Power distribution network fault handling method based on power distribution terminal differential time optimization

Abstract

The invention provides a power distribution network fault handling method based on power distribution terminal differential time optimization. Establishing a 10kV hand-in-hand power distribution network simulation model; designing self-adaptive comprehensive terminal action logic and relay protection level difference time cooperation; a simulation fault set containing multiple fault types and multiple fault sites is constructed, and the action sequence of each power distribution terminal and relay protection under different stage difference setting conditions and the power supply recovery strategy of a non-fault area are studied; and a water wave optimization algorithm is used to carry out parameter optimization on the setting scheme of time level difference cooperation, and comprehensive evaluation is carried out on the optimal scheme under all fault conditions, so that a set of power distribution network optimal fault handling method based on power distribution terminal level difference time optimization is obtained. The problems of override tripping, wrong tripping and the like possibly occurring under the cooperation of the existing fixed time level difference can be solved, and the power supply reliability of a power distribution network system can be improved.

Description

Technical Field

[0001] The present invention relates to the technical field of power distribution networks, and in particular to a method for handling power distribution network faults based on power distribution terminal differential time optimization. Background Art

[0002] To improve the reliability of distribution network power supply, many medium and low voltage overhead distribution lines have been installed with distribution terminals. Adaptive integrated terminals, as local distribution terminals, eliminate the need for communication with a master station, significantly reducing investment costs and leading to their widespread adoption. The widespread availability of these terminals allows for rapid fault removal and isolation, quickly restoring power to loads in non-faulty areas after a distribution network fault. Furthermore, the introduction of differential protection technology, in conjunction with relay protection, has reduced power outage losses caused by distribution network faults. However, traditional differential protection has a relatively fixed timing. In the context of new power system development, overtripping or refusal to trip are common, reducing system power supply reliability and making it difficult to maintain system stability. Summary of the Invention

[0003] To address these issues, the present invention proposes a distribution network fault handling method based on distribution terminal step-time optimization. This method simulates faults using multiple time-step-time conditions in an established distribution network simulation system and uses a water wave optimization algorithm to minimize load outage losses, thereby finding the optimal step-time.

[0004] Specifically, the present invention proposes a distribution network fault handling method based on distribution terminal differential time optimization. By performing multi-location fault simulation on a feeder automation system equipped with relay protection and distribution terminals, the system load power outage losses under different fault locations and different time differential coordination are analyzed. Under the premise that the terminal layout location is known, a set of optimal time differential coordination schemes are obtained to reduce load power outage losses.

[0005] Specifically, the method comprises the following steps:

[0006] S1. Use power system simulation software to build a hand-in-hand 10kV distribution network system with closed-loop design and open-loop operation;

[0007] S2. Design a set of protection devices in the constructed distribution network simulation system. The distribution terminal uses an adaptive integrated type, and the relay protection is designed as differential coordination.

[0008] S3. Comprehensively consider the layout principles of distribution terminals and relay protection devices and configure protection in the established 10kV distribution network system;

[0009] S4. Taking the comprehensive load power outage loss cost as the objective function and the maximum fault clearing time of the substation outlet circuit breaker as the constraint condition, a distribution terminal differential time optimization model is constructed based on the water wave optimization algorithm to solve the optimal differential configuration plan, thereby obtaining a fault handling method based on the optimal differential plan.

[0010] Preferably, the step S1 includes:

[0011] Based on the five elements of distribution network modeling: electrical model, load model, fault simulation model, protection and control model, and system stability model, a 10kV hand-in-hand distribution network is established.

[0012] Preferably, in step S2, the action logic of the adaptive integrated feeder automation includes a data acquisition and processing module, a closing delay module, a closing lock module, and an opening and closing judgment module; wherein the data acquisition and processing module includes: a main power supply side voltage transformer module, a tie switch side voltage transformer and a fault current memory module; the closing delay module includes: a short delay and a long delay closing control module; the closing lock module includes an X delay / Y delay logic lock control module, which performs forward incoming call lock and reverse incoming call lock judgment; the opening and closing judgment module includes: closing and opening judgment.

[0013] Preferably, the voltage transformer module on the main power supply side includes a voltage transformer, a voltage measurement module, a voltage loss detection module and a voltage detection module; the fault current memory module includes a current transformer module, a current measurement module and an overcurrent detection module at the switch; the voltage transformer on the contact switch side includes a voltage transformer, a voltage measurement module, a voltage detection module and a long delay module.

[0014] Preferably, step S3 includes:

[0015] Design a set of protection devices in the constructed distribution network simulation system. Use adaptive integrated type for distribution terminals, and design differential coordination for relay protection. Consider the layout principles of distribution terminals and relay protection devices, and configure protection in the constructed 10kV distribution network system.

[0016] For nodes with more feeder branches and nodes with dense feeder branch load distribution in the simulation model, adaptive integrated terminals are configured. For nodes with fewer feeder branches or branches with less end load, relay protection with reclosing function is configured.

[0017] Preferably, step S4 includes:

[0018] Taking the comprehensive load outage loss cost as the objective function and the maximum clearing time of the substation outlet circuit breaker fault as the constraint condition, the optimal differential configuration scheme is solved based on the water wave optimization algorithm;

[0019] Random simulation of fault types and fault locations is performed on each scheme under each differential time configuration, and the comprehensive load power outage loss cost under the scheme is calculated and recorded. After all schemes have been iterated, they are sorted according to the cost to find the optimal differential coordination scheme, thereby obtaining a distribution network fault handling method with optimized differential time of distribution terminals.

[0020] The present invention constructs a simulated fault set containing multiple fault types and multiple fault locations, studies the action sequence of each distribution terminal and relay protection under different differential settings, and the power supply restoration strategy for non-fault areas; uses the water wave optimization algorithm to optimize the parameters of the time differential coordination setting scheme, and obtains a set of distribution network optimal fault handling methods based on distribution terminal differential time optimization, which can solve the problems of over-tripping and false tripping that may occur under the existing fixed time differential coordination, and help improve the power supply reliability of the distribution network system. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] The drawings described herein are used to provide a further understanding of the embodiments of the present invention, constitute a part of this application, and do not constitute a limitation of the embodiments of the present invention;

[0022] Figure 1 A flowchart of the method of the present invention;

[0023] Figure 2 A topological diagram of a hand-in-hand 10kV distribution network constructed by the present invention;

[0024] FIG3 is a diagram of the power distribution terminal and relay protection operation logic constructed by the present invention, FIG3(a) is the adaptive integrated FA logic, and FIG3(b) is the differential protection logic;

[0025] Figure 4 shows the distribution network fault handling process based on the differential coordination of distribution terminals;

[0026] Figure 5 This is a specific flow chart of solving the optimal step time using the water wave optimization algorithm according to a preferred embodiment of the present invention. DETAILED DESCRIPTION

[0027] The following embodiments of the present invention are described in further detail with reference to the accompanying drawings and examples. The following examples are used to illustrate the present invention but are not intended to limit the scope of the present invention.

[0028] The present invention proposes a distribution network fault handling method based on distribution terminal differential time optimization. By performing multi-location fault simulation on a feeder automation system equipped with relay protection and distribution terminals, the system load power outage losses under different fault locations and different time differential coordination are analyzed. Under the premise that the terminal layout location is known, a set of optimal time differential coordination schemes are obtained to minimize the load power outage losses.

[0029] See Figure 1 , the method specifically comprises the following steps:

[0030] S1. Based on the five elements of distribution network system modeling, a typical hand-in-hand 10kV distribution network system is built using power system simulation software, with closed-loop design and open-loop operation.

[0031] Based on the five elements of distribution network modeling: electrical model, load model, fault simulation model, protection and control model, and system stability model, a 10kV hand-in-hand distribution network is established.

[0032] See Figure 2 The established 10kV hand-in-hand distribution network simulation model mainly includes four parts: 110kV substation, 10kV trunk feeder, 0.4kV branch feeder, tie switch and 10kV backup power supply.

[0033] The substation outlet voltage is selected as 110kV, which is stepped down to 10kV by the main transformer. The main transformer outlet is connected to the main circuit breaker. The electrical parameters are replaced by the overhead line model, and the line type is LGJ-50. The 10kV feeder branch is connected to the load through a step-down transformer. The load voltage level is 0.4kV, and the load type is a mixed model. Most parameters are set to the KW level to simulate household electricity consumption, and a small number of parameters are set to the MW level to simulate factory electricity consumption. A section switch is set at the branch point of the 10kV feeder, and a boundary switch is set on the load branch. A connecting switch is set at the end of the feeder, which is connected to the 10kV backup power supply. The switch is in the open state during normal operation. When a short circuit fault occurs, the switch is closed to realize load transfer.

[0034] S2. Design a set of protection devices in the constructed distribution network simulation system. The distribution terminal uses an adaptive integrated type, and the relay protection is designed as a differential coordination.

[0035] Referring to Figure 3(a), the adaptive integrated feeder automation FA action logic constructed in this paper has four main functional modules: data acquisition and processing module, closing delay module, closing lockout module, and opening and closing judgment module. Among them, the data acquisition and processing module includes: the main power side voltage transformer module, the interconnecting switch side voltage transformer and the fault current memory module. The main power side voltage transformer module includes the voltage transformer, voltage measurement module, undervoltage detection module and pressure detection module; the fault current memory module includes the current transformer module at the switch, current measurement module and overcurrent detection module; the interconnecting switch side voltage transformer includes the voltage transformer, voltage measurement module, pressure detection module and long delay module;

[0036] The closing delay module includes: short delay and long delay closing control modules; the closing lock module includes X delay / Y delay logic lock control module, which performs forward power lock and reverse power lock judgment; the opening and closing judgment module includes: closing and opening judgment.

[0037] Referring to Figure 3(b), the differential protection action logic implemented in this invention consists of three main functional modules: a data acquisition module, a secondary reclosing / lockout determination module, and a trip determination module. The data acquisition module includes the current transformer at the main circuit breaker, a current measurement module, and overcurrent stage I and stage III detection modules.

[0038] The secondary reclosing lockout / determination module includes: an overcurrent delay selection module, a reclosing counting module, a reclosing lockout module, a closing logic determination module and a closing module; the overcurrent delay selection module is composed of three delay modules, and the reclosing counting module is composed of two output holding modules.

[0039] The switch tripping judgment module includes: a delay module and a tripping logic judgment module.

[0040] Specifically, the main circuit breaker has two processing modes: instantaneous overcurrent protection and delayed overcurrent protection. In addition, it is equipped with two delayed reclosing functions. The first delayed reclosing is used to deal with instantaneous faults, and the second delayed reclosing is used to restore power to non-fault areas.

[0041] The instantaneous overcurrent protection is to ensure selectivity, and its protection range does not exceed the head end of the lower line. Its setting value I set I The calculation formula is as follows:

[0042]

[0043] where K rel I is the protection factor of current segment I; B_max is the maximum short-circuit current at the end of the line at this level; ZSmin is the system impedance under the maximum operating mode, Z A-B The impedance of the line where the main circuit breaker is located.

[0044] For delayed overcurrent protection, the parameter setting is related to the operating mechanism used by the circuit breaker. Currently, in order to reduce the impact of short-circuit current on the system, the 10kV side feeder is required to cut off the fault current within 0.5s.

[0045] For switches using a spring-energy storage operating mechanism, the mechanical action time is generally 30ms, the arc extinction time is 10ms, and the inherent protection response time is approximately 30ms. This means that the total tripping time of a spring-operated circuit breaker is approximately 100ms. Using three-level time differential protection, the time margin is approximately 200ms. For circuit breakers using a permanent magnet operating mechanism, the total action time is approximately 10ms. Using three-level time differential protection, the time margin is 250-300ms. The time delay of the main circuit breaker is currently set to Δt3.

[0046] According to the two fault clearing modes of the main circuit breaker, when the fault is within the protection range of section I, the main circuit breaker will instantly clear the fault. When the fault is outside the range of section I, selective clearing can be achieved according to the coordination of time difference, that is, the protection range of current I is l min This is the area where the differential fit fails, and the specific calculation formula is as follows:

[0047]

[0048] Among them I Kmin (2) is the minimum short-circuit current when a two-phase short circuit occurs at the end of the line, Z Smax is the system impedance in the minimum operating mode.

[0049] For the section switch, if the device used is an adaptive integrated distribution terminal, its functions include: opening due to loss of voltage, delayed closing due to incoming power, closing due to incoming power if the closing does not maintain the Y time limit, and closing due to incoming power if the incoming power does not maintain the X time limit. If relay protection is used, its functions include: opening due to overcurrent delay, with the delay set to Δt2, and single reclosing.

[0050] For the boundary switch, when the terminal is used, the function is the same as that of the section switch, and the relay protection configuration used is: instantaneous overcurrent protection and single reclosing.

[0051] For the interconnecting switch, three remote terminals are configured, which have the following functions: it is in the disconnected state under normal circumstances, automatically closes when the terminal tower loses pressure for a long time to realize load transfer, and locks and closes when there is a short-term power supply.

[0052] S3. Comprehensively consider the layout principles of distribution terminals and relay protection devices and configure protection within the established 10kV distribution network system. For nodes with a large number of feeder branches and densely distributed loads on feeder branches in the simulation model, deploy adaptive integrated terminals. For nodes with fewer feeder branches or branches with less load at the end, deploy relay protection with reclosing capabilities.

[0053] S4. Using the comprehensive load outage loss cost as the objective function and the substation fault clearing time as the constraint, specifically the maximum clearing time of the substation outlet circuit breaker fault, a distribution terminal differential time optimization model is constructed based on the water wave optimization algorithm. The optimal differential configuration solution is solved, thereby obtaining a fault handling method based on the optimal differential solution.

[0054] Refer to Figure 4. In order to show the distribution network fault handling method based on distribution terminals and differential protection, the FTU and RP configurations of the switch configuration have been omitted. For specific configurations, refer to Figure 2 The area within the dotted box in the figure represents the instantaneous current quick-break protection range of the main circuit breaker CB, and the area outside the dotted box is the executable area of the differential protection. After the primary and secondary sides of the distribution network are built, the fault module is added. The specific fault handling method is as follows:

[0055] The fault in Figure 4(a) is within the protection range of the main circuit breaker's current stage I and is a permanent fault. Therefore, the main circuit breaker clears the short-circuit fault in zero time. The specific fault handling process is as follows:

[0056] 1) The main circuit breaker CB operates with zero time limit to cut off the circuit breaker current.

[0057] 2) The isolating switches FS1 and FS2 will open due to loss of voltage due to the installation of distribution terminals.

[0058] 3) The main circuit breaker CB is reclosed with a time delay. The disconnector FS1 is located upstream of the fault and has a fault current memory, so it closes with a short delay.

[0059] 4) The disconnector FS1 is closed at the fault point and the main circuit breaker CB is opened again due to overcurrent.

[0060] 5) Disconnector FS1 opens again due to voltage loss, and the forward power closing is blocked because the closing does not last for the Y time limit. Disconnector FS2 blocks the reverse power closing because the voltage signal does not last for the X time limit. The fault is automatically located between disconnectors FS1 and FS2.

[0061] 6) The main circuit breaker CB is reclosed for the second time, restoring power to the load lines L1, L2, and L3. The tie switch detects that the busbar Bus2 has lost voltage for a long time and automatically closes, restoring power to the load line L6.

[0062] The fault in Figure 4(b) is outside the protection range of the main circuit breaker's current stage I and is a permanent fault. The specific fault handling process is as follows:

[0063] 1) Both the main circuit breaker CB and the switch S4 detect overcurrent signals. The switch S4 delays Δt2 to cut off the short-circuit current. The main circuit breaker CB does not operate because the fault has been cut off within the delay Δt1.

[0064] 2) The isolating switch FS2 opens due to loss of pressure.

[0065] 3) Switch S4 is reclosed once after a delay.

[0066] 4) Switch S4 trips again because it is closed at the fault point, and disconnector FS2 blocks the reverse power closing because the voltage power signal does not maintain the X time limit.

[0067] 5) The tie switch LS detects a long-term voltage loss on Bus 2 and automatically closes, restoring power to the load line L6.

[0068] See Figure 5 ,For the established 10kV distribution network simulation model, a set containing all fault types and fault locations is set with reference to the known line data, denoted as φ fault,p2 .

[0069] The delayed overcurrent protection of the main circuit breaker is used as the third-level protection, with a delay of Δt3; the relay protection on the trunk feeder is used as the second-level protection, with a delay of Δt2; the relay protection on the user branch is used as the first-level protection, with a delay of Δt1. Considering the requirements of differential coordination and the maximum fault clearing time of the main circuit breaker, the three-level delay must meet the following conditions:

[0070] Δt1<Δt2<Δt3

[0071] Δt1+Δt2+Δt3=t max -t CB

[0072] Among them, t max is the maximum fault clearing time of the substation outlet circuit breaker, t CB is the action time corresponding to the circuit breaker of different operating mechanisms. Generally speaking, the first-level protection is configured with instantaneous overcurrent, that is, Δt1=0, and an initial population is constructed using the water wave optimization algorithm. The initial position of the population is set to the second-level protection delay Δt2, and the third-level protection delay is t max -t CB -t2

[0073] For each differential time configuration, random simulations of fault types and locations are performed. The combined load outage cost under each configuration is calculated and recorded. After all the configurations have been iterated, they are ranked by cost to determine the optimal differential coordination scheme. This results in a distribution network fault handling method that optimizes the differential time at the distribution terminal.

[0074] The specific calculation formula for the fee is as follows:

[0075] 1) Load power outage loss costs in the fault area

[0076] When considering the coordination between relay protection and distribution terminals, the load outage time in the fault area is the sum of the fault location time and the fault repair time. When line i fails, the outage time of load j in the fault area is calculated as follows:

[0077] t f_loss,i,j =t loc i +t rep i

[0078] Where: t loc i is the fault location time when a short circuit fault occurs on line i, is the fault duration of line i. Considering that the fault repair time is usually in the order of hours, it can be approximately considered that the power outage time of line i is equal to the average duration of permanent faults of the line t f_continue ,Right now:

[0079] t f_loss,i,j =t f_continue

[0080] When a permanent short circuit occurs on line i, the total load power outage loss in the fault area is:

[0081]

[0082] The total power outage loss cost is:

[0083]

[0084] Where: W f_loss.i is the total load loss in the fault area when a permanent fault occurs on line i; C kWh is the unit electricity price of the system; F is the average annual number of feeder failures in the distribution area; line i is the line length of the fault feeder i; φ k is the set of all feeder segments; T is the evaluation period, in years; φ fault,i,j is the set of all load numbers in the fault area when feeder segment i fails; Pj is the average active power of the load numbered j in the fault area.

[0085] 2) Load power outage loss costs in non-fault areas

[0086] When considering the coordination between relay protection and distribution terminals, the load outage time in the non-fault area is the sum of the fault location time, fault isolation time, and power supply restoration time. When line i fails, the power outage time of load j in the non-fault area is calculated as follows:

[0087] t nf_loss,i,j =t loc i +t iso i,j +t res i,j

[0088] Where: t iso i,j is the isolation time experienced by load j when a short circuit fault occurs in line i, t res i,j It is the time for the CB secondary reclosing to restore power supply or the time for the tie switch to transfer load.

[0089] When a permanent short circuit fault occurs on line i, the total load power outage loss in the non-fault area is:

[0090]

[0091] The total power outage loss cost is:

[0092]

[0093] Where: W nf_loss,i is the total load loss in the non-fault area when a permanent fault occurs on line i, φ n_fault,i,j is the set of numbers of loads j in the non-fault area when line i fails.

[0094] That is, when line i fails, the total power outage loss cost of the system is expressed as:

[0095] C loss =C fault_loss +C n_fault_loss

[0096] Among them, the load power outage time in the non-fault area is closely related to the setting time of the step time Δt, and needs to be specifically calculated according to the voltage output signal during the simulation process.

[0097] In summary, the objective function expression of the water wave optimization algorithm is:

[0098] minCfault_loss +C n_fault_loss

[0099] The initial population size is N, the dimension is D, the water wave amplitude A0, wave velocity v, attenuation coefficient λ, and maximum number of iterations G are initialized, and the position parameter x of the water wave is initialized to the set time Δt2 of the secondary protection delay.

[0100] Set the boundaries of the water wave parameters. Since there are many setting schemes for differential coordination, a wave speed that is too small may not converge to the optimal value. Therefore, the speed boundary is set as follows:

[0101] -10≤v j ≤10

[0102] The initial position parameter Δt2 of the water wave is set to a certain boundary. The circuit breaker operation time selected in this embodiment is about 0.1s, which is consistent with the characteristics of the spring operating mechanism. Therefore, the margin of the differential protection is about 400ms. Considering that the first level protection does not require an overcurrent setting, the particle position initialization boundary is:

[0103] 0<x j =Δt2<200ms

[0104] The fitness calculation formula for each initial individual is:

[0105] fitness=-(C fault_loss +C n_fault_loss )

[0106] Calculate the new position of the water wave during the iteration:

[0107] x j (t+1)=x j (t)+α×A0e -λt ×v×d

[0108] where x j (t+1) is the position of the water wave numbered j in the tth generation, α is a random number in the range of [-1,1], and d is the randomly generated direction.

[0109] Calculate the fitness of the new position of the water wave, and update the position if the fitness is better

[0110] fitness(t+1)>fitness(t)

[0111] When the number of iterations reaches the preset value, the minimum objective function value is output, along with the corresponding secondary protection delay parameter Δt2. The corresponding protection delays Δt1, Δt2, and Δt3 for each level under this scheme represent the optimal differential protection configuration when the terminal and protection locations are known. The entire fault handling process under this optimal scheme represents a distribution network fault handling method based on differential time optimization at distribution terminals.

[0112] The above are only preferred embodiments of the present invention, but do not limit the scope of the patent of the present invention. Although the present invention has been described in detail with reference to the above embodiments, those skilled in the art can still modify the technical solutions described in the above specific embodiments or replace some of the technical features therein with equivalents. Any equivalent structure made by using the contents of the present invention specification and drawings, directly or indirectly applied to other related technical fields, is also within the scope of protection of the patent of the present invention.

Claims

1. A distribution network fault handling method based on distribution terminal differential time optimization, characterized in that: By conducting multi-location fault simulation on the feeder automation system equipped with relay protection and distribution terminals, the system load power outage losses under different fault locations and different time difference coordination are analyzed. Under the premise that the terminal layout location is known, a set of optimal time difference coordination schemes are obtained to reduce load power outage losses.

2. The method according to claim 1, characterized in that The method comprises: S1. Use power system simulation software to build a hand-in-hand 10kV distribution network system with closed-loop design and open-loop operation; S2. Design a set of protection devices in the constructed distribution network simulation system. The distribution terminal uses an adaptive integrated type, and the relay protection is designed as differential coordination. S3. Comprehensively consider the layout principles of distribution terminals and relay protection devices and configure protection in the established 10kV distribution network system; S4. Taking the comprehensive load power outage loss cost as the objective function and the maximum fault clearing time of the substation outlet circuit breaker as the constraint condition, a distribution terminal differential time optimization model is constructed based on the water wave optimization algorithm to solve the optimal differential configuration plan, thereby obtaining a fault handling method based on the optimal differential plan.

3. The method according to claim 2, characterized in that The step S1 comprises: Based on the five elements of distribution network modeling: electrical model, load model, fault simulation model, protection and control model, and system stability model, a 10kV hand-in-hand distribution network is established.

4. The method according to claim 3, characterized in that In step S2, the action logic of the adaptive integrated feeder automation includes a data acquisition and processing module, a closing delay module, a closing lock module, and an opening and closing judgment module; wherein the data acquisition and processing module includes: a main power supply side voltage transformer module, a tie switch side voltage transformer and a fault current memory module; the closing delay module includes: a short delay and a long delay closing control module; the closing lock module includes an X delay / Y delay logic lock control module to perform forward incoming call lockout and reverse incoming call lockout judgment; and the opening and closing judgment module includes: closing and opening judgment.

5. The method according to claim 4, wherein the voltage transformer module on the main power supply side includes a voltage transformer, a voltage measurement module, a voltage loss detection module and a voltage detection module; the fault current memory module includes a current transformer module, a current measurement module and an overcurrent detection module at the switch; and the voltage transformer on the tie switch side includes a voltage transformer, a voltage measurement module, a voltage detection module and a long delay module.

6. The method according to claim 5, characterized in that The step S3 comprises: Design a set of protection devices in the constructed distribution network simulation system. Use adaptive integrated type for distribution terminals, and design differential coordination for relay protection. Consider the layout principles of distribution terminals and relay protection devices, and configure protection in the constructed 10kV distribution network system. For nodes with more feeder branches and nodes with dense feeder branch load distribution in the simulation model, adaptive integrated terminals are configured. For nodes with fewer feeder branches or branches with less end load, relay protection with reclosing function is configured.

7. The method according to claim 6, characterized in that The step S4 comprises: Taking the comprehensive load outage loss cost as the objective function and the maximum clearing time of the substation outlet circuit breaker fault as the constraint condition, the optimal differential configuration scheme is solved based on the water wave optimization algorithm; Random simulation of fault types and fault locations is performed on each scheme under each differential time configuration, and the comprehensive load power outage loss cost under the scheme is calculated and recorded. After all schemes have been iterated, they are sorted according to the cost to find the optimal differential coordination scheme, thereby obtaining a distribution network fault handling method with optimized differential time of distribution terminals.

Images