CN115062931B - Method for building power failure time function of load on power distribution network automation terminal - Google Patents

Abstract

The method for constructing a power outage time function of a load on a distribution network automation terminal is constructed based on a logical operator and specifically includes the following steps: Step 1: constructing a general model of load power outage time that only considers a manual disconnector x; Step 2: constructing a general model of load power outage time that considers a manual disconnector x and a fault indicator y; Step 3: constructing a general model of load power outage time that simultaneously considers a manual disconnector x and a fault indicator y as well as an automatic disconnector z. The purpose of the present invention is to adapt to a distribution network with an increasingly complex structure, an increasingly diversified operation mode, and an increasingly diverse type of automation terminals, so as to enable a complete and stable automation operation of the distribution network.

Description

Method for constructing the power outage time function of load on distribution network automation terminal

Technical Field

The present invention belongs to the field of power system planning, and specifically relates to a method for building a power outage time function of a load regarding a distribution network automation terminal. The present invention is a divisional application of an invention patent with the invention name "A method for optimizing configuration of distribution network automation terminals" and application number 2021100844931.

Background technique

With the continuous development of social economy, users have higher and higher demands for the reliability of power supply in distribution network. By introducing various types of distribution network automation terminals, fault isolation can be quickly realized, fault location can be accelerated, and load transfer can be performed, which can minimize the power outage losses caused by permanent faults and the power outage time of users, and is the most effective means to improve the reliability of distribution network.

In the prior art, a method for optimizing the configuration of distribution network terminals is disclosed in a patent document with authorization announcement number CN201611215510. The patent conducts an in-depth study on the installation type, quantity and location of distribution network terminals, and conducts an observability analysis on the configuration of distribution terminals on the basis of ensuring power supply reliability, thereby achieving observability of the distribution network and reducing the risk of unobservability of the distribution network.

However, this type of existing technology does not take into account the accelerating effect of various distribution network automation terminals on fault line inspection, which leads to a certain gap between the existing technology and the actual reliability calculation, resulting in the inability to obtain the global optimal solution, and ultimately leading to economic waste.

Domestic power grids have started the construction and promotion of distribution network automation since the last century. However, due to the complex structure of the distribution network, various operation modes, and various types of automation terminals, how to make full use of the limited resources to play the role of distribution network automation is the most important issue in the construction of distribution network automation. Therefore, it is necessary to build a set of distribution network automation terminal optimization configuration methods.

Summary of the invention

The purpose of the present invention is to provide an optimization configuration method for distribution network automation terminals in order to adapt to distribution networks with increasingly complex structures, increasingly diverse operating modes, and increasingly numerous types of automation terminals, so as to enable the distribution network to operate completely and stably.

In order to solve the above technical problems, the technical solution adopted by the present invention is:

A method for building a power outage time function of a load on a distribution network automation terminal is built based on a logical operator and specifically includes the following steps:

Step 1: Build a general model of load outage time considering only the manual disconnector x;

Step 2: Build a general model of load outage time considering manual disconnector x and fault indicator y;

Step 3: Build a general model of load outage time that takes into account manual disconnector x, fault indicator y, and automatic disconnector z.

In step 1, the general expression of the load power outage time of the manual disconnector x is:

Where: Xi _,j is the set of x variables between fault i and load j on feeder f; It is the determination operator of the manual disconnect switch action time; is the determination operator for the maintenance time; t ^search is the fault line patrol constant of the feeder, which is related to the total length of the medium-voltage section and the low-voltage section of the feeder; t ^mcs is the manual disconnector action time constant; t ^rep is the fault repair time constant.

In step 2, the general expression of load power outage time considering the manual disconnector x and the fault indicator y is:

v _a (x, y) = And (Or (Y _{i, a} ), Or (X _{j, a} ))

Where: is the judgment operator for judging that there is no fault indicator between section s and fault i; Yi _,s is the set of y variables between fault i and section s on feeder f; is the patrol time of section s; Ω _s is the section set; _va (*x,y) is the auxiliary variable of the switch installation candidate position, which is used to determine whether the manual disconnector on the load side of the switch installation candidate position a _n and the fault indicator on the fault side exist at the same time; Yi _,a is the set of y variables between fault i on feeder f and switch installation candidate position a _n ; Xj _,a is the set of x variables between load j on feeder f and switch installation candidate position a _n ; is an operator used to determine whether load j needs to undergo line inspection time; Vi _,j (x,y) is the set of all auxiliary variables _va (x,y) between fault i and load j.

In step 3, the general expression of the load outage time considering the manual disconnector x, fault indicator y and automatic disconnector z is:

Where: t ^rcs is the action time of the automatic disconnector.

A method for building a distribution network automation terminal optimization configuration model includes the following steps:

Step 1) Building a general model of power outage losses related to distribution network automation terminals;

Step 2) Building a general model of capital investment related to distribution network automation terminals;

Step 3) Build a distribution network automation terminal optimization configuration model with the goal of minimizing the sum of power outage losses and capital investment and capital investment as a constraint.

In step 1),

After the distribution network is out of power due to a fault, all the electricity sales fees lost by the power sales company during the power outage time are regarded as the power outage loss on the grid side. The mathematical expression is:

Where: Ω _f,i is the set of faults i on feeder f; Ω _f,j is the set of loads j on feeder f; Ω _j,k is the set of all load types at load point j; λ _i is the expected probability of fault i; P _t,k is the load of the kth type of load in the tth year; R _k is the unit electricity price of the kth type of load;

The user's loss during the power outage time after the distribution network is out of power due to a fault is regarded as the user-side power outage loss, and its mathematical expression is:

Where: CDF _k (·) is the power outage loss function;

The total power outage loss, that is, the sum of the power outage loss on the grid side and the power outage loss on the load side, is taken as one of the optimization objectives, and its mathematical expression is:

CIC(x,y,z)＝GCIC(x,y,z)+LCIC(x,y,z).

In step 2), the primary investment cost is the sum of the primary investment costs of all automation terminals on all feeders of the entire distribution network, and its mathematical expression is:

Where: Ω _f is the set of feeders in the distribution network; Ω _f,a ,Ω _f,d are the candidate installation locations of disconnectors and fault indicators on feeder f; inv ^MCS , inv ^FI and inv ^RCS are the primary investment costs of manual disconnectors, fault indicators and automatic disconnectors, respectively;

The later maintenance cost is the sum of the maintenance costs during the entire service life of the automation terminal, and its mathematical expression is:

Where: Ω _t is the expected service life of the automation terminal; DR is the maintenance fee discount rate;

The whole life cycle cost, i.e. the sum of the one-time investment cost and the subsequent maintenance cost, is taken as one of the optimization objectives and constraints, and its general expression is given.

In step 3), the optimization goal is to minimize the sum of power outage losses caused by permanent faults and capital investment under limited capital investment. The corresponding optimization model is as follows:

minimize CIC(x,y,z)+LCC(x,y,z)

Where: LCC ^lim is the upper limit of the life cycle cost;

Install the same type of isolating switches at the same isolating switch mounting location.

A method for optimizing the configuration of a distribution network automation terminal comprises the following steps:

Step 1: Propose a logical operator that considers the AND or OR relationship;

Step 2: Build a power outage time function of the load on the distribution network automation terminal based on the logical operator;

Step 3: Based on the power outage time function, the optimal configuration of distribution network automation terminals is established with the goal of minimizing the sum of power outage losses and capital investment and capital investment as a constraint;

Step 4: Solve the optimal configuration solution based on the optimization configuration model.

In step 1, the following steps are specifically included:

Step 1) Define a set of variables.

VAR = {var _i |i∈Ω _index };

Where: variable var _i is the decision Boolean variable of this paper. Its value is 1, which means that the corresponding automation terminal is configured at position i, and its value is 0, which means that the corresponding automation terminal is not configured. Ω _index is the set of subscripts that meet certain conditions. VAR is the set of variables whose subscripts meet certain conditions;

Step 2) define the logical AND operator And(·) and the logical OR operator Or(·) for operating on the variable set;

In step 2, the above method of constructing a power outage time function of the load with respect to the distribution network automation terminal is adopted.

In step 3, the above method of building a distribution network automation terminal optimization configuration model is adopted.

In step 4, an improved island parallel genetic algorithm is used to solve the optimal configuration solution. In the island model, multiple independent initial populations are used and assigned to each thread. Each population adopts its own evolutionary process and explores in its own search space. The migration mechanism is used between populations to realize information exchange.

Compared with the prior art, the present invention has the following technical effects:

The present invention can well adapt to the distribution network with increasingly complex structure, increasingly diversified operation modes and increasingly numerous types of automation terminals, and can enable the distribution network to operate more completely and stably.

BRIEF DESCRIPTION OF THE DRAWINGS

The present invention will be further described below in conjunction with the accompanying drawings and embodiments:

FIG1 is an execution flow chart of an improved island parallel genetic algorithm;

FIG2 is a flow chart of the configuration in the present invention;

Figure 3 is a topological diagram of the test system;

Figure 4 is a graph showing the change in the number of distribution network automation terminals;

Figure 5 is a graph showing the change in target value.

Detailed ways

A method for optimizing configuration of a distribution network automation terminal comprises the following steps:

Step 1: Propose a set of logical operators that consider AND or OR relationships;

Step 2: Based on the logical operator in step 1, build a power outage time function of the load on the distribution network automation terminal;

Step 3: Based on the power outage time function in step 2, a distribution network automation terminal optimization configuration model is constructed with the goal of minimizing the sum of power outage losses and capital investment and capital investment as a constraint;

Step 4: Based on the optimization configuration model in step 3, an improved island parallel genetic algorithm is used to solve and obtain the optimal configuration solution;

In step 1, the following steps are specifically included:

Step 1) Define a set of variables.

VAR＝{var _i |i∈Ω _index }

Where: variable var _i is the decision Boolean variable of this paper. Its value is 1, which means that the corresponding automation terminal is configured at position i, and its value is 0, which means that the corresponding automation terminal is not configured. Ω _index is the set of subscripts that meet certain conditions. VAR is the set of variables whose subscripts meet certain conditions.

Step 2) Define the logical AND operator And(·) and the logical OR operator Or(·) for operating on a set of variables.

In step 2, the following steps are specifically included:

Step 1) construct a general expression for the load outage time considering only the manual disconnector x;

Where: Xi _,j is the set of x variables between fault i and load j on feeder f; It is the determination operator of the manual disconnect switch action time; is the determination operator for the maintenance time; t ^search is the fault line patrol constant of the feeder, which is related to the total length of the medium-voltage section and the low-voltage section of the feeder; t ^mcs is the manual disconnector action time constant; t ^rep is the fault repair time constant

Step 2) Construct a general expression for the load outage time considering the manual disconnector x and the fault indicator y:

v _a (x, y) = And (Or (Y _{i, a} ), Or (X _{j, a} ))

Where: is the judgment operator for judging that there is no fault indicator between section s and fault i; Yi _,s is the set of y variables between fault i and section s on feeder f; is the patrol time of section s; Ω _s is the section set; _va (x, y) is the auxiliary variable of the switch installation candidate position, which is used to determine whether the manual disconnector on the load side of the switch installation candidate position a _n and the fault indicator on the fault side exist at the same time; Yi _,a is the set of y variables between fault i on feeder f and switch installation candidate position a _n ; Xj _,a is the set of x variables between load j on feeder f and switch installation candidate position a _n ; is an operator used to determine whether load j needs to go through line inspection time; Vi _,j (x,y) is the set of all auxiliary variables _va (x,y) between fault i and load j;

Step 3) Construct a general expression for the load outage time that takes into account the manual disconnector x, fault indicator y, and automatic disconnector z:

Where: t ^rcs is the action time of the automatic disconnector.

In step 3, the following steps are specifically included:

Step 1) Establish a general expression for power outage losses related to distribution network automation terminals.

This patent regards all the electricity sales fees lost by the power sales company during the power outage time after the distribution network is out of power due to a fault as the power outage loss on the grid side, and its mathematical expression is:

Where: Ω _f,i is the set of faults i on feeder f; Ω _f,j is the set of loads j on feeder f; Ω _j,k is the set of all load types at load point j; λ _i is the expected probability of fault i; P _t,k is the load of the kth type of load in the tth year; R _k is the unit electricity price of the kth type of load;

This patent regards the loss of users during the power outage time after the distribution network is out of power due to a fault as the power outage loss on the user side, and its mathematical expression is:

Where: CDF _k (·) is the power outage loss function

In this patent, the total power outage loss, that is, the sum of the power outage loss on the grid side and the power outage loss on the load side, is taken as one of the optimization targets, and its mathematical expression is:

CIC(x,y,z)＝GCIC(x,y,z)+LCIC(x,y,z)

Step 2) Establish a general expression for capital investment related to distribution network automation terminals.

The one-time investment cost in this patent is the sum of the one-time investment costs of all automation terminals on all feeders of the entire distribution network, and its mathematical expression is:

Where: Ω _f is the set of feeders in the distribution network; Ω _f,a ,Ω _f,d are the candidate installation locations of disconnectors and fault indicators on feeder f; inv ^MCS , inv ^FI and inv ^RCS are the primary investment costs of manual disconnectors, fault indicators and automatic disconnectors, respectively;

The late maintenance cost in this patent is the sum of the maintenance costs during the entire service life of the automation terminal, and its mathematical expression is:

Where: Ω _t is the expected service life of the automation terminal; DR is the maintenance fee discount rate.

In this patent, the whole life cycle cost, i.e., the sum of the one-time investment cost and the subsequent maintenance cost, is taken as one of the optimization objectives and constraints, and its general expression.

Step 3) Build a distribution network automation terminal optimization configuration model with the goal of minimizing the sum of power outage losses and capital investment and capital investment as a constraint.

This patent is dedicated to minimizing the sum of power outage losses and capital investment caused by permanent faults with limited capital investment. The corresponding optimization model is as follows:

minimize CIC(x,y,z)+LCC(x,y,z)

Where: LCC ^lim is the upper limit of the life cycle cost. Considering that the installation candidate locations of the manual disconnector and the automatic disconnector are the same, an installation constraint is added, that is, only one type of disconnector can exist at the same disconnector installation location.

Step 4 includes:

In the island model, in order to enhance randomness, multiple independent initial populations are used and assigned to each thread. Each population uses its own evolution process to explore in its own search space. While ensuring computational efficiency, a migration mechanism is used between populations to achieve information exchange. To further improve the efficiency of the algorithm, an adaptive adjustment phase is added to the algorithm flow. This phase strengthens the balance ability during the search process. In this phase, the individuals with the highest fitness will be used for taboo search, and the individuals with the lowest fitness will be subjected to global search. The flowchart is shown in Figure 1.

Example:

This patent adopts the IEEE RBTS-BUS4 distribution network system as the distribution network system for testing, and its topology is shown in FIG3 .

The distribution system has a total of 7 feeders, 38 load nodes, 241 candidate terminal locations of various types, 4,779 users, and a total average load of 24.58MW.

It can be found that if a general brute force algorithm is used to solve the problem, there are ^2,241 possible solutions, which will lead to dimensionality disaster. On the other hand, the model is also suitable for verifying the effectiveness of the model proposed in this patent.

The relevant parameters used in this patent are as follows:

Table 1 Time parameters

Table 2 Price parameters

Where _R1 , _R2 and _R3 are the unit electricity prices of residential load, commercial load and industrial load respectively.

Table 3 Fault type parameters

Among them, p ^low , v ^low , p ^mid and v ^mid are the fault probability coefficients and line inspection speeds of the low-voltage section and medium-voltage section respectively, and p ^T is the failure probability of the medium-voltage transformer.

Table 4 Solution class parameters

Table 5 Power outage loss coefficients for various types of loads

The solution results are shown in Figures 4 and 5.

For Figure 4, as LCC continues to increase, it can be found that:

Manual disconnect switches were deployed first, reaching a peak of 15 at around 2,000,000, then declining and reaching a second peak at around 4,500,000, and finally falling to 0.

For the fault indicator, it has been in a state of relatively large fluctuations. The peaks and valleys of its quantity curve overlap with those of the manual disconnect switch to a large extent. However, unlike the manual disconnect switch, it finally remains at 38.

Since automatic disconnectors are the most expensive, they are not deployed in the distribution network when the LCC is small. However, as the LCC increases, the number of automatic disconnectors gradually increases and eventually stabilizes at 51.

For Figure 5, it can be found that the comprehensive cost will reach a minimum value. By observing the figure, it can be found that this is because when the LCC is small, the power outage loss is relatively large. Although the power outage loss can be reduced by increasing the LCC, according to the above analysis, the power outage loss has a saturation characteristic. When it is reduced to a certain value, the LCC continues to increase, and the power outage loss basically no longer decreases, resulting in an increase in the comprehensive cost.

The above results fully demonstrate the rationality and effectiveness of the optimization configuration method for distribution network automation terminals proposed in this patent.

Claims (1)

1. The method for constructing the power failure time function of the load on the power distribution network automation terminal is characterized by comprising the following steps of:

step 1: building a load power failure time general term model only considering the manual isolating switch x;

Step 2: building a load power failure time general term model taking the manual isolating switch x and the fault indicator y into consideration;

Step 3: building a load power failure time general term model which simultaneously considers the manual isolating switch x and the fault indicator y and automatically isolates the switch z;

In step 1, the load outage time general term expression of the manual isolating switch x is:

wherein: x _i,j is the set of X variables between fault i to load j on feeder f; is a judging operator related to the action time of the manual isolating switch; is a decision operator regarding maintenance time; t ^search is the fault line patrol constant of the feeder f, and is related to the total length of the medium-voltage section and the low-voltage section of the feeder f; t ^mcs is the action time constant of the manual isolating switch; t ^rep is a fault maintenance time constant;

in step2, consider the load outage time general expression for the manual disconnector x and fault indicator y as:

v_a(x,y)＝And(Or(Y_i,a),Or(X_j,a))

Wherein: Is a judging operator for judging that no fault indicator exists between the section s and the fault i; y _i,s is the set of Y variables between fault i to section s on feeder f; Line patrol time for section s; omega _s is the set of segments; v _a (x, y) is a switch installation candidate position auxiliary variable for determining whether a manual disconnecting switch on the load side of the switch installation candidate position a _n is present simultaneously with the fault indicator on the fault side; y _i,a is the set of Y variables between fault i on feeder f to switch installation candidate position a _n; x _j,a is the set of X variables between the load j on the feeder f to the switch installation candidate position a _n; Is an operator for determining whether the load j needs to go through line patrol time; v _i,j (x, y) is the set of all auxiliary variables V _a (x, y) between fault i to load j;

In step 3, the load outage time general term expressions of the manual disconnecting switch x, the fault indicator y and the automatic disconnecting switch z are considered at the same time, and are as follows:

Wherein: t ^rcs is the action time of the automatic isolating switch;

the logical operator is defined by:

step 1) defining a variable set:

VAR＝{var_i|i∈Ω_index}；

Wherein: the variable VAR _i is a decision Boolean variable, the value of which is 1 represents that a corresponding automatic terminal is configured at the i position, the value of which is 0 represents that a corresponding automatic terminal is not configured, omega _index is a subscript set meeting a specific condition, and VAR is a variable set of which the subscript meets the specific condition;

step 2) defining a logical AND operator And a logical OR operator;