Active distribution network closed-loop control method, device and electronic equipment

Abstract

The present invention belongs to the field of active distribution networks, and provides an active distribution network closed-loop control method, device and electronic device. The method includes: obtaining the operation data and load data of distributed power sources; performing Latin hypercube sampling to obtain photovoltaic semi-invariants and load semi-invariants; performing matrix transformation and series expansion on the photovoltaic semi-invariants and load semi-invariants to obtain the cumulative distribution function and probability density function of the closed-loop current; obtaining the key current data of the feeders on both sides of the closed-loop point under different closed-loop operation strategies, and inputting the key current data into the cumulative distribution function and probability density function to obtain the safety evaluation index value; taking the closed-loop operation strategy with the optimal safety evaluation index value as the target closed-loop operation strategy, and performing closed-loop control on the active distribution network according to the target closed-loop operation strategy. By determining the safety evaluation index value of each closed-loop operation strategy through Latin hypercube sampling and series expansion, the safety and reliability of the closed-loop process are improved.

Description

Technical Field

[0001] The present invention relates to the technical field of active distribution networks, and in particular, to a method, device, and electronic device for closed-loop control of an active distribution network. Background Art

[0002] An active distribution network refers to a distribution network that includes distributed power sources. In addition to distributed power sources, an active distribution network also includes distribution lines, distribution transformers, various switching devices, reactive power compensation devices, and intelligent meters, communication devices, and control systems for monitoring and control. When a fault occurs in the distribution line of an active distribution network and needs to be processed, or when maintenance work is carried out according to a plan, the closed-loop operation is an effective countermeasure, which can achieve load transfer without interrupting power supply and minimize the impact on user power consumption.

[0003] In the related art, during the closed-loop process, since steady-state circulating current and impact current are very likely to be generated, these abnormal current conditions may cause misoperation of protection devices and lead to overloading of distribution lines, thereby posing a serious threat to the safe and stable operation of the entire power system. At the same time, when performing closed-loop related calculations, traditional analysis schemes based on deterministic parameters and relatively stable operating conditions are difficult to effectively evaluate the safety of the closed-loop process, and thus it is easy to have problems of low safety and insufficient reliability in closed-loop control. Summary of the Invention

[0004] The present invention provides a method, device, and electronic device for closed-loop control of an active distribution network to solve the defects of low safety and insufficient reliability of traditional closed-loop control schemes.

[0005] On the one hand, the present invention provides a method for closed-loop control of an active distribution network, including:

[0006] Obtaining the operation data and load data of distributed power sources in the closed-loop network topology of the active distribution network;

[0007] Performing Latin hypercube sampling on the operation data and load data of the distributed power sources to obtain photovoltaic semi-invariants and load semi-invariants;

[0008] Performing matrix transformation and series expansion on the photovoltaic semi-invariants and the load semi-invariants to obtain the cumulative distribution function and probability density function of the closed-loop current;

[0009] Obtaining the key current data of the feeders on both sides of the closed-loop point under different closed-loop operation strategies, and inputting the key current data into the cumulative distribution function and the probability density function to obtain the safety evaluation index values corresponding to each closed-loop operation strategy;

[0010] Take the closed-loop operation strategy with the optimal safety evaluation index value as the target closed-loop operation strategy, and perform closed-loop control on the active distribution network according to the target closed-loop operation strategy.

[0011] According to the active distribution network closed-loop control method provided by the present invention, perform matrix transformation and series expansion on the photovoltaic semi-invariant and the load semi-invariant to obtain the cumulative distribution function and probability density of the closed-loop current, including:

[0012] Based on the operation data of the distributed power source and the load data, perform network power flow calculation at the reference operating point to obtain the power flow calculation result;

[0013] Add the photovoltaic semi-invariant and the load semi-invariant, and calculate the cumulative amount of node injection power;

[0014] Based on the power flow calculation result, perform matrix transformation on the cumulative amount of node injection power to calculate the semi-invariant of the closed-loop current;

[0015] Perform series expansion on the semi-invariant of the closed-loop current, and fit to obtain the cumulative distribution function and probability density function of the closed-loop current.

[0016] According to the active distribution network closed-loop control method provided by the present invention, input the key current data into the cumulative distribution function and the probability density function to obtain the safety evaluation index value corresponding to each closed-loop operation strategy, including:

[0017] Input the first key sub-data in the key current data into the cumulative distribution function, and calculate the preliminary closed-loop success rate according to the function output value;

[0018] When the preliminary closed-loop success rate is higher than the preset success rate threshold, input the second key sub-data in the key current data under each closed-loop operation strategy into the probability density function, and calculate the maximum over-limit rate and average over-line rate of the closed-loop current;

[0019] Take the preliminary closed-loop success rate, the maximum over-limit rate, and the average over-line rate as the safety evaluation index value corresponding to each closed-loop operation strategy.

[0020] According to the active distribution network closed-loop control method provided by the present invention, the first key sub-data includes: the first maximum current-carrying capacity, the second maximum current-carrying capacity, the first instantaneous current protection setting value, and the second instantaneous current protection setting value of the feeders on both sides of the closed-loop point;

[0021] The second key sub-data includes: the closed-loop current and the preset rated current;

[0022] The cumulative distribution function includes: a first cumulative distribution sub-function corresponding to the first closed-loop steady-state current of the feeders on both sides of the closed-loop point, a second cumulative distribution sub-function corresponding to the second closed-loop steady-state current, a third cumulative distribution sub-function corresponding to the first closed-loop transient current, and a fourth cumulative distribution sub-function corresponding to the second closed-loop transient current.

[0023] According to the active distribution network closed-loop control method provided by the present invention, inputting the first key sub-data in the key current data into the cumulative distribution function, and calculating the preliminary closed-loop success rate according to the function output value, including:

[0024] Inputting the first maximum current-carrying capacity into the first cumulative distribution sub-function to obtain a first function output value;

[0025] Inputting the second maximum current-carrying capacity into the second cumulative distribution sub-function to obtain a second function output value;

[0026] Inputting the first instantaneous overcurrent protection setting value into the third cumulative distribution sub-function to obtain a third function output value;

[0027] Inputting the second instantaneous overcurrent protection setting value into the fourth cumulative distribution sub-function to obtain a fourth function output value;

[0028] Integrating the first function output value, the second function output value, the third function output value, and the fourth function output value to calculate the preliminary closed-loop success rate.

[0029] According to the active distribution network closed-loop control method provided by the present invention, the closed-loop operation strategy with the optimal safety evaluation index value is determined through the following process:

[0030] Selecting alternative closed-loop strategies from all closed-loop operation strategies according to preset screening conditions; wherein, the preset screening conditions include: the preliminary closed-loop success rate is higher than a preset success rate threshold, and both the maximum overlimit rate and the average overline rate are lower than their respective overline rate thresholds;

[0031] Performing a weighted operation on the preliminary closed-loop success rate, the maximum overlimit rate, and the average overline rate to calculate the comprehensive evaluation value of each alternative closed-loop strategy;

[0032] Taking the alternative closed-loop strategy with the highest comprehensive evaluation value as the closed-loop operation strategy with the optimal safety evaluation index value.

[0033] According to the active distribution network closed-loop control method provided by the present invention, after performing closed-loop control on the active distribution network according to the target closed-loop operation strategy, the method further includes:

[0034] Obtaining the branch current of each power supply branch in the active distribution network after closing the loop;

[0035] Determine whether the branch current of each power supply branch is higher than a preset first current upper limit value to obtain a first determination result;

[0036] If the first determination result is yes, determine the power supply branch with a branch current higher than the first current upper limit value as the first target branch, and adjust the output power of the distributed power source on the first target branch to a first power setting value;

[0037] If the first determination result is no, determine whether the branch current of each power supply branch is higher than a preset second current upper limit value to obtain a second determination result;

[0038] If the second determination result is yes, determine the power supply branch with a branch current higher than the second current upper limit value as the second target branch, and adjust the output power of the distributed power source on the second target branch to a second power setting value;

[0039] Wherein, the first current upper limit value is higher than the second current upper limit value.

[0040] According to the active distribution network closed-loop control method provided by the present invention, adjusting the output power of the distributed power source on the first target branch to the first power setting value includes:

[0041] Subtract the branch current of the first target branch from the first current upper limit value to obtain a current overlimit value;

[0042] If the current overlimit value satisfies a first preset overlimit interval, adjust the output power of the distributed power source on the first target branch to the first power setting value according to a preset first power adjustment curve;

[0043] If the current overlimit value satisfies a second preset overlimit interval, adjust the output power of the distributed power source on the first target branch to the first power setting value according to a preset second power adjustment curve;

[0044] Wherein, the upper limit value of the first preset overlimit interval is less than the upper limit value of the second preset overlimit interval; the average slope of the first power adjustment curve is less than the average slope of the second power adjustment curve.

[0045] On the other hand, the present invention also provides an active distribution network closed-loop control device, including:

[0046] An acquisition module for acquiring the operation data and load data of the distributed power source in the closed-loop network topology of the active distribution network;

[0047] A sampling module, configured to perform Latin hypercube sampling on the operation data and load data of the distributed power source to obtain photovoltaic semi-invariants and load semi-invariants;

[0048] A transformation module, configured to perform matrix transformation and series expansion on the photovoltaic semi-invariants and the load semi-invariants to obtain the cumulative distribution function and probability density function of the closed-loop current;

[0049] An evaluation module, configured to obtain the key current data of the feeders on both sides of the closed-loop point under different closed-loop operation strategies, and input the key current data into the cumulative distribution function and the probability density function to obtain the safety evaluation index values corresponding to each closed-loop operation strategy;

[0050] A control module, configured to use the closed-loop operation strategy with the optimal safety evaluation index value as the target closed-loop operation strategy, and perform closed-loop control on the active distribution network according to the target closed-loop operation strategy.

[0051] On the other hand, the present invention further provides an electronic device, including a memory, a processor, and a computer program stored on the memory and executable on the processor. When the processor executes the program, it implements the closed-loop control method for the active distribution network as described in any one of the above.

[0052] The closed-loop control method, device, and electronic device for the active distribution network provided by the present invention obtain photovoltaic semi-invariants and load semi-invariants by performing Latin hypercube sampling on the operation data and load data of the distributed power source; perform matrix transformation and series expansion on the photovoltaic semi-invariants and load semi-invariants to obtain the cumulative distribution function and probability density function of the closed-loop current; obtain the key current data of the feeders on both sides of the closed-loop point under different closed-loop operation strategies, and input the key current data into the cumulative distribution function and probability density function to obtain the safety evaluation index values corresponding to each closed-loop operation strategy; use the closed-loop operation strategy with the optimal safety evaluation index value as the target closed-loop operation strategy, and perform closed-loop control on the active distribution network according to the target closed-loop operation strategy. Since the safety evaluation index values of each closed-loop operation strategy are determined by means of Latin hypercube sampling and series expansion during the closed-loop process, the active distribution network can be closed-loop controlled according to the closed-loop operation strategy with the optimal safety evaluation index value, thereby improving the safety and reliability of the closed-loop process. Description of the Drawings

[0053] In order to more clearly illustrate the technical solutions in the present invention or the prior art, the following will briefly introduce the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings in the following description are some embodiments of the present invention. For those of ordinary skill in the art, other drawings can be obtained based on these drawings without creative efforts.

[0054] Figure 1 It is a schematic flowchart of the closed-loop control method for an active distribution network provided by an embodiment of the present invention;

[0055] Figure 2 It is the closed-loop network topology corresponding to an active distribution network with 34 nodes;

[0056] Figure 3 It is about the steady-state closed-loop current in line 26 - 28 I a curve graph;

[0057] Figure 4 It is about the transient closed-loop current in line 26 - 28 I am curve graph;

[0058] Figure 5 It is the error comparison graph between the LHS-GC method and the traditional semi-invariant method;

[0059] Figure 6 It is a schematic structural diagram of the closed-loop control device for an active distribution network provided by an embodiment of the present invention;

[0060] Figure 7 It is a schematic structural diagram of the electronic device provided by an embodiment of the present invention. Detailed implementation manners

[0061] To make the objectives, technical solutions and advantages of the present invention clearer, the technical solutions in the present invention will be clearly and completely described below with reference to the accompanying drawings in the present invention. Apparently, the described embodiments are some but not all of the embodiments of the present invention. All other embodiments obtained by those of ordinary skill in the art without making creative efforts based on the embodiments in the present invention belong to the scope of protection of the present invention.

[0062] This embodiment mainly relates to the field of active distribution networks and can be specifically applied to the closed-loop control link of active distribution networks. With the vigorous development of the national economy, the requirements for power supply reliability in all aspects of social production and life are increasing day by day. As the power supply link directly facing users, the active distribution network usually follows the mode of "closed-loop design and open-loop operation", which aims to ensure the stability of power supply and the convenience of daily operation and maintenance management. When a fault occurs in the distribution line of the active distribution network and needs to be processed, or when maintenance work is carried out according to the plan, the closed-loop power transfer operation is an effective countermeasure, which can achieve load transfer without interrupting power supply and minimize the impact on user power consumption.

[0063] However, the closed-loop power supply operation of the active distribution network is not without risks. The "connect first and then disconnect" method it adopts will change the original distribution network structure and power flow distribution. During the closed-loop process, steady-state circulating current and impact current are very likely to occur. These abnormal current conditions may cause misoperation of protection devices and lead to overload of lines, thus posing a serious threat to the safe and stable operation of the entire power system.

[0064] Among many distributed generation technologies, the photovoltaic power generation system, with its significant advantages such as small scale and easy installation, is increasing its proportion in the active distribution network and gradually playing a crucial role. The solution provided in this embodiment mainly targets the photovoltaic power generation system. However, the power output of the photovoltaic power generation system is greatly affected by environmental factors such as light intensity and weather conditions, showing strong randomness and volatility. This makes the traditional analysis method based on deterministic parameters and relatively stable operating conditions no longer applicable when the active distribution network conducts closed-loop related calculations.

[0065] At the same time, in the traditional closed-loop operation link of the active distribution network, due to the lack of full consideration of the influence of the randomness and volatility of distributed power generation output on the closed-loop current, it is difficult to accurately and comprehensively evaluate the safety of the closed-loop operation and effectively cope with the complex situations faced by the closed-loop operation in the current active distribution network environment with the access of renewable energy such as distributed photovoltaic power sources.

[0066] It can be seen that the traditional closed-loop control scheme of the active distribution network has problems of insufficient safety and reliability.

[0067] In view of the above problems, the embodiments of the present invention provide specific solutions. The following combines Figures 1-7 to describe the detailed solutions of the closed-loop control method, device and electronic equipment for the active distribution network provided by the present invention.

[0068] Figure 1 is a schematic flow chart of the closed-loop control method for the active distribution network provided by the embodiments of the present invention.

[0069] As Figure 1 shown, for the closed-loop control method for the active distribution network provided by the embodiments of the present invention, the execution subject can be a computer or a server with data transceiver and data processing capabilities. This method mainly includes the following steps:

[0070] Step 110: Obtain the operation data and load data of distributed power sources in the closed-loop network topology of the active distribution network.

[0071] It can be understood that the closed-loop network topology is mainly presented as a topology graph including nodes and connections by connecting different distribution lines and distributed power sources in the active distribution network. Figure 2An exemplary loop - closing network topology corresponding to an active distribution network with 34 nodes is shown.

[0072] In this embodiment, the operation data of distributed power sources includes key information such as the output power of distributed power sources, the node positions of distributed power sources in the loop - closing network topology, node connection relationships, and line parameters.

[0073] Load data includes information such as load change rules and load power values at different time periods.

[0074] Step 120: Perform Latin Hypercube Sampling on the operation data of distributed power sources and load data to obtain photovoltaic semi - invariants and load semi - invariants.

[0075] In this embodiment, photovoltaic semi - invariants mainly refer to the cumulants corresponding to the operation data of distributed power sources related to distributed power sources, and load semi - invariants mainly refer to the cumulants corresponding to load data.

[0076] It can be understood that Latin Hypercube Sampling (LHS) is a statistical method for sampling from a multi - dimensional space, which can obtain a better coverage of the variable space with a smaller number of samples, so as to perform uncertainty analysis and model evaluation more efficiently.

[0077] Step 130: Perform matrix transformation and series expansion on the photovoltaic semi - invariants and load semi - invariants to obtain the cumulative distribution function and probability density function of the loop - closing current.

[0078] In this embodiment, by performing matrix transformation on the photovoltaic semi - invariants and load semi - invariants, the semi - invariants of each order of the loop - closing current can be obtained, and then the cumulative distribution function and probability density function of the loop - closing current can be fitted by using series expansion.

[0079] Step 140: Obtain the key current data of the feeders on both sides of the loop - closing point under different loop - closing operation strategies, and input the key current data into the cumulative distribution function and probability density function to obtain the safety evaluation index values corresponding to each loop - closing operation strategy.

[0080] It can be understood that in this embodiment, multiple loop - closing operation strategies with a certain feasibility can be preset in advance, and the key current data during the loop - closing process under different loop - closing operation strategies can be obtained respectively. Then, based on the cumulative distribution function and probability density function, the safety evaluation index values corresponding to different loop - closing operation strategies can be further determined. The safety evaluation index values can characterize the safety of the loop - closing operation strategies.

[0081] Step 150: Take the loop - closing operation strategy with the optimal safety evaluation index value as the target loop - closing operation strategy, and perform loop - closing control on the active distribution network according to the target loop - closing operation strategy.

[0082] In this embodiment, the optimal closed-loop operation strategy is selected by screening the safety evaluation index values, and this is used as the target closed-loop operation strategy for closed-loop control of the active distribution network, thereby ensuring the safety and reliability of the closed-loop link.

[0083] In one embodiment, matrix transformation and series expansion are performed on the photovoltaic semi-invariant and the load semi-invariant to obtain the cumulative distribution function and probability density function of the closed-loop current, which specifically includes:

[0084] In the first step, based on the operation data of distributed power sources and the load data, network power flow calculation is performed at the reference operating point to obtain the power flow calculation results.

[0085] It can be understood that the reference operating point refers to the operating point when the power system is in a normal and typical operating state. Performing network power flow calculation at the reference operating point is an important basis for power system analysis, and its purpose is to determine the voltage amplitude and phase angle of each node in the power system, as well as the power distribution of each branch. In practical applications, the reference operating point is usually determined according to the historical operation data of the system, the planning requirements, and the typical operating mode.

[0086] In practical applications, the network power flow calculation can adopt currently relatively mature power flow calculation strategies, such as the Newton-Raphson method, the fast decoupled method and other common power flow calculation strategies, so as to obtain accurate power flow calculation results.

[0087] In this embodiment, the power flow calculation results may include the Jacobian matrix established based on key information such as the node voltage amplitude, node voltage phase angle, node injection power, branch active power and reactive power, and branch power loss and the coefficient matrix .

[0088] In the second step, the photovoltaic semi-invariant and the load semi-invariant are added together to calculate the cumulative amount of node injection power.

[0089] In this embodiment, through the load semi-invariant and the photovoltaic semi-invariant sum, the cumulative amount of node injection power can be obtained, and the calculation formula is as follows:

[0090] (1)

[0091] In the third step, based on the power flow calculation results, matrix transformation is performed on the cumulative amount of node injection power to calculate the semi-invariant of the closed-loop current.

[0092] In this embodiment, the calculation formula of the semi-invariant of the closed-loop current is specifically as follows:

[0093] (2)

[0094] Among them, represents the semi-invariant of the closed-loop current, represents the coefficient matrix, represents the Jacobian matrix, represents the cumulative amount of node injection power.

[0095] From this, the semi-invariants of each order of the closed-loop current can be obtained, thus providing an effective data basis for the subsequent series expansion step.

[0096] Fourth step, perform series expansion on the semi-invariants of the closed-loop current, and fit to obtain the cumulative distribution function and probability density function of the closed-loop current.

[0097] In some embodiments, the series expansion step can be implemented using the Gram-Charlier series. The Gram-Charlier series can be used to represent the probability density function or cumulative distribution function of a random variable as a power series expansion form based on the normal distribution.

[0098] In this embodiment, it can be set that and are respectively the cumulative distribution basis function and probability density basis function of the standard normal distribution, c i is the semi-invariant of each order of the closed-loop current, and the Gram-Charlier series expression is specifically as follows:

[0099] (3)

[0100] (4)

[0101] Among them, F ( x ) represents the cumulative distribution function, represents the cumulative distribution basis function of the standard normal distribution, represents the probability density function. The cumulative distribution function is the integral of the probability density function, represents the probability density basis function of the standard normal distribution, c i represents the semi-invariant of each order of the closed-loop current, i in the range of the interval [1, k].

[0102] According to the above operations, the cumulative distribution function and probability density function of the closed-loop current can be obtained.

[0103] In one embodiment, key current data is input into the cumulative distribution function and the probability density function to obtain the safety evaluation index values corresponding to each loop closing operation strategy, specifically including:

[0104] First, the first key sub-data in the key current data is input into the cumulative distribution function, and the preliminary loop closing success rate is calculated according to the function output value.

[0105] In one embodiment, the first key sub-data specifically includes: the first maximum carrying capacity, the second maximum carrying capacity, the first instantaneous overcurrent protection setting value, and the second instantaneous overcurrent protection setting value of the feeders on both sides of the loop closing point.

[0106] The cumulative distribution function specifically includes: the first cumulative distribution sub-function corresponding to the first loop closing steady-state current of the feeders on both sides of the loop closing point, the second cumulative distribution sub-function corresponding to the second loop closing steady-state current, the third cumulative distribution sub-function corresponding to the first loop closing transient current, and the fourth cumulative distribution sub-function corresponding to the second loop closing transient current.

[0107] In a specific implementation, inputting the first key sub-data in the key current data into the cumulative distribution function and calculating the preliminary loop closing success rate according to the function output value specifically includes:

[0108] The first step is to input the first maximum carrying capacity into the first cumulative distribution sub-function to obtain the first function output value.

[0109] The second step is to input the second maximum carrying capacity into the second cumulative distribution sub-function to obtain the second function output value.

[0110] The third step is to input the first instantaneous overcurrent protection setting value into the third cumulative distribution sub-function to obtain the third function output value.

[0111] The fourth step is to input the second instantaneous overcurrent protection setting value into the fourth cumulative distribution sub-function to obtain the fourth function output value.

[0112] The fifth step is to integrate the first function output value, the second function output value, the third function output value, and the fourth function output value to calculate the preliminary loop closing success rate.

[0113] In this embodiment, let F 1( x ) be the first cumulative distribution sub-function corresponding to the first loop closing steady-state current of the feeders on both sides of the loop closing point, let F 2( x ) be the second cumulative distribution sub-function corresponding to the second loop closing steady-state current, let F 3( x ) be the third cumulative distribution sub-function corresponding to the first loop closing transient current, let F 4( x) is the fourth cumulative distribution sub-function corresponding to the second loop-closing transient current.

[0114] The first maximum carrying capacity of the feeders on both sides of the loop-closing point is taken respectively as I max.a and the second maximum carrying capacity is I max.b , the setting value of the first instantaneous current protection is I set.a and the setting value of the second instantaneous current protection is I set.b , then the preliminary loop-closing success rate P can be expressed as follows:

[0115] (5)

[0116] where P represents the preliminary loop-closing success rate, F 1( I max.a ) represents the output value of the first function obtained by inputting the first maximum carrying capacity I max.a into the first cumulative distribution sub-function F 1( x ), F 2( I max.b ) represents the output value of the second function obtained by inputting the second maximum carrying capacity I max.b into the second cumulative distribution sub-function F 2( x ), F 3( I set.a ) represents the output value of the third function obtained by inputting the setting value of the first instantaneous current protection I set.a into the third cumulative distribution sub-function F 3( x ), F 4( I set.b ) represents the output value of the fourth function obtained by inputting the setting value of the second instantaneous current protection I set.b into the fourth cumulative distribution sub-function F 4( x ).

[0117] In this embodiment, by multiplying the output values of the four functions, the preliminary loop-closing success rate of each loop-closing operation strategy can be calculated. The preliminary loop-closing success rate can characterize the possibility that the current loop-closing operation strategy can make the active distribution network close the loop successfully.

[0118] Then, when the preliminary loop closing success rate is higher than the preset success rate threshold, the second key sub-data in the key current data under each loop closing operation strategy is input into the probability density function to calculate the maximum overlimit rate and the average overline rate of the loop closing current.

[0119] Specifically, the second key sub-data includes the loop closing current and the preset rated current.

[0120] In this embodiment, the preset success rate threshold can be reasonably set according to actual needs. For example, it can be set to 95%. When the preliminary loop closing success rate is higher than 95%, it indicates that the current loop closing operation strategy makes the preliminary loop closing of the active distribution network successful.

[0121] It can be understood that the loop closing current refers to the current generated in the closed loop due to the differences in parameters such as the voltage amplitude, phase, and frequency of the two power sources at the moment of loop closing during the loop closing operation of the power system. The loop closing steady-state current refers to the current continuously existing in the loop closing loop after a period of transition when the power system enters the stable operation state after the loop closing operation is completed. The loop closing transient current refers to the transient current that appears in the loop closing loop from the moment of loop closing operation to before the system reaches the steady operation state. In practical applications, the loop closing current can be obtained after comprehensively analyzing the loop closing steady-state current and the loop closing transient current.

[0122] In this embodiment, the maximum overlimit rate of the loop closing current and the average overline rate can be respectively expressed as follows:

[0123] (6)

[0124] (7)

[0125] Among them, represents the maximum overlimit rate of the loop closing current, represents the average overline rate of the loop closing current, I F represents the loop closing current, I Lmax represents the preset rated current, represents the probability density function.

[0126] In practical applications, the overlimit rate threshold corresponding to the maximum overlimit rate can be set to 10%, and the overlimit rate threshold corresponding to the average overline rate can be set to 5%.

[0127] Finally, the preliminary loop closing success rate, the maximum overlimit rate, and the average overline rate are used as the safety evaluation index values corresponding to each loop closing operation strategy.

[0128] In one embodiment, the loop closing operation strategy with the optimal safety evaluation index value can be specifically determined through the following process:

[0129] First step, according to the preset screening conditions, select the alternative loop closing strategies from all loop closing operation strategies; wherein, the preset screening conditions include: the initial loop closing success rate is higher than the preset success rate threshold, and both the maximum overlimit rate and the average overline rate are lower than their respective overline rate thresholds.

[0130] Second step, perform weighted operations on the initial loop closing success rate, the maximum overlimit rate, and the average overline rate, and calculate the comprehensive evaluation value of each alternative loop closing strategy.

[0131] It should be noted that in this embodiment, the initial loop closing success rate, the maximum overlimit rate, and the average overline rate are all values between 0 and 1. In practical applications, the initial loop closing success rate, the maximum overlimit rate, and the average overline rate can be normalized so that the values of the three are all distributed between 0 and 1.

[0132] In this embodiment, the comprehensive evaluation value can be specifically expressed as follows:

[0133] (8)

[0134] Wherein, represents the comprehensive evaluation value, represents the initial loop closing success rate is the weight value of represents the maximum overlimit rate is the weight value of represents the average overline rate is the weight value of

[0135] Third step, take the alternative loop closing strategy with the highest comprehensive evaluation value as the loop closing operation strategy with the optimal safety evaluation index value.

[0136] In this embodiment, the comprehensive evaluation value can accurately characterize the safety and reliability of each loop closing operation strategy. The higher the comprehensive evaluation value, the higher the safety and reliability of the loop closing operation strategy. Therefore, in this embodiment, the alternative loop closing strategy with the highest comprehensive evaluation value is taken as the loop closing operation strategy with the optimal safety evaluation index value.

[0137] In one embodiment, after performing loop closing control on the active distribution network according to the target loop closing operation strategy, the above method may further include:

[0138] First step, obtain the branch current of each power supply branch in the active distribution network after loop closing.

[0139] Second step, judge whether the branch current of each power supply branch is higher than the preset first current upper limit value, and obtain the first judgment result.

[0140] In the third step, if the first judgment result is yes, determine the power supply branch with the branch current higher than the first current upper limit value as the first target branch, and adjust the output power of the distributed power source on the first target branch to the first power setting value.

[0141] In the fourth step, if the first judgment result is no, determine whether the branch current of each power supply branch is higher than the preset second current upper limit value to obtain a second judgment result.

[0142] In the fifth step, if the second judgment result is yes, determine the power supply branch with the branch current higher than the second current upper limit value as the second target branch, and adjust the output power of the distributed power source on the second target branch to the second power setting value.

[0143] Wherein, the first current upper limit value is higher than the second current upper limit value.

[0144] It should be noted that after the loop closing operation in this embodiment, the branch current of each power supply branch in the active distribution network after loop closing is monitored, and the branch current is controlled by a hierarchical control method. Specifically, when the branch current exceeds the first current upper limit value, it indicates that the branch current is in the first-level current range at this time, and the safety hazard of the active distribution network is relatively high. In this regard, in this embodiment, the output power of the distributed power source on the first target branch is adjusted to the first power setting value, and the branch current is reduced by adjusting the output power of the distributed power source to ensure the safe operation of the active distribution network.

[0145] Similarly, when the branch current exceeds the second current upper limit value, it indicates that the branch current is in the second-level current range at this time, and there are also certain safety hazards in the active distribution network at this time. At this time, the output power of the distributed power source on the second target branch is adjusted to the second power setting value, and the branch current can be further reduced by adjusting the output power of the distributed power source.

[0146] In practical applications, the first power setting value is higher than the second power setting value to avoid excessively large adjustment of the output power of the distributed power source and affecting the stable operation of the active distribution network.

[0147] In a specific implementation, adjusting the output power of the distributed power source on the first target branch to the first power setting value specifically includes:

[0148] In the first step, subtract the branch current of the first target branch from the first current upper limit value to obtain a current overlimit value.

[0149] In the second step, if the current overlimit value satisfies the first preset overlimit range, adjust the output power of the distributed power source on the first target branch to the first power setting value according to the preset first power adjustment curve.

[0150] In the third step, if the current over-limit value satisfies the second preset over-limit interval, the output power of the distributed power source on the first target branch is adjusted to the first power setting value according to the preset second power adjustment curve.

[0151] Among them, the interval upper limit value of the first preset over-limit interval is smaller than the interval upper limit value of the second preset over-limit interval; the average slope of the first power adjustment curve is smaller than the average slope of the second power adjustment curve.

[0152] In practical applications, the average slope can be determined by the following process:

[0153] First, extract multiple key data points from the first power adjustment curve or the second power adjustment curve, and determine the slope value corresponding to each key data point;

[0154] Then, the slope values ​​of all key data points are averaged to calculate the average slope.

[0155] It can be understood that this embodiment can adopt a reasonable adjustment scheme for the output power of the distributed power source in a targeted manner according to the over-limit situation of the branch current. During the adjustment process, if the current over-limit value satisfies the first preset over-limit interval, the output power of the distributed power source is adjusted according to the first power adjustment curve with a relatively gentle change; if the current over-limit value satisfies the second preset over-limit interval, the output power of the distributed power source is adjusted according to the second power adjustment curve with a relatively steep change, thereby avoiding the output power of the distributed power source from fluctuating violently in a short period of time and affecting the operating stability of the active distribution network.

[0156] Similarly, in the process of adjusting the output power of the distributed power source on the second target branch to the second power setting value, a solution consistent with the principle of the output power adjustment solution of the distributed power source on the first target branch can be adopted.

[0157] The beneficial effects that can be produced by the active distribution network closed-loop control method provided in this embodiment are described in detail below through a specific example.

[0158] by Figure 2 Taking the active power distribution network with 34 nodes as an example, a photovoltaic power source is configured at the 34th node, and the shape parameter is adopted. is 0.679, The Beta distribution of 1.778 is used to model the photovoltaic power source, and the maximum light intensity is 1.134kW / m 2 Select the ring branch with 28-34 nodes and take the benchmark capacity S B For 1MVA, the reference voltage U B It is 24.9kV.

[0159] For the above configuration, the loop closing operation is performed using the MC (Monte Carlo) method, the traditional semi-invariant method, and the improved loop closing control method for active distribution networks provided in this embodiment (abbreviated as the LHS-GC method). The sampling scale of the MC method is 10,000, and it is considered that the results of the MC method at this sampling scale are accurate. The sampling scale of the LHS is 500. Regarding the loop closing steady-state current in line 26-28 I a The curve graph of can be seen Figure 3 as shown in the figure, where the abscissa represents the loop closing steady-state current in line 26-28 I a and the ordinate represents the cumulative distribution probability of the loop closing steady-state current corresponding to line 26-28 F 1, Figure 3 It can be seen from that in terms of the calculation results of the loop closing steady-state current, the LHS-GC method has higher accuracy compared with the traditional semi-invariant method, and is more fitting to the cumulative probability distribution curve obtained by the MC method.

[0160] Figure 4 The figure shows the loop closing transient current in line 26-28 under the above three loop closing methods I am The curve graph of, where the abscissa represents the loop closing transient current in line 26-28 I am and the ordinate represents the cumulative distribution probability of the loop closing transient current corresponding to line 26-28 F 3, Figure 4 It can be seen from that in terms of the calculation results of the loop closing transient current, the LHS-GC method has higher accuracy compared with the traditional semi-invariant method, and is more fitting to the cumulative probability distribution curve obtained by the MC method.

[0161] Figure 5 The figure shows the error comparison between the LHS-GC method and the traditional semi-invariant method. Among them, the abscissa represents the loop closing steady-state current of the feeders on both sides of the loop closing point I a and I b and the loop closing transient current of the feeders on both sides of the loop closing point I am and I bm , and the ordinate represents the error percentage. Figure 5 It can be seen from that the current error corresponding to the LHS-GC method at the 90% cumulative distribution probability is smaller, and is all lower than 2%. The results prove that the LHS-GC method has a better effect in fitting the cumulative distribution function of the feeder loop closing current and higher accuracy.

[0162] Based on the same general inventive concept, the present invention also protects an active distribution network closed-loop control device. The following describes the active distribution network closed-loop control device provided by the present invention. The active distribution network closed-loop control device described below can be mutually corresponding and referenced with the active distribution network closed-loop control method described above.

[0163] Figure 6 It is a schematic structural diagram of the active distribution network closed-loop control device provided by an embodiment of the present invention.

[0164] As Figure 6 shown, the active distribution network closed-loop control device provided by an embodiment of the present invention specifically includes:

[0165] An acquisition module 210, configured to acquire the operation data and load data of distributed power sources in the closed-loop network topology of the active distribution network;

[0166] A sampling module 220, configured to perform Latin hypercube sampling on the operation data and load data of the distributed power sources to obtain photovoltaic semi-invariants and load semi-invariants;

[0167] A transformation module 230, configured to perform matrix transformation and series expansion on the photovoltaic semi-invariants and load semi-invariants to obtain the cumulative distribution function and probability density function of the closed-loop current;

[0168] An evaluation module 240, configured to acquire the key current data of the feeders on both sides of the closed-loop point under different closed-loop operation strategies, and input the key current data into the cumulative distribution function and probability density function to obtain the safety evaluation index values corresponding to each closed-loop operation strategy;

[0169] A control module 250, configured to use the closed-loop operation strategy with the optimal safety evaluation index value as the target closed-loop operation strategy, and perform closed-loop control on the active distribution network according to the target closed-loop operation strategy.

[0170] Regarding the device in the above embodiment, the specific manners in which each module performs operations have been described in detail in the embodiment related to the method, and will not be elaborated in detail here.

[0171] Figure 7 It is a schematic structural diagram of the electronic device provided by an embodiment of the present invention.

[0172] As Figure 7As shown in the figure, the electronic device may include: a processor 310, a communications interface 320, a memory 330, and a communication bus 340. Among them, the processor 310, the communications interface 320, and the memory 330 communicate with each other through the communication bus 340. The processor 310 may call the logical instructions in the memory 330 to execute the active distribution network closed-loop control method provided by each of the above embodiments.

[0173] In addition, when the logical instructions in the above-mentioned memory 330 are implemented in the form of software functional units and sold or used as independent products, they may be stored in a computer-readable storage medium. Based on such an understanding, the technical solution of the present invention, in essence, or the part that contributes to the prior art, or a part of this technical solution, may be embodied in the form of a software product. This computer software product is stored in a storage medium and includes several instructions for causing a computer device (which may be a personal computer, a server, or a network device, etc.) to execute all or part of the steps of the methods described in various embodiments of the present invention. The foregoing storage medium includes: various media such as USB flash drives, mobile hard disks, read-only memories (ROMs), random access memories (RAMs), magnetic disks, or optical discs that can store program codes.

[0174] On the other hand, the present invention also provides a computer program product. The computer program product includes a computer program that can be stored on a non-transitory computer-readable storage medium. When the computer program is executed by a processor, the computer can execute the active distribution network closed-loop control method provided by each of the above embodiments.

[0175] On yet another aspect, the present invention also provides a non-transitory computer-readable storage medium, on which a computer program is stored. When the computer program is executed by a processor, it is implemented to execute the active distribution network closed-loop control method provided by each of the above embodiments.

[0176] The device embodiments described above are merely illustrative. The units described as separate components may or may not be physically separated, and the components shown as units may or may not be physical units, that is, they may be located in one place, or may be distributed to multiple network units. Some or all of the modules may be selected according to actual needs to achieve the purpose of the solution of this embodiment. Those of ordinary skill in the art can understand and implement it without creative efforts.

[0177] Through the description of the above embodiments, those skilled in the art can clearly understand that each embodiment can be implemented by means of software plus a necessary general hardware platform, and of course, it can also be implemented by hardware. Based on such an understanding, the essence of the above technical solution, or the part that contributes to the prior art, can be embodied in the form of a software product. This computer software product can be stored in a computer-readable storage medium, such as ROM / RAM, magnetic disk, optical disk, etc., and includes several instructions to enable a computer device (which can be a personal computer, server, or network device, etc.) to execute the methods described in each embodiment or some parts of the embodiments.

[0178] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and are not intended to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that they can still modify the technical solutions described in the foregoing embodiments, or perform equivalent replacements for some of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A closed-loop control method for an active distribution network, characterized in that: include: Obtaining the operating data and load data of distributed power sources in the closed-ring network topology of the active distribution network; Performing Latin hypercube sampling on the operation data and load data of the distributed power source to obtain photovoltaic semi-invariants and load semi-invariants; Performing matrix transformation and series expansion on the photovoltaic semi-invariant and the load semi-invariant to obtain a cumulative distribution function and a probability density function of the closed-loop current; Acquire key current data of feeders on both sides of the closing point under different closing operation strategies, input the first key sub-data in the key current data into the cumulative distribution function, and calculate the preliminary closing success rate according to the function output value; When the initial closing loop success rate is higher than the preset success rate threshold, the second key sub-data in the key current data under each closing loop operation strategy is input into the probability density function to calculate the maximum over-limit rate and the average over-line rate of the closing loop current; the initial closing loop success rate, the maximum over-limit rate and the average over-line rate are used as the safety assessment index value corresponding to each closing loop operation strategy; Taking the closing operation strategy with the best safety evaluation index value as the target closing operation strategy, and performing closing control on the active distribution network according to the target closing operation strategy; The closed-loop operation strategy with the best safety assessment index value is determined by the following process: According to the preset screening conditions, the candidate closing strategies are screened from all the closing operation strategies; wherein the preset screening conditions include: the initial closing success rate is higher than the preset success rate threshold, and the maximum crossing rate and the average crossing rate are both lower than their corresponding crossing rate thresholds; The initial closing success rate, the maximum crossing rate and the average crossing rate are weighted to calculate the comprehensive evaluation value of each alternative closing strategy. The calculation formula is: in, Represents the comprehensive evaluation value, Indicates the initial closing success rate The weight value of Indicates the maximum crossing rate The weight value of Indicates the average crossing rate The weight value of The alternative closing strategy with the highest comprehensive evaluation value is used as the closing operation strategy with the best safety evaluation index value; After performing loop closing control on the active distribution network according to the target loop closing operation strategy, the method further includes: Obtain the branch current of each power supply branch in the active distribution network after the ring is closed; Determine whether the branch current of each power supply branch is higher than a preset first current upper limit value, and obtain a first determination result; If the first judgment result is yes, the power supply branch whose branch current is higher than the first current upper limit value is determined as the first target branch, and the branch current of the first target branch is subtracted from the first current upper limit value to obtain a current over-limit value; if the current over-limit value satisfies a first preset over-limit interval, the output power of the distributed power source on the first target branch is adjusted to a first power setting value according to a preset first power adjustment curve; if the current over-limit value satisfies a second preset over-limit interval, the output power of the distributed power source on the first target branch is adjusted to the first power setting value according to a preset second power adjustment curve; Among them, the interval upper limit value of the first preset over-limit interval is smaller than the interval upper limit value of the second preset over-limit interval; the average slope of the first power adjustment curve is smaller than the average slope of the second power adjustment curve; the average slope of the curve is determined by the following process: extracting multiple key data points from the first power adjustment curve or the second power adjustment curve, and determining the slope value corresponding to each key data point; averaging the slope values ​​of all key data points to calculate the average slope of the curve.

2. The active distribution network closed-loop control method according to claim 1, characterized in that: The photovoltaic semi-invariant and the load semi-invariant are subjected to matrix transformation and series expansion to obtain a cumulative distribution function and a probability density function of the closed-loop current, including: Based on the operation data and load data of the distributed power source, a network power flow calculation is performed at a reference operation point to obtain a power flow calculation result; Adding the photovoltaic semi-invariant and the load semi-invariant to calculate the node injection power accumulation; Based on the power flow calculation result, matrix transformation is performed on the accumulated amount of power injected into the node to calculate the semi-invariant of the closed-loop current; The semi-invariant of the closed-loop current is expanded in series, and the cumulative distribution function and probability density function of the closed-loop current are obtained by fitting.

3. The active distribution network closed-loop control method according to claim 1, characterized in that: The first key sub-data include: the first maximum current carrying capacity, the second maximum current carrying capacity, the first current quick-break protection setting value and the second current quick-break protection setting value of the feeders on both sides of the loop closing point; The second key sub-data includes: closed-loop current and preset rated current; The cumulative distribution function includes: a first cumulative distribution sub-function corresponding to the first closed-loop steady-state current of the feeders on both sides of the closed-loop point, a second cumulative distribution sub-function corresponding to the second closed-loop steady-state current, a third cumulative distribution sub-function corresponding to the first closed-loop transient current, and a fourth cumulative distribution sub-function corresponding to the second closed-loop transient current.

4. The active distribution network closed-loop control method according to claim 3, characterized in that: Inputting the first key sub-data in the key current data into the cumulative distribution function, and calculating the preliminary loop closing success rate according to the function output value, including: Inputting the first maximum current carrying capacity into the first cumulative distribution sub-function to obtain a first function output value; Inputting the second maximum current carrying capacity into the second cumulative distribution sub-function to obtain a second function output value; Inputting the first current quick-break protection setting value into the third cumulative distribution sub-function to obtain a third function output value; Inputting the second current quick-break protection setting value into the fourth cumulative distribution sub-function to obtain a fourth function output value; The first function output value, the second function output value, the third function output value and the fourth function output value are integrated to calculate a preliminary loop closing success rate.

5. The active distribution network closed-loop control method according to claim 1, characterized in that: After performing loop closing control on the active distribution network according to the target loop closing operation strategy, the method further includes: If the first judgment result is no, then judging whether the branch current of each power supply branch is higher than a preset second current upper limit value, and obtaining a second judgment result; If the second judgment result is yes, the power supply branch whose branch current is higher than the second current upper limit value is determined as the second target branch, and the output power of the distributed power supply on the second target branch is adjusted to the second power setting value; Wherein, the first current upper limit value is higher than the second current upper limit value.

6. An active distribution network closed-loop control device, characterized in that: include: An acquisition module, used to acquire the operation data and load data of the distributed power source in the closed-loop network topology of the active distribution network; A sampling module, used for performing Latin hypercube sampling on the operation data and load data of the distributed power source to obtain photovoltaic semi-invariants and load semi-invariants; A transformation module, used for performing matrix transformation and series expansion on the photovoltaic semi-invariant and the load semi-invariant to obtain a cumulative distribution function and a probability density function of the closed-loop current; An evaluation module is used to obtain key current data of feeders on both sides of the closing point under different closing operation strategies, and input the first key sub-data in the key current data into the cumulative distribution function, and calculate the preliminary closing success rate according to the function output value; When the initial closing loop success rate is higher than the preset success rate threshold, the second key sub-data in the key current data under each closing loop operation strategy is input into the probability density function to calculate the maximum over-limit rate and the average over-line rate of the closing loop current; the initial closing loop success rate, the maximum over-limit rate and the average over-line rate are used as the safety assessment index value corresponding to each closing loop operation strategy; A control module, used to take the closing operation strategy with the best safety assessment index value as the target closing operation strategy, and perform closing control on the active distribution network according to the target closing operation strategy; The closed-loop operation strategy with the best safety assessment index value is determined by the following process: According to the preset screening conditions, the candidate closing strategies are screened from all the closing operation strategies; wherein the preset screening conditions include: the initial closing success rate is higher than the preset success rate threshold, and the maximum crossing rate and the average crossing rate are both lower than their corresponding crossing rate thresholds; The initial closing success rate, the maximum crossing rate and the average crossing rate are weighted to calculate the comprehensive evaluation value of each alternative closing strategy. The calculation formula is: in, Represents the comprehensive evaluation value, Indicates the initial closing success rate The weight value of Indicates the maximum crossing rate The weight value of Indicates the average crossing rate The weight value of The alternative closing strategy with the highest comprehensive evaluation value is used as the closing operation strategy with the best safety evaluation index value; After performing loop closing control on the active distribution network according to the target loop closing operation strategy, the control module is further used to: Obtain the branch current of each power supply branch in the active distribution network after the ring is closed; Determine whether the branch current of each power supply branch is higher than a preset first current upper limit value, and obtain a first determination result; If the first judgment result is yes, the power supply branch whose branch current is higher than the first current upper limit value is determined as the first target branch, and the branch current of the first target branch is subtracted from the first current upper limit value to obtain a current over-limit value; if the current over-limit value satisfies a first preset over-limit interval, the output power of the distributed power source on the first target branch is adjusted to a first power setting value according to a preset first power adjustment curve; if the current over-limit value satisfies a second preset over-limit interval, the output power of the distributed power source on the first target branch is adjusted to the first power setting value according to a preset second power adjustment curve; Among them, the interval upper limit value of the first preset over-limit interval is smaller than the interval upper limit value of the second preset over-limit interval; the average slope of the first power adjustment curve is smaller than the average slope of the second power adjustment curve; the average slope of the curve is determined by the following process: extracting multiple key data points from the first power adjustment curve or the second power adjustment curve, and determining the slope value corresponding to each key data point; averaging the slope values ​​of all key data points to calculate the average slope of the curve.

7. An electronic device comprising a memory, a processor, and a computer program stored in the memory and running on the processor, characterized in that: When the processor executes the program, the active power distribution network closed-loop control method as described in any one of claims 1 to 5 is implemented.

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