A grid-connected detection method, device, medium and product of an AC-DC power distribution system

Abstract

The application discloses a kind of grid-connected detection method, equipment, medium and product of AC-DC distribution system, the method includes: establishing the power flow model of AC-DC distribution system before distributed power grid connection, and according to power flow model obtains time series power flow result, the reliability calculation of AC-DC distribution system is carried out, obtains reliability calculation index, according to time series power flow result and reliability calculation index, the comprehensive performance index of AC-DC distribution system is constructed, according to comprehensive performance index, the operation state information of AC-DC distribution system is generated for distributed power grid connection.According to operation state information, the weak link that AC-DC distribution system needs to be reformed can be determined, and technical support and guidance can be provided for distributed power grid connection strategy, which is conducive to promoting the safe and reliable operation of AC-DC distribution system.Through optimization scheduling and power supply planning, the operation efficiency of AC-DC distribution system can be improved, the operation cost is reduced, and the accuracy of grid-connected detection of AC-DC distribution system is improved.

Description

TECHNICAL FIELD

[0001] The embodiment of the present application relates to the technical field of power grid detection, and particularly relates to a grid-connection detection method, device, medium and product of an AC / DC power distribution system. BACKGROUND

[0002] With the innovative development of grid-connection of distributed power supply and other technologies, the traditional AC power distribution network is gradually replaced by the AC / DC power distribution system containing a large number of distributed power supplies, and the AC / DC power distribution system has obvious advantages in power supply quality, energy loss and safety and stability. The AC / DC power distribution system is usually composed of an AC power grid, a DC power grid, a converter station, photovoltaic and wind turbine distributed power supplies, and the converter and the distributed power supply contain complex control strategies and operation modes, which increase the difficulty of steady-state and transient-state analysis. At the same time, the grid-connection of the distributed power supply and the DC power grid may change the power flow direction and distribution, which increases the complexity of risk assessment and reliability calculation of the AC / DC power distribution system. Therefore, it is necessary to comprehensively evaluate the safety and stability, power quality, reliability and economy of the AC / DC power distribution system, and provide guidance and suggestions for the grid-connection strategy and construction scheme of the distributed power supply.

[0003] Due to the fact that the AC / DC power distribution system contains a large number of power electronic devices, control and protection equipment and controllable loads, the modeling, simulation analysis and optimal operation control of the AC / DC power distribution system are more challenging. At present, the traditional grid-connection detection method of the AC / DC power distribution system containing distributed power supplies acquires real-time data such as voltage and current after the grid-connection of the distributed power supply through measurement data, and then establishes an evaluation index system and a model to qualitatively evaluate the current power quality of the AC / DC power distribution system. However, this method cannot give guidance on the position and strategy before the grid-connection of the distributed power supply, and mainly focuses on the influence of the distributed power supply on the AC power distribution network, ignoring the influence of the voltage source converter station and the DC power grid, so that the accuracy of the grid-connection detection of the AC / DC power distribution system is low. SUMMARY

[0004] The present application provides a grid-connection detection method, device, medium and product of an AC / DC power distribution system to improve the accuracy of the grid-connection detection of the AC / DC power distribution system.

[0005] In a first aspect, the embodiment of the present application provides a grid-connection detection method of an AC / DC power distribution system, and the method comprises:

[0006] establishing a power flow model of the AC / DC power distribution system before the grid-connection of the distributed power supply, and obtaining time-series power flow results according to the power flow model;

[0007] performing reliability calculation on the AC / DC power distribution system to obtain reliability calculation indexes;

[0008] construct a comprehensive performance index of the AC-DC power distribution system according to the time sequence power flow result and the reliability calculation index;

[0009] generate operation state information of the AC-DC power distribution system in the distributed power source grid connection according to the comprehensive performance index.

[0010] In a second aspect, the embodiment of the present application further provides a grid connection detection device of an AC-DC power distribution system, and the device comprises:

[0011] a time sequence power flow result acquisition module, configured to establish a power flow model of the AC-DC power distribution system before grid connection of a distributed power source, and obtain a time sequence power flow result according to the power flow model;

[0012] a reliability calculation index acquisition module, configured to perform reliability calculation on the AC-DC power distribution system, and obtain a reliability calculation index;

[0013] a comprehensive performance index calculation module, configured to construct a comprehensive performance index of the AC-DC power distribution system according to the time sequence power flow result and the reliability calculation index;

[0014] an operation state information generation module, configured to generate operation state information of the AC-DC power distribution system in the distributed power source grid connection according to the comprehensive performance index.

[0015] In a third aspect, the embodiment of the present application further provides a computer device, and the computer device comprises:

[0016] one or more processors;

[0017] a storage device, configured to store one or more programs;

[0018] when the one or more programs are executed by the one or more processors, the one or more processors implement the grid connection detection method of the AC-DC power distribution system provided in the first aspect of the present application.

[0019] In a fourth aspect, the embodiment of the present application further provides a computer readable storage medium, and the computer readable storage medium stores a computer program, and the program is executed by a processor to implement the grid connection detection method of the AC-DC power distribution system provided in the first aspect of the present application.

[0020] In a fifth aspect, the embodiment of the present application further provides a computer program product, and the computer program product comprises a computer program, and the computer program is executed by a processor to implement the grid connection detection method of the AC-DC power distribution system provided in the first aspect of the present application.

[0021] In the embodiment, a power flow model of the AC-DC power distribution system before the distributed power source is connected to the grid is established, and time sequence power flow results are obtained according to the power flow model. The reliability of the AC-DC power distribution system is calculated to obtain reliability calculation indexes. The comprehensive performance indexes of the AC-DC power distribution system are constructed according to the time sequence power flow results and the reliability calculation indexes. The operation state information of the AC-DC power distribution system for connecting the distributed power source to the grid is generated according to the comprehensive performance indexes. According to the operation state information, the weak links that need to be improved of the AC-DC power distribution system can be determined, and technical support and guidance can be provided for the distributed power source connection strategy, which is conducive to promoting the safe and reliable operation of the AC-DC power distribution system. Through optimal scheduling and power source planning, the operation efficiency of the AC-DC power distribution system can be improved, the operation cost can be reduced, and the accuracy of the grid connection detection of the AC-DC power distribution system can be improved. BRIEF DESCRIPTION OF DRAWINGS

[0022] Figure 1 is a flow chart of a grid connection detection method of an AC-DC power distribution system according to an embodiment of the present application;

[0023] Figure 2 is a schematic diagram of a DC power distribution network topology according to an embodiment of the present application;

[0024] Figure 3 is a schematic diagram of a topology structure of an AC-DC power distribution system according to an embodiment of the present application;

[0025] Figure 4 is a structural example diagram of a grid connection detection device of an AC-DC power distribution system according to an embodiment of the present application;

[0026] Figure 5 is a schematic diagram of a computer device according to an embodiment of the present application. DETAILED DESCRIPTION

[0027] In order for those skilled in the art to better understand the present application, the technical solutions in the embodiments of the present application will be described clearly and completely below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only a part of the embodiments of the present application, not all. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor should be within the scope of protection of the present application.

[0028] It should be noted that the terms "first", "second", etc. in the specification and claims of the present application and in the above-described drawings are used to distinguish similar objects, and do not necessarily have to be used to describe a specific order or sequence. It should be understood that the data thus used can be interchanged under appropriate circumstances, so that the embodiments of the application described herein can encompass the order implementation other than those illustrated or described herein. In addition, the terms "include" and "have" and any variations thereof are intended to cover non-exclusive inclusion, for example, a process, method, system, product or device including a series of steps or units does not have to be limited to the clearly listed steps or units, but can include other steps or units not clearly listed or inherent to these processes, methods, products or devices.

[0029] Embodiment one

[0030] Referring to Figure 1 , a flowchart of a grid-connected detection method of an AC-DC power distribution system provided by an embodiment of the present application is shown, which can be executed by an AC-DC power distribution system grid-connected detection device. The AC-DC power distribution system grid-connected detection device can be realized in the form of hardware and / or software, and can be configured in a computer device. As shown in Figure 1 , the method comprises:

[0031] Step 101, establishing a power flow model of the AC-DC power distribution system before the distributed power source is connected to the grid, and obtaining time-series power flow results according to the power flow model.

[0032] The AC-DC power distribution system is a system for power transmission and distribution, which combines AC and DC current forms. In the AC-DC power distribution system, AC is used for long-distance power transmission and large-scale power distribution because it has lower energy loss during transmission; while DC is often used for precise control of power equipment, electronic equipment and some special applications, such as motor drive, battery charging and data transmission, etc. The AC-DC power distribution system can flexibly switch and adjust the current type according to the demand, ensuring efficient and stable power supply to various power equipment.

[0033] Distributed power source grid connection refers to connecting the distributed power source with the power grid, so that it can work with the power grid to supply or absorb power. Distributed power source grid connection needs to solve the problems of power synchronization, dispatching and protection.

[0034] The time-series power flow results mainly refer to the time-series changes of power, voltage, load and other electrical parameters of the AC-DC power distribution system at different time points within a certain time range.

[0035] In the embodiment, the time sequence analysis is performed on the AC-DC power distribution system by the power flow model, so that the time sequence changes of the electrical parameters such as power, voltage and load of the AC-DC power distribution system at different time points are evaluated, and the time sequence power flow results help the scheduling and stability analysis of the AC-DC power distribution system. Such analysis is generally important for the stability, optimization of power distribution of the AC-DC power distribution system and processing of the uncertainty and volatility brought by the distributed power supply.

[0036] Exemplarily, the power flow model includes an AC grid model, a DC network model, a voltage source converter model and a distributed power supply model.

[0037] In an embodiment of the application, the step 101 can include the following steps:

[0038] The step 1011 includes establishing the AC grid model according to the control strategy of the voltage source converter.

[0039] The voltage source converter (VSC) is a power electronic device capable of converting DC power into AC power, and its main function is to accurately control the flow direction of electric energy and the transmission of power by adjusting the amplitude, frequency and phase of the output voltage.

[0040] In the embodiment, a mathematical model (i.e., the AC grid model) simulating the behavior of the AC grid is constructed by the control method of the voltage source converter. The control strategy usually involves adjusting the output voltage, frequency and phase of the voltage source converter, so as to realize the stability of the voltage and frequency parameters of the AC-DC power distribution system.

[0041] Exemplarily, the voltage source converter can operate under different control strategies, and different control strategies have a direct impact on the AC grid model established by the voltage source converter on the AC side and the representation of the power flow equation. For example, when the voltage source converter operates under constant power control, the AC grid model established by the voltage source converter on the AC side is a constant power source, and the power flow equation can be represented as:

[0042]

[0043] In the formula, P i represents the active power injected by node i, Q i represents the reactive power injected by node i, n represents the number of nodes, V i represents the voltage amplitude of node i, V j represents the voltage amplitude of node j, G ij represents the real part element of the node admittance matrix, B ij represents the imaginary part element of the node admittance matrix, θ ij represents the voltage phase angle of node i and node j, Ps Indicates the active power injected into the DC side, Q s Indicates the reactive power injected into the DC side.

[0044] When a voltage source converter operates in voltage control mode, the AC side can be treated as a PV node, requiring active power flow engineering. For AC / DC distribution systems containing multiple voltage source converters, a master-slave control strategy can be used to coordinate the operation of each voltage source converter to establish an AC grid model.

[0045] Step 1012: Establish a DC network model according to the electrical parameters of the DC network.

[0046] DC networks transmit electrical energy through direct current. Unlike AC grids, DC grids are typically used in application scenarios such as long-distance power transmission, efficient power conversion, and integration of renewable energy.

[0047] In this embodiment, a DC network model is constructed using DC grid electrical parameters (such as voltage, current, resistance, and conductance) to reflect the behavior and operating characteristics of the DC grid. This DC network model accurately describes and analyzes the dynamic behavior of the DC network and assesses its performance under various operating conditions, such as voltage fluctuations, current variations, and power transmission.

[0048] For example, the power flow equation for the DC network model can be calculated using the following formula:

[0049]

[0050] Where, I dci represents the injected current of node i, R ik Indicates DC resistance, V dci represents the injected voltage at node i, V dcj represents the injected voltage at node j.

[0051] For example, for a single-stage symmetrically grounded AC / DC power distribution system, the injected current I dci It can also be calculated using the following power flow equation:

[0052]

[0053] Where, I dci represents the injected current of node i, P dci represents the injected active power of node i, V dci represents the injected voltage at node i.

[0054] Step 1013: Establish a voltage source converter model according to the electrical parameters of the voltage source converter.

[0055] In this embodiment, by analyzing the electrical parameters of a voltage source converter (VSC) (such as the electrical parameters of a transformer, filter, commutation impedance, and rectifier), a voltage source converter model is established to describe the behavior of the voltage source converter in an AC / DC power distribution system.

[0056] Exemplarily, the voltage source converter model is calculated using the following power flow equation:

[0057] S s =V s I tf ;

[0058] V f =V s +I tf ·Z tf ;

[0059] Q f =-B f ·|V f | 2 ;

[0060] S cf =V c I cf ;

[0061] P loss =a+b·|I c |+c·|I c | 2 ;

[0062] P c =-P dci -P loss ;

[0063] Where S s represents the complex power injected into the AC bus S, V s Indicates the voltage of the AC bus S, I tf Represents the current on the converter transformer, V f represents the voltage of AC bus f, Z tf Indicates the equivalent impedance of the AC transformer, Q f Indicates the reactive power of the AC bus f, B f Represents the admittance of the AC filter, I cf Represents the current on the commutation impedance, S cf Represents the apparent power flowing through the commutation impedance, V c Represents the voltage of the commutation impedance, I cf Indicates the current flowing through the commutation impedance, P loss represents the loss of the voltage source converter, and a, b and c represent the loss coefficients.

[0064] Step 1014, predicting the distributed power output curve according to the weather condition data, and establishing the distributed power model according to the distributed power output curve.

[0065] In the embodiment, the output curve (i.e. power generation output curve) of the distributed power (such as wind turbine and photovoltaic distributed power) is predicted by analyzing the weather condition data (such as wind speed, light intensity, etc.), and the distributed power model is established according to the predicted output curve, so as to describe the operation characteristics of the distributed power model in the AC-DC power distribution system, which can effectively simulate the power generation fluctuation and variation law of the distributed power.

[0066] For example, the output characteristics of the wind turbine and photovoltaic distributed power are affected by the weather conditions such as wind speed and light intensity, and the distributed power output curve can be predicted in real time through the weather condition data. When the distributed power is connected to the grid through the AC side, the grid connection point can be equivalent to a PQ node or a PV node. For example, if the grid connection point is equivalent to a PQ node, the power flow equation of the AC side of the distributed power model can be modified as:

[0067]

[0068] In the formula, P i represents the active power injected by node i, Q i represents the reactive power injected by node i, n represents the number of nodes, V i represents the voltage amplitude of node i, V j represents the voltage amplitude of node j, G ij represents the real part element of the node admittance matrix, B ij represents the imaginary part element of the node admittance matrix, θ ij represents the voltage phase angle of node i and node j, P s represents the active power injected by the DC side, Q s represents the reactive power injected by the DC side, P DG，t represents the active power injected by the distributed power t, Q DG，t represents the reactive power injected by the distributed power t.

[0069] For example, when the distributed power is connected to the grid through the DC side, the power generation unit does not generate reactive power, and the power flow equation of the DC side of the distributed power model can be modified as:

[0070]

[0071] In the formula, P dci represents the active power injected by node i, P DG,t represents the active power injected by the distributed power t, V dci represents the injected voltage of node i, R ik represents the DC resistance, Vdcj represents the injection voltage of node j.

[0072] According to the alternating current power grid model, the direct current power grid model, the voltage source converter model and the distributed power supply model, corresponding time sequence flow results can be obtained.

[0073] Step 102, reliability calculation is performed on the AC-DC power distribution system to obtain reliability calculation indexes.

[0074] In the embodiment, the reliability calculation is performed on the AC-DC power distribution system by using the reliability network equivalent technology to evaluate the stability and fault resistance of the AC-DC power distribution system under different working conditions. The reliability indexes (such as the annual average power outage time of the load and the average power outage time of the distributed power supply) can be calculated by simplifying the structure model of the AC-DC power distribution system, which helps to identify potential risks and weak links.

[0075] In an embodiment of the application, step 102 can include the following steps:

[0076] Step 1021, a fault mode and effect cause matrix is obtained according to the topology structure and the shortest power supply path analysis of the AC-DC power distribution system.

[0077] In the embodiment, as shown in Figure 2 The DC power distribution grid topology structure diagram is shown in the figure, 1-7 are DC buses, DG is a distributed power supply, q2, q4, q5 and q7 represent the failure probability of the disconnector, and LD1-LD7 are DC loads. The fault mode and effect cause matrix FMECM describing the influence of branch faults in the AC-DC power distribution grid on the upstream and downstream loads can be calculated by analyzing the topology structure and the shortest power supply path of the AC-DC power distribution system.

[0078] For example, the calculation of the fault mode and effect cause matrix FMECM includes: using a topology search algorithm to traverse the entire AC-DC power distribution grid to determine the upstream and downstream branches of each load point, identifying and marking important nodes and branches that may have a greater impact on the stability of the AC-DC power distribution system and the power supply of the load when a fault occurs. The topology search algorithm includes but is not limited to depth-first search and breadth-first search algorithms.

[0079] Further, for each load point of the AC-DC power distribution grid, the shortest path algorithm is used to calculate the shortest power supply path from the power supply point to the load point, and the information of the path is recorded and stored, including the branches, buses and corresponding impedance or distance parameters on the path. The shortest path algorithm includes but is not limited to the shortest path algorithm, Floyd algorithm and greedy algorithm based on spatial direction.

[0080] Finally, for each branch fault condition of the AC-DC distribution network, the power flow calculation or fault analysis method is used to evaluate the impact of the fault on the upstream and downstream of the load, and the corresponding elements of the fault mode and impact cause matrix FMECM are calculated and filled according to the evaluation results as follows:

[0081]

[0082] In the formula, FMECM represents the fault mode and impact cause matrix, q i represents the fault probability of the i th protection device in the AC-DC distribution system.

[0083] Step 1022, calculate the load type matrix according to the fault mode and impact cause matrix, and convert the load type matrix into a fault maintenance impact time matrix.

[0084] In this embodiment, by analyzing the fault mode and impact cause matrix, the response and impact of different types of loads under fault conditions are obtained, thereby forming a load type matrix. Then, the load type matrix is converted into a fault maintenance impact time matrix, which is used to quantify the recovery time required by various loads after a fault occurs. The recovery time of different load types in the AC-DC distribution system when a fault occurs is evaluated and predicted, thereby helping to optimize the fault response strategy of the AC-DC distribution system and improve the reliability and recovery efficiency of the AC-DC distribution system.

[0085] For example, the load failure rate index is calculated according to the fault mode and impact cause matrix FMECM, and the calculation formula is as follows:

[0086]

[0087] In the formula, λ load-n represents the failure rate of load n, λ branch-n represents the failure rate of branch n, and FMECM represents the fault mode and impact cause matrix.

[0088] The fault probability of the protection device in the AC-DC distribution system is set to 0, and the fault mode and impact cause matrix FMECM is recalculated, thereby obtaining the load type matrix LTM.

[0089] The branch switch time in the load type matrix LTM is modified to 0, and the corresponding branch maintenance time is modified to 1, thereby obtaining the fault maintenance impact time matrix FMECM i .

[0090] Step 1023, calculate the annual average outage time of the load according to the fault mode and impact cause matrix and the fault maintenance impact time matrix.

[0091] In the embodiment, the annual average outage time of the load is calculated by analyzing the fault mode and effect cause matrix and the fault maintenance effect time matrix of the AC-DC power distribution system, the influence degree of the AC-DC power distribution system on various loads under different fault conditions is quantified, and in particular, the duration of the outage of the load is quantified. Through the calculation, the reliability of the AC-DC power distribution system can be evaluated, and the possible weak links can be identified.

[0092] For example, the annual average outage time of the load can be calculated by the following formula:

[0093]

[0094] In the formula, U load-n represents the annual average outage time of the load, λ branch-n represents the annual average time of the branch, FMECM i represents the fault maintenance effect time matrix, and FMECM represents the fault mode and effect cause matrix.

[0095] In step 1024, the island division is performed on the load of the AC-DC power distribution system to obtain an island range, and a path recovery matrix of the distributed power supply to the load in the island range is constructed.

[0096] In the embodiment, in the AC-DC power distribution system, the island division is performed on the load to determine which areas will become island ranges (i.e., areas that cannot be connected to the AC-DC power distribution system) when a fault occurs. Then, the path recovery matrix of the distributed power supply to the load in the island range is constructed, and how the distributed power supply provides power recovery services for the load in the island range is analyzed, so as to improve the resilience and fault recovery capability of the AC-DC power distribution system.

[0097] For example, the following optimization equation can be used for the island division:

[0098]

[0099] In the formula, S k is a load importance coefficient, M is a load set in the island range, S DG is a maximum power supply capacity, Lk is the power consumed by the load k, and f L is an optimization objective.

[0100] On the basis of obtaining the island range, the influence of the distributed power supply needs to be supplemented in the reliability calculation, and the path recovery matrix L DG(m,n) of the distributed power supply to the load in the island range can be constructed, and the expression of each element is as follows:

[0101]

[0102] Where D represents the island range, m represents the fault branch, n represents the corresponding node load, and L DG(m,n) . represents the load path recovery matrix.

[0103] Step 1025: Obtain a distributed power supply fault maintenance impact time matrix according to the load type matrix and the load path restoration matrix.

[0104] In this embodiment, a distributed power supply (DG) fault maintenance impact time matrix is ​​calculated by combining the load type matrix and the load path restoration matrix. The load type matrix describes the characteristics of different load types, while the load path restoration matrix reflects the time required for DGs to restore power to loads within different islands. This step allows for the assessment of the time required for various load types to recover after a DG fault, as well as its impact on the overall reliability of the AC / DC distribution system.

[0105] For example, the distributed generation load type matrix LTM can be calculated by the load type matrix and the load path restoration matrix. DG , the calculation formula is as follows:

[0106] LTM DG =LTM+L DG ;

[0107] Where, LTM DG Indicates that the distributed power generation complies with the type matrix, L DG represents the load path restoration matrix, and LTM represents the load type matrix.

[0108] Distributed generation load type matrix LTM DG The branch switching time in is changed to 0, the corresponding branch switching time plus the distributed power supply startup time is changed to 1, and the corresponding branch repair time is changed to 2, and the distributed power supply fault maintenance impact time matrix FMITM is obtained. DG .

[0109] Step 1026: Calculate the average power outage time of the distributed power supply based on the distributed power supply fault maintenance impact time matrix and the failure mode and impact cause matrix.

[0110] In this embodiment, the average power outage time of distributed power sources is calculated, and the impact of distributed power sources on load recovery in the event of a fault or power outage in the AC / DC distribution system is evaluated by combining the distributed power source fault maintenance impact time matrix and the failure mode and impact cause matrix.

[0111] For example, the calculation formula for the average power outage time of distributed power generation is as follows:

[0112]

[0113] FMECM DG is the distributed power failure maintenance influence time matrix, U load-n represents the annual average outage time of the load, λ branch-n represents the annual average time of the branch, and FMECM represents the failure mode and influence cause matrix.

[0114] Step 103, constructing a comprehensive performance index of the AC-DC power distribution system according to the time sequence power flow result and the reliability calculation index.

[0115] In this embodiment, the time sequence power flow result and the reliability calculation index are combined to comprehensively evaluate the overall performance of the AC-DC power distribution system. The time sequence power flow result reflects the power flow state of the AC-DC power distribution system at different time points, while the reliability calculation index reflects the reliability performance of the AC-DC power distribution system when facing failures. By combining the time sequence power flow result and the reliability calculation index, a comprehensive performance index can be obtained to help evaluate the comprehensive performance of the AC-DC power distribution system under normal operation and failure conditions.

[0116] In an embodiment of the present application, the comprehensive performance index includes an electric energy quality index, and the electric energy quality index at least includes a voltage deviation rate and a line loss rate.

[0117] The calculation formula of the voltage deviation rate is:

[0118]

[0119] The calculation formula of the line loss rate is:

[0120]

[0121] wherein, V node represents the voltage deviation rate, N represents the number of nodes, T represents the statistical time, V k represents the operating voltage of the AC-DC power distribution system at each time, V k，R represents the rated voltage, S line represents the line loss rate, L represents the number of branches, and P k represents the line loss of the AC-DC power distribution system, S N represents the rated capacity of the AC-DC power distribution system.

[0122] In an embodiment of the present application, the comprehensive performance index further includes a reliability index, and the reliability index at least includes a user average outage duration and an average outage rate.

[0123] The calculation formula of the user average outage duration is:

[0124]

[0125] The calculation formula of the average outage rate is:

[0126]

[0127] wherein I CAIDI represents the average outage duration of the user, L D represents the number of loads, U i represents the annual average outage time of the load, N i represents the number of users, λ i represents the load failure rate, I ASAI represents the average outage rate.

[0128] In an embodiment of the present application, the comprehensive performance index further comprises a system vulnerability index, and the system vulnerability index at least comprises a system node vulnerability index and a system branch vulnerability index.

[0129] wherein the calculation formula of the system node vulnerability index is:

[0130]

[0131] The calculation formula of the system branch vulnerability index is:

[0132]

[0133] wherein NB k represents the node vulnerability index, k represents the node number, l k represents the load loss when the node k fails, l N represents the total load of the AC-DC power distribution system, S1 represents the power supply set, L2 represents the load set, R ij (k) represents a judgment function of whether the node k is on the power supply path, Z represents the total power supply path, NB s represents the system node vulnerability index, N represents the number of nodes, LB T represents the branch vulnerability index, T represents the branch number, l T represents the load loss when the branch T fails, R ij (T) represents a judgment function of whether the branch T is on the power supply path, LBs represents the system branch vulnerability index, and L represents the number of branches.

[0134] Step 104, generating the operation state information of the AC-DC power distribution system for connecting the distributed power supply according to the comprehensive performance index.

[0135] In the embodiment, the stability, reliability and efficiency of the AC-DC distribution system in the process of grid connection are evaluated by integrating the time sequence flow results and reliability calculation indexes into a comprehensive performance index, and generating the operation state information of the AC-DC distribution system in the process of grid connection of the distributed power by the fuzzy comprehensive evaluation method, so as to ensure that the AC-DC distribution system can be smoothly connected and stably operated under different load and power conditions. The fuzzy comprehensive evaluation method can process the complex relationship and uncertainty between different indexes, and finally obtain a comprehensive evaluation result (i.e. the operation state information of the AC-DC distribution system in the process of grid connection of the distributed power) by comprehensively combining the influences of various performance indexes by weighted average method. The operation state information refers to the real-time operation parameters and performance of the AC-DC distribution system in the process of grid connection, such as voltage, current, power and other electrical data, which are used to monitor and optimize the operation state of the AC-DC distribution system.

[0136] In an embodiment of the present application, step 104 can include the following steps:

[0137] Step 1041, calculating the weight matrix of the comprehensive performance index by using the analytic hierarchy process.

[0138] In the embodiment, the analytic hierarchy process is a commonly used method for determining the weight of the comprehensive performance index, and is particularly suitable for the comprehensive performance index with multiple levels. First, the comprehensive performance index needs to be determined, which is each performance index in the target layer, performance layer and index layer. Then, the importance of each performance index in the same level with respect to a certain evaluation index in the previous level is compared, and a judgment matrix is constructed. Finally, the judgment matrix is subjected to consistency check and the weight is calculated to obtain the weight matrix A.

[0139] Step 1042, constructing an evaluation set, and calculating the fuzzy judgment matrix of the comprehensive performance index according to the evaluation set by using a triangular membership function.

[0140] The evaluation set is a language description of the performance of the comprehensive performance index, and the evaluation set is as follows:

[0141] v = (V1, V2, V3, V4);

[0142] In the formula, v represents the evaluation set, v1 represents excellent, v2 represents good, v3 represents general, and v4 represents poor.

[0143] The triangular membership function is used to describe the membership degree of an element to a fuzzy set, and the membership degree of each index in the comprehensive performance index with respect to the evaluation set v is calculated to form a fuzzy judgment matrix R. The expression of the triangular membership function is as follows:

[0144]

[0145] In the formula, R(x) represents a triangular membership function, and a, b and c each represent a parameter of the triangular membership function.

[0146] The parameters a, b and c determine the shape and position of the triangular membership function.

[0147] In this embodiment, the evaluation set is formed according to different evaluation values covered by the comprehensive performance index. The evaluation values are fuzzified by using the triangular membership function, and then the fuzzy judgment matrix of the comprehensive performance index is obtained. The qualitative or uncertain evaluation values are converted into fuzzy values, thereby solving the deviation or uncertainty that may occur in the traditional evaluation method, and making the evaluation process more flexible and accurate.

[0148] In step 1043, the evaluation matrix of the comprehensive performance index is calculated according to the weight matrix and the fuzzy judgment matrix, and the fuzzy evaluation result is obtained.

[0149] In this embodiment, the weight matrix of the comprehensive performance index obtained by the analytic hierarchy process is combined with the fuzzy judgment matrix obtained by the triangular membership function to obtain an evaluation matrix of the comprehensive performance index. The evaluation matrix reflects the influence degree of the comprehensive performance index on the overall evaluation of the AC-DC distribution system, and the final fuzzy evaluation result is obtained by the fuzzy comprehensive evaluation method. The relative importance and uncertainty of different performance indexes are quantified to obtain a comprehensive and objective evaluation result, thereby accurately evaluating the comprehensive performance of the AC-DC distribution system.

[0150] For example, the evaluation matrix B is calculated by the weight matrix A and the fuzzy judgment matrix R, and the calculation formula is as follows:

[0151] B=A·R;

[0152] In the formula, B represents the evaluation matrix, A represents the weight matrix, and R represents the fuzzy judgment matrix.

[0153] In step 1044, the fuzzy evaluation result is converted into motion state information of the AC-DC distribution system for distributed power grid connection.

[0154] In this embodiment, the fuzzy evaluation result is converted into motion state information, and the AC-DC distribution system is comprehensively evaluated for distributed power grid connection, which facilitates comparison and sorting of different distributed power grid connection strategies, and selection of the most reasonable distributed power grid connection strategy.

[0155] For example, in order to verify the feasibility of the grid connection detection method of the AC-DC distribution system provided in the embodiment, the test system IEEE RBTS 6-feeder F4 of power system reliability analysis is used as a test example. The test system is powered by a voltage source converter as a DC distribution network, and constitutes a complex AC-DC distribution system.Figure 3 is a schematic diagram of an AC / DC power distribution system topology provided by an embodiment of the present application, as shown in Figure 3 The LP1-LP13 and LP18-LP22 are AC loads, the LP14-LP17 are DC loads, the L1-L10 and L15-L29 are AC transmission lines, the L11-L14 are DC transmission lines, and the VSC is a voltage source converter in the AC / DC power distribution system.

[0156] In order to analyze the influence of different grid-connected strategies and grid-connected positions of the distributed power on the AC / DC power distribution system, four different grid-connected strategies are set, as shown in Table 1.

[0157] Table 1. Schematic table of different grid-connected strategies of distributed power

[0158]

[0159]

[0160] The indicators of the AC / DC power distribution system before and after the grid connection of the different grid-connected strategies of the distributed power are calculated respectively, and the calculation results are shown in Table 2.

[0161] Table 2. Schematic table of calculation results of indicators of the AC / DC power distribution system before and after the grid connection of the different grid-connected strategies of the distributed power.

[0162]

[0163] As can be seen from Table 2, the voltage deviation rate of strategy A is 0.0312, which is reduced by 38.22% compared with 0.0505 before the grid connection; the line loss rate of strategy B is 0.0138, which is reduced by 7.38% compared with 0.0149 before the grid connection; the average duration of user power outage of strategy A is 5.485, which is reduced by 18.11% compared with 6.698 before the grid connection; the average outage rate of strategy A is 0.99865, which is increased by 0.03% compared with 0.9983 before the grid connection; the system node vulnerability index and the system branch vulnerability index of strategy A are 0.0916 and 0.0814 respectively, which are reduced by 43.36% and 43.47% respectively compared with 0.162 and 0.144 before the grid connection. Therefore, the reasonable grid-connected strategy of the distributed power significantly improves the power supply quality and safety and reliability of the AC / DC power distribution system.

[0164] In order to evaluate the comprehensive influence of the different grid-connected strategies of the distributed power on the AC / DC power distribution system, the fuzzy comprehensive evaluation method is used to measure and evaluate the performance indicators of each strategy. The evaluation performance index weight is calculated by the Delphi method, and the calculation results are shown in Table 3.

[0165] Table 3. Schematic table of evaluation index weight

[0166]

[0167]

[0168] The comprehensive evaluation results and the specific scores of each comment are shown in Table 4.

[0169] Table 4. Schematic diagram of results of comprehensive evaluation results and specific scores of each comment

[0170] Strategy excellent v1 Good v2 [generally v3] Poor v4 Score Pre-grid 0.1386 0.2148 0.2336 0.2747 7.1107 A 0.1970 0.4033 0.2736 0.1221 8.6419 B 0.1517 0.3036 0.1824 0.2620 7.5414 C 0.1935 0.2793 0.3804 0.1430 8.4925 D 0.1944 0.2615 0.3917 0.1487 8.4720

[0171] As can be seen from Table 4, the grid-connected strategy of the distributed power supply significantly improves the comprehensive performance of the AC-DC power distribution system. Specifically, the comprehensive score of strategy A is the highest, indicating that its performance on each evaluation index is the best. Therefore, when selecting the grid-connected strategy of the distributed power supply, strategy A should be given priority.

[0172] In the embodiment of the application, a power flow model of the AC-DC power distribution system before the distributed power supply is connected to the grid is established, and a time sequence power flow result is obtained according to the power flow model. The reliability of the AC-DC power distribution system is calculated to obtain a reliability calculation index. A comprehensive performance index of the AC-DC power distribution system is constructed according to the time sequence power flow result and the reliability calculation index. The operation state information of the AC-DC power distribution system for the distributed power supply to be connected to the grid is generated according to the comprehensive performance index. According to the operation state information, the weak links of the AC-DC power distribution system that need to be improved can be determined, and technical support and guidance can be provided for the grid-connected strategy of the distributed power supply, which is conducive to promoting the safe and reliable operation of the AC-DC power distribution system. Through optimized scheduling and power supply planning, the operation efficiency of the AC-DC power distribution system can be improved, the operation cost can be reduced, and the accuracy of the grid-connected detection of the AC-DC power distribution system can be improved.

[0173] Embodiment two

[0174] Figure 4 A structure diagram of a grid-connected detection device of an AC-DC power distribution system provided for the embodiment two of the application is shown in FIG. 1, which comprises: Figure 4

[0175] A time sequence power flow result acquisition module 401 is configured to establish a power flow model of the AC-DC power distribution system before the distributed power supply is connected to the grid, and obtain a time sequence power flow result according to the power flow model.

[0176] A reliability calculation index acquisition module 402 is configured to calculate the reliability of the AC-DC power distribution system to obtain a reliability calculation index.

[0177] A comprehensive performance index calculation module 403 is configured to construct a comprehensive performance index of the AC-DC power distribution system according to the time sequence power flow result and the reliability calculation index.

[0178] ​The motion state information generation module 404 is configured to generate operation state information of the AC-DC power distribution system for grid connection of the distributed power supply according to the comprehensive performance index.

[0179] In one embodiment of the application, the power flow model comprises an AC power grid model, a DC network model, a voltage source converter model and a distributed power supply model; and the time sequence power flow result acquisition module 401 comprises:

[0180] The AC power grid model construction module is configured to establish the AC power grid model according to the control strategy of the voltage source converter.

[0181] The DC network model construction module is configured to establish the DC network model according to the electrical parameters of the DC network.

[0182] The voltage source converter model construction module is configured to establish the voltage source converter model according to the electrical parameters of the voltage source converter.

[0183] The distributed power supply model construction module is configured to predict a distributed power supply output curve according to the meteorological condition data, and establish the distributed power supply model according to the distributed power supply output curve.

[0184] In one embodiment of the application, the reliability calculation index comprises a load annual average outage time and a distributed power supply average outage time; and the reliability calculation index acquisition module 402 comprises:

[0185] The fault mode and influence reason matrix acquisition module is configured to obtain a fault mode and influence reason matrix according to the topology structure and the shortest power supply path analysis of the AC-DC power distribution system.

[0186] The fault maintenance influence time matrix construction module is configured to calculate a load type matrix according to the fault mode and influence reason matrix, and convert the load type matrix into a fault maintenance influence time matrix.

[0187] The load annual average outage time calculation module is configured to calculate a load annual average outage time according to the fault mode and influence reason matrix and the fault maintenance influence time matrix.

[0188] The load path recovery matrix construction module is configured to divide the load of the AC-DC power distribution system into island ranges to construct a distributed power supply load path recovery matrix for the island ranges.

[0189] The fault maintenance influence time matrix construction module is configured to obtain a distributed power supply fault maintenance influence time matrix according to the load type matrix and the load path recovery matrix.

[0190] The distributed power supply average outage time calculation module is configured to calculate a distributed power supply average outage time according to the distributed power supply fault maintenance influence time matrix and the fault mode and influence cause matrix.

[0191] In one embodiment of the present application, the comprehensive performance index comprises an electric energy quality index; the electric energy quality index comprises at least a voltage deviation rate and a line loss rate;

[0192] The calculation formula of the voltage deviation rate is as follows:

[0193]

[0194] The calculation formula of the line loss rate is as follows:

[0195]

[0196] Wherein, V node represents the voltage deviation rate, N represents the number of nodes, T represents the statistical time, V k represents the operating voltage of the AC-DC power distribution system at each time, V k，R represents the rated voltage, S line represents the line loss rate, L represents the number of branches, P k represents the line loss of the AC-DC power distribution system, S N represents the rated capacity of the AC-DC power distribution system.

[0197] In one embodiment of the present application, the comprehensive performance index further comprises a reliability index; the reliability index comprises at least a user average outage duration and an average outage rate;

[0198] The calculation formula of the user average outage duration is as follows:

[0199]

[0200] The calculation formula of the average outage rate is as follows:

[0201]

[0202] Wherein, I CAIDI represents the user average outage duration, L D represents the number of loads, U i represents the load annual average outage time, N i represents the number of users, λ i represents the load failure rate, I ASAI represents the average outage rate.

[0203] In one embodiment of the present application, the comprehensive performance index further comprises a system vulnerability index; the system vulnerability index comprises at least a system node vulnerability index and a system branch vulnerability index;

[0204] The calculation formula of the system node vulnerability index is:

[0205]

[0206] The calculation formula of the system branch vulnerability index is:

[0207]

[0208] Wherein, NB k represents the node vulnerability index, k represents the node number, l k represents the load loss when the node k fails, l N represents the total load of the AC / DC power distribution system, S1 represents the power set, L2 represents the load set, R ij (k) represents a judgment function of whether the node k is on the power supply path, Z represents the total power supply path, NB s represents the system node vulnerability index, N represents the number of nodes, LB T represents the branch vulnerability index, T represents the branch number, l T represents the load loss when the branch T fails, R ij (T) represents a judgment function of whether the branch T is on the power supply path, LB s represents the system branch vulnerability index, L represents the number of branches.

[0209] In one embodiment of the present application, the motion state information generation module 404 comprises:

[0210] A weight matrix calculation module is configured to calculate a weight matrix of the comprehensive performance index by using an analytic hierarchy process.

[0211] A fuzzy judgment matrix calculation module is configured to construct an evaluation set, and calculate a fuzzy judgment matrix of the comprehensive performance index by using a triangular membership function according to the evaluation set.

[0212] A fuzzy evaluation result acquisition module is configured to calculate an evaluation matrix of the comprehensive performance index according to the weight matrix and the fuzzy judgment matrix, and obtain a fuzzy evaluation result.

[0213] A running state information conversion module is configured to convert the fuzzy evaluation result into running state information of the AC / DC power distribution system for grid connection of the distributed power supply.

[0214] The grid-connected detection device of the AC-DC power distribution system provided by the embodiment of the present application can execute the grid-connected detection method of the AC-DC power distribution system provided by any embodiment of the present application, and has the corresponding function modules and beneficial effects of executing the grid-connected detection method of the AC-DC power distribution system.

[0215] Embodiment three

[0216] Referring to Figure 5 , a structural schematic diagram of a computer device provided by an embodiment of the present application is shown. The computer device is intended to represent various forms of digital computers, such as laptops, desktops, workstations, personal digital assistants, servers, mainframes, and other appropriate computers. The computer device can also represent various forms of mobile devices, such as personal digital processors, cellular telephones, smart phones, wearable devices (such as headsets, glasses, watches, etc.), and other similar computing devices. The components shown here, their connections, and their functions, are meant to be examples only, and are not intended to limit the implementations of the present application described and / or claimed in this document.

[0217] As Figure 5 shown, the computer device 10 includes at least one processor 11, and a memory, such as a read-only memory (ROM) 12, a random access memory (RAM) 13, etc., which is communicatively connected to the at least one processor 11, wherein the memory stores a computer program that can be executed by the at least one processor. The processor 11 can execute various appropriate actions and processes according to the computer program stored in the read-only memory (ROM) 12 or loaded from the storage unit 18 into the random access memory (RAM) 13. In the RAM 13, various programs and data required for the operation of the computer device 10 can also be stored. The processor 11, the ROM 12, and the RAM 13 are connected to each other through a bus 14. An input / output (I / O) interface 15 is also connected to the bus 14.

[0218] A plurality of components in the computer device 10 are connected to the I / O interface 15, including: an input unit 16, such as a keyboard, a mouse, etc.; an output unit 17, such as various types of displays, speakers, etc.; a storage unit 18, such as a magnetic disk, an optical disk, etc.; and a communication unit 19, such as a network card, a modem, a wireless communication transceiver, etc. The communication unit 19 allows the computer device 10 to exchange information / data with other devices through a computer network, such as the Internet, and / or various telecommunications networks.

[0219] The processor 11 can be various general and / or special purpose processing components with processing and computing capabilities. Some examples of the processor 11 include, but are not limited to, a central processing unit (CPU), a graphics processing unit (GPU), various specialized artificial intelligence (AI) computing chips, various processors running machine learning model algorithms, a digital signal processor (DSP), and any suitable processor, controller, microcontroller, and the like. The processor 11 performs various methods and processes described above, such as the grid-connected detection method of the AC-DC power distribution system.

[0220] In some embodiments, the grid-connected detection method of the AC-DC power distribution system can be implemented as a computer program tangibly embodied in a computer readable storage medium, such as the storage unit 18. In some embodiments, part or all of the computer program can be loaded and / or installed onto the computer device 10 via the ROM 12 and / or the communication unit 19. When the computer program is loaded onto the RAM 13 and executed by the processor 11, one or more steps of the grid-connected detection method of the AC-DC power distribution system described above can be performed. Alternatively, in other embodiments, the processor 11 can be configured to perform the grid-connected detection method of the AC-DC power distribution system by any other suitable means, such as by means of firmware.

[0221] Various implementations of the systems and techniques described above can be realized in digital electronic circuitry, integrated circuitry, a field programmable gate array (FPGA), an application specific integrated circuit (ASIC), a system on a chip (SOC), a programmable logic device (PLD), a computer hardware, firmware, software, and / or combinations thereof. These various implementations can include implementation in one or more computer programs that are executable and / or interpretable on a programmable system including at least one programmable processor, which can be special or general purpose, coupled to receive data and instructions from, and to transmit data and instructions to, a storage system, at least one input device, and at least one output device.

[0222] Computer programs used to implement the methods of the application can be written in any combination of one or more programming languages. These computer programs can be provided to a processor of a general purpose computer, special purpose computer, or other programmable data processing apparatus to produce a machine, such that the computer program, when executed by the processor of the machine, implements the functions / acts specified in the flowcharts and / or block diagrams. The computer program can be executed entirely on a machine, partially on a machine, partially on a machine as a stand-alone software package, partially on a machine and partially on a remote machine or entirely on a remote machine or server.

[0223] In the context of the present application, a computer-readable storage medium can be a tangible medium that can contain or store a computer program for use by or in connection with an instruction execution system, apparatus, or device. A computer-readable storage medium can include, but is not limited to, an electronic, magnetic, optical, electromagnetic, infrared, or semiconductor system, apparatus, or device, or any suitable combination of the foregoing. Alternatively, a computer-readable storage medium can be a machine-readable signal medium. More specific examples of a machine-readable storage medium will include one or more lines of a program of instructions in a transitory signal, a portable computer diskette, a hard disk, a random access memory (RAM), a read-only memory (ROM), an erasable programmable read-only memory (EPROM or Flash memory), an optical fiber, a portable compact disc read-only memory (CD-ROM), an optical storage device, a magnetic storage device, or any suitable combination of the foregoing.

[0224] To provide for interaction with a user, the systems and techniques described here can be implemented on a computer device having a display device (e.g., a CRT (cathode ray tube) or LCD (liquid crystal display) monitor) for displaying information to the user and a keyboard and a pointing device (e.g., a mouse or a trackball) by which the user can provide input to the computer device. Other kinds of devices can be used to provide for interaction with a user as well; for example, feedback provided to the user can be any form of sensory feedback (e.g., visual feedback, auditory feedback, or tactile feedback); and input from the user can be received in any form, including acoustic, speech, or tactile input.

[0225] The systems and techniques described here can be implemented in a computing system that includes a back end component (e.g., as a data server), or that includes a middleware component (e.g., an application server), or that includes a front end component (e.g., a user computer having a graphical user interface or a Web browser through which a user can interact with an implementation of the systems and techniques described here), or any combination of such back end, middleware, or front end components. The components of the system can be interconnected by any form or medium of digital data communication (e.g., a communication network). Examples of communication networks include a local area network (LAN), a wide area network (WAN), a blockchain network, and the Internet.

[0226] The computing system can include clients and servers. A client and server are generally remote from each other and typically interact through a communication network. The relationship of client and server arises by virtue of computer programs running on the respective computers and having a client-server relationship to each other. Servers can be cloud servers, also known as cloud computing servers or cloud hosts, which are a host product in the cloud computing service system to solve the defects of great management difficulty and weak business scalability in traditional physical hosts and VPS services.

[0227] Embodiment four

[0228] The embodiment of the present application also provides a computer program product, which comprises a computer program, and the computer program is executed by a processor to implement the grid-connected detection method of the AC / DC power distribution system provided by any of the embodiments of the present application.

[0229] The computer program code implementing the present application can be written in one or more programming languages or combinations of languages including object oriented languages such as Java, Smalltalk, C++ or conventional procedural programming languages such as the "C" programming language or similar programming languages. The program code can execute entirely on the user's computer, partly on the user's computer, as a stand-alone software package, partly on the user's computer and partly on a remote computer or entirely on the remote computer or server. In the latter scenario, the remote computer can be connected to the user's computer through any type of network, including a local area network (LAN) or a wide area network (WAN), or the connection can be made to an external computer (for example, through the Internet using an Internet Service Provider).

[0230] It should be understood that the steps shown in the above forms of flow can be reordered, added or deleted. For example, the steps described in the present application can be executed in parallel, sequentially or in different orders, as long as the desired results of the technical solutions of the present application can be achieved, which are not limited herein.

[0231] The above detailed description does not constitute a limitation on the protection scope of the present application. Those skilled in the art should understand that various modifications, combinations, sub-combinations and substitutions can be made according to design requirements and other factors. Any modifications, equivalent replacements and improvements made within the spirit and principles of the present application shall be included in the protection scope of the present application.

Claims

1. A grid-connected detection method of an AC / DC power distribution system, characterized in that, The method comprises: establishing a power flow model of the AC-DC power distribution system before the distributed power source is connected to the grid, and obtaining time-series power flow results according to the power flow model; performing reliability calculation on the AC-DC power distribution system to obtain reliability calculation indexes; constructing comprehensive performance indexes of the AC-DC power distribution system according to the time-series power flow results and the reliability calculation indexes; generating operation state information of the AC-DC power distribution system for connecting the distributed power source to the grid according to the comprehensive performance indexes.

2. The method of claim 1, wherein, The power flow model comprises an AC power grid model, a DC network model, a voltage source converter model and a distributed power source model; the establishment of the power flow model of the AC-DC power distribution system before the distributed power source is connected to the grid comprises: establishing the AC power grid model according to the control strategy of the voltage source converter; establishing the DC network model according to the electrical parameters of the DC network; establishing the voltage source converter model according to the electrical parameters of the voltage source converter; predicting the distributed power source output curve according to meteorological condition data, and establishing the distributed power source model according to the distributed power source output curve.

3. The method of claim 1, wherein, The reliability calculation indexes comprise load annual average outage time and distributed power source average outage time; the reliability calculation on the AC-DC power distribution system to obtain the reliability calculation indexes comprises: obtaining a fault mode and influence reason matrix according to the topological structure and shortest power supply path analysis of the AC-DC power distribution system; obtaining a load type matrix according to the fault mode and influence reason matrix, and converting the load type matrix into a fault maintenance influence time matrix; obtaining the load annual average outage time according to the fault mode and influence reason matrix and the fault maintenance influence time matrix; dividing the load of the AC-DC power distribution system into islands to obtain island ranges, and constructing a distributed power source load path recovery matrix for the island ranges; obtaining a distributed power source fault maintenance influence time matrix according to the load type matrix and the load path recovery matrix; obtaining the distributed power source average outage time according to the distributed power source fault maintenance influence time matrix and the fault mode and influence reason matrix.

4. The method of claim 1, wherein, The comprehensive performance indexes comprise power quality indexes; the power quality indexes at least comprise voltage deviation rate and line loss rate; the calculation formula of the voltage deviation rate is: the calculation formula of the line loss rate is: Wherein, V node represents the voltage deviation rate, N represents the number of nodes, T represents the statistical time, V k represents the operating voltage of the AC-DC power distribution system at each time, V k,R represents the rated voltage, S line represents the line loss rate, L represents the number of branches, P k represents the line loss of the AC-DC power distribution system, S N represents the rated capacity of the AC-DC power distribution system.

5. The method of claim 4, wherein, The comprehensive performance indexes further comprise reliability indexes; the reliability indexes at least comprise user average outage duration and average outage rate; the calculation formula of the user average outage duration is: the calculation formula of the average outage rate is: where I CAIDI represents the average outage duration of the user, L D represents the number of loads, U i represents the annual average outage time of the load, N i represents the number of users, λ i represents the failure rate of the load, I ASAI represents the average outage rate.

6. The method of claim 5, wherein, The comprehensive performance indexes further comprise system vulnerability indexes; the system vulnerability indexes at least comprise system node vulnerability indexes and system branch vulnerability indexes; the calculation formula of the system node vulnerability indexes is: the calculation formula of the system branch vulnerability indexes is: where NB k represents the node vulnerability index, k represents the node number, l k represents the load loss when the node k fails, l N represents the total load of the AC / DC distribution system, S1 represents the power supply set, L2 represents the load set, R ij (k) represents a judgment function of whether the node k is on the power supply path, Z represents the total power supply path, NB s represents the system node vulnerability index, N represents the number of nodes, LB T represents the branch vulnerability index, T represents the branch number, l T represents the load loss when the branch T fails, R ij (T) represents a judgment function of whether the branch T is on the power supply path, LB s represents the system branch vulnerability index, L represents the number of branches.

7. The method according to any one of claims 1 to 6, characterized in that, The generation of the operation state information of the AC-DC power distribution system for connecting the distributed power source to the grid according to the comprehensive performance indexes comprises: calculating the weight matrix of the comprehensive performance indexes by using the analytic hierarchy process; construct an evaluation set, and calculate a fuzzy judgment matrix of the comprehensive performance index according to the evaluation set and a triangular membership function; calculate an evaluation matrix of the comprehensive performance index according to the weight matrix and the fuzzy judgment matrix, and obtain a fuzzy evaluation result; convert the fuzzy evaluation result into operation state information of the AC / DC distribution system for grid connection of the distributed power supply.

8. A computer device, comprising: The computer device comprises: one or more processors; a storage device for storing one or more programs; when the one or more programs are executed by the one or more processors, the one or more processors implement the grid connection detection method of the AC / DC distribution system as claimed in any one of claims 1-7.

9. A computer-readable storage medium having a computer program stored thereon, characterized in that: The program is executed by the processor to implement the grid connection detection method of the AC / DC distribution system as claimed in any one of claims 1-7.

10. A computer program product, characterised in that, The computer program product comprises a computer program, which is executed by the processor to implement the grid connection detection method of the AC / DC distribution system as claimed in any one of claims 1-7.

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