CN115693755A - Island division-based fault recovery method for power distribution network with distributed power supply - Google Patents
Island division-based fault recovery method for power distribution network with distributed power supply Download PDFInfo
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Abstract
The invention discloses a power distribution network fault recovery method containing a distributed power supply based on islanding, which comprises the following steps: s1: determining the classification of the DGs in the power distribution network; s2: establishing an island division model of a DG-containing power distribution network; s3: according to the minimum spanning tree principle, obtaining an island division method by applying an improved Kruskal algorithm; s4: establishing a fault recovery reconstruction model of the DG-containing power distribution network; s5: and (3) according to the grades of the loads in the power distribution network and the classification of the DGs, adopting an improved genetic algorithm to carry out optimization solution on the power distribution network reconstruction model, and obtaining the fault recovery method with the maximum important load power supply recovery amount and the minimum switching times. According to the method, by confirming the classification of DGs in the power distribution network, the power distribution network is subjected to island division by using an improved Kruskal algorithm, so that the fault can be quickly and effectively found; meanwhile, the power supply recovery of important loads and the action times of switching are considered, and an improved genetic algorithm is combined and applied, so that the power supply recovery capability of the power distribution network is enhanced, and the method has practical value for the fault recovery of the power distribution network.
Description
Technical Field
The invention relates to the field of power distribution network fault recovery, in particular to a power distribution network fault recovery method based on islanding and including distributed power supplies.
Background
In recent years, due to uncertainty of natural disasters and malicious attacks, the impact on the power grid is increasing, and for the power distribution network, due to the fault state of the main network, normal power supply of the power distribution network is difficult to recover quickly in the first time. Meanwhile, in order to meet the requirements of energy transformation and energy conservation and environmental protection, the large-scale access of a power grid into distributed renewable energy sources in China has become a necessary trend; DGs can utilize various scattered energy sources, the DGs (Distributed Generation, distributed power sources) can reduce loss generated in network operation, meanwhile, the utilization of the DGs for dividing islands has great significance in recovering important load power supply, fault isolation is facilitated, power failure loss is reduced, and the method is an important means for improving the elasticity of a power distribution network. At present, many researches on the island division and fault recovery strategy of a DG-containing power distribution network are conducted at home and abroad. In a scheme in the prior art, an island is preliminarily formed according to a power supply path of a DG in a distribution network, and a power supply recovery strategy based on island division considering demand side response is provided, but the condition of preferentially recovering important load power supply is not considered. Another scheme in the prior art finds a path for recovering power supply to an important load by using a deep search algorithm, and forms a fault recovery scheme based on islanding through model constraint evaluation, but the process of finding an optimal solution is slow. A rapid fault recovery strategy is provided based on islanding and considering priority recovery of important load power supply conditions, and effective recovery of a power distribution network is ensured.
Disclosure of Invention
The invention aims to solve the problem of fault recovery of a power distribution network containing a distributed power supply based on islanding, and the power distribution network is reconstructed by taking power supply recovery of maximized important loads and action times of minimized switches as objective functions and taking node voltage constraint, line current constraint and network topology constraint as constraint conditions after an improved Kruskal algorithm is applied to the power distribution network for islanding, so that power supply recovery of the power distribution network is realized, and the electric energy quality of the system is improved.
The invention provides a power distribution network reconstruction strategy containing distributed power sources based on island division, aiming at solving the problem of complexity of the distributed power sources in the power distribution network fault recovery process and improving the utilization rate and power supply reliability of the distributed power sources. According to the scheme, classification of DGs in the power distribution network is considered, an improved Kruskal algorithm is used for carrying out island division on the power distribution network, power restoration of important loads, action times of switching and the like are considered, a corresponding fault restoration scheme is formulated by using an improved genetic algorithm, power restoration capacity of the power distribution network can be greatly enhanced, and practical value is achieved for power distribution network fault restoration.
In order to solve the technical problem, the invention provides a power distribution network fault recovery method based on islanding and containing distributed power supplies, which comprises the following steps:
s1: determining the classification of DGs in the power distribution network;
s2: establishing an island division model containing a DG power distribution network according to an island division principle, the power balance of the power distribution network, the transmission line safety and an island radial structure;
s3: according to the minimum spanning tree principle, an island division method is obtained by applying an improved Kruskal algorithm;
s4: establishing a fault recovery reconstruction model of the power distribution network containing the DG according to the node voltage of the power distribution network, the current deviation and the isolated island radial structure;
s5: and (3) according to the grade of the load in the power distribution network and the classification of the DGs, carrying out optimization solution on the power distribution network reconstruction model after the island division by adopting an improved genetic algorithm to obtain the fault recovery method with the maximum important load power supply recovery amount and the minimum switching times.
Preferably, the specific step in step S3 is:
s31: accessing all DGs into a power grid, searching from top to bottom according to the bus numbers, and for buses which are not directly connected with DG nodes, accessing the DG nodes closest to the access points according to the DG weight to form an initial island;
s32: under the condition of meeting the power balance constraint, sequentially merging the first-level load, the second-level load and the third-level load which are divided according to the load grades into each island, checking the constraint condition once when one load is accessed, ensuring the maximization of the load, and sequentially traversing each island; s33: under the condition of meeting the transmission line safety constraint condition, if a load is still not divided into an island, dividing the load into the island on the premise of meeting the power balance constraint according to the principle of minimum side weight;
s34: and after the steps are completed, if the load is not divided into the island, removing the system and optimizing the minimum spanning tree.
Preferably, the specific steps of determining the classification of DG in the power distribution network in S1 are as follows:
s11: judging whether the classified DGs have the black start capability: the BDG has black start capability, and the NBDG does not have black start capability, so that when the power distribution network system fails, the BDG can be used as a standby power supply to participate in island operation to supply power to important loads; the NBDG cannot participate in island operation;
s12: whether it can be connected with the main network after a fault: when the power distribution network fails, the SDG type distributed power supply can be continuously connected with the power grid, and the NSDG needs to be disconnected with the power grid;
s13: whether the capacity and the control mode of communication with the control scheduling center are available: after the DG of the CDG type fails, the DG has the capacity of controlling the dispatching center to keep communication; a DG of the NCDG type does not have the capability to maintain communication with the dispatch center after a failure;
s14: and (4) comparing the DGs needing to be classified according to the characteristics of the various DGs in the steps 11 to 13, and determining the classification of the DGs in the power distribution network.
Preferably, the principle of islanding in step S2 is as follows: important load priority criterion, maximum load criterion, minimum island operation area principle and minimum network loss criterion.
Preferably, establishing an island division model of the DG-containing power distribution network specifically comprises the following steps:
the method comprises the following steps of setting an objective function of an island division model of the DG power distribution network as follows:
in the formula, P j Representing the load active power, ω, within each island i Weight representing load correspondence, n tableIndicating the number of the islands;
the constraint conditions include:
and (3) power balance constraint:
in the formula, P eq Is the total output of distributed power supply in the island, b is the node in the island, D is the node set in the island, P b The load of each node in the island is large;
safety restraint of transmission lines:
V i,min ≤V i ≤V i,max
0≤I ij 2 ≤I 2 ij,max
in the formula, V i,max 、V i,min The maximum voltage and the minimum voltage allowed by each node in the island are respectively; in the formula (4), I ij,max Then is the maximum current that the line can withstand in the island;
and (4) restraining an island radial structure:
g∈G
in the formula, G is a reconstructed network topology structure, G is a radial network topology structure set, all islands are required to be in a radial topology structure, and no loop structure exists.
Preferably, the step S4 is a specific step of establishing a fault recovery reconstruction model of the DG-containing power distribution network:
setting an objective function of a fault recovery reconstruction model:
1. maximum power supply recovery amount of important load
In the formula: l is a radical of an alcohol 1i 、L 2i 、L 3i Respectively representing three-stage load of power failure; n is 1 、n 2 、n 3 Respectively representing the number of load nodes at each level; alpha (alpha) ("alpha") 1 、α 2 、α 3 Is the importance weight coefficient of each level of load;
2. minimum number of switch actions
In the formula (f) switch The switching on and off times in the fault recovery process of the power distribution network; m is a unit of 1 、m 2 Respectively representing the number of branch switches and interconnection switches in the rest network; b is i 、C j Respectively representing the on-off states of the branch switch and the interconnection switch, and 1 and 0 respectively representing on and off; the constraints of the fault recovery reconstruction model include:
node voltage constraint:
U min ≤U i ≤U max
in the formula of U max ，U min Representing the highest and lowest voltages of nodes in the system;
current offset:
I l ≤I lmax
in the formula I lmax The maximum current which can flow on the line when the system carries out recovery reconstruction is shown;
radial structure constraint: the models after the island division are required to be of radial structures.
Preferably, the specific steps of step S5 are as follows:
s501: after the power distribution network fails, carrying out islanding according to the islanding scheme, and determining the topological structure, the switch number and the state of the rest power distribution network;
s502: switching on and off the switch under the condition of meeting the constraint, updating the structural information of the network topology, and reading a target function model for restoring the distribution network fault;
s503: determining the population size N of the chromosome, and setting the convergence precision of the first time as epsilon 1 Setting the maximum iteration times and determining the dimension of the chromosome;
s504: initializing a population based on a loop coding strategy, initializing the probabilities of all individuals to make the probabilities of all the individuals the same, and observing the population to obtain N groups of feasible solutions;
s505: substituting all feasible solutions generated in the step S504 into the adaptive value function model, solving the feasible solutions, finding the optimal adaptive value and reserving the optimal adaptive value;
s506: performing one-time rotation operation, cross operation and variation operation on the population to generate new population individuals; observing the population by using a loop coding strategy to obtain a new feasible solution;
s507: substituting the new feasible solution into the adaptive value function model, solving the adaptive value function model to find a new optimal adaptive value, comparing the new optimal adaptive value with the last optimal value, keeping a smaller optimal value, updating the optimal solution of the population, and simultaneously judging the convergence precision epsilon 1 If the conditions are still met, performing step S508 if the conditions are met, otherwise, continuing to perform step S506 and step S507;
s508: taking the result obtained in the step S507 as an initial value X0, bringing the initial value X0 into an algorithm model, initializing a positive definite matrix B0 and setting the convergence accuracy as epsilon 2 ；
S509: determining a step size λ k Search direction d k ；
S510: after the search direction is determined, the optimal approximate minimum value x is obtained k By using
Solving for g k Comparison of g k Whether or not convergence accuracy ε is satisfied 2 If the current value is less than the preset threshold value, ending the algorithm and outputting a result; otherwise, update B k And proceeds to step S509 and step S510.
The invention has the beneficial effects that: (1) By confirming the classification of DGs in the power distribution network, the power distribution network is subjected to island division by using an improved Kruskal algorithm, so that the fault can be quickly and effectively found; (2) The power supply recovery of important loads and the action times of switching are considered, and a corresponding fault recovery method is formulated by combining and applying an improved genetic algorithm, so that the power supply recovery capability of the power distribution network is greatly enhanced, and the method has practical value for the fault recovery of the power distribution network.
Drawings
Fig. 1 is a flow chart of a fault recovery method for an island division-based power distribution network including distributed power supplies according to the present invention.
Fig. 2 is a flow chart of the failure recovery strategy provided by the present invention.
Fig. 3 is a topology diagram of an IEEE33 node system with distributed power.
Fig. 4 is a schematic diagram of the reconstruction result of the distribution network after a branch failure occurs.
Fig. 5 is a schematic diagram of a reconstruction result of the power distribution network after two branches have failed.
Detailed Description
The invention is further described below with reference to the accompanying drawings. The following examples are only for illustrating the technical solutions of the present invention more clearly, and the protection scope of the present invention is not limited thereby.
As shown in fig. 1, fig. 1 is a flowchart of a fault recovery method for an islanding-based power distribution network including a distributed power supply, including S1: determining the classification of DGs in the power distribution network; s2: establishing an island division model containing a DG power distribution network according to an island division principle, the power balance of the power distribution network, the transmission line safety and an island radial structure; s3: according to the minimum spanning tree principle, obtaining an island division method by applying an improved Kruskal algorithm; s4: establishing a fault recovery reconstruction model of the power distribution network containing the DG according to the node voltage of the power distribution network, the current deviation and the isolated island radial structure; s5: and (3) according to the grade of the load in the power distribution network and the classification of DGs, carrying out optimization solution on the power distribution network reconstruction model after islanding by adopting an improved genetic algorithm to obtain a fault recovery method with the maximum important load power supply recovery amount and the minimum switching times.
Specifically, taking IEEE33 node distribution network topology as an example, with reference to fig. 2 and fig. 3, the topology has 33 nodes and 37 branches with switches, total load 3715.0kw + j2300.0kvar, reference voltage value is 12.66kV, assuming that 4 DGs are installed at nodes 6, 13, 24, and 31, and the fault occurs respectively: (1) Branch 27 (2) branch 9 and branch 22, solving with the solution of the invention:
the method comprises the following steps of firstly, determining the classification of DGs in the power distribution network, and comprising the following steps:
s11: judging whether the classified DGs have the black start capability: the BDG (Black-start DG) has Black start capability, and the NBDG (Non-Black-start DG) does not have Black start capability, so that when the power distribution network system fails, the BDG can be used as a standby power supply to participate in island operation and supply power to important loads; the NBDG cannot participate in island operation;
s12: whether it can be connected with the main network after a fault: when a power distribution network fails, the SDG (Smart Distributed Generation) can continue to be connected to the power grid, and the NSDG (Non-Smart Distributed Generation) needs to be disconnected from the power grid;
s13: whether the capacity and the control mode of communication with the control dispatching center are available: a DG (controlled Distributed Generation, controllable Distributed power) type has the capability of controlling a dispatch center to maintain communication after a fault occurs; a DG of NCDG (uncontrolled Distributed power Generation) type does not have the capability of maintaining communication with a dispatch center after a fault;
s14: referring to the characteristics of various types of DG in steps 11 to 13, comparing DG needing to be classified, and determining the classification of DG in the power distribution network, where the DG types in this embodiment are shown in table 1:
table 1 DG type and its parameters
Secondly, analyzing the principle of island division:
1. important load priority criteria:
according to the design specification GB50025-95 of power supply and distribution systems, the power loads can be divided into primary loads, secondary loads and tertiary loads according to the requirements on power supply reliability and the influence and loss caused by power supply interruption, wherein the primary loads and the secondary loads are called important loads. Therefore, the power supply of the important load should be recovered as much as possible when the islanding is performed. Active power is generally used as an optimized index;
2. maximum load criterion:
in order to ensure the reliability of power supply, when a load is brought into an island, on the premise that the load capacity does not exceed the available capacity of a DG, three-level loads as much as possible are brought into the island to ensure the minimum power loss load;
3. the minimum island operation area is easy to recover to a grid-connected operation state
Namely, the number of the splitting points in the power grid is as small as possible; as the number of islanding points decreases, the number of islanding decreases, with a consequent increase in the range of each islanding. The target can also be converted into reduction of the switching operation times, and the grid-connected operation state is easy to recover;
4. minimum loss criterion
Since the capacity of the distributed power supply is fixed, in the process of remote power transmission, in order to ensure the economy and reliability of the operation of the power system, the principle of minimum network loss should be considered as much as possible when the power system operates in an island.
And thirdly, establishing an island division model of the DG-containing power distribution network, wherein the constraint conditions of the model comprise power balance constraint, transmission line safety constraint and island radial structure constraint. The method comprises the following steps:
the method comprises the following steps of setting an objective function of an island division model of the DG power distribution network as follows:
in the formula, P j Representing the load active power, ω, within each island i Representing the weight corresponding to the load, and n represents the number of the islands;
the constraint conditions include:
and (3) power balance constraint:
in the formula, P eq B is a node in the island, D is a node set in the island, and P is the total output of the distributed power supply in the island b The load of each node in the island is large;
safety restraint of transmission lines:
V i,min ≤V i ≤V i,max
0≤I ij 2 ≤I 2 ij,max
in the formula, V i,max 、V i,min The maximum voltage and the minimum voltage allowed by each node in the island are respectively; in the formula (4), I ij,max Then is the maximum current that the line can withstand in the island;
and (4) restraining an island radial structure:
g∈G
in the formula, G is a reconstructed network topology structure, G is a radial network topology structure set, all islands are required to be in a radial topology structure, and no loop structure exists.
Fourthly, according to the minimum spanning tree principle, an island division scheme is obtained by applying an improved Kruskal algorithm, and the method specifically comprises the following steps:
s31: accessing all DGs into a power grid, searching from top to bottom according to the bus numbers, and for buses which are not directly connected with DG nodes, accessing the DG nodes closest to the access points according to the DG weight to form an initial island;
s32: under the condition of meeting the power balance constraint, sequentially merging the first-level load, the second-level load and the third-level load which are divided according to the load grade into each island, checking the constraint condition once when each load is accessed, simultaneously ensuring the load maximization, and sequentially traversing each island;
s33: under the condition of meeting the transmission line safety constraint condition, if a load is still not divided into an island, dividing the load into the island on the premise of meeting the power balance constraint according to the principle of minimum side weight;
s34: after the steps are completed, if the load is still not divided into the island, the system is removed, and the minimum spanning tree is optimized; the islanding result of this embodiment is shown in table 2:
table 2 islanding results
| Load points within an optimal island | Total load in island | | |
| DG2 | |||
| 13，12，11，15，14，10 | 465kW+j320kvar | S10, | |
| DG3 | |||
| 22，23，24 | 1060kW+ | S22 | |
| DG4 | |||
| 29，30，31，32 | 620kW+j660kvar | S29 |
And fifthly, establishing a fault recovery reconstruction model of the DG-containing power distribution network, wherein the model comprises a target function and constraint conditions, the constraint conditions comprise node voltage constraint, current offset constraint and radial structure constraint, and the method comprises the following specific steps of:
setting an objective function of a fault recovery reconstruction model:
1. maximum power supply recovery amount of important load
In the formula: l is 1i 、L 2i 、L 3i Respectively representing three-stage load of power failure; n is a radical of an alkyl radical 1 、n 2 、n 3 Respectively representing the number of load nodes at each level; alpha (alpha) ("alpha") 1 、α 2 、α 3 Is the importance weight coefficient of each level of load;
2. minimum number of switch actions
In the formula, f switch The switch on-off times in the fault recovery process of the power distribution network; m is 1 、m 2 Respectively representing the number of branch switches and interconnection switches in the rest network; b is i 、C j Respectively representing the on-off states of the branch switch and the interconnection switch, and 1 and 0 respectively representing on and off; the constraints of the fault recovery reconstruction model include:
node voltage constraint:
U min ≤U i ≤U max
in the formula of U max ，U min Representing the highest voltage and the lowest voltage of nodes in the system;
current offset:
I l ≤I l max
in the formula I l max The maximum current which can flow on the line when the system carries out recovery reconstruction is shown;
and (3) radial structure constraint: the models after islanding are required to be radial structures.
Sixthly, considering grade division of the loads in the power distribution network and classification of DGs, and performing optimization solution on a power distribution network reconstruction scheme after island division by adopting an improved genetic algorithm to obtain a fault recovery scheme with the maximum important load power supply recovery amount and the minimum switching times, wherein the method specifically comprises the following steps:
s501: after the power distribution network fails, carrying out islanding according to the islanding scheme, and determining the topological structure, the switch number and the state of the rest power distribution network;
s502: switching on and off the switch under the condition of meeting the constraint, updating the structural information of the network topology, and reading a target function model for restoring the distribution network fault;
s503: determining the population size N of the chromosome, and setting the convergence precision of the first time as epsilon 1 Setting the maximum iteration times and determining the dimension of the chromosome;
s504: initializing a population based on a loop coding strategy, initializing the probabilities of all individuals to make the probabilities of all the individuals the same, and observing the population to obtain N groups of feasible solutions;
s505: substituting all feasible solutions generated in the step S504 into the adaptive value function model, solving the adaptive value function model, finding the optimal adaptive value and reserving the optimal adaptive value;
s506: performing one-time rotation operation, cross operation and mutation operation on the population to generate a new population individual; observing the population by using a loop coding strategy to obtain a new feasible solution;
s507: substituting the new feasible solution into the adaptive value function model, solving the adaptive value function model to find a new optimal adaptive value, comparing the new optimal adaptive value with the last optimal value, keeping a smaller optimal value, updating the optimal solution of the population, and simultaneously judging the convergence precision epsilon 1 If the requirements are still met, performing step S508 if the requirements are met, otherwise, continuing to perform step S506 and step S507;
s508: taking the result obtained in the step S507 as an initial value X0, bringing the initial value X0 into an algorithm model, initializing a positive definite matrix B0 and setting the convergence accuracy as epsilon 2 ；
S509: determining a step size λ k Search direction d k ；
S510: after the search direction is determined, the optimal approximate minimum value x is solved k By using
Solving for g k Comparison g k Whether or not convergence accuracy ε is satisfied 2 If the current value is less than the preset value, ending the algorithm and outputting a result; otherwise, update B k And continues with step S509 and step S510; the faults occur respectively at: (1) branch 27 (2) branch 9 and branch 22; the recovery strategy results for both failure cases are shown in tables 3 and 4:
table 3 failure 1 system recovery reconstruction results
Table 4 failure 2 system recovery reconstruction results
According to the data in the table, the fault recovery capability of the power distribution network can be effectively improved by reconstructing a fault recovery repeating scheme based on islanding. The important load recovery power supply rate is the highest, the lowest node voltage is ideally improved, and the action times of the switch in the whole reconstruction process are the least.
After the power distribution network is subjected to islanding by using the improved Kruskal algorithm, the power distribution network is reconstructed by taking the power supply recovery of the maximum important load and the action times of the minimum switch as objective functions and taking node voltage constraint, line current constraint and network topology constraint as constraint conditions, so that the power supply recovery of the power distribution network is realized, and the power quality of the system is improved.
The above embodiment is only a preferred embodiment of the present invention, and is not intended to limit the present invention in any way, and other variations and modifications may be made without departing from the technical scope of the claims.
Claims (7)
1. A fault recovery method for a power distribution network with distributed power supplies based on islanding comprises the following steps:
s1: determining the classification of DGs in the power distribution network;
s2: establishing an island division model containing the DG power distribution network according to an island division principle, the power balance of the power distribution network, the transmission line safety and an island radial structure;
s3: according to the minimum spanning tree principle, an island division method is obtained by applying an improved Kruskal algorithm;
s4: establishing a fault recovery reconstruction model containing the DG power distribution network according to the node voltage of the power distribution network, the current deviation and the isolated island radial structure;
s5: and (3) according to the grade of the load in the power distribution network and the classification of DGs, carrying out optimization solution on the power distribution network reconstruction model after islanding by adopting an improved genetic algorithm to obtain a fault recovery method with the maximum important load power supply recovery amount and the minimum switching times.
2. The method for recovering the fault of the power distribution network including the distributed power supply based on the islanding, according to claim 1, wherein the specific step in the step S3 is:
s31: accessing all DGs into a power grid, searching from top to bottom according to the bus numbers, and for buses which are not directly connected with DG nodes, accessing the DG nodes closest to the access points according to the DG weight to form an initial island;
s32: under the condition of meeting the power balance constraint, sequentially merging the first-level load, the second-level load and the third-level load which are divided according to the load grades into each island, checking the constraint condition once when one load is accessed, ensuring the maximization of the load, and sequentially traversing each island;
s33: under the condition of meeting the transmission line safety constraint condition, if a load is still not divided into an island, dividing the load into the island on the premise of meeting the power balance constraint according to the principle of minimum side weight;
s34: and after the steps are completed, if the load is not divided into the island, removing the system and optimizing the minimum spanning tree.
3. The method for recovering the fault of the power distribution network with the distributed power supply based on the islanding is characterized in that the specific steps of determining the classification of the DGs in the power distribution network in the S1 are as follows:
s11: judging whether the DGs needing to be classified are provided with black start capability: the BDG has black start capability, and the NBDG does not have black start capability, so that when the power distribution network system fails, the BDG can be used as a standby power supply to participate in island operation to supply power to important loads; the NBDG cannot participate in island operation;
s12: whether it can be connected with the main network after a fault: when the power distribution network fails, the SDG type distributed power supply can be continuously connected with the power grid, and the NSDG needs to be disconnected with the power grid;
s13: whether the capacity and the control mode of communication with the control scheduling center are available: after the DG of the CDG type fails, the DG has the capacity of controlling the dispatching center to keep communication; a DG of the NCDG type does not have the capability to maintain communication with the dispatch center after a failure;
s14: and (4) comparing the DGs needing to be classified according to the characteristics of the various DGs in the steps 11 to 13, and determining the classification of the DGs in the power distribution network.
4. The method according to claim 1, wherein the principle of islanding in step S2 includes: important load priority criterion, maximum load criterion, minimum island operation area principle and minimum network loss criterion.
5. The method for recovering the fault of the power distribution network including the distributed power supply based on the islanding is characterized in that the establishing of the islanding model including the DG power distribution network specifically comprises the following steps:
setting the target function of the island division model of the DG power distribution network as follows:
in the formula, P j Representing the load active power, ω, within each island i Representing the weight corresponding to the load, wherein n represents the number of the islands;
the constraint conditions include:
and (3) power balance constraint:
in the formula, P eq Is the total output of distributed power supply in the island, b is the node in the island, D is the node set in the island, P b The load of each node in the island is large;
transmission line safety constraints:
V i,min ≤V i ≤V i,max
0≤I ij 2 ≤I 2 ij,max
in the formula, V i,max 、V i,min The maximum voltage and the minimum voltage allowed by each node in the island are respectively; in the formula (4), I ij,max Then is the maximum current that the line can withstand in the island;
and (4) restraining an island radial structure:
g∈G
in the formula, G is a reconstructed network topology structure, G is a radial network topology structure set, all islands are required to be in a radial topology structure, and no loop structure exists.
6. The method according to claim 3, wherein the step S4 of establishing the fault recovery reconstruction model of the DG-containing power distribution network comprises the specific steps of:
setting an objective function of the fault recovery reconstruction model:
1. maximum power supply recovery amount of important load
In the formula: l is a radical of an alcohol 1i 、L 2i 、L 3i Respectively representing three-stage load of power failure; n is a radical of an alkyl radical 1 、n 2 、n 3 Respectively representing the number of load nodes at each level; alpha is alpha 1 、α 2 、α 3 Is the importance weight coefficient of each level of load;
2. minimum number of switch actions
In the formula, f switch The switching on and off times in the fault recovery process of the power distribution network; m is 1 、m 2 Respectively representing the number of branch switches and interconnection switches in the rest network; b is i 、C j Respectively representing the on-off states of the branch switch and the interconnection switch, and 1 and 0 respectively representing on and off; the constraint conditions of the fault recovery reconstruction model comprise:
node voltage constraint:
U min ≤U i ≤U max
in the formula of U max ，U min Representing the highest and lowest voltages of nodes in the system;
current offset:
I l ≤I lmax
in the formula I lmax The maximum current which can flow on the line when the system carries out recovery reconstruction is shown;
and (3) radial structure constraint: the models after the island division are required to be of radial structures.
7. The method for recovering the fault of the power distribution network including the distributed power supply based on the islanding, according to claim 6, wherein the specific steps of the step S5 are as follows:
s501: after the power distribution network fails, carrying out islanding according to the islanding scheme, and determining the topological structure, the switch number and the state of the rest power distribution network;
s502: switching on and off the switch under the condition of meeting the constraint, updating the structural information of the network topology, and reading a target function model for restoring the distribution network fault;
s503: determining the population size N of the chromosome, and setting the convergence precision of the first time as epsilon 1 Setting the maximum iteration times and determining the dimension of the chromosome;
s504: initializing a population based on a loop coding strategy, initializing the probabilities of all individuals to make the probabilities of all the individuals the same, and observing the population to obtain N groups of feasible solutions;
s505: substituting all feasible solutions generated in the step S504 into the adaptive value function model, solving the feasible solutions, finding the optimal adaptive value and reserving the optimal adaptive value;
s506: performing one-time rotation operation, cross operation and variation operation on the population to generate new population individuals; observing the population by using a loop coding strategy to obtain a new feasible solution;
s507: substituting the new feasible solution into the adaptive value function model, solving the adaptive value function model to find a new optimal adaptive value, comparing the new optimal adaptive value with the last optimal value, keeping a smaller optimal value, updating the optimal solution of the population, and simultaneously judging the convergence precision epsilon 1 If the conditions are still met, performing step S508 if the conditions are met, otherwise, continuing to perform step S506 and step S507;
s508: taking the result obtained in the step S507 as an initial value X0, bringing the initial value X0 into an algorithm model, initializing a positive definite matrix B0 and setting the convergence accuracy as epsilon 2 ；
S509: determining the step size lambda k Search direction d k ；
S510: after the search direction is determined, the optimal approximate minimum value x is solved k By using
Solving for g k Comparison g k Whether or not convergence accuracy ε is satisfied 2 If the current value is less than the preset value, ending the algorithm and outputting a result; otherwise, update B k And continues with step S509 and step S510.
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Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
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| CN116388185A (en) * | 2023-06-05 | 2023-07-04 | 昆明理工大学 | Active power distribution network fault processing and rapid self-healing method and system |
| CN117239939A (en) * | 2023-11-15 | 2023-12-15 | 国网浙江省电力有限公司宁波供电公司 | Distribution automation protection method realized by cooperation of master station and distributed terminal |
| CN117458444A (en) * | 2023-10-19 | 2024-01-26 | 湖南科技大学 | Power distribution network power supply recovery method based on intelligent soft switch |
| CN117674115A (en) * | 2023-12-05 | 2024-03-08 | 国网四川省电力公司 | Method and system for recovering power supply load after fault of power distribution network containing distributed power supply |
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| Publication number | Priority date | Publication date | Assignee | Title |
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| CN116388185A (en) * | 2023-06-05 | 2023-07-04 | 昆明理工大学 | Active power distribution network fault processing and rapid self-healing method and system |
| CN116388185B (en) * | 2023-06-05 | 2023-09-12 | 昆明理工大学 | Active power distribution network fault processing and rapid self-healing method and system |
| CN117458444A (en) * | 2023-10-19 | 2024-01-26 | 湖南科技大学 | Power distribution network power supply recovery method based on intelligent soft switch |
| CN117239939A (en) * | 2023-11-15 | 2023-12-15 | 国网浙江省电力有限公司宁波供电公司 | Distribution automation protection method realized by cooperation of master station and distributed terminal |
| CN117239939B (en) * | 2023-11-15 | 2024-04-02 | 国网浙江省电力有限公司宁波供电公司 | Distribution automation protection method realized by cooperation of master station and distributed terminal |
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