Power system flexibility evaluation method and device considering new energy permeability

Abstract

The invention relates to a power system flexibility evaluation method and device considering new energy permeability. According to the method, a key link limiting the flexibility of a power system is selected, and a power system automatic generation control (AGC) nonlinear model considering the new energy permeability is established; introducing a concept of an attraction domain and an estimation method thereof, and calculating attraction domain estimation values of the AGC of the power system under different new energy permeability conditions; based on the relationship between the attraction domain estimation value of the AGC state variable of the power system and the flexible supply capability of the system, the flexible supply capability of the power system under different new energy permeability conditions is evaluated. According to the method, the flexible supply capability of the power system can be visually evaluated under different new energy permeability conditions, AGC stable operation of the power system can be realized, and support is provided for flexible planning and operation of the power system.

Description

Technical Field

[0001] The present invention belongs to the field of power systems and new energy, and specifically relates to a method and device for evaluating the flexibility of a power system taking new energy penetration into consideration. Background Art

[0002] As the proportion of new energy sources gradually increases, the uncertainty and volatility of the power system have significantly increased, and the difficulty of real-time power balance has gradually increased. In order to ensure the balance of supply and demand during operation, the power system must have sufficient response capabilities, and flexibility has become one of the key characteristics to ensure the stable operation of the power system. Therefore, in order to improve the overall flexibility level of the power system, it is necessary to quantitatively evaluate the flexibility of the system at different time scales.

[0003] The existing power system flexibility assessment is mainly carried out from three aspects: system flexibility supply capacity, demand and margin. Commonly used flexibility assessment methods mainly include the following two categories:

[0004] 1. Evaluation method based on inherent properties of the system: Comprehensively consider the inherent properties of the units such as system capacity, minimum output level, operating range, and climbing ability, and evaluate the system flexibility supply capacity in an equivalent and aggregated manner. This type of method is easy to calculate and can reflect the flexibility characteristics of the system, but it does not consider the impact of new energy penetration and cannot intuitively feedback the system flexibility acceptance level.

[0005] 2. Evaluation method based on timing simulation: Through simulations at different time scales, considering probabilistic indicators such as the expected insufficient ramping resource index (IRRE) and the flexibility defect period index (PFD), the system flexibility is evaluated to see whether it is sufficient. This method requires a large number of simulation calculations and is suitable for system flexibility evaluation at long time scales such as planning. Summary of the invention

[0006] The present invention proposes a method and device for evaluating the flexibility of an electric power system taking into account the penetration rate of renewable energy, so as to evaluate the stability domain and flexibility supply capacity of electric power systems with different penetration rates of renewable energy.

[0007] First, a method for evaluating the flexibility of power systems considering the penetration rate of renewable energy is proposed, including:

[0008] Given the renewable energy penetration rate, the AGC nonlinear model of the power system with flexibility constraints is updated;

[0009] Based on the updated AGC nonlinear model, the attraction domain estimation method is used to calculate the AGC attraction domain estimation ellipsoid Ω(P1), that is, the stable domain;

[0010] Based on the updated AGC nonlinear model, calculate the maximum anti-interference capability α2 of the AGC;

[0011] The flexibility supply capacity of AGC is calculated by the maximum anti-interference capacity α2. The flexibility supply capacity of AGC includes the maximum net load fluctuation value allowed to be connected to AGC |ΔP L |, where

[0012] The estimated ellipsoid of the AGC attraction domain is the stable domain. The new energy penetration rate is updated, and the stable domain of the power system AGC considering the power supply flexibility constraint under different new energy penetration rates and the absolute value of the maximum net load fluctuation allowed to be connected |ΔP are calculated. L |.

[0013] Secondly, a power system flexibility assessment device considering the penetration rate of new energy is proposed, including:

[0014] The AGC nonlinear model with flexibility constraints is updated according to the given new energy penetration rate:

[0015] A stable domain calculation module is configured to: calculate the AGC attraction domain estimation ellipsoid Ω(P1), i.e., the stable domain, based on the updated AGC nonlinear model using an attraction domain estimation method;

[0016] The flexibility supply capacity calculation module is configured to: calculate the maximum anti-interference capacity α2 of the AGC based on the updated AGC nonlinear model, and calculate the flexibility supply capacity of the AGC through the maximum anti-interference capacity α2, that is, the maximum net load fluctuation value allowed to be connected to the AGC |ΔP L |, where

[0017] In the first and second aspects above, the renewable energy penetration rate is updated, and the stability domain of the power system AGC considering the power supply flexibility constraint and the absolute value of the maximum net load fluctuation allowed to be connected |ΔP are calculated under different renewable energy penetration rates. L |.

[0018] In a third aspect, a computer is provided, comprising: a processor; a memory, comprising one or more computer program modules; wherein the one or more computer program modules are stored in the memory and configured to be executed by the processor, and the one or more computer program modules include instructions for implementing the method for evaluating the flexibility of the power system considering the penetration rate of new energy.

[0019] In a fourth aspect, a computer-readable storage medium is provided for storing non-temporary computer-readable instructions, which, when executed by a computer, can implement the method for evaluating the flexibility of the power system taking into account the penetration rate of new energy.

[0020] The innovation of the present invention lies in that, on the basis of considering different renewable energy penetration rates, a power system flexibility evaluation method suitable for the AGC time scale is proposed, which intuitively reflects the flexibility supply capacity of the power system during the AGC process. On the basis of considering the impact of different renewable energy penetration rates on the power system AGC parameters, for the power system AGC nonlinear model containing flexibility links, an attraction domain estimation method is introduced to solve the stability domain of the nonlinear control system, and calculate the power system AGC flexibility supply capacity, that is, the maximum net load value that the power system can accept. The present invention directly solves the flexibility supply capacity of the system AGC under different renewable energy penetration rates, provides theoretical support for the access of renewable energy, and provides guarantee for the safe and stable operation of the power grid. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 It is a block diagram of a method for evaluating the flexibility of a power system taking into account the penetration rate of new energy sources provided by an embodiment of the present invention.

[0022] Figure 2 It is a flow chart of a method for evaluating the flexibility of a power system taking into account the penetration rate of new energy sources provided by one embodiment of the present invention.

[0023] Figure 3 It is an ellipsoid for estimating the attraction domain of the AGC nonlinear model of the power system under different new energy penetration rates provided by an embodiment of the present invention. DETAILED DESCRIPTION

[0024] This invention mainly uses the attraction domain estimation method to calculate the stability domain of the AGC nonlinear model of the power system containing flexibility links under different new energy penetration rates, and calculates the maximum net load value that the system AGC maximum generator set can accept. Figure 1 , Figure 2 The following is a block diagram and flow chart of the power system flexibility assessment method considering the penetration rate of renewable energy. The following first introduces the method in detail.

[0025] 1. Considering the impact of different new energy penetration rates, a nonlinear AGC model of the power system with power supply flexibility is established. Formula (1) is the mathematical formula of the model:

[0026] Where x∈R n , u∈R m , w∈R l are state variables, control variables and disturbance variables respectively; represents the derivative of x; A, B, E are the state matrix, control matrix and disturbance matrix respectively; F is the linear feedback matrix; σ(·) is the saturation function.

[0027] 2. Based on the model parameters of the speed regulator and prime mover of each generator in the power system, calculate the model parameters of the equivalent generator of the power system; based on the model parameters of the equivalent generator and the given new energy penetration rate K, that is, the proportion of different online synchronous generator sets K r =1-K, update and calculate the power system AGC control parameters (parameters in A, B, and F), including the equivalent inertia constant H, the equivalent unit droop coefficient R, and the equivalent power supply flexibility parameter P max , R rate .

[0028] The AGC nonlinear model is common knowledge for those skilled in the art. The matrix A, B, and F contain the new energy penetration rate K. The present invention will not introduce the mathematical formulas of the matrix A, B, E, and F. A large number of literature materials have relevant introductions. The new energy penetration rate K is updated, which means the AGC nonlinear model is updated. Specifically, the effective inertia constant H, the equivalent unit droop coefficient R, and the equivalent power flexibility parameter P are updated. max , R rat And other parameters.

[0029] 3. Given the new energy penetration rate, the attraction domain estimation method is used to calculate the attraction domain estimation ellipsoid Ω(P1) = {x0∈R n :x T P1x≤1}.

[0030] x0 is the initial state. Constraint (a) introduces the shape reference set X R , X R For a specified bounded convex set, the maximum attraction domain estimate is obtained by optimizing the parameter α1. When α1 is larger, the attraction domain estimate ellipsoid Ω(P1) is larger; constraints (b) and (c) are sufficient conditions for the attraction domain estimate ellipsoid Ω(P1) to satisfy the shrinkage invariance. P1 is a positive definite matrix; H is an auxiliary matrix; I m is the identity matrix of order m; D i is a diagonal matrix with diagonal elements of 0 or 1, D i - =I m -D i ; For a square matrix S, He(S)=S+S T ; α1 is a positive real number and satisfies α1X R ={α1x:x∈X R}; function L(H) = {x∈R n :||H x || ∞ ≤1} means H x Unsaturated areas.

[0031] 4. Assume that there exists a positive real number α2 such that the nonlinear system perturbation w satisfies w T w≤α2, α2 represents the maximum anti-disturbance capability of the nonlinear system. The maximum anti-disturbance capability α2 and the attraction domain ellipsoid Ω(P2) considering the system disturbance w can be obtained by formula (3).

[0032] Where η is a given positive real number, which can be obtained by scanning from (0,∞) to obtain the global maximum value of α2; Ω(P2) is the attraction domain ellipsoid considering the system perturbation w, w T w≤α2, P2 is a positive definite matrix, H is an auxiliary matrix, D i is a diagonal matrix with diagonal elements of 0 or 1, D i - =I m -D i , I m is the unit matrix of order m. For a square matrix S, He(S) = S + S T , function L(H)={x∈R n :||H x || ∞ ≤1} means H x Unsaturated areas.

[0033] 5. According to the maximum anti-disturbance capability α2 of the nonlinear system, the present invention can calculate the flexibility supply capability of the system AGC considering the power supply flexibility constraint under different new energy penetration rates, that is, the absolute value of the maximum net load fluctuation allowed to be connected by the nonlinear system |ΔP L |.

[0034] The present invention also proposes an embodiment of a power system flexibility assessment device taking into account the penetration rate of new energy. The device includes: an AGC nonlinear model with flexibility constraints, a stable domain calculation module and a flexible supply capacity calculation module. The AGC nonlinear model has been introduced above. The stable domain calculation module is configured to calculate the AGC attraction domain estimation ellipsoid Ω(P1), i.e., the stable domain, based on the updated AGC nonlinear model and using the attraction domain estimation method according to formula (2).

[0035] The flexibility supply capacity calculation module is configured as follows: Based on the updated AGC nonlinear model, the maximum anti-interference capacity α2 of the AGC is calculated according to formula (3), and the flexibility supply capacity of the AGC is calculated through the maximum anti-interference capacity α2, that is, the maximum net load fluctuation value allowed to be connected to the AGC |ΔP L |, where

[0036] Update the renewable energy penetration rate, and calculate the stability domain of the power system AGC considering the power supply flexibility constraint under different renewable energy penetration rates and the absolute value of the maximum net load fluctuation allowed to be connected |ΔP L |.

[0037] The present invention also provides an embodiment of a computer. The computer includes a processor and a memory. The memory is used to store non-temporary computer-readable instructions (e.g., one or more computer program modules). The processor is used to run non-temporary computer-readable instructions, and when the non-temporary computer-readable instructions are run by the processor, one or more steps in the power system flexibility assessment method considering the penetration rate of new energy sources described above can be executed. The memory and the processor can be interconnected through a bus system and / or other forms of connection mechanisms.

[0038] For example, the processor may be a central processing unit (CPU), a graphics processing unit (GPU), or other forms of processing units with data processing capabilities and / or program execution capabilities. For example, the central processing unit (CPU) may be an X86 or ARM architecture, etc. The processor may be a general-purpose processor or a special-purpose processor, and may control other components in the computer to perform desired functions.

[0039] For example, the memory may include any combination of one or more computer program products, and the computer program product may include various forms of computer-readable storage media, such as volatile memory and / or non-volatile memory. Volatile memory may include, for example, random access memory (RAM) and / or cache memory (cache), etc. Non-volatile memory may include, for example, read-only memory (ROM), hard disk, erasable programmable read-only memory (EPROM), compact disc read-only memory (CD-ROM), USB memory, flash memory, etc. One or more computer program modules may be stored on the computer-readable storage medium, and the processor may run one or more computer program modules to implement various functions of the computer.

[0040] The present invention also provides an embodiment of a computer-readable storage medium, which is used to store non-transitory computer-readable instructions. When the non-transitory computer-readable instructions are executed by a computer, one or more steps in the above-mentioned method for evaluating the flexibility of an electric power system considering the penetration rate of new energy can be implemented. When the method and device for evaluating the flexibility of an electric power system considering the penetration rate of new energy provided in the embodiment of the present application are sold or used as independent products, they can be stored in a computer-readable storage medium. For relevant instructions on the storage medium, please refer to the corresponding description of the memory in the computer above, which will not be repeated here.

[0041] Figure 3It is the estimated ellipsoid of the attraction domain of the AGC nonlinear model of the power system under different new energy penetration rates. From the results, it can be seen that when the new energy penetration rate K changes from 0% to 20%, 40%, and 60%, the proportions of different online synchronous generators Kr are 1, 0.8, 0.6, and 0.4, respectively, and the estimated ellipsoid of the attraction domain of the AGC nonlinear model of the power system becomes smaller. Therefore, it can be seen that when the new energy penetration rate increases, the stability domain of the AGC of the power system becomes smaller. In the actual calculation, x in formula (1) is a 4*1 variable, and the state variable x=[ΔP c ,ΔY,ΔP m ,Δf]. The estimated ellipsoid is the estimated region where each state variable is stable, so it is also 4-dimensional. (a), (b), (c), and (d) are the projections of the 4-dimensional ellipsoid on the 3-dimensional and 2-dimensional planes respectively.

Claims

1. A method for evaluating the flexibility of a power system considering the penetration rate of renewable energy, characterized in that: include: According to the given renewable energy penetration rate, the AGC nonlinear model of the power system with flexibility constraints is updated; Based on the updated AGC nonlinear model, the attraction domain estimation method is used to calculate the AGC attraction domain estimation ellipsoid Ω(P1); Based on the updated AGC nonlinear model, calculate the maximum anti-interference capability α2 of the AGC; The flexibility supply capability of AGC is calculated using the maximum anti-interference capability α2.

2. The method for evaluating the flexibility of a power system considering the penetration rate of renewable energy according to claim 1, characterized in that: The mathematical formula of AGC nonlinear model is: Where x∈R n , u∈R m , w∈R l are state variables, control variables and disturbance variables respectively, represents the derivative of x, A, B, E are the state matrix, control matrix and disturbance matrix respectively, F is the linear feedback matrix, σ(·) is the saturation function, A, B, F contain the new energy penetration rate; The AGC attraction domain estimation ellipsoid Ω(P1) = {x0∈R n :x T P1x≤1}: x0 is the initial state. Constraint (a) in equation (2) introduces the shape reference set X R , X R is a specified bounded convex set. The maximum attraction domain estimate is obtained by optimizing the parameter α1. When α1 is larger, the attraction domain estimate ellipsoid Ω(P1) is larger. Constraints (b) and (c) are sufficient conditions for the attraction domain estimate ellipsoid Ω(P1) to satisfy the shrinkage invariance. P1 is a positive definite matrix, H is an auxiliary matrix, and I m is the m-order identity matrix, D i is a diagonal matrix with diagonal elements of 0 or 1, D i - =I m -D i , for a square matrix S, He(S)=S+S T , α1 is a positive real number and satisfies α1X R ={α1x:x∈X R }, function L(H)={x∈R n :||H x || ∞ ≤1} means H x Unsaturated areas.

3. The method for evaluating the flexibility of a power system considering the penetration rate of renewable energy according to claim 1, characterized in that: The mathematical formula of AGC nonlinear model is: Where x∈R n , u∈R m , w∈R l are state variables, control variables and disturbance variables respectively, represents the derivative of x, σ(·) is the saturation function, A, B, E are the state matrix, control matrix and disturbance matrix respectively, F is the linear feedback matrix, and A, B, F include the new energy penetration rate; The maximum anti-interference capability α2 of AGC is calculated according to the following formula: Where η is a given positive real number, and the global maximum value of α2 is obtained by scanning from (0,∞); Ω(P2) is the attraction domain ellipsoid considering the system perturbation w, w T w≤α2, P2 is a positive definite matrix, H is an auxiliary matrix, D i is a diagonal matrix with diagonal elements of 0 or 1, D i - =I m -D i , I m is the unit matrix of order m. For a square matrix S, He(S) = S + S T , function L(H)={x∈R n :||H x || ∞ ≤1} means H x Unsaturated areas.

4. The method for evaluating the flexibility of a power system considering the penetration rate of renewable energy according to claim 3 is characterized in that: The flexibility supply capability of AGC includes the maximum net load fluctuation value allowed to be connected to AGC |ΔP L |, where 5. The method for evaluating the flexibility of a power system considering the penetration rate of renewable energy according to claim 1, characterized in that: The estimated ellipsoid of the AGC attraction domain is the stable domain. The new energy penetration rate is updated, and the stable domain of the power system AGC considering the power supply flexibility constraint under different new energy penetration rates and the absolute value of the maximum net load fluctuation allowed to be connected |ΔP are calculated. L |.

6. A power system flexibility assessment device considering the penetration rate of new energy sources, characterized in that: include: The AGC nonlinear model with flexibility constraints is updated according to the given new energy penetration rate; A stable domain calculation module is configured to: calculate the AGC attraction domain estimation ellipsoid Ω(P1) based on the updated AGC nonlinear model using an attraction domain estimation method; The flexibility supply capacity calculation module is configured to calculate the maximum anti-interference capacity α2 of the AGC based on the updated AGC nonlinear model, and calculate the flexibility supply capacity of the AGC through the maximum anti-interference capacity α2.

7. The power system flexibility assessment device considering the penetration rate of new energy sources according to claim 6 is characterized in that: The mathematical formula of AGC nonlinear model is: Where x∈R n , u∈R m , w∈R l are state variables, control variables and disturbance variables respectively, represents the derivative of x, σ(·) is the saturation function, A, B, E are the state matrix, control matrix and disturbance matrix respectively, F is the linear feedback matrix, and A, B, F include the new energy penetration rate; The AGC attraction domain estimation ellipsoid Ω(P1) = {x0∈R n :x T P1x≤1}: x0 is the initial state. Constraint (a) in equation (2) introduces the shape reference set X R , X R is a specified bounded convex set. The maximum attraction domain estimate is obtained by optimizing the parameter α1. When α1 is larger, the attraction domain estimate ellipsoid Ω(P1) is larger. Constraints (b) and (c) are sufficient conditions for the attraction domain estimate ellipsoid Ω(P1) to satisfy the shrinkage invariance. P1 is a positive definite matrix, H is an auxiliary matrix, and I m is the m-order identity matrix, D i is a diagonal matrix with diagonal elements of 0 or 1, D i - =I m -D i , for a square matrix S, He(S)=S+S T , α1 is a positive real number and satisfies α1X R ={α1x:x∈X R }, function L(H)={x∈R n :||H x || ∞ ≤1} means H x Unsaturated areas.

8. The power system flexibility assessment device considering the penetration rate of new energy sources according to claim 6 is characterized in that: The mathematical formula of AGC nonlinear model is: Where x∈R n , u∈R m , w∈R l are state variables, control variables and disturbance variables respectively, represents the derivative of x, σ(·) is the saturation function, A, B, E are the state matrix, control matrix and disturbance matrix respectively, F is the linear feedback matrix, and A, B, F include the new energy penetration rate; The maximum anti-interference capability α2 is calculated according to the following formula: Where η is a given positive real number, and the global maximum value of α2 is obtained by scanning from (0,∞); Ω(P2) is the attraction domain ellipsoid considering the system perturbation w, w T w≤α2, P2 is a positive definite matrix, H is an auxiliary matrix, D i is a diagonal matrix with diagonal elements of 0 or 1, D i - =I m -D i , I m is the unit matrix of order m. For a square matrix S, He(S) = S + S T , function L(H)={x∈R n :||H x || ∞ ≤1} means H x Unsaturated areas.

9. The power system flexibility assessment device considering the penetration rate of new energy sources according to claim 8, characterized in that: The flexibility supply capability of AGC includes the maximum net load fluctuation value allowed to be connected to AGC |ΔP L |, where 10. The power system flexibility assessment device considering the penetration rate of new energy sources according to claim 6, characterized in that: The estimated ellipsoid of the AGC attraction domain is the stable domain. The new energy penetration rate is updated, and the stable domain of the power system AGC considering the power supply flexibility constraint under different new energy penetration rates and the absolute value of the maximum net load fluctuation allowed to be connected |ΔP are calculated. L |.

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