Dynamic capacity increasing method for high-proportion new energy access of comprehensive energy storage equipment

Abstract

A high-proportion new energy access-oriented dynamic capacity increasing method for comprehensive energy storage equipment comprises the following steps: firstly, stabilizing a high-frequency change component in electric energy containing high-proportion new energy by using the energy storage equipment, and then analyzing harmonic characteristics of the transmitted electric energy after the high-frequency change component is stabilized; and then considering the influence of internal electric energy harmonic waves in the dynamic capacity increasing process, and finally obtaining a dynamic capacity increasing result oriented to high-proportion new energy access. By arranging the hybrid energy storage device, the high-frequency component in the input electric energy is stabilized, thermal instability caused by change of the high-frequency component is avoided, and safe operation of a line is guaranteed.

Description

Technical Field

[0001] The present invention belongs to the field of new energy, and in particular relates to a dynamic capacity expansion method for integrated energy storage equipment facing high-proportion new energy access. Background Art

[0002] Dynamic capacity expansion refers to installing online detection devices on transmission lines to monitor the conductor status (conductor temperature, tension, sag, etc.) and environmental conditions (ambient temperature, sunshine and wind speed, etc.). Under the premise of not exceeding the provisions of current technical regulations, the maximum allowable current carrying capacity of the conductor is calculated based on the Morgan current carrying capacity model, etc., making full use of the objectively existing implicit capacity of the line and improving the actual transmission capacity of the transmission line. It is very practical.

[0003] However, the existing dynamic capacity expansion technology does not take into account the characteristics of the system after a high proportion of new energy is connected, such as a high proportion of high-frequency changing components, high harmonic content, and strong intermittent fluctuations. Summary of the invention

[0004] The technical problem to be solved by the present invention is to provide a dynamic capacity expansion method for integrated energy storage equipment for high-proportion new energy access. By equipping hybrid energy storage equipment, the high-frequency components in the input electric energy are smoothed to avoid thermal instability caused by changes in high-frequency components, thereby ensuring safe operation of the line.

[0005] In order to solve the above technical problems, the technical solution adopted by the present invention is: A dynamic capacity expansion method for integrated energy storage equipment facing high proportion of new energy access includes the following steps: Use energy storage equipment to smooth out the high-frequency variation of electric energy after a high proportion of new energy is connected; Analyze the harmonic characteristics of input power after smoothing the fluctuation of renewable energy, and consider the impact of harmonics during dynamic capacity expansion; The dynamic capacity expansion results for high proportion of new energy access are obtained. Preferably, the steps of using energy storage equipment to smooth the high-frequency variation components of electric energy after a high proportion of new energy is connected are: S1.1. Analyze the input power data of high-proportion renewable energy access by wavelet packet decomposition method and decompose it into high-frequency fluctuation part and low-frequency variation component; S1.2. Analyze the high-frequency components of historical data, determine the capacity of the energy storage system, and formulate a hybrid energy storage allocation strategy.

[0006] Preferably, the operation of S1.2 is: taking the number m of high frequency bands in the input power fluctuation component as the dividing point for energy storage power allocation; the allocation relationship satisfies equations (1)-(3): (1); (2); (3); Where: P wt (.) is the corresponding power after the input power is decomposed by wavelet packet and reconstructed in each frequency band; db 6 is the wavelet basis; 2 n is the frequency band interval; m is the number of high frequency bands; n is the number of decomposition layers; Represents the new energy input power; It represents the lower frequency part of the new energy input power; Represents the higher frequency portion of renewable energy input power.

[0007] Preferably, the harmonic characteristics of the input electric energy after smoothing the fluctuation of new energy are analyzed, and the influence of harmonics is considered in the dynamic capacity increase process, and the steps are as follows: S2.1. Calculate the specific harmonic order and harmonic content of the input electric energy by Fourier decomposition method; S2.2. Calculate the AC resistance of the transmission line at each harmonic order.

[0008] Preferably, the calculation process of step S2.2 is as follows: S2.2.1. List the differential equations for solving the electric field vector inside the steel core aluminum stranded wire; S2.2.2. Solve the differential equations and obtain the vector solution of the differential equations: S2.2.3. Assuming that the total current in the conductor is 1, the theoretical AC resistance expression of the conductor can be obtained; S2.2.4. After obtaining the AC resistance at each harmonic order, the heating power of the transmission line resistance at each harmonic can be calculated.

[0009] Preferably, in step S2.2.1, the radius of the steel core inside the steel core aluminum stranded wire is R1, and the outer diameter of the wire is R2; since there are two kinds of materials used for the steel core aluminum stranded wire, the current density distribution inside the wire will suddenly change due to the stratification of the material conductivity and magnetic permeability; as shown in formula (4): (4); In the formula, m 1, s 1 is the electrical conductivity and magnetic permeability of the steel core, m 2, s 2 is the electrical conductivity and magnetic permeability of the aluminum wire, ω is the alternating frequency, E max is the total electric field strength vector inside the conductor, ris the radial direction coordinate variable in cylindrical coordinates, d is the differential symbol, j Is the imaginary number symbol.

[0010] Preferably, the solution process of step S2.2.2 is as follows: (5); In the formula c 1, c 2 are the influence factors of two types of zero-order Bessel equations on the electric field intensity, J 0( k ) is the first kind of zero-order modified Bessel function, i is a positive integer, and its value is determined by the problem to be solved, Γ() is a special function in mathematics; The parameters in formula (5) can be calculated by formula (6): (6); In the formula I m is the current vector inside the wire, k 1 and k 2 refers to the coefficient calculated by the right-hand formula.

[0011] Preferably, the calculation process of step S2.2.3 is as follows: (7); From the formula, we can know that the AC resistance of steel core aluminum stranded wire is R ac It is determined by seven variables: the magnetic permeability, electrical conductivity, radius of the steel core, the magnetic permeability, electrical conductivity, thickness of the aluminum wire layer, and current frequency. After obtaining the AC resistance at each harmonic order, the resistance heating power of the transmission line at each harmonic can be calculated.

[0012] Preferably, the method for obtaining the dynamic capacity increase result for high proportion of new energy access is: Considering Joule heat, solar radiation heat, radiation heat dissipation and convection heat dissipation, the heat balance relationship of the transmission line can be listed as follows: (8); Where: Q r Q is the radiation heat dissipation power of steel core aluminum stranded wire; f The heat dissipation power of air convection; Q s I is the heat absorption power of the conductor when the sun shines on it; 2 R ac is the resistance heating power of the wire; It is worth noting that the resistance heating power includes not only the fundamental wave heating power, but also the harmonic heating power, as shown in formula (9): (9); In the formula,I 0, R ac0 is the fundamental current and fundamental AC resistance, i is the harmonic order; the transmission line current carrying capacity calculation formula is: (10); Finally, the dynamic capacity expansion result for high proportion of new energy access is obtained.

[0013] A dynamic capacity expansion system for a comprehensive energy storage device facing high-proportion new energy access, and a dynamic capacity expansion method for a comprehensive energy storage device facing high-proportion new energy access. The present invention can achieve the following beneficial effects: 1. By equipping hybrid energy storage equipment, the high-frequency components in the input electric energy are smoothed to avoid thermal instability caused by changes in high-frequency components and ensure safe operation of the line; 2. Consider the impact of harmonics on dynamic capacity expansion to make the calculation results more accurate and adapt to the high harmonic characteristics after a high proportion of new energy is connected. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] The present invention will be further described below in conjunction with the accompanying drawings and embodiments: Figure 1 It is a flow chart of the present invention; Figure 2 This is a system structure diagram of the dynamic capacity expansion method for high-proportion new energy access based on comprehensive energy storage equipment of the present invention. DETAILED DESCRIPTION

[0015] The preferred solution is Figure 1 to Figure 2 As shown in FIG. 1 , the dynamic capacity expansion method of the integrated energy storage device for high-proportion new energy access comprises the following steps: S1. Use energy storage equipment to smooth out the high-frequency variation of electric energy after a high proportion of new energy is connected; S1.1. The input power data of high-proportion renewable energy access are analyzed by wavelet packet decomposition method, and decomposed into high-frequency fluctuation part and low-frequency variation component.

[0016] The wavelet packet analysis method can not only decompose the low-frequency part of the signal, but also further decompose the high-frequency signal. When the active power fluctuation value DP of the decomposed low-frequency component meets the conditions, the decomposition is stopped. Otherwise, the number of decomposition layers needs to be increased until the active power fluctuation value corresponding to the low-frequency component meets the requirements.

[0017] S1.2. Analyze the high-frequency components of historical data, determine the capacity of the energy storage system, and formulate a hybrid energy storage allocation strategy. The specific steps are: The high-frequency segment number m in the input power fluctuation component is used as the dividing point for energy storage power allocation; the battery energy storage system has a low charge and discharge rate, and frequent charge and discharge will accelerate the attenuation and aging of the battery, so the lower frequency part P in the high-frequency ... battery energy storage system has a low charge and discharge rate, and the battery energy storage system has a low charge and discharge rate al to lithium batteries, which helps to extend their lifespan; at the same time, the higher frequency part P ah Distribute to supercapacitors to take advantage of their long cycle life; The distribution relationship satisfies equations (1)-(3): (1); (2); (3); Where: P wt (.) is the corresponding power after the input power is decomposed by wavelet packet and reconstructed in each frequency band; db 6 is the wavelet basis; 2 n is the frequency band interval; m is the number of high frequency bands; n is the number of decomposition layers; Represents the new energy input power; It represents the lower frequency part of the new energy input power; Represents the higher frequency portion of renewable energy input power.

[0018] S2. Analyze the harmonic characteristics of the transmitted power after smoothing the high-frequency variation components; consider the influence of internal power harmonics during dynamic capacity expansion; S2.1. The specific harmonic order and harmonic content of the input electrical energy are calculated by Fourier decomposition method.

[0019] S2.2. Calculate the AC resistance of the transmission line at each harmonic order; S2.2.1. List the differential equations for solving the electric field vector inside the steel core aluminum stranded wire; Assume that the radius of the steel core inside the steel core aluminum stranded wire is R1, and the outer diameter of the wire is R2; since the steel core aluminum stranded wire uses two kinds of materials, the current density distribution inside the wire will suddenly change due to the stratification of the material conductivity and magnetic permeability; as shown in formula (4): (4); In the formula, m 1, s 1 is the electrical conductivity and magnetic permeability of the steel core, m 2, s 2 is the electrical conductivity and magnetic permeability of the aluminum wire, ω is the alternating frequency, E max is the total electric field strength vector inside the conductor, ris the radial direction coordinate variable in cylindrical coordinates, d is the differential symbol, j Is the imaginary number symbol.

[0020] S2.2.2. Solve the differential equations and obtain the vector solution of the differential equations: The solution process is as follows: (5); In the formula c 1, c 2 are the influence factors of two types of zero-order Bessel equations on the electric field intensity, J 0( k ) is the first kind of zero-order modified Bessel function, i is a positive integer, and its value is determined by the problem to be solved, and Γ() is a special function in mathematics.

[0021] The parameters in formula (5) can be calculated by formula (6): (6); In the formula I m is the current vector inside the wire, k 1 and k 2 refers to the coefficient calculated by the right-hand formula.

[0022] S2.2.3. Assuming that the total current in the conductor is 1, the theoretical AC resistance expression of the conductor can be obtained: (7); From the formula, we can know that the AC resistance of steel core aluminum stranded wire is R ac It is determined by seven variables: magnetic permeability, electrical conductivity, radius of the steel core, magnetic permeability, electrical conductivity, thickness of the aluminum wire layer, and current frequency. After obtaining the AC resistance at each harmonic order, the resistance heating power of the transmission line at each harmonic can be calculated.

[0023] S2.2.4. After obtaining the AC resistance at each harmonic order, the heating power of the transmission line resistance at each harmonic can be calculated.

[0024] S3. The dynamic capacity expansion results for high proportion of new energy access are obtained: Considering Joule heat, solar radiation heat, radiation heat dissipation and convection heat dissipation, the heat balance relationship of the transmission line can be listed as follows: (8); Where: Q r Q is the radiation heat dissipation power of steel core aluminum stranded wire; f The heat dissipation power of air convection; Q s I is the heat absorption power of the conductor when the sun shines on it; 2 Rac is the resistance heating power of the wire; It is worth noting that the resistance heating power includes not only the fundamental wave heating power, but also the harmonic heating power, as shown in formula (9): (9); In the formula, I 0, R ac0 is the fundamental current and fundamental AC resistance, i is the harmonic order; the transmission line current carrying capacity calculation formula is: (10); The dynamic capacity expansion results for high proportion of new energy access are obtained.

[0025] A dynamic capacity expansion system for a comprehensive energy storage device facing high-proportion new energy access adopts the dynamic capacity expansion method for a comprehensive energy storage device facing high-proportion new energy access.

[0026] This method is applicable to the regional power grid where a high proportion of renewable energy (wind energy, photovoltaic power, etc.) is collected and sent out. After the high proportion of renewable energy (wind energy, photovoltaic power, etc.) is connected, the power output of renewable energy generation is unstable due to the intermittent and volatile nature of renewable energy, resulting in the power quality of the power grid being affected by high-frequency fluctuations, especially when the wind speed and light conditions change rapidly.

[0027] By implementing the above steps, the system can monitor and predict in real time the dynamic changes of the power grid under the condition of a high proportion of new energy access. First, a storage device of appropriate capacity is configured on the power input side, and the energy storage device is used to effectively smooth high-frequency fluctuations. Then, through harmonic analysis and thermal balance calculation, the real-time maximum allowable current carrying capacity of the transmission line is obtained, which provides decision-making support for the dispatching department to achieve dynamic capacity expansion and ensure the safe and stable operation of the transmission line.

[0028] The use of hybrid energy storage devices and dynamic capacity expansion methods can significantly improve the stability and dispatchability of the power grid, reduce energy waste, and improve the operating efficiency of the entire power system.

[0029] The above embodiments are only preferred technical solutions of the present invention and should not be regarded as limiting the present invention. The protection scope of the present invention shall be the technical solutions recorded in the claims, including equivalent replacement solutions of the technical features in the technical solutions recorded in the claims. That is, equivalent replacement improvements within this scope are also within the protection scope of the present invention.

Claims

1. A dynamic capacity expansion method for integrated energy storage equipment facing high proportion of new energy access, characterized in that The following steps are involved: Use energy storage equipment to smooth out the high-frequency variation of electric energy after a high proportion of new energy is connected; Analyze the harmonic characteristics of input power after smoothing the fluctuation of renewable energy, and consider the impact of harmonics during dynamic capacity expansion; The dynamic capacity expansion results for high proportion of new energy access are obtained.

2. The dynamic capacity expansion method for high-proportion new energy access of the comprehensive energy storage device according to claim 1 is characterized in that: The steps to use energy storage equipment to smooth the high-frequency variation components of electric energy after a high proportion of new energy is connected are: S1.

1. Analyze the input power data of high-proportion renewable energy access by wavelet packet decomposition method and decompose it into high-frequency fluctuation part and low-frequency variation component; S1.

2. Analyze the high-frequency components of historical data, determine the capacity of the energy storage system, and formulate a hybrid energy storage allocation strategy.

3. The dynamic capacity expansion method for high-proportion new energy access of the comprehensive energy storage device according to claim 2 is characterized in that: The operation of S1.2 is: the number m of high frequency bands in the input power fluctuation component is used as the dividing point for energy storage power allocation; the allocation relationship satisfies equations (1)-(3): (1)； (2)； (3)； Where: P wt (.) is the corresponding power after the input power is decomposed by wavelet packet and reconstructed in each frequency band; db 6 is the wavelet basis; 2 n is the frequency band interval; m is the number of high frequency bands; n is the number of decomposition layers; Represents the new energy input power; It represents the lower frequency part of the new energy input power; Represents the higher frequency portion of renewable energy input power.

4. The dynamic capacity expansion method for high-proportion new energy access of the comprehensive energy storage device according to claim 1 is characterized in that: Analyze the harmonic characteristics of the input power after smoothing the fluctuation of renewable energy, and consider the influence of harmonics in the dynamic capacity increase process. The steps are as follows: S2.

1. Calculate the specific harmonic order and harmonic content of the input electric energy by Fourier decomposition method; S2.

2. Calculate the AC resistance of the transmission line at each harmonic order.

5. The dynamic capacity expansion method for high-proportion new energy access of the comprehensive energy storage device according to claim 4 is characterized in that: The calculation process of step S2.2 is as follows: S2.2.

1. List the differential equations for solving the electric field vector inside the steel core aluminum stranded wire; S2.2.

2. Solve the differential equations and obtain the vector solution of the differential equations: S2.2.

3. Assuming that the total current in the conductor is 1, the theoretical AC resistance expression of the conductor can be obtained; S2.2.

4. After obtaining the AC resistance at each harmonic order, the heating power of the transmission line resistance at each harmonic can be calculated.

6. The dynamic capacity expansion method for high-proportion new energy access of the comprehensive energy storage device according to claim 5 is characterized in that: In step S2.2.1, the radius of the steel core inside the steel core aluminum stranded wire is assumed to be R1, and the outer diameter of the wire is assumed to be R2. Since there are two types of materials used for the steel core aluminum stranded wire, the current density distribution inside the wire will suddenly change due to the stratification of the material conductivity and magnetic permeability; as shown in formula (4): (4)； In the formula, m 1, s 1 is the electrical conductivity and magnetic permeability of the steel core, m 2, s 2 is the electrical conductivity and magnetic permeability of aluminum wire, is the alternating frequency, E max is the total electric field strength vector inside the conductor, r is the radial direction coordinate variable in cylindrical coordinates, d is the differential symbol, j Is the imaginary number symbol.

7. The dynamic capacity expansion method for high-proportion new energy access of the comprehensive energy storage device according to claim 5 is characterized in that: The solution process of step S2.2.2 is as follows: (5)； In the formula c 1, c 2 are the influence factors of two types of zero-order Bessel equations on the electric field intensity, J 0( k ) is the first kind of zero-order modified Bessel function, i is a positive integer, and its value is determined by the problem to be solved, Γ() is a special function in mathematics; The parameters in formula (5) can be calculated by formula (6): (6)； In the formula I m is the current vector inside the wire, k 1 and k 2 refers to the coefficient calculated by the right-hand formula.

8. The dynamic capacity expansion method for high-proportion new energy access of the comprehensive energy storage device according to claim 5 is characterized in that: The calculation process of step S2.2.3 is as follows: (7)； From the formula, we can know that the AC resistance of steel core aluminum stranded wire is R ac It is determined by seven variables: the magnetic permeability, electrical conductivity, radius of the steel core, the magnetic permeability, electrical conductivity, thickness of the aluminum wire layer, and current frequency. After obtaining the AC resistance at each harmonic order, the resistance heating power of the transmission line at each harmonic can be calculated.

9. The dynamic capacity expansion method for high-proportion new energy access of the comprehensive energy storage device according to claim 1 is characterized in that: The method to obtain the dynamic capacity increase result for high proportion of new energy access is: Considering Joule heat, solar radiation heat, radiation heat dissipation and convection heat dissipation, the heat balance relationship of the transmission line can be listed as follows: (8)； Where: Q r Q is the radiation heat dissipation power of steel core aluminum stranded wire; f The heat dissipation power of air convection; Q s I is the heat absorption power of the conductor when the sun shines on it; 2 R ac is the resistance heating power of the wire; It is worth noting that the resistance heating power includes not only the fundamental heating power, but also the harmonic heating power, as shown in formula (9): (9)； In the formula, I 0, R ac0 is the fundamental current and fundamental AC resistance, i is the harmonic order; the transmission line current carrying capacity calculation formula is: (10)； Finally, the dynamic capacity expansion result for high proportion of new energy access is obtained.

10. A dynamic capacity expansion system for integrated energy storage equipment with high proportion of new energy access, characterized by: A dynamic capacity expansion method for high-proportion new energy access of the comprehensive energy storage device according to any one of claims 1 to 9 is adopted.

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