220 kilovolt power transformation capacity demand evaluation method considering regional power grid irradiance

Abstract

The invention relates to a 220KV power transformation capacity demand evaluation method considering regional power grid irradiance, and relates to the technical field of power grids. According to the method, the power grid irradiance factor, the new energy development condition, the noon output coincidence rate of the regional distributed photovoltaic, the installation condition of the distributed photovoltaic and the regional 220-kilovolt capacity-load ratio are considered, and the regional 220-kilovolt power transformation capacity vacancy is obtained through calculation. Meanwhile, safe and stable operation and reliable power supply of the power grid are considered, the 220 kilovolt power transformation capacity needing to be increased is calculated, and a regional power grid 220 kilovolt power transformation capacity demand evaluation index is provided and used for evaluating the relation between the power transformation capacity lacked by each heavy load transformer substation and the whole regional 220 kilovolt power transformation capacity vacancy. The method provided by the invention can provide a theoretical analysis basis for determining whether the 220KV power transformation capacity is increased or not for power grid planners, and has very important significance for power grid development, safe and stable operation of the power grid and reliable power supply.

Description

Technical Field

[0001] The present application relates to the field of power grid technology, and in particular to a 220 kV substation capacity demand assessment method taking into account regional power grid irradiance. Background Art

[0002] Electricity has the advantages of being convenient, safe, efficient, and relatively environmentally friendly. Electricity substitution has always been a major trend in terminal consumption. With the rapid development of new energy and the further advancement of electricity substitution, the proportion of electricity in terminal consumption will gradually increase.

[0003] On the one hand, the penetration rate of distributed photovoltaics continues to increase, which will inevitably have an important impact on the planning, construction and development of power grids in order to ensure the safe and reliable operation of power grids and the quality of power. This puts forward new requirements for the power system's ability to connect new energy to the grid and disconnect power from the grid. In order to fully support the rapid increase in the proportion of electricity in terminal consumption, it is necessary to further analyze and evaluate the relevant substation capacity requirements to meet the needs of power grid-connected end users. On the other hand, considering the differences in the normal operating load rate of substations and the number and capacity of main transformers, it is necessary to analyze the main transformer capacity requirements required by substations when the main transformer N-1. Summary of the invention

[0004] The purpose of this application is to provide a 220 kV substation capacity demand assessment method that takes into account the regional power grid irradiance. This method can provide power grid planners with a theoretical analysis basis for whether the 220 kV substation capacity should be increased, which is of great significance to the development of the power grid and the safe and stable operation and reliable power supply of the power grid.

[0005] In order to achieve the above object, the present invention provides a 220 kV transformer capacity demand assessment method considering regional power grid irradiance, the method comprising:

[0006] S1: Get the annual average radiation energy of the analyzed area;

[0007] S2: Based on the annual average radiation energy, calculate the average annual power generation per square meter;

[0008] S3: Based on the average annual power generation per square meter, calculate the annual power generation of distributed photovoltaics in the analysis area;

[0009] S4: Based on the annual power generation of distributed photovoltaics in the analysis area, the maximum power value of distributed photovoltaics is calculated;

[0010] S5: Based on the maximum power value of distributed photovoltaics, calculate the output power of distributed photovoltaics in the midday mode;

[0011] S6: Calculate the 220 kV grid load based on the distributed photovoltaic output power in the midday mode;

[0012] S7: Calculate the 220 kV grid-connected transformer capacity based on the 220 kV grid supply load and the 220 kV grid planning technical guidelines;

[0013] S8: Calculate the substation capacity deficit in the analysis area based on the 220 kV grid-connected substation capacity;

[0014] S9: Calculate the load rate of the heavy-loaded 220 kV substation in the analysis area based on the heavy-load conditions of renewable energy on-grid and off-grid in each 220 kV substation in the analysis area;

[0015] S10: Based on the analysis of the load rate of the heavily loaded 220 kV substation in the regional power grid, calculate the additional substation capacity required;

[0016] S11: Based on the required additional transformer capacity of the substation, calculate the actual additional 220 kV transformer capacity;

[0017] S12: Based on the analysis of the regional transformer capacity shortage and the actual increase in 220 kV transformer capacity, the regional power grid 220 kV transformer capacity demand assessment index is calculated.

[0018] In an optional implementation, in S2, the average annual power generation per square meter is calculated as follows:

[0019]

[0020] Where W electric represents the average annual power generation per square meter in the analysis area, α represents the conversion efficiency of photovoltaic panels from radiation energy to electrical energy, W ave It represents the average annual radiation energy per square meter in the analysis area in the past five years.

[0021] In an optional implementation, in S3, the calculation method of the annual power generation of distributed photovoltaic power generation in the analysis area is as follows:

[0022] W annual,electric =W electric ·S PV,square ·η

[0023] In the formula, S PV,square W represents the area in the analysis area where distributed photovoltaics can be installed. annual,electric It represents the annual power generation of distributed photovoltaic in the analysis area, and η represents the conversion efficiency of distributed photovoltaic DC side component power after the inverter.

[0024] In an optional implementation, in S4, the maximum power value of the distributed photovoltaic is calculated as follows:

[0025]

[0026] Where P PV,N Indicates the maximum power value of distributed photovoltaic, T max Indicates the maximum utilization hours.

[0027] In an optional implementation, in S5, the distributed photovoltaic output power in the midday mode is calculated as follows:

[0028]

[0029] Where P PV,actual represents the output power of distributed photovoltaic power generation in the analysis area at noon, S PV，square，actual It represents the actual installed area of ​​distributed photovoltaic in the analysis area, and λ represents the average maximum simultaneous rate of photovoltaic output in the analysis area at noon in the past five years.

[0030] In an optional embodiment, in S6, the 220 kV grid supplies load P load，tuawork The calculation method is as follows:

[0031] P load，network =P load，region -P source -P load,user

[0032] P source =P PV，actual +P wind，actual +P conventional

[0033] Where P load，region represents the dispatching load in the analyzed area, P source Indicates the output power of power sources of 110 kV and below in the analysis area, P load,user P represents the load of large users in the analysis area; wind，actuat P represents the output power of wind turbines with a voltage of 110 kV or less in the analyzed area; conventional Indicates the output power of conventional power sources of 110 kV and below in the analysis area.

[0034] In an optional implementation, in S7, the 220 kV grid transformer capacity is calculated as follows:

[0035] 1.7P load,network ≤S require,trans,220kV ≤1.9P load,network

[0036] In the formula, S require，trans，220kV It indicates the substation capacity of the analyzed area that meets the technical requirements of 220 kV power grid planning, that is, the 220 kV off-grid substation capacity.

[0037] In an optional embodiment, in S8, the regional transformer capacity shortage ΔS is analyzed.trans，220kV The calculation method is as follows:

[0038] ΔS trans,220kV =S require,trans,220kV -S trans,220kV

[0039] In the formula, S trans，220kV It indicates the existing main transformer capacity of 220 kV substation in the analysis area.

[0040] In an optional implementation, S10 includes:

[0041] When the load rate of the heavy-load 220 kV substation in the analyzed area is greater than 100%, the substation needs to increase the substation capacity ΔS j，trans,capcity , as shown below:

[0042] ΔS j,trans,capcity =max{S j,1,trans ,…,S j,n,trans}

[0043] In the formula, S j,n,trans represents the capacity of the nth 220 kV main transformer in the jth 220 kV substation, and n represents the number of 220 kV main transformers in the jth substation;

[0044] In S11, the actual increase in 220 kV transformer capacity ΔS capacity,220kV As shown below:

[0045]

[0046] In the formula, ΔS capacity,220kV It represents the actual increase of 220 kV substation substation capacity, and m represents the number of 220 kV substations in the analysis area.

[0047] In an optional implementation, in S12, the regional power grid 220 kV transformer capacity demand evaluation index δ is calculated as shown in the following formula:

[0048]

[0049] This application takes into account the grid irradiance factor and the development of new energy, fully analyzes the regional distributed photovoltaic power generation rate at noon and the installed capacity of distributed photovoltaic power generation, and calculates the regional 220 kV substation capacity shortage based on the regional 220 kV capacity-load ratio. At the same time, considering the safe and stable operation and reliable power supply of the power grid, the load rate under the N-1 fault of the main transformer of the heavy-loaded 220 kV substation is analyzed, and the 220 kV substation capacity that needs to be increased is calculated by considering the load transfer of the lower-level power grid and the lack of stable control and removal of new energy. Finally, an evaluation index for the demand for 220 kV substation capacity of the regional power grid is proposed to evaluate the relationship between the substation capacity lacking in each heavy-load substation and the overall 220 kV substation capacity shortage in the region. The method proposed in this application can provide a theoretical analysis basis for power grid planners on whether the 220 kV substation capacity should be increased, which is of great significance to the development of the power grid and the safe, stable operation and reliable power supply of the power grid.

[0050] Other features and advantages of the present application will be described in detail in the subsequent specific implementation section. BRIEF DESCRIPTION OF THE DRAWINGS

[0051] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings required for use in the embodiments will be briefly introduced below. It should be understood that the following drawings only show certain embodiments of the present application and therefore should not be regarded as limiting the scope. For ordinary technicians in this field, other related drawings can be obtained based on these drawings without paying creative work.

[0052] Figure 1 A flow chart of a 220 kV substation capacity demand assessment method taking into account regional power grid irradiance provided in an embodiment of the present application. DETAILED DESCRIPTION

[0053] In order to make the purpose, technical scheme and advantages of the embodiments of the present application clearer, the technical scheme in the embodiments of the present application will be clearly and completely described below in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are part of the embodiments of the present application, rather than all of the embodiments. The components of the embodiments of the present application described and shown in the drawings here can be arranged and designed in various different configurations.

[0054] In the description of this application, it should be noted that the terms "inside", "outside", etc. indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings, or the orientation or positional relationship in which the product of the application is usually placed when in use, which is only for the convenience of describing this application and simplifying the description, and does not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on this application. In addition, the terms "first", "second", etc. are only used to distinguish the description, and cannot be understood as indicating or implying relative importance.

[0055] In the description of this application, it should also be noted that, unless otherwise clearly specified and limited, the terms "disposed" and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a direct connection, or an indirect connection through an intermediate medium, or it can be the internal communication of two elements. For ordinary technicians in this field, the specific meanings of the above terms in this application can be understood according to specific circumstances.

[0056] Please refer to Figure 1 This embodiment provides a 220 kV transformer capacity demand assessment method considering regional power grid irradiance (hereinafter referred to as: method), the method comprising the following steps:

[0057] S1: Get the annual average radiation energy of the analysis area.

[0058] Specifically, based on measured data, the huge energy potential of solar energy is analyzed. Based on historical statistical data, the daily cumulative radiation energy of the analysis area can be obtained. By accumulating the daily cumulative radiation energy, the annual radiation energy can be obtained. The average annual radiation energy of the analysis area in the past five years is analyzed to obtain the annual average radiation energy, as shown in the following formula:

[0059]

[0060] Where W ave It represents the average annual radiation energy per square meter in the analysis area in the past five years (MJ / m 2 ), that is, the annual average radiation energy; W i represents the annual radiation energy per square meter in the analysis area in year i (MJ / m 2 ), i∈(1,5).

[0061] S2: Based on the annual average radiation energy, calculate the average annual power generation per square meter.

[0062] Specifically, according to the usual assumptions, if 50% of the existing land available for distributed photovoltaic installations is covered with photovoltaic panels, and the conversion efficiency of converting radiation energy into electrical energy is α, the average annual power generation per square meter is W. electric As shown in the following formula, the unit is kWh:

[0063]

[0064] Where W electric It represents the average annual electricity generation per square meter in the analysis area, and α represents the conversion efficiency of photovoltaic panels in converting radiation energy into electrical energy.

[0065] S3: Based on the average annual power generation per square meter, calculate the annual power generation of distributed photovoltaics in the analysis area.

[0066] Specifically, based on the area where distributed photovoltaics can be installed in the analysis area, the annual power generation of distributed photovoltaics in the analysis area is calculated as shown in the following formula:

[0067] W annual,electric =W electric ·S PV,square ·η (3)

[0068] In the formula, S PV,square W represents the area in the analysis area where distributed photovoltaics can be installed. annual,electric It represents the annual power generation of distributed photovoltaic in the analysis area, and η represents the conversion efficiency of distributed photovoltaic DC side component power after the inverter.

[0069] S4: Based on the annual power generation of distributed photovoltaics in the analysis area, the maximum power value of distributed photovoltaics is calculated.

[0070] Specifically, based on the annual power generation and maximum utilization hours of distributed photovoltaics in the analysis area, the maximum power value of distributed photovoltaics can be calculated as shown in the following formula:

[0071]

[0072] Where P PV,N Indicates the maximum power value of distributed photovoltaic, T max Indicates the maximum utilization hours.

[0073] S5: Based on the maximum power value of distributed photovoltaics, calculate the output power of distributed photovoltaics in the midday mode.

[0074] Specifically, according to the actual installed area of ​​distributed photovoltaic in the analysis area and the simultaneous rate λ of regional distributed photovoltaic output under the noon mode, the distributed photovoltaic output power under the noon mode can be calculated as shown in the following formula:

[0075]

[0076]

[0077] Where P PV,actualrepresents the output power of distributed photovoltaic power generation in the analysis area at noon, S PV,square,actual represents the actual installed area of ​​distributed photovoltaic in the analysis area, λ i represents the maximum simultaneous rate of photovoltaic output in the noon mode in the i-th year in the analysis area in the past five years, and λ represents the average maximum simultaneous rate of photovoltaic output in the noon mode in the analysis area in the past five years.

[0078] S6: Based on the distributed photovoltaic output power in midday mode, calculate the 220 kV grid load.

[0079] Among them, the 220 kV grid load P load,network The calculation formula is as follows:

[0080] P load,network =P load,region -P source -P load,user (7)

[0081] P source =P PV,actual +P wind,actual +P conventional (8)

[0082] P wind,actual =λ wind S wind (9)

[0083]

[0084] Where P load,region represents the dispatching load in the analyzed area, P source Indicates the output power of power sources of 110 kV and below in the analysis area, P load,user P represents the load of large users in the analysis area; wind,actual P represents the output power of wind turbines with a voltage of 110 kV or less in the analyzed area; conventional Indicates the output power of conventional power sources of 110 kV and below in the analysis area. It can be taken according to historical conditions and regarded as a constant; wind Indicates the output synchronization rate of wind turbines of 110 kV and below in the analysis area; S wind represents the installed capacity of wind turbines in the region; i,wind It represents the maximum simultaneous rate of wind power output in the noon mode in the i-th year in the analysis area in the past five years.

[0085] S7: Calculate the 220 kV grid-connected substation capacity based on the 220 kV grid supply load and the 220 kV grid planning technical guidelines.

[0086] Specifically, according to the technical guidelines for 220 kV power grid planning, the regional off-grid capacity load ratio is within the normal range when it is controlled within the range of 1.7 to 1.9 (i.e. R∈(1.7,1.9)). The off-grid capacity load ratio is calculated as follows:

[0087]

[0088] Where R represents the 220 kV grid load ratio in the analysis area, S trans,220kV It indicates the existing main transformer capacity of 220 kV substation in the analysis area.

[0089] When the regional 220 kV grid-connected capacity load ratio R ≥ 1.9 calculated according to formula (11), it is necessary to exclude the main transformer capacity S of the grid-connected substation from the existing main transformer capacity of the 220 kV substation in the analysis area. trans,220kV,up The grid-connected substation can be determined by the relevant departments during the actual grid operation process, and equation (11) becomes as follows:

[0090]

[0091] Therefore, according to the 220 kV power grid planning technical guidelines R∈(1.7,1.9), the 220 kV grid substation capacity is calculated as:

[0092] 1.7P load,network ≤S require,trans,220kV ≤1.9P load,network (13)

[0093] In the formula, S require,trans,220kV It indicates the substation capacity of the analyzed area that meets the technical requirements of 220 kV power grid planning, that is, the 220 kV off-grid substation capacity.

[0094] S8: Based on the 220 kV grid-connected substation capacity, calculate the substation capacity deficit in the analysis area.

[0095] Specifically, analyze the regional transformer capacity shortage ΔS trans,220kV , as shown below:

[0096] ΔS trans,220kV =S require,trans,220kV -S trans,220kV (14)

[0097] S9: Based on the heavy load of renewable energy on-grid and off-grid at each 220 kV substation in the analysis area, calculate the load rate of the heavy-loaded 220 kV substation in the analysis area.

[0098] Specifically, according to the heavy load of renewable energy on-grid and off-grid in each 220 kV substation in the analysis area, the main transformer N-1 analysis of these substations is carried out, as shown in the following formula:

[0099]

[0100] In the formula, α j P represents the load rate of the jth heavily loaded 220 kV substation in the regional power grid, j，load，sub represents the renewable energy on-grid or off-grid load of the j-th substation, S j，k，trans It represents the capacity of the kth 220 kV main transformer in the jth 220 kV substation, and n represents the number of 220 kV main transformers in the jth substation.

[0101] S10: Based on the analysis of the load rate of the heavily loaded 220 kV substation in the regional power grid, calculate the additional substation capacity that needs to be added.

[0102] Specifically, from the perspective of equipment safety operation, considering the load transfer of the lower-level power grid and the absence of stable control to remove new energy, the load rate of the heavy-load 220 kV substation in the regional power grid should not exceed 100%. Therefore, according to formula (15), when the load rate of the heavy-load 220 kV substation in the regional power grid is greater than 100%, the substation needs to increase the substation capacity ΔS j，trans，capcity , as shown below:

[0103] ΔS j，trans，capcity =max{S j，1,trans , …, S j，n，trans} (16)

[0104] When in equation (15), According to the existing 220 kV substation main transformer capacity, for urban 220 kV substations, ΔS j，trans,capcity = 240,000 kVA; for county-level 220 kV substations, ΔS j，trans,capcity =180,000 kVA.

[0105] S11: Based on the required additional transformer capacity of the substation, calculate the actual additional 220 kV transformer capacity.

[0106] Specifically, the actual increase in 220 kV transformer capacity ΔS capacity，220kV As shown below:

[0107]

[0108] In the formula, ΔS capacity,220kV It represents the actual increase of 220 kV substation substation capacity, and m represents the number of 220 kV substations in the analysis area.

[0109] S12: Based on the analysis of the regional transformer capacity shortage and the actual increase in 220 kV transformer capacity, the regional power grid 220 kV transformer capacity demand assessment index is calculated.

[0110] Specifically, the calculation of the regional power grid 220 kV substation capacity demand assessment index δ is as follows:

[0111]

[0112] The smaller the regional power grid 220 kV substation capacity demand assessment index δ calculated according to formula (18), the more consistent the substation capacity shortage of each heavy-load substation is with the overall 220 kV substation capacity shortage in the analysis area, and it is necessary to increase the capacity of these heavy-load substations.

[0113] Example

[0114] Taking a certain regional power grid as an example, the maximum dispatching load of the regional power grid in a certain target year is 2,620 MW. Without considering the addition of new 220 kV substation capacity, the regional 220 kV substation capacity is 4,560 MVA, of which the online substation capacity is 1,800 MVA.

[0115] According to the analysis of power sources of 110 kV and below, the installed capacity of thermal power units is 51 MW, that of hydropower units is 1421 MW, that of wind power units is 3866 MW, and that of photovoltaic units is 2617 MW. According to the analysis of historical operation data, under the high-load operation mode, the output power of thermal power units is 45 MW, that of hydropower units is 355 MW, and that of wind power units is 167 MW.

[0116] In the midday mode during the flood season, the output power of thermal power units is 51 MW, the output of hydropower units is 639 MW, the output of wind power units is 1338 MW, and the output of photovoltaic units is 1162 MW. The specific results are shown in the following table:

[0117]

[0118]

[0119] According to the requirements of capacity-load ratio in the 220 kV planning and design guidelines, the required 220 kV grid-connected substation capacity under large-scale operation is 2851 MVA, and the required substation capacity range is: (2905, 3247) MVA.

[0120] Therefore, under the condition of satisfying the capacity-load ratio constraint, the required additional 220 kV grid-connected substation capacity is (54, 396) MVA.

[0121] Taking into account that the downstream substation is the main transformer N-1 and taking into account the load transferred from the lower-level power grid, the regional power grid 220 kV substation needs to increase the 220 kV substation capacity by 480 MVA.

[0122] Considering that when the grid-connected substation does not take stabilization measures and meets the N-1 verification, the grid-connected substation 220 kV substation capacity that needs to be increased is 360 MVA. Therefore, based on the above analysis, the regional grid 220 kV substation capacity demand assessment index can be calculated as shown in the following formula:

[0123]

[0124] If the added 220 kV substation capacity in the area is not taken into account, the demand assessment index of 220 kV substation capacity in the regional power grid can be calculated as shown in the following formula:

[0125]

[0126] Therefore, without considering increasing the substation capacity of renewable energy grid-connected substations, the substation capacity shortage of each grid-connected heavy-loaded substation remains consistent with the overall 220 kV substation capacity shortage in the region, and it is necessary to increase the capacity of these heavy-loaded substations.

[0127] The beneficial effects of the 220 kV substation capacity demand assessment method considering regional power grid irradiance provided in this embodiment include:

[0128] The proposed method has very important guiding significance for power grid planners. It can provide a theoretical analysis basis for planning work, power grid construction, and improving power supply capacity and reliability of power grids, and has good engineering practice significance.

[0129] It should be noted that, in the absence of conflict, the features in the embodiments of this application may be combined with each other.

[0130] The above are only preferred embodiments of the present application and are not intended to limit the present application. For those skilled in the art, the present application may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application shall be included in the protection scope of the present application.

Claims

1. A 220 kV transformer capacity demand assessment method considering regional power grid irradiance, characterized in that: The method comprises: S1: Get the annual average radiation energy of the analyzed area; S2: Based on the annual average radiation energy, calculate the average annual power generation per square meter; S3: Based on the average annual power generation per square meter, calculate the annual power generation of distributed photovoltaics in the analysis area; S4: Calculate the maximum power value of distributed photovoltaics based on the annual power generation of distributed photovoltaics in the analysis area; S5: Based on the distributed photovoltaic maximum power value, calculate the distributed photovoltaic output power in the midday mode; S6: Calculate the 220 kV grid load based on the distributed photovoltaic output power in the midday mode; S7: Calculate the 220 kV grid-connected transformer capacity according to the 220 kV grid supply load and the 220 kV grid planning technical guidelines; S8: Calculate the transformer capacity shortage in the analysis area based on the 220 kV grid-connected transformer capacity; S9: Calculate the load rate of the heavy-loaded 220 kV substation in the analysis area based on the heavy-load conditions of renewable energy on-grid and off-grid in each 220 kV substation in the analysis area; S10: Calculating the substation capacity that needs to be increased based on the load rate of the heavy-load 220 kV substation in the analysis area power grid; S11: based on the required additional substation capacity, calculating the actual additional 220 kV substation capacity; S12: Based on the analysis of the regional transformer capacity shortage and the actual increase in 220 kV transformer capacity, calculate the regional power grid 220 kV transformer capacity demand assessment index.

2. The 220 kV transformer capacity demand assessment method considering regional power grid irradiance according to claim 1 is characterized in that: In S2, the average annual electricity generation per square meter is calculated as follows: Where W electric represents the average annual power generation per square meter in the analysis area, α represents the conversion efficiency of photovoltaic panels to convert radiation energy into electrical energy, W ave It represents the average annual radiation energy per square meter in the analysis area in the past five years.

3. The 220 kV transformer capacity demand assessment method considering regional power grid irradiance according to claim 2 is characterized in that: In S3, the annual power generation of distributed photovoltaics in the analysis area is calculated as follows: W annual,electric =W electric ·S PV,square ·or In the formula, S PV,square W represents the area in the analysis area where distributed photovoltaics can be installed. annual,electric It represents the annual power generation of distributed photovoltaic in the analysis area, and η represents the conversion efficiency of distributed photovoltaic DC side component power after the inverter.

4. The 220 kV transformer capacity demand assessment method considering regional power grid irradiance according to claim 3 is characterized in that: In S4, the maximum power value of distributed photovoltaic is calculated as follows: Where P PV,N Indicates the maximum power value of distributed photovoltaic, T max Indicates the maximum utilization hours.

5. The 220 kV transformer capacity demand assessment method considering regional power grid irradiance according to claim 4 is characterized in that: In S5, the calculation method of distributed photovoltaic output power in midday mode is as follows: Where P PV,actual represents the output power of distributed photovoltaic power generation in the analysis area at noon, S PV,square,actual It represents the actual installed area of ​​distributed photovoltaic in the analysis area, and λ represents the average maximum simultaneous rate of photovoltaic output in the analysis area at noon in the past five years.

6. The 220 kV transformer capacity demand assessment method considering regional power grid irradiance according to claim 5 is characterized in that: In S6, the 220 kV grid load P load,network The calculation method is as follows: P load,network =P load,region -P source -P load,user P source =P PV,actual +P wind,actual +P conventional Where P load,region represents the dispatching load in the analyzed area, P source Indicates the output power of power sources of 110 kV and below in the analysis area, P load,user P represents the load of large users in the analysis area; wind,actual P represents the output power of wind turbines with a voltage of 110 kV or less in the analyzed area; conventional Indicates the output power of conventional power sources of 110 kV and below in the analysis area.

7. The 220 kV transformer capacity demand assessment method considering regional power grid irradiance according to claim 6 is characterized in that: In S7, the calculation method of 220 kV grid transformer capacity is as follows: <h2 style=";text-align:left;direction:ltr">1.7P<h2 style=";text-align:left;direction:ltr"> load,network <h2 style=";text-align:left;direction:ltr"> ≤S<h2 style=";text-align:left;direction:ltr"> require,trans,220kV <h2 style=";text-align:left;direction:ltr"> ≤1.9P<h2 style=";text-align:left;direction:ltr"> load,network In the formula, S require,trans,220kV It indicates the substation capacity of the analyzed area that meets the technical requirements of 220 kV power grid planning, that is, the 220 kV off-grid substation capacity.

8. The 220 kV transformer capacity demand assessment method considering regional power grid irradiance according to claim 7 is characterized in that: In S8, the regional transformer capacity shortage ΔS is analyzed trans,220kV The calculation method is as follows: ΔS trans,220kV =S require,trans,220kV -S trans,220kV In the formula, S trans,220kV It indicates the existing main transformer capacity of 220 kV substation in the analysis area.

9. The 220 kV transformer capacity demand assessment method considering regional power grid irradiance according to claim 8 is characterized in that: S10 includes: When the load rate of the heavy-load 220 kV substation in the analyzed area is greater than 100%, the substation needs to increase the substation capacity ΔS j,trans,capcity , as shown below: ΔS j,trans,capcity =max{S j,1,trans ,…,S j,n,trans } In the formula, S j,n,trans represents the capacity of the nth 220 kV main transformer in the jth 220 kV substation, and n represents the number of 220 kV main transformers in the jth substation; In S11, the actual increase in 220 kV transformer capacity ΔS capacity,220kV As shown below: In the formula, ΔS capacity,220kV It represents the actual increase of 220 kV substation substation capacity, and m represents the number of 220 kV substations in the analysis area.

10. The 220 kV transformer capacity demand assessment method considering regional power grid irradiance according to claim 9 is characterized in that: In S12, the regional power grid 220 kV substation capacity demand assessment index δ is calculated as follows:

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