A method and device for calculating the access capacity of new energy in a regional power grid

Abstract

The application discloses a kind of regional power grid new energy access capacity calculation method and device, comprising: obtaining power grid new energy line transmission power data and power grid unit data;According to the power grid line transmission power data, section transmission power safety margin index and line transmission safety margin index are calculated;According to the power grid unit data and new energy access capacity, inertia safety margin index is constructed;According to the section transmission power safety margin index, line transmission safety margin index and inertia safety margin index, new energy access capacity target function is constructed;Solving the new energy access capacity target function, the best new energy access capacity is obtained.The influence of newly added new energy capacity on original power grid system is considered from three aspects of section transmission power safety, line transmission safety and inertia safety, and the best new energy access capacity can be obtained under the condition of ensuring safe operation of power grid system.

Description

Technical Field

[0001] This invention relates to the field of power system planning technology, and in particular to a method and apparatus for calculating the capacity of new energy access in a regional power grid. Background Technology

[0002] The installed capacity of new energy sources in the power system is gradually increasing, and their proportion of installed capacity is constantly rising, gradually becoming the third largest power source in the power grid. However, the output of new energy sources such as wind and solar power is random, volatile, and has anti-peak-shaving characteristics. The large-scale integration of new energy sources will bring the following problems:

[0003] I. The pressure on power grid peak regulation has increased significantly. Due to constraints such as large load peak-valley differences, poor overall adjustability of hydropower, and the anti-peak regulation characteristics of new energy sources, the pressure on power grid peak regulation is enormous. In the future, the amount of power curtailed for peak regulation may increase significantly due to the high proportion of new energy sources and the access of power from outside the region.

[0004] Second, the power system is showing a clear trend of power electronics and the interactive effects of large-scale grid integration, making grid operation more complex and significantly increasing the risks to safe and stable operation. The continuous replacement of conventional power sources by new energy sources and external DC power via power electronic interfaces will further deteriorate the grid's resilience to disturbances. Insufficient regulation capacity of new energy units leads to a continuous decline in system frequency and voltage support capabilities, resulting in a faster frequency drop under fault impacts.

[0005] Third, current methods for verifying the capacity of the power grid to add new renewable energy sources mainly rely on production time-series simulation software and static safety and stability calculations. However, these methods lack consideration for the safe and stable operation of the power grid after large-scale renewable energy integration and lack a systematic evaluation method, failing to guide the scientific allocation and layout of renewable energy from a safety and stability perspective. Therefore, there is an urgent need to research methods for calculating renewable energy absorption capacity that take into account safety and stability constraints. Summary of the Invention

[0006] The technical problem to be solved by the present invention is to provide a method and apparatus for calculating the access capacity of new energy sources in a regional power grid, which realizes the calculation of the access capacity of new energy sources while taking into account the security of the power grid system.

[0007] To solve the above-mentioned technical problems, the technical solution adopted by the present invention is as follows:

[0008] A method for calculating the renewable energy access capacity of a regional power grid includes:

[0009] Acquire power transmission data of new energy power lines and power grid unit data;

[0010] The cross-sectional transmission power safety margin index and the line transmission safety margin index are calculated based on the power transmission power data of the power grid lines.

[0011] The inertia safety margin index is constructed based on the power grid unit data and the new energy access capacity.

[0012] Based on the cross-sectional transmission power safety margin index, the line transmission safety margin index, and the inertia safety margin index, a new energy access capacity objective function is constructed.

[0013] Solve the objective function for the new energy access capacity to obtain the optimal new energy access capacity.

[0014] To solve the above-mentioned technical problems, another technical solution adopted by the present invention is as follows:

[0015] A regional power grid renewable energy access capacity calculation device includes a memory, a processor, and a computer program stored in the memory and executable on the processor. When the processor executes the computer program, it implements the various steps of the aforementioned regional power grid renewable energy access capacity calculation method.

[0016] The beneficial effects of this invention are as follows: Based on the power transmission data of new energy power lines, power grid unit data, and new energy access capacity, the safety margin index of cross-sectional power transmission, the safety margin index of line transmission, and the safety margin index of inertia are obtained respectively. The three indices are then integrated to obtain the objective function of new energy access capacity. Finally, the optimal new energy access capacity is obtained by solving the objective function of new energy access capacity. At the same time, the impact of the new energy capacity on the original power grid system is considered from the three aspects of cross-sectional power transmission safety, line transmission safety, and inertia safety. The optimal new energy access capacity can be obtained while ensuring the safe operation of the power grid system. Attached Figure Description

[0017] Figure 1 This is a flowchart illustrating the steps of a method for calculating the access capacity of new energy sources in a regional power grid according to an embodiment of the present invention.

[0018] Figure 2 This is a schematic diagram of the 500kV and 220kV interconnection lines of the regional power grid in a method for calculating the access capacity of new energy sources in a regional power grid according to an embodiment of the present invention.

[0019] Figure 3 This is a schematic diagram of the structure of a regional power grid new energy access capacity calculation device in an embodiment of the present invention. Detailed Implementation

[0020] To explain in detail the technical content, objectives, and effects of the present invention, the following description is provided in conjunction with the embodiments and accompanying drawings.

[0021] Please refer to Figure 1 A method for calculating the capacity of new energy access in a regional power grid, comprising:

[0022] Acquire power transmission data of new energy power lines and power grid unit data;

[0023] The cross-sectional transmission power safety margin index and the line transmission safety margin index are calculated based on the power transmission power data of the power grid lines.

[0024] The inertia safety margin index is constructed based on the power grid unit data and the new energy access capacity.

[0025] Based on the cross-sectional transmission power safety margin index, the line transmission safety margin index, and the inertia safety margin index, a new energy access capacity objective function is constructed.

[0026] Solve the objective function for the new energy access capacity to obtain the optimal new energy access capacity.

[0027] As can be seen from the above description, the beneficial effects of the present invention are as follows: Based on the power transmission data of new energy power lines, power grid unit data, and new energy access capacity, the safety margin index of cross-sectional power transmission, the safety margin index of line transmission, and the safety margin index of inertia are obtained respectively. Then, the three indices are integrated to obtain the objective function of new energy access capacity. Finally, the optimal new energy access capacity is obtained by solving the objective function of new energy access capacity. At the same time, the impact of the new energy capacity on the original power grid system is considered from the three aspects of cross-sectional power transmission safety, line transmission safety, and inertia safety. The optimal new energy access capacity can be obtained while ensuring the safe operation of the power grid system.

[0028] Furthermore, the power transmission data of the new energy power grid lines includes the line's maximum transmission capacity and the transmission power of the lines in each section;

[0029] The calculation of the cross-sectional transmission power safety margin index and the line transmission safety margin index based on the power transmission power data of the power grid line includes:

[0030] The control power of the new energy transmission section is calculated based on the maximum transmission capacity of the line.

[0031] The safety margin index of the transmission power of the new energy transmission section is calculated based on the control power of the new energy transmission section and the transmission power of the lines in each section.

[0032] The safety margin index of the line is calculated based on the line's maximum transmission capacity and the transmission power of the line in each section.

[0033] As described above, the line transmission safety margin index is obtained based on the line's maximum transmission capacity and the transmission power of the line in each section. The section transmission power safety margin index is obtained after obtaining the control power of the new energy transmission section based on the line's maximum transmission capacity. That is, the access capacity of new energy is limited under the condition of considering the line with the maximum transmission capacity to ensure the safety of the power grid system.

[0034] Furthermore, the safety margin index for the transmission line is as follows:

[0035]

[0036] In the formula, α represents the safety margin index of the transmission line; P i,line W represents the power of the i-th transmitting line. i,max This represents the maximum transmission capacity of the i-th outgoing line;

[0037] The safety margin index for the cross-sectional power transmission is:

[0038]

[0039]

[0040] In the formula, β k P represents the safety margin index of the transmission power at the k-th cross-section; k,i,line P represents the transmission power of the i-th line in the k-th cross-section; k,control W represents the control power output of the k-th section of the renewable energy transmission line; n represents the number of lines constituting the k-th section of the renewable energy transmission line. k,i,max This represents the maximum transmission capacity of the i-th line in the k-th cross-section; max{W k,1,max ,…,W k,i,max ,…,W k,n,max} represents the maximum transmission capacity of a single line among the n outgoing lines in this cross section.

[0041] As described above, the calculation method for the control power of the new energy transmission section is obtained under the condition of N-1 lines with the maximum transmission capacity, and the safety margin index of the transmission power of the section is defined to ensure the safety of the power grid system line transmission.

[0042] Furthermore, the power grid unit data includes the inertial time constant, capacity and status of conventional units, existing renewable energy installed capacity, renewable energy virtual inertia control proportional coefficient and safety constant;

[0043] Based on the power grid unit data and the new energy access capacity, the inertia safety margin indicators are constructed as follows:

[0044] The equivalent inertial time constant of the existing power grid system is calculated based on the inertial time constant, capacity, and status of the conventional generating units and the existing installed capacity of new energy sources.

[0045] The additional new energy inertia support amount is constructed based on the new energy virtual inertia control ratio coefficient and the new energy access capacity.

[0046] The equivalent inertial time constant of the future power grid system is constructed based on the inertial time constant, capacity, and status of the conventional generating units, the existing installed capacity of new energy sources, and the capacity of new energy access.

[0047] The inertia safety margin index is constructed based on the equivalent inertia time constant of the power grid system, the inertia support of newly added new energy sources, the equivalent inertia time constant of the future power grid system, and the safety constant.

[0048] As described above, by using power grid unit data, the equivalent inertial time constant of the power grid system, the inertial support of newly added renewable energy sources, and the equivalent inertial time constant of the future power grid system can be obtained. This accurately describes the relationship and changes between the old power grid system and the power grid system after the addition of renewable energy sources, thus ensuring the safety of the power grid system.

[0049] Furthermore, the calculation of the equivalent inertial time constant of the existing power grid system based on the inertial time constant, capacity, and status of the conventional generating units and the existing installed capacity of new energy sources includes:

[0050]

[0051] In the formula, H equal H represents the equivalent inertial time constant of the existing power grid system; l S represents the inertial time constant of the l-th conventional generating unit within the regional power grid. l x represents the capacity of the l-th conventional generating unit within the regional power grid. l Indicates the operating status of the l-th conventional unit, x l =1 indicates that the conventional unit is in the powered-on state, x l =0 indicates that the conventional unit is in the shutdown state; S RES,N This indicates the existing installed capacity of new energy sources.

[0052] As described above, after obtaining the above formula based on the inertial time constant, capacity, and status of conventional generating units and the existing installed capacity of new energy sources, the minimum start-up mode of the regional power grid can be obtained based on the power grid operation mode data. The equivalent inertial time constant of the system under the minimum start-up mode can be calculated based on the above formula to evaluate the stability of the system.

[0053] Furthermore, the step of constructing the additional new energy inertia support amount based on the new energy virtual inertia control ratio coefficient and the new energy access capacity includes:

[0054]

[0055] In the formula, H inertial Indicates the amount of new energy source inertia support; K inertia l represents the proportional coefficient for virtual inertia control of new energy sources; ΔS RES This indicates the newly added installed capacity of new energy sources.

[0056] As can be seen from the above description, parameters such as the newly added new energy installed capacity and the new energy virtual inertia control ratio coefficient can accurately describe the virtual inertia support that the newly added new energy units can provide to the system in the future.

[0057] Furthermore, the process of constructing the equivalent inertial time constant of the future power grid system based on the inertial time constant, capacity, and status of the conventional generating units, the existing installed capacity of new energy sources, and the capacity of new energy access includes:

[0058]

[0059] In the formula, H' equal H represents the equivalent inertial time constant of the future power grid system; l S represents the inertial time constant of the l-th conventional generating unit within the regional power grid. l x represents the capacity of the l-th conventional generating unit within the regional power grid. l Indicates the operating status of the l-th conventional unit; S RES,N Indicates the existing installed capacity of new energy sources; ΔS RES This indicates the newly added installed capacity of new energy sources.

[0060] As described above, the impact of new renewable energy capacity on the equivalent inertial time constant of the future power grid system can be accurately described by the inertial time constant, capacity, and operating status of conventional generating units in the power grid, as well as the existing renewable energy installed capacity and the new renewable energy installed capacity.

[0061] Furthermore, the inertia safety margin index, constructed based on the equivalent inertia time constant of the power grid system, the inertia support of newly added new energy sources, the equivalent inertia time constant of the future power grid system, and the safety constant, includes:

[0062]

[0063] In the formula, δ represents the inertia safety margin index; H equal H' represents the equivalent inertial time constant of the existing power grid system. equal H represents the equivalent inertial time constant of the future power grid system;inertial This represents the amount of newly added new energy inertia support; min{H min ,3} represents the safety constant.

[0064] As described above, the inertia safety margin index is obtained by using the equivalent inertia time constant of the power grid system, the inertia support of new renewable energy sources, the equivalent inertia time constant of the future power grid system, and the safety constant. That is, the impact of new renewable energy sources on the original power grid system is considered on the basis of the safety constant.

[0065] Furthermore, the objective function for constructing the new energy access capacity based on the cross-sectional transmission power safety margin index, the line transmission safety margin index, and the inertia safety margin index includes:

[0066] ΔS β,RES =min{ΔS k,RES (β k =0)}k∈(1,N);

[0067]

[0068] F=min(ΔS β,RES ,ΔS H,RES );

[0069] In the formula, ΔS β,RES This represents the increased capacity of new energy sources when the cross-sectional transmission power safety margin index is 0; β k ΔS represents the safety margin index of the transmission power at the k-th cross-section; k,RES This represents the increase in new energy capacity when the safety margin index of the transmission power at the k-th cross-section is 0; min{ΔS k,RES (β k =0)} represents the minimum value among the increased capacity of new energy sources, and N represents the number of cross sections; ΔS H,RES This represents the increased capacity of new energy sources when the inertia safety margin index is 0.

[0070] As described above, by calculating the increased capacity of renewable energy when the transmission power safety margin index of a section is 0, the increased capacity of renewable energy when the transmission power safety margin index of the kth section is 0, and the increased capacity of renewable energy when the inertia safety margin index is 0, the power grid system can operate safely after adding renewable energy capacity under different conditions.

[0071] Another embodiment of the present invention provides a regional power grid renewable energy access capacity calculation device, including a memory, a processor, and a computer program stored in the memory and executable on the processor. When the processor executes the computer program, it implements the various steps in the regional power grid renewable energy access capacity calculation method described above.

[0072] The method and apparatus for calculating the renewable energy access capacity of a regional power grid provided by this invention can be applied to scenarios where renewable energy is connected to the power grid system to calculate the renewable energy access capacity of the regional power grid. The following is a detailed description of the specific implementation methods:

[0073] Example 1

[0074] Please refer to Figure 1 A method for calculating the capacity of new energy access in a regional power grid, comprising:

[0075] S1. Acquire power transmission data of new energy power grid lines and power grid unit data; wherein, the power transmission data of new energy power grid lines includes the line's maximum transmission capacity and the transmission power of the lines in each section; the power grid unit data includes the inertial time constant, capacity and status of conventional units, existing new energy installed capacity, new energy virtual inertia control proportional coefficient and safety constant; at the same time, other relevant data of the power grid can also be acquired to construct or calculate different indicators and objective functions.

[0076] S2. Based on the power transmission data of the power grid lines, calculate the safety margin index of the transmission power at the cross-section and the safety margin index of the transmission line; define the safety margin index of the transmission line by analyzing the maximum transmission capacity of the line; simultaneously, considering the case of N-1 lines with the maximum transmission capacity, give the calculation method of the control power of the new energy transmission section, and define the safety margin index of the transmission power at the cross-section, specifically:

[0077] S21. Calculate the control power of the new energy transmission section based on the maximum transmission capacity of the line.

[0078] Wherein, the maximum transmission capacity W of the line max As shown in the following formula:

[0079]

[0080] In the formula, U e This is the rated voltage, which can be confirmed according to the voltage level; I max The continuous allowable current (kA) for the conductor can be obtained according to the requirements of the power grid equipment; The line power factor is typically taken as 0.95; K is the temperature correction factor for the line transmission capacity, with typical values ​​obtained from the design manual.

[0081] Typically, a region has multiple renewable energy transmission lines. Therefore, considering the maximum transmission capacity of line N-1, the control power of the renewable energy transmission section is as follows:

[0082]

[0083] In the formula, P k,controlW represents the control power output of the k-th section of the renewable energy transmission line; n represents the number of lines constituting the k-th section of the renewable energy transmission line. k,i,max This represents the maximum transmission capacity of the i-th line in the k-th cross-section; max{W k,1,max ,…,W k,i,max ,…,W k,n,max} represents the maximum transmission capacity of a single line among the n outgoing lines in this cross-section;

[0084] S22. Based on the control power of the new energy transmission section and the transmission power of the lines in each section, the safety margin index of the transmission power of the section is calculated, specifically:

[0085]

[0086] In the formula, β k P represents the safety margin index of the transmission power at the k-th cross-section; k,i,line This represents the transmission power of the i-th line in the k-th cross-section;

[0087] S23. The transmission safety margin index of the line is calculated based on the line's maximum transmission capacity and the transmission power of the line in each section. In areas rich in renewable energy, renewable energy is usually considered to be transmitted through 220 kV and 500 kV lines. Therefore, the transmission safety margin index α is defined (this index value is to constrain the renewable energy access capacity and cannot make the margin index value less than 0), as shown in the following formula:

[0088]

[0089] In the formula, α represents the safety margin index of the transmission line; P i,line W represents the power of the i-th transmitting line. i,max This represents the maximum transmission capacity of the i-th sending line.

[0090] S3. Based on the power grid unit data and the new energy access capacity, an inertia safety margin index is constructed. Specifically, historical data from periods when new energy is transmitted to other regions are selected, and the new energy output coefficient is calculated considering a 95% confidence interval. Furthermore, based on the power grid operation mode and considering that future new energy unit operation can provide virtual inertia support and ensure the safe and stable operation of the system, an inertia safety margin index is defined.

[0091] S30, Determine the output of new energy sources;

[0092] The output of new energy sources is related to their installed capacity and output coefficient, as shown in the following formula:

[0093] P RES =λS RES (5)

[0094] In the formula, P RES Indicates new energy output; S RES Let represent the installed capacity of new energy; λ represent the power output coefficient of new energy; simultaneously, historical data of the time periods during which new energy is transmitted to other regions are selected to calculate the power output coefficient of new energy, and the coefficients are arranged from largest to smallest, as shown in the following formula:

[0095]

[0096] λ range ={λ1,…,λ j ,…,λ m}j∈(1,m); (7)

[0097] In the formula, λ j P represents the renewable energy output coefficient at the j-th historical data point in the region; j,RES S represents the renewable energy output value at the j-th historical data point in the region; j,RES λ represents the installed capacity of new energy sources corresponding to the j-th historical data point in this region; range This array represents the array of historical data where the output coefficients of new energy sources are arranged from largest to smallest, and m represents the number of historical data points.

[0098] Furthermore, considering a 95% confidence interval (typically used by power grid operators and planners based on experience), i.e., from λ... range Select the 0.95mth data point λ from the array. 0.95 This is used as the new energy output coefficient, therefore the new energy output is λ. 0.95 S RES ;

[0099] S31. Based on the inertial time constant, capacity, and status of the conventional generating units and the existing installed capacity of new energy sources, the equivalent inertial time constant of the existing power grid system is calculated. Specifically:

[0100]

[0101] In the formula, H equal H represents the equivalent inertial time constant of the existing power grid system; l S represents the inertial time constant of the l-th conventional generating unit within the regional power grid. l x represents the capacity of the l-th conventional generating unit within the regional power grid. l Indicates the operating status of the l-th conventional unit, x l =1 indicates that the conventional unit is in the powered-on state, x l =0 indicates that the conventional unit is in the shutdown state; S RES,NThis represents the existing installed capacity of new energy sources. Simultaneously, based on the grid operation mode, the minimum operating mode of the regional grid can be obtained. Then, the equivalent inertial time constant H of the system under the minimum operating mode can be calculated using the above formula. min ;

[0102] S32. Based on the new energy virtual inertia control ratio coefficient and the new energy access capacity, the additional new energy inertia support is constructed. Generally, when the system's equivalent inertia time constant H ≥ 4, the system is considered a strong inertia system; when the system's equivalent inertia time constant H ≤ 3, the system is a weak inertia system; when the system's inertia time constant 3 < H < 4, the system is a general inertia system. Therefore, considering the future development of new energy and the safe and stable operation of the system, with a system equivalent inertia time constant H ≥ 3, the future operation of new energy units can provide virtual inertia support for the system. The system inertia support is shown in the following formula:

[0103]

[0104] In the formula, H inertial Indicates the amount of new energy source inertia support; K inertial ΔS represents the proportional coefficient for virtual inertia control of new energy sources. RES This indicates the newly added installed capacity of new energy sources;

[0105] S33. Based on the inertial time constant, capacity, and status of the conventional generating units, the existing installed capacity of new energy sources, and the capacity of new energy access, the equivalent inertial time constant of the future power grid system is constructed. Specifically:

[0106]

[0107] In the formula, H′ equal This represents the equivalent inertial time constant of the future power grid system;

[0108] S34. Based on the equivalent inertia time constant of the power grid system, the inertia support of newly added new energy sources, the equivalent inertia time constant of the future power grid system, and the safety constant, the inertia safety margin index is constructed, specifically:

[0109]

[0110] In the formula, δ represents the inertia safety margin index; min{H min ,3} represents the minimum value of the system's equivalent inertial time constant under the minimum start-up mode and the minimum inertial time constant required for the system's safe and stable operation, taking into account the future development of new energy sources.

[0111] S4. Construct a new energy access capacity objective function based on the cross-sectional transmission power safety margin index, the line transmission safety margin index, and the inertia safety margin index.

[0112] S5. Solve the objective function for the new energy access capacity to obtain the optimal new energy access capacity;

[0113] The objective function for new energy access capacity includes:

[0114] ΔS β,RES =min{ΔS k,RES (β k =0)} k∈(1,N); (12)

[0115]

[0116] F=min(ΔS β,RES ,ΔS H,RES (14)

[0117] In the formula, ΔS β,RES This represents the increased capacity of new energy sources whose cross-sectional transmission power safety margin is set to 0 through power flow calculations; β k ΔS represents the safety margin index of the transmission power at the k-th cross-section; k,RES This represents the increase in capacity of new energy sources that, through power flow calculations, ensure the safety margin index of the transmission power at the k-th cross-section is 0; min{ΔS k,RES (β k =0)} represents the minimum value among the increased capacity of new energy sources, and N represents the number of cross sections; ΔS H,RES This represents the increased capacity of new energy sources when the inertia safety margin index is 0.

[0118] Example 2

[0119] The difference between this embodiment and Embodiment 1 is that it specifically defines the method for solving the objective function;

[0120] In this embodiment, the objective function can be solved using linear interpolation. Solving the objective function using linear interpolation can improve the solution speed. The specific steps are as follows:

[0121] First, the increased capacity of new energy sources when the safety margin index of the cross-sectional transmission power is 0 is obtained through BPA power flow calculation, namely:

[0122] P3=(η2P i,initial,1 -η1P i,initial,2 ) / (η2-η1); (15)

[0123] In the formula, P i,initial,1 and P i,initial,2The first and second initial values ​​for solving the increase in new energy using the linear interpolation method are: η1 and η2 are the safety margin index values ​​of the cross-sectional transmission power corresponding to the initial values. Usually, one of these two index values ​​is greater than 0 and the other is less than 0. Assuming that η1 is greater than 0, then η2 is less than 0; P3 represents the increase in new energy.

[0124] The specific calculation rule is as follows: using P3 as the increase in new energy, solve for the safety margin index of cross-sectional transmission power. If the calculated margin index value is less than 0, then let P3 = P i,initial,1 Otherwise, P3 = P i,initial,2 Then return to equation (15) to continue the calculation;

[0125] Since the convergence speed of the linear interpolation method slows down when approaching η=0, the numerical perturbation method can be used to quickly solve for the increase in new energy when η=0 based on the solution obtained by the linear interpolation method. Specifically:

[0126] The sensitivity of the safety margin index for cross-sectional power transmission after the I-th iteration of the perturbation value is set as follows:

[0127]

[0128] In the formula, a I For the change in new energy capacity τ I Sensitivity of the safety margin index for cross-sectional power transmission; η(ΔP) (I) ) represents the increase in new energy sources as ΔP (I) Safety margin index value of cross-sectional transmission power at that time; η(ΔP) (I) ,τ I ) indicates that in ΔP (I) Add perturbation τ to the basis I Safety margin index for cross-sectional transmission power;

[0129] Next, based on sensitivity a I Solve for η(ΔP) (I+1) The change in new energy capacity when ) = 0 is shown in equation (17):

[0130] η(ΔP (I+1) )=η(ΔP (I) )+a I Δp (I+1) (17)

[0131] In the formula, ΔP (I+1) Let η(ΔP) be the value of the solution for the (I+1)th iteration. (I+1) The change in load in the supply area is calculated by finding the change in load ΔP of the supply area when ΔP = 0. (I+1) :

[0132] ΔP (I+1) =ΔP (I) +Δp(I+1) (18)

[0133] Set the convergence criterion ε, and set ΔP (I+1) Substitute into the calculation η(ΔP) (I+1) ), and determine η(ΔP) (I+1) If the convergence condition is not met, return to equation (15) and recalculate until the convergence condition equation (19) is met:

[0134] η(ΔP (I+1) )<ε; (19)

[0135] The method in this example will be explained below with reference to a specific scenario:

[0136] Please refer to Figure 2 Taking a regional power grid as an example, under the 2025 mid-season operation mode, the regional power grid load is 1.35 million kilowatts, the installed capacity of wind power is 3.52 million kilowatts (output coefficient of 0.4), the installed capacity of photovoltaic power generation is 0.91 million kilowatts (output coefficient of 0.6), the installed capacity of small thermal power is 0.5 million kilowatts (output coefficient of 0.8), the installed capacity of small hydropower is 1.24 million kilowatts (output coefficient of 0.7), the installed capacity of large hydropower is 0.2 million kilowatts (the simultaneous output rate of large hydropower units is 0 under the mid-season operation mode), and the installed capacity of large thermal power is 2 million kilowatts (output coefficient of 0, thermal power units in this region are not in operation under the mid-season operation mode). The total installed capacity of the system reaches 7.92 million kilowatts, the installed capacity of new energy is 4.43 million kilowatts, and the proportion of new energy installed capacity is 55.93%.

[0137] Under normal circumstances, the 500 kV main transformer grid connection sections of the regional power grid are the grid connection sections of the main transformers of two 500 kV substations, and the 500 kV external interconnection lines are one circuit of 500 kV line ①, one circuit of 500 kV line ②, and one circuit of 500 kV line ③; the 220 kV external interconnection lines are three circuits of 220 kV section ①, one circuit of 220 kV section ②, one circuit of 220 kV section ③, one circuit of 220 kV section ④, one circuit of 220 kV section ⑤, and one circuit of 220 kV section ⑥.

[0138] Considering that the cross-section of the I-circuit conductor of 220kV section ① is relatively small, its continuous maximum transmission capacity is 235,000 kW. The transmission capacity of the main transformers of the two 500kV substations in the region is 1.5 million kW and 2.5 million kW respectively. Under normal conditions, considering that the transmission capacity of the I-circuit of 220kV section ① has reached its limit, it can be seen from the BPA power flow calculation analysis based on actual data that there is still a certain margin for the main transformers of the 500kV substations in the region to connect to the grid. The regional power grid can add 3.4 million kW of power output and 8.5 million kW of new energy installed capacity.

[0139] Table 1. Transmission power of main transformers in the 220kV section ① and the regional 500kV substation under normal operating conditions.

[0140]

[0141] At this point, the required new energy access capacity that satisfies the constraints is 8.5 million kilowatts.

[0142] The solution is based on the method in this embodiment: the system's new energy access capacity is calculated when the power of the control section is equal to the safety and stability control constraint under the condition that the system N-1 is satisfied; considering the III circuit N-1 of 220kV section ①, the main transformer N-1 of regional 500kV substation A, and the main transformer N-1 of regional 500kV substation B, the continuous limit transmission capacity of I circuit of 220kV section ① is 235 MW, the transmission capacity of the main transformer A of regional 500kV substation A is 800 MW, and the transmission capacity of the main transformer B of regional 500kV substation B is 1,500 MW;

[0143] According to the verification results, the first circuit of 220kV section ① is still the section that is first restricted. Therefore, considering the third circuit N-1 of 220kV section ①, the scale of new energy in the region can be calculated. Considering that the transmission capacity of the first circuit of 220kV section ① has reached its limit, the main transformer of the 500kV substation in the region still has a certain margin for grid connection. Through BPA power flow calculation and analysis, it can be seen that the region can add 2.1 million kilowatts of power output and 5.25 million kilowatts of new energy installed capacity (considering a new energy output coefficient of 5%).

[0144] Table 2.2 Transmission power of 20kV section ①, main transformer A (grid connection) of regional 500kV substation, and main transformer B (grid connection) under the III-N-1 configuration of 20kV line ①

[0145]

[0146]

[0147] At this point, the renewable energy capacity that meets the constraints is calculated to be 5.25 million kilowatts. Therefore, as shown above, under the given 2025 peak-season conditions, the maximum renewable energy capacity that can be connected to the regional power grid is 3.5 million kilowatts. It is evident that the calculation method proposed in this patent can provide guidance and engineering practice for renewable energy development and its integration.

[0148] Example 3

[0149] Please refer to Figure 3A regional power grid renewable energy access capacity calculation device includes a memory, a processor, and a computer program stored in the memory and executable on the processor. When the processor executes the computer program, it implements the various steps in the regional power grid renewable energy access capacity calculation method as described in Embodiments 1 and 2.

[0150] In summary, the present invention provides a method and apparatus for calculating the renewable energy access capacity of a regional power grid. Based on the power transmission data of renewable energy lines, power generation data, and renewable energy access capacity, the method obtains the safety margin index of cross-sectional power transmission, the safety margin index of line transmission, and the safety margin index of inertia. The three indices are then integrated to obtain the objective function of renewable energy access capacity. Finally, the optimal renewable energy access capacity is obtained by solving the objective function. At the same time, the method considers the impact of the new renewable energy capacity on the original power grid system from the three aspects of cross-sectional power transmission safety, line transmission safety, and inertia safety, and can obtain the optimal renewable energy access capacity while ensuring the safe operation of the power grid system.

[0151] The above description is merely an embodiment of the present invention and does not limit the patent scope of the present invention. Any equivalent modifications made based on the content of the present invention specification and drawings, or direct or indirect applications in related technical fields, are similarly included within the patent protection scope of the present invention.

Claims

1. A method for calculating the capacity of new energy access in a regional power grid, characterized in that, include: Acquire power transmission data of new energy power lines and power grid unit data; The cross-sectional transmission power safety margin index and the line transmission safety margin index are calculated based on the power transmission power data of the new energy power transmission lines in the power grid. The inertia safety margin index is constructed based on the power grid unit data and the new energy access capacity. Based on the cross-sectional power transmission safety margin index and the inertia safety margin index, a new energy access capacity objective function is constructed. Solve the objective function for the new energy access capacity to obtain the optimal new energy access capacity; The grid unit data includes the inertial time constant, capacity and status of conventional units, existing renewable energy installed capacity, renewable energy virtual inertia control proportional coefficient and safety constant; Based on the power grid unit data and the new energy access capacity, the inertia safety margin indicators are constructed as follows: The equivalent inertial time constant of the existing power grid system is calculated based on the inertial time constant, capacity, and status of the conventional generating units and the existing installed capacity of new energy sources. The additional new energy inertia support amount is constructed based on the new energy virtual inertia control ratio coefficient and the new energy access capacity. The equivalent inertial time constant of the future power grid system is constructed based on the inertial time constant, capacity, and status of the conventional generating units, the existing installed capacity of new energy sources, and the capacity of new energy access. The inertia safety margin index is constructed based on the equivalent inertia time constant of the power grid system, the inertia support of newly added new energy sources, the equivalent inertia time constant of the future power grid system, and the safety constant. The equivalent inertial time constant of the existing power grid system calculated based on the inertial time constant, capacity, and status of the conventional generating units and the existing installed capacity of new energy sources includes: ； In the formula, This represents the equivalent inertial time constant of the existing power grid system; Indicates the first in the regional power grid l The inertial time constant of a conventional unit, Indicates the first in the regional power grid l The capacity of a conventional unit, Indicates the first l The operating status of a conventional generating unit. This indicates that the conventional generating unit is in the powered-on state. This indicates that the conventional generating unit is in a shutdown state; This indicates the existing installed capacity of new energy sources; The additional new energy inertia support amount obtained by constructing the new energy virtual inertia control ratio coefficient and new energy access capacity includes: ； In the formula, This indicates the amount of new energy source inertia support; This represents the proportional coefficient for virtual inertia control of new energy sources. This indicates the newly added installed capacity of new energy sources; The equivalent inertial time constant of the future power grid system, constructed based on the inertial time constant, capacity, and status of the conventional generating units, the existing installed capacity of new energy sources, and the capacity of new energy access, includes: ； In the formula, Indicates the capacity of new energy access; The inertia safety margin index, constructed based on the equivalent inertia time constant of the power grid system, the inertia support of newly added new energy sources, the equivalent inertia time constant of the future power grid system, and the safety constant, includes: ； In the formula, Indicates the safety margin of inertia; This represents the equivalent inertial time constant of the future power grid system; Represents the safety constant; The construction of the objective function for new energy access capacity based on the cross-sectional power transmission safety margin index and the inertia safety margin index includes: ； ； ； In the formula, This indicates the increased capacity of new energy sources when the safety margin index for cross-sectional transmission power is 0. This represents the safety margin index of the transmission power at the k-th cross section; This represents the increased capacity of new energy sources when the safety margin index of the transmission power at the k-th cross-section is 0. This represents the minimum value among the increased capacity from new energy sources. Indicates the number of cross sections; This represents the increased capacity of new energy sources when the inertia safety margin index is 0.

2. The method for calculating the capacity of new energy access in a regional power grid according to claim 1, characterized in that, The power transmission data of the new energy transmission lines in the power grid includes the maximum transmission capacity of the lines and the transmission power of the lines in each section; The calculation of the cross-sectional transmission power safety margin index and the line transmission safety margin index based on the power transmission power data of the new energy transmission lines of the power grid includes: The control power of the new energy transmission section is calculated based on the maximum transmission capacity of the line. The safety margin index of the transmission power of the new energy transmission section is calculated based on the control power of the new energy transmission section and the transmission power of the lines in each section. The safety margin index of the line is calculated based on the line's maximum transmission capacity and the transmission power of the line in each section.

3. The method for calculating the capacity of new energy access in a regional power grid according to claim 2, characterized in that, The safety margin index for the transmission line is: ； In the formula, This indicates the safety margin index for transmission lines; This represents the power of the i-th transmitting line. This represents the maximum transmission capacity of the i-th outgoing line; The safety margin index for the cross-sectional power transmission is: ； ； In the formula, This represents the safety margin index of the transmission power at the k-th cross section; This represents the transmission power of the i-th line in the k-th cross-section; This represents the control power delivered by the new energy source to the k-th cross-section; This represents the number of lines that constitute the k-th cross-section of the new energy transmission line. This represents the maximum transmission capacity of the i-th line in the k-th cross section; This represents the maximum transmission capacity of a single line among the n outgoing lines in this cross-section.

4. A regional power grid renewable energy access capacity calculation device, comprising a memory, a processor, and a computer program stored in the memory and executable on the processor, characterized in that, When the processor executes the computer program, it implements each step of the method for calculating the access capacity of new energy sources in a regional power grid as described in any one of claims 1-3.

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