A method and system for calculating the access capacity of a photovoltaic project in a distribution network substation area

Abstract

The present invention provides a method and system for calculating the access capacity of a photovoltaic project in a distribution network substation area. The method of the present invention includes selecting an optimal substation area group that meets the conditions for local photovoltaic consumption according to the cumulative transmitted power of each distribution transformer in the substation area during the effective photovoltaic power generation time on a random day; calculating a recommended installed photovoltaic capacity array based on the highest load factor array of the distribution transformer; and combining the electricity sales revenue and photovoltaic cost of the substation area, and using an approximation algorithm to calculate the recommended installed photovoltaic capacity that meets the load requirements. By selecting the substation areas suitable for installing distributed photovoltaics and calculating the recommended access capacity in combination with the actual situation of the substation areas, the present invention can more accurately determine the substation areas suitable for installing distributed photovoltaics, reduce the operating pressure of the distribution network and line losses.

Description

Technical Field

[0001] The present invention belongs to the technical field of power grid control, and particularly relates to a method and system for calculating the access capacity of a photovoltaic project in a distribution network substation area. Background Art

[0002] With the continuous development of the pilot work of county-wide photovoltaic, distributed photovoltaics are continuously connected to the low-voltage side of rural distribution network substations. The access capacity and location of photovoltaics in the substation area affect the operation level of equipment such as distribution transformers and low-voltage conductors in the substation area, and determine the consumption of photovoltaic power generation, thus having a certain impact on the economic investment of photovoltaic development projects. The existing methods for calculating the access capacity of photovoltaics to the substation area mainly estimate the access capacity of photovoltaics based on the capacity of the distribution transformer in the substation area, so that the total power of photovoltaic power generation does not exceed the total power of the distribution transformer.

[0003] However, the existing methods only consider from the perspective of photovoltaic investment developers, seeking the maximum installed capacity, and do not selectively access the photovoltaic capacity according to the actual load operation level of the distribution network substation area, resulting in ineffective local consumption of photovoltaic power generation in some substations. Although it does not cause the problem of heavy overload of the outgoing equipment during the process of sending power to the distribution transformer, it increases the losses of equipment such as the substation area and medium-voltage lines, and does not have good economy. Summary of the Invention

[0004] In view of this, the present invention aims to solve the problem that the photovoltaic access capacity estimated by the existing calculation method increases the losses of equipment such as the substation area and medium-voltage lines and does not have good economy.

[0005] To solve the above technical problems, the present invention provides the following technical solutions:

[0006] In the first aspect, the present invention provides a method for calculating the access capacity of a photovoltaic project in a distribution network substation area, including the following steps:

[0007] Collect the output power data of each distribution transformer in the substation area and calculate the cumulative transmitted power of the distribution transformer during the effective photovoltaic power generation time on a random day;

[0008] Select the substations that meet the conditions for local consumption of photovoltaics according to the cumulative transmitted power to form a preferred substation group;

[0009] Correlate the cumulative output power array of the preferred substation group during the effective photovoltaic power generation time every day within a set time range and the array of the highest load rate of the distribution transformer, and calculate the array of the recommended installed photovoltaic capacity according to the array of the highest load rate of the distribution transformer;

[0010] Combining the electricity sales revenue of the substation area and the photovoltaic cost, use the approximation algorithm for the cumulative output power array and the array of the recommended installed photovoltaic capacity to calculate the recommended installed photovoltaic capacity that meets the load requirements.

[0011] Further, select the substations that meet the conditions for on-site consumption of photovoltaic power according to the cumulative transmitted power, and form an optimized substation group, specifically including:

[0012] Determine the condition for a substation to be suitable for photovoltaic access according to the distribution transformer operation requirements as W1 / (S0*a*b)>N set , where W1 is the cumulative transmitted power, S0 is the rated capacity of the distribution transformer, a is the heavy-load operation condition of the distribution transformer, b is the full-time domain duration, and N set is a set value;

[0013] Screen according to the rated capacity of the distribution transformer of the cumulative transmitted power of each substation on a random day, and form an optimized substation group with the substations that meet the conditions.

[0014] Further, calculate the recommended installed photovoltaic capacity array according to the highest load rate group of the distribution transformer, and the specific calculation is as follows:

[0015] S pv =P max / c

[0016] In the formula, S pv is the recommended installed photovoltaic capacity, P max is the highest load rate of the distribution transformer, and c is the photovoltaic power generation efficiency.

[0017] Further, combine the substation electricity sales revenue and the photovoltaic cost, and use the approximation algorithm to calculate the recommended installed photovoltaic capacity that meets the load requirements for the cumulative output power array and the recommended installed photovoltaic capacity array, specifically including:

[0018] Record the cumulative output power array as W (W1, W2,..., W n ), and the recommended installed photovoltaic capacity array S PV ((S PV1 , S PV2 ,..., S PVn ), where n represents the set time range;

[0019] Obtain the electricity sales price C 电价 and the comprehensive daily cost C pv of photovoltaic construction, and calculate the electricity sales revenue W n *C 电价 of on-site consumption of photovoltaic power and the comprehensive cost S PVn *C pv of the recommended photovoltaic construction;

[0020] Perform iterative calculations according to W n *C 电价 -S PVn *C pv ≥ε to obtain the installed photovoltaic capacity of the substation that meets the expected revenue, where ε is the expected revenue value.

[0021] Further, after forming the preferred substation area group, it also includes screening out heavily overloaded substation areas. The specific steps of screening out heavily overloaded substation areas include:

[0022] Obtain the load rate conditions of the distribution transformers in each substation area within the photovoltaic power generation invalid time in the preferred substation area group;

[0023] Record the number of times the load rate of each substation area reaches the heavy load rate condition. If the number of times reaches the preset value, record the corresponding substation area as a heavily overloaded substation area and screen it out within the preferred substation area group.

[0024] In a second aspect, the present invention provides a measurement system for the access capacity of a photovoltaic project in a distribution network substation area, including:

[0025] A data acquisition unit, configured to collect the output power data of the distribution transformers in each substation area and calculate the cumulative transmitted power of the distribution transformers during the photovoltaic effective power generation time within a random day;

[0026] A substation area selection unit, configured to select substation areas that meet the conditions for on-site photovoltaic consumption according to the cumulative transmitted power to form a preferred substation area group;

[0027] A first calculation unit, configured to associate the cumulative output power array of the preferred substation area group during the photovoltaic effective power generation time every day within a set time range and the array of the highest load rate of the distribution transformer, and calculate the array of the recommended installed photovoltaic capacity according to the array of the highest load rate of the distribution transformer;

[0028] A second calculation unit, configured to combine the electricity sales revenue of the substation area and the photovoltaic cost, and use an approximation algorithm for the cumulative output power array and the array of the recommended installed photovoltaic capacity to calculate the recommended installed photovoltaic capacity that meets the load requirements.

[0029] Further, the specific steps for the substation area selection unit to select the preferred substation area group include:

[0030] Determine that the condition for a substation area to be suitable for photovoltaic access according to the operation requirements of the distribution transformer is W1 / (S0*a*b)>N set , where W1 is the cumulative transmitted power, S0 is the rated capacity of the distribution transformer, a is the heavy load operation condition of the distribution transformer, b is the full-time domain duration, and N set is a set value;

[0031] Screen according to the rated capacity of the distribution transformer of the cumulative transmitted power of each substation area on a random day, and form a preferred substation area group with the substation areas that meet the conditions.

[0032] Further, the first calculation unit calculates the array of the recommended installed photovoltaic capacity specifically according to the following formula:

[0033] S pv =P max / c

[0034] In the formula, Spv For the recommended installed PV capacity, P max is the maximum load rate of the distribution transformer, and c is the PV power generation efficiency.

[0035] Furthermore, the second calculation unit calculates the recommended installed PV capacity that meets the load requirements, specifically including:

[0036] Record the cumulative output power array as W (W1, W2,..., W n ), and the recommended installed PV capacity array S PV ((S PV1 , S PV2 ,..., S PVn ), where n represents the set time range;

[0037] Obtain the electricity selling price C 电价 and the comprehensive daily cost C pv of PV construction, and calculate the electricity selling income W n *C 电价 from on-site PV consumption and the comprehensive cost S PVn *C pv of the recommended PV construction;

[0038] Perform iterative calculations according to W n *C 电价 -S PVn *C pv ≥ε to obtain the installed PV capacity of the substation area that meets the expected income, where ε is the expected income value.

[0039] Furthermore, it also includes: a heavy overload substation area screening unit;

[0040] The heavy overload substation area screening unit is used to obtain the load rate conditions of each distribution transformer in the preferred substation area group during the ineffective PV power generation time; record the number of times the load rate of each substation area reaches the heavy load rate condition. If the number of times reaches the preset value, record the corresponding substation area as a heavy overload substation area and screen it out within the preferred substation area group.

[0041] In summary, the present invention provides a method and system for calculating the access capacity of a PV project in a distribution network substation area. The method of the present invention includes selecting a preferred substation area group that meets the conditions for on-site PV consumption according to the cumulative transmission power of each distribution transformer in the PV effective power generation time on a random day; calculating the recommended installed PV capacity array according to the maximum load rate array of the distribution transformer; and calculating the recommended installed PV capacity that meets the load requirements by using an approximation algorithm in combination with the electricity selling income and PV cost of the substation area. By selecting the substation areas suitable for installing distributed PV and calculating the recommended access capacity in combination with the actual situation of the substation areas, the present invention can more accurately determine the substation areas suitable for installing distributed PV, reduce the operation pressure and line loss of the distribution network. Description of the Drawings

[0042] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the accompanying drawings required for the description of the embodiments or the prior art. Obviously, the accompanying drawings in the following description are only some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other accompanying drawings can be obtained based on these drawings.

[0043] Figure 1 It is a schematic flowchart of a method for calculating the access capacity of a photovoltaic project in a distribution network substation area provided by an embodiment of the present invention. Specific embodiments

[0044] To make the objectives, features, and advantages of the present invention more obvious and understandable, the following will clearly and completely describe the technical solutions in the embodiments of the present invention with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the embodiments described below are only some embodiments of the present invention, rather than all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts belong to the scope of protection of the present invention.

[0045] With the continuous development of the whole-county photovoltaic pilot work, distributed photovoltaics are continuously connected to the low-voltage side of rural distribution network substations. The access capacity and location of photovoltaics in the substation area affect the operation levels of equipment such as distribution transformers and low-voltage conductors in this substation area, and determine the consumption situation of photovoltaic power generation, thereby having a certain impact on the economic investment of photovoltaic development projects. The existing methods for calculating the access capacity of photovoltaics connected to the substation area mainly estimate the access capacity of photovoltaics based on the capacity of the distribution transformer in the substation area, so that the total power of photovoltaic power generation does not exceed the total power of the distribution transformer.

[0046] However, the existing methods only consider from the perspective of photovoltaic investment developers, seeking the maximum installed capacity, and do not selectively connect the photovoltaic capacity according to the actual load operation level of the distribution network substation area, resulting in ineffective local consumption of photovoltaic power generation in some substations. Although it does not cause the problem of heavy overload of the outgoing equipment during the process of sending power to the distribution transformer, it increases the losses of equipment such as substations and medium-voltage lines, and does not have good economy.

[0047] Based on this, the present invention provides a system for calculating the access capacity of a photovoltaic project in a distribution network substation area.

[0048] The following will introduce in detail an embodiment of a method for calculating the access capacity of a photovoltaic project in a distribution network substation area of the present invention.

[0049] Please refer to Figure 1 , this embodiment provides a method for calculating the access capacity of a photovoltaic project in a distribution network substation area, including:

[0050] S100: Collect the output power data of distribution transformers in each substation area and calculate the cumulative transmitted power of the distribution transformer during the effective photovoltaic power generation time within a random day.

[0051] Use the intelligent distribution transformer terminal meters with full coverage to collect the real-time power data of the distribution transformer, and collect the load rate data of the distribution transformer recorded in real time by the distribution transformer terminal, and upload them to the database to realize the regular collection of the output power data of the distribution transformer in the substation area.

[0052] Among them, the effective photovoltaic power generation time during the day and the ineffective photovoltaic power generation time at night can be defined. The period from 06:00 to 18:00 is the effective photovoltaic power generation time, and the periods from 18:00 to 24:00 and from 00:00 to 06:00 of the next day are the ineffective photovoltaic power generation times.

[0053] S200: Select the substation areas that meet the conditions for local photovoltaic power consumption according to the cumulative transmitted power to form an optimal substation area group.

[0054] Through the transmitted power data W1 of the distribution transformer during the effective photovoltaic power generation time within a random day recorded and the rated capacity S0 of the distribution transformer, an optimal substation area group X1 that meets the conditions for local photovoltaic power consumption is selected through the relationship of the proportion of the cumulative transmitted power of the distribution transformer. The conditions for the substation area to be suitable for photovoltaic access are as follows:

[0055] W1 / (S0*a*b)>N set

[0056] Among them, W1 is the cumulative transmitted power, S0 is the rated capacity of the distribution transformer, a is the heavy-load operation condition of the distribution transformer, which is taken as 0.8 in this embodiment, b is the full-time domain duration, which is taken as 12 in this embodiment, and N set is a set value, which is taken as 50% in this embodiment.

[0057] That is, the substation areas with the transmitted power during the effective photovoltaic power generation time / the average full-time domain power consumption under the heavy-load operation of the distribution transformer exceeding 50% are screened out through this calculation formula.

[0058] S300: Correlate the cumulative output power array of the optimal substation area group during the effective photovoltaic power generation time every day within a set time range and the maximum load rate array of the distribution transformer, and calculate the recommended installed photovoltaic capacity array according to the maximum load rate array of the distribution transformer.

[0059] According to the optimal substation area group X1 that meets the conditions for local photovoltaic power consumption, correlate the maximum power P during the effective photovoltaic power generation time within one month max , and the following measurement formula needs to be satisfied, where S pv is the installed capacity of distributed photovoltaic recommended for this substation area;

[0060] S pv =P max / c (1)

[0061] Among them, c is the current reference photovoltaic solar power generation efficiency, that is, the power generation efficiency of the photovoltaic is 70%.

[0062] Based on the data substation area group X1, by correlating the cumulative output power array W (W1, W2, W3, …, Wn, Wn+1, …, W30) within the effective power generation time of the photovoltaic every day in a month during the peak load month; correlating the maximum load rate P of the distribution transformer within the effective power generation time of the photovoltaic every day in a month during the peak load month max Array P MAX (P MAX1 、P MAX2 、P MAX3 、…、P MAXn 、P MAXn+1 、…、P MAX30 ); through formula (1), obtain the array S of the recommended installed photovoltaic capacity PV ((S PV1 、S PV2 、S PV3 、…、S PVn 、S PVn+1 、…、S PV30 ).

[0063] S400: Combine the substation electricity sales revenue and the photovoltaic cost, and use the approximation algorithm to calculate the recommended installed photovoltaic capacity that meets the load requirements for the cumulative output power array and the array of recommended installed photovoltaic capacity.

[0064] In this step, the process of calculating using the approximation algorithm includes:

[0065] 1) Based on the cumulative output power array W (W1, W2, W3, …, W n 、W n+1 、…、W 30 ) within the effective power generation time of the photovoltaic every day in the peak load month of the data substation area group X1, by manually inputting the electricity sales price C electricity price, the electricity sales revenue W n *C 电价 can be obtained;

[0066] 2) Based on the array S of the recommended installed photovoltaic capacity PV ((S PV1 、S PV2 、S PV3 、…、S PVn 、S PVn+1 、…、S PV30 ), by manually inputting the comprehensive average daily cost C pv of the construction and operation of the unit capacity photovoltaic, the comprehensive cost S PVn *C pv of the recommended photovoltaic construction can be obtained;

[0067] 3) According to the approximation algorithm W n *C 电价 -S PVn *C pv ≥ε for iterative operation, where ε is the expected revenue value.

[0068] Through this calculation formula, it can be determined that the electricity sales revenue generated by the actual transmitted electricity on a certain day minus the daily cost generated by the corresponding recommended installed PV capacity is greater than the set expected revenue, and it is determined that the PV installation capacity at this iteration is the recommended capacity.

[0069] In addition, after forming the preferred substation area group, it also includes screening out overloaded and heavily overloaded substations. It includes recording the load rate situation of the distribution transformer in the substation area during the invalid time of PV power generation, that is, the load rate data and time (i.e., the heavy load rate condition). If the power output exceeds 80% of its capacity and lasts for more than 60 minutes, the situation is recorded as the number of heavy load times m. If the number of heavy load times m > 10 within a month, then this part of the substation area is a heavily overloaded substation area Y2. The heavy overload of the distribution transformer in this part of the substation area cannot be solved by PV access and needs to add a new distribution transformer to increase the distribution transformer capacity of the substation area to solve the heavy overload problem of the distribution transformer.

[0070] This embodiment divides the PV access work in the low-voltage substation area into two steps. First, it uses the electricity quantity data, power information, etc. recorded by the distribution transformer terminal equipment in the substation area to select the substation areas suitable for installing distributed PV. Second, for the substation areas suitable for installing distributed PV, combined with the load rate situation of the actual local consumption in the substation area and the comprehensive cost of the construction of distributed PV, the recommended installed capacity of distributed PV is calculated through the approximation algorithm.

[0071] Compared with the traditional method of estimating the installed capacity of distributed PV, this embodiment can more accurately determine which distribution transformers in the substation areas are more suitable for installing distributed PV through real-time data, improve the local consumption capacity of PV power generation, reduce the problem of energy sending up due to insufficient local consumption, and reduce the operation pressure and line loss of the distribution network. This embodiment calculates the recommended installed capacity of distributed PV through the approximation algorithm by combining the load rate situation of the actual local consumption in the substation area and the comprehensive cost of the construction of distributed PV, providing a calculation method for the installed capacity of investment in distributed PV construction.

[0072] The above is a detailed introduction to the embodiment of the calculation method for the access capacity of the PV project in the distribution network substation area of the present invention. The following will be a detailed introduction to the embodiment of the calculation system for the access capacity of the PV project in the distribution network substation area of the present invention.

[0073] This embodiment provides a calculation system for the access capacity of the PV project in the distribution network substation area, including: a data acquisition unit, a substation area selection unit, a first calculation unit, and a second calculation unit.

[0074] In this embodiment, the data acquisition unit is configured to collect the output power data of each distribution transformer in the substation area and calculate the cumulative transmitted power of the distribution transformer during the effective photovoltaic power generation time within a random day.

[0075] In this embodiment, the substation area selection unit is configured to select the substation areas that meet the conditions for local photovoltaic power consumption according to the cumulative transmitted power, and form a preferred substation area group.

[0076] It should be noted that the specific process of the substation area selection unit selecting the preferred substation area group includes:

[0077] Determine that the condition for the substation area to be suitable for photovoltaic access according to the distribution transformer operation requirements is W1 / (S0*a*b)>N set , where W1 is the cumulative transmitted power, S0 is the rated capacity of the distribution transformer, a is the heavy-load operation condition of the distribution transformer, b is the full-time domain duration, and N set is a set value;

[0078] Screen according to the rated capacity of the distribution transformer of the cumulative transmitted power of each substation area on a random day, and form a preferred substation area group with the substation areas that meet the conditions.

[0079] In this embodiment, the first calculation unit is configured to associate the cumulative output power array of the preferred substation area group during the effective photovoltaic power generation time every day within a set time range and the array of the highest load rates of the distribution transformers, and calculate the array of the recommended installed photovoltaic capacity according to the array of the highest load rates of the distribution transformers.

[0080] It should be noted that the first calculation unit calculates the array of the recommended installed photovoltaic capacity specifically according to the following formula:

[0081] S pv =P max / c

[0082] In the formula, S pv is the recommended installed photovoltaic capacity, P max is the highest load rate of the distribution transformer, and c is the photovoltaic power generation efficiency.

[0083] In this embodiment, the second calculation unit is configured to combine the electricity sales revenue of the substation area and the photovoltaic cost, and use an approximation algorithm to calculate the recommended installed photovoltaic capacity that meets the load requirements for the cumulative output power array and the array of the recommended installed photovoltaic capacity.

[0084] It should be noted that the second calculation unit calculates the recommended installed photovoltaic capacity that meets the load requirements, specifically including:

[0085] Record the cumulative output power array as W (W1, W2,..., W n ), and the array of the recommended installed photovoltaic capacity S PV ((S PV1 , S PV2 ,... SPVn ), where n represents the set time range;

[0086] Obtain the electricity selling price C 电价 and the comprehensive daily cost C of photovoltaic construction pv , calculate the electricity selling income W of on-site photovoltaic consumption n *C 电价 and the comprehensive cost S of proposed photovoltaic construction PVn *C pv ;

[0087] According to W n *C 电价 -S PVn *C pv ≥ε to perform iterative calculations to obtain the installed photovoltaic capacity of the substation area that meets the expected income, where ε is the expected income value.

[0088] Furthermore, it also includes: a heavy overload substation area screening unit;

[0089] The heavy overload substation area screening unit is used to obtain the load rate conditions of each distribution transformer in the preferred substation area group during the ineffective time of photovoltaic power generation; record the number of times the load rate of each substation area reaches the heavy load rate condition. If the number of times reaches the preset value, the corresponding substation area is recorded as a heavy overload substation area and screened out in the preferred substation area group.

[0090] It should be noted that the measurement system provided in this embodiment is used to implement the measurement method provided in the foregoing embodiment. The specific settings of each unit are based on the complete implementation of this method and will not be elaborated here.

[0091] The above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that they can still modify the technical solutions recorded in the foregoing embodiments, or perform equivalent replacements for some of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for calculating the access capacity of a photovoltaic project in a distribution network substation area, characterized in that It includes the following steps: Collect the output power data of the distribution transformers in each substation area and calculate the cumulative transmitted power of the distribution transformers during the effective photovoltaic power generation time within a random day; Select the substation areas that meet the conditions for local photovoltaic power consumption according to the cumulative transmitted power to form a preferred substation area group; Associate the cumulative output power array of the preferred substation area group during the effective photovoltaic power generation time every day within a set time range and the maximum load rate array of the distribution transformers, and calculate the recommended installed photovoltaic capacity array according to the maximum load rate array of the distribution transformers; Combining the substation area electricity sales revenue and the photovoltaic cost, use the approximation algorithm for the cumulative output power array and the recommended installed photovoltaic capacity array to calculate the recommended installed photovoltaic capacity that meets the load requirements; Select the substation areas that meet the conditions for local photovoltaic power consumption according to the cumulative transmitted power to form a preferred substation area group, specifically including: According to the operating requirements of the distribution transformer, the conditions suitable for PV access in the substation area are determined as W1 / (S0*a*b)>N set , where W1 is the cumulative transmitted power, S0 is the rated capacity of the distribution transformer, a is the heavy-load operating condition of the distribution transformer, b is the full-time domain duration, and N set is a set value; Screen according to the rated capacity of the distribution transformers of the cumulative transmitted power of each substation area on a random day, and form the preferred substation area group with the qualified substation areas; The recommended installed photovoltaic capacity array is calculated according to the maximum load rate group of the distribution transformers specifically according to the following formula: S pv = P max / c Where S pv is the recommended installed PV capacity, P max is the maximum load ratio of the distribution transformer, and c is the PV power generation efficiency; Combining the substation area electricity sales revenue and the photovoltaic cost, use the approximation algorithm for the cumulative output power array and the recommended installed photovoltaic capacity array to calculate the recommended installed photovoltaic capacity that meets the load requirements, specifically including: Denote the cumulative output power array as W i (W1, W2, …, W n ), and the recommended installed PV capacity array S PVi (S PV1 , S PV2 , … S PVn ), where n represents the set time range, i.e., the set number of days; Obtain the electricity selling price C 电价 and the comprehensive daily cost C of photovoltaic construction pv , calculate the electricity selling revenue W of on-site photovoltaic consumption i *C 电价 and the comprehensive cost S of the proposed photovoltaic construction PVi *C pv ; According to W i *C 电价 -S PVi *C pv Perform iterative calculations according to ≥ε to obtain the installed photovoltaic capacity of the transformer area that meets the expected income, where ε is the value of the expected income.

2. The measurement method for the access capacity of a photovoltaic project in a distribution network substation area according to claim 1, wherein After forming the preferred substation area group, it also includes screening out the heavily overloaded substation areas. The screening out of the heavily overloaded substation areas specifically includes: Obtain the load rate conditions of the distribution transformers in each substation area within the preferred substation area group during the ineffective photovoltaic power generation time; Record the number of times the load rate of each substation area reaches the heavy load rate condition. If the number of times reaches the preset value, record the corresponding substation area as the heavily overloaded substation area and screen it out within the preferred substation area group.

3. A measuring system for the access capacity of a photovoltaic project in a distribution network substation area, characterized in that, It includes: A data acquisition unit for collecting the output power data of the distribution transformers in each substation area and calculating the cumulative transmitted power of the distribution transformers during the effective photovoltaic power generation time within a random day; A substation area selection unit for selecting the substation areas that meet the conditions for local photovoltaic power consumption according to the cumulative transmitted power to form a preferred substation area group; A first calculation unit for associating the cumulative output power array of the preferred substation area group during the effective photovoltaic power generation time every day within a set time range and the maximum load rate array of the distribution transformers, and calculating the recommended installed photovoltaic capacity array according to the maximum load rate array of the distribution transformers; A second calculation unit for combining the substation area electricity sales revenue and the photovoltaic cost, and using the approximation algorithm for the cumulative output power array and the recommended installed photovoltaic capacity array to calculate the recommended installed photovoltaic capacity that meets the load requirements; Select the substation areas that meet the conditions for local photovoltaic power consumption according to the cumulative transmitted power to form a preferred substation area group, specifically including: According to the operating requirements of the distribution transformer, the conditions suitable for PV access in the substation area are determined to be W1 / (S0*a*b)>N set , where W1 is the cumulative transmitted power, S0 is the rated capacity of the distribution transformer, a is the heavy-load operating condition of the distribution transformer, b is the full-time domain duration, and N set is a set value; Screen according to the rated capacity of the distribution transformers of the cumulative transmitted power of each substation area on a random day, and form the preferred substation area group with the qualified substation areas; The recommended installed photovoltaic capacity array is calculated according to the maximum load rate group of the distribution transformers specifically according to the following formula: S pv = P max / c Where S pv is the recommended installed PV capacity, P max is the maximum load rate of the distribution transformer, and c is the PV power generation efficiency; Combining the substation area electricity sales revenue and the photovoltaic cost, use the approximation algorithm for the cumulative output power array and the recommended installed photovoltaic capacity array to calculate the recommended installed photovoltaic capacity that meets the load requirements, specifically including: Denote the cumulative output power array as W i (W1, W2, …, W n ), and the recommended installed PV capacity array S PVi (S PV1 , S PV2 , … S PVn ), where n represents the set time range, i.e., the set number of days; Obtain the electricity selling price C 电价 and the comprehensive daily cost C of photovoltaic construction pv , calculate the electricity selling income W of on-site photovoltaic consumption i *C 电价 and the comprehensive cost S of proposed photovoltaic construction PVi *C pv ; According to W i *C 电价 -S PVi *C pv Iterative calculations are performed with ≥ ε to obtain the installed PV capacity of the substation area that meets the expected revenue, where ε is the expected revenue value.

4. The measurement system for the access capacity of a photovoltaic project in a distribution network substation area according to claim 3, characterized in that, It also includes: a heavily overloaded substation area screening unit; The heavy overload substation area screening unit is used to obtain the load rate conditions of the distribution transformers in each substation area within the preferred substation area group during the ineffective time of photovoltaic power generation; record the number of times the load rate of each substation area reaches the heavy load rate condition, and if the number reaches the preset value, record the corresponding substation area as the heavy overload substation area and screen it out within the preferred substation area group.

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