A distributed photovoltaic access capacity calculation method and system considering outgoing line protection

Abstract

The present invention belongs to the technical field of distributed photovoltaics, and specifically relates to a distributed photovoltaic access capacity calculation method and system considering outgoing line protection, comprising: obtaining the topological structure of a distribution network whose outgoing lines include distributed photovoltaics; calculating a timed overcurrent protection value of the distributed photovoltaics according to the obtained topological structure; considering the timed overcurrent protection refusal caused by external pumping and the timed overcurrent protection malfunction caused by reverse action, determining the upper limit of the distributed photovoltaic short-circuit current that does not affect the protection action according to the obtained timed overcurrent protection value, and determining the access capacity boundary of the distributed photovoltaics.

Description

Technical Field

[0001] The present invention belongs to the technical field of distributed photovoltaics, and in particular relates to a method and system for calculating the access capacity of distributed photovoltaics taking outgoing line protection into consideration. Background Art

[0002] The statements in this section merely provide background information related to the present invention and do not necessarily constitute prior art.

[0003] The installed capacity of new energy sources has been growing year by year, especially the installed capacity of distributed photovoltaics and the access density in the distribution network has been growing rapidly. The access of distributed photovoltaics has a great impact on the reliability and sensitivity of the relay protection of the traditional distribution network. From the perspective of relay protection, the scope of the accessible capacity of distributed photovoltaics is directly related to the safe and stable operation of the distribution network.

[0004] According to the inventors' understanding, existing research on distributed photovoltaics has only conducted a qualitative analysis on the range of distributed photovoltaic access capacity of active distribution networks or single feeders, but has not considered the three-stage current protection of the feeder, and cannot guarantee the sensitivity and reliability of the original protection. Summary of the invention

[0005] In order to solve the above problems, the present invention proposes a distributed photovoltaic access capacity calculation method and system considering outgoing line protection, considering the influence of the external absorption effect and reverse effect of the active distribution network on the distribution network outgoing line timing overcurrent protection, quantifying the degree of influence, and determining the accessible capacity boundary of distributed photovoltaic in a single feeder, thereby effectively ensuring the safe and stable operation of the active distribution network.

[0006] According to some embodiments, a first solution of the present invention provides a method for calculating the access capacity of distributed photovoltaic power generation considering outgoing line protection, which adopts the following technical solution:

[0007] A method for calculating the access capacity of distributed photovoltaic power plants taking into account outgoing line protection includes:

[0008] Obtain the topological structure of the distribution network with distributed photovoltaic outgoing lines;

[0009] According to the obtained topological structure, the timed overcurrent protection value of the distributed photovoltaic is calculated;

[0010] Considering the refusal of the timed overcurrent protection caused by the external draw and the false operation of the timed overcurrent protection caused by the reverse action, the upper limit of the distributed photovoltaic short-circuit current that does not affect the protection action is determined according to the obtained timed overcurrent protection value, and the access capacity boundary of the distributed photovoltaic is determined.

[0011] As a further technical limitation, considering the sensitivity requirement when a two-phase short circuit occurs at the end of the line under the minimum operation mode of the system, the timed overcurrent protection value of the distributed photovoltaic for in, is the system phase voltage, Z s.min is the system equivalent impedance in the small mode, K sen is the sensitivity coefficient, Z L is the equivalent impedance of the entire line.

[0012] As a further technical limitation, the constraint condition for the correct action of the timing overcurrent protection caused by the external pumping effect is: in, The short-circuit current provided by the system side when a two-phase short circuit occurs at the end of the line. is the timed overcurrent protection setting value, is the short-circuit current of the photovoltaic power on the line flowing through the outgoing switch; where, Z s is the busbar equivalent impedance, Z L2 is the line impedance from the photovoltaic access point to the end of the line, Z L is the line impedance from the busbar to the end of the line, is the short-circuit current of distributed photovoltaic on the line.

[0013] As a further technical limitation, considering the reverse effect of distributed photovoltaics on the outgoing line switches, when a short-circuit fault occurs outside the line and the short-circuit current of the distributed photovoltaics on the line is less than the timed overcurrent protection setting of the distributed photovoltaics, it has no effect on the timed overcurrent protection; when the short-circuit current of the distributed photovoltaics on the line is greater than the timed overcurrent protection value of the distributed photovoltaics, it will cause the timed overcurrent protection to malfunction.

[0014] As a further technical limitation, in order to ensure that the reverse action of distributed photovoltaics will not cause the timing overcurrent protection to malfunction, the short-circuit current of all distributed photovoltaics in this line must be less than the protection setting value, that is, Among them, I pv is the photovoltaic short-circuit current, is the system phase voltage, Z s.min is the busbar equivalent impedance, Z L is the line impedance, K sen It is the sensitivity coefficient of timing overcurrent protection; it determines the maximum short-circuit current provided by photovoltaics from the perspective of the reverse action of distributed photovoltaics.

[0015] As a further technical limitation, based on the sensitivity requirements of the timed overcurrent protection when a two-phase short-circuit fault occurs at the end of the line, the two short-circuit current values ​​at the outgoing switch determined by the external absorption and reverse action of the distributed photovoltaic system are comprehensively considered, and the smaller value of the two short-circuit current values ​​is taken as the upper limit of the short-circuit current that the distributed photovoltaic system can provide.

[0016] As a further technical limitation, the maximum short-circuit current that distributed photovoltaics can provide is comprehensively considered from the external absorption effect and reverse effect of distributed photovoltaics. The photovoltaic rated current is determined according to the multiple relationship between the short-circuit current of the photovoltaic inverter and the rated current. Combined with the access capacity calculation formula Among them, U N is the rated line voltage, I N The PV rated current is used to determine the access capacity boundary of distributed PV.

[0017] According to some embodiments, a second solution of the present invention provides a distributed photovoltaic access capacity calculation system considering outgoing line protection, which adopts the following technical solution:

[0018] A distributed photovoltaic access capacity calculation system considering outgoing line protection includes:

[0019] An acquisition module configured to acquire a topological structure of a distribution network including distributed photovoltaics;

[0020] The calculation module is configured to calculate the timed overcurrent protection value of the distributed photovoltaic according to the obtained topological structure; consider the timed overcurrent protection refusal caused by the external pumping effect and the timed overcurrent protection malfunction caused by the reverse effect, and determine the upper limit of the distributed photovoltaic short-circuit current that does not affect the protection action according to the obtained timed overcurrent protection value, and determine the access capacity boundary of the distributed photovoltaic.

[0021] According to some embodiments, a third solution of the present invention provides a computer-readable storage medium, which adopts the following technical solution:

[0022] A computer-readable storage medium stores a program, which, when executed by a processor, implements the steps of the distributed photovoltaic access capacity calculation method considering outgoing line protection as described in the first solution of the present invention.

[0023] According to some embodiments, a fourth solution of the present invention provides an electronic device, which adopts the following technical solution:

[0024] An electronic device comprises a memory, a processor and a program stored in the memory and executable on the processor, wherein when the processor executes the program, the steps in the method for calculating the access capacity of distributed photovoltaic power generation taking into account outgoing line protection as described in the first solution of the present invention are implemented.

[0025] Compared with the prior art, the present invention has the following beneficial effects:

[0026] The present invention provides the mechanism of the external absorption and reverse action of distributed photovoltaic on the outgoing line current, and calculates the accessible capacity boundary of distributed photovoltaic in the distribution network according to the fixed value setting method and principle of distribution network protection; at the same time, considering the influence of three-stage current protection, the present invention quantitatively calculates the accessible capacity boundary of distributed photovoltaic in the active distribution network from the perspective of relay protection, clarifies the protection boundary for the distributed photovoltaic access capacity of the active distribution network, ensures the action reliability of relay protection, and further ensures the safe and reliable operation of the distribution network of the power system. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] The drawings in the specification that constitute a part of this embodiment are used to provide a further understanding of this embodiment. The schematic embodiments of this embodiment and their descriptions are used to explain this embodiment and do not constitute improper limitations on this embodiment.

[0028] Figure 1 This is a flow chart of a method for calculating the access capacity of distributed photovoltaic power generation taking into account outgoing line protection in Embodiment 1 of the present invention;

[0029] Figure 2 This is a structural diagram of a distribution network with distributed photovoltaic outgoing lines in the first embodiment of the present invention;

[0030] Figure 3 This is a system analysis diagram in which only the system side or only the photovoltaic power generation provides short-circuit current in the first embodiment of the present invention;

[0031] Figure 4 This is an analysis diagram of the impact of reverse action on protection in the first embodiment of the present invention;

[0032] Figure 5 The angle relationship when the photovoltaic power generation only generates reactive power in the first embodiment of the present invention;

[0033] Figure 6 The angle relationship when the photovoltaic only generates active power in the first embodiment of the present invention;

[0034] Figure 7 is Z in the first embodiment of the present invention L2 Access capacity when taking different values;

[0035] Figure 8 A topological diagram of a 10 kV line in Embodiment 1 of the present invention;

[0036] Fig. 9 A topological structure diagram of a simulation model for verifying the reverse direction in Embodiment 1 of the present invention;

[0037] Fig.10 This is a structural block diagram of a distributed photovoltaic access capacity calculation system taking outgoing line protection into consideration in Embodiment 2 of the present invention. DETAILED DESCRIPTION

[0038] The present invention will be further described below in conjunction with the accompanying drawings and embodiments.

[0039] It should be noted that the following detailed descriptions are exemplary and are intended to provide further explanation of the present application. Unless otherwise specified, all technical and scientific terms used herein have the same meanings as those commonly understood by those skilled in the art to which the present application belongs.

[0040] It should be noted that the terms used herein are only for describing specific embodiments and are not intended to limit exemplary embodiments according to the present invention. As used herein, unless the context clearly indicates otherwise, the singular form is also intended to include the plural form. In addition, it should be understood that when the terms "comprising" and / or "including" are used in this specification, it indicates the presence of features, steps, operations, devices, components and / or combinations thereof.

[0041] In the absence of conflict, the embodiments of the present invention and the features of the embodiments may be combined with each other.

[0042] Embodiment 1

[0043] Embodiment 1 of the present invention introduces a method for calculating the access capacity of distributed photovoltaic power generation taking into account outgoing line protection.

[0044] like Figure 1 A distributed photovoltaic access capacity calculation method considering outgoing line protection is shown, including:

[0045] Obtain the topological structure of the distribution network with distributed photovoltaic outgoing lines;

[0046] According to the obtained topological structure, the timed overcurrent protection value of the distributed photovoltaic is calculated;

[0047] Considering the refusal of the timed overcurrent protection caused by the external draw and the false operation of the timed overcurrent protection caused by the reverse action, the upper limit of the distributed photovoltaic short-circuit current that does not affect the protection action is determined according to the obtained timed overcurrent protection value, and the access capacity boundary of the distributed photovoltaic is determined.

[0048] In this embodiment, the influence of distributed photovoltaic on a single feeder in the active distribution network on the overcurrent protection of the feeder mainly includes external pumping and reverse action. When determining the feeder protection adaptation boundary according to the external pumping and reverse action of distributed photovoltaic, it is mainly considered whether the external pumping will cause the refusal of the timing overcurrent protection and whether the reverse action will cause the malfunction of the timing overcurrent protection.

[0049] like Figure 2 and Figure 3As shown in the figure, when determining the boundary of the distributed photovoltaic access capacity of the feeder based on the external draw effect of the distributed photovoltaic, the main consideration is that the external draw effect causes the timing overcurrent protection to refuse to operate. The constraint condition for the correct operation of the timing overcurrent protection is shown in formula (1); that is,

[0050]

[0051] in, The short-circuit current provided by the system side when a two-phase short circuit occurs at the end of the line. It is the setting value of timing overcurrent protection; is the short-circuit current of the photovoltaic power flowing through the outgoing switch on the line, and its calculation formula is shown in formula (2), that is:

[0052]

[0053] Among them, Z L2 is the line impedance from the photovoltaic access point to the end of the line, Z L is the line impedance from the busbar to the end of the line, is the short-circuit current of distributed photovoltaic on the line.

[0054] The value of the timed overcurrent protection setting is based on the sensitivity requirement when a two-phase short circuit occurs at the end of the line under the minimum operation mode. The calculation method is shown in formula (3), that is,

[0055]

[0056] Among them, Z s.min is the system equivalent impedance in the small mode, K sen is the sensitivity coefficient, Z L is the equivalent impedance of the entire line.

[0057] Formula (1), formula (2) and formula (3) can be used to obtain formula (4), which can be rearranged to obtain formula (5), namely:

[0058]

[0059]

[0060]

[0061] In formula (5), is the system phase voltage, θ is the angle

[0062] Get

[0063]

[0064] like Figure 4As shown, line 1 and line 2 are outgoing lines on the same busbar, and line 1 has distributed photovoltaic access. Provides short-circuit current for distributed photovoltaic power generation in line 1. When a short-circuit fault occurs in line 2, the short-circuit current provided by distributed photovoltaic power generation flows to the busbar. If it is less than the protection setting value, it will have no effect on the protection; if it is greater than the protection setting value, it will cause the protection to malfunction.

[0065] Since the timed overcurrent protection setting value of the outgoing line switch is the lowest and is most susceptible to the reverse action of photovoltaic power, the timed overcurrent protection of the outgoing line switch of line 1 is considered here.

[0066] The calculation method of the fixed value of the timed overcurrent protection is shown in formula (3). In order to ensure that the timed overcurrent protection is not affected by the reverse action of the photovoltaic, the photovoltaic short-circuit current must be less than the fixed value, that is, it must satisfy formula (7), that is,

[0067]

[0068] Among them I pv is the photovoltaic short-circuit current.

[0069] Let the system voltage The reference angle is 0, and the impedance angle of the system impedance and the line equivalent impedance is set to 66 degrees. If the photovoltaic power generation is only reactive during the short circuit fault, the angle θ is 24 degrees. Figure 5 As shown; if the photovoltaic power only generates active power during the short circuit fault, the angle θ is -66 degrees. Figure 6 shown.

[0070] Since the active and reactive power generated by photovoltaic power during short-circuit faults are between the above two cases, θ is between -66 degrees and 24 degrees. When the sensitivity coefficient is 1.3, the angle range obtained by formula (6) is -50.28 degrees to 50.28 degrees, so the value range of θ is -50.28 degrees to 24 degrees.

[0071] Change Z L2 The value of , draw in MATLAB the upper and lower limits of the overcurrent III protection setting The mapping relationship with θ is as follows Figure 7 As shown in the figure, with the increase of the angle θ, the photovoltaic capacity that can be connected to the feeder first decreases and then increases under the influence of external extraction. When θ is 0, the minimum value can be obtained.

[0072] When θ is 0 degrees, formula (6) can be simplified to formula (8), where is the system phase voltage, Z L2 K is the line impedance from the photovoltaic access point to the end of the line, sen It is the sensitivity coefficient of the timing overcurrent protection, which is generally greater than 1.3.

[0073]

[0074] Formula (8) can be written as formula (9), defining is the line short-circuit current, I pv is the photovoltaic short-circuit current.

[0075]

[0076] K sen When 1.3 is taken, it can be obtained from formula (9) that when the ratio of line short-circuit current to distributed photovoltaic short-circuit current is greater than 5, that is, when the distributed photovoltaic short-circuit current does not exceed 20% of the line short-circuit current, it can be ensured that the overcurrent stage III protection will not fail to operate.

[0077]

[0078]

[0079] From formula (7), we can get (10), and then we can get (11), where I L.min is the short-circuit current when a two-phase short circuit occurs at the end of the line under the small mode. From formula (10), it can be seen that when the ratio of the short-circuit current between the two phases at the end of the line under the small mode to the short-circuit current of the photovoltaic connected to this line is greater than the sensitivity coefficient, it can ensure that the timing overcurrent protection of this line is not affected by the photovoltaic. From formula (11), it can be seen that the sensitivity coefficient K sen When the value is 1.3, the photovoltaic short-circuit capacity does not exceed 77% of the short-circuit capacity at the end of the line under the small mode, which can ensure that the overcurrent stage III protection is not affected by the reverse action of the photovoltaic.

[0080] According to the external absorption effect and reverse effect of distributed photovoltaics, the access range of distributed photovoltaics can be defined. In order to ensure the reliability and sensitivity of protection, the intersection of the two access capacity ranges is taken as the final single feeder accessible distributed photovoltaic capacity.

[0081] Case Analysis

[0082] Taking a 10 kV outgoing line of a 35 kV substation as a typical scenario, the above-mentioned access capacity boundary formula is simulated and verified. The topology of this typical scenario is as follows: Figure 8 The key parameters and values ​​are shown in Table 1.

[0083] Table 1 Key parameter values ​​and units of a 35 kV substation

[0084]

[0085] According to the proposed access capacity boundary formula, the accessible distributed photovoltaic capacity is:

[0086]

[0087] I pv <2.32*20%=0.464(kA)

[0088] Considering that the short-circuit current provided by photovoltaic power generation is 1.2 times the rated current, the distributed photovoltaic capacity that can be connected is

[0089]

[0090] From the above settlement results, it can be seen that the accessible distributed photovoltaic capacity is 7.03MW.

[0091] In order to verify the correctness of the above calculation results, a simulation model was built on the PSCAD simulation platform and simulation verification was carried out.

[0092] The timed overcurrent protection setting of the outgoing switch is:

[0093]

[0094] The simulation results show that when the protection begins to fail to operate, the distributed photovoltaic access capacity is 6.75MW, and the calculation result error is 4.1%, which can meet the project needs.

[0095] According to the access capacity boundary formula proposed by the reverse action, the maximum short-circuit current allowed to be provided by distributed photovoltaics is

[0096] I pv <0.77*I L.min =0.77*1.195=0.92(kA)

[0097] Therefore, the maximum capacity of distributed photovoltaics allowed to be connected is

[0098]

[0099] The simulation results are consistent with the above calculation results.

[0100] This embodiment provides the mechanism of external absorption and reverse action of distributed photovoltaic on outgoing line current, and calculates the accessible capacity boundary of distributed photovoltaic in the distribution network according to the fixed value setting method and principle of distribution network protection; at the same time, considering the influence of three-stage current protection, the present invention quantitatively calculates the accessible capacity boundary of distributed photovoltaic in the active distribution network from the perspective of relay protection, clarifies the protection boundary for the distributed photovoltaic access capacity of the active distribution network, ensures the reliability of relay protection, and further ensures the safe and reliable operation of the distribution network of the power system.

[0101] Embodiment 2

[0102] Embodiment 2 of the present invention introduces a distributed photovoltaic access capacity calculation system taking outgoing line protection into consideration.

[0103] like Fig.10 A distributed photovoltaic access capacity calculation system considering outgoing line protection is shown, comprising:

[0104] An acquisition module configured to acquire a topological structure of a distribution network including distributed photovoltaics;

[0105] The calculation module is configured to calculate the timed overcurrent protection value of the distributed photovoltaic according to the obtained topological structure; consider the timed overcurrent protection refusal caused by the external pumping effect and the timed overcurrent protection malfunction caused by the reverse effect, and determine the upper limit of the distributed photovoltaic short-circuit current that does not affect the protection action according to the obtained timed overcurrent protection value, and determine the access capacity boundary of the distributed photovoltaic.

[0106] The detailed steps are the same as the method for calculating the distributed photovoltaic access capacity considering outgoing line protection provided in Example 1, and will not be repeated here.

[0107] Embodiment 3

[0108] Embodiment 3 of the present invention provides a computer-readable storage medium.

[0109] A computer-readable storage medium stores a program, which, when executed by a processor, implements the steps in the method for calculating the distributed photovoltaic access capacity considering outgoing line protection as described in the first embodiment of the present invention.

[0110] The detailed steps are the same as the method for calculating the distributed photovoltaic access capacity considering outgoing line protection provided in Example 1, and will not be repeated here.

[0111] Embodiment 4

[0112] A fourth embodiment of the present invention provides an electronic device.

[0113] An electronic device comprises a memory, a processor and a program stored in the memory and executable on the processor, wherein when the processor executes the program, the steps in the method for calculating the access capacity of distributed photovoltaic power generation taking into account outgoing line protection as described in the first embodiment of the present invention are implemented.

[0114] The detailed steps are the same as the method for calculating the distributed photovoltaic access capacity considering outgoing line protection provided in Example 1, and will not be repeated here.

[0115] The above description is only a preferred embodiment of the present embodiment and is not intended to limit the present embodiment. For those skilled in the art, the present embodiment may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present embodiment shall be included in the protection scope of the present embodiment.

Claims

1. A method for calculating the access capacity of distributed photovoltaic power generation considering outgoing line protection, characterized in that: include: Obtain the topological structure of the distribution network with distributed photovoltaic outgoing lines; According to the obtained topological structure, the timed overcurrent protection value of the distributed photovoltaic is calculated; Considering the refusal of the timing overcurrent protection caused by the external pumping action and the false operation of the timing overcurrent protection caused by the reverse action, the upper limit of the distributed photovoltaic short-circuit current that does not affect the protection action is determined according to the obtained timing overcurrent protection value, and the access capacity boundary of the distributed photovoltaic is determined; Considering the sensitivity requirement when a two-phase short circuit occurs at the end of the line under the minimum operation mode of the system, the timed overcurrent protection value of distributed photovoltaic for in, is the system phase voltage, Z s.min is the system equivalent impedance in the small mode, K sen is the sensitivity coefficient, Z L is the equivalent impedance of the entire line; Considering the constraints of the correct action of the timing overcurrent protection caused by the external pumping effect, in, The short-circuit current provided by the system side when a two-phase short circuit occurs at the end of the line. is the timed overcurrent protection setting value, is the short-circuit current of the photovoltaic power on the line flowing through the outgoing switch; where, Z s is the busbar equivalent impedance, Z L2 is the line impedance from the photovoltaic access point to the end of the line, Z L is the line impedance from the busbar to the end of the line, is the short-circuit current of distributed photovoltaic on the line; Considering the reverse effect of distributed photovoltaics on the outgoing line switch, when a short-circuit fault occurs outside the line, if the short-circuit current of the distributed photovoltaics on the line is less than the timed overcurrent protection setting value of the distributed photovoltaics, it will have no effect on the timed overcurrent protection; when the short-circuit current of the distributed photovoltaics on the line is greater than the timed overcurrent protection value of the distributed photovoltaics, it will cause the timed overcurrent protection to malfunction; To ensure that the reverse action of distributed photovoltaics does not cause the timing overcurrent protection to malfunction, the short-circuit current of all distributed photovoltaics in this line must be less than the protection setting value. Among them, I pv is the photovoltaic short-circuit current, is the system phase voltage, Z s.min is the busbar equivalent impedance, Z L is the line impedance, K sen is the sensitivity coefficient of the timing overcurrent protection; determines the maximum short-circuit current provided by the photovoltaic from the perspective of the reverse action of the distributed photovoltaic; According to the sensitivity requirements of the timing overcurrent protection when a two-phase short-circuit fault occurs at the end of the line, the two short-circuit current values ​​at the outgoing line switch determined by the external absorption and reverse action of the distributed photovoltaic are comprehensively considered, and the smaller value of the two short-circuit current values ​​is taken as the upper limit of the short-circuit current that the distributed photovoltaic can provide; Comprehensively consider the maximum short-circuit current that distributed photovoltaics can provide from the external absorption effect and reverse effect of distributed photovoltaics, determine the photovoltaic rated current according to the multiple relationship between the short-circuit current of the photovoltaic inverter and the rated current, and combine the access capacity calculation formula Among them, U N is the rated line voltage, I N The PV rated current is used to determine the access capacity boundary of distributed PV.

2. A distributed photovoltaic access capacity calculation system considering outgoing line protection, characterized in that: include: An acquisition module configured to acquire a topological structure of a distribution network including distributed photovoltaics; A calculation module is configured to calculate the timed overcurrent protection value of the distributed photovoltaic according to the obtained topological structure; considering the timed overcurrent protection refusal caused by the external pumping action and the timed overcurrent protection malfunction caused by the reverse action, and according to the obtained timed overcurrent protection value, determine the upper limit of the distributed photovoltaic short-circuit current that does not affect the protection action, and determine the access capacity boundary of the distributed photovoltaic; Considering the sensitivity requirement when a two-phase short circuit occurs at the end of the line under the minimum operation mode of the system, the timed overcurrent protection value of distributed photovoltaic for in, is the system phase voltage, Z s.min is the system equivalent impedance in the small mode, K sen is the sensitivity coefficient, Z L is the equivalent impedance of the entire line; Considering the constraints of the correct action of the timing overcurrent protection caused by the external pumping effect, in, The short-circuit current provided by the system side when a two-phase short circuit occurs at the end of the line. is the timed overcurrent protection setting value, is the short-circuit current of the photovoltaic power on the line flowing through the outgoing switch; where, Z s is the busbar equivalent impedance, Z L2 is the line impedance from the photovoltaic access point to the end of the line, Z L is the line impedance from the busbar to the end of the line, is the short-circuit current of distributed photovoltaic on the line; Considering the reverse effect of distributed photovoltaics on the outgoing line switch, when a short-circuit fault occurs outside the line, if the short-circuit current of the distributed photovoltaics on the line is less than the timed overcurrent protection setting value of the distributed photovoltaics, it will have no effect on the timed overcurrent protection; when the short-circuit current of the distributed photovoltaics on the line is greater than the timed overcurrent protection value of the distributed photovoltaics, it will cause the timed overcurrent protection to malfunction; To ensure that the reverse action of distributed photovoltaics does not cause the timing overcurrent protection to malfunction, the short-circuit current of all distributed photovoltaics in this line must be less than the protection setting value. Among them, I pv is the photovoltaic short-circuit current, is the system phase voltage, Z s.min is the busbar equivalent impedance, Z L is the line impedance, K sen is the sensitivity coefficient of the timing overcurrent protection; determines the maximum short-circuit current provided by the photovoltaic from the perspective of the reverse action of the distributed photovoltaic; According to the sensitivity requirements of the timing overcurrent protection when a two-phase short-circuit fault occurs at the end of the line, the two short-circuit current values ​​at the outgoing line switch determined by the external absorption and reverse action of the distributed photovoltaic are comprehensively considered, and the smaller value of the two short-circuit current values ​​is taken as the upper limit of the short-circuit current that the distributed photovoltaic can provide; Comprehensively consider the maximum short-circuit current that distributed photovoltaics can provide from the external absorption effect and reverse effect of distributed photovoltaics, determine the photovoltaic rated current according to the multiple relationship between the short-circuit current of the photovoltaic inverter and the rated current, and combine the access capacity calculation formula Among them, U N is the rated line voltage, I N The PV rated current is used to determine the access capacity boundary of distributed PV.

3. A computer-readable storage medium having a computer program stored thereon, characterized in that: When the program is executed by a processor, the distributed photovoltaic access capacity calculation method considering outgoing line protection as claimed in claim 1 is implemented.

4. An electronic device comprising a memory, a processor, and a computer program stored in the memory and executable on the processor, characterized in that: When the processor executes the program, the distributed photovoltaic access capacity calculation method considering outgoing line protection as claimed in claim 1 is implemented.

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