The basic power flow constraint equation can be expressed in the form of power mismatch, that is, the form of the power flow constraint equation of the above-mentioned uncertain power system. For the PV node, the second formula in the above power flow constraint equation can be replaced by the node voltage equation, namely:

[0043]

[0044] Therefore, for PV nodes and balance nodes, the introduction of reactive power constraints can be written as the mathematical expression of the above reactive power constraints.

[0045] It is understandable that the division of PV nodes, PQ nodes and balance nodes in the uncertain power system is not absolutely constant. The main reason why PV node can control its node voltage to a certain set value is that it has adjustable reactive power output, but its reactive power output is controlled by upper and lower limits, namely

[0046] If the reactive power output exceeds the limit, that is or At this time, the reactive power can only be maintained at its upper limit or lower limit, and the node voltage can no longer be maintained at the set value. At this time, the PV node is transformed into a PQ node, and the balance node is transformed into a Qθ node. Iterative calculations until there is no violation of restrictions. That is, for PV nodes and balance nodes, the power out-of-bounds situation needs to be considered. When the reactive power exceeds the limit value, Q takes the maximum or minimum value. At this time, the PV node is transformed into a PQ node and iterative calculation needs to be performed again.

[0047] In view of this, the embodiment of the present invention optimizes the original reactive power complementary constraints. That is, after the step of introducing reactive power constraints to the PV nodes and balance nodes of the uncertain power system, the method of the embodiment of the present invention may further include: optimizing the reactive power constraints as follows:

[0048]

[0049] Where Is the introduced relaxation factor, and

[0050] Correspondingly, based on the power flow constraint equation and the optimized reactive power constraint, a hybrid power flow complementary constraint equation set is constructed.

[0051] Among them, according to the above embodiments, the steps of constructing a hybrid power flow complementary constraint equation set of uncertain power system reactive power exceeding limit by introducing a given nonlinear function are optional, including:

[0052] First, introduce the given nonlinear function as follows:

[0053]

[0054] In the formula, μ is the relaxation factor.

[0055] Second, apply the given nonlinear function to the reactive power constraint, and obtain the nonlinear equation of the reactive power constraint as follows:

[0056]

[0057] Third, based on the power flow constraint equation and the reactive power constraint nonlinear equation, the hybrid power flow complementary constraint equation set is obtained as follows:

[0058]

[0059] It can be understood that, in order to solve the problem of complementary constraints, the Fischer-Burmesiter (FB) function is introduced here, and the Fischer-Burmesiter (FB) function can be used to reconstruct the hybrid complementary constraints. The expression is shown above. This function is semi-smooth, can be solved effectively by the NR method, and can smoothly change the search direction at the sharp corners of the constraint exchange, so it is more reliable.

[0060] It is understandable that in order to avoid the problem that the FB function φ(μ,ν) is not differentiable at (0,0), a small relaxation factor μ=10 is introduced -10.

[0061] After that, by applying the function φ(μ,v) to the complementary constraints in the power flow calculation, a new equation description can be obtained, that is, the reactive power constraint nonlinear equation is as above.

[0062] Finally, the use of the power flow constraint equation and the reactive power constraint nonlinear equation together form the hybrid power flow complementary constraint equation set shown above.

[0063] In the embodiment of the present invention, by introducing the FB function, the inequality constraint is converted into the equality constraint condition, which can solve the accuracy problem more effectively.

[0064] Among them, according to the above embodiments, the step of defining the active power of the uncertain power system, the node voltage, and the uncertain network parameters of the hybrid power flow complementary constraint equation set as interval variables, specifically includes: taking the active power as the first Interval variables, and define the fluctuation range of the first interval variables as the first bounded closed interval; define the generator node voltages and uncertain network parameters in the uncertain power system as the second interval variables, and unify the second interval variables Expressed by the second bounded closed interval.

[0065] Specifically, in an uncertain system, the active power P is regarded as a variable in a certain interval, and its possible fluctuation range is defined as a bounded closed interval Referred to as Where P i with They are the upper and lower bounds of active power. The generator node voltage and uncertain network parameters are also defined as interval variables, which are uniformly represented by a bounded closed interval x, x and Respectively its lower bound and upper bound.

[0066] Optionally, in the actual problem calculation, according to the load flow calculation information, narrow the range of each variable to the vicinity of the determined power flow solution, which can reduce the number of iterations and speed up the calculation efficiency. However, if the interval is too large or small, it is difficult to obtain a true interval range solution.

[0067] Wherein, optional according to the foregoing embodiments, the step of solving the hybrid power flow complementary constraint equation set specifically includes: using Gauss-Seidel iterative algorithm or Krawczyk iterative algorithm to solve the hybrid power flow complementary constraint equation set. Among them, if the Krawczyk iterative algorithm is used to solve the mixed power flow complementary constraint equations, the iterative formula defining the iterative algorithm is as follows:

[0068]

[0069] Where iterative operator Expressed as:

[0070]

[0071] In the formula, J(x) represents the Jacobian matrix, Represents the preprocessing matrix, C represents the J(x) inverse matrix where x takes the center of the interval, I represents the identity matrix, Represents the rounding of x, and x represents the generator node voltage and the defined interval of uncertain network parameters.

[0072] Specifically, suppose the nonlinear equation system is:

[0073]

[0074] Introduction mapping Then 2N equations can be obtained from the above-mentioned mixed power flow complementary constraint equations. For the convenience of expression, the power flow calculation constraint equations can be expressed as:

[0075]

[0076] The solution of interval nonlinear equations requires the iterative method. At present, the main iterative methods for solving are Newton iterative method and Krawczyk iterative method. The principle is to take the intersection of the interval of the previous iteration with the iterative operator when the step length is corrected to obtain a new interval vector.

[0077] The iterative formula of the iterative method is:

[0078]

[0079] For operator H, you can choose the interval Newton operator:

[0080]

[0081] In the formula, J(x) is the Jacobian matrix, Represents the outward rounding of x.

[0082] In each step of the above iterative algorithm calculation, the inverse matrix of J(x) must be found. However, in the case of multiple variables, the Jacobian matrix is an interval matrix and cannot be directly inverted, so it is not a practical method.

[0083] In view of this, the embodiment of the present invention adopts the Gauss-Seidel iterative algorithm or the Krawczyk iterative algorithm to solve the interval equation. The embodiment of the present invention adopts an improved Krawczyk operator for the selection of the operator H. This method is a new iterative form improved on the basis of the Newton operator, and there is no need to solve the interval nonlinear equation system in the iterative process. Therefore, the matrix inversion operation is avoided, but a reasonable initial iteration interval needs to be selected when using it.

[0084] For the Krawczyk iterative algorithm, the above iterative formula can be modified as:

[0085]

[0086] Thus, the iterative operator It can be expressed as:

[0087]

[0088] The criterion for stopping iteration of Krawczyk algorithm can be set as:

[0089]

[0090] among them ε It is a preset value and a very small positive number.

[0091] In order to further illustrate the technical solutions of the embodiments of the present invention, the embodiments of the present invention provide the following specific processing procedures based on the foregoing embodiments, but do not limit the protection scope of the embodiments of the present invention.

[0092] Such as figure 2 Shown is a schematic flow chart of a method for calculating power flow of an uncertain power system according to another embodiment of the present invention, including the following steps:

[0093] First, according to the equipment operating state of the target uncertain power system, the basic power flow constraint equation of the target uncertain power system is established, and the complementary constraints of the reactive power exceeding the limit are carried out.

[0094] Secondly, in order to solve the inequality problem caused by the complementary constraints, nonlinear (Fischer-Burmesiter, FB) functions are introduced to obtain the hybrid power flow complementary constraint equations.

[0095] Thirdly, the interval analysis method is used to set the interval setting for the active power and node voltage of the power system with uncertain target, and the uncertain network parameters of the hybrid power flow complementary constraint equations.

[0096] Finally, on the basis of the above interval setting, the Krawczyk-Moore interval iterative algorithm is used to calculate the uncertain interval power flow for the above-mentioned mixed power flow complementary constraint equations to obtain the power flow calculation results.

[0097] Compared with the prior art, the embodiment of the present invention uses the method of interval analysis to deal with the problem of reactive power over-limit through complementary constraints, and by introducing a nonlinear function (Fischer-Burmesiter function, FB function for short), the inequality constraint is converted into Equality constraints, and the Krawczyk-Moore interval iteration algorithm is used to solve the power flow constraint equations, so that the calculation results have higher accuracy and better convergence.

[0098] Based on the same concept, the embodiments of the present invention provide a power flow calculation device of an uncertain power system according to the foregoing embodiments, and the device is used to implement the power flow calculation of the uncertain power system in the foregoing embodiments. Therefore, the descriptions and definitions in the power flow calculation methods for uncertain power systems in the foregoing embodiments can be used to understand the execution modules in the embodiments of the present invention. For details, please refer to the foregoing embodiments and will not be repeated here.

[0099] According to an embodiment of the present invention, the structure of the power flow calculation device of the uncertain power system is as image 3 Shown is a schematic structural diagram of a power flow calculation device for an uncertain power system provided by an embodiment of the present invention. The device can be used to implement the power flow calculation of the uncertain power system in the foregoing method embodiments. The device includes: a complementary constraint module 301 , Section setting module 302 and calculation module 303. among them:

[0100] The complementary constraint module 301 is used to introduce reactive power constraints to the PV nodes and balance nodes of the uncertain power system. Based on the reactive power constraints and the power flow constraint equations of the uncertain power system, the uncertainty is constructed by introducing a given nonlinear function The hybrid power flow complementary constraint equation set of power system reactive power exceeds the limit; the interval setting module 302 is used to define the uncertain power system active power, node voltage and the uncertain network parameters of the hybrid power flow complementary constraint equation set as interval variables, and They are represented by bounded closed intervals respectively; the calculation module 303 is used to solve the hybrid power flow complementary constraint equations based on the bounded closed interval and using a given iterative algorithm to obtain the voltage variation interval of the uncertain power system power flow calculation.

[0101] Specifically, in response to the problem of reactive power over-limit of the uncertain power system, the complementary constraint module 301 introduces the reactive power constraints of the PV node and the balance node to realize the reactive power compensation of the uncertain power system. Afterwards, the complementary constraint module 301 introduces a nonlinear function and applies the nonlinear function to the reactive power constraint. On this basis, the complementary constraint module 301 combines the basic power flow constraint equations of the uncertain power system to reconstruct the complementary constraint equation set of the uncertain power system, that is, the hybrid power flow complementary constraint equation set for reactive power overruns.

[0102] Then, taking into account the uncertainty of the data in the uncertain power system, the interval setting module 302 converts the uncertainty power flow problem into a nonlinear interval problem, which is suitable for the active power, node voltage, and mixed power flow of the uncertain power system. The uncertain network parameters of the complementary constraint equations are set in intervals, and combined with the selection theory of interval extremes, the nonlinear programming problem is decomposed and solved, and the upper and lower bounds of the real and imaginary parts of the node voltage in the power flow solution are obtained. This gives the operating range of the system.

[0103] Finally, on the basis of the above interval setting, the calculation module 303 adopts an interval analysis method to iteratively solve the hybrid power flow complementary constraint equations obtained above to obtain an interval of uncertain data, such as a voltage change interval.

[0104] The power flow calculation device of the uncertain power system provided by the embodiment of the present invention adopts the method of interval analysis by setting the corresponding execution module, and uses the complementary constraint to deal with the reactive power exceeding limit, and introduces the nonlinear function to convert the inequality constraint into the equivalent The formula constraint can effectively improve the accuracy of the power flow calculation of the uncertain power system and effectively improve the convergence.

[0105] It can be understood that, in the embodiments of the present invention, a hardware processor may be used to implement various related program modules in the devices of the foregoing embodiments. In addition, the power flow calculation device of the uncertain power system in the embodiment of the present invention uses the above program modules to realize the power flow calculation process of the uncertain power system in the above method embodiments. In the power flow calculation of the power system, the beneficial effects produced by the device of the embodiment of the present invention are the same as the corresponding method embodiments described above, and reference may be made to the above method embodiments, which will not be repeated here.

[0106] As yet another aspect of the embodiments of the present invention, this embodiment provides an electronic device based on the foregoing embodiments. The electronic device includes a memory, a processor, and a computer program stored in the memory and running on the processor, When the processor executes the computer program, it realizes the steps of the method for calculating the power flow of the uncertain power system as described in the foregoing embodiments.

[0107] Further, the electronic device of the embodiment of the present invention may also include a communication interface and a bus. reference Figure 4 , Is a schematic diagram of the physical structure of an electronic device provided by an embodiment of the present invention, and includes: at least one memory 401, at least one processor 402, a communication interface 403, and a bus 404.

[0108] Among them, the memory 401, the processor 402, and the communication interface 403 communicate with each other through the bus 404. The communication interface 403 is used for information transmission between the electronic device and the target uncertain power system data device; the memory 401 stores The computer program running on the processor 402, when the processor 402 executes the computer program, implements the steps of the method for calculating the power flow of the uncertain power system as described in the foregoing embodiments.

[0109] It can be understood that the electronic device includes at least a memory 401, a processor 402, a communication interface 403, and a bus 404, and the memory 401, the processor 402, and the communication interface 403 form a mutual communication connection through the bus 404, and can complete mutual communication. For example, the processor 402 reads the program instructions of the power flow calculation method of the uncertain power system from the memory 401. In addition, the communication interface 403 can also realize the communication connection between the electronic device and the target uncertain power system data device, and can complete mutual information transmission, such as reading the power system data through the communication interface 403.

[0110] When the electronic device is running, the processor 402 calls the program instructions in the memory 401 to execute the methods provided in the foregoing method embodiments, for example, including: introducing reactive power constraints on the PV nodes and balance nodes of the uncertain power system, and based on Reactive power constraints and the power flow constraint equations of uncertain power systems, by introducing a given nonlinear function, construct a hybrid power flow complementary constraint equation set of uncertain power system reactive power exceeding limits; the active power and node voltage of the power system will be uncertain And the uncertain network parameters of the complementary constraint equations of the mixed power flow are defined as interval variables and expressed in bounded closed intervals; based on the bounded closed interval, the given iterative algorithm is used to solve the complementary constraint equations of the mixed power flow, and the Determine the voltage change interval of the power flow calculation of the power system.

[0111] The above-mentioned program instructions in the memory 401 may be implemented in the form of a software functional unit and when sold or used as an independent product, they may be stored in a computer readable storage medium. Alternatively, all or part of the steps in the above-mentioned method embodiments may be implemented by a program instructing relevant hardware. The foregoing program may be stored in a computer readable storage medium. When the program is executed, the execution includes the above-mentioned method implementation. Example steps; and the aforementioned storage medium includes: U disk, mobile hard disk, read-only memory (Read-Only Memory, ROM), random access memory (Random Access Memory, RAM), magnetic disks or optical disks and other various programs that can store programs The medium of the code.

[0112] The embodiments of the present invention also provide a non-transitory computer-readable storage medium according to the foregoing embodiments, on which computer instructions are stored. When the computer instructions are executed by a computer, the uncertain power system as described in the foregoing embodiments is implemented. The steps of the power flow calculation method include, for example, introducing reactive power constraints to the PV nodes and balance nodes of the uncertain power system, and based on the reactive power constraints and the power flow constraint equations of the uncertain power system, by introducing a given nonlinear function , Construct a hybrid power flow complementary constraint equation set of uncertain power system reactive power overruns; define the active power, node voltage of the uncertain power system and the uncertain network parameters of the hybrid power flow complementary constraint equation set as interval variables, and use Bounded closed interval representation; based on the bounded closed interval, the given iterative algorithm is used to solve the hybrid power flow complementary constraint equation set, and obtain the voltage change interval of the uncertain power system power flow calculation.

[0113] The electronic equipment and the non-transitory computer-readable storage medium provided by the embodiments of the present invention execute the steps of the method for calculating the power flow of the uncertain power system described in the above embodiments, adopt the method of interval analysis, and deal with non-transitory constraints through complementary constraints. The work limit is exceeded, and nonlinear functions are introduced to convert inequality constraints into equality constraints, which can effectively improve the accuracy of power flow calculations for uncertain power systems and effectively improve convergence.

[0114] It can be understood that the embodiments of the apparatus, electronic equipment, and storage medium described above are merely illustrative, and the units described as separate components may or may not be physically separated, and may be located in one place, or It can also be distributed to different network units. Some or all of the modules can be selected according to actual needs to achieve the objectives of the solutions of the embodiments. Those of ordinary skill in the art can understand and implement without creative work.

[0115] Through the description of the above implementation manners, those skilled in the art can clearly understand that each implementation manner can be implemented by software plus a necessary general hardware platform, and of course, it can also be implemented by hardware. Based on this understanding, the above technical solution essentially or the part that contributes to the existing technology can be embodied in the form of a software product, and the computer software product can be stored in a computer-readable storage medium, such as a U disk or a mobile hard disk. , ROM, RAM, magnetic disk or optical disk, etc., including several instructions to make a computer device (such as a personal computer, server, or network device, etc.) execute the foregoing method embodiments or some parts of the method embodiments Methods.

[0116] In addition, those skilled in the art should understand that in the application documents of the embodiments of the present invention, the terms "including", "including" or any other variations thereof are intended to cover non-exclusive inclusions, so as to include a series of The process, method, article, or equipment of the element includes not only those elements, but also other elements that are not explicitly listed, or also include elements inherent to the process, method, article, or equipment. If there are no more restrictions, the element defined by the sentence "including a..." does not exclude the existence of other same elements in the process, method, article, or equipment including the element.

[0117] In the description of the embodiments of the present invention, a large number of specific details are described. However, it should be understood that the embodiments of the embodiments of the present invention can be practiced without these specific details. In some instances, well-known methods, structures and technologies are not shown in detail, so as not to obscure the understanding of this specification. Similarly, it should be understood that in order to simplify the disclosure of the embodiments of the present invention and help understand one or more of the various aspects of the invention, in the above description of the exemplary embodiments of the embodiments of the present invention, various features of the embodiments of the present invention are sometimes referred to as Grouped together into a single embodiment, figure, or description thereof.

[0118] However, the disclosed method should not be interpreted as reflecting the intention that the claimed embodiment of the invention requires more features than those explicitly stated in each claim. More precisely, as reflected in the claims, the inventive aspect lies in less than all the features of a single embodiment disclosed previously. Therefore, the claims following the specific embodiment are thus explicitly incorporated into the specific embodiment, wherein each claim itself serves as a separate embodiment of the embodiment of the present invention.

[0119] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the embodiments of the present invention, but not to limit them; although the embodiments of the present invention are described in detail with reference to the foregoing embodiments, those skilled in the art should understand: It is still possible to modify the technical solutions recorded in the foregoing embodiments, or equivalently replace some of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the technical solutions of the embodiments of the present invention. Spirit and scope.

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