Evaluation method and device for bearing capacity of distributed power supply, computer equipment and program product

Abstract

The invention relates to a distributed power supply bearing capacity assessment method and device, computer equipment and a computer program product. The method comprises the following steps: establishing a mathematical model of output characteristics of a distributed power supply; based on the mathematical model, determining an evaluation index of the bearing capacity of the distributed power supply; connecting the distributed power supply into a power grid, and determining a reverse load rate in the power grid based on the thermal stability of the power grid; according to various different conditions occurring in thermal stability, short-circuit current checking, voltage deviation checking and harmonic checking in a power grid, the bearing capacity of the distributed power supply is evaluated as a corresponding grade. By adopting the method, the accuracy of evaluating the bearing capacity of the distributed power supply can be effectively improved.

Description

Technical Field

[0001] The present application relates to the technical field of data evaluation, and particularly to an evaluation method, device, computer device, computer-readable storage medium, and computer program product for the carrying capacity of distributed power sources. Background Art

[0002] With the rapid development of new energy power generation systems, the large-scale and widespread access of new energy mainly based on photovoltaic and wind power is an inevitable trend in the transformation and development of the power grid's energy. Due to the randomness and volatility of new energy power generation systems, and at the same time, there are problems such as unbalanced layout of new energy installations and reverse distribution of power generation and load, the access of distributed new energy will cause serious problems endangering the safe operation of the power grid, such as random fluctuations and frequency disorders in the power grid. Therefore, it is necessary to evaluate the ability of the power grid to carry distributed new energy power generation systems.

[0003] In the related art, in the process of studying the distribution network, only taking the impact of distributed new energy power generation systems on the power system as an index will result in the currently established model being insufficient, unable to comprehensively consider the impact of distributed new energy power generation systems on the power grid, and leading to inaccurate evaluation of the carrying capacity of distributed power sources in the end. Summary of the Invention

[0004] Based on this, in view of the above technical problems, it is necessary to provide an evaluation method, device, computer device, computer-readable storage medium, and computer program product for the carrying capacity of distributed power sources that can improve the accuracy of evaluating the carrying capacity of distributed power sources.

[0005] In a first aspect, the present application provides an evaluation method for the carrying capacity of distributed power sources, including:

[0006] Establish a mathematical model of the output characteristics of distributed power sources; the distributed power sources include solar thermal power generation systems, photovoltaic power generation systems, and wind power generation systems;

[0007] Based on the mathematical model, determine the evaluation indicators for the carrying capacity of distributed power sources; the evaluation indicators include thermal stability, short-circuit current check, voltage deviation check, and harmonic check;

[0008] Connect the distributed power sources to the power grid, and based on the thermal stability of the power grid, determine the reverse load rate in the power grid;

[0009] When at least one of the following conditions occurs in the power grid: reverse power injection of distributed power sources, reverse load rate greater than the preset range, failure to pass the short-circuit current check, failure to pass the voltage deviation check, or failure to pass the harmonic check, the evaluation level of the distributed power source carrying capacity is the first level; when the reverse load rate is within the preset range and passes the short-circuit current check, voltage deviation check, and harmonic check, the evaluation level of the distributed power source carrying capacity is the second level; when the reverse load rate is less than the preset range and passes the short-circuit current check, voltage deviation check, and harmonic check, the evaluation level of the distributed power source carrying capacity is the third level.

[0010] In one embodiment, determining the reverse load rate in the power grid based on the thermal stability of the power grid includes:

[0011] Determine the power of the distributed power sources in the power grid within a preset time period, the power of other power sources except the distributed power sources within the preset time period, and the power consumption load of the power grid within the preset time period;

[0012] Take the sum of the power of the distributed power sources in the power grid within the preset time period and the power of other power sources except the distributed power sources within the preset time period as the input power of the power grid within the preset time period;

[0013] Take the difference between the input power and the power consumption load as the remaining power of the power grid within the preset time period;

[0014] Take the ratio of the remaining power to the actual operating limit of the power grid as the reverse load rate of the power grid.

[0015] In one embodiment, the evaluation process of the short-circuit current check includes:

[0016] Before the distributed power source is connected to the power grid, when the short-circuit current at the peak load of the power grid does not exceed the short-circuit current limit, the first stage of the short-circuit current check evaluation passes;

[0017] After the distributed power source is connected to the power grid, determine the first current based on the short-circuit current at the peak load of the power grid, the newly added capacity in the power grid, and the rated voltage of the power grid bus. When the first current is less than the short-circuit current limit, the second stage of the short-circuit current check evaluation passes;

[0018] When both the first stage of the evaluation and the second stage of the evaluation pass, the short-circuit current check evaluation passes.

[0019] In one embodiment, the evaluation process of the voltage deviation check includes:

[0020] When the maximum positive voltage deviation in the power grid is less than the allowable value of the positive voltage deviation and the minimum negative voltage deviation is greater than the allowable value of the negative voltage deviation, the evaluation of the voltage deviation check is passed.

[0021] In one embodiment, the evaluation process of the harmonic check includes:

[0022] When the harmonic current in the power grid is less than the allowable value of the harmonic current and the interharmonic voltage content rate is less than the limit value of the interharmonic voltage content rate, the evaluation of the harmonic check is passed.

[0023] In one embodiment, the calculation formula for the additional capacity available in the power grid includes:

[0024] ;

[0025] Wherein, is the additional capacity available in the power grid, is the reverse load rate, is the actual operation limit of the power grid, is the preset margin coefficient.

[0026] In a second aspect, the present application also provides an evaluation device for the carrying capacity of distributed power sources, including:

[0027] A building module, configured to build a mathematical model of the output characteristics of distributed power sources; the distributed power sources include a solar thermal power generation system, a photovoltaic power generation system, and a wind power generation system;

[0028] A determination module, configured to determine an evaluation index for the carrying capacity of distributed power sources based on the mathematical model; the evaluation index includes thermal stability, short-circuit current check, voltage deviation check, and harmonic check;

[0029] The determination module is further configured to connect the distributed power source to the power grid and determine the reverse load rate in the power grid based on the thermal stability of the power grid;

[0030] An evaluation module, configured to set the evaluation level of the carrying capacity of the distributed power source to the first level when at least one of the following situations occurs in the power grid: power reverse of the distributed power source, reverse load rate greater than the preset range, short-circuit current check fails, voltage deviation check fails, or harmonic check fails; set the evaluation level of the carrying capacity of the distributed power source to the second level when the reverse load rate is within the preset range and the short-circuit current check, voltage deviation check, and harmonic check are passed; set the evaluation level of the carrying capacity of the distributed power source to the third level when the reverse load rate is less than the preset range and the short-circuit current check, voltage deviation check, and harmonic check are passed.

[0031] In a third aspect, the present application also provides a computer device, including a memory and a processor. The memory stores a computer program, and when the processor executes the computer program, the following steps are implemented:

[0032] Establish a mathematical model for the output characteristics of distributed power sources; the distributed power sources include a solar thermal power generation system, a photovoltaic power generation system, and a wind power generation system;

[0033] Based on the mathematical model, determine the evaluation indexes for the carrying capacity of distributed power sources; the evaluation indexes include thermal stability, short-circuit current check, voltage deviation check, and harmonic check;

[0034] Connect the distributed power source to the power grid, and based on the thermal stability of the power grid, determine the reverse load rate in the power grid;

[0035] When at least one of the following situations occurs in the power grid: reverse power transmission of distributed power sources, reverse load rate greater than the preset range, short-circuit current check fails, voltage deviation check fails, or harmonic check fails, the evaluation level of the carrying capacity of distributed power sources is the first level; when the reverse load rate is within the preset range and passes the short-circuit current check, voltage deviation check, and harmonic check, the evaluation level of the carrying capacity of distributed power sources is the second level; when the reverse load rate is less than the preset range and passes the short-circuit current check, voltage deviation check, and harmonic check, the evaluation level of the carrying capacity of distributed power sources is the third level.

[0036] In a fourth aspect, the present application also provides a computer-readable storage medium, on which a computer program is stored. When the computer program is executed by a processor, the following steps are implemented:

[0037] Establish a mathematical model for the output characteristics of distributed power sources; the distributed power sources include a solar thermal power generation system, a photovoltaic power generation system, and a wind power generation system;

[0038] Based on the mathematical model, determine the evaluation indexes for the carrying capacity of distributed power sources; the evaluation indexes include thermal stability, short-circuit current check, voltage deviation check, and harmonic check;

[0039] Connect the distributed power source to the power grid, and based on the thermal stability of the power grid, determine the reverse load rate in the power grid;

[0040] When at least one of the following situations occurs in the power grid: reverse power flow of distributed power sources, reverse load rate greater than the preset range, short-circuit current check fails, voltage deviation check fails, or harmonic check fails, the evaluation level of the distributed power source carrying capacity is the first level; when the reverse load rate is within the preset range and passes the short-circuit current check, voltage deviation check, and harmonic check, the evaluation level of the distributed power source carrying capacity is the second level; when the reverse load rate is less than the preset range and passes the short-circuit current check, voltage deviation check, and harmonic check, the evaluation level of the distributed power source carrying capacity is the third level.

[0041] Fifthly, the present application also provides a computer program product, including a computer program, which when executed by a processor implements the following steps:

[0042] Establish a mathematical model of the output characteristics of distributed power sources; the distributed power sources include a solar thermal power generation system, a photovoltaic power generation system, and a wind power generation system;

[0043] Based on the mathematical model, determine the evaluation indexes of the distributed power source carrying capacity; the evaluation indexes include thermal stability, short-circuit current check, voltage deviation check, and harmonic check;

[0044] Connect the distributed power source to the power grid, and based on the thermal stability of the power grid, determine the reverse load rate in the power grid;

[0045] When at least one of the following situations occurs in the power grid: reverse power flow of distributed power sources, reverse load rate greater than the preset range, short-circuit current check fails, voltage deviation check fails, or harmonic check fails, the evaluation level of the distributed power source carrying capacity is the first level; when the reverse load rate is within the preset range and passes the short-circuit current check, voltage deviation check, and harmonic check, the evaluation level of the distributed power source carrying capacity is the second level; when the reverse load rate is less than the preset range and passes the short-circuit current check, voltage deviation check, and harmonic check, the evaluation level of the distributed power source carrying capacity is the third level.

[0046] The above evaluation method, device, computer equipment, computer-readable storage medium and computer program product for the carrying capacity of distributed power sources first establish a mathematical model for the output characteristics of distributed power sources; based on the mathematical model, determine the evaluation indexes for the carrying capacity of distributed power sources; connect the distributed power sources to the power grid, and based on the thermal stability of the power grid, determine the reverse load rate in the power grid; when at least one of the situations of power reverse flow of distributed power sources, reverse load rate greater than the preset range, failure of short-circuit current check, failure of voltage deviation check or failure of harmonic check occurs in the power grid, the evaluation level of the carrying capacity of distributed power sources is the first level; when the reverse load rate is within the preset range and the short-circuit current check, voltage deviation check and harmonic check are passed, the evaluation level of the carrying capacity of distributed power sources is the second level; when the reverse load rate is less than the preset range and the short-circuit current check, voltage deviation check and harmonic check are passed, the evaluation level of the carrying capacity of distributed power sources is the third level. In this way, by analyzing the characteristics of three types of distributed power sources, namely photovoltaic, wind power and solar thermal power generation, the evaluation indexes are determined, so that the results determined by the evaluation indexes are more accurate. Brief Description of the Drawings

[0047] In order to more clearly illustrate the technical solutions in the embodiments of the present application or related technologies, the following will briefly introduce the drawings required for use in the description of the embodiments of the present application or related technologies. Obviously, the drawings in the following description are only some embodiments of the present application. For those of ordinary skill in the art, other related drawings can be obtained based on these drawings without creative efforts.

[0048] Figure 1 It is an application environment diagram of the evaluation method for the carrying capacity of distributed power sources in an embodiment;

[0049] Figure 2 It is a schematic flowchart of the evaluation method for the carrying capacity of distributed power sources in an embodiment;

[0050] Figure 3 It is a structural block diagram of the evaluation device for the carrying capacity of distributed power sources in an embodiment;

[0051] Figure 4 It is an internal structure diagram of computer equipment in an embodiment. Detailed Description of the Embodiments

[0052] In order to make the purpose, technical solutions and advantages of the present application clearer, the following further details the present application in conjunction with the drawings and embodiments. It should be understood that the specific embodiments described here are only used to explain the present application and are not used to limit the present application.

[0053] The evaluation method for the carrying capacity of distributed power sources provided by the embodiments of the present application can be applied to such asFigure 1 In the application environment shown. Among them, the terminal 102 communicates with the server 104 through the network. The data storage system can store the data that the server 104 needs to process. The data storage system can be integrated on the server 104, or can be placed on the cloud or other network servers. Among them, the terminal 102 can be but is not limited to various personal computers, laptop computers, smart phones, tablet computers, Internet of Things devices, and portable wearable devices. The Internet of Things devices can be smart speakers, smart TVs, smart air conditioners, smart in-vehicle devices, projection devices, etc. The portable wearable devices can be smart watches, smart bracelets, head-mounted devices, etc. The head-mounted devices can be virtual reality (VR) devices, augmented reality (AR) devices, smart glasses, etc. The server 104 can be an independent physical server, or a server cluster or distributed system composed of multiple physical servers, or a cloud server that provides cloud computing services.

[0054] In an exemplary embodiment, as Figure 2 shown, a method for evaluating the distributed power carrying capacity is provided. Taking the terminal 102 in Figure 1 as an example, the method includes the following steps 202 to step 208. Among them:

[0055] Step 202, establish a mathematical model of the output characteristics of distributed power.

[0056] Among them, the distributed power includes a solar thermal power generation system, a photovoltaic power generation system, and a wind power generation system.

[0057] Exemplarily, the power balance expression of a solar thermal power station is shown in formula (1).

[0058] (1)

[0059] Among them, is the thermal power transferred by the concentrating and heat collecting system to the heat transfer and heat storage medium; is the thermal power transferred by the heat transfer and heat storage medium to the heat exchange system, is the thermal power transferred by the heat transfer and heat storage medium to the heat storage system, is the thermal power transferred by the heat storage system to the heat transfer and heat storage medium.

[0060] The thermal power converted from light energy by the concentrating and heat collecting system is specifically calculated as shown in formula (2).

[0061] (2)

[0062] Among them, is the thermal power concentrated by the concentrating and heat collecting system; Represents the conversion efficiency between light energy and heat energy, Represents the area for absorbing light energy, Represents the light intensity.

[0063] Under normal circumstances, the actual reference of a solar thermal power station will consider the curtailment power. The actual thermal power used by the system needs to take the curtailment power into account, and the specific calculation is shown in formula (3).

[0064] (3)

[0065] Wherein, is the curtailment power of the solar thermal power station;

[0066] Meanwhile, there is heat energy loss in the main body of the solar thermal power generation system during the heat charging and discharging processes, and the calculation of the thermal power loss is shown in formula (4).

[0067] (4)

[0068] Wherein, is the thermal power during charging, represents the thermal power during discharging, represents the heat dissipation of the heat storage system, and the specific calculation formula is shown in (5).

[0069] (5)

[0070] Wherein, is the consumption coefficient, is the time interval, is the total heat storage power in the heat storage system at time

[0071] The specific formula of the mathematical model for the output characteristics of the solar thermal power generation system is shown in (6).

[0072] (6)

[0073] Wherein, 、 、 、 、 、 are usually determined by the parameters of the solar thermal power generation system itself, and are the generator coefficients of the solar thermal power station. x and y represent the sectional coefficients, is the minimum generator power, is the maximum generator set power.

[0074] Exemplarily, the U-I characteristics of a solar photovoltaic panel are specifically shown in formula (7).

[0075] (7)

[0076] In the formula, is the output voltage of the system, represents the output current of the system; represents the photocurrent generated in the photon reaction, represents the reverse saturation leakage current flowing through the diode; represents the electric charge quantity; represents the equivalent series impedance, represents the equivalent parallel impedance; A is determined by the properties of the diode itself, k is a constant, and T represents the temperature of the photovoltaic power generation panel.

[0077] Because is usually much smaller than the photocurrent and R S is much smaller than the forward conduction impedance of the one-way diode, so in formula (7) can be ignored and let I sh = I sc ; in the open circuit state, I = 0, U = U OC At the same time, when near the maximum power point, U = U m , I = I m . Formulas (8) and (9) are obtained. By simplifying the quantities in formula (7) that are affected by photovoltaics in the solar photovoltaic panel, formula (8) is obtained:

[0078] (8)

[0079] (9)

[0080] Among them, the magnitudes of the parameters C1 and C2 can be calculated through the basic parameters of the photovoltaic cell obtained, the short-circuit current , open-circuit voltage , maximum power point voltage and current and thereby determine the U-I characteristic curve of the photovoltaic panel, and the mathematical model of the photovoltaic power generation output characteristic is U*I.

[0081] Exemplarily, the magnitude of wind power generation output is usually related to the wind speed magnitude and blade opening degree during that period. The Weibull probability distribution can well represent the wind speed change curve during a certain period, and the specific calculation is shown in formula (10).

[0082] (10)

[0083] Among them, v represents the wind speed of the measured target area; k represents the Weibull distribution corresponding to the wind speed distribution characteristics of this area. When k = 2, the wind speed distribution in the area shows a classic Rayleigh distribution; c represents the magnitude of the wind speed in this area during the current period.

[0084] The functional relationship between the wind speed v and the output of the wind turbine is specifically shown in formula (11).

[0085] (11)

[0086] Among them, is the output magnitude of the i-th wind turbine at time t; represents the rated power of the wind turbine; is the actual wind speed of this wind turbine at time t; is the cut-in wind speed of this wind turbine, is the cut-out wind speed of this wind turbine, is the rated wind speed of this wind turbine. Among them, , .

[0087] The mathematical model of the output characteristics of the wind power generation system can be obtained as shown in formula (12).

[0088] (12)

[0089] In the formula, N i represents the number of wind turbines in the wind farm.

[0090] Step 204: Based on the mathematical model, determine the evaluation index of the distributed power source carrying capacity.

[0091] Among them, the evaluation indexes include thermal stability, short-circuit current check, voltage deviation check and harmonic check.

[0092] Optionally, the rapid penetration of distributed energy generation makes the operation and maintenance management of the power system grid more complex. The form of distributed power sources accessing the grid is mainly regional distributed power sources, and the access of regional distributed generation power sources will affect the power flow distribution downstream of the grid to a certain extent, and even result in incorrect power direction and reverse power flow overstepping the line, leading to changes in load characteristics. Therefore, thermal stability is used as one of the evaluation indexes of the distributed power source carrying capacity.

[0093] Optionally, according to the composition of distributed power source installations, power and electricity balance capabilities, voltage levels and control capabilities, and power quality problems, the evaluation indexes of distributed power source carrying capacity are determined as short-circuit current check, voltage deviation check and harmonic check.

[0094] Step 206: Connect the distributed power source to the power grid, and determine the reverse load rate in the power grid based on the thermal stability of the power grid.

[0095] Among them, the reverse load rate refers to the ratio of the power fed back to the power grid to the rated capacity of the transformer or line when the output of distributed power sources such as photovoltaic power generation exceeds the actual load of the transformer or line after the distributed power source is connected to the power grid.

[0096] Exemplarily, determine the power of the distributed power source in the power grid within a preset time period, the power of other power sources except the distributed power source within the preset time period, and the power consumption load of the power grid within the preset time period; use the sum of the power of the distributed power source in the power grid within the preset time period and the power of other power sources except the distributed power source within the preset time period as the input power of the power grid within the preset time period; use the difference between the input power and the power consumption load as the remaining power of the power grid within the preset time period; use the ratio of the remaining power to the actual operation limit value of the power grid as the reverse load rate of the power grid.

[0097] Step 208: When at least one of the following situations occurs in the power grid: power reverse transmission of the distributed power source, reverse load rate greater than the preset range, short-circuit current check fails, voltage deviation check fails, or harmonic check fails, the evaluation level of the distributed power source's carrying capacity is the first level; when the reverse load rate is within the preset range and passes the short-circuit current check, voltage deviation check, and harmonic check, the evaluation level of the distributed power source's carrying capacity is the second level; when the reverse load rate is less than the preset range and passes the short-circuit current check, voltage deviation check, and harmonic check, the evaluation level of the distributed power source's carrying capacity is the third level.

[0098] Optionally, evaluate the evaluation indicators in the power grid. When at least one of the following situations occurs in the power grid: power reverse transmission of the distributed power source, reverse load rate greater than the preset range, short-circuit current check fails, voltage deviation check fails, or harmonic check fails, the evaluation level of the distributed power source's carrying capacity is the first level;

[0099] Among them, the first level means that the local consumption condition of the distributed power source is insufficient, the thermal stability of the transformer or line alarms, and there are safety risks in the power grid.

[0100] When the reverse load rate is within the preset range and passes the short-circuit current check, voltage deviation check, and harmonic check, the evaluation level of the distributed power source's carrying capacity is the second level;

[0101] Among them, the second level means that the reverse load of the transformer or line does not reach the warning value and the access condition is good.

[0102] When the reverse load rate is less than the preset range and passes the short-circuit current check, voltage deviation check, and harmonic check, the evaluation level of the distributed power source carrying capacity is the third level.

[0103] Among them, the third level means that there is no reverse load on the transformer or line, and the absorption conditions of the distributed power source are relatively good.

[0104] Among them, the first level, the second level, and the third level are artificially divided levels, which can be divided by the user according to the actual situation, and the embodiments of the present application do not limit this.

[0105] For example, when evaluating the evaluation index in the power grid, when at least one of the following situations occurs in the power grid: reverse power flow of the distributed power source, reverse load rate greater than the preset range, short-circuit current check fails, voltage deviation check fails, or harmonic check fails, the evaluation level of the distributed power source carrying capacity is red;

[0106] When the reverse load rate is within the preset range and passes the short-circuit current check, voltage deviation check, and harmonic check, the evaluation level of the distributed power source carrying capacity is yellow;

[0107] When the reverse load rate is less than the preset range and passes the short-circuit current check, voltage deviation check, and harmonic check, the evaluation level of the distributed power source carrying capacity is green.

[0108] In the above evaluation method for the distributed power source carrying capacity, a mathematical model of the output characteristics of the distributed power source is established; based on the mathematical model, the evaluation index of the distributed power source carrying capacity is determined; the distributed power source is connected to the power grid, and based on the thermal stability of the power grid, the reverse load rate in the power grid is determined; when at least one of the following situations occurs in the power grid: reverse power flow of the distributed power source, reverse load rate greater than the preset range, short-circuit current check fails, voltage deviation check fails, or harmonic check fails, the evaluation level of the distributed power source carrying capacity is the first level; when the reverse load rate is within the preset range and passes the short-circuit current check, voltage deviation check, and harmonic check, the evaluation level of the distributed power source carrying capacity is the second level; when the reverse load rate is less than the preset range and passes the short-circuit current check, voltage deviation check, and harmonic check, the evaluation level of the distributed power source carrying capacity is the third level. In this way, by analyzing the characteristics of the three types of distributed power sources, namely photovoltaic, wind power, and solar thermal power generation, the evaluation index is determined, so that the result determined by the evaluation index is more accurate.

[0109] In an exemplary embodiment, determining the reverse load rate in the power grid based on the thermal stability of the power grid includes: determining the power of distributed power sources in the power grid within a preset period, the power of other power sources except distributed power sources within the preset period, and the power consumption load of the power grid within the preset period; taking the sum of the power of distributed power sources in the power grid within the preset period and the power of other power sources except distributed power sources within the preset period as the input power of the power grid within the preset period; taking the difference between the input power and the power consumption load as the remaining power of the power grid within the preset period; and taking the ratio of the remaining power to the actual operation limit value of the power grid as the reverse load rate of the power grid.

[0110] In actual implementation, determining the power of distributed power sources in the power grid within a preset period , and the power of other power sources except distributed power sources within the preset period and the power consumption load of the power grid within the preset period ; taking the sum of the power of distributed power sources in the power grid within the preset period and the power of other power sources except distributed power sources within the preset period as the input power of the power grid within the preset period; taking the difference between the input power and the power consumption load as the remaining power of the power grid within the preset period; taking the ratio of the remaining power to the actual operation limit value of the power grid as the reverse load rate of the power grid, and the specific calculation formula is as shown in (13).

[0111] (13)

[0112] Wherein, is the reverse load rate, is the power of distributed power sources in the power grid within the preset period t, is the power of other power sources except distributed power sources within the preset period t, is the power consumption load of the power grid within the preset period t, is the power flowing from the distributed power source to the user side (such as the distribution network or end user) of the transformer or line within the preset period t.

[0113] In the above embodiment, by calculating the reverse load rate of the distributed power source, it is possible to accurately evaluate whether the equipment is overloaded, overheated, or even damaged. Through calculation, potential overload risks can be discovered in advance and measures can be taken to avoid equipment damage.

[0114] In an exemplary embodiment, the evaluation process of short-circuit current verification includes: before the distributed power source is connected to the power grid, when the short-circuit current at the peak load of the power grid does not exceed the short-circuit current limit value, the first stage of the evaluation of short-circuit current verification passes; after the distributed power source is connected to the power grid, based on the short-circuit current at the peak load of the power grid, the additional capacity that can be added to the power grid, and the rated voltage of the power grid bus, the first current is determined. When the first current is less than the short-circuit current limit value, the second stage of the evaluation of short-circuit current verification passes; when both the first stage and the second stage of the evaluation pass, the evaluation of short-circuit current verification passes.

[0115] In actual implementation, before the distributed power source is connected to the power grid, when the short-circuit current at the peak load of the power grid does not exceed the short-circuit current limit value, the first stage of the evaluation of short-circuit current verification passes, and the specific formula is shown in (14).

[0116] (14)

[0117] Among them, is the short-circuit current at the peak load of the power grid, is the short-circuit current limit value.

[0118] After the distributed power source is connected to the power grid, based on the short-circuit current at the peak load of the power grid, the additional capacity that can be added to the power grid, and the rated voltage of the power grid bus, the first current is determined. When the first current is less than the short-circuit current limit value, the second stage of the evaluation of short-circuit current verification passes, and the specific formula is shown in (15).

[0119] (15)

[0120] Among them, is the additional capacity that can be added to the power grid, is the rated voltage of the power grid bus.

[0121] When both the first stage and the second stage of the evaluation pass, the evaluation of the short-circuit current verification of the distributed power source passes.

[0122] In the above embodiment, by evaluating the short-circuit current verification, it can be determined whether the maximum current borne by the equipment (such as transformers, circuit breakers, buses, etc.) is within the rated short-circuit withstand capacity of the equipment when a short-circuit fault occurs. If the short-circuit current exceeds the rated value of the equipment, it may cause equipment damage and even trigger more serious accidents.

[0123] In an exemplary embodiment, the evaluation process of voltage deviation verification includes: when the positive voltage deviation extreme value in the power grid is less than the positive voltage deviation allowable value and the negative voltage deviation extreme value is greater than the negative voltage deviation allowable value, the evaluation of voltage deviation verification passes.

[0124] In actual implementation, the voltage deviation caused by the connection of distributed power sources to the power grid is calculated, and the specific calculation formula is shown in (16).

[0125] (16)

[0126] Among them, is the voltage deviation, is the resistance value in the power grid, is the increment of active power injected after the distributed power source is connected to the power grid, is the reactance value of the power grid, is the increment of reactive power injected after the distributed power source is connected to the power grid.

[0127] In the case where the positive voltage deviation extreme value in the power grid is less than the allowable value of the positive voltage deviation and the negative voltage deviation extreme value is greater than the allowable value of the negative voltage deviation, the evaluation of the voltage deviation check passes, and the specific formula is shown in (17).

[0128] (17)

[0129] Among them, is the positive voltage deviation extreme value, is the allowable value of the positive voltage deviation, is the negative voltage deviation extreme value, is the allowable value of the negative voltage deviation.

[0130] In the above embodiments, through the evaluation of the voltage deviation check, it can be ensured that the equipment operates within the specified voltage range, avoiding premature aging and damage of the equipment caused by voltage deviation, thereby extending the service life of the equipment.

[0131] In an exemplary embodiment, the evaluation process of harmonic check includes: when the harmonic current in the power grid is less than the allowable value of the harmonic current and the inter-harmonic voltage content rate is less than the limit value of the inter-harmonic voltage content rate, the evaluation of the harmonic check passes.

[0132] In actual implementation, when the harmonic current in the power grid is less than the allowable value of the harmonic current, the specific verification formula is shown in (18), and the inter-harmonic voltage content rate is also less than the limit value of the inter-harmonic voltage content rate, the specific verification formula is shown in (19), and the evaluation of the harmonic check passes.

[0133] (18)

[0134] (19)

[0135] Among them, is the harmonic current in the power grid, is the allowable value of the harmonic current, is the content ratio of interharmonic voltage, is the limit value of the content ratio of interharmonic voltage.

[0136] In the above embodiments, harmonic currents and voltages may cause overheating and damage to equipment. Through harmonic checking and assessment, it can be ensured that the equipment operates under the specified harmonic levels, avoiding equipment damage caused by harmonics. Through harmonic checking and assessment, the additional thermal stress generated by the equipment due to harmonics can be reduced, thereby extending the service life of the equipment.

[0137] In an exemplary embodiment, the calculation formula for the additional capacity that can be added to the power grid includes:

[0138] ;

[0139] wherein, is the additional capacity that can be added to the power grid, is the reverse load rate, is the actual operation limit of the power grid, is the preset margin coefficient.

[0140] In the above embodiments, calculating the additional capacity that can be added to the power grid helps to support the reasonable access of distributed power sources and improve power supply reliability.

[0141] To illustrate in detail the evaluation method for the carrying capacity of distributed power sources in this application, an embodiment will be used for illustration below. Exemplarily, this application illustrates the evaluation method for the carrying capacity of distributed power sources in a specific scenario.

[0142] Establish a mathematical model for the output characteristics of distributed power sources. Among them, distributed power sources include solar thermal power generation systems, photovoltaic power generation systems, and wind power generation systems.

[0143] The specific formula for the mathematical model of the output characteristics of the solar thermal power generation system is shown in (6), the mathematical model of the photovoltaic power generation output characteristics is U*I, and the mathematical model of the output characteristics of the wind power generation system is shown in formula (12).

[0144] The rapid penetration of distributed energy generation makes the operation and maintenance management of the power grid in the power system more complex. The form of distributed power sources accessing the power grid is mainly regional distributed power sources, and the access of regional distributed generation power sources will affect the power flow distribution downstream of the power grid to a certain extent, and even result in incorrect power directions and reverse power flow overstepping the line, leading to changes in load characteristics. Therefore, thermal stability is used as one of the evaluation indicators for the carrying capacity of distributed power sources.

[0145] Optionally, according to the composition of distributed power source installations, power and electricity balance capabilities, voltage levels, control capabilities, and power quality issues, the evaluation indicators for the carrying capacity of distributed power sources are determined as short-circuit current checking, voltage deviation checking, and harmonic checking.

[0146] Determine the power of distributed power sources in the power grid during a preset period, as well as the power of other power sources except distributed power sources and the power consumption load of the power grid during the preset period; take the sum of the power of distributed power sources in the power grid during the preset period and the power of other power sources except distributed power sources during the preset period as the input power of the power grid during the preset period; take the difference between the input power and the power consumption load as the remaining power of the power grid during the preset period; take the ratio of the remaining power to the actual operation limit value of the power grid as the reverse load rate of the power grid.

[0147] Evaluate the evaluation index in the power grid. When at least one of the following situations occurs in the power grid: reverse power transmission of distributed power source power, reverse load rate greater than the preset range, short-circuit current check fails, voltage deviation check fails, or harmonic check fails, the evaluation level of the distributed power source carrying capacity is the first level;

[0148] Among them, the first level means that the local consumption condition of the distributed power source is insufficient, the thermal stability of the transformer or line alarms, and there are safety risks in the power grid.

[0149] When the reverse load rate is within the preset range and passes the short-circuit current check, voltage deviation check, and harmonic check, the evaluation level of the distributed power source carrying capacity is the second level;

[0150] Among them, the second level means that the reverse load of the transformer or line does not reach the warning value and the access condition is good.

[0151] When the reverse load rate is less than the preset range and passes the short-circuit current check, voltage deviation check, and harmonic check, the evaluation level of the distributed power source carrying capacity is the third level.

[0152] Among them, the third level means that there is no reverse load on the transformer or line and the consumption condition of the distributed power source is relatively good.

[0153] This application further analyzes the output characteristics of several common distributed generation systems to more accurately describe the carrying capacity of the system for distributed power sources, and in subsequent work, the factors affecting the carrying capacity of the power system for distributed generation systems are concretely divided into different factors. By calculating and processing each factor, the carrying capacity of the power system is clearly divided into three levels, and the carrying capacity of the power system is more clearly determined.

[0154] It should be understood that although the steps in the flowcharts involved in the above-described embodiments are shown in sequence according to the arrows, these steps are not necessarily executed in the order indicated by the arrows. Unless there is a clear indication in this article, there is no strict order limit for the execution of these steps, and these steps can be executed in other orders. Moreover, at least some of the steps in the flowcharts involved in the above-described embodiments may include multiple steps or multiple stages. These steps or stages are not necessarily executed at the same time, but can be executed at different times. The execution order of these steps or stages is not necessarily sequential, but can be executed alternately or in turn with at least some of the steps or stages in other steps or other steps.

[0155] Based on the same inventive concept, an embodiment of the present application further provides an evaluation device for the distributed power carrying capacity for implementing the evaluation method of the distributed power carrying capacity involved above. The solution provided by this device for solving problems is similar to the solution described in the above method. Therefore, the specific limitations in one or more embodiments of the evaluation device for the distributed power carrying capacity provided below can refer to the limitations on the evaluation method of the distributed power carrying capacity in the above text, and will not be repeated here.

[0156] In an exemplary embodiment, as Figure 3 shown, an evaluation device for the distributed power carrying capacity is provided, including: a establishment module 301, a determination module 302, and an evaluation module 303, where:

[0157] The establishment module is used to establish a mathematical model of the output characteristics of the distributed power source; the distributed power source includes a solar thermal power generation system, a photovoltaic power generation system, and a wind power generation system.

[0158] The determination module is used to determine the evaluation index of the distributed power carrying capacity based on the mathematical model; the evaluation index includes thermal stability, short-circuit current check, voltage deviation check, and harmonic check.

[0159] The determination module is further used to connect the distributed power source to the power grid and determine the reverse load rate in the power grid based on the thermal stability of the power grid.

[0160] An evaluation module is used to determine that when at least one of the following situations occurs in the power grid: reverse power flow of distributed power sources, reverse load rate greater than a preset range, short-circuit current verification fails, voltage deviation verification fails, or harmonic verification fails, the evaluation level of the distributed power source carrying capacity is the first level; when the reverse load rate is within the preset range and the short-circuit current verification, voltage deviation verification, and harmonic verification are passed, the evaluation level of the distributed power source carrying capacity is the second level; when the reverse load rate is less than the preset range and the short-circuit current verification, voltage deviation verification, and harmonic verification are passed, the evaluation level of the distributed power source carrying capacity is the third level.

[0161] In some embodiments, the above-mentioned determination module is further used to determine the power of the distributed power source in the power grid within a preset period, the power of other power sources except the distributed power source within the preset period, and the power consumption load of the power grid within the preset period;

[0162] The sum of the power of the distributed power source in the power grid within the preset period and the power of other power sources except the distributed power source within the preset period is used as the input power of the power grid within the preset period;

[0163] The difference between the input power and the power consumption load is used as the remaining power of the power grid within the preset period;

[0164] The ratio of the remaining power to the actual operating limit of the power grid is used as the reverse load rate of the power grid.

[0165] In some embodiments, the above-mentioned evaluation module is further used to determine that when the short-circuit current at the peak load of the power grid does not exceed the short-circuit current limit before the distributed power source is connected to the power grid, the first stage of the short-circuit current verification passes;

[0166] After the distributed power source is connected to the power grid, based on the short-circuit current at the peak load of the power grid, the newly added capacity in the power grid, and the rated voltage of the power grid bus, a first current is determined. When the first current is less than the short-circuit current limit, the second stage of the short-circuit current verification passes;

[0167] When both the first stage of the evaluation and the second stage of the evaluation pass, the evaluation of the short-circuit current verification passes.

[0168] In some embodiments, the above-mentioned evaluation module is further used to determine that when the positive voltage deviation extreme value in the power grid is less than the positive voltage deviation allowable value and the negative voltage deviation extreme value is greater than the negative voltage deviation allowable value, the evaluation of the voltage deviation verification passes.

[0169] In some embodiments, the above-mentioned evaluation module is further used to determine that when the harmonic current in the power grid is less than the harmonic current allowable value and the inter-harmonic voltage content rate is less than the inter-harmonic voltage content rate limit, the evaluation of the harmonic verification passes.

[0170] In some embodiments, the device further includes a calculation module for calculating the additional capacity that can be added to the power grid, including:

[0171] ;

[0172] Wherein, is the additional capacity that can be added to the power grid, is the reverse load rate, is the actual operating limit of the power grid, is a preset margin coefficient.

[0173] Each module in the above-mentioned evaluation device for the carrying capacity of distributed power sources can be implemented in whole or in part by software, hardware, and their combination. Each of the above modules can be embedded in or independent of the processor in the computer device in the form of hardware, or stored in the memory of the computer device in the form of software, so that the processor can call and execute the operations corresponding to each of the above modules.

[0174] In an exemplary embodiment, a computer device is provided. The computer device can be a server, and its internal structure diagram can be as shown in Figure 4 The computer device includes a processor, a memory, an input / output interface (Input / Output, abbreviated as I / O), a communication interface, a display unit, and an input device. Among them, the processor, the memory, and the input / output interface are connected through a system bus, and the communication interface, the display unit, and the input device are connected to the system bus through the input / output interface. Among them, the processor of the computer device is used to provide computing and control capabilities. The memory of the computer device includes a non-volatile storage medium and an internal memory. The non-volatile storage medium stores an operating system, a computer program, and a database. The internal memory provides an environment for the operation of the operating system and the computer program in the non-volatile storage medium. The database of the computer device is used to store power grid data. The input / output interface of the computer device is used to exchange information between the processor and external devices. The communication interface of the computer device is used to communicate with external terminals through a network connection. When the computer program is executed by the processor, it implements an evaluation method for the carrying capacity of distributed power sources.

[0175] The display unit of the computer device is used to form a visually visible picture, which can be a display screen, a projection device, or a virtual reality imaging device. The display screen can be a liquid crystal display screen or an electronic ink display screen. The input device of the computer device can be a touch layer covering the display screen, or a button, a trackball, or a touchpad provided on the housing of the computer device, or an external keyboard, touchpad, or mouse, etc.

[0176] Those skilled in the art can understand, Figure 4The structure shown is only a block diagram of some structures related to the solution of this application, and does not constitute a limitation on the computer device to which the solution of this application is applied. The specific computer device may include more or fewer components than those shown in the figure, or combine some components, or have different component arrangements.

[0177] In an exemplary embodiment, a computer device is provided, including a memory and a processor. A computer program is stored in the memory, and when the processor executes the computer program, the following steps are implemented:

[0178] Establish a mathematical model of the output characteristics of distributed power sources; the distributed power sources include a solar thermal power generation system, a photovoltaic power generation system, and a wind power generation system;

[0179] Based on the mathematical model, determine the evaluation indexes of the carrying capacity of distributed power sources; the evaluation indexes include thermal stability, short-circuit current check, voltage deviation check, and harmonic check;

[0180] Connect the distributed power sources to the power grid, and based on the thermal stability of the power grid, determine the reverse load rate in the power grid;

[0181] When at least one of the following situations occurs in the power grid: reverse power transmission of distributed power sources, reverse load rate greater than the preset range, short-circuit current check fails, voltage deviation check fails, or harmonic check fails, the evaluation level of the carrying capacity of distributed power sources is the first level; when the reverse load rate is within the preset range and passes the short-circuit current check, voltage deviation check, and harmonic check, the evaluation level of the carrying capacity of distributed power sources is the second level; when the reverse load rate is less than the preset range and passes the short-circuit current check, voltage deviation check, and harmonic check, the evaluation level of the carrying capacity of distributed power sources is the third level.

[0182] In an embodiment, a computer-readable storage medium is provided, on which a computer program is stored. When the computer program is executed by a processor, the following steps are implemented:

[0183] Establish a mathematical model of the output characteristics of distributed power sources; the distributed power sources include a solar thermal power generation system, a photovoltaic power generation system, and a wind power generation system;

[0184] Based on the mathematical model, determine the evaluation indexes of the carrying capacity of distributed power sources; the evaluation indexes include thermal stability, short-circuit current check, voltage deviation check, and harmonic check;

[0185] Connect the distributed power sources to the power grid, and based on the thermal stability of the power grid, determine the reverse load rate in the power grid;

[0186] When at least one of the following conditions occurs in the power grid: reverse power flow of distributed power sources, reverse load rate greater than the preset range, short-circuit current check fails, voltage deviation check fails, or harmonic check fails, the evaluation level of the distributed power source carrying capacity is the first level; when the reverse load rate is within the preset range and the short-circuit current check, voltage deviation check, and harmonic check are passed, the evaluation level of the distributed power source carrying capacity is the second level; when the reverse load rate is less than the preset range and the short-circuit current check, voltage deviation check, and harmonic check are passed, the evaluation level of the distributed power source carrying capacity is the third level.

[0187] In one embodiment, a computer program product is provided, including a computer program that, when executed by a processor, implements the following steps:

[0188] Establish a mathematical model of the output characteristics of the distributed power source; the distributed power source includes a solar thermal power generation system, a photovoltaic power generation system, and a wind power generation system;

[0189] Based on the mathematical model, determine the evaluation indicators of the distributed power source carrying capacity; the evaluation indicators include thermal stability, short-circuit current check, voltage deviation check, and harmonic check;

[0190] Connect the distributed power source to the power grid, and based on the thermal stability of the power grid, determine the reverse load rate in the power grid;

[0191] When at least one of the following conditions occurs in the power grid: reverse power flow of distributed power sources, reverse load rate greater than the preset range, short-circuit current check fails, voltage deviation check fails, or harmonic check fails, the evaluation level of the distributed power source carrying capacity is the first level; when the reverse load rate is within the preset range and the short-circuit current check, voltage deviation check, and harmonic check are passed, the evaluation level of the distributed power source carrying capacity is the second level; when the reverse load rate is less than the preset range and the short-circuit current check, voltage deviation check, and harmonic check are passed, the evaluation level of the distributed power source carrying capacity is the third level.

[0192] It should be noted that the user information (including but not limited to user equipment information, user personal information, etc.) and data (including but not limited to data for analysis, stored data, displayed data, etc.) involved in this application are all information and data authorized by the user or fully authorized by all parties, and the collection, use, and processing of relevant data need to comply with relevant regulations.

[0193] Those of ordinary skill in the art can understand that all or part of the processes in the methods of the above embodiments can be completed by instructing relevant hardware through a computer program. The computer program can be stored in a non-volatile computer-readable storage medium. When the computer program is executed, it can include the processes of the embodiments of the above methods. Among them, any reference to a memory, database, or other medium used in the embodiments provided in the present application can include at least one of non-volatile memory and volatile memory. Non-volatile memory can include read-only memory (ROM), magnetic tape, floppy disk, flash memory, optical memory, high-density embedded non-volatile memory, resistive random access memory (ReRAM), magnetoresistive random access memory (MRAM), ferroelectric random access memory (FRAM), phase change memory (PCM), graphene memory, etc. Volatile memory can include random access memory (RAM) or external cache memory, etc. By way of illustration and not limitation, RAM can be in various forms, such as static random access memory (SRAM) or dynamic random access memory (DRAM), etc. The databases involved in the embodiments provided in the present application can include at least one of relational databases and non-relational databases. Non-relational databases can include distributed databases based on blockchain, etc., without limitation. The processors involved in the embodiments provided in the present application can be general-purpose processors, central processing units, graphics processing units, digital signal processors, programmable logic devices, data processing logics based on quantum computing, artificial intelligence (AI) processors, etc., without limitation.

[0194] The technical features of the above embodiments can be combined arbitrarily. For the sake of brevity of description, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, it should be considered to be within the scope recorded in the present application.

[0195] The above-described embodiments merely represent several implementation manners of the present application. The description thereof is relatively specific and detailed, but it should not be construed as a limitation to the patent scope of the present application. It should be noted that for those of ordinary skill in the art, without departing from the concept of the present application, several modifications and improvements can still be made, and these all fall within the protection scope of the present application. Therefore, the protection scope of the present application shall be subject to the appended claims.

Claims

1. An evaluation method for the load-bearing capacity of distributed power sources, characterized in that The method includes: Establishing a mathematical model for the output characteristics of distributed power sources; the distributed power sources include solar thermal power generation systems, photovoltaic power generation systems, and wind power generation systems; Based on the mathematical model, determining evaluation indicators for the carrying capacity of distributed power sources; the evaluation indicators include thermal stability, short-circuit current check, voltage deviation check, and harmonic check; Connecting the distributed power sources to the power grid, and determining the reverse load rate in the power grid based on the thermal stability of the power grid; When at least one of the following situations occurs in the power grid: reverse power transmission of distributed power sources, reverse load rate greater than the preset range, short-circuit current check fails, voltage deviation check fails, or harmonic check fails, the evaluation level of the carrying capacity of distributed power sources is the first level; when the reverse load rate is within the preset range and passes the short-circuit current check, voltage deviation check, and harmonic check, the evaluation level of the carrying capacity of distributed power sources is the second level; when the reverse load rate is less than the preset range and passes the short-circuit current check, voltage deviation check, and harmonic check, the evaluation level of the carrying capacity of distributed power sources is the third level.

2. The method according to claim 1, wherein The determining the reverse load rate in the power grid based on the thermal stability of the power grid includes: Determining the power of distributed power sources in the power grid within a preset time period, the power of other power sources except distributed power sources within the preset time period, and the power consumption load of the power grid within the preset time period; Taking the sum of the power of distributed power sources in the power grid within the preset time period and the power of other power sources except distributed power sources within the preset time period as the input power of the power grid within the preset time period; Taking the difference between the input power and the power consumption load as the remaining power of the power grid within the preset time period; Taking the ratio of the remaining power to the actual operation limit value of the power grid as the reverse load rate of the power grid.

3. The method according to claim 1, wherein The evaluation process of the short-circuit current check includes: Before the distributed power sources are connected to the power grid, when the short-circuit current at the peak load of the power grid does not exceed the short-circuit current limit value, the first stage of the short-circuit current check passes; After the distributed power sources are connected to the power grid, determining a first current based on the short-circuit current at the peak load of the power grid, the additional capacity that can be added to the power grid, and the rated voltage of the power grid bus. When the first current is less than the short-circuit current limit value, the second stage of the short-circuit current check passes; When both the first stage of the evaluation and the second stage of the evaluation pass, the evaluation of the short-circuit current check passes.

4. The method according to claim 1, wherein The evaluation process of the voltage deviation check includes: When the positive voltage deviation extreme value in the power grid is less than the positive voltage deviation allowable value and the negative voltage deviation extreme value is greater than the negative voltage deviation allowable value, the evaluation of the voltage deviation check passes.

5. The method according to claim 1, wherein The evaluation process of the harmonic check includes: When the harmonic current in the power grid is less than the harmonic current allowable value and the inter-harmonic voltage content rate is less than the inter-harmonic voltage content rate limit value, the evaluation of the harmonic check passes.

6. The method according to claim 3, characterized in that The calculation formula for the additional capacity that can be added to the power grid includes: ； Among them, is the newly addable capacity in the power grid, is the reverse load rate, is the actual operating limit of the power grid, is the preset margin coefficient.

7. An evaluation device for the load-carrying capacity of distributed power sources, characterized in that, The device includes: A building module, used for establishing a mathematical model for the output characteristics of distributed power sources; the distributed power sources include solar thermal power generation systems, photovoltaic power generation systems, and wind power generation systems; A determination module, configured to determine an evaluation index of the distributed power supply carrying capacity based on the mathematical model; the evaluation index includes thermal stability, short-circuit current verification, voltage deviation verification, and harmonic verification; The determination module is further configured to connect the distributed power supply to the power grid and determine the reverse load rate in the power grid based on the thermal stability of the power grid; An evaluation module, configured to determine that the evaluation level of the distributed power supply carrying capacity is the first level when at least one of the following situations occurs in the power grid: reverse power flow of the distributed power supply, reverse load rate greater than the preset range, short-circuit current verification fails, voltage deviation verification fails, or harmonic verification fails; when the reverse load rate is within the preset range and passes the short-circuit current verification, voltage deviation verification, and harmonic verification, the evaluation level of the distributed power supply carrying capacity is the second level; when the reverse load rate is less than the preset range and passes the short-circuit current verification, voltage deviation verification, and harmonic verification, the evaluation level of the distributed power supply carrying capacity is the third level.

8. A computer device, comprising a memory and a processor, the memory storing a computer program, characterized in that, When the processor executes the computer program, the steps of the method according to any one of claims 1 to 6 are implemented.

9. A computer-readable storage medium, on which a computer program is stored, characterized in that, When the computer program is executed by the processor, the steps of the method according to any one of claims 1 to 6 are implemented.

10. A computer program product, comprising a computer program, characterized in that, When the computer program is executed by the processor, the steps of the method according to any one of claims 1 to 6 are implemented.

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