A distribution network fault recovery method based on energy storage flexible switch

Abstract

The present invention discloses a distribution network fault recovery method based on an energy storage type flexible switch, including: S1, assessing the damage risk and determining the installation position of the energy storage type flexible switch according to the historical data of landslide disasters in the area where the distribution area is located; S2, calculating and determining the control strategy of the energy storage type flexible switch according to the annual cycle life and life cost of the battery of the energy storage type flexible switch, smoothing power fluctuations by storing and releasing electric energy, and reducing the uncertainty of load demand; S3, with the goal of minimizing the commissioning cost, calculating and outputting the power output value of the distributed power source and the capacity value that maximizes the service life of the energy storage type flexible switch. The installation position of the energy storage type flexible switch is determined by assessing the damage risk of landslides, calculating the annual cycle life and life cost of the battery, determining the usage method, and finally combining the distributed power source to minimize the commissioning cost to control the output, thereby improving the power supply recovery efficiency and power supply quality.

Description

Technical Field

[0001] The present invention relates to the technical field of power distribution fault restoration, and in particular to a distribution network fault restoration method based on energy storage type flexible switches. Background Art

[0002] Since the existing energy supply for factories and households mainly relies on electricity supply, the safe and reliable operation of the distribution network is the basis for ensuring the normal operation of society. Once the distribution network fails, it will cause power outages and cause economic losses to users and power supply companies, so the power supply recovery capability of the distribution network is crucial to the reliability of power supply.

[0003] The power supply restoration of traditional distribution networks is mainly achieved through distributed power sources such as wind power and photovoltaics and relay protection devices. However, after extreme natural events, the volatility of new energy makes it impossible for the faulty substation to obtain reliable power supply. The relay protection device responds slowly and will cut off the load near the fault point, causing unnecessary losses.

[0004] Therefore, a flexible and efficient fault recovery method is needed to ensure the safe operation of the distribution network. Summary of the invention

[0005] The purpose of the present invention is to provide a distribution network fault recovery method based on energy storage type flexible switches, so as to improve the fault recovery efficiency and power supply quality of the distribution network.

[0006] In order to solve the above technical problems, an embodiment of the present invention provides a distribution network fault recovery method based on an energy storage type flexible switch, comprising:

[0007] S1, based on the historical data of landslide disasters in the distribution area, assess the landslide damage risk and determine the installation location of the energy storage flexible switch;

[0008] S2, calculating and determining the control strategy of the energy storage type flexible switch based on the annual cycle life and life cost of the battery of the energy storage type flexible switch, smoothing power fluctuations and reducing load demand uncertainty by storing and releasing electric energy;

[0009] S3, with the goal of minimizing the commissioning cost, calculates and outputs the power output value of the distributed power supply and the capacity value that maximizes the service life of the energy storage flexible switch.

[0010] Wherein, the S1 includes:

[0011] Based on the regression method, the monotonic function m representing the hazard intensity of each substation area is obtained from the historical data of landslides in the distribution substation area. i , the landslide historical data include geographical location, soil type, and geological characteristics;

[0012] Determine the corresponding hazard weight ω according to the economic loss of the power distribution area after the disaster i , calculate and obtain the landslide damage risk index S l for:

[0013]

[0014] where i l is the number of stations, n l is the total number of areas;

[0015] For S l Normalize it and take its value in the interval [0,1], S l The larger the size, the greater the damage caused by landslides;

[0016] Set when S l When it is greater than the set risk threshold, it indicates that the risk of landslide damage is high, and it is necessary to install the energy storage flexible switch to restore power supply after the disaster.

[0017] Wherein, the S1 includes:

[0018] According to the historical landslide disaster data and geological information of the distribution area, the probability of landslide under different slopes and soil conditions is calculated, and the hazard intensity monotonic function is fitted based on the regression method. The landslide damage risk index is obtained based on the post-disaster cost loss and the installation location of the energy storage soft switch is determined.

[0019] Wherein, the S1 also includes:

[0020] The risk threshold is set.

[0021] Wherein, the S2 includes:

[0022] The energy storage type flexible switch control model is established by calculating and based on the charge and discharge cycle process of the energy storage type flexible switch, the discharge depth at the moment before charging, the battery cycle life, and the equivalent full cycle number at 100% discharge depth converted from each discharge cycle of different depths according to the energy storage life:

[0023] According to the energy storage type flexible switch control model, the annual cycle life of the battery T is calculated. i,cyc and life cycle cost C i,ES .

[0024] Wherein, the S2 includes:

[0025] The charge-discharge cycle process is a charge-discharge cycle that occurs when the energy storage type flexible switch changes from a discharge process to a charging process:

[0026]

[0027] in is a 0-1 variable. When the energy storage state is from charging to discharging, In other cases

[0028] The discharge depth at the moment before charging is the discharge depth at the moment before charging. Represents the battery cycle discharge depth

[0029]

[0030]

[0031] Calculate the battery cycle life include:

[0032]

[0033] Where N0 is the number of cycles when the battery reaches the end of its life at 100% discharge depth, k p is the curve fitting parameter, with a value between 1.1 and 2.1;

[0034] The equivalent full cycle number is calculated by converting the energy storage life into the equivalent full cycle number at 100% discharge depth at each discharge cycle of different depths, where the daily equivalent full cycle number is N i,eq :

[0035]

[0036] Where S is the number of clustered scenes;

[0037] Calculate the annual cycle life of the battery T i,cyc and life cycle cost C i,ES for

[0038] T i,cyc =N0 / (365·N i,eq ) (7),

[0039]

[0040] Among them, C i,inv,ES is the battery investment cost without considering the battery life, and r is the discount rate.

[0041] Wherein, the S3 includes:

[0042] S31, through convex relaxation or large M method, linearization of objective function and constraint condition calculation and control, ensure that the power output and energy storage type flexible switch configuration range can make the model have a feasible solution;

[0043] S32, controlling the distributed power source and the energy storage soft switch to restore power supply to the disaster-stricken area, and obtaining the minimum distributed power source output and energy storage soft switch capacity investment that can meet fault recovery by minimizing the commissioning cost of the fault recovery equipment.

[0044] Wherein, the S32 includes:

[0045] Based on the condition that the operation cost of power supply equipment that meets the post-disaster power supply demand is the minimum, the objective function is calculated as:

[0046]

[0047]

[0048] where c DG , c p , c DC are the unit power investment costs of distributed power supply, converter and DC-DC converter respectively; r is the discount rate; P DG,t P is the active power output of distributed power source; L,t Power loss for operation; is the line loss power; They are the power losses of two converters of energy storage soft switch; is the power loss of the DC-DC converter; x i ,x j ,y i are the planned capacities of VSC and DC-DC at nodes i and j of intelligent energy storage soft switches respectively; Ω l ,Ω SOP-ES ,Ω ES They are respectively the line, the energy storage soft switch, and the battery node set, which need to satisfy the power balance equation, the upper and lower limits of the energy storage charge state, the energy storage charging and discharging constraints, the battery power timing equation, the battery scheduling cycle charge state equation, the power flow equation, the distributed power supply power constraints and the power grid operation safety constraints.

[0049] The distribution network fault recovery method based on the energy storage type flexible switch provided in the embodiment of the present invention has the following advantages compared with the prior art:

[0050] The distribution network fault recovery method based on energy storage flexible switches provided in the embodiment of the present invention determines the installation location of the energy storage flexible switch by assessing the risk of landslide damage, calculates the annual cycle life and life cost of the battery, determines the usage method, and finally combines the distributed power supply to minimize the operation cost to control the output, thereby improving the power supply recovery efficiency and power supply quality. BRIEF DESCRIPTION OF THE DRAWINGS

[0051] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0052] Figure 1 A schematic diagram of a specific implementation of a distribution network fault recovery method based on an energy storage type flexible switch provided in an embodiment of the present invention;

[0053] Figure 2 A schematic flow chart of step S3 in a specific implementation of a distribution network fault recovery method based on an energy storage type flexible switch provided in an embodiment of the present invention. DETAILED DESCRIPTION

[0054] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0055] Please refer to Figure 1-2 , Figure 1 A schematic diagram of a specific implementation of a distribution network fault recovery method based on an energy storage type flexible switch provided in an embodiment of the present invention; Figure 2 A schematic flow chart of step S3 in a specific implementation of a distribution network fault recovery method based on an energy storage type flexible switch provided in an embodiment of the present invention.

[0056] In a specific implementation, the distribution network fault recovery method based on the energy storage type flexible switch includes:

[0057] S1, based on the historical data of landslide disasters in the distribution area, assess the landslide damage risk and determine the installation location of the energy storage flexible switch;

[0058] S2, calculating and determining the control strategy of the energy storage type flexible switch based on the annual cycle life and life cost of the battery of the energy storage type flexible switch, smoothing power fluctuations and reducing load demand uncertainty by storing and releasing electric energy;

[0059] S3, with the goal of minimizing the commissioning cost, calculates and outputs the power output value of the distributed power supply and the capacity value that maximizes the service life of the energy storage flexible switch.

[0060] By assessing the risk of landslide damage on the mountain, the installation location of the energy storage flexible switch is determined, the annual cycle life and life cost of the battery are calculated, the usage method is determined, and finally the distributed power supply is combined to control the output to minimize the operation cost, thereby improving the power supply recovery efficiency and power supply quality.

[0061] In the present application, the risk of landslide damage is firstly obtained and the installation position of the energy storage type flexible switch is determined. The evaluation process is not limited. In one embodiment, S1 includes:

[0062] Based on the regression method, the monotonic function m representing the hazard intensity of each substation area is obtained from the historical data of landslides in the distribution substation area. i , the landslide historical data include geographical location, soil type, and geological characteristics;

[0063] Determine the corresponding hazard weight ω according to the economic loss of the power distribution area after the disaster i , calculate and obtain the landslide damage risk index S l for:

[0064]

[0065] where i l is the number of stations, n l is the total number of areas;

[0066] For S l Normalize it and take its value in the interval [0,1], S l The larger the size, the greater the damage caused by landslides;

[0067] Set when S l When it is greater than the set risk threshold, it indicates that the risk of landslide damage is high, and it is necessary to install the energy storage flexible switch to restore power supply after the disaster.

[0068] The present application includes but is not limited to using a regression method to obtain a monotonic function m representing the hazard intensity of each substation area. i In addition to the geographical location, soil type, and geological characteristics, the landslide historical data may also include other characteristics. Those skilled in the art can reasonably select different types of characteristic data based on the influence of calculation accuracy and weight, and the possibility of landslides in different regions may change due to rainfall, earthquakes, etc. For example, for the same soil type mountain, some areas have less rainfall, and some areas have more rainfall, such as the south. According to historical data, the weight of the soil type feature in different regions is different. In addition, in some areas, the temperature difference between day and night is poor, and thermal expansion and contraction are severe, which may easily lead to landslides, or other factors, etc., which are not limited in this application.

[0069] It should be pointed out that in the selection of features and weights that affect landslides in this application, it can be known that in accordance with the preset parameters and types, it can also be limited in a dynamic way, such as pre-entering the address structure of the region, and then combining future meteorological conditions, such as temperature, wind, rainfall, etc., to achieve dynamic adjustment of the weights of different features, or after an equipment failure occurs, adjust its parameters according to the maintenance and difficulty of the equipment, so that the difference between it and the actual situation becomes smaller. For example, after a landslide occurs, the power grayscale is carried out, and it is found that the difficulty is much greater than expected, and the power quality is difficult to meet expectations after the power is restored. Therefore, the possibility of landslides in the area can be appropriately increased, thereby changing the power restoration strategy. Or, due to the upgrading of the power equipment itself, the recovery capacity is improved, and the ability to resist disasters such as landslides is improved. The threshold can be appropriately increased, or the threshold can be lowered due to equipment aging and other reasons.

[0070] Specifically, the S1 includes:

[0071] According to the historical landslide disaster data and geological information of the distribution area, the probability of landslide under different slopes and soil conditions is calculated, and the hazard intensity monotonic function is fitted based on the regression method. The landslide damage risk index is obtained based on the post-disaster cost loss and the installation location of the energy storage soft switch is determined.

[0072] In order to realize the above-mentioned dynamic optimization configuration and achieve the best power supply effect, in one embodiment, S1 also includes:

[0073] The risk threshold is set.

[0074] It should be noted that the risk threshold can be set manually or automatically by the system. Manual adjustment means that the staff inputs the risk threshold through a control panel or remote input, while automatic adjustment means that the entire control system automatically evaluates the equipment based on the number of maintenance times, service life, etc., and generates a risk threshold. This application does not limit the setting method of the risk threshold.

[0075] In this application, it is necessary to achieve the lowest cost by calculating the energy storage capacity, effect, service life, etc. of the energy storage type flexible switch, and there is no limitation on the specific parameter calculation.

[0076] The voltage source converter in the energy storage flexible switch in the present application can flexibly transmit active power flow and adjust reactive power. After the power supply stations in some areas are damaged due to landslides, distributed power sources in other areas can be called upon to restore power supply to the affected areas.

[0077] The energy storage link smoothes power fluctuations by storing and releasing electric energy, reducing the uncertainty of load demand. When the distributed power sources in other areas are new energy sources with large output fluctuations, the energy storage link can adjust their fluctuations to ensure the quality of power supply restoration.

[0078] Traditional soft switches with energy storage only meet the power balance equation, energy storage charge state constraints, charge and discharge power constraints, etc., which may cause excessive discharge of the battery, reduce the battery life, and increase the investment cost of the structure.

[0079] Therefore, the above-mentioned problem needs to be solved in the present application to reduce the use cost. In one embodiment, the S2 includes:

[0080] The energy storage type flexible switch control model is established by calculating and based on the charge and discharge cycle process of the energy storage type flexible switch, the discharge depth at the moment before charging, the battery cycle life, and the equivalent full cycle number at 100% discharge depth converted from each discharge cycle of different depths according to the energy storage life:

[0081] According to the energy storage type flexible switch control model, the annual cycle life of the battery T is calculated. i,cyc and life cycle cost C i,ES .

[0082] Wherein, the S2 includes:

[0083] The charge-discharge cycle process is a charge-discharge cycle that occurs when the energy storage type flexible switch changes from a discharge process to a charging process:

[0084]

[0085] in is a 0-1 variable. When the energy storage state is from charging to discharging, In other cases

[0086] The discharge depth at the moment before charging is the discharge depth at the moment before charging. Represents the battery cycle discharge depth

[0087]

[0088]

[0089] Calculate the battery cycle life include:

[0090]

[0091] Where N0 is the number of cycles when the battery reaches the end of its life at 100% discharge depth, k p is the curve fitting parameter, with a value between 1.1 and 2.1;

[0092] The equivalent full cycle number is calculated by converting the energy storage life into the equivalent full cycle number at 100% discharge depth at each discharge cycle of different depths, where the daily equivalent full cycle number is N i,eq :

[0093]

[0094] Where S is the number of clustered scenes;

[0095] Calculate the annual cycle life of the battery T i,cyc and life cycle cost C i,ES for

[0096] T i,cyc =N0 / (365·N i,eq ) (7),

[0097]

[0098] Among them, C i,inv,ES is the battery investment cost without considering the battery life, and r is the discount rate.

[0099] This model can change the charging and discharging strategy of energy storage soft switches, reduce unnecessary charging and discharging depth, increase component service life on the basis of restoring power supply, and thus reduce costs.

[0100] It should be pointed out that the above embodiment is only one way of calculation, and other modes may also be used for calculation, which is not limited in this application.

[0101] After completing the use strategy for the energy storage type flexible switch, the present application needs to control the energy storage type flexible switch, the distributed power source and the Xining to achieve power supply recovery. The specific calculation process and control method are not limited. In one embodiment, the S3 includes:

[0102] S31, through convex relaxation or large M method, linearization of objective function and constraint condition calculation and control, ensure that the power output and energy storage type flexible switch configuration range can make the model have a feasible solution;

[0103] S32, controlling the distributed power source and the energy storage soft switch to restore power supply to the disaster-stricken area, and obtaining the minimum distributed power source output and energy storage soft switch capacity investment that can meet fault recovery by minimizing the commissioning cost of the fault recovery equipment.

[0104] The distribution network fault recovery method described in step S3 that considers the adjustment effects of energy storage flexible switches and distributed power sources on the distribution network at the same time:

[0105] The core of the algorithm in this application is:

[0106] In the first stage, the historical landslide disaster data and geological information of the distribution station area were used to find the probability of landslides under different slopes and soil conditions, and a monotonic function of the hazard intensity was fitted based on the regression method.

[0107] Then, combined with the post-disaster cost loss, the landslide damage risk index is obtained and the installation location of the energy storage soft switch is determined.

[0108] The second stage controls the distributed power supply and energy storage soft switch to restore power supply to the affected areas. By minimizing the commissioning cost of the fault recovery equipment, the minimum distributed power supply output and energy storage soft switch capacity investment that can meet the fault recovery are obtained, aiming to minimize the commissioning cost of the power supply equipment that meets the post-disaster power supply needs.

[0109] Specifically, in one embodiment, the S32 includes:

[0110] Based on the condition that the operation cost of power supply equipment that meets the post-disaster power supply demand is the minimum, the objective function is calculated as:

[0111]

[0112]

[0113] where c DG , c p , c DC are the unit power investment costs of distributed power supply, converter and DC-DC converter respectively; r is the discount rate; P DG,t P is the active power output of distributed power source; L,t Power loss for operation; is the line loss power; They are the power losses of two converters of energy storage soft switch; is the power loss of the DC-DC converter; x i ,x j ,y i are the planned capacities of VSC and DC-DC at nodes i and j of intelligent energy storage soft switches respectively; Ω l ,Ω SOP-ES ,Ω ESThey are respectively the line, the energy storage soft switch, and the battery node set, which need to satisfy the power balance equation, the upper and lower limits of the energy storage charge state, the energy storage charging and discharging constraints, the battery power timing equation, the battery scheduling cycle charge state equation, the power flow equation, the distributed power supply power constraints and the power grid operation safety constraints.

[0114] In one embodiment of the present application, a distribution network fault recovery method based on an energy storage flexible switch includes the following four steps:

[0115] 1) According to the historical data of landslide disasters in the distribution station area, a monotonic function of the hazard intensity was fitted based on the regression method, and the weight of each area was obtained based on the post-disaster economic losses.

[0116] 2) Calculate the landslide damage risk index (1) and obtain the installation position of the energy storage flexible switch through the threshold.

[0117] 3) Control the output of distributed generation and the capacity of energy storage flexible switch to restore power supply to the faulty area. Linearize the objective function and constraints through convex relaxation or large M method, and use Matlab to calculate (9) to ensure that the configuration range of power output and energy storage flexible switch can make the model have a feasible solution.

[0118] 4) With the goal of minimizing the commissioning cost, the cplex commercial solver is used to optimize the distributed power output value and the capacity value that maximizes the service life of the energy storage flexible switch.

[0119] To summarize, the distribution network fault recovery method based on the energy storage type flexible switch provided in the embodiment of the present invention determines the installation location of the energy storage type flexible switch by assessing the risk of landslide damage, calculates the annual cycle life and life cost of the battery, determines the usage method, and finally combines the distributed power source to minimize the operation cost to control the output, thereby improving the power supply recovery efficiency and power supply quality, and improving the fault recovery efficiency and power supply quality of the distribution network.

[0120] The above is a detailed introduction to the distribution network fault recovery method based on energy storage flexible switches provided by the present invention. This article uses specific examples to illustrate the principles and implementation methods of the present invention. The description of the above embodiments is only used to help understand the method of the present invention and its core idea. It should be pointed out that for ordinary technicians in this technical field, without departing from the principles of the present invention, several improvements and modifications can be made to the present invention, and these improvements and modifications also fall within the scope of protection of the claims of the present invention.

Claims

1. A distribution network fault recovery method based on energy storage flexible switch, characterized in that: include: S1, based on the historical data of landslide disasters in the distribution area, assess the landslide damage risk and determine the installation location of the energy storage flexible switch; S2, calculating and determining the control strategy of the energy storage type flexible switch based on the annual cycle life and life cost of the battery of the energy storage type flexible switch, smoothing power fluctuations and reducing load demand uncertainty by storing and releasing electric energy; S3, with the goal of minimizing the commissioning cost, calculates and outputs the power output value of the distributed power source and the capacity value that maximizes the service life of the energy storage type flexible switch; The S1 includes: Based on the regression method, the monotonic function m representing the hazard intensity of each substation area is obtained from the historical data of landslides in the distribution substation area. i , the landslide historical data include geographical location, soil type, and geological characteristics; Determine the corresponding hazard weight ω according to the economic loss of the power distribution area after the disaster i , calculate and obtain the landslide damage risk index S l for: where i l is the number of stations, n l is the total number of areas; For S l Normalize it and take its value in the interval [0,1], S l The larger the size, the greater the damage caused by landslides; Set when S l When it is greater than the set risk threshold, it indicates that the risk of landslide damage is high, and it is necessary to install the energy storage type flexible switch to restore power supply after the disaster; The S1 includes: According to the historical landslide disaster data and geological information of the distribution area, the probability of landslide under different slopes and different soil conditions is calculated, and the hazard intensity monotonic function is fitted based on the regression method, and the landslide damage risk index is obtained according to the post-disaster cost loss and the installation position of the energy storage soft switch is determined; The S1 also includes: setting the risk threshold; The S2 includes: The energy storage type flexible switch control model is established by calculating and based on the charge and discharge cycle process of the energy storage type flexible switch, the discharge depth at the moment before charging, the battery cycle life, and the equivalent full cycle number at 100% discharge depth converted from each discharge cycle of different depths according to the energy storage life: According to the energy storage type flexible switch control model, the annual cycle life of the battery T is calculated. i,cyc and life cycle cost C i,ES ; The S2 includes: The charge-discharge cycle process is a charge-discharge cycle that occurs when the energy storage type flexible switch changes from a discharge process to a charging process: in is a 0-1 variable. When the energy storage state is from charging to discharging, In other cases The discharge depth at the moment before charging is the discharge depth at the moment before charging. Represents the battery cycle discharge depth Calculate the battery cycle life include: Where N0 is the number of cycles when the battery reaches the end of its life at 100% discharge depth, k p is the curve fitting parameter, with a value between 1.1 and 2.1; The equivalent full cycle number is calculated by converting the energy storage life into the equivalent full cycle number at 100% discharge depth at each discharge cycle of different depths, where the daily equivalent full cycle number is N i,eq : Where S is the number of clustered scenes; Calculate the annual cycle life of the battery T i,cyc and life cycle cost C i,ES for T i,cyc =N0 / (365·N i,eq ) (7), Among them, C i,inv,ES is the battery investment cost without considering the battery life, and r is the discount rate.

2. The distribution network fault recovery method based on energy storage type flexible switch according to claim 1, characterized in that: The S3 includes: S31, through convex relaxation or large M method, linearization of objective function and constraint condition calculation and control is performed to ensure that the power output and energy storage type flexible switch configuration range can make the model have a feasible solution; S32, controlling the distributed power source and the energy storage soft switch to restore power supply to the disaster-stricken area, and obtaining the minimum distributed power source output and energy storage soft switch capacity investment that can meet fault recovery by minimizing the commissioning cost of the fault recovery equipment.

3. The distribution network fault recovery method based on energy storage type flexible switch according to claim 2 is characterized in that: The S32 includes: Based on the condition that the operation cost of power supply equipment that meets the post-disaster power supply demand is the minimum, the objective function is calculated as: where c DG , c p , c DC are the unit power investment costs of distributed power supply, converter and DC-DC converter respectively; r is the discount rate; P DG,t P is the active power output of distributed power source; L,t For operating power loss; is the line loss power; They are the power losses of two converters of energy storage soft switch; is the power loss of the DC-DC converter; x i ,x j ,y i are the planned capacities of VSC and DC-DC at nodes i and j of intelligent energy storage soft switches respectively; Ω l ,Ω SOP-ES ,Ω ES They are respectively the line, the energy storage soft switch, and the battery node set, which need to satisfy the power balance equation, the upper and lower limits of the energy storage charge state, the energy storage charging and discharging constraints, the battery power timing equation, the battery scheduling cycle charge state equation, the power flow equation, the distributed power supply power constraints and the power grid operation safety constraints.

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