Method and system for evaluating bearing capacity of distributed power supply of power distribution network

Abstract

The invention discloses a bearing capacity evaluation method and system for a distributed power supply of a power distribution network, and the method comprises the steps: carrying out the deep data analysis of an electrical connection relation in actual production and operation, carrying out the reconstruction of a topological structure related to an equipment subordination relation, and converting the topological structure into a simulation topology suitable for complex calculation and analysis, therefore, the data quality of the bearing capacity assessment method is improved, the assessment accuracy of the bearing capacity assessment method can be further improved, and the method is particularly suitable for power distribution network distributed power supply bearing capacity assessment under high proportion permeation of regional distributed power supplies.

Description

Technical Field

[0001] The present invention relates to the technical field of power system planning, operation and analysis, and in particular to a method and system for evaluating the carrying capacity of distributed power sources in a distribution network. Background Art

[0002] Under the background of "dual carbon", the distribution network faces new challenges of massive distributed energy access and large-scale development of diversified loads. It is necessary to carry out simulation evaluation in a systematic manner, quantify the impact on the distribution network, formulate high-standard planning and high-quality construction implementation plans, and effectively improve the carrying capacity of the distribution network. As an important part of the new power system, the active distribution network plays an important role in the consumption of new energy, especially distributed photovoltaic power generation in the whole county, source-grid-load-storage interaction, and multi-energy complementarity. At the same time, the randomness, intermittency, and undispatchability of the active distribution network have put forward higher requirements for grid planning.

[0003] In the process of evaluating the carrying capacity of distributed power sources in the distribution network, some bottlenecks in data quality and computing performance may be encountered. For example, during the evaluation, the existing current installed capacity statistics of distributed power sources are generally directly retrieved. The statistical data often have the problem of missing or inaccurate original statistical data due to the continuous access of distributed power sources. For example, the equipment affiliation quality under some dedicated lines and dedicated transformers is poor, and the distributed photovoltaic cannot be connected to the corresponding lines and distribution transformers. This will lead to deviations between the analysis results and the actual situation when doing the current installed capacity distribution statistics and carrying capacity evaluation. When performing timing simulation calculation and analysis of complex lines and ultra-long lines, the complexity of the line itself is superimposed on the complexity of the simulation calculation logic. The existing methods often perform simulation calculations of different dimensions for each line in the distribution network, resulting in the simulation calculation analysis taking too long. In addition, some existing evaluation methods often have too single evaluation dimensions, so they cannot accurately and comprehensively reflect the carrying capacity of distributed power sources in the distribution network. Summary of the invention

[0004] In order to solve the problems existing in the prior art, the present invention proposes a method and system for evaluating the carrying capacity of distributed power sources in a distribution network.

[0005] The technical solution of the present invention is as follows:

[0006] A method for evaluating the carrying capacity of a distributed power source in a distribution network, comprising:

[0007] Obtain the topological structure and business operation data of the distribution network in the area to be evaluated;

[0008] Reconstructing the topology structure in relation to device affiliation;

[0009] Divide the carrying capacity of distributed power sources in the distribution network into multiple carrying capacity levels;

[0010] Based on the reconstructed topology structure and business operation data, an assessment is made on whether there is a power reverse transmission phenomenon of distributed power sources, an assessment is made on the bus short-circuit current, voltage deviation and harmonic measured values ​​for each voltage level, and an assessment is made on thermal stability; based on the assessment results on whether there is a power reverse transmission phenomenon of distributed power sources, the assessment results on the bus short-circuit current, voltage deviation and harmonic measured values ​​for each voltage level, and the assessment results on thermal stability, the carrying capacity level and carrying capacity value corresponding to the carrying capacity of the distributed power sources in the distribution network are obtained.

[0011] Furthermore, the specific method for dividing the carrying capacity of the distributed power sources in the distribution network into multiple carrying capacity levels includes: dividing the carrying capacity of the distributed power sources in the distribution network into three carrying capacity levels: a first level for characterizing insufficient absorption of the distributed power sources, a thermal stability alarm of the transformer / line, or a safety risk in the distribution network; a second level for the reverse load of the transformer / line not reaching the warning value or the distributed power source absorption condition is good; and a third level for the transformer / line without reverse load or the distributed power source absorption condition is relatively good.

[0012] Furthermore, based on the reconstructed topology structure and business operation data, the specific methods for evaluating whether there is a power reverse transmission phenomenon of distributed power generation, evaluating the bus short-circuit current, voltage deviation and harmonic measured values ​​for each voltage level, and evaluating the thermal stability include:

[0013] Based on the reconstructed topological structure and business operation data, it is judged whether there is a power reverse transmission phenomenon of the distributed power source through the power flow distribution under several typical operation modes. If there is a power reverse transmission phenomenon in the power flow distribution under any typical operation mode, the carrying capacity of the distributed power source of the distribution network is the first level, and the carrying capacity value of the distributed power source of the distribution network is 0; if there is no power reverse transmission phenomenon in the power flow distribution under any typical operation mode, the voltage levels contained in the distribution network in the area to be evaluated are evaluated as follows to obtain the carrying capacity level and carrying capacity value corresponding to each voltage level:

[0014] According to the order of voltage levels from high to low, the current status and measured harmonic values ​​of the short-circuit current and voltage deviation of each busbar at each voltage level are obtained in turn, and three evaluations are performed corresponding to the short-circuit current verification and evaluation model, the voltage deviation verification and evaluation model, and the harmonic verification and evaluation model. If any of the three evaluations fails, the carrying capacity of the distributed power source of the distribution network is the first level, and the carrying capacity value of the distributed power source of the distribution network at this voltage level is 0; if the three evaluations pass, an evaluation related to the thermal stability model is performed, the reverse power flow of the distribution network at this voltage level is analyzed, and the capacity of the newly added distributed power source is calculated, and the maximum value λmax of the reverse load rate within the evaluation period is statistically calculated. If λmax>80%, the carrying capacity of the distributed power source of the distribution network at this voltage level is the first level, and the carrying capacity value of the distributed power source of the distribution network at this voltage level is 0. The carrying capacity value of the distributed power source of the distribution network is 0; if 0<λmax≤80%, the carrying capacity of the distributed power source of the distribution network under this voltage level is the second level; if λmax≤0, the carrying capacity of the distributed power source of the distribution network under this voltage level is the third level; at the same time, for the second level and the third level, based on the calculated capacity of the newly added distributed power source, two evaluations related to the short-circuit current verification and evaluation model and the voltage deviation verification and evaluation model are performed; if any of the two evaluations fails, the capacity of the newly added distributed power source is reduced, and two evaluations related to the short-circuit current verification and evaluation model and the voltage deviation verification and evaluation model are performed again until the two evaluations are passed; the capacity of the newly added distributed power source corresponding to the two evaluations is used as the carrying capacity value of the distributed power source of the distribution network under this voltage level.

[0015] Furthermore, the expression of the thermal stability evaluation model is:

[0016]

[0017] Wherein, PD(t) is the output of distributed generation within the power supply range of the transformer or line in period t, kW; PC(t) is the output of other power sources other than distributed generation in period t, kW; PL(t) is the power load of the system in period t, kW; PNet(t) is the grid power of the transformer or line in period t, kW; Se is the actual operating limit of the transformer or line, kW.

[0018] Furthermore, the expression of the short-circuit current verification evaluation model is:

[0019]

[0020] In the formula, I xz is the current value of busbar short-circuit current under system peak load operation mode, A; U N is the rated voltage of the busbar at different voltage levels, kV; I mis the short-circuit current limit allowed by the system, A.

[0021] Furthermore, the voltage deviation calibration evaluation model is expressed as:

[0022]

[0023] Where, ΔP is the active power increment injected after the distributed generation is connected to the system, kW; ΔQ is the corresponding reactive power increment, kVar; RL is the resistance value of the grid, Ω; XL is the reactance value of the grid, Ω;

[0024]

[0025] Where δU+ and δU- are the positive and negative voltage deviation extremes calculated based on the formula, kV.

[0026] Furthermore, the expression of the harmonic verification evaluation model is:

[0027] I xz,r <I r

[0028] In the formula, I xz,r is the measured value of the rth harmonic current of the power grid node, A; I r is the allowable value of the rth harmonic current injected into the grid nodes of each voltage level, A;

[0029] IHRU xz,r <IIHRU r

[0030] Where, IHRUxz,r is the measured value of the rth harmonic voltage content rate at the grid node, %; IIHRUr is the limit value of the rth harmonic voltage content rate at each voltage level, %.

[0031] A load-bearing capacity evaluation system for distributed power sources in a distribution network, comprising a data acquisition module, a topology reconstruction module, a load-bearing capacity classification module and an evaluation module;

[0032] The data acquisition module is used to acquire the topological structure and business operation data of the distribution network in the area to be evaluated;

[0033] The topology reconstruction module is used to reconstruct the topology structure in relation to the device affiliation;

[0034] The said load capacity level classification module is used to classify the load capacity of the distributed power source of the distribution network into multiple load capacity levels;

[0035] The evaluation module is used to evaluate whether there is a power reverse transmission phenomenon of distributed power sources, evaluate the bus short-circuit current, voltage deviation and harmonic measured values ​​at each voltage level, and evaluate the thermal stability based on the reconstructed topology structure and business operation data; according to the evaluation results of whether there is a power reverse transmission phenomenon of distributed power sources, the evaluation results of the bus short-circuit current, voltage deviation and harmonic measured values ​​at each voltage level, and the evaluation results related to thermal stability, obtain the carrying capacity level and carrying capacity value corresponding to the carrying capacity of the distributed power sources in the distribution network.

[0036] An electronic device comprises a memory and a processor, wherein the memory stores a computer program, and the processor is used to call and run the computer program stored in the memory to execute any of the methods described above.

[0037] A computer-readable storage medium stores a computer program, wherein the computer program implements the steps of any of the above methods when executed by a processor.

[0038] Compared with the prior art, the present invention has the following beneficial effects:

[0039] The present invention proposes a method and system for evaluating the carrying capacity of distributed power sources in a distribution network. The method reconstructs the topological structure related to the device subordination relationship through in-depth data analysis of the electrical connection relationship in actual production operation, which can be converted into a simulation topology suitable for complex calculation and analysis, thereby improving the data quality of the carrying capacity evaluation method, thereby further improving the evaluation accuracy of the carrying capacity evaluation method, and is particularly suitable for the evaluation of the carrying capacity of distributed power sources in distribution networks with a high proportion of regional distributed power sources.

[0040] The carrying capacity evaluation method of the present invention performs a multi-dimensional evaluation, including an evaluation of whether there is a power reverse transmission phenomenon of distributed power sources, an evaluation of the bus short-circuit current, voltage deviation and harmonic measured values ​​at each voltage level, and an evaluation of thermal stability, so that a more comprehensive and accurate evaluation result can be obtained.

[0041] The carrying capacity evaluation method of the present invention designs a multi-dimensional evaluation logic, and now evaluates whether there is a distributed power supply power backflow phenomenon based on the reconstructed topological structure and business operation data. Based on the evaluation results, the bus short-circuit current, voltage deviation and harmonic measured values ​​are evaluated at each voltage level and the thermal stability is evaluated. For the distribution network that does not pass the evaluation of the distributed power supply power backflow phenomenon, no subsequent evaluation is performed, which saves computing costs and increases computing efficiency. At the same time, the evaluation at each voltage level makes the acquired carrying capacity more accurate. BRIEF DESCRIPTION OF THE DRAWINGS

[0042] Figure 1 Flow chart of the method for evaluating the carrying capacity of distributed power sources in a distribution network in an embodiment. DETAILED DESCRIPTION

[0043] The present invention is further explained below in conjunction with the accompanying drawings and specific embodiments. It should be understood that these embodiments are only used to illustrate the present invention and are not used to limit the scope of the present invention. After reading the present invention, various equivalent modifications of the present invention by those skilled in the art all fall within the scope defined by the claims attached to this application.

[0044] Embodiment 1:

[0045] A method for evaluating the carrying capacity of a distributed power source in a distribution network of the present invention is as follows: Figure 1 As shown, including:

[0046] S1. Obtain the topological structure and business operation data of the distribution network in the area to be evaluated;

[0047] S2, reconstructing the topology structure in relation to the device affiliation;

[0048] S3, dividing the carrying capacity of the distributed power sources of the distribution network into multiple carrying capacity levels;

[0049] S4. Based on the reconstructed topology and business operation data, evaluate whether there is a phenomenon of power reverse transmission of distributed power sources, evaluate the actual measured values ​​of bus short-circuit current, voltage deviation and harmonics for each voltage level, and evaluate the thermal stability; based on the evaluation results of whether there is a phenomenon of power reverse transmission of distributed power sources, the evaluation results of actual measured values ​​of bus short-circuit current, voltage deviation and harmonics for each voltage level, and the evaluation results of thermal stability, obtain the carrying capacity level and carrying capacity value corresponding to the carrying capacity of the distributed power sources in the distribution network.

[0050] Furthermore, the business operation data includes five types of data: grid relationship data, equipment file data, operation curve data, calculation parameter data, and simulation result data. Among them, grid relationship data, which stores data such as the electrical connection relationship between power grid equipment and the start status of switches, is the basic skeleton for topology reconstruction; equipment archive data, which stores basic information of power grid equipment such as substations, lines, overhead sections, cable sections, in-station connecting lines, busbars, circuit breakers, load switches, disconnectors, main transformers, distribution transformers, distributed power sources, electric vehicle charging piles, energy storage, etc., including equipment name, voltage level, equipment capacity, operating status, etc.; operation curve data, which refers to substation load curves, line load curves, distribution transformer load curves, distributed photovoltaic output curves, electric vehicle charging pile load curves, energy storage charging and discharging curves, etc., can be obtained in real time from the measurement center of the data platform by selecting a time range, and can be adjusted as needed; calculation parameter data, including historical example parameter configuration, example default parameter configuration, distributed photovoltaic typical output curve, electric vehicle charging pile typical load curve, energy storage typical charging and discharging curve, etc.; simulation result data, including branch flow, branch loss, node voltage, short-circuit current, and node carrying capacity.

[0051] Furthermore, a topology mapping model may be constructed based on the above business operation data, as follows:

[0052] Example model:

[0053] P 算例 =m model_id +P model_type +P width +P height +P angle +P width_ratio +P height_ratio +P x_axis

[0054] +P y_axis

[0055] Where P model_id Represents the model ID, P model_type Represents the model type, P width Represents the width of the graphic, P height Represents the height of the graph, P angle Represents the angle of the figure, P width_ratio Represents the width magnification ratio, P height_ratio Represents the height magnification ratio, P x_axis represents the x-axis coordinate, P y_axis Represents the y-axis coordinate.

[0056] Topological connection model:

[0057] U 拓扑=U diagram_id +U start_model_id +U start_port_id +U start_model_type +U end_model_id

[0058] +U end_port_id +U end_model_type

[0059] Where U diagram_id Represents the case ID, U start_model_id Represents the starting model ID, U start_port_id Represents the starting port ID, U start_model_type Represents the starting model type, U end_model_id Represents the endpoint model ID, U end_port_id Represents the endpoint port ID, U end_model_type Represents the endpoint model type.

[0060] Distribution transformer load curve model:

[0061] L 配变负荷 =L model_id +L load_name +L basekv +L conn_method +L active_power +L reactive_power

[0062] +L power_factor +L vminpu +L vmaxpu

[0063] Where, L model_id Represents the model ID, L load_name Represents the name of the distribution transformer, L basekv Represents voltage level (kV), L conn_method Represents the connection mode, L active_power Represents active power (kW), L reactive_power Represents reactive power (kVar), L power_factor Represents the power factor, L vminpu Represents the voltage per unit value (minimum), L vmaxpu Represents the voltage per unit value (maximum).

[0064] Photovoltaic output curve model:

[0065] L 光伏出力 =L model_id +L output_name +L basekv +L conn_method +L active_power +L reactive_power

[0066] +L power_factor+L vminpu +L vmaxpu

[0067] Where, L model_id Represents the model ID, L output_name Represents the name of the distribution transformer, L basekv Represents voltage level (kV), L conn_method Represents the connection mode, L active_power Represents active power (kW), L reactive_power Represents reactive power (kVar), L power_factor Represents the power factor, L vminpu Represents the voltage per unit value (minimum), L vmaxpu Represents the voltage per unit value (maximum).

[0068] Branch flow result model:

[0069] U 支路潮流 =U code +U msg +U modelId +U modelType +U modelName +U hour +U modelName

[0070] +U activePower +U reactivePower

[0071] Where U code Represents the message status code, U msg Represents the message content, U modelId Represents component ID, U modelType Represents the device type, U modelName Represents the component name, U hour Represents time, U modelName Represents the component name, U activePower Represents merit, U reactivePower Represents reactive power.

[0072] Branch loss result model:

[0073] U 支路损耗 =U code +U msg +U modelId +U modelType +U modelName +U connLineType +U startId +U start +U endId +U end +U hour +U activePower +U reactivePower +Up1 +U q1 +U p2 +U q2 +U p3 +U q3 +U forwardLoadRate +U reverseLoadRate

[0074] Where U code Represents the message status code, U msg Represents the message content, U modelId Represents the component ID, U modelType Represents the device type, U modelName Represents the component name, U connLineType Represents the connection type, U startId Represents the headend ID, U start Represents the head end, U endId Represents the terminal ID, U end Represents the end, U hour Represents time, U activePower Represents merit, U reactivePower Represents work, U p1 A represents active power, U q1 A represents reactive power, U p2 represents the active power of B, U q2 Represents B reactive power, U p3 represents C active power, U q3 Represents C reactive power, U forwardLoadRate Represents the forward load rate, U reverseLoadRate Represents the reverse load ratio.

[0075] Node voltage result model (line voltage):

[0076] U 节点电压(线电压)

[0077] =U code +U msg +U total +U modelId +U modelType +U modelName +U hour

[0078] +U basekv +U uab +U ubc +U uac

[0079] Where U code Represents the message status code, U msg Represents the message content, U total Represents list data, U modelId Represents the device id, U modelTypeRepresents the device type, U modelName Represents the device name, U hour represents the time point, U basekv Represents the reference voltage, U uab represents the line voltage (ab), U ubc represents the line voltage (bc), U uac Represents the line voltage (ac).

[0080] Node voltage result model (phase voltage):

[0081] U 节点电压(相电压)

[0082] =U code +U msg +U total +U modelId +U modelType +U modelName +U hour

[0083] +U basekv +U vAngle1 +U v1 +U vAngle2 +U v2 +U vAngle3 +U v3

[0084] Where U code Represents the message status code, U msg Represents the message content, U total Represents list data, U modelId Represents the device id, U modelType Represents the device type, U modelName Represents the device name, U hour represents the time point, U basekv Represents the reference voltage, U vAngle1 represents the phase angle of phase A, U v1 Represents phase A voltage (kV), U vAngle2 represents the phase angle of phase B, U v2 represents the B phase voltage (kV), U vAngle3 represents the phase angle of phase C, U v3 Represents the C phase voltage (kV).

[0085] Short-circuit current result model:

[0086] A 短路电流 =A code +A msg +A total +A modelId +A modelType +A modelName +A voltageLevel

[0087] +A threePhase +A modelName +A singlePhase +A ll

[0088] In the formula, A code Represents the message status code, A msg Represents the message content, A total Represents list data, A modelId Represents the component ID, A modelType Represents the device type, A modelName Represents the component name, A voltageLevel Represents the voltage level, A threePhase Represents the three-phase short-circuit current, A modelName Represents the component name, A singlePhase Represents the single-phase ground short-circuit current, A ll Represents the short-circuit current between two phases. Based on the topology mapping model, a distributed power supply carrying capacity simulation index model is established.

[0089] Embodiment 2:

[0090] This embodiment is further designed on the basis of the first embodiment in that the specific method of dividing the carrying capacity of the distributed power source of the distribution network into multiple carrying capacity levels in this embodiment includes: dividing the carrying capacity of the distributed power source of the distribution network into three carrying capacity levels: a first level for characterizing insufficient distributed power source absorption, transformer / line thermal stability alarm or safety risk of the distribution network, a second level for the transformer / line reverse load not reaching the warning value or the distributed power source absorption condition is good, and a third level for the transformer / line without reverse load or the distributed power source absorption condition is relatively good.

[0091] Embodiment three:

[0092] This embodiment is further designed on the basis of the second embodiment in that, in this embodiment, based on the reconstructed topology structure and business operation data, the specific method for evaluating whether there is a distributed power supply power reverse transmission phenomenon, evaluating the bus short-circuit current, voltage deviation and harmonic measured values ​​at each voltage level, and evaluating the thermal stability includes:

[0093] Clarify the scope of the distribution network in the area to be evaluated and the topological structure after reconstruction. Usually, the evaluation scope is divided into the power supply area of ​​a single 220kV transformer, and the evaluation objects include all 35~220kV transformers, 35~110kV lines, and 10~220kV busbars in the area.

[0094] Based on the reconstructed topological structure and business operation data, the flow distribution under several typical operation modes is used to determine whether there is a power reverse transmission phenomenon of the distributed power source. If there is a power reverse transmission phenomenon under any typical operation mode, the carrying capacity of the distributed power source of the distribution network is the first level, and the carrying capacity value of the distributed power source of the distribution network is 0; if there is no power reverse transmission phenomenon under any typical operation mode, the voltage level contained in the distribution network in the area to be evaluated is evaluated as follows to obtain the carrying capacity level and carrying capacity value corresponding to each voltage level:

[0095] According to the order of voltage levels from high to low, the current status and measured harmonic values ​​of the short-circuit current and voltage deviation of each busbar at each voltage level are obtained in turn, and three evaluations are performed corresponding to the short-circuit current verification and evaluation model, the voltage deviation verification and evaluation model, and the harmonic verification and evaluation model. If any of the three evaluations fails, the carrying capacity of the distributed power source of the distribution network is the first level, and the carrying capacity value of the distributed power source of the distribution network at this voltage level is 0; if the three evaluations pass, an evaluation related to the thermal stability model is performed, the reverse power flow of the distribution network at this voltage level is analyzed, and the capacity of the newly added distributed power source is calculated, and the maximum value λmax of the reverse load rate within the evaluation period is statistically calculated. If λmax>80%, the carrying capacity of the distributed power source of the distribution network at this voltage level is the first level, and the carrying capacity value of the distributed power source of the distribution network at this voltage level is 0. The carrying capacity value of the distributed power source of the distribution network is 0; if 0<λmax≤80%, the carrying capacity of the distributed power source of the distribution network under this voltage level is the second level; if λmax≤0, the carrying capacity of the distributed power source of the distribution network under this voltage level is the third level; at the same time, for the second level and the third level, based on the calculated capacity of the newly added distributed power source, two evaluations related to the short-circuit current verification and evaluation model and the voltage deviation verification and evaluation model are performed; if any of the two evaluations fails, the capacity of the newly added distributed power source is reduced, and two evaluations related to the short-circuit current verification and evaluation model and the voltage deviation verification and evaluation model are performed again until the two evaluations are passed; the capacity of the newly added distributed power source corresponding to the two evaluations is used as the carrying capacity value of the distributed power source of the distribution network under this voltage level.

[0096] Embodiment 4:

[0097] This embodiment is further designed on the basis of the third embodiment in that the thermal stability assessment in this embodiment is based on the historical load sequence of the transformer and the line, and the thermal stability of the transformer or the line does not exceed the limit, and the newly added capacity margin of the distributed power source is assessed. The expression of the thermal stability assessment model, that is, the calculation formula of the reverse load rate λ(t) of the transformer and the line in the t period is:

[0098]

[0099] Where PD(t) is the output of the distributed generation within the power supply range of the transformer or line in period t, kW; PC(t) is the output of other power sources other than the distributed generation in period t, kW; PL(t) is the power load of the system in period t, kW; PNet(t) is the grid power of the transformer or line in period t, kW; Se is the actual operating limit of the transformer or line, kW. The time resolution t is set to 15 minutes.

[0100] Embodiment five:

[0101] This embodiment is further designed on the basis of the fourth embodiment in that the short-circuit current verification and evaluation in this embodiment is based on the principle that the short-circuit current of the busbars of different voltage levels of the system does not exceed the limit before and after the distributed power source is connected to the system. Before the distributed power source is connected to the system, in the three evaluations, the short-circuit current verification and evaluation model is:

[0102] I xz <I m

[0103] Assuming that the distributed power supply system with a capacity of Pm is connected, the expression of the short-circuit current verification evaluation model in the two evaluations is:

[0104]

[0105] In the formula, I xz It is the current value of bus short-circuit current under system peak load operation mode, which can be set according to the short-circuit capacity under bus high load mode, A; U N is the rated voltage of the busbar at different voltage levels, kV; I m For the short-circuit current limit allowed by the system, the present invention selects the smaller value of the breaking current limit of the circuit breaker connected to the busbar, A. During the three evaluations, the capacity is Pm=0, so the conversion of the two models can also be performed.

[0106] Embodiment six:

[0107] This embodiment is further designed on the basis of the fifth embodiment in that the voltage deviation verification and evaluation in this embodiment is based on the principle that the voltages of different voltage levels of the system do not exceed the limit before and after the distributed power source is connected to the system. Assuming that the distributed power source with a capacity of Pm is connected and causes bus voltage deviations of different voltage levels, the expression of the voltage deviation verification and evaluation model is:

[0108]

[0109] Where, ΔP is the active power increment injected after the distributed generation is connected to the system, kW; ΔQ is the corresponding reactive power increment, kVar; RL is the resistance value of the grid, Ω; XL is the reactance value of the grid, Ω;

[0110] Based on the voltage sequence of each busbar during the assessment period and the voltage deviation limit specified in the relevant standards, the allowable positive and negative voltage deviations ΔU+ and ΔU- caused by the access of distributed generation are estimated and verified according to the following formula:

[0111]

[0112] Where δU+ and δU- are the positive and negative voltage deviation extremes calculated based on the formula, kV.

[0113] Embodiment seven:

[0114] This embodiment is further designed on the basis of the sixth embodiment. In this embodiment, the harmonic verification is based on the principle that the harmonic current value and harmonic voltage content of the distributed power source connected to the grid node in the system do not exceed the limit. The verification object includes all nodes that may be affected by the harmonic current and interharmonic voltage provided by the distributed power source. The expression of the harmonic verification evaluation model is

[0115] I xz,r <I r

[0116] In the formula, I xz,r is the measured value of the rth harmonic current of the power grid node, A; I r The permissible value of the rth harmonic current injected into the grid nodes of each voltage level can be selected in combination with the corresponding standards, A;

[0117] The interharmonic voltage content rate is checked according to the following formula:

[0118] IHRU xz,r <IIHRU r

[0119] Where, IHRUxz,r is the measured value of the rth harmonic voltage content rate at the grid node, %; IIHRUr is the limit value of the rth harmonic voltage content rate at each voltage level, which can be selected in combination with the corresponding standards, %.

[0120] Embodiment eight:

[0121] A load-bearing capacity evaluation system for a distributed power source in a power distribution network of the present invention comprises a data acquisition module, a topology reconstruction module, a load-bearing capacity classification module and an evaluation module;

[0122] A data acquisition module is used to obtain the topological structure and business operation data of the distribution network in the area to be evaluated;

[0123] A topology reconstruction module is used to reconstruct the topology structure in relation to the device affiliation;

[0124] The said load capacity level classification module is used to classify the load capacity of the distributed power source of the distribution network into multiple load capacity levels;

[0125] The evaluation module is used to evaluate whether there is a power reverse transmission phenomenon of distributed power sources, evaluate the actual measured values ​​of bus short-circuit current, voltage deviation and harmonics at each voltage level, and evaluate the thermal stability based on the reconstructed topological structure and business operation data; according to the evaluation results of whether there is a power reverse transmission phenomenon of distributed power sources, the evaluation results of the actual measured values ​​of bus short-circuit current, voltage deviation and harmonics at each voltage level, and the evaluation results of thermal stability, the carrying capacity level and carrying capacity value corresponding to the carrying capacity of the distributed power sources in the distribution network are obtained.

[0126] Embodiment nine:

[0127] An electronic device comprises a memory and a processor, wherein the memory stores a computer program, and the processor is used to call and run the computer program stored in the memory to execute any of the methods described above.

[0128] A computer-readable storage medium stores a computer program, and when the computer program is executed by a processor, the steps of any of the above methods are implemented.

[0129] The above description is only a specific implementation of the present invention, but the protection scope of the present invention is not limited thereto. Any changes or substitutions that can be easily conceived by a technician familiar with the technical field within the technical scope disclosed by the present invention should be covered by the protection scope of the present invention.

Claims

1. A method for evaluating the carrying capacity of distributed power sources in a distribution network, characterized in that: include: Obtain the topological structure and business operation data of the distribution network in the area to be evaluated; Reconstructing the topology structure in relation to device affiliation; Divide the carrying capacity of distributed power sources in the distribution network into multiple carrying capacity levels; Based on the reconstructed topology structure and business operation data, an assessment is made on whether there is a power reverse transmission phenomenon of distributed power sources, an assessment is made on the bus short-circuit current, voltage deviation and harmonic measured values ​​for each voltage level, and an assessment is made on thermal stability; based on the assessment results on whether there is a power reverse transmission phenomenon of distributed power sources, the assessment results on the bus short-circuit current, voltage deviation and harmonic measured values ​​for each voltage level, and the assessment results on thermal stability, the carrying capacity level and carrying capacity value corresponding to the carrying capacity of the distributed power sources in the distribution network are obtained.

2. The method for evaluating the carrying capacity of distributed power sources in a distribution network according to claim 1, characterized in that: The specific method for dividing the carrying capacity of the distributed power sources in the distribution network into multiple carrying capacity levels includes: dividing the carrying capacity of the distributed power sources in the distribution network into three carrying capacity levels: a first level for characterizing insufficient absorption of the distributed power sources, a thermal stability alarm of the transformer / line, or a safety risk in the distribution network; a second level for the reverse load of the transformer / line not reaching the warning value or the distributed power source absorption condition is good; and a third level for the transformer / line without reverse load or the distributed power source absorption condition is relatively good.

3. The method for evaluating the carrying capacity of distributed power sources in a distribution network according to claim 2, characterized in that: Based on the reconstructed topology and business operation data, the specific methods for evaluating whether there is a power reverse transmission phenomenon of distributed power generation, evaluating the bus short-circuit current, voltage deviation and harmonic measured values ​​for each voltage level, and evaluating the thermal stability include: Based on the reconstructed topological structure and business operation data, it is judged whether there is a power reverse transmission phenomenon of the distributed power source through the power flow distribution under several typical operation modes. If there is a power reverse transmission phenomenon in the power flow distribution under any typical operation mode, the carrying capacity of the distributed power source of the distribution network is the first level, and the carrying capacity value of the distributed power source of the distribution network is 0; if there is no power reverse transmission phenomenon in the power flow distribution under any typical operation mode, the voltage levels contained in the distribution network in the area to be evaluated are evaluated as follows to obtain the carrying capacity level and carrying capacity value corresponding to each voltage level: According to the order of voltage levels from high to low, the current status and measured harmonic values ​​of the short-circuit current and voltage deviation of each busbar at each voltage level are obtained in turn, and three evaluations are performed corresponding to the short-circuit current verification and evaluation model, the voltage deviation verification and evaluation model, and the harmonic verification and evaluation model. If any of the three evaluations fails, the carrying capacity of the distributed power source of the distribution network is the first level, and the carrying capacity value of the distributed power source of the distribution network at this voltage level is 0; if the three evaluations pass, an evaluation related to the thermal stability model is performed, the reverse power flow of the distribution network at this voltage level is analyzed, and the capacity of the newly added distributed power source is calculated, and the maximum value λmax of the reverse load rate within the evaluation period is statistically calculated. If λmax>80%, the carrying capacity of the distributed power source of the distribution network at this voltage level is the first level, and the carrying capacity value of the distributed power source of the distribution network at this voltage level is 0. The carrying capacity value of the distributed power source of the distribution network is 0; if 0<λmax≤80%, the carrying capacity of the distributed power source of the distribution network under this voltage level is the second level; if λmax≤0, the carrying capacity of the distributed power source of the distribution network under this voltage level is the third level; at the same time, for the second level and the third level, based on the calculated capacity of the newly added distributed power source, two evaluations related to the short-circuit current verification and evaluation model and the voltage deviation verification and evaluation model are performed; if any of the two evaluations fails, the capacity of the newly added distributed power source is reduced, and two evaluations related to the short-circuit current verification and evaluation model and the voltage deviation verification and evaluation model are performed again until the two evaluations are passed; the capacity of the newly added distributed power source corresponding to the two evaluations is used as the carrying capacity value of the distributed power source of the distribution network under this voltage level.

4. The method for evaluating the carrying capacity of distributed power sources in a distribution network according to claim 3, characterized in that: The expression of the thermal stability evaluation model is: Wherein, PD(t) is the output of distributed generation within the power supply range of the transformer or line in period t, kW; PC(t) is the output of other power sources other than distributed generation in period t, kW; PL(t) is the power load of the system in period t, kW; PNet(t) is the grid power of the transformer or line in period t, kW; Se is the actual operating limit of the transformer or line, kW.

5. The method for evaluating the carrying capacity of distributed power sources in a distribution network according to claim 4, characterized in that: The expression of the short-circuit current verification evaluation model is: In the formula, I xz is the current value of busbar short-circuit current under system peak load operation mode, A; U N is the rated voltage of the busbar at different voltage levels, kV; I m is the short-circuit current limit allowed by the system, A.

6. The method for evaluating the carrying capacity of distributed power sources in a distribution network according to claim 5, characterized in that: The expression of the voltage deviation verification evaluation model is: Where, ΔP is the active power increment injected after the distributed generation is connected to the system, kW; ΔQ is the corresponding reactive power increment, kVar; RL is the resistance value of the grid, Ω; XL is the reactance value of the power grid, Ω; Where δU+ and δU- are the positive and negative voltage deviation extremes calculated based on the formula, kV.

7. The method for evaluating the carrying capacity of distributed power sources in a distribution network according to claim 6, characterized in that: The expression of the harmonic verification evaluation model is: I xz,r <I r In the formula, I xz,r is the measured value of the rth harmonic current of the power grid node, A; I r is the allowable value of the rth harmonic current injected into the grid nodes of each voltage level, A; THIRD xz,r <IIHRU r Where, IHRUxz,r is the measured value of the rth harmonic voltage content rate at the grid node, %; IIHRUr is the limit value of the rth harmonic voltage content rate at each voltage level, %.

8. A system for evaluating the carrying capacity of distributed power sources in a distribution network, characterized in that: It includes data acquisition module, topology reconstruction module, carrying capacity classification module and evaluation module; The data acquisition module is used to acquire the topological structure and business operation data of the distribution network in the area to be evaluated; The topology reconstruction module is used to reconstruct the topology structure in relation to the device affiliation; The said load capacity level classification module is used to classify the load capacity of the distributed power source of the distribution network into multiple load capacity levels; The evaluation module is used to evaluate whether there is a power reverse transmission phenomenon of distributed power sources, evaluate the bus short-circuit current, voltage deviation and harmonic measured values ​​at each voltage level, and evaluate the thermal stability based on the reconstructed topology structure and business operation data; according to the evaluation results of whether there is a power reverse transmission phenomenon of distributed power sources, the evaluation results of the bus short-circuit current, voltage deviation and harmonic measured values ​​at each voltage level, and the evaluation results related to thermal stability, obtain the carrying capacity level and carrying capacity value corresponding to the carrying capacity of the distributed power sources in the distribution network.

9. An electronic device, characterized in that: The electronic device comprises a memory and a processor, wherein the memory stores a computer program, and the processor is configured to call and run the computer program stored in the memory to execute the method according to any one of claims 1 to 7.

10. A computer-readable storage medium storing a computer program, characterized in that: When the computer program is executed by a processor, the steps of the method as claimed in any one of claims 1 to 7 are implemented.

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