Distribution network reconfiguration and coordinated maintenance model considering voltage deviation

Abstract

The application discloses a power distribution network reconstruction and coordinated maintenance model considering voltage deviation, which is used for obtaining a global optimal solution of maintenance scheduling and network topology. The power distribution network reconstruction and coordinated maintenance model is established through the following steps: S01: a model of line maintenance optimization scheduling of the power distribution network is established according to maintenance costs affected by human resources and load states in different time periods; S02: a power distribution network reconstruction model with a target function of minimum network loss and voltage deviation is established according to the operation mode of the power distribution network, and the topology, power flow and voltage constraint of the power distribution network reconstruction are analyzed; S03: coupling constraints of the line maintenance optimization scheduling and the power distribution network reconstruction are established according to line connection state variables and line maintenance variables; and S04: a power distribution network reconstruction and coordinated maintenance model considering voltage deviation is established with a target function of minimum maintenance cost, network loss and voltage deviation. The application can select the optimal operation mode of the system, and effectively reduces the maintenance scheduling and reconstruction cost of the system.

Description

Technical Field

[0001] The present invention relates to the field of distribution network optimization and scheduling, and in particular to a distribution network reconstruction and coordinated maintenance model considering voltage deviation. Background Art

[0002] The distribution network is an important part of the power system. The distribution network can ensure that electricity is reliably provided to users. For many cities in China that are developing rapidly, the development of my country's distribution network is still insufficient. In order to cope with the rapid growth of power load and the increasing demand for power quality, the development of the distribution network is facing more challenges. Improving the power supply resilience of the distribution network, optimizing the grid operation structure, and improving the system resilience have become the current research directions. Distribution network reconstruction is one of the methods to improve the system operation structure and enhance network resilience. In the formulation of the maintenance plan, when the maintenance line is offline, it will cause load power outages. In order to restore the power outage in the non-maintenance area caused by the line break, the switching status of the lines in the distribution network can be changed to reconstruct the network, change the grid operation structure, restore the power-off load, and optimize the grid operation.

[0003] During maintenance, the lines initially inspected do not participate in distribution network reconstruction. The new topology is always formed based on network changes in non-maintenance areas. When lines are not under maintenance, distribution network reconstruction re-incorporates the lines under maintenance, optimizing the entire network. Therefore, the impact of the distribution network maintenance plan on reconstruction is the impact of line status. The maintenance plan is based on the most economical maintenance period. Based on this maintenance plan, the distribution network determines whether lines require reconstruction. If the line status changes, reconstruction optimization is performed. If the line status remains unchanged, reconstruction optimization is not required to restore loads. With system resilience as the goal, the optimal power supply path is determined to ensure normal distribution network operation. Due to the complexity of distribution network maintenance, manual maintenance plans are generally compiled based on the maintenance personnel's own experience, selecting load restoration in non-maintenance areas. This restoration method is only a feasible solution. The load restoration path determined solely by the maintenance personnel lacks qualitative indicators and is often not the optimal power supply path. When the maintenance task begins, not only the lines under maintenance lose power, but also some non-maintenance areas are affected and lose power. Summary of the Invention

[0004] In response to the problem of high maintenance scheduling and reconstruction costs in distribution network maintenance in the existing technology, the present invention provides a distribution network reconstruction coordinated maintenance model that takes voltage deviation into account. The model is constructed with minimum maintenance cost, network loss and voltage deviation as objective functions, and can select the optimal operation mode of the system, effectively reducing the system maintenance scheduling and reconstruction costs.

[0005] The following are the technical solutions of the present invention.

[0006] A distribution network reconstruction and coordinated maintenance model considering voltage deviation is used to find the global optimal solution for maintenance scheduling and network topology. The distribution network reconstruction and coordinated maintenance model is established through the following steps:

[0007] S01: Establish a model for optimizing the maintenance scheduling of distribution network lines based on the maintenance costs affected by human resources and load conditions in different time periods;

[0008] S02: Based on the operation mode of the distribution network, analyze the topology, power flow, and voltage constraints of the distribution network reconstruction, and establish a distribution network reconstruction model with minimum network loss and voltage deviation as the objective function;

[0009] S03: Based on the line connection state variables and line maintenance variables, establish the coupling constraints of the distribution network line maintenance optimization scheduling and distribution network reconstruction;

[0010] S04: Taking the minimum maintenance cost, network loss and voltage deviation as the objective function, a distribution network reconstruction coordinated maintenance model considering voltage deviation is established.

[0011] Preferably, step S01 includes:

[0012] S11: Analyze the maintenance cost and line maintenance status, and establish the objective function for distribution network line maintenance optimization:

[0013]

[0014] Where: H l,t is the maintenance cost of line l at time t, Y l,t is the open and closed state of line l at time t. When the line is closed normally, Y l,t =1, when the line is disconnected for maintenance, Y l,t =0;

[0015] S12: Analyze maintenance duration limitations and establish constraints on line off-grid time and required total maintenance duration:

[0016] Where: MD L,l is the required maintenance duration of line l, NT is the horizontal axis coordinate of maintenance scheduling;

[0017] S13: Analyze the relationship between the maintenance duration phase and the allowable maintenance time window, and establish the constraints of the allowable maintenance time window given by the system operator:

[0018]

[0019] Where: It is the allowable maintenance time window given by the system operator;

[0020] S14: Analyze the relationship between the maintenance indicator variable and the line status, and establish the following maintenance start and stop constraints based on the binary characteristics of the indicator variable:

[0021]

[0022]

[0023]

[0024]

[0025] Where: p l,t and q l,t They are the maintenance start and end status indicator variables of line l at time t. When the maintenance starts, p l,t =1, otherwise 0, when the maintenance is completed q l,t =1, otherwise 0;

[0026] S15: If the maintenance duration is long, analyze the minimum maintenance time and maintenance interval, and establish the following maintenance sub-constraints:

[0027]

[0028]

[0029] Where: MT l on is the minimum maintenance duration, MT l off is the maintenance time interval.

[0030] Preferably, step S02 includes:

[0031] S21: Analyze the operational characteristics of network distribution network reconstruction and establish the reconstruction goal of minimizing network losses and bus voltage deviation:

[0032] Where: Rated voltage is V N ; Network loss is P inj The voltage deviation is expressed as the absolute value of the voltage amplitude deviation. calculate;

[0033] S22: Analyze network topology connections, introduce topology relationship variables, and establish radial topology connection constraints for the distribution network:

[0034]

[0035]

[0036]

[0037]

[0038] Where: β mn Indicates that if node n is the parent node of node m, then β mn =1, otherwise 0; β nm Indicates that if node m is the parent node of node n, then β nm =1, otherwise 0; the substation node is the root node; except the root node, all other nodes have only one parent node; N is the set of all distribution buses; N s It is a collection of substation buses;

[0039] S23: Analyze the power balance conditions of distribution network nodes and establish node power balance constraints:

[0040]

[0041]

[0042] Where: PD m and QD m are the active load and reactive load of node m respectively; P mn and Q mn is the active power and reactive power of line mn; ENS m Active load shedding; QR m is the reactive load shedding ratio;

[0043] S24: Analyze the power flow of the line and establish the active power and reactive power flow constraints on line mn:

[0044]

[0045]

[0046] Where: B l and G l are the conductance and susceptance of line l, is the parallel conductance of line l to ground; auxiliary variable Represents the voltage of line l; r l and t l are the auxiliary variables of line l;

[0047] S25: Analyze the relationship between auxiliary variables and node voltages, and establish auxiliary voltage variable constraints:

[0048]

[0049]

[0050]

[0051] Where: represents the voltage of line l, α l Indicates the connection status of line l during line reconstruction; when line l is connected, α l =1, When line l is disconnected, α l =0,

[0052] S26: Analyze and establish constraints between auxiliary variables and voltage limits:

[0053]

[0054]

[0055]

[0056]

[0057] Where: V n,max and V m,max Represent the maximum voltage of nodes m and n respectively;

[0058] S27: Analyze and establish current amplitude constraints for auxiliary variables:

[0059]

[0060] Where: A l ,B l ,C l ,D l is the current amplitude constraint coefficient of the auxiliary variable, I l,max is the maximum current of line 1.

[0061] Preferably, step S03 includes:

[0062] The relationship between line state variables and maintenance variables is analyzed, and the relationship between line maintenance start-stop status and distribution network topology reconstruction is considered to establish the coupling constraints for distribution network line maintenance optimization scheduling and distribution network reconstruction:

[0063]

[0064]

[0065]

[0066] Where: Y l,t is the open and closed state of line l at time t; p l,t and q l,tare the maintenance start and end status indicator variables of line l at time t; α l,t represents the connection state of line l at time t during line reconstruction; the coupling constraint restricts the line connection state to be disconnected if the line is under maintenance; at the same time, the coupling constraint also ensures that the network is only reconstructed at the beginning or end of line maintenance.

[0067] Preferably, step S04 includes:

[0068] S41: A distribution network reconstruction and coordinated maintenance model considering voltage deviation is established. The model optimization objectives are as follows:

[0069]

[0070] S42: The model constraints are as follows:

[0071] Maintenance constraints:

[0072]

[0073]

[0074]

[0075]

[0076]

[0077]

[0078]

[0079] Refactoring constraints:

[0080]

[0081]

[0082]

[0083]

[0084]

[0085]

[0086]

[0087]

[0088]

[0089]

[0090]

[0091]

[0092]

[0093]

[0094]

[0095] Coupling constraints:

[0096]

[0097]

[0098] The substantial effects of the present invention include: (1) starting from the perspective of the actual operation of the power system, the operating status of the distribution network system is analyzed when considering line maintenance optimization scheduling and distribution network reconstruction; (2) taking the minimum maintenance cost, network loss and voltage offset as the objective function, a distribution network reconstruction coordinated maintenance model considering voltage deviation is constructed; (3) the method proposed in the present invention can select the optimal operating mode of the system, effectively reduce the system maintenance scheduling and reconstruction costs, and provide a powerful analysis method for distribution network maintenance and reconstruction problems. BRIEF DESCRIPTION OF THE DRAWINGS

[0099] Figure 1 Schematic diagram of a method flow in an embodiment of the present invention;

[0100] Figure 2 A schematic diagram of the IEEE 33-node system used in an embodiment of the present invention;

[0101] Figure 3 The reconstructed distribution network model before maintenance calculated by the embodiment of the present invention;

[0102] Figure 4 A reconstructed distribution network model under maintenance calculated according to an embodiment of the present invention;

[0103] Figure 5 The reconstructed distribution network model after maintenance calculated by the embodiment of the present invention;

[0104] Figure 6 The node voltage offset calculated with or without the proposed model according to the embodiment of the present invention;

[0105] Figure 7 The network loss with and without the proposed model is calculated according to the embodiment of the present invention. DETAILED DESCRIPTION

[0106] To make the objectives, technical solutions, and advantages of the embodiments of the present invention more clear, the technical solutions will be clearly and completely described below in conjunction with the embodiments. Obviously, the embodiments described are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0107] It should be understood that in various embodiments of the present invention, the size of the sequence number of each process does not mean the order of execution. The execution order of each process should be determined by its function and internal logic, and should not constitute any limitation on the implementation process of the embodiments of the present invention.

[0108] It should be understood that in the present invention, "include" and "have" and any variations thereof are intended to cover non-exclusive inclusions. For example, a process, method, system, product or apparatus that includes a series of steps or units is not necessarily limited to those steps or units explicitly listed, but may include other steps or units not explicitly listed or inherent to these processes, methods, products or apparatuses.

[0109] The technical solution of the present invention is described in detail below with reference to specific embodiments. The embodiments may be combined with each other, and the same or similar concepts or processes may not be described in detail in some embodiments.

[0110] Example:

[0111] This embodiment provides a distribution network reconstruction and coordinated maintenance model considering voltage deviation, which is used to find the global optimal solution for maintenance scheduling and network topology. The distribution network reconstruction and coordinated maintenance model of this embodiment is as follows: Figure 1 The following steps are shown to build:

[0112] Step 1: Based on the maintenance costs affected by human resources and load conditions in different time periods, a model for optimizing the maintenance scheduling of distribution network lines is established. The main implementation steps are as follows:

[0113] (1) Analyze the maintenance cost and line maintenance status, and establish the objective function for optimizing distribution network line maintenance:

[0114]

[0115] Where: H l,t is the maintenance cost of line l at time t, Y l,t is the open and closed state of line l at time t. When the line is closed normally, Y l,t =1, when the line is disconnected for maintenance, Y l,t =0.

[0116] (2) Analyze maintenance duration limitations and establish constraints on line off-grid time and required total maintenance duration:

[0117] Where: MD L,l is the required maintenance duration of line l, and NT is the horizontal axis coordinate of the maintenance scheduling.

[0118] (3) Analyze the relationship between the maintenance duration phase and the allowable maintenance time window, and establish the constraints of the allowable maintenance time window given by the system operator:

[0119]

[0120] Where: It is the allowable maintenance time window given by the system operator.

[0121] (4) Analyze the relationship between the maintenance indicator variables and the line status, and establish the following maintenance start and stop constraints based on the binary characteristics of the indicator variables:

[0122]

[0123]

[0124]

[0125]

[0126] Where: p l,t and q l,t are the maintenance start and end status indicator variables of line l at time t. When the maintenance starts, p l,t =1, otherwise 0. When the maintenance is completed, q l,t =1, otherwise 0.

[0127] (5) If the maintenance duration is relatively long, analyze the minimum maintenance time and maintenance interval, and establish the following maintenance sub-constraints:

[0128]

[0129]

[0130] Where: MT l on is the minimum maintenance duration, MT l off is the maintenance time interval.

[0131] Step 2: Based on the operation mode of the distribution network, analyze the topology, power flow, voltage and other constraints of the distribution network reconstruction, and establish a distribution network reconstruction model with minimum network loss and voltage deviation as the objective function. The main implementation steps are as follows:

[0132] (1) Analyze the operating characteristics of network distribution network reconstruction and establish the reconstruction goal of minimizing network loss and bus voltage deviation:

[0133] Where: Rated voltage is V N The network loss is P inj The voltage deviation is expressed as the absolute value of the voltage amplitude deviation. calculate.

[0134] (2) Analyze the network topology connection, introduce topology relationship variables, and establish the radial topology connection constraints of the distribution network:

[0135]

[0136]

[0137]

[0138]

[0139] Where: β mn Indicates that if node n is the parent node of node m, then β mn =1, otherwise 0. nm Indicates that if node m is the parent node of node n, then β nm =1, otherwise 0. The substation node is the root node. Except for the root node, all other nodes have only one parent node. N is the set of all distribution buses. N s It is a collection of substation buses.

[0140] (3) Analyze the power balance conditions of distribution network nodes and establish node power balance constraints:

[0141]

[0142]

[0143] Where: PD m and QD m are the active load and reactive load of node m respectively. mn and Q mn is the active power and reactive power of line mn. ENS m This is active load shedding. m is the reactive load shedding ratio.

[0144] (4) Analyze the power flow of the line and establish the active power and reactive power flow constraints on line mn:

[0145]

[0146]

[0147] Where: B l and G l are the conductance and susceptance of line l, is the parallel conductance of line l to ground. Auxiliary variable Indicates the voltage of line l. l and t l are auxiliary variables of line l respectively.

[0148] (5) Analyze the relationship between auxiliary variables and node voltages, and establish auxiliary voltage variable constraints:

[0149]

[0150]

[0151]

[0152] Where: represents the voltage of line l, α l Indicates the connection status of line l during line reconstruction. When line l is connected, α l =1, When line l is disconnected, α l =0,

[0153] (6) Analyze and establish constraints between auxiliary variables and voltage limits:

[0154]

[0155]

[0156]

[0157]

[0158] Where: V n,max and V m,max Represent the maximum voltage of nodes m and n respectively.

[0159] (7) Analyze and establish the current amplitude constraint of the auxiliary variable:

[0160]

[0161] Where: A l ,B l ,C l ,D l is the current amplitude constraint coefficient of the auxiliary variable, I l,max is the maximum current of line 1.

[0162] Step 3: Based on the line connection state variables and line maintenance variables, establish the coupling constraints for the distribution network line maintenance optimization scheduling and distribution network reconstruction. The specific implementation steps are as follows:

[0163] (1) Analyze the relationship between line state variables and maintenance variables, consider the relationship between line maintenance start-stop status and distribution network topology reconstruction, and establish the coupling constraints of distribution network line maintenance optimization scheduling and distribution network reconstruction:

[0164]

[0165]

[0166]

[0167] Where: Y l,t is the open and closed state of line l at time t. l,t and q l,t are the maintenance start and end status indicator variables of line l at time t. l,t represents the connection state of line l at time t during line reconstruction. The coupling constraint ensures that the line connection state must be disconnected if the line is undergoing maintenance. Furthermore, the coupling constraint ensures that the network is only reconstructed at the beginning or end of line maintenance.

[0168] Step 4: Taking the minimum maintenance cost, network loss, and voltage deviation as the objective function, a distribution network reconstruction coordinated maintenance model considering voltage deviation is established. The specific implementation steps are as follows:

[0169] (1) Considering the optimized scheduling of distribution network line maintenance and distribution network reconstruction, a distribution network reconstruction coordinated maintenance model considering voltage deviation is established with the minimum maintenance cost, network loss and voltage deviation as the objective function. The model optimization objectives are as follows:

[0170]

[0171] (2) The model constraints are as follows:

[0172] Maintenance constraints:

[0173]

[0174]

[0175]

[0176]

[0177]

[0178]

[0179]

[0180] Refactoring constraints:

[0181]

[0182]

[0183]

[0184]

[0185]

[0186]

[0187]

[0188]

[0189]

[0190]

[0191]

[0192]

[0193]

[0194]

[0195] Coupling constraints:

[0196]

[0197]

[0198] (3) Assume that Figure 2In the IEEE 33-node system diagram shown, Line 7 is scheduled for maintenance. The maintenance window is the next day, which is 24 hours. This example provides a globally optimal solution for maintenance scheduling and network topology. The maintenance duration is set to 6 hours. In the optimization results obtained in this example, the optimal maintenance time for Line 7 is calculated to be between 11:00 and 16:00. Figure 3 、 Figure 4 、 Figure 5 The reconstructed distribution network models calculated in this embodiment before, during and after maintenance are respectively given.

[0199] (4) Figure 6 Figure 1 shows the voltage deviation at different times under the distribution network reconstruction coordination maintenance model proposed in this embodiment, which considers voltage deviation, and the maintenance scheduling model that does not consider distribution network reconstruction. As can be seen from the figure, the maintenance scheduling model that considers distribution network reconstruction can reduce voltage deviation by approximately 13.3%. Figure 7 This figure shows network losses at different times under the coordinated maintenance model for distribution network reconstruction that considers voltage deviations, as proposed by the present invention, and under a maintenance scheduling model that doesn't consider distribution network reconstruction. In the time intervals of 0:00-10:00 and 22:00-24:00, the difference in network losses between the maintenance scheduling model with and without considering distribution network reconstruction is minimal. In the time interval of 10:00-22:00, the maintenance scheduling model that considers distribution network reconstruction can reduce network losses by approximately 16.7%.

[0200] Through the description of the above implementation methods, technical personnel in the relevant field can understand that for the convenience and simplicity of description, only the division of the above-mentioned functional modules is used as an example. In actual applications, the above-mentioned functions can be distributed and completed by different functional modules as needed, that is, the internal structure of the specific device can be divided into different functional modules to complete all or part of the functions described above.

[0201] If the integrated unit is implemented in the form of a software functional unit and sold or used as an independent product, it can be stored in a readable storage medium. Based on this understanding, the technical solution of the embodiment of the present application is essentially or the part that contributes to the prior art or all or part of the technical solution can be embodied in the form of a software product, which is stored in a storage medium and includes several instructions for enabling a device (which can be a single-chip microcomputer, chip, etc.) or a processor to execute all or part of the steps of the various embodiments of the present application. The aforementioned storage medium includes various media that can store program codes, such as a USB flash drive, a mobile hard disk, a read-only memory (ROM), a random access memory (RAM), a magnetic disk or an optical disk.

[0202] The above content is merely a specific embodiment of the present application, but the scope of protection of the present application is not limited thereto. Any changes or substitutions that can be easily conceived by a person skilled in the art within the technical scope disclosed in this application should be included in the scope of protection of the present application. Therefore, the scope of protection of the present application should be based on the scope of protection of the claims.

Claims

1. A distribution network reconstruction and coordinated maintenance model considering voltage deviation is characterized by: The distribution network reconstruction coordinated maintenance model is used to find the global optimal solution for maintenance scheduling and network topology. The distribution network reconstruction coordinated maintenance model is established through the following steps: S01: Establish a model for optimizing the maintenance scheduling of distribution network lines based on the maintenance costs affected by human resources and load conditions in different time periods; S02: Based on the operation mode of the distribution network, analyze the topology, power flow, and voltage constraints of the distribution network reconstruction, and establish a distribution network reconstruction model with minimum network loss and voltage deviation as the objective function; S03: Based on the line connection state variables and line maintenance variables, establish the coupling constraints of the distribution network line maintenance optimization scheduling and distribution network reconstruction; S04: Taking the minimum maintenance cost, network loss and voltage deviation as the objective function, a distribution network reconstruction coordinated maintenance model considering voltage deviation is established; Step S04 includes: S41: A distribution network reconstruction and coordinated maintenance model considering voltage deviation is established. The model optimization objectives are as follows: S42: The model constraints are as follows: Maintenance constraints: Refactoring constraints: Coupling constraints: ； Where: is the maintenance cost of line l at time t, is the open and closed state of line l at time t; when the line is closed normally =1, when the line is disconnected for maintenance =0; is the required maintenance duration of line l, It is the horizontal axis coordinate of maintenance scheduling; It is the allowable maintenance time window given by the system operator; and are the maintenance start and end status indicator variables of line l at time t, respectively. =1, otherwise 0, when the maintenance is completed =1, otherwise 0; is the minimum maintenance duration, is the maintenance interval; the rated voltage is ; The network loss is The voltage deviation is expressed as the absolute value of the voltage amplitude deviation. calculate; Indicates that if node n is the parent node of node m, then =1, otherwise 0; If node m is the parent node of node n, then =1, otherwise 0; the substation node is the root node; except the root node, all other nodes have only one parent node; N is the set of all distribution buses; It is a collection of substation buses; and are the active load and reactive load of node m respectively; and are the active and reactive powers of line mn; To reduce active load; is the reactive load shedding ratio; and are the conductance and susceptance of line l, is the parallel conductance of line l to ground; auxiliary variable Indicates the voltage of line l; and are the auxiliary variables of line l; represents the voltage of line l, ; Indicates the connection status of line l during line reconstruction; when line l is connected, =1, = ; When line l is disconnected, =0, = =0; and Represent the maximum voltage of nodes m and n respectively; , , , is the current amplitude constraint coefficient of the auxiliary variable, is the maximum current of line l; is the open and closed state of line l at time t; and are the maintenance start and end status indicator variables of line l at time t respectively; represents the connection state of line l at time t during line reconstruction; the coupling constraint restricts the line connection state to be disconnected if the line is under maintenance; at the same time, the coupling constraint also ensures that the network is only reconstructed at the beginning or end of line maintenance.

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