Developable capacity evaluation method and system for distributed photovoltaic transformer area

Abstract

The invention relates to the technical field of power grid power distribution, in particular to a developable capacity evaluation method and system for a distributed photovoltaic transformer area, and the method comprises the steps: obtaining the maximum load power of a transformer area power grid according to the electric power of all users in the transformer area; according to the maximum load power of the district power grid and the total photovoltaic load power of the accessed power grid, the maximum openable capacity of the district power grid is obtained; according to the difference between the user power and the photovoltaic power in the preset historical time period of the transformer area, the transformer area photovoltaic consumption matching degree is obtained, and the transformer area power grid frequency instability is combined to obtain a transformer area power grid capacity adjustment factor; and the maximum openable capacity of the district power grid is adjusted according to the power grid capacity adjustment factor, the actual accessible photovoltaic capacity of the district power grid is obtained, photovoltaic access is operated by adopting the actual accessible photovoltaic capacity of the district power grid, and the safety and stability of the power grid and the economic operation efficiency can be improved.

Description

Technical Field

[0001] The present invention relates to the technical field of power grid distribution, and in particular to a method and system for evaluating the exploitable capacity of a distributed photovoltaic area. Background Art

[0002] With the transformation of the global energy structure and the rapid development of renewable energy, distributed photovoltaic power generation, as a clean and efficient way of energy utilization, is gradually becoming an important part of the power system. However, with the large-scale disorderly access of distributed photovoltaics, it has brought severe challenges to the access and consumption of distribution networks, and also caused a series of problems such as overvoltage in some areas and reverse overload of equipment, which hindered the healthy and orderly development of distributed photovoltaics and had a significant impact on the safety and economic operation of distribution networks.

[0003] At present, when evaluating the open capacity of distributed photovoltaic areas, the distributed photovoltaic power is generally connected based on the difference between the maximum load of the grid in this area and the installed capacity (i.e. the maximum open capacity). However, there may be a situation where the grid stability of the corresponding area is poor or the photovoltaic power generation does not match the grid load demand. Therefore, if the maximum open capacity of the grid is used as the actual photovoltaic access capacity, it may cause short-term overload and energy waste of the grid, affecting the stability of the grid. Summary of the invention

[0004] In order to solve the existing technical problem that directly using the maximum open capacity of the power grid as the actual photovoltaic access capacity will affect the stability of the power grid, the purpose of the present invention is to provide a method and system for evaluating the developable capacity of a distributed photovoltaic area. The technical solution adopted is as follows: In a first aspect of the present invention, a method for evaluating the exploitable capacity of a distributed photovoltaic area is provided, comprising: According to the power consumption of all users in the substation area, the maximum load power of the substation area power grid is obtained; According to the maximum load power of the power grid in the substation area and the total load power of the photovoltaic power grid connected to the power grid, the maximum open capacity of the power grid in the substation area is obtained; According to the difference between the power of users and photovoltaics in the preset historical time period of the substation, the photovoltaic consumption matching degree of the substation is obtained, and combined with the instability of the substation grid frequency, the substation grid capacity adjustment factor is obtained; The maximum open capacity of the substation grid is adjusted according to the grid capacity adjustment factor to obtain the photovoltaic capacity that can actually be connected to the substation grid.

[0005] In an exemplary embodiment, the maximum load power of the power grid in the substation area is obtained according to the power consumption of all users in the substation area, including: According to the total daily power consumption of users in the preset historical time period of the substation area, the maximum total daily power consumption of users is obtained; Obtain the total power consumption of the user at each sampling time within the target date corresponding to the maximum total power consumption of the user per day; According to the difference between the total power consumption of users at each sampling moment and the total power consumption of users at other sampling moments within the target date, the relative load power of the power grid at each sampling moment is obtained; The total power consumption of users at the sampling moment corresponding to the maximum relative load power of the power grid is taken as the maximum load power of the power grid in the substation area.

[0006] In an exemplary embodiment, according to the maximum load power of the grid in the substation area and the total load power of the photovoltaic power grid connected to the grid, the maximum open capacity of the grid in the substation area is obtained, including: The difference between the maximum load power of the power grid in the substation area and the total load power of the photovoltaic power grid connected to the power grid is taken as the maximum open capacity of the power grid in the substation area.

[0007] In an exemplary embodiment, the photovoltaic consumption matching degree of the substation is obtained according to the difference between the power of users and photovoltaics in a preset historical time period of the substation, including: Obtain a user total power sequence and a photovoltaic total power sequence, wherein the user total power sequence includes the user total power at each sampling moment within a preset historical time period of the area, and the photovoltaic total power sequence includes the photovoltaic total power at each sampling moment within a preset historical time period of the area; Obtaining the power difference at each sampling moment in the user's total power consumption sequence and the photovoltaic total power generation sequence, and obtaining the similarity between the user's total power consumption sequence and the photovoltaic total power generation sequence; The photovoltaic consumption matching degree of the metropolitan area is obtained according to the power difference and the similarity. The photovoltaic consumption matching degree of the metropolitan area is inversely proportional to the power difference and directly proportional to the similarity.

[0008] In an exemplary embodiment, the power difference is the absolute value of the power difference; the calculation formula of the photovoltaic consumption matching degree of the station area is: ; in, is the photovoltaic consumption matching degree of the station area, is the total power sequence of the user, is the total photovoltaic power generation sequence, For the The total power consumption of users at the sampling time, For the The total photovoltaic power generation at the sampling moment, is the similarity between the total power sequence of users and the total photovoltaic power generation sequence, is a linear normalization function, M is the number of sampling moments in the preset historical time period, For Negative correlation normalization.

[0009] In an exemplary embodiment, the process of obtaining the frequency instability of the power grid in the substation area includes: Obtaining the actual frequency of the user-side power grid at each sampling time within the target date; The frequency instability of the power grid in the substation area is obtained according to the difference between the actual frequency of the user-side power grid and the rated frequency of the power grid in the substation area at each sampling moment within the target date.

[0010] In an exemplary embodiment, the process of obtaining the area power grid capacity adjustment factor includes: Normalizing the photovoltaic consumption matching degree of the substation area and the frequency instability of the power grid in the substation area respectively; The product of the normalized photovoltaic consumption matching degree of the substation and the normalized frequency instability of the power grid in the substation is calculated to obtain the power grid capacity adjustment factor of the substation.

[0011] In an exemplary embodiment, the maximum open capacity of the power grid in the substation area is adjusted according to the power grid capacity adjustment factor to obtain the photovoltaic capacity that can actually be connected to the power grid in the substation area, including: The calculation formula for the photovoltaic capacity that can actually be connected to the grid in the substation area is as follows: ; in, The actual photovoltaic capacity that can be connected to the power grid in the area. The maximum open capacity of the power grid in the area. is the grid capacity adjustment factor.

[0012] In an exemplary embodiment, before obtaining the maximum load power of the power grid in the area according to the power consumption of all users in the area, the method for evaluating the exploitable capacity of the distributed photovoltaic area further includes: Obtain the total photovoltaic power generation and total power consumption in the preset historical time period of the substation; Obtaining the maximum photovoltaic power generation in a single day within the preset historical time period, and obtaining the actual average photovoltaic power generation voltage on the date corresponding to the maximum photovoltaic power generation in a single day; If the total photovoltaic power generation is less than the total power consumption, and the actual average photovoltaic power generation voltage is within the preset photovoltaic power generation stable voltage range, the substation executes the step of obtaining the maximum load power of the substation power grid based on the power consumption of all users in the substation.

[0013] In a second aspect of the present invention, a system for evaluating the exploitable capacity of a distributed photovoltaic area is provided, comprising: a memory and a processor; the memory is connected to the processor; the memory is used to store program instructions; the processor is used to implement the above-mentioned method for evaluating the exploitable capacity of a distributed photovoltaic area when the program instructions are executed.

[0014] The present invention has the following beneficial effects: the present invention optimizes the problem that when the maximum open capacity of the substation power grid is simply used as the actual open capacity, the stability of the power grid and the matching degree of photovoltaic power generation with the load demand of the power grid are not taken into consideration, thus affecting the stability of the power grid. First, the maximum load power of the substation power grid is obtained according to the power consumption of all users in the substation area, and then the maximum open capacity of the substation power grid is obtained by combining the maximum load power of the substation power grid and the total load power of photovoltaic power connected to the power grid; more importantly, according to the difference between the power of users and photovoltaic power in a preset historical time period of the substation, the photovoltaic absorption matching degree of the substation is obtained, and combined with the frequency instability of the substation power grid, the capacity adjustment factor of the substation power grid is obtained, so as to adjust the maximum open capacity of the substation power grid according to the power grid capacity adjustment factor, and obtain the actual accessible photovoltaic capacity of the substation power grid corresponding to the actual situation of the substation power grid, and use the actual accessible photovoltaic capacity of the substation power grid to operate photovoltaic access, which can improve the safety and stability of the power grid, as well as the economic operation efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 is a schematic diagram of photovoltaic access to a power grid provided by an embodiment of the present invention; Figure 2 It is a flow chart of a method for evaluating the developable capacity of a distributed photovoltaic area provided by an embodiment of the present invention; Figure 3 A method for evaluating developable capacity of a distributed photovoltaic area provided by an embodiment of the present invention also includes a flowchart of steps; Figure 4 is a flowchart of step 1 provided by an embodiment of the present invention; Figure 5 It is a flow chart for obtaining the photovoltaic consumption matching degree of a substation provided by an embodiment of the present invention; Figure 6 It is a flow chart for obtaining the frequency instability of the power grid in the substation area provided by an embodiment of the present invention; Figure 7 It is a flow chart for obtaining the capacity adjustment factor of the power grid in an area provided by an embodiment of the present invention. DETAILED DESCRIPTION

[0016] In order to further explain the technical means and effects adopted by the present invention to achieve the predetermined invention purpose, the specific implementation methods, structures, features and effects of the present invention are described in detail below in conjunction with the accompanying drawings and preferred embodiments. In the following description, different "one embodiment" or "another embodiment" does not necessarily refer to the same embodiment. In addition, specific features, structures or characteristics in one or more embodiments may be combined in any suitable form.

[0017] Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs.

[0018] The purpose of the method and system for evaluating the developable capacity of a distributed photovoltaic substation provided in this embodiment is to optimize the problem of grid operation risk caused by not taking the stability of the grid and the matching degree of photovoltaic power generation with the grid load demand into consideration when the maximum openable capacity of the substation is used as the actual open capacity. By analyzing the grid instability of the substation suitable for photovoltaic access and the photovoltaic consumption matching degree, the capacity adjustment factor is calculated to adjust the maximum photovoltaic expandable capacity of the substation, thereby improving the practicality and accuracy of the evaluation results.

[0019] The open capacity of distributed photovoltaic stations refers to the maximum power capacity that a distributed photovoltaic system can access and operate normally in a specific power network. Connecting distributed photovoltaics to the power grid helps to enhance the flexibility and security of power supply. Figure 1 As shown, it is for reference only. Generally, direct current is generated by photovoltaic modules, and the inverter converts direct current into alternating current. Then, the output current of multiple photovoltaic modules is aggregated through the distribution box or the junction box, and then connected to the grid through the grid-connected cabinet, while providing various protection, control, monitoring and switching functions required for grid connection. Since a large number of disorderly accesses to photovoltaic power generation corresponding to different users (i.e., terminal nodes) will affect the operating load of the grid, it is necessary to evaluate the capacity of photovoltaic power that can be connected to the grid. In order to more accurately evaluate the expandable capacity of the grid in the substation, it is necessary to obtain the real-time relevant operation data (power consumption, power, frequency, etc.) of the historical grid in the substation and the power generation data (power generation, power, etc.) of the connected photovoltaic power generation, as well as the real-time power consumption and power data of users, etc. through relevant monitoring equipment. In this way, the exploitable capacity of photovoltaic power in the substation can be accurately evaluated to ensure the safe and stable operation of the grid and distributed photovoltaic power generation.

[0020] This embodiment provides a method for evaluating the exploitable capacity of a distributed photovoltaic area. Figure 2 As shown, the following steps are included: Step 1: According to the power consumption of all users in the substation area, the maximum load power of the substation area power grid is obtained.

[0021] In an exemplary embodiment, since each distribution substation has its maximum carrying capacity, if the existing load in the substation is close to its capacity, then continuing to connect more distributed photovoltaics may lead to various dangerous problems. Therefore, before obtaining the maximum load power of the substation grid based on the power consumption of all users in the substation, it is necessary to evaluate the grid operation status of the substation to determine whether more photovoltaic power generation systems should be connected.

[0022] The total return power of the substation refers to the excess power returned to the grid through the power grid after the photovoltaic system generates electricity. The size of the total return power can more intuitively and accurately measure the degree to which the grid in this substation can accommodate the access of distributed photovoltaics. If the total return power is larger, it means that the power demand of this substation exceeds the photovoltaic power generation, and it is not recommended to continue to connect to the photovoltaic system. Otherwise, it can continue to connect.

[0023] At the same time, after photovoltaics are connected to low-voltage areas, the voltage of the area will be increased to a certain extent. In particular, when the photovoltaic power generation is too large and exceeds the standard of the area itself, it may cause the voltage of users or photovoltaics itself to exceed the limit, which will have an adverse impact on the reliability and stability of the power supply of the distribution network. Therefore, it is possible to evaluate whether this area can continue to connect to distributed photovoltaics based on whether the voltage exceeds the limit on the maximum photovoltaic power generation day.

[0024] It should be understood that the data related to photovoltaic power generation, photovoltaic voltage, photovoltaic power generation, etc. in this embodiment are all data of the photovoltaic system that has been connected to the power grid in the substation area. Based on the data of the photovoltaic system that has been connected to the power grid in the substation area, combined with other relevant data in the substation area, such as the power consumption of users in the substation area, the frequency of the power grid, etc., a comprehensive analysis is performed to finally obtain the photovoltaic capacity that can be actually connected to the substation area power grid.

[0025] In an exemplary embodiment, Figure 3 As shown, the method for evaluating the exploitable capacity of the distributed photovoltaic area also includes the following process: Step A: Obtain the total photovoltaic power generation and total power consumption in the preset historical time period of the substation.

[0026] A preset historical time period is preset, and the length of the preset historical time period and the time interval with the current moment are set according to actual needs. For example, the preset historical time period is within one month before the current moment, that is, the preset historical time period is the most recent month.

[0027] Obtain the total photovoltaic power generation within the preset historical time period of the substation, as well as the self-consumed electricity within the preset historical time period of the substation, that is, the total electricity consumption. Among them, the total photovoltaic power generation is obtained by obtaining the daily photovoltaic power generation of the connected photovoltaics every day within the preset historical time period of the substation, and then calculating the sum of the daily photovoltaic power generation within the preset historical time period of the substation to obtain the total photovoltaic power generation. Similarly, the total electricity consumption within the preset historical time period of the substation is obtained by obtaining the daily electricity consumption of the substation every day within the preset historical time period of the substation, and then calculating the sum of the daily electricity consumption of the substation within the preset historical time period of the substation to obtain the total electricity consumption.

[0028] Step B: Obtain the maximum photovoltaic power generation in a single day within a preset historical time period, and obtain the actual average photovoltaic power generation voltage on the date corresponding to the maximum photovoltaic power generation in a single day.

[0029] Since the preset historical time period includes multiple days, the photovoltaic daily power generation of each day in the preset historical time period is obtained. The maximum value is obtained from these photovoltaic daily power generation, and the maximum value is the photovoltaic daily maximum power generation. Set the date corresponding to the photovoltaic daily maximum power generation to the required date.

[0030] The required date includes multiple sampling moments, and it should be understood that the time interval between adjacent sampling moments is set according to actual needs.

[0031] The actual photovoltaic power generation voltage at each sampling time within the required date is obtained, and then the average value of the actual photovoltaic power generation voltage within the required date is calculated to obtain the actual average photovoltaic power generation voltage. The actual photovoltaic power generation voltage at any sampling time can be obtained by obtaining the actual voltage of each photovoltaic module in the area at the sampling time, calculating the average value of the actual voltage of all photovoltaic modules in the area at the sampling time, and taking it as the actual photovoltaic power generation voltage at the sampling time.

[0032] Step C: If the total photovoltaic power generation is less than the total power consumption, and the actual average photovoltaic power generation voltage is within the preset photovoltaic power generation stable voltage range, the substation executes step 1.

[0033] A photovoltaic power generation stable voltage interval is preset, and the upper limit and lower limit of the photovoltaic power generation stable voltage interval are set according to actual judgment needs.

[0034] If the total photovoltaic power generation is less than the total power consumption, it means that there is no return power, and this area can continue to connect to distributed photovoltaics; if the total photovoltaic power generation is greater than or equal to the total power consumption, it means that there is return power, and this area should not continue to connect to distributed photovoltaics. The actual average voltage of photovoltaic power generation is within the preset photovoltaic power generation stable voltage range, indicating that the photovoltaic power generation voltage is relatively stable and there is no voltage limit.

[0035] Therefore, if the total photovoltaic power generation is less than the total power consumption, and the actual average voltage of photovoltaic power generation is within the preset photovoltaic power generation stable voltage range, the substation can continue to be connected to distributed photovoltaics. If the substation is a substation that can continue to be connected to distributed photovoltaics, then the substation can continue to execute step 1.

[0036] In an exemplary embodiment, the total amount of returned electricity in a preset historical time period is obtained using the following calculation formula: ; in, The total amount of electricity returned during the preset historical time period of the substation. The total photovoltaic power generation in the preset historical time period for the substation area, Set the total electricity consumption for the historical time period for the substation.

[0037] Therefore, if It indicates that the total power generation is greater than or equal to the total power consumption, and there is a total return power. In this case, this area should not continue to connect to distributed photovoltaics. You should continue to access.

[0038] The voltage over-limit situation of the area at the maximum photovoltaic power generation in a single day is calculated in the following way. In this embodiment, the voltage over-limit judgment standard is 20% exceeding the rated voltage: ; in, The voltage limit of the area when the photovoltaic power generation exceeds the limit in a single day. The actual average voltage of photovoltaic power generation on the corresponding date of the maximum photovoltaic power generation in the substation, is the rated voltage of photovoltaic power generation, Indicates the upper voltage limit, Indicates the lower limit voltage.

[0039] Therefore, if the average voltage of this area on the date corresponding to the maximum photovoltaic power generation on a single day is within the specified range, the corresponding , you can continue to connect to distributed photovoltaics; if the average voltage is not within the specified range, then , you should not continue to access.

[0040] Then, when judging whether this area is suitable for continued access to distributed photovoltaics, if the total returned power And the voltage of the area exceeds the limit when the photovoltaic power generation exceeds the limit in a single day If all the conditions are met at the same time, the substation continues to connect to distributed photovoltaic power generation, that is, continue to execute step 1.

[0041] In addition, the criteria for the substation can be obtained according to the above process to achieve different substation screening. Specifically, if there are multiple substations to choose from, the initial selection is: And the voltage of the area exceeds the limit when the photovoltaic power generation exceeds the limit in a single day The table area is not described in detail in this embodiment.

[0042] It should be understood that if it has been determined in advance that the substation can be connected to the power grid, the above steps AC may not be performed.

[0043] If the substation is suitable for continued access to distributed photovoltaics, it means that there is idle load in the power grid of the substation, then this idle load corresponds to the maximum open capacity of the power grid. However, since the maximum open capacity of the power grid usually represents the ideal capacity without considering real-time power load fluctuations, equipment limitations and actual operating conditions, it does not mean that the actual access capacity of photovoltaics is the maximum open capacity. Therefore, it is necessary to adaptively adjust the maximum open capacity based on the instability of the power grid and the matching degree of photovoltaic absorption to determine the actual capacity of photovoltaics that can be connected. In order to achieve the above process, the maximum load power of the substation power grid is first obtained according to the power consumption of all users in the substation. Generally, the maximum open capacity is obtained by comparing the difference between the maximum load power of the substation and the output power of the connected photovoltaics, and the maximum load power of the substation power grid is generally related to the total power consumption of the users. Therefore, the maximum load power of the substation power grid can be determined with the help of the total power consumption of all users in the substation. In an exemplary embodiment, Figure 4 As shown, step 1 specifically includes: Step 1-1: According to the daily total power consumption of users in the preset historical time period of the substation, the maximum daily total power consumption of users is obtained.

[0044] Get the total daily electricity consumption of users in the preset historical time period of the area. The total daily electricity consumption of users is the sum of the electricity consumption of all users on each day in the preset historical time period of the area.

[0045] Compare the total daily electricity consumption of users in each day of the preset historical time period in the substation area, and get the maximum value, which is the maximum total daily electricity consumption of the user.

[0046] Step 1-2: Obtain the total power consumption of the user at each sampling time within the target date corresponding to the user's maximum total power consumption per day.

[0047] The date corresponding to the user's maximum daily total electricity consumption is obtained according to the user's maximum daily total electricity consumption, that is, the day within the preset historical time period corresponding to the user's maximum daily total electricity consumption, and the date corresponding to the user's maximum daily total electricity consumption is defined as the target date.

[0048] The total power consumption of users at each sampling time within the target date is obtained. Specifically, the power consumption of each user at each sampling time within the target date is obtained. For any sampling time, the power consumption of all users at the sampling time is added up to obtain the total power consumption at the sampling time, that is, the total power consumption of users at the sampling time, thereby obtaining the total power consumption of users at each sampling time within the target date. The calculation formula is as follows: ; in, The first The total power consumption of users at the sampling time is is the kth user’s The power consumption at each sampling moment, is the number of users in the area.

[0049] Step 1-3: According to the difference between the total power consumption of users at each sampling moment and the total power consumption of users at other sampling moments within the target date, the relative load power of the power grid at each sampling moment is obtained.

[0050] For any sampling time, obtain the difference between the total power consumption of users at this sampling time within the target date and the total power consumption of users at other sampling times within the target date. This difference is the relative load power of the power grid, which represents the power difference between this sampling time and other sampling times. The calculation formula is as follows: ; in, For the The relative load power of the power grid at the sampling moment, For the The total power consumption of users at the sampling time is is the number of sampling moments within the target date, m-1 represents the number of sampling moments within the target date except the The number of sampling moments other than the sampling moments.

[0051] By adopting the above method, the difference between the total power consumption of users at each sampling moment and the total power consumption of users at other sampling moments within the target date is obtained, that is, the relative load power of the power grid at each sampling moment is obtained.

[0052] The larger the The degree to which the total power consumption of users at a sampling moment is greater than that at other sampling moments.

[0053] Step 1-4: The total power consumption of users at the sampling moment corresponding to the maximum relative load power of the power grid is taken as the maximum load power of the power grid in the substation area.

[0054] After obtaining the relative load power of the power grid at each sampling moment, the maximum relative load power of the power grid is obtained, and the total power consumption of users at the sampling moment corresponding to the maximum relative load power of the power grid is taken as the maximum load power of the power grid in the substation area.

[0055] Step 2: According to the maximum load power of the power grid in the substation area and the total load power of the photovoltaic power connected to the grid, the maximum open capacity of the power grid in the substation area is obtained.

[0056] The maximum open capacity of the power grid in the substation area can be calculated by subtracting the total load power of the photovoltaic power grid connected to the grid in the substation area from the maximum load power of the power grid in the substation area. Then, the difference between the maximum load power of the power grid in the substation area and the total load power of the photovoltaic power grid connected to the grid is taken as the maximum open capacity of the power grid in the substation area. The calculation formula is as follows: ; in, The maximum open capacity of the power grid in the area. is the maximum load power of the power grid in the substation area, is the total photovoltaic load power connected to the grid in the substation. The total photovoltaic load power connected to the grid can be obtained by first obtaining the load power of each photovoltaic module connected to the grid in the substation, and then calculating the sum of the load power of all photovoltaic modules connected to the grid in the substation to obtain the total photovoltaic load power connected to the grid in the substation.

[0057] Step 3: According to the difference between the power of users and photovoltaics in the preset historical time period of the substation, the photovoltaic consumption matching degree of the substation is obtained, and combined with the instability of the substation grid frequency, the substation grid capacity adjustment factor is obtained.

[0058] Step 2 obtains the maximum open capacity of the substation grid. Then, based on the frequency instability of the substation grid and the matching degree of photovoltaic power consumption in the substation, the maximum open capacity of the substation grid is adaptively adjusted to determine the actual capacity of photovoltaic power that can be connected, so as to connect as many distributed photovoltaic power generation systems as possible while ensuring the stable operation of the power grid.

[0059] According to the difference between the power of users and photovoltaic power in the preset historical time period of the substation, the substation photovoltaic consumption matching degree is obtained. The substation photovoltaic consumption matching degree can measure the matching degree between photovoltaic power generation and grid load demand in a power system. The greater the substation photovoltaic consumption matching degree, the closer the substation power load is to the photovoltaic power generation load, which means that the supply and demand of the substation is more balanced, and there is no need to connect to other distributed photovoltaics; the smaller the substation photovoltaic consumption matching degree, the less the photovoltaic power generation load meets the power load, and more distributed photovoltaics can be connected.

[0060] In an exemplary embodiment, Figure 5As shown in the figure, the process of obtaining the matching degree of photovoltaic consumption in the substation area includes: Step 3-1: Obtain the user's total power consumption sequence and the photovoltaic total power generation sequence.

[0061] Since the preset historical time period includes multiple sampling moments, the total power consumption of users at each sampling moment in the preset historical time period of the substation is obtained (calculated using the total power consumption of users method mentioned above). The total power consumption of users at each sampling moment in the preset historical time period of the substation constitutes a total power consumption sequence of users. Then, the total power consumption sequence of users includes the total power consumption of users at each sampling moment in the preset historical time period of the substation.

[0062] The total photovoltaic power generation power of the connected power grid in the substation area at each sampling moment in the preset historical time period of the substation area is obtained, and the total photovoltaic power generation power sequence is formed by the total photovoltaic power generation power at each sampling moment in the preset historical time period of the substation area. Then, the total photovoltaic power generation power sequence includes the total photovoltaic power generation power at each sampling moment in the preset historical time period of the substation area.

[0063] It should be understood that if the photovoltaic system connected to the substation power grid includes multiple photovoltaic modules, then the photovoltaic power generation power of each photovoltaic module in the substation at each sampling moment in a preset historical time period is obtained, and then the sum of the photovoltaic power generation power of all photovoltaic modules in the substation at each sampling moment in the preset historical time period is calculated to obtain the total photovoltaic power generation power of all photovoltaic modules in the substation at each sampling moment in the preset historical time period.

[0064] It should be noted that, since the photovoltaic components can only perform effective photovoltaic power generation during the daytime, the sampling moments in the above-mentioned preset historical time period are set as the sampling moments in each daytime in the preset historical time period.

[0065] set up is the total power sequence of the user, , For the The total power consumption of users at the sampling time is is the total photovoltaic power generation sequence, , For the The total photovoltaic power generation at the sampling moment.

[0066] Step 3-2: Obtain the power difference at each sampling moment in the user's total power consumption sequence and the photovoltaic total power generation sequence, and obtain the similarity between the user's total power consumption sequence and the photovoltaic total power generation sequence.

[0067] In an exemplary embodiment, the power difference at each sampling moment in the user's total power consumption sequence and the photovoltaic total power generation sequence can be the absolute value of the power difference. The similarity between the user's total power consumption sequence and the photovoltaic total power generation sequence can be obtained using an existing similarity calculation method, such as cosine similarity, Pearson correlation coefficient, etc. In other exemplary embodiments, the DTW distance between the user's total power consumption sequence and the photovoltaic total power generation sequence can also be calculated, and then negative correlation processing is performed to obtain similarity.

[0068] Step 3-3: Based on the power difference and similarity, obtain the photovoltaic consumption matching degree of the substation area.

[0069] The smaller the similarity between the user's total electricity consumption power sequence and the photovoltaic total power generation sequence, the greater the matching degree between the user's total electricity consumption power sequence and the photovoltaic total power generation sequence, that is, the greater the matching degree of photovoltaic consumption in the substation, the less need there is to connect to additional distributed photovoltaics.

[0070] The greater the power difference between the user's total power consumption sequence and the photovoltaic total power generation sequence at each sampling moment, the smaller the matching degree between the user's total power consumption sequence and the photovoltaic total power generation sequence, that is, the smaller the photovoltaic consumption matching degree of the substation area, the more it needs to connect to other distributed photovoltaics. Therefore, the photovoltaic consumption matching degree of the substation area is inversely proportional to the power difference and proportional to the similarity.

[0071] In an exemplary embodiment, the calculation formula of the photovoltaic consumption matching degree of the station area is: ; in, is the photovoltaic consumption matching degree of the station area, is the similarity between the total power sequence of users and the total photovoltaic power generation sequence, is a linear normalization function. M is the number of sampling moments in the preset historical time period.

[0072] Indicates The total power consumption of users at the sampling moment is The difference in total photovoltaic power generation at each sampling moment; It represents the sum of the power differences at each sampling moment in the user's total electricity consumption power sequence and the photovoltaic total power generation power sequence, that is, the overall situation of the power differences at each sampling moment in the user's total electricity consumption power sequence and the photovoltaic total power generation power sequence.

[0073] For Negative correlation normalization.

[0074] The normalization in this embodiment may adopt a linear normalization method or the following normalization method: , where z is the input data, is an exponential function with the natural constant e as the base. The negative correlation normalization method can be: .

[0075] For the regional power grid, the frequency stability of the power grid refers to whether the power grid can maintain or recover to the normal frequency range and remain stable in the long term after being disturbed (such as load changes or generator failures). Therefore, the frequency stability of the power grid directly reflects the overall stability of the power grid. The higher the stability of the power grid, the more distributed photovoltaics can be connected. Conversely, the number of connected photovoltaics should be appropriately reduced. Correspondingly, the frequency instability of the regional power grid indicates the fluctuation of the power grid. The higher the frequency instability of the regional power grid, the more distributed photovoltaics cannot be connected.

[0076] In an exemplary embodiment, the process of obtaining the frequency instability of the power grid in the substation area is as follows: Figure 6 As shown, including: Step 3-4: Obtain the actual frequency of the user-side power grid at each sampling time within the target date.

[0077] The actual frequency of the user-side power grid at each sampling time within the target date obtained in step 1 is obtained, that is, the actual frequency of the user-side power grid of each user in the substation at each sampling time. It should be understood that a power grid frequency detection device is provided at each user in the substation to detect the actual frequency of the user-side power grid of each user.

[0078] Step 3-5: According to the difference between the actual frequency of the user-side power grid and the rated frequency of the power grid in the substation area at each sampling time within the target date, the frequency instability of the power grid in the substation area is obtained.

[0079] Set the rated frequency of the power grid in the substation area. The rated frequency of the power grid in the substation area is a fixed known value, usually 50Hz.

[0080] The difference between the actual frequency of the user-side power grid and the rated frequency of the power grid in the substation area at each sampling time within the target date is obtained. The larger the difference, the more unstable the power grid frequency in the substation area, that is, the higher the instability of the power grid frequency in the substation area. In an exemplary embodiment, the calculation formula of the instability of the power grid frequency in the substation area is as follows: ; in, The frequency instability of the power grid in the substation area is is the kth user in the target date The actual frequency of the user-side power grid at the sampling moment is It is the rated frequency of the power grid in the substation area.

[0081] is the kth user in the target date The difference between the actual frequency of the user-side power grid and the rated frequency of the power grid in the substation at a sampling moment.

[0082] Comprehensive real-time frequency deviation of all users The larger its value is, the higher the instability of the grid frequency in the substation area is, and the more unstable the grid frequency is.

[0083] For the regional power grid, it is hoped that more distributed photovoltaics will be connected to the power grid with higher frequency stability, that is, the corresponding The smaller the value, the larger the actual accessible photovoltaic capacity is, and the closer it is to the maximum open capacity. At the same time, combined with the photovoltaic consumption matching degree of the substation, the smaller the photovoltaic consumption matching degree of the substation, the less the photovoltaic power generation load meets the power load, and more distributed photovoltaic access is needed.

[0084] In an exemplary embodiment, Figure 7 As shown in FIG. 1 , the process of obtaining the capacity adjustment factor of the power grid in the substation area includes: Step 3-6: Normalize the photovoltaic consumption matching degree and the grid frequency instability in the substation area respectively.

[0085] Step 3-7: Calculate the product of the normalized photovoltaic consumption matching degree of the substation and the normalized grid frequency instability of the substation to obtain the grid capacity adjustment factor of the substation. The calculation formula is as follows: ; in, is the grid capacity adjustment factor in the substation area.

[0086] Step 4: Adjust the maximum open capacity of the substation grid according to the grid capacity adjustment factor to obtain the actual photovoltaic capacity that can be connected to the substation grid.

[0087] It can be seen from the logic of the grid capacity adjustment factor in step 3 that the larger the grid capacity adjustment factor, the more it is necessary to lower the maximum open capacity of the grid in the substation. Therefore, in an exemplary embodiment, the calculation formula for the photovoltaic capacity that can actually be connected to the grid in the substation is as follows: ; in, The actual photovoltaic capacity that can be connected to the power grid in the area. The maximum open capacity of the power grid in the area. is the grid capacity adjustment factor.

[0088] The smaller the grid capacity adjustment factor The larger the photovoltaic capacity that can actually be connected to the power grid in the substation area, the smaller the photovoltaic capacity, thereby improving the accuracy of the actual accessible capacity of the power grid in the substation area.

[0089] Then, the corresponding access photovoltaic capacity can be obtained based on the actual photovoltaic capacity that can be accessed by the grid in the substation. Moreover, the optimal photovoltaic access method suitable for the substation can be selected to provide scientific distributed photovoltaic open capacity assessment guidance for low-voltage substations, support distributed photovoltaic grid-connected planning, and ensure the safe and stable operation of distributed photovoltaic substations.

[0090] This embodiment also provides a system for evaluating the exploitable capacity of a distributed photovoltaic area, including: a memory and a processor; the memory is connected to the processor, and the memory is used to store program instructions; the processor is used to implement the steps in the above-mentioned distributed photovoltaic area exploitable capacity evaluation method embodiment when the program instructions are executed.

[0091] In an exemplary embodiment, the present invention provides a computer-readable storage medium storing a computer program, which, when executed by a processor, implements the steps in the above-mentioned distributed photovoltaic area exploitable capacity assessment method embodiment.

[0092] It should be noted that the sequence of the above embodiments of the present invention is for description only and does not represent the advantages and disadvantages of the embodiments. The processes depicted in the accompanying drawings do not necessarily require the specific order or continuous order shown to achieve the desired results. In some embodiments, multitasking and parallel processing are also possible or may be advantageous.

[0093] The various embodiments in this specification are described in a progressive manner, and the same or similar parts between the various embodiments can be referenced to each other, and each embodiment focuses on the differences from other embodiments.

Claims

1. A method for evaluating the exploitable capacity of a distributed photovoltaic area, characterized in that: include: According to the power consumption of all users in the substation area, the maximum load power of the substation area power grid is obtained; According to the maximum load power of the power grid in the substation area and the total load power of the photovoltaic power grid that has been connected to the power grid, the maximum open capacity of the power grid in the substation area is obtained; According to the difference between the power of users and photovoltaics in the preset historical time period of the substation, the photovoltaic consumption matching degree of the substation is obtained, and combined with the instability of the substation grid frequency, the substation grid capacity adjustment factor is obtained; The maximum open capacity of the substation grid is adjusted according to the grid capacity adjustment factor to obtain the photovoltaic capacity that can actually be connected to the substation grid.

2. A method for evaluating the exploitable capacity of a distributed photovoltaic area as claimed in claim 1, characterized in that: According to the power consumption of all users in the substation area, the maximum load power of the substation area power grid is obtained, including: According to the total daily power consumption of users in the preset historical time period of the substation area, the maximum total daily power consumption of users is obtained; Obtain the total power consumption of the user at each sampling time within the target date corresponding to the maximum total power consumption of the user per day; According to the difference between the total power consumption of users at each sampling moment and the total power consumption of users at other sampling moments within the target date, the relative load power of the power grid at each sampling moment is obtained; The total power consumption of users at the sampling moment corresponding to the maximum relative load power of the power grid is taken as the maximum load power of the power grid in the substation area; No. The calculation formula of the relative load power of the power grid at a sampling moment is as follows: ； in, For the The relative load power of the power grid at the sampling moment, For the The total power consumption of users at the sampling time, is the number of sampling moments within the target date, m-1 represents the number of sampling moments within the target date except the The number of sampling moments other than the sampling moments, The first The total power consumption of users at the sampling time, , is the kth user’s The power consumption at each sampling moment, is the number of users in the area.

3. A method for evaluating the exploitable capacity of a distributed photovoltaic area according to claim 1, characterized in that: According to the maximum load power of the power grid in the substation area and the total load power of the photovoltaic power grid connected to the power grid, the maximum open capacity of the power grid in the substation area is obtained, including: The difference between the maximum load power of the power grid in the substation area and the total load power of the photovoltaic power grid connected to the power grid is taken as the maximum open capacity of the power grid in the substation area.

4. A method for evaluating the exploitable capacity of a distributed photovoltaic area according to claim 1, characterized in that: According to the difference between the power of users and photovoltaics in the preset historical time period of the substation, the photovoltaic consumption matching degree of the substation is obtained, including: Obtain a user total power sequence and a photovoltaic total power sequence, wherein the user total power sequence includes the user total power at each sampling moment within a preset historical time period of the area, and the photovoltaic total power sequence includes the photovoltaic total power at each sampling moment within a preset historical time period of the area; Obtaining the power difference at each sampling moment in the user's total power consumption sequence and the photovoltaic total power generation sequence, and obtaining the similarity between the user's total power consumption sequence and the photovoltaic total power generation sequence; The photovoltaic consumption matching degree of the metropolitan area is obtained according to the power difference and the similarity. The photovoltaic consumption matching degree of the metropolitan area is inversely proportional to the power difference and directly proportional to the similarity.

5. A method for evaluating the exploitable capacity of a distributed photovoltaic area as claimed in claim 4, characterized in that: The power difference is the absolute value of the power difference; the calculation formula for the photovoltaic consumption matching degree of the station area is: ； in, is the photovoltaic consumption matching degree of the station area, is the total power sequence of the user, is the total photovoltaic power generation sequence, For the The total power consumption of users at the sampling time, For the The total photovoltaic power generation at the sampling moment, is the similarity between the total power sequence of users and the total photovoltaic power generation sequence, is a linear normalization function, M is the number of sampling moments in the preset historical time period, For Negative correlation normalization.

6. A method for evaluating the exploitable capacity of a distributed photovoltaic area as claimed in claim 2, characterized in that: The process of obtaining the frequency instability of the power grid in the substation area includes: Obtaining the actual frequency of the user-side power grid at each sampling time within the target date; According to the difference between the actual frequency of the user-side power grid and the rated frequency of the power grid in the substation area at each sampling time within the target date, the frequency instability of the power grid in the substation area is obtained; The calculation formula of the frequency instability of the power grid in the substation area is as follows: ； in, The frequency instability of the power grid in the substation area is is the kth user in the target date The actual frequency of the user-side power grid at the sampling moment is is the rated frequency of the power grid in the substation area; The actual voltage of photovoltaic power generation at any sampling moment is obtained by: obtaining the actual voltage of each photovoltaic module in the area at the sampling moment, calculating the average value of the actual voltage of all photovoltaic modules in the area at the sampling moment, and taking it as the actual voltage of photovoltaic power generation at the sampling moment; The actual photovoltaic power generation voltage at each sampling time within the date is obtained, and then the average value of the actual photovoltaic power generation voltage at all sampling times within the date is calculated to obtain the actual average photovoltaic power generation voltage.

7. A method for evaluating the exploitable capacity of a distributed photovoltaic area according to claim 1, characterized in that: The process of obtaining the power grid capacity adjustment factor of the substation area includes: Normalizing the photovoltaic consumption matching degree of the substation area and the frequency instability of the power grid in the substation area respectively; The product of the normalized photovoltaic consumption matching degree of the substation and the normalized frequency instability of the power grid in the substation is calculated to obtain the power grid capacity adjustment factor of the substation.

8. A method for evaluating the exploitable capacity of a distributed photovoltaic area as claimed in claim 7, characterized in that: The maximum open capacity of the power grid in the substation area is adjusted according to the power grid capacity adjustment factor to obtain the photovoltaic capacity that can actually be connected to the power grid in the substation area, including: The calculation formula for the photovoltaic capacity that can actually be connected to the grid in the substation area is as follows: ； in, The actual photovoltaic capacity that can be connected to the power grid in the area. The maximum open capacity of the power grid in the area. is the grid capacity adjustment factor.

9. A method for evaluating the exploitable capacity of a distributed photovoltaic area according to claim 1, characterized in that: Before obtaining the maximum load power of the power grid in the area according to the power consumption of all users in the area, the method for evaluating the exploitable capacity of the distributed photovoltaic area further includes: Obtain the total photovoltaic power generation and total power consumption in the preset historical time period of the substation; Obtaining the maximum photovoltaic power generation in a single day within the preset historical time period, and obtaining the actual average photovoltaic power generation voltage on the date corresponding to the maximum photovoltaic power generation in a single day; If the total photovoltaic power generation is less than the total power consumption, and the actual average photovoltaic power generation voltage is within the preset photovoltaic power generation stable voltage range, the substation executes the step of obtaining the maximum load power of the substation power grid based on the power consumption of all users in the substation.

10. A system for evaluating the exploitable capacity of a distributed photovoltaic area, comprising: Memory and processor; The memory is connected to the processor; The memory is used to store program instructions; The processor is used to implement the method for evaluating the developable capacity of a distributed photovoltaic area according to any one of claims 1 to 9 when the program instructions are executed.

Images