1. A fault self-healing evaluation method of an urban integrated energy system is characterized by providing the following novel fault self-healing evaluation indexes:

(1) self-healing recovery rate

After the power distribution network fails, the power supply recovery process is continued from the occurrence of the failure until the failure is completely cleared and normal power supply of the whole network is recovered, so that in the time period, the recovery of the load takes the total electric quantity of the load recovery into consideration on the premise of considering the importance level of the load instead of the instantaneous power recovery value under the failure section; therefore, a self-healing recovery rate index SHRR is proposed around the recovery electric quantity and the load level in the whole self-healing process, and is defined as H_SHRR：

In the formula: p_I,t、P_II,t、P_III,t，ω₁、ω₂、ω₃Respectively are I-level, II-level and III-level load actual recovery power and corresponding load level weight coefficients;the original power requirements of loads of I level, II level and III level at t moment; tc is the fault duration;

the self-healing recovery rate describes that after a fault occurs, the load recovery electric quantity with the weight recovered through self-healing control accounts for the proportion of the original power loss electric quantity; the self-healing recovery rate reflects the electric quantity supporting condition of the load within the fault duration; the higher the self-healing recovery rate is, the more guaranteed the power supply to the load, especially the power supply to the important load is;

(2) self-healing recovery rate

In order to shorten the power failure time of a user side and reduce the load power failure loss, the intelligent power distribution network requires that a fault-free power failure section is timely restored after the fault occurs; defining self-healing recovery speed SHRS according to the speed of power supply recovery of a fault-free section affected by a fault; the fault duration mainly comprises 4 parts, namely fault section positioning time T1, fault isolation and non-fault section recovery time T2, fault section emergency repair time T3 and full-network recovery operation time T4;

after the fault location T1 and the fault isolation and non-fault section recovery time T2, the load self-healing operation of the non-fault section is completed, and all the recoverable loads have been completely recovered, so the self-healing recovery speed SHRS is defined as the sum of the fault section location time T1 and the fault isolation and non-fault section recovery time T2, and is defined as H_SHRS：

H_SHRS＝T₁+T₂

The self-healing recovery speed can reflect the response speed of the system to the fault and visually reflect the recovery time of the load of the non-fault section;

(3) self-healing control operation complexity

The self-healing control operation complexity SHCC is characterized by the frequency degree of the switch operation; frequent switching operation increases the complexity of the self-healing recovery process, so the times of the switching operation in the self-healing process are counted and used as a self-healing index to measure the complexity or the cost of the self-healing operation, when the self-healing process is off-network, the load and the DG in the island black start process need to be sequentially accessed into the island, the complexity of the self-healing control operation is also increased in the process, and the self-healing control operation complexity SHCC is defined as H_SHCC：

Wherein the content of the first and second substances,

in the formula:the action times of the line switch in the fault recovery process are obtained; s is a distribution network switch set; tc is the fault duration;the state of the switch s at the time t is that the switch is closed and is set to be 1, and the switch is opened and is set to be 0;andrespectively representing the operation times of the load and the DG in the fault recovery process;

(4) self-healing sustainable time coverage

The self-healing sustainable time coverage SHCT is used for describing the sustainable power supply capability of the intelligent power distribution network after power supply recovery is realized in a non-fault area affected by a fault through a self-healing control strategy after the fault isolation is carried out on the intelligent power distribution network;

the self-healing can be divided into 2 modes of grid connection and grid disconnection, and the grid connection self-healing mode is assumed to have enough load supporting capacity, but the self-healing mode based on island operation needs to consider the sustainable operation capacity of energy storage or distributed power generation; an intelligent microgrid is integrated in an intelligent power distribution network, the intelligent microgrid can operate in 2 modes of grid connection and off-grid, and when the intelligent microgrid operates off-grid, the problem of sustainable time also exists; the duration of the fault process is the sum of the time T1, the time T2, the time T3 and the time T4, and the maximum power supply time which can be increased by self-healing control measures before the power supply of the island or the intelligent microgrid is restored is the sum of the time T3 and the time T4;

the diesel generator, the fuel cell and the micro gas turbine with controllable output power can be preferentially considered as balance nodes when the off-grid self-healing operation is carried out; the time sequence characteristic is determined by the load and DG output by adopting a PQ (U) control strategy; when a diesel generator, a fuel cell and a micro gas turbine are used as balance nodes, the self-healing sustainable time T^susIs represented as follows:

T^sus＝min(T^P,T₃+T₄)

in the formula: t is^PThe maximum power support time of an island is obtained;the active demand of a load node in an island at the time t is met;available capacities of DG and stored energy at the moment t are respectively; when the load demand is smaller than the maximum power output of the power supply in the island, the island can be considered to be in continuous operation; when the energy storage system is used as a balance node of an island, the maximum power support time of the island is met, and the SOC of the energy storage state of charge is ensured to be within a preset range;

the power supply is recovered based on the spare interconnection line, as long as the power supply is continuously supplied within the capacity range of the transformer and the line, so that the coverage rate of the self-healing sustainable time in a grid-connected self-healing mode is assumed to be 100% when the power is recovered through the interconnection line; after the intelligent power distribution network fails, a plurality of island areas can be formed, and different island power supporting conditions are different, so that different self-healing sustainable time exists; defining the ratio of the average power of each island to the average power of all recovered loads as the self-healing sustainable time coverage rate weight lambda of the island, and defining the self-healing sustainable time coverage rate SHCT of the system as H_SHCT：

In the formula:E_i、respectively setting the self-healing sustainable time, the electric quantity recovered in the self-healing sustainable time and the average power in the time of the ith island; lambda [ alpha ]_iSelf-healing sustainable time coverage rate weight corresponding to the island i; n is a radical of_soleIs a complete island set;

the longer the island supportable time is, the higher the self-healing sustainable time coverage rate is, and when the value is 100%, it means that the recovery scheme supportable time covers T3 and T4 until the faulty equipment is repaired.

2. The method for assessing fault self-healing of the urban integrated energy system according to claim 1, wherein a self-healing capability assessment method is further provided based on a novel fault self-healing assessment index, and specifically comprises the following steps:

1) inputting parameters including a network topological structure, the fault probability of each section, a load curve of each node and a DG output curve in an evaluation area;

2) based on per power supply section failure probability beta_iCalculating weight r of self-healing capability level of each power supply section_iAnd I is the number of power supply sections:

3) performing expected fault simulation on each power supply section, simulating and analyzing the self-healing process of the section i after the fault occurs at the moment t, and calculating the self-healing capacity index of each section at the moment t after the fault occurs;

4) and (3) calculating the self-healing capability index of the whole system at the time t as follows:

5) making t equal to t +1, and re-executing the steps 3) and 4) until t equal to 24;

6) and (4) based on the self-healing capacity evaluation index values of the system at 24 moments, carrying out daily overall self-healing capacity evaluation calculation on the system.

Background

The connectivity problem of the power system network is closely related to electric energy production, electric energy transmission and electric energy consumption, the robustness of a network structure is reflected, the larger the connectivity of the power network is, the stronger the damage resistance is, and the higher the self-healing capability of the power grid is. Therefore, the connectivity of the power grid is an important index for evaluating the self-healing degree of the power grid.

The higher the connectivity of the network is, the more flexibly the network can change the operation mode when a fault occurs to realize fault self-healing. If the network after the fault is connected, the self-healing path exists in the network. Therefore, the method can be used for a starting item of a fault self-healing strategy, namely, after a fault occurs and a fault element is isolated, whether a self-healing path exists in the network is quickly judged, if the self-healing path does not exist, the network cannot realize self-healing, and power supply to a power loss area is realized by adopting a manual scheduling or manual maintenance and fault removal mode of a dispatcher; if the self-healing path exists, the self-healing strategy can be started to select the optimal scheme for power restoration.

Traditional index

(1) Index of self-healing speed

The extent to which power quality fluctuations of the power grid (including power interruptions and voltage dips) affect different consumers varies. According to the severity of the influence of power supply quality fluctuation on the electric equipment, the power load is divided into the following three types:

1) a normal load. I.e. an electrical load that is substantially unaffected by fluctuations in the quality of the power supply or that causes less losses. Such as general lighting equipment and household appliances, electric heaters, ventilators, etc.

2) A sensitive load. The power load is a power load which is influenced and damaged by power supply quality fluctuation of several cycles, such as a programmable controller, a variable frequency speed regulation device and the like.

3) A severe load. The load is a load which has strict requirements on the quality of power supply energy and can be affected and damaged by the fluctuation of more than one cycle, such as an integrated circuit chip manufacturing assembly line, a computer system in a bank and a security center and the like.

Therefore, the self-healing capacity of the intelligent distribution network is described quantitatively according to the self-healing speed and serves as a quantitative index for evaluating the self-healing capacity of the intelligent distribution network. The influence on the user and the required release control technology are comprehensively considered, and the self-healing speed can be divided into four stages:

1) first-level self-healing speed. The self-healing time is within one cycle (the power grid is milliseconds), and the self-healing time has the effect of making a user feel no, so that the self-healing time can be called as seamless self-healing.

2) Second-level self-healing speed. The self-healing is also called cycle-level self-healing, refers to the self-healing recovery of the power supply quality within the fluctuation time of more than one cycle and dozens of milliseconds, and basically has no influence on common loads and common sensitive loads.

3) And (3) three-level self-healing speed. The self-healing recovery of the power supply quality fluctuation time within a few seconds has certain influence on sensitive loads but has no influence on common loads.

4) Four-level self-healing speed. The method is also called minute-level self-healing, which means that the self-healing recovery is carried out within 3 minutes after the fluctuation time of the power supply quality, and although users feel that power failure occurs, the recovery is carried out within a short time, the normal operation of sensitive loads is influenced, but the normal operation of the sensitive loads is basically not influenced.

And if the power failure time exceeds 3 minutes, the self-healing is not considered, and the power failure is counted in the power supply reliability index. Therefore, the self-healing speed index describes the self-healing recovery capability of the intelligent power distribution network to short-time power failure within 3 minutes. Certainly, the selection of the self-healing speed is a technical and economic problem, and the faster the self-healing speed is, the greater the investment of power grid equipment is, so that a proper self-healing speed needs to be selected from meeting the load requirement of a user for a specific power distribution network. The self-healing speed index is also used as an index for evaluating the self-healing capacity of a certain feeder line of the intelligent distribution network or a certain cell network.

(2) Index of self-healing rate of power supply

The index of the power supply self-healing rate is used for describing the self-healing recovery capability of the power distribution network of one region or even one city to accident potential and power supply faults. In actual engineering, it is difficult to accurately monitor and count the hidden trouble, and for convenience of application, the power supply self-healing rate index is defined as an index describing the fault self-healing recovery capability. The first power supply self-healing index is power supply fault self-healing, which is defined as a percentage value of the total number of users that have recovered from the fault self-healing to the total number of users affected by the fault within a statistical period (e.g., one year), that is:

in the formula, the number of users affected by each fault refers to the number of users connected with the line within the fault influence range; the number of households per fault self-healing refers to the number of households which recover power supply after the power distribution network self-healing operation is not affected by the fault or short power failure, and is the difference between the number of users connected within the fault influence range and the number of households actually suffering power failure. Faults are counted through the number of times of faults recorded by a substation protection and fault recording device, and the number of the influenced users is counted according to the number of users connected with the influenced lines through a network operation structure during fault; and the actual number of the power failure users can be counted through the power distribution terminal and the smart meter.

The average self-healing times of the users is another power supply self-healing rate index, which is the average times of the self-healing success of each user after suffering from a fault within a statistical period, namely:

the reliability rate of power supply is closely related to the self-healing of power supply. The power supply fault self-healing index describes the self-healing capacity of the power distribution network in the aspect of reducing fault and power failure, and the power distribution network with strong self-healing capacity is high in power supply reliability. In fact, the self-healing speed is also a key index of the self-healing effect of power supply, and the self-healing speed is directly related to the influence degree on sensitive users. Strictly speaking, these factors should be considered as the power supply self-healing rate index for evaluating the self-healing capability of the whole power distribution network, and the further research and improvement is needed.

In conclusion, the traditional indexes do not consider the time sequence and the volatility of load and distributed power generation, and do not relate to the complexity of control operation and the sustainable supporting capability after recovery. Therefore, more effective and comprehensive evaluation indexes are required.

Disclosure of Invention

The invention aims to provide a fault self-healing evaluation method for an urban comprehensive energy system, which can make risk evaluation and self-healing reaction in advance and ensure the power supply of important loads.

In order to achieve the purpose, the technical scheme of the invention is as follows: a fault self-healing evaluation method for an urban comprehensive energy system provides the following novel fault self-healing evaluation indexes:

(1) self-healing recovery rate

After the power distribution network fails, the power supply recovery process is continued from the occurrence of the failure until the failure is completely cleared and normal power supply of the whole network is recovered, so that in the time period, the recovery of the load takes the total electric quantity of the load recovery into consideration on the premise of considering the importance level of the load instead of the instantaneous power recovery value under the failure section; therefore, a self-healing recovery rate index SHRR is proposed around the recovery electric quantity and the load level in the whole self-healing process, and is defined as H_SHRR：

In the formula: p_I,t、P_II,t、P_III,t，ω₁、ω₂、ω₃Respectively are I-level, II-level and III-level load actual recovery power and corresponding load level weight coefficients;the original power requirements of loads of I level, II level and III level at t moment; tc is the fault duration;

the self-healing recovery rate describes that after a fault occurs, the load recovery electric quantity with the weight recovered through self-healing control accounts for the proportion of the original power loss electric quantity; the self-healing recovery rate reflects the electric quantity supporting condition of the load within the fault duration; the higher the self-healing recovery rate is, the more guaranteed the power supply to the load, especially the power supply to the important load is;

(2) self-healing recovery rate

In order to shorten the power failure time of a user side and reduce the load power failure loss, the intelligent power distribution network requires that a fault-free power failure section is timely restored after the fault occurs; defining self-healing recovery speed SHRS according to the speed of power supply recovery of a fault-free section affected by a fault; the fault duration mainly comprises 4 parts, namely fault section positioning time T1, fault isolation and non-fault section recovery time T2, fault section emergency repair time T3 and full-network recovery operation time T4;

after the fault location T1 and the fault isolation and non-fault section recovery time T2, the load self-healing operation of the non-fault section is completed, and all the recoverable loads have been completely recovered, so the self-healing recovery speed SHRS is defined as the sum of the fault section location time T1 and the fault isolation and non-fault section recovery time T2, and is defined as H_SHRS：

H_SHRS＝T₁+T₂

The self-healing recovery speed can reflect the response speed of the system to the fault and visually reflect the recovery time of the load of the non-fault section;

(3) self-healing control operation complexity

Self-healing control operation complexity SHCC pass-pair switchThe frequency of operation; frequent switching operation increases the complexity of the self-healing recovery process, so the times of the switching operation in the self-healing process are counted and used as a self-healing index to measure the complexity or the cost of the self-healing operation, when the self-healing process is off-network, the load and the DG in the island black start process need to be sequentially accessed into the island, the complexity of the self-healing control operation is also increased in the process, and the self-healing control operation complexity SHCC is defined as H_SHCC：

Wherein the content of the first and second substances,

in the formula:the action times of the line switch in the fault recovery process are obtained; s is a distribution network switch set; tc is the fault duration;the state of the switch s at the time t is that the switch is closed and is set to be 1, and the switch is opened and is set to be 0;andrespectively representing the operation times of the load and the DG in the fault recovery process;

(4) self-healing sustainable time coverage

The self-healing sustainable time coverage SHCT is used for describing the sustainable power supply capability of the intelligent power distribution network after power supply recovery is realized in a non-fault area affected by a fault through a self-healing control strategy after the fault isolation is carried out on the intelligent power distribution network;

the self-healing can be divided into 2 modes of grid connection and grid disconnection, and the grid connection self-healing mode is assumed to have enough load supporting capacity, but the self-healing mode based on island operation needs to consider the sustainable operation capacity of energy storage or distributed power generation; an intelligent microgrid is integrated in an intelligent power distribution network, the intelligent microgrid can operate in 2 modes of grid connection and off-grid, and when the intelligent microgrid operates off-grid, the problem of sustainable time also exists; the duration of the fault process is the sum of the time T1, the time T2, the time T3 and the time T4, and the maximum power supply time which can be increased by self-healing control measures before the power supply of the island or the intelligent microgrid is restored is the sum of the time T3 and the time T4;

the diesel generator, the fuel cell and the micro gas turbine with controllable output power can be preferentially considered as balance nodes when the off-grid self-healing operation is carried out; the time sequence characteristic is determined by the load and DG output by adopting a PQ (U) control strategy; when a diesel generator, a fuel cell and a micro gas turbine are used as balance nodes, the self-healing sustainable time T^susIs represented as follows:

T^sus＝min(T^P,T₃+T₄)

in the formula: t is^PThe maximum power support time of an island is obtained;the active demand of a load node in an island at the time t is met;available capacities of DG and stored energy at the moment t are respectively; when the load demand is smaller than the maximum power output of the power supply in the island, the island can be considered to be in continuous operation; when the energy storage system is used as a balance node of an island, the maximum power support time of the island is met, and the SOC of the energy storage state of charge is ensured to be within a preset range;

the recovery power supply based on the spare interconnection line can continuously supply power within the range of the transformer and the line capacity, so that the self-recovery mode under the grid-connected self-recovery mode is assumed when the recovery is carried out through the interconnection lineThe sustainable time coverage rate is 100%; after the intelligent power distribution network fails, a plurality of island areas can be formed, and different island power supporting conditions are different, so that different self-healing sustainable time exists; defining the ratio of the average power of each island to the average power of all recovered loads as the self-healing sustainable time coverage rate weight lambda of the island, and defining the self-healing sustainable time coverage rate SHCT of the system as H_SHCT：

In the formula:E_i、respectively setting the self-healing sustainable time, the electric quantity recovered in the self-healing sustainable time and the average power in the time of the ith island; lambda [ alpha ]_iSelf-healing sustainable time coverage rate weight corresponding to the island i; n is a radical of_soleIs a complete island set;

the longer the island supportable time is, the higher the self-healing sustainable time coverage rate is, and when the value is 100%, it means that the recovery scheme supportable time covers T3 and T4 until the faulty equipment is repaired.

In an embodiment of the present invention, based on the novel fault self-healing evaluation index, a self-healing capability evaluation method is further provided, which specifically includes:

1) inputting parameters including a network topological structure, the fault probability of each section, a load curve of each node and a DG output curve in an evaluation area;

2) based on per power supply section failure probability beta_iCalculating weight r of self-healing capability level of each power supply section_iAnd I is the number of power supply sections:

3) performing expected fault simulation on each power supply section, simulating and analyzing the self-healing process of the section i after the fault occurs at the moment t, and calculating the self-healing capacity index of each section at the moment t after the fault occurs;

4) and (3) calculating the self-healing capability index of the whole system at the time t as follows:

5) making t equal to t +1, and re-executing the steps 3) and 4) until t equal to 24;

6) and (4) based on the self-healing capacity evaluation index values of the system at 24 moments, carrying out daily overall self-healing capacity evaluation calculation on the system.

Compared with the prior art, the invention has the following beneficial effects: the method can make risk assessment and self-healing reaction in advance, and the power supply of important loads is guaranteed.

Drawings

Fig. 1 is a schematic diagram of a self-healing capability evaluation process according to the present invention.

Fig. 2 is a schematic diagram of a fault recovery process.

Detailed Description

The technical scheme of the invention is specifically explained below with reference to the accompanying drawings.

The invention provides a fault self-healing evaluation method of an urban comprehensive energy system, which provides the following novel fault self-healing evaluation indexes:

(1) self-healing recovery rate

After the power distribution network fails, the power supply recovery process is continued from the occurrence of the failure until the failure is completely cleared and normal power supply of the whole network is recovered, so that in the time period, the recovery of the load takes the total electric quantity of the load recovery into consideration on the premise of considering the importance level of the load instead of the instantaneous power recovery value under the failure section; therefore, a self-healing recovery rate index (SHRR) is proposed around the recovery power and load level in the whole self-healing process, and defined as H_SHRR：

In the formula: p_I,t、P_II,t、P_III,t，ω₁、ω₂、ω₃Respectively are I-level, II-level and III-level load actual recovery power and corresponding load level weight coefficients;the original power requirements of loads of I level, II level and III level at t moment; tc is the fault duration;

the self-healing recovery rate describes that after a fault occurs, the load recovery electric quantity with the weight recovered through self-healing control accounts for the proportion of the original power loss electric quantity; the self-healing recovery rate reflects the electric quantity supporting condition of the load within the fault duration; the higher the self-healing recovery rate is, the more guaranteed the power supply to the load, especially the power supply to the important load is;

(2) self-healing recovery rate

In order to shorten the power failure time of a user side and reduce the load power failure loss, the intelligent power distribution network requires that a fault-free power failure section is timely restored after the fault occurs; defining self-healing recovery speed (SHRS) according to the speed of power supply recovery of a fault-free section affected by a fault; the fault duration mainly consists of 4 parts, as shown in fig. 2, namely fault section positioning time T1, fault isolation and non-fault section recovery time T2, fault section emergency repair time T3 and full-network recovery operation time T4;

after the fault location T1 and the fault isolation and non-fault section recovery time T2, the load self-healing operation of the non-fault section is completed, and all the recoverable loads have been completely recovered, so the self-healing recovery speed SHRS is defined as the sum of the fault section location time T1 and the fault isolation and non-fault section recovery time T2, and is defined as H_SHRS：

H_SHRS＝T₁+T₂

The self-healing recovery speed is obviously influenced by factors such as the distribution network automation level, and the like, the index can reflect the response speed of the system to the fault and visually reflect the recovery time of the load of the non-fault section.

(3) Self-healing control operation complexity

Self-healing control operation complexity (SHCC) is characterized by how often switching operations are performed; frequent switching operation increases the complexity of the self-healing recovery process, so the times of the switching operation in the self-healing process are counted and used as a self-healing index to measure the complexity or the cost of the self-healing operation, when the self-healing process is off-network, the load and the DG in the island black start process need to be sequentially accessed into the island, the complexity of the self-healing control operation is also increased in the process, and the self-healing control operation complexity SHCC is defined as H_SHCC：

Wherein the content of the first and second substances,

in the formula:the action times of the line switch in the fault recovery process are obtained; s is a distribution network switch set; tc is the fault duration;the state of the switch s at the time t is that the switch is closed and is set to be 1, and the switch is opened and is set to be 0;andrespectively representing the operation times of the load and the DG in the fault recovery process;

(4) self-healing sustainable time coverage

Self-healing sustainable coverage time (SHCT) is used for describing sustainable power supply capability of a non-fault area affected by a fault after the fault isolation of the intelligent power distribution network is achieved through a self-healing control strategy;

the self-healing can be divided into 2 modes of grid connection and grid disconnection, and the grid connection self-healing mode is assumed to have enough load supporting capacity, but the self-healing mode based on island operation needs to consider the sustainable operation capacity of energy storage or distributed power generation; an intelligent microgrid is integrated in an intelligent power distribution network, the intelligent microgrid can operate in 2 modes of grid connection and off-grid, and when the intelligent microgrid operates off-grid, the problem of sustainable time also exists; the duration of the fault process is the sum of the time T1, the time T2, the time T3 and the time T4, and the maximum power supply time which can be increased by self-healing control measures before the power supply of the island or the intelligent microgrid is restored is the sum of the time T3 and the time T4;

for diesel generators, fuel cells, micro-generators with controllable output powerThe type gas turbine can be preferentially considered as a balance node when the off-network self-healing operation is carried out; the time sequence characteristic is determined by the load and DG output by adopting a PQ (U) control strategy; when a diesel generator, a fuel cell and a micro gas turbine are used as balance nodes, the self-healing sustainable time T^susIs represented as follows:

T^sus＝min(T^P,T₃+T₄)

in the formula: t is^PThe maximum power support time of an island is obtained;the active demand of a load node in an island at the time t is met;available capacities of DG and stored energy at the moment t are respectively; when the load demand is smaller than the maximum power output of the power supply in the island, the island can be considered to be in continuous operation; when the energy storage system is used as a balance node of an island, the maximum power supporting time of the island is required to be met, and the state of charge (SOC) of the energy storage is ensured to be in a preset range;

the power supply is recovered based on the spare interconnection line, as long as the power supply is continuously supplied within the capacity range of the transformer and the line, so that the coverage rate of the self-healing sustainable time in a grid-connected self-healing mode is assumed to be 100% when the power is recovered through the interconnection line; after the intelligent power distribution network fails, a plurality of island areas can be formed, and different island power supporting conditions are different, so that different self-healing sustainable time exists; defining the ratio of the average power of each island to the average power of all recovered loads as the self-healing sustainable time coverage rate weight lambda of the island, and defining the self-healing sustainable time coverage rate SHCT of the system as H_SHCT：

In the formula:E_i、respectively setting the self-healing sustainable time, the electric quantity recovered in the self-healing sustainable time and the average power in the time of the ith island; lambda [ alpha ]_iSelf-healing sustainable time coverage rate weight corresponding to the island i; n is a radical of_so_leIs a complete island set;

the longer the island supportable time is, the higher the self-healing sustainable time coverage rate is, and when the value is 100%, it means that the recovery scheme supportable time covers T3 and T4 until the faulty equipment is repaired.

The longer the island supportable time is, the higher the self-healing sustainable time coverage rate is, and when the value is 100%, the recovery scheme supportable time covers T3 and T4 until the fault equipment is repaired. Because DG and load have great randomness and volatility in the island, and capacity constraints such as energy storage, fuel cell, diesel generator also lead to the island to support the time limited, be difficult to guarantee the long-time safe operation of island, so need consider the sustainable time problem of self-healing. Therefore, the SHCT is used as a relevant index for self-healing capability evaluation of the intelligent power distribution network and has an important reference value.

As shown in fig. 1, based on the novel fault self-healing evaluation index, a self-healing capability evaluation method is also provided, and the specific flow is as follows:

1) inputting parameters including a network topological structure, the fault probability of each section, a load curve of each node and a DG output curve in an evaluation area;

2) based on per power supply section failure probability beta_iCalculating weight r of self-healing capability level of each power supply section_iAnd I is the number of power supply sections:

3) performing expected fault simulation on each power supply section, simulating and analyzing the self-healing process of the section i after the fault occurs at the moment t, and calculating the self-healing capacity index of each section at the moment t after the fault occurs;

4) and (3) calculating the self-healing capability index of the whole system at the time t as follows:

5) making t equal to t +1, and re-executing the steps 3) and 4) until t equal to 24;

6) and (4) based on the self-healing capacity evaluation index values of the system at 24 moments, carrying out daily overall self-healing capacity evaluation calculation on the system.

The above are preferred embodiments of the present invention, and all changes made according to the technical scheme of the present invention that produce functional effects do not exceed the scope of the technical scheme of the present invention belong to the protection scope of the present invention.