A method and device for predicting the acceptance capability of power quality interference sources

Abstract

The present invention discloses a prediction method and device for the acceptance capacity of power quality interference sources, wherein the method comprises: in the distribution network area to be tested, multiple nodes to be connected to the interference source to be connected are determined based on the total access capacity of the current interference source; the capacity to be connected corresponding to each node to be connected is determined; based on multiple types of interference source acceptance capacity prediction index parameters, the total index score of each access scheme under the capacity to be connected corresponding to each node to be connected is calculated through the flow; according to the total index score of each access scheme, the first access capacity and the second access capacity are determined; the difference between the second access capacity and the first access capacity is calculated, and when the difference is greater than or equal to the preset threshold, the first step is returned, and when the difference is less than the preset threshold, the first access capacity is used as the prediction result. The present invention can realize the accurate prediction of the total carrying capacity of interference sources accepted by multiple different nodes to be connected in a large-scale distribution network.

Description

Technical Field

[0001] The present invention relates to the technical field of power distribution networks, and in particular to a method and device for predicting the acceptance capability of power quality interference sources. Background Art

[0002] In recent years, with the continuous increase in the scale of access to power electronic power sources and power-consuming equipment such as distributed power sources, electric vehicles, and electrified railways, the number of nonlinear, impact, and fluctuating power quality interference sources in the distribution network has continued to increase. At present, the disorderly access of various interference sources will threaten the safe and stable operation and power quality of the distribution network. Therefore, it is urgent to carry out scientific and reasonable interference source acceptance capacity prediction, that is, based on the existing load status and power quality level of the distribution network, combined with the power and disturbance characteristics of various interference sources themselves, predict the maximum capacity that can be accessed, and give recommended access locations.

[0003] At present, in the existing technology, the acceptance capacity of power quality interference sources is mainly predicted based on the linear interpolation method. This method can predict interference sources with consistent power timing characteristics. However, for distribution networks with large node scales, the power timing characteristics of different interference sources are inconsistent and unstable, and the multi-point access capacity is uncertain and requires multiple prediction index parameters. Therefore, the linear interpolation method is difficult to accurately predict the total carrying capacity of power quality interference sources in large-scale distribution networks. Summary of the invention

[0004] Therefore, the technical problem to be solved by the present invention is to overcome the problem that the linear interpolation method in the prior art is difficult to accurately predict the total carrying capacity of the power quality interference source acceptance of a large-scale distribution network, thereby providing a method and device for predicting the power quality interference source acceptance capacity.

[0005] According to a first aspect, an embodiment of the present invention provides a method for predicting the acceptance capability of a power quality interference source, comprising the following steps:

[0006] Step S11: in the distribution network area to be tested, determining a plurality of nodes to be connected to the interference source to be connected based on the total access capacity of the current interference source;

[0007] Step S12: determining the to-be-accessed capacity corresponding to each to-be-accessed node according to the total access capacity of the current interference source and the plurality of to-be-accessed nodes;

[0008] Step S13: Based on multiple types of interference source acceptance capacity prediction index parameters, the total index score of each access scheme under the access capacity corresponding to each of the access nodes is calculated through power flow;

[0009] Step S14: determining a first access capacity and a second access capacity according to the total indicator score of each access solution, wherein the second access capacity is greater than the first access capacity;

[0010] Step S15: Calculate the difference between the second access capacity and the first access capacity, and when the difference is greater than or equal to a preset threshold, return to step S11; when the difference is less than the preset threshold, use the first access capacity as a predicted result of the interference source acceptance capacity.

[0011] In one embodiment, the step S11 of determining a plurality of nodes to be connected to the interference source to be connected based on the total access capacity of the current interference source in the distribution network area to be tested comprises:

[0012] Obtaining the total access capacity of the current interference sources in the distribution network area to be tested;

[0013] Determine a third access capacity and a fourth access capacity of any node to be accessed in the distribution network area to be tested, wherein the fourth access capacity is greater than the third access capacity;

[0014] Calculate the upper limit access node number and the lower limit access node number of the interference source in the distribution network area to be tested according to the third access capacity, the fourth access capacity and the total access capacity of the current interference source;

[0015] According to the upper limit of the number of access nodes and the lower limit of the number of access nodes, randomly generate an integer value between the two as the number of access nodes;

[0016] According to the number of access nodes, a plurality of nodes to be accessed are randomly determined in the distribution network area to be tested.

[0017] In one implementation, according to the third access capacity, the fourth access capacity and the total access capacity of the current interference source, the upper limit access node number and the lower limit access node number of the interference source in the distribution network area to be tested are calculated by the following formula:

[0018] N max =min{S total / S min ,N total}

[0019] N min =ceil{S total / S max};

[0020] Among them, S total is the total access capacity of the current interference source, N max is the upper limit number of access nodes, N min is the lower limit number of access nodes, Ntotal is the total number of nodes in the distribution network area to be tested, S max is the fourth access capacity, S min is the third access capacity.

[0021] In one implementation, according to the total access capacity of the current interference source and the multiple nodes to be accessed, the capacity to be accessed corresponding to each node to be accessed is determined by the following formula:

[0022]

[0023] Among them, S total is the total access capacity of the current interference source, S R is the current remaining access capacity, S ub is the upper limit access capacity of the node i to be accessed, S lb is the lower limit access capacity of the node i to be accessed, S i is the capacity of the node i to be connected, S i For S ub With S lb Any random value between S min An integer multiple of .

[0024] In one implementation, based on multiple types of interference source acceptance capacity prediction index parameters, the total index score of each access scheme under the to-be-accessed capacity corresponding to each to-be-accessed node is calculated by the following formula through power flow calculation:

[0025] m i =-100h i ;

[0026]

[0027] Wherein, hi is the predicted value of each index after the distribution network area to be tested is connected to the interference source according to any access scheme, mi is the predicted value of the index after calculation and conversion, and w i is the weight of the ith indicator, and M is the total predicted evaluation value.

[0028] In one implementation, the step of determining the first access capacity and the second access capacity according to the total indicator score of each access solution, wherein the second access capacity is greater than the first access capacity includes:

[0029] If the total index score of any access scheme is greater than or equal to zero, setting the total access capacity of the current interference source as the first access capacity;

[0030] If the total index score of all access solutions is less than zero, the total access capacity of the current interference source is set to the second access capacity.

[0031] In one embodiment, the multiple types of interference source acceptance capacity prediction index parameters include: predicted line N-1 ratio, predicted line load rate, predicted short-circuit current, predicted voltage deviation, predicted harmonic current, predicted harmonic voltage, predicted three-phase imbalance, predicted voltage fluctuation, and predicted line loss rate.

[0032] According to a second aspect, an embodiment of the present invention provides a device for predicting power quality interference source acceptance capability, comprising the following modules:

[0033] A node determination module, used to determine a plurality of nodes to be connected to the interference source to be connected based on the total access capacity of the current interference source in the distribution network area to be tested;

[0034] A scheme determination module, used to determine the to-be-accessed capacity corresponding to each to-be-accessed node according to the total access capacity of the current interference source and the multiple to-be-accessed nodes;

[0035] An index calculation module, used to calculate the total index score of each access scheme under the to-be-accessed capacity corresponding to each to-be-accessed node through power flow based on multiple types of interference source acceptance capacity prediction index parameters;

[0036] A capacity determination module, configured to determine a first access capacity and a second access capacity according to the total indicator score of each access scheme, wherein the second access capacity is greater than the first access capacity;

[0037] The result determination module is used to calculate the difference between the second access capacity and the first access capacity, and when the difference is greater than or equal to a preset threshold, return to the node determination module; when the difference is less than the preset threshold, use the first access capacity as the prediction result of the interference source acceptance capacity.

[0038] According to a third aspect, an embodiment of the present invention provides a computer-readable storage medium, wherein the computer-readable storage medium stores computer instructions, and the computer instructions are used to enable the computer to execute the method for predicting the power quality interference source acceptance capacity described in the first aspect or any embodiment of the first aspect.

[0039] According to the fourth aspect, an embodiment of the present invention provides an electronic device, comprising: a memory and a processor, the memory and the processor are communicatively connected to each other, the memory stores computer instructions, and the processor executes the method for predicting the power quality interference source acceptance capacity described in the first aspect or any embodiment of the first aspect by executing the computer instructions.

[0040] The technical solution of the present invention has the following advantages:

[0041] The present invention discloses a prediction method and device for the acceptance capacity of power quality interference sources, wherein the method comprises: step S11: in a distribution network area to be tested, a plurality of to-be-accessed nodes of the to-be-accessed interference source are determined based on the current total access capacity of the interference source; step S12: according to the current total access capacity of the interference source and the plurality of to-be-accessed nodes, the to-be-accessed capacity corresponding to each to-be-accessed node is determined; step S13: based on multiple types of interference source acceptance capacity prediction index parameters, the total index score of each access scheme under the to-be-accessed capacity corresponding to each to-be-accessed node is calculated through the flow; step S14: according to the total index score of each access scheme, a first access capacity and a second access capacity are determined, and the second access capacity is greater than the first access capacity; step S15: calculating the difference between the second access capacity and the first access capacity, and when the difference is greater than or equal to a preset threshold, returning to step S11, when the difference is less than the preset threshold, taking the first access capacity as the prediction result of the interference source acceptance capacity. The present invention can accurately predict the total carrying capacity of interference sources accepted by multiple different access nodes to be tested in a large-scale distribution network, and takes into account the timing and fluctuation characteristics of different interference sources. Based on the combination of random distribution and binary search method, the optimal distribution scheme for the distribution network interference source carrying capacity and the access capacity of power quality interference sources constrained by power quality level can be finally determined. BRIEF DESCRIPTION OF THE DRAWINGS

[0042] In order to more clearly illustrate the specific implementation methods of the present invention or the technical solutions in the prior art, the drawings required for use in the specific implementation methods or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are some implementation methods of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0043] Figure 1 A first flow chart of a method for predicting power quality interference source acceptance capability in an embodiment of the present invention;

[0044] Figure 2 Schematic diagram of the power distribution network to be tested in an embodiment of the present invention;

[0045] Figure 3 A third flow chart of the method for predicting the power quality interference source acceptance capability in an embodiment of the present invention;

[0046] Figure 4 It is a structural block diagram of a device for predicting the power quality interference source acceptance capability in an embodiment of the present invention;

[0047] Figure 5 FIG. 4 is a hardware structure diagram of an electronic device in an embodiment of the present invention. DETAILED DESCRIPTION

[0048] The technical solution of the present invention will be described clearly and completely below in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0049] In the description of the present invention, it should be noted that the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer", etc., indicating the orientation or positional relationship, are based on the orientation or positional relationship shown in the drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as limiting the present invention. In addition, the terms "first", "second", and "third" are used for descriptive purposes only, and cannot be understood as indicating or implying relative importance.

[0050] In the description of the present invention, it should be noted that, unless otherwise clearly specified and limited, the terms "installed", "connected", and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium, it can also be the internal connection of two components, it can be a wireless connection, or it can be a wired connection. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0051] In addition, the technical features involved in the different embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other.

[0052] In the distribution network, nonlinear, impact and fluctuating power quality interference sources continue to increase. The disorderly access of various interference sources will threaten the safe and stable operation and power quality of the distribution network. In related technologies, for distribution networks with large node scales, the power timing characteristics of different interference sources are inconsistent and unstable, and the multi-point access capacity is uncertain and requires multiple prediction index parameters. Therefore, the linear interpolation method is difficult to accurately predict the total carrying capacity of power quality interference sources in large-scale distribution networks.

[0053] In view of this, in the field of power distribution network technology, an embodiment of the present invention discloses a method for predicting the acceptance capacity of power quality interference sources, such as Figure 1 As shown, the following steps are included:

[0054] Step S11: In the distribution network area to be tested, a plurality of nodes to be connected to the interference source to be connected are determined based on the total access capacity of the current interference source.

[0055] The total access capacity of the current interference source here can be initially half of the power supply capacity of the upper transformer in the distribution network area to be tested, and this value is iteratively updated as the calculation is performed.

[0056] Among them, in the distribution network area to be tested, for example: Figure 2 As shown in the figure, the distribution network to be connected to the interference source may include 3 medium-voltage feeders with a rated voltage of 10kV. The 3 feeders are divided into 3 areas under the medium voltage level, where area 1 includes 8 nodes and 8 lines; area 2 includes 8 nodes and 8 lines; area 3 includes 32 nodes and 32 lines. The low-voltage distribution network is connected to some medium-voltage nodes in area 2 and area 3. The low-voltage distribution network has the same structure and a rated voltage of 380V. A low-voltage distribution network as a whole is an area. Figure 2 In this case, the interference source to be connected is photovoltaic power generation, and its daily power generation curve and the daily load curve of the distribution network to be evaluated are obtained based on actual monitoring data or typical data.

[0057] In one embodiment, Figure 3 As shown, the step S11 of determining a plurality of nodes to be connected to the interference source to be connected based on the total access capacity of the current interference source in the distribution network area to be tested includes:

[0058] Step S110: Obtain the total access capacity of current interference sources in the distribution network area to be tested.

[0059] The current total access capacity of the interference source here can be obtained by calculating the maximum access capacity and the minimum access capacity in the distribution network area to be tested, and taking the average value of the two. The initial value of the maximum access capacity is the total power supply capacity of the distribution network area to be tested, and the total power supply capacity is the total capacity of the upper power supply transformer; the initial value of the minimum access capacity can be 0. Through repeated iterative calculations, the maximum access capacity and the minimum access capacity of the distribution network area to be tested are continuously updated, and the average value of the maximum access capacity and the minimum access capacity is calculated, and the average value is used as the current total access capacity of the interference source in the distribution network area to be tested. For example: set the initial maximum access capacity of the 10kV voltage level grid interference source in the distribution network to be tested to 10MW, and set the initial minimum access capacity of the interference source to 0MW, take the initial value of the current total access capacity of the interference source in the distribution network area to be tested as half of 10MW, and then update the maximum access capacity and the minimum access capacity through calculation, and take the average value of the two as the current total access capacity of the interference source.

[0060] Step S111: determining a third access capacity and a fourth access capacity of any node to be accessed in the distribution network area to be tested, wherein the fourth access capacity is greater than the third access capacity.

[0061] The third access capacity here is the lower limit access capacity of any node i to be accessed, and can also be considered as the minimum access capacity of any node i to be accessed, which can be expressed by S min The fourth access capacity is the upper limit access capacity of any node i to be accessed, and can also be considered as the maximum access capacity of any node i to be accessed, which can be expressed as S max The third access capacity and the fourth access capacity here can be preset according to the total capacity of the interference source to be connected and the grid conditions.

[0062] Step S112: Calculate the upper limit access node quantity and the lower limit access node quantity of the interference source in the distribution network area to be tested according to the third access capacity, the fourth access capacity and the total access capacity of the current interference source.

[0063] In one embodiment, the step S112 of calculating the upper limit access node number and the lower limit access node number of the interference source in the distribution network area to be tested according to the third access capacity, the fourth access capacity and the total access capacity of the current interference source is calculated by the following formula (1):

[0064]

[0065] Among them, S total is the total access capacity of the current interference source, N max is the upper limit of the number of access nodes, N min is the lower limit of the number of access nodes, N total is the total number of access nodes in the distribution network area to be tested, S max is the fourth access capacity, S min It is the third access capacity.

[0066] Step S113: According to the upper limit of the number of access nodes and the lower limit of the number of access nodes, an integer value between the two is randomly generated as the number of access nodes.

[0067] Step S114: According to the number of access nodes, a plurality of nodes to be accessed are randomly determined in the distribution network area to be tested.

[0068] For example: In N max With N min An integer N is randomly generated as the number of access nodes, and N nodes are randomly selected from all accessible nodes as the nodes to be accessed.

[0069] Step S12: Determine the capacity to be accessed corresponding to each node to be accessed according to the total access capacity of the current interference source and a plurality of nodes to be accessed.

[0070] Each node to be accessed here is N nodes to be accessed randomly generated by the above step S113, and the access capacity of each node to be accessed is determined by the following formula (2): An interference source access scheme includes the distribution of nodes to be accessed and their corresponding access capacities.

[0071] In one implementation, the step S12 of determining the capacity to be accessed corresponding to each node to be accessed according to the total access capacity of the current interference source and the plurality of nodes to be accessed is determined by the following formula (2):

[0072]

[0073] Among them, S total is the total access capacity of the current interference source, S R is the current remaining access capacity, S ub is the upper limit access capacity of the node i to be accessed, S lb is the lower limit access capacity of the node i to be accessed, S i is the capacity of the node i to be connected, S i For S ub With S lb Any random value between S min An integer multiple of .

[0074] For example: in the embodiment of the present invention, the minimum access capacity of any single node is set to 10kW; considering factors such as the floor space of the photovoltaic power generation system, the access capacity of any single node in the distribution network to be tested has an upper limit, so the maximum access capacity of any single node is set to 500kW; and the access capacity of any single node is set to an integer multiple of the minimum access capacity of 10kW. According to the total access capacity of the current interference source in the distribution network to be tested, if 500 access nodes are selected from the multiple access nodes randomly determined in the above step S113, the access capacity corresponding to each access node is determined in turn according to formula (2) in the above step S12.

[0075] Step S13: Based on various types of interference source acceptance capacity prediction index parameters, the total index score of each access scheme under the access capacity corresponding to each access node is calculated through power flow.

[0076] In one embodiment, multiple types of interference source acceptance capacity prediction index parameters include: predicted line N-1 ratio, predicted line load rate, predicted short-circuit current, predicted voltage deviation, predicted harmonic current, predicted harmonic voltage, predicted three-phase imbalance, predicted voltage fluctuation, and predicted line loss rate. Among them, the predicted line N-1 ratio, predicted line load rate, and predicted short-circuit current are safety indicators; predicted voltage deviation, predicted harmonic current, predicted harmonic voltage, predicted three-phase imbalance, and predicted voltage fluctuation are high-quality indicators; and predicted line loss rate is an economic indicator.

[0077] The above-mentioned various types of interference source acceptance capacity prediction index parameters can be based on the grid structure parameters of the interference source to be connected to the distribution network to be tested, the load power parameters, the power characteristic parameters of the interference source to be connected, and the power quality characteristic parameters of the interference source to be connected. Among them, the grid structure parameters are static parameters that can be obtained through the ledger. Specifically, they can be the connection relationship of each component of the network, each component such as transformer, generator, equivalent upper grid, impedance, admittance and other electrical parameters of the line. The load power parameters can use monitoring data or experience data of the same type of load. The power quality characteristic parameters of the interference source to be connected can be taken from design data, test data or operation monitoring data. For the power characteristics of the interference source to be connected, it can be obtained through the monitoring data of the same area and the same type of interference source. Taking photovoltaic as an example, its own operation has daily regularity. When extracting the power time series curve, first distinguish different working conditions such as sunny and cloudy days. For each working condition, take the 24-hour output monitoring data of each day under the working condition in a year, and aggregate the arithmetic average value for each hour within the day to obtain the typical daily output curve under each working condition.

[0078] The predicted line N-1 ratio mentioned above can also be called the predicted transformer N-1 ratio. For various grid operation modes, the ratio of nodes to be connected that are worse than before connection is calculated. When the predicted transformer or line N-1 ratio does not meet N-1, the calculation method is as follows:

[0079]

[0080] In formula (3), n is the number of transformers or lines, k is i is the N-1 changes of the ith transformer / line. i The value selection rule is: considering m (m>=1) operating modes, if the number of operating modes that do not meet N-1 after the transformer / line is connected is greater (deteriorated) than before the connection, then the k of this transformer / line is i Count 1, if they are the same before and after access, count 0, if the operating mode that does not satisfy N-1 before is reduced (improved), count -1.

[0081] The predicted line load rate in the above mentioned method considers m (m>=1) kinds of operation modes. According to the fluctuation characteristics of load and interference source, the time series or random fundamental wave power flow simulation is performed before and after the connection. The average load rate of each transformer / line is calculated based on the results of multiple power flow calculations, and it is judged whether it is full or overloaded. The proportion of transformers or lines whose load rate is worse than before the connection is calculated as follows (4):

[0082]

[0083] In formula (4), k i is the load rate change of the i-th transformer / line. i The value selection rule is: if the number of overload / underload operation modes of this transformer / line after connection is greater (worse) than before connection, then the k of this transformer / line i 1 is counted; if the conditions before and after connection are the same, 0 is counted; if the overload / light load operation mode decreases (improves) compared to the previous one, -1 is counted.

[0084] The predicted short-circuit current mentioned above is the predicted short-circuit current of each line in the distribution network area to be tested, and only considers the operation mode in which the interference source access has the most serious impact on the short-circuit current of the power grid. The calculation method of this indicator is as follows:

[0085]

[0086] In formula (5), n sc is the number of short-circuit current calculation nodes, N sc_a is the number of nodes where the short-circuit current exceeds 95% of the switch interruption capacity after the interference source is connected; N sc_b It is the number of nodes that exceed 95% of the interrupting capacity before access. Therefore, if the number of nodes with excessive short-circuit current increases, Ksc is a positive value. If the number is the same before and after access, it is 0. If the number of nodes with excessive short-circuit current decreases (improves) compared to before, Ksc is a negative value. Ksc is the predicted change ratio of nodes with excessive short-circuit current for each line in the distribution network area to be tested.

[0087] The predicted voltage deviation mentioned above only considers the operation mode in which the interference source access has the most serious impact on the grid voltage deviation. First, according to the fluctuation characteristics of the load and the interference source, the timing or random fundamental wave power flow simulation is performed before and after the access, and the 99% value of the voltage deviation of each node before and after the access is calculated to determine whether it exceeds the standard. According to the change of the exceeding standard before and after the interference source access, the calculation index is as follows (6):

[0088]

[0089] In formula (6), n NOD is the predicted number of regional nodes, N δU_aN is the number of nodes whose voltage deviation 99% value exceeds the standard after the interference source is connected; δU_b is the number of nodes whose voltage deviation 99% value exceeds the standard before access. Therefore, if the number of nodes whose voltage deviation exceeds the standard increases after the interference source is connected, K δU is a positive value. If the number of nodes before and after access is the same, it is counted as 0. If the number of nodes exceeding the standard decreases (improves) compared to before, K δU is a negative value, K δU It is the ratio of voltage deviation exceeding the standard before and after the interference source is connected.

[0090] The predicted harmonic current mentioned above only considers the operation mode in which the interference source has the most serious impact on the harmonic current of the power grid. The sequential or random harmonic power flow simulation is performed before and after the connection to calculate the 95% value of each harmonic current of each branch before and after the connection to determine whether it exceeds the standard. If a harmonic current exceeds the standard, it is counted as a harmonic current exceeding the standard. According to the change of exceeding the standard before and after the interference source is connected, the calculation index is as follows (7):

[0091]

[0092] n L is the number of branches, N Ih_a N is the number of branches where the harmonic current exceeds the standard after the interference source to be connected is connected; Ih_b It is the number of branches with excessive harmonic current before connection.

[0093] The predicted harmonic voltage mentioned above only considers the operation mode in which the interference source has the most serious impact on the harmonic voltage of the power grid. Sequential or random harmonic power flow simulation is performed before and after the connection, and the 95% value of each voltage content rate and the 95% value of the total distortion rate of the harmonic voltage of each node before and after the connection are calculated to determine whether they exceed the standard. If a harmonic voltage exceeds the standard or the total distortion rate exceeds the standard, it is counted as a harmonic voltage exceeding the standard. According to the change of exceeding the standard before and after the interference source is connected, the calculation index is as follows (8):

[0094]

[0095] In formula (8), n NOD is the number of nodes to be predicted, N Uh_a is the number of nodes where the harmonic voltage exceeds the standard after the interference source is connected; N Uh_b It is the number of nodes where the harmonic voltage exceeds the standard before connection.

[0096] The above prediction of three-phase imbalance only considers the operation mode in which the interference source has the most serious impact on the three-phase voltage imbalance of the power grid. The timing or random fundamental wave power flow simulation is performed before and after the connection, and the 95% value and the maximum value of the three-phase voltage imbalance of each node before and after the connection are calculated and compared with the limit values ​​of 2% and 4% respectively. If one of the two exceeds the standard, it is judged to be exceeded. According to the change of the exceeding standard before and after the interference source is connected, the calculation index is as follows (9):

[0097]

[0098] In formula (9), n NOD is the number of nodes, N εU2_a N is the number of nodes where the three-phase voltage imbalance exceeds the standard after the interference source is connected; εU2_b It is the number of nodes whose three-phase voltage imbalance exceeds the standard before access.

[0099] The predicted voltage fluctuation mentioned above only considers the operation mode in which the interference source has the most serious impact on the grid voltage fluctuation. According to the short-term fluctuation characteristics of the load and the interference source, the power flow at the adjacent time when the maximum fluctuation occurs is calculated before and after the interference source is connected, so as to calculate the voltage fluctuation value of each node before and after the interference source is connected, and judge whether it exceeds the standard. According to the change of exceeding the standard before and after the interference source is connected, the calculation index is as follows (10):

[0100]

[0101] In formula (10), n NOD is the predicted number of regional nodes, N d_a is the number of nodes whose voltage fluctuation exceeds the standard after the interference source is connected; N d_b It is the number of nodes whose voltage fluctuation exceeds the standard before access.

[0102] In the above prediction of line loss rate, m (m ≥ 1) operating modes are considered. According to the fluctuation characteristics of load and interference source, time series or random fundamental wave power flow simulation is performed before and after access. The average line loss rate of all lines in the area under various operating modes is calculated based on the results of multiple power flow calculations. The change of line loss rate before and after the interference source is connected is judged. The index is calculated as follows (11):

[0103] K LS =LS a -LS b ; (11)

[0104] (11) Where: LS a is the line loss rate after access, LS b is the line loss rate before access. If the line loss rate increases after access, then K LSIt is a positive value. If the line loss rate before and after access is equal, it is counted as 0. If the line loss rate is reduced (improved) relative to the previous value, K LS is a negative value, K LS is the predicted line loss rate change value.

[0105] When photovoltaic power generation is used as an interference source, due to the limitation of the inverter overcurrent capacity, its short-circuit current generally does not exceed 150% of its rated current. The voltage fluctuation calculation method is to first set the photovoltaic power generation power to the rated power for calculation in the power flow calculation at the same time, and then reduce the photovoltaic power generation power by 50% and calculate again. The relative change value of the voltage amplitude of the node to be connected obtained from the two calculations is used as the voltage fluctuation value.

[0106] The step S13 of calculating the total index score of each access scheme under the capacity to be accessed corresponding to each node to be accessed based on the prediction index parameters of the acceptance capacity of multiple types of interference sources through the power flow calculates the total index score of each access scheme through the following formulas (12)-(13):

[0107] m i =-100h i ; (12);

[0108]

[0109] Among them, hi is the predicted value of each indicator in the area where the interference source to be connected is located, mi is the predicted value of the indicator after calculation and conversion, and w i is the weight of the ith indicator, and M is the total predicted evaluation value.

[0110] For example: perform 24-hour sequence power flow and short-circuit current calculations to obtain the safety indicators, quality indicators, and economic indicators of the distribution network to be tested under the current predicted power supply capacity, and perform indicator aggregation to obtain the total indicator score of each interference source access plan.

[0111] After calculating each indicator, the total score is calculated using weighting. The weights of each indicator used in this case are shown in Table 1.

[0112] Table 1

[0113] Single indicator Weight Single indicator Weight Predicted route N-1 ratio 0.15 Predicting harmonic currents 0.025 Predicted line load factor 0.15 Predicting harmonic voltage 0.025 Predicting short circuit current 0.15 Predicting three-phase unbalance 0.05 Predicted voltage deviation 0.1 Predicting voltage fluctuations 0.025 Predicted line loss rate 0.025

[0114] For the capacity to be accessed corresponding to each node to be accessed in step S12 under the current total access capacity of the interference source, that is, each interference source access plan, the predicted scores of various indicators of the power grid are calculated through power flow calculation, and all indicators are weighted and summed according to the indicator weights to obtain the overall predicted score of each interference source access plan, and the maximum value of all access plan scores is taken as the predicted result of the current total access capacity of the interference source.

[0115] Specifically, in step S12, for each interference source access scheme in step S12 under the current predicted power supply capacity, based on the interference source power and power quality emission characteristics, timing or random fundamental wave, harmonic flow and short circuit calculations are performed, and after the calculation results of various indicators are obtained, the total score is obtained by weighted calculation according to formulas (12)-(13) in step S13.

[0116] For the above formula (13), in the weighted calculation, if one indicator is less than or equal to 0, the minimum value of all indicator scores is taken (that is, if m<0 corresponding to any indicator, access is not allowed). If the scores of single indicators are all 0 points or above, the weighted sum is taken to reflect the average level of each indicator, that is, M is the current indicator score, and the absolute value of M reflects the rationality of the interference source access plan. The larger the absolute value, the more acceptable the interference source access plan. In addition, for larger distribution network power supply areas, a comprehensive prediction method of hierarchical partition aggregation can be adopted. First, the comprehensive index of the partition is calculated, and then the index of each partition under the same voltage level is aggregated, and the index of each voltage level under the region is aggregated. The maximum score of each plan is taken as the prediction result under the current total access capacity of the interference source.

[0117] Step S14: Determine a first access capacity and a second access capacity according to the total indicator score of each access solution, wherein the second access capacity is greater than the first access capacity.

[0118] In one implementation, the first access capacity and the second access capacity are determined according to the total index score of each access solution, and the second access capacity is greater than the first access capacity. Specifically, step S14 includes:

[0119] Step 1: If the total index score of any access scheme is greater than or equal to zero, the total access capacity of the current interference source is set as the first access capacity.

[0120] Step 2: If the total index score of all access solutions is less than zero, the total access capacity of the current interference source is set to the second access capacity.

[0121] For example: determine whether the total index score corresponding to any interference source access plan under the current interference source total access capacity is greater than or equal to 0. If so, set the current interference source total access capacity as the new minimum access capacity; if not, set the current interference source total access capacity as the new maximum access capacity.

[0122] Step S15: Calculate the difference between the second access capacity and the first access capacity, and when the difference is greater than or equal to the preset threshold, return to step S11; when the difference is less than the preset threshold, use the first access capacity as the prediction result of the interference source acceptance capacity.

[0123] Specifically, the above steps S11 to S15 are iterated, and the first access capacity (new minimum access capacity) and the second access capacity (new maximum access capacity) are updated each time to determine whether the difference between the second access capacity and the first access capacity is less than a preset threshold. If not, return to step S11 to continue iterative calculation; if so, the currently predicted first access capacity is used as the final accessible capacity result and the distribution network interference source acceptance capacity, and the scheme with a corresponding total score of a certain indicator greater than or equal to 0 under the first access capacity is used as the recommended access scheme.

[0124] After iterating the calculations of the above steps S11 to S15, the photovoltaic acceptance capacity prediction result of the 10kV voltage level of the distribution network to be tested in this embodiment is 5310kW, and the corresponding optimal photovoltaic access plan is also obtained at the same time. After the acceptance capacity of the medium-voltage sub-grid is predicted, the acceptance capacity of each low-voltage sub-grid is evaluated. The prediction process is similar and will not be repeated here.

[0125] The prediction method of the power quality interference source acceptance capacity in the embodiment of the present invention can accurately predict the total carrying capacity of interference sources accepted by multiple different access nodes to be tested in a large-scale distribution network through the above steps S11-S15. And considering the timing and fluctuation characteristics of different interference sources, based on the combination of random point distribution and binary search method, the optimal point distribution scheme of the distribution network interference source carrying capacity and the power quality interference source access capacity constrained by the power quality level can be finally determined, providing an effective means for the prediction and planning of power quality interference sources such as distributed power sources and electric vehicles in the distribution network.

[0126] Based on the same concept, the embodiment of the present invention also discloses a prediction device for the acceptance capability of power quality interference sources, such as Figure 4 As shown, it includes the following modules:

[0127] The node determination module 41 is used to determine a plurality of nodes to be connected to the interference source based on the total access capacity of the current interference source in the distribution network area to be tested.

[0128] The solution determination module 42 is used to determine the to-be-accessed capacity corresponding to each to-be-accessed node according to the total access capacity of the current interference source and a plurality of to-be-accessed nodes.

[0129] The index calculation module 43 is used to calculate the total index score of the to-be-accessed capacity corresponding to each to-be-accessed node through power flow based on multiple types of interference source acceptance capacity prediction index parameters.

[0130] The capacity determination module 44 is used to determine a first access capacity and a second access capacity according to the total indicator score of each access solution, and the second access capacity is greater than the first access capacity.

[0131] The result determination module 45 is used to calculate the difference between the second access capacity and the first access capacity, and when the difference is greater than or equal to the preset threshold, return to the node determination module, when the difference is less than the preset threshold, use the first access capacity as the prediction result of the interference source acceptance capacity.

[0132] In one implementation, the device for predicting the power quality interference source acceptance capability in the embodiment of the present invention is Figure 4 In the embodiment, the node determination module 41 includes:

[0133] The capacity acquisition submodule 410 is used to obtain the total access capacity of the current interference source in the distribution network area to be tested;

[0134] The capacity determination submodule 411 is used to determine a third access capacity and a fourth access capacity of any node to be accessed in the distribution network area to be tested, wherein the fourth access capacity is greater than the third access capacity;

[0135] The node quantity calculation submodule 412 is used to calculate the upper limit access node quantity and the lower limit access node quantity of the interference source in the distribution network area to be tested according to the third access capacity, the fourth access capacity and the total access capacity of the current interference source;

[0136] The node number generating submodule 413 is used to randomly generate an integer value between the upper limit access node number and the lower limit access node number as the access node number;

[0137] The node determination submodule 414 is used to randomly determine a plurality of nodes to be accessed in the distribution network area to be tested according to the number of access nodes, and randomly determine a plurality of nodes to be accessed in integer values.

[0138] In one embodiment, in the prediction device for the power quality interference source acceptance capacity in the embodiment of the present invention, the node quantity calculation submodule 412 calculates the upper limit access node quantity and the lower limit access node quantity of the interference source in the distribution network area to be tested according to the third access capacity, the fourth access capacity and the total access capacity of the current interference source by using the above formula (1).

[0139] In one embodiment, in the prediction device for the acceptance capacity of power quality interference sources in the embodiment of the present invention, the scheme determination module 42 determines the capacity to be connected corresponding to each node to be connected according to the total access capacity of the current interference source and multiple nodes to be connected by the above formula (2).

[0140] In one embodiment, the prediction device for the acceptance capacity of power quality interference sources in the embodiment of the present invention, the index calculation module 43, is based on multiple types of interference source acceptance capacity prediction index parameters, and calculates the total index score of the capacity to be connected corresponding to each node to be connected through the flow through the above formulas (12)-(13).

[0141] In one implementation, the device for predicting the power quality interference source acceptance capability in the embodiment of the present invention is Figure 4 In the embodiment, the capacity determination module 44 includes:

[0142] The first capacity setting submodule 440 is configured to set the total access capacity of the current interference source to the first access capacity if the total indicator score of any access scheme is greater than or equal to zero.

[0143] The second capacity setting submodule 441 is configured to set the total access capacity of the current interference source to the second access capacity if the total index score of all access solutions is less than zero.

[0144] In one embodiment, the prediction device for power quality interference source acceptance capacity in the embodiment of the present invention, multiple types of interference source acceptance capacity prediction index parameters include: predicted line N-1 ratio, predicted line load rate, predicted short-circuit current, predicted voltage deviation, predicted harmonic current, predicted harmonic voltage, predicted three-phase imbalance, predicted voltage fluctuation, predicted line loss rate. For details, please refer to the above formulas (3)-(11).

[0145] The device for predicting the acceptance capacity of power quality interference sources in the embodiment of the present invention can accurately predict the total carrying capacity of interference sources accepted by multiple different access nodes to be tested in a large-scale distribution network.

[0146] Based on the same concept, the embodiment of the present invention also discloses an electronic device, such as Figure 5 As shown, the electronic device may include a processor 51 and a memory 52, wherein the processor 51 and the memory 52 may be connected via a bus or other means. Figure 5 The example of connecting through bus is taken in the following.

[0147] The processor 51 may be a central processing unit (CPU). The processor 51 may also be other general-purpose processors, digital signal processors (DSP), application-specific integrated circuits (ASIC), field-programmable gate arrays (FPGA) or other programmable logic devices, discrete gate or transistor logic devices, discrete hardware components, or a combination of the above chips.

[0148] The memory 52 is a non-transient computer-readable storage medium that can be used to store non-transient software programs, non-transient computer executable programs and modules. The processor 51 executes various functional applications and data processing of the processor by running the non-transient software programs, instructions and modules stored in the memory 52, that is, the prediction method of the power quality interference source acceptance capability in the above method embodiment is realized.

[0149] The memory 52 may include a program storage area and a data storage area, wherein the program storage area may store an operating system and applications required for at least one function; the data storage area may store data created by the processor 51, etc. In addition, the memory 52 may include a high-speed random access memory, and may also include a non-volatile memory, such as at least one disk storage device, a flash memory device, or other non-volatile solid-state storage devices. In some embodiments, the memory 52 may optionally include a memory remotely arranged relative to the processor 51, and these remote memories may be connected to the processor 51 via a network. Examples of the above-mentioned network include, but are not limited to, a power grid, the Internet, an intranet, a local area network, a mobile communication network, and combinations thereof.

[0150] One or more modules are stored in the memory 52, and when executed by the processor 51, the method for predicting the power quality interference source acceptance capability in the embodiment shown in the drawings is executed.

[0151] For details of the above electronic equipment, please refer to Figures 1 to 5 The corresponding related descriptions and effects in the illustrated embodiments can be understood and will not be repeated here.

[0152] Those skilled in the art can understand that all or part of the processes in the above-mentioned embodiments can be implemented by instructing the relevant hardware through a computer program, and the program can be stored in a computer-readable storage medium. When the program is executed, it can include the processes of the embodiments of the above-mentioned methods. Among them, the storage medium can be a disk, an optical disk, a read-only memory (ROM), a random access memory (RAM), a flash memory, a hard disk drive (HDD) or a solid-state drive (SSD), etc.; the storage medium can also include a combination of the above-mentioned types of memory.

[0153] Obviously, the above embodiments are merely examples for the purpose of clear explanation, and are not intended to limit the implementation methods. For those skilled in the art, other different forms of changes or modifications can be made based on the above description. It is not necessary and impossible to list all the implementation methods here. The obvious changes or modifications derived therefrom are still within the scope of protection of the invention.

Claims

1. A method for predicting the acceptance capability of power quality interference sources, characterized in that: The steps include: Step S11: in the distribution network area to be tested, a plurality of nodes to be connected to the interference source to be connected are determined based on the total access capacity of the current interference source; including: Obtaining the total access capacity of the current interference sources in the distribution network area to be tested; Determine a third access capacity and a fourth access capacity of any node to be accessed in the distribution network area to be tested, wherein the fourth access capacity is greater than the third access capacity; the third access capacity is the lower access capacity or the minimum access capacity of any node to be accessed i; the fourth access capacity is the upper access capacity or the maximum access capacity of any node to be accessed i; According to the third access capacity, the fourth access capacity and the total access capacity of the current interference source, the upper limit access node number and the lower limit access node number of the interference source in the distribution network area to be tested are calculated; the upper limit access node number and the lower limit access node number of the interference source in the distribution network area to be tested are calculated by the following formula: N max =min{S total / S min ,N total } N min =ceil{S total / S max }; Among them, S total is the total access capacity of the current interference source, N max is the upper limit number of access nodes, N min is the lower limit number of access nodes, N total is the total number of nodes in the distribution network area to be tested, S max is the fourth access capacity, S min is the third access capacity; According to the upper limit of the number of access nodes and the lower limit of the number of access nodes, randomly generate an integer value between the two as the number of access nodes; According to the number of access nodes, a plurality of nodes to be accessed are randomly determined in the distribution network area to be tested; Step S12: determining the to-be-accessed capacity corresponding to each to-be-accessed node according to the total access capacity of the current interference source and the plurality of to-be-accessed nodes; The capacity to be connected corresponding to each node to be connected is determined by the following formula: Among them, S total is the total access capacity of the current interference source, S R is the current remaining access capacity, S ub is the upper limit access capacity of the node i to be accessed, S lb is the lower limit access capacity of the node i to be accessed, S i is the capacity of the node i to be connected, S i For S ub With S lb Any random value between S min An integer multiple of ; Step S13: Based on multiple types of interference source acceptance capacity prediction index parameters, the total index score of each access scheme under the access capacity corresponding to each of the access nodes is calculated through power flow; The total index score of each access scheme under the capacity to be accessed corresponding to each node to be accessed is calculated by the following formula: m i =-100h i ; Wherein, hi is the predicted value of each index after the distribution network area to be tested is connected to the interference source according to any access scheme, mi is the predicted value of the index after calculation and conversion, and w i is the weight of the i-th indicator, and M is the total prediction evaluation value; Step S14: determining a first access capacity and a second access capacity according to the total index score of each access solution, wherein the second access capacity is greater than the first access capacity, including: If the total index score of any access scheme is greater than or equal to zero, setting the total access capacity of the current interference source to the first access capacity; If the total index score of all access solutions is less than zero, setting the total access capacity of the current interference source to the second access capacity; Step S15: Calculate the difference between the second access capacity and the first access capacity, and when the difference is greater than or equal to a preset threshold, return to step S11; when the difference is less than the preset threshold, use the first access capacity as a predicted result of the interference source acceptance capacity.

2. The method for predicting the power quality interference source acceptance capability according to claim 1, characterized in that: The various types of interference source acceptance capacity prediction index parameters include: predicted line N-1 ratio, predicted line load rate, predicted short-circuit current, predicted voltage deviation, predicted harmonic current, predicted harmonic voltage, predicted three-phase imbalance, predicted voltage fluctuation, and predicted line loss rate.

3. A device for predicting the acceptance capacity of power quality interference sources, characterized in that: Includes the following modules: A node determination module is used to determine multiple nodes to be connected to the interference source based on the total access capacity of the current interference source in the distribution network area to be tested; including: Obtaining the total access capacity of the current interference sources in the distribution network area to be tested; Determine a third access capacity and a fourth access capacity of any node to be accessed in the distribution network area to be tested, wherein the fourth access capacity is greater than the third access capacity; the third access capacity is the lower access capacity or the minimum access capacity of any node to be accessed i; the fourth access capacity is the upper access capacity or the maximum access capacity of any node to be accessed i; According to the third access capacity, the fourth access capacity and the total access capacity of the current interference source, the upper limit access node number and the lower limit access node number of the interference source in the distribution network area to be tested are calculated; the upper limit access node number and the lower limit access node number of the interference source in the distribution network area to be tested are calculated by the following formula: N max =min{S total / S min ,N total } N min =ceil{S total / S max }; Among them, S total is the total access capacity of the current interference source, N max is the upper limit number of access nodes, N min is the lower limit number of access nodes, N total is the total number of nodes in the distribution network area to be tested, S max is the fourth access capacity, S min is the third access capacity; According to the upper limit of the number of access nodes and the lower limit of the number of access nodes, randomly generate an integer value between the two as the number of access nodes; According to the number of access nodes, a plurality of nodes to be accessed are randomly determined in the distribution network area to be tested; A scheme determination module, used to determine the to-be-accessed capacity corresponding to each to-be-accessed node according to the total access capacity of the current interference source and the multiple to-be-accessed nodes; The capacity to be connected corresponding to each node to be connected is determined by the following formula: Among them, S total is the total access capacity of the current interference source, S R is the current remaining access capacity, S ub is the upper limit access capacity of the node i to be accessed, S lb is the lower limit access capacity of the node i to be accessed, S i is the capacity of the node i to be connected, S i For S ub With S lb Any random value between S min An integer multiple of ; An index calculation module, used to calculate the total index score of each access scheme under the to-be-accessed capacity corresponding to each to-be-accessed node through power flow based on multiple types of interference source acceptance capacity prediction index parameters; The total index score of each access scheme under the capacity to be accessed corresponding to each node to be accessed is calculated by the following formula: m i =-100h i ; Wherein, hi is the predicted value of each index after the distribution network area to be tested is connected to the interference source according to any access scheme, mi is the predicted value of the index after calculation and conversion, and w i is the weight of the i-th indicator, and M is the total prediction evaluation value; A capacity determination module, configured to determine a first access capacity and a second access capacity according to the total indicator score of each access scheme, wherein the second access capacity is greater than the first access capacity, comprising: If the total index score of any access scheme is greater than or equal to zero, setting the total access capacity of the current interference source to the first access capacity; If the total index score of all access solutions is less than zero, setting the total access capacity of the current interference source to the second access capacity; The result determination module is used to calculate the difference between the second access capacity and the first access capacity, and when the difference is greater than or equal to a preset threshold, return to the node determination module; when the difference is less than the preset threshold, use the first access capacity as the prediction result of the interference source acceptance capacity.

4. A computer-readable storage medium, characterized in that: The computer-readable storage medium stores computer instructions, and the computer instructions are used to enable the computer to execute the method for predicting the power quality interference source acceptance capability of claim 1.

5. An electronic device, characterized in that: include: A memory and a processor, wherein the memory and the processor are communicatively connected to each other, the memory stores computer instructions, and the processor executes the method for predicting the power quality interference source acceptance capacity as described in claim 1 by executing the computer instructions.

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