Disclosure of Invention
Aiming at the defects of the existing power supply capacity assessment method, the invention provides a low-voltage area flexible interconnection planning method considering the power supply capacity of a power distribution network, which is used for solving the technical problem that the theoretical upper limit and the load characteristic are difficult to consider in the current power supply capacity assessment process of the power distribution network, and can more reasonably assess the power supply capacity of a system under the condition of installing the low-voltage area flexible interconnection device and provide references for planning and construction of the low-voltage area flexible interconnection device.
The invention adopts the following technical scheme:
A flexible interconnection planning method for a low-voltage transformer area considering power supply capacity of a power distribution network comprises the following steps:
generating a variable matrix representing the installation position and port capacity of the flexible interconnection device and constraint conditions of flexible interconnection device planning, and acquiring a possible planning scheme set of the flexible interconnection device; the constraint conditions of flexible interconnection device planning comprise maximum installation quantity, maximum installation capacity and maximum port quantity;
The planning scheme of each flexible interconnection device obtains the maximum power supply capacity of the power distribution network under the condition of freely distributed load, which is called theoretical TSC, based on the capacity constraint of the power distribution network equipment and the N-1 safety constraint criterion;
The planning scheme of each flexible interconnection device obtains the maximum power supply capacity of the power distribution network under the actual load characteristic, which is called characteristic TSC, based on the actual load distribution characteristic and the growth rule according to the obtained maximum power supply capacity of the power distribution network; determining the current load of each area as a reference value, enabling the load to increase according to iteration step length to represent actual distribution characteristics and an increase rule of the load, judging whether each iteration can meet equipment capacity constraint and N-1 safety constraint under the current flexible interconnection planning scheme, and halving the iteration step length until convergence to obtain the maximum power supply capacity of the power distribution network under the actual load characteristics when the constraint cannot be met;
based on the obtained theoretical TSC and the characteristic TSC, calculating a generalized capacity-to-load ratio of a planning scheme of each flexible interconnection device;
And solving to obtain an optimal planning scheme of the flexible interconnection device, comprising an optimal installation position and capacity, by taking the maximum characteristic TSC and the minimum generalized capacity ratio as objective functions based on a planning scheme set of the possible flexible interconnection device, so as to finish flexible interconnection planning of a low-voltage area taking the power supply capacity of the power distribution network into consideration.
Further, the calculating method of the feature TSC specifically comprises the following steps:
Determining the current load of each area as a reference value, and the iteration step length and convergence accuracy of each area;
the load is increased according to the iteration step length, and whether the equipment capacity constraint and the N-1 safety constraint can be met or not is judged under the current flexible interconnection planning scheme; when the constraint cannot be met, halving the iteration step length;
And judging whether convergence accuracy is achieved, if not, repeating the steps, otherwise, outputting the sum of all the area loads as the maximum power supply capacity of the power distribution network under the actual load characteristics.
Further, the generalized load-to-volume ratioThe calculation method comprises the following steps:
Wherein,For the purpose of the theoretical TSC,Is a characteristic TSC.
Further, the variable matrix representing the installation position and the port capacity of the flexible interconnection device is specifically as follows:
Wherein: v is a 0-1 variable, which represents whether the flexible interconnection device is connected with the corresponding station area, 1 represents that the station area is connected with the flexible interconnection device, and otherwise, the flexible interconnection device is not connected with the station area; Representing the maximum number of installations of the flexible interconnect, nd represents the number of bays within the planned area.
Further, the constraint of the maximum installation capacity is expressed as follows:
Wherein: representing the maximum design capacity of the flexible interconnect numbered r, a capacity of 0 represents that the flexible interconnect is not installed.
Further, the constraint of the maximum number of ports is expressed as follows:
Wherein: Is a 0-1 variable, representing whether a flexible interconnection device with the number r is connected with a station area i or not; representing the number of ports designated by the flexible interconnect device numbered r, nd represents the number of zones within the planned area.
Further, the method further comprises the following steps:
And performing secondary optimization on the optimal planning scheme of the flexible interconnection device obtained by solving by taking the minimum installation cost of the flexible interconnection device as an objective function to obtain the final installation position and capacity configuration scheme of the flexible interconnection device.
An electronic device comprises a memory, a processor and a computer program stored on the memory and capable of running on the processor, wherein the processor realizes the flexible interconnection planning method of a low-voltage station area considering the power supply capacity of a power distribution network when executing the computer program.
A storage medium containing computer executable instructions which when executed by a computer processor implement a low voltage grid flexible interconnect planning method as described that takes into account power supply capabilities of a power distribution grid.
A computer program product comprising computer programs/instructions which when executed by a processor implement the steps of the method for planning flexible interconnection of low voltage areas taking into account power supply capacity of a power distribution network.
Compared with the prior art, the invention has at least the following beneficial effects:
The power supply capacity evaluation method considering the load distribution characteristics of the power distribution network firstly establishes a power supply capacity calculation model of the power distribution network with iteratively increased load, and firstly provides a power supply capacity evaluation index of the power distribution network based on the actual load characteristics, so that the rationality of the power distribution network structure can be effectively measured; and a flexible interconnection equipment planning model which takes the power supply capacity improvement and the economy into account is established, so that the defects of the existing low-voltage flexible interconnection planning index and the limitation of the planning method are effectively overcome. The method can evaluate the influence of the installation scheme of the low-voltage flexible interconnection device on the power supply capacity of the system more comprehensively, and has important practical significance for flexible interconnection reconstruction construction of the power distribution network.
Furthermore, the characteristic TSC index considers the distribution characteristics and the growth mode of the actual load, and the port transmission characteristics of the flexible interconnection device of the station area are utilized to transfer the power between different stations, so that the lifting effect of the flexible interconnection device on the power supply capacity of the power distribution network is evaluated conveniently.
Furthermore, the generalized capacity-to-load ratio index gives an upper limit of power supply capacity increase under a specific network structure by utilizing a theoretical TSC, and the construction efficiency of the power distribution network in flexible interconnection transformation under actual load conditions is reflected in a ratio form, so that the increase space of the power supply capacity of the system under the specific load conditions can be conveniently estimated.
Furthermore, based on the characteristic TSC and the generalized capacity ratio index, the installation position and capacity of the flexible interconnection device of the low-voltage transformer area are planned, the access position of the flexible interconnection device with any number and port number can be optimized, and the optimal economic result is given through secondary optimization, so that technicians are helped to form a reasonable flexible interconnection device installation scheme.
In summary, the invention considers the characteristics of the network structure and the actual load to enable the power supply capacity evaluation to be closer to the actual, and simultaneously the provided low-voltage area flexible interconnection device site selection and volume determination planning algorithm effectively improves the accuracy of the low-voltage area flexible interconnection planning, thereby having good application prospects.
The technical scheme of the invention is further described in detail through the drawings and the embodiments.
Detailed Description
The following description of the embodiments of the present invention will be made clearly and fully with reference to the accompanying drawings, in which it is evident that the embodiments described are some, but not all embodiments of the invention. All other embodiments, which can be made by those skilled in the art based on the embodiments of the invention without making any inventive effort, are intended to be within the scope of the invention.
In the description of the present invention, it will be understood that the terms "comprises" and "comprising," when used in this specification, specify the presence of stated features, integers, steps, operations, elements, and/or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and/or groups thereof.
It should be understood that although the terms first, second, third, etc. may be used to describe the preset ranges, etc. in the embodiments of the present invention, these preset ranges should not be limited to these terms. These terms are only used to distinguish one preset range from another. For example, a first preset range may also be referred to as a second preset range, and similarly, a second preset range may also be referred to as a first preset range without departing from the scope of embodiments of the present invention.
It is also to be understood that the terminology used in the description of the invention is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. As used in this specification and the appended claims, the singular forms "a," "an," and "the" are intended to include the plural forms as well, unless the context clearly indicates otherwise.
According to the flexible interconnection planning method for the low-voltage transformer area, the influence of load distribution and growth characteristics on the power supply capacity evaluation of the power distribution network is analyzed, the flexible interconnection planning method for the low-voltage transformer area is provided, the construction efficiency of flexible interconnection reconstruction of the power distribution network under the actual load condition can be evaluated, and an optimal installation scheme of the flexible interconnection device is formulated.
The invention relates to a flexible interconnection planning method for a low-voltage transformer area considering power supply capacity of a power distribution network, which is shown in fig. 1 and comprises the following steps:
S1, generating a variable matrix representing the installation position and port capacity of a flexible interconnection device and constraint conditions of flexible interconnection device planning, and acquiring a possible planning scheme set of the flexible interconnection device; the constraint conditions of flexible interconnection device planning comprise maximum installation quantity, maximum installation capacity and maximum port quantity; the method specifically comprises the following substeps:
S11, generating a variable matrix representing the installation position and port capacity of the flexible interconnection device;
The variable matrix is shown in formula (1):
Wherein: The number of the areas in the planning area is v is a 0-1 variable, which represents whether the flexible interconnection device is connected with the corresponding area, 1 represents that the area is connected with the flexible interconnection device, and otherwise, the area is not connected with the flexible interconnection device; Representing the maximum number of installations of the flexible interconnect. Each row of the matrix represents a separate flex interconnect mounting scheme. It should be noted that hereThe upper limit of the number of the flexible interconnection devices acceptable in planning is represented, the upper limit is influenced by factors such as cost and construction space, and the number of the flexible interconnection devices finally installed is not represented.
S12, generating constraint conditions of flexible interconnection device planning, wherein the constraint conditions comprise maximum installation quantity, maximum installation capacity and maximum port quantity;
Wherein the maximum number of installations has been determined by the formula (1)The number of flexible interconnection devices to be mounted can be freely increased or decreased within the limit range of the number of rows of the matrix.
The capacity constraint that the flexible interconnect should meet is as shown in equation (2) by the skill level and construction space constraints:
Wherein: Representing the maximum design capacity of the flexible interconnect means numbered r. A capacity of 0 represents that the flexible interconnect is not installed.
The flexible interconnect port number constraint is as shown in equation (3):
Wherein: is a 0-1 variable representing whether the flexible interconnection device numbered r in the formula (1) is connected with the station area i; representing the number of ports designated by the flexible interconnect means numbered r.
S2, a planning scheme of each flexible interconnection device obtains the maximum power supply capacity of the power distribution network under the condition of freely distributed load, which is called theoretical TSC, based on capacity constraint of the power distribution network equipment and N-1 safety constraint criteria;
The calculation formula of the theoretical TSC is shown in formula (4):
Wherein,Is the total apparent power generated by the users of zone i.
The constraint conditions to be met by the power and flexible interconnection device of the platform area under the normal operation condition are shown in a formula (5):
Wherein:， AndThe load power on the distribution transformer of the station area i, the feeder j and the main transformer k are respectively;、 AndThe port number sets are respectively a station number set which belongs to a feeder j, a feeder number set which belongs to a main transformer k and all port number sets in a single flexible interconnection device;、、 AndThe port capacity of the flexible interconnection device is connected with the distribution transformer capacity of the station area i, the outlet capacity of the feeder line j, the main transformer k capacity and the station area i; The power transmitted by the port of the flexible interconnection device connected with the station area i is positive value representing the power absorbed by the port and negative value representing the power emitted by the port; is the net absorbed power of the flexible interconnect.
The constraint conditions that the power and flexible interconnection device of the platform region needs to meet under the condition of a certain element fault, namely N-1 fault, are shown in a formula (6):
Wherein: AndRespectively representing a new station area number set under the feeder j and a new feeder number set under the main transformer k after network reconstruction under the fault condition u; Representing the power transferred to the port of the flexible interconnect device to which the zone i is connected in the event of a fault condition u. In the actual power distribution network planning, when part of important elements are in failure, the power distribution network does not have any corresponding scheduling scheme, so that the condition of operation constraint, such as power loss island formed by distribution transformer failure of a transformer area, can be met. Such cases do not take into account the N-1 failure set.
S3, obtaining the maximum power supply capacity of the power distribution network under the actual load characteristic, which is called characteristic TSC, based on the actual load distribution characteristic and the growth rule according to the maximum power supply capacity model of the power distribution network obtained in the step S2; determining the current load of each area as a reference value, enabling the load to increase according to iteration step length to represent actual distribution characteristics and an increase rule of the load, judging whether equipment capacity constraint and N-1 safety constraint can be met under the current flexible interconnection planning scheme (obtained based on a variable matrix representing the installation position and port capacity of a flexible interconnection device) for each iteration, and halving the iteration step length until convergence is achieved to obtain the maximum power supply capacity of the power distribution network under the actual load characteristics when the constraint cannot be met; referring to fig. 2, the specific steps are as follows:
S31, determining the current load of each areaAs a reference value, the iteration step of each zoneAnd convergence accuracy;
s32, increasing the load according to the iteration step length, and judging whether the equipment capacity constraint and the N-1 safety constraint can be met under the current flexible interconnection planning scheme; when the constraint cannot be met, halving the iteration step length;
The method for judging whether the equipment capacity constraint and the N-1 safety constraint can be met under the current flexible interconnection planning scheme comprises the following steps: and directly substituting the parameters under the current flexible interconnection planning scheme into the parameters (5) - (6) to judge whether the parameters are met.
S33, judging whether convergence accuracy is achieved, if not, repeating the steps, otherwise, outputting the sum of all the area loads as a result.
S4, calculating a generalized capacity-to-load ratio based on the theoretical TSC and the characteristic TSC obtained in the step S2 and the step S3;
the calculation formula of the generalized capacity-to-load ratio is shown as (7):
Wherein,In order to be a generalized capacity-to-load ratio,For the purpose of the theoretical TSC,Is a characteristic TSC.
S5, planning the installation position and capacity of the flexible interconnection device of the low-voltage station area based on the characteristic TSC obtained in the step S3 and the generalized capacity-to-load ratio index obtained in the step S4.
In a specific embodiment, the specific steps are as follows:
Taking the maximum characteristic TSC and the minimum generalized capacity ratio as objective functions, and solving the optimal installation position and capacity of the flexible interconnection device;
The solution model is shown in formula (8):
Wherein: AndRespectively represent in-site selection schemesConstant volume schemeThe following characteristic TSC and generalized capacity-to-load ratio;。
In a more preferred embodiment, the method further comprises the step of performing secondary optimization on the result obtained in the previous step by taking the minimum installation cost of the flexible interconnection device as an objective function to obtain a final installation position and capacity configuration scheme, wherein the specific steps are as follows:
Taking the maximum characteristic TSC and the minimum generalized capacity ratio as objective functions, and solving the optimal installation position and capacity of the flexible interconnection device;
the quadratic optimization model is shown in formula (9):
Wherein: Representative in-site selection schemeConstant volume schemeThe cost can be reduced to the sum of the capacities of all flexible interconnection devices when the installation type of the flexible interconnection devices is single.AndRespectively represent the optimal solution sets of the addressing and the constant volume schemes obtained by solving the model of the formula (8).
In the optimization process, an optimization method such as an NSGA-II multi-objective optimization algorithm can be adopted for solving, and fig. 3 is a flow chart of a secondary optimization based on cost, wherein the secondary optimization is achieved by taking the maximum characteristic TSC and the minimum generalized capacity ratio as objective functions and using the NSGA-II multi-objective optimization algorithm to solve the optimal installation position and capacity of the flexible interconnection device. In the figure, a population is initialized to serve as a possible planning scheme set of the flexible interconnection device, the planning scheme set is fed back to a calculation module, linear programming method calculation theory TSC, iterative method calculation feature TSC and generalized capacity-to-load ratio calculation are sequentially carried out on each scheme, the calculation result is fed back to an optimizing module to carry out NSGA-II multi-objective optimization after fitness function calculation is carried out on the calculation result, and the final result is subjected to cost-based secondary optimization to obtain a final optimal scheme.
The effects of the present invention are further described with reference to the following specific examples:
as shown in fig. 4, the distribution network is constructed based on the IEEE-14 node calculation example, and the basic data of the distribution network in fig. 4 are shown in table 1:
Table 1 network parameters
The base station load reference value of the network is shown in table 2:
Table 2 load reference value
The increment step length of each platform region characteristic TSC solution is 0.05 times of a load reference value, and a maximum of 4 groups of two-port flexible interconnection devices are planned to be installed, wherein the maximum capacity of the flexible interconnection devices is 0.63 MV. The initial population size in NSGA-II algorithm is 200, and the evolution algebra is 200 generations. The best installation scheme calculated according to the planning method shown in fig. 3 is shown in table 3:
Table 3 best mounting solution
By using the power supply capability evaluation method of the invention, the power distribution network before and after flexible interconnection is installed is compared, and the results are shown in table 4:
table 4 comparison of power supply capability indicators
In addition, in order to further highlight the effect of the scheme of the present invention, two cases are set in this embodiment, case 1 represents a single-target flexible interconnection planning scheme using only the theoretical TSC as an objective function, and case 2 represents a multi-target planning scheme using the characteristic TSC and the generalized capacity ratio. The power supply capacity indexes of the two are compared, and the results are shown in table 5:
Table 5 comparison of planning effects
In summary, the influence of load distribution and growth characteristics on the power supply capacity evaluation of the power distribution network is analyzed, and the flexible interconnection planning method for the low-voltage transformer area considering the power supply capacity of the power distribution network is provided, so that the construction efficiency of flexible interconnection reconstruction of the power distribution network under the actual load condition can be evaluated, and an optimal installation scheme of the flexible interconnection device is formulated.
Corresponding to the embodiment of the low-voltage area flexible interconnection planning method considering the power supply capacity of the power distribution network, the invention further provides electronic equipment, which comprises one or more processors, and the electronic equipment is used for realizing the low-voltage area flexible interconnection planning method considering the power supply capacity of the power distribution network in the embodiment.
The apparatus embodiments may be implemented in software, or in hardware or a combination of hardware and software. Taking a software implementation as an example, as a device in a logic sense, a processor of any device with data processing capability reads corresponding computer program instructions in a nonvolatile memory to a memory to run, and the device mainly includes the processor, the memory, a network interface, and the nonvolatile memory, and in addition, the any device with data processing capability in an embodiment generally includes other hardware according to an actual function of the any device with data processing capability, which is not described herein.
The implementation process of the functions and roles of each unit in the above device is specifically shown in the implementation process of the corresponding steps in the above method, and will not be described herein again.
For the device embodiments, reference is made to the description of the method embodiments for the relevant points, since they essentially correspond to the method embodiments. The apparatus embodiments described above are merely illustrative, wherein the elements illustrated as separate elements may or may not be physically separate, and the elements shown as elements may or may not be physical elements, may be located in one place, or may be distributed over a plurality of network elements. Some or all of the modules may be selected according to actual needs to achieve the purposes of the present invention. Those of ordinary skill in the art will understand and implement the present invention without undue burden.
The embodiment of the invention also provides a computer readable storage medium, and a program is stored on the computer readable storage medium, and when the program is executed by a processor, the method for planning the flexible interconnection of the low-voltage area taking the power supply capacity of the power distribution network into consideration in the embodiment is realized.
The computer readable storage medium may be an internal storage unit, such as a hard disk or a memory, of any of the data processing enabled devices described in any of the previous embodiments. The computer readable storage medium may also be any device having data processing capabilities, such as a plug-in hard disk, a smart memory card (SMART MEDIA CARD, SMC), an SD card, a flash memory card (FLASH CARD), or the like, provided on the device. Further, the computer readable storage medium may include both internal storage units and external storage devices of any data processing device. The computer readable storage medium is used for storing the computer program and other programs and data required by the arbitrary data processing apparatus, and may also be used for temporarily storing data that has been output or is to be output.
Although the invention has been described in detail with reference to the foregoing embodiments, it will be understood by those of ordinary skill in the art that: the technical scheme described in the foregoing embodiments can be modified or some technical features thereof can be replaced by equivalents; such modifications and substitutions do not depart from the spirit and scope of the technical solutions of the embodiments of the present invention.