Site selection method and device for phase-shifting transformer
By performing power flow analysis and multi-objective function optimization in the power system, and combining particle swarm optimization and genetic algorithms to dynamically adjust weights, the problem of phase-shifting transformer location was solved, thereby improving the stability and economy of the power grid.
Patent Information
- Application Number
- CN202510886214.1
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-06-30
- Publication Date
- 2025-11-28
AI Technical Summary
In power systems, existing technologies make it difficult to scientifically select and optimize the installation location of phase-shifting transformers, which may lead to problems such as power shift, line overload and voltage imbalance in the power grid. Moreover, phase-shifting transformers are expensive, and it is difficult to determine the optimal installation location based solely on empirical methods or simple power flow calculations.
By performing power flow analysis on the target power area, a multi-objective function is established with the objectives of balancing line load, minimizing system losses, and minimizing the installation cost of phase-shifting transformers. Combining particle swarm optimization and genetic algorithms, the weights are dynamically adjusted, and constraints such as frequency stability, node voltage, and line thermal stability are considered to solve the overall objective function and determine the optimal connection location of the phase-shifting transformer.
It enables the rapid and accurate determination of the optimal installation location of the phase-shifting transformer, optimizes power flow, improves power grid stability and economy, and reduces equipment losses and costs.
Smart Images
Figure CN121032016A_ABST
Abstract
Description
TECHNICAL FIELD
[0001] The present application relates to the technical field of power systems, and in particular to a method and device for site selection of a phase-shifting transformer. BACKGROUND
[0002] With the increasing penetration of distributed energy and renewable energy in power systems, the complexity of power grid operation is gradually increasing. The current and voltage distribution of the traditional power system is relatively uniform, but due to the randomness and volatility of new energy output, the power flow distribution and power transmission path in the power grid are more complex, and local power grids may have serious power deviation, line overload, voltage imbalance and other problems. The phase-shifting transformer (PST) can change the voltage phase angle relationship and flexibly guide the power flow of the power grid. In order to effectively regulate the power flow, one of the key points is how to scientifically select and optimize the installation position of the phase-shifting transformer in the entire power grid system.
[0003] The site selection of ordinary transformers is often based on voltage level requirements, load center distribution and geographical constraints to meet the requirements of power supply reliability and power transmission efficiency. However, the site selection of phase-shifting transformers is more complex, and the cost of phase-shifting transformers is high and the installation position is limited. It is difficult to determine the optimal installation position of the phase-shifting transformer by relying on experience or simple power flow calculation. SUMMARY
[0004] The embodiments of the present application provide a method and device for site selection of a phase-shifting transformer to improve the accuracy of site selection of the phase-shifting transformer and accurately determine the optimal installation position of the phase-shifting transformer.
[0005] In a first aspect, the embodiments of the present application provide a method for site selection of a phase-shifting transformer, comprising:
[0006] performing power flow analysis on a target power region to determine candidate installation positions of the phase-shifting transformer in the target power region;
[0007] establishing a multi-objective function with the line load balancing of the target power region, the minimum system loss of the target power region and the minimum installation cost of the phase-shifting transformer as targets;
[0008] determining a total objective function according to a preset rated value of load balancing in the target power region, a system expected loss value of the target power region, an installation budget value of the phase-shifting transformer and the multi-objective function;
[0009] establishing a constraint condition of the total objective function;
[0010] Solving the total target function based on the constraint condition and the alternative installation position of the shunt transformer to obtain an optimal access position of the shunt transformer in the target power area.
[0011] In a possible implementation, the total target function is determined according to the preset rated value of load balancing in the target power area, the system expected loss value of the target power area, the installation budget value of the shunt transformer, and the multi-target function, and includes:
[0012] According to the rated value, the system expected loss value, the installation budget value, and the multi-target function, a weight coefficient corresponding to each function in the multi-target function is determined.
[0013] Based on the weight coefficient corresponding to each function, a total target function is obtained by taking the minimum of the weighted sum of each function in the multi-target function as a target.
[0014] In a possible implementation, the constraint condition includes a frequency stability constraint, a node voltage constraint, a line thermal stability constraint, and a system oscillation mode influence constraint.
[0015] In a possible implementation, the total target function is obtained based on the weight coefficient corresponding to each function, by taking the minimum of the weighted sum of each function in the multi-target function as a target, and includes:
[0016] The total target function is determined according to the expression:
[0017] In the formula, F(x) represents the total target function, f1 represents a first function corresponding to line load in the multi-target function, f2 represents a second function corresponding to system loss in the multi-target function, f3 represents a third function corresponding to the installation cost of the shunt transformer in the multi-target function, w1 represents a weight coefficient corresponding to the first function, w2 represents a weight coefficient corresponding to the second function, w3 represents a weight coefficient corresponding to the third function, S i represents actual power of the ith line, S i,max represents rated capacity of the ith line, R i represents line resistance of the ith line, I i represents line current of the ith line, C pst represents the cost of installing the shunt transformer, A x represents a set of installation positions of the shunt transformer, |A x represents the total number of shunt transformer installation positions in the set of installation positions, P X represents the expected loss value, C X represents the installation budget value, (P X +C X 1 in +1) represents the rated value, and M represents the total number of lines in the target power area.
[0018] In a possible implementation, the frequency stability constraint is:
[0019] Δf≤Δf max ;
[0020] In the formula, Δf represents the frequency deviation of the target power area, and Δf max represents the preset maximum frequency deviation.
[0021] In a possible implementation, the system oscillation mode influence constraint is:
[0022]
[0023] In the formula, ζ k represents the damping ratio of the kth oscillation mode, ζ min represents the preset minimum damping ratio, and modes represents the set of all oscillation modes.
[0024] In a possible implementation, the solving the total target function based on the constraint condition and the alternative installation position to obtain the optimal access position of the phase-shifting transformer of the target power area comprises:
[0025] Obtaining the load distribution and geographical information of the target power area;
[0026] Generating a preset population size of individuals according to the constraint condition, the alternative installation position, the load distribution, and the geographical information;
[0027] According to the total target function, calculating the first fitness of each individual; according to the first fitness, determining the individual optimal position of each individual in the population and the group optimal position of the population; according to the individual optimal position and the group optimal position, updating the position of each individual in the population and calculating the second fitness of each individual; according to the second fitness; selecting a plurality of individuals from the population to perform crossover and mutation to obtain updated individuals; completing the iteration of all individuals in the population once.
[0028] Continuously iterating until the maximum iteration number is reached, determining the group optimal position of the current population, and taking the group optimal position of the current population as the optimal access position of the phase-shifting transformer of the target power area.
[0029] In a possible implementation, before the power flow analysis of the target power area and the determination of the alternative installation position of the phase-shifting transformer in the target power area, the method further comprises:
[0030] Divide the planned power system to obtain at least one sub-region;
[0031] Take each sub-region as a target power region respectively;
[0032] After solving the total objective function based on the constraint condition and the alternative installation position, the optimal access position of the phase-shifting transformer in the target power region is obtained.
[0033] According to the optimal access position of the phase-shifting transformer in all sub-regions, the optimal access position of the phase-shifting transformer in the power system is obtained.
[0034] In a possible implementation, the optimal access position of the phase-shifting transformer in the power system is obtained according to the optimal access position of the phase-shifting transformer in all sub-regions, and the optimal access position of the phase-shifting transformer in the power system is obtained.
[0035] The optimal access positions of the phase-shifting transformers in all sub-regions are combined to obtain the initial access position of the phase-shifting transformer in the power system;
[0036] The initial access positions of the phase-shifting transformers adjacent to each sub-region are locally optimized to obtain the optimized access position;
[0037] The optimal access position of the phase-shifting transformer in the power system is obtained based on the optimized access position and the initial access position that is not locally optimized.
[0038] In a second aspect, an embodiment of the present application provides a phase-shifting transformer site selection device, comprising:
[0039] An analysis module is configured to perform power flow analysis on a target power region to determine alternative installation positions of a phase-shifting transformer in the target power region.
[0040] A building module is configured to build a multi-objective function with the line load balancing of the target power region, the minimum system loss of the target power region, and the minimum installation cost of the phase-shifting transformer as the target.
[0041] A determination module is configured to determine a total objective function according to a preset rated value of load balancing in a target power region, a system expected loss value of the target power region, an installation budget value of the phase-shifting transformer, and the multi-objective function, and establish a constraint condition of the total objective function.
[0042] A solving module is configured to solve the total objective function based on the constraint condition and the alternative installation position to obtain the optimal access position of the phase-shifting transformer in the target power region.
[0043] Compared with the prior art, the embodiment of the present application has the following beneficial effects:
[0044] The embodiment of the present application can determine the position where the phase-shifting transformer can be installed, i.e., the alternative installation position, by performing the power flow analysis on the target power area; a multi-objective function is established with the line load balancing, the minimum system loss and the minimum phase-shifting transformer installation cost as the target, and the total objective function is determined according to the rated value of each function in the multi-objective function, the system expected loss value and the installation budget value, so that the multi-objective function can be converted into a single objective function for fast solution, and meanwhile the weight of each function can be dynamically adjusted according to the actual situation in the target power area, so that the total objective function is more in line with the actual demand of the target power area; and the total objective function is solved through the constraint condition and the alternative installation position, so that the optimal access position of the phase-shifting transformer in the target power area can be quickly and accurately obtained. BRIEF DESCRIPTION OF DRAWINGS
[0045] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the drawings needed to be used in the embodiments or prior art description will be briefly introduced. Obviously, the drawings in the following description are only some embodiments of the present application, and other drawings can be obtained by those skilled in the art without any creative effort.
[0046] Figure 1 is the application scenario diagram of the site selection method of the phase-shifting transformer provided by the embodiment of the present application;
[0047] Figure 2 is the implementation flowchart of the site selection method of the phase-shifting transformer provided by the embodiment of the present application;
[0048] Figure 3 is the structural schematic diagram of the site selection device of the phase-shifting transformer provided by the embodiment of the present application. DETAILED DESCRIPTION
[0049] In the following description, specific details are set forth such as particular system configurations, techniques, etc., in order to provide a thorough understanding of the embodiments of the present application. However, it should be apparent to those skilled in the art that the present application can be practiced in other embodiments that depart from these specific details. In other instances, detailed descriptions of well-known systems, devices, circuits, and methods are omitted so as not to obscure the description of the present application with unnecessary detail.
[0050] In order to make the objects, technical solutions and advantages of the present application clearer, the following will be described with reference to the drawings through specific embodiments.
[0051] Figure 1 application scenario diagram of a site selection method of a phase-shifting transformer is shown, and the site selection method of the phase-shifting transformer can be applied to the distribution network of a power system, such as Figure 1The structure of the 33-node power distribution network shown, the corresponding regional nodes and lines of the power distribution network, and reasonable selection of the access position of the phase-shifting transformer can effectively control power flow and ensure the stability of the power grid.
[0052] Figure 2 The implementation flowchart of the site selection method of the phase-shifting transformer provided in the embodiment is described in detail as follows.
[0053] In step 201, power flow analysis is performed on the target power region to determine the candidate installation positions of the phase-shifting transformer in the target power region.
[0054] In this embodiment, when determining the access position of the phase-shifting transformer, power flow analysis can be performed on the target power region first, and then the lines in which the phase-shifting transformer can be accessed are selected from the lines of the target power region according to the analysis result, so as to obtain the candidate installation positions of the phase-shifting transformer. On this basis, subsequent processing is performed, the candidate installation positions are comprehensively considered, and the optimal access position of the phase-shifting transformer is selected from the candidate installation positions, so as to improve the accuracy and efficiency of site selection.
[0055] Here, the power flow analysis of the target power region is generally performed through power flow calculation, and the operating state of the target power region can be described by the node voltage method.
[0056] Suppose that the target power region contains N nodes, the current operating state of the power grid can be described by the following formula:
[0057]
[0058] In the formula, P j is the active power of the jth node, Q j is the reactive power of the jth node, |V j is the voltage amplitude of the jth node, |V s is the voltage amplitude of the sth node, θ js is the phase difference between the jth node and the sth node, θ js = θ j - θ s , θ j is the phase angle of the jth node, θ s is the phase angle of the sth node, G js is the real part of the admittance matrix of the line js formed by the jth node and the sth node, and B js is the imaginary part of the admittance matrix of the line js formed by the jth node and the sth node.
[0059] A phase-shifting transformer alters the power flow distribution on a connected line by introducing a controllable phase shift angle φ. Assuming a phase-shifting transformer is installed on a line, its function is equivalent to adjusting the total impedance and power flow direction of the target line, based on the original admittance expression. The corresponding formula is as follows:
[0060]
[0061] In the formula, I js Z represents the current in line js. js This represents the complex impedance of the line js.
[0062] By adding the φ parameter, phase-shifting transformers can flexibly change the power transmission path, thereby alleviating overload on certain lines or optimizing power flow distribution.
[0063] Optionally, based on the power flow analysis results, alternative installation locations for the phase-shifting transformer can be determined. This can be achieved by first selecting lines with load rates higher than a first preset value and lines with load rates lower than a second preset value from the target power area, based on the power flow analysis results. The first preset value is higher than the second preset value. In other words, lines with extremely high load rates (i.e., extremely heavy power flow) and extremely low load rates (i.e., extremely low power flow) are selected as alternative lines from the target power area.
[0064] Then, both ends of all the alternative lines are used as alternative installation locations for the phase-shifting transformer.
[0065] Alternative installation locations can form a set of alternative locations. For example, from a power flow section consisting of M lines, selecting p lines with extremely heavy power flow and q lines with extremely low power flow as alternative lines, the set of alternative locations can be {L}. ia |L 11 ,L 12 ,L 21 ,L 22 ,…,L n1 ,L n2}, where n = p + q and n ≤ M, L ia This indicates that the phase-shifting transformer is installed at the beginning or end of the i-th line, where a=1 indicates the beginning of the line and a=2 indicates the end of the line.
[0066] Step 202: Establish a multi-objective function with the objectives of balancing line load in the target power area, minimizing system losses in the target power area, and minimizing the installation cost of phase-shifting transformers.
[0067] In this embodiment, the consideration and optimization are carried out from three perspectives: line load, system loss, and transformer installation cost in the target power area.
[0068] The load balance in power system operation directly determines the stability of the system and the service life of the equipment. If some lines are overloaded for a long time while other lines are lightly loaded, not only will it result in unnecessary energy loss, but also will increase the probability of equipment damage. Therefore, the phasing transformer site selection needs to achieve the balance of power distribution among lines as much as possible. Then the first function with the line load balance as the target can be:
[0069]
[0070] In the formula, f1 represents the first function corresponding to the line load in the multi-objective function, S i represents the actual power of the i-th line, S i,max represents the rated capacity of the i-th line, and M represents the total number of lines in the target power area.
[0071] System loss (such as line resistance loss and transformer loss) is an important part of power production cost and one of the sources of carbon emissions. Under the same load level, the phasing transformer can significantly reduce line loss by adjusting the power flow. Then the second function with the minimum system loss as the target can be:
[0072]
[0073] In the formula, f2 represents the second function corresponding to the system loss in the multi-objective function, R i represents the line resistance of the i-th line, I i represents the line current of the i-th line.
[0074] The phasing transformer technology is complex and costly, and its economy has a major impact on the investment decisions of power companies. Therefore, when optimizing the site selection, the purchase, installation and maintenance costs need to be reduced as much as possible, and the line topology needs to be combined to avoid redundant equipment. Then the third function with the minimum installation cost of the phasing transformer as the target can be:
[0075] f3 = C pst |A x |;
[0076] In the formula, f3 represents the third function corresponding to the installation cost of the phasing transformer in the multi-objective function, C pst represents the cost of installing the phasing transformer, A x represents the installation location set of the phasing transformer, |A x represents the total number of phasing transformer installation locations in the installation location set.
[0077] In step 203, the total target function is determined according to the preset rated value of load balancing in the target power region, the system expected loss value of the target power region, the installation budget value of the phase-shifting transformer, and the multi-target function, and a constraint condition of the total target function is established.
[0078] In the related art, the multi-target function is usually added by a preset weight to obtain a single-target function, and the optimal solution of the single-target function is obtained by solving the single-target function. However, the inventor finds that the weight of the single-target function is usually determined and fixed, but the load level of each line and the power flow distribution are variable in actual power grid operation, and the power flow distribution and the load level of different power regions are also different, so the single-target function with a fixed weight cannot be applied to each power region.
[0079] In this embodiment, the weight in the single-target function is dynamically adjusted to form the total target function, so that the total target function is suitable for the target power region to be planned, and the optimal access position of the phase-shifting transformer is accurately found.
[0080] For example, when the overload risk of part of the lines in the target power region is high, the weight of the second function corresponding to the system loss can be increased, and the weight of the third function corresponding to the installation cost of the phase-shifting transformer can be reduced.
[0081] In addition, in actual operation, the priority of each function in the total target function may change with time and operating state. For example, load balancing may be the main target during a high-load period, and economy may be more important during a low-load period. The target power region can be predicted by using a machine learning model to dynamically capture the load variation trend and the power flow distribution characteristics, so as to dynamically determine the change of the weight in the total target function.
[0082] In this embodiment, the rated value of each function is preset, and the offset degree of each function is determined by using the value of each function and the rated value corresponding to the function, so as to dynamically adjust the weight in the total target function.
[0083] Here, the preset rated value of load balancing in the target power region, that is, the rated value of the first function, can be set to 1. The preset system expected loss value of the target power region, that is, the rated value of the second function. The preset installation budget value of the phase-shifting transformer, that is, the rated value of the third function.
[0084] Optionally, the total target function is determined according to the preset rated value of load balancing in the target power area, the system expected loss value of the target power area, the installation budget value of the phase-shifting transformer, and the multi-objective function. The total target function can be determined according to the rated value, the system expected loss value, the installation budget value, and the multi-objective function, and then the weight coefficients corresponding to each function in the multi-objective function are determined. Then, based on the weight coefficients corresponding to each function, the total target function is obtained by minimizing the weighted sum of each function in the multi-objective function.
[0085] The expression of the total target function can be:
[0086] minF(x)=w1f1+w2f2+w3f3;
[0087] In the formula, F(x) represents the total target function, f1 represents the first function corresponding to the line load in the multi-objective function, f2 represents the second function corresponding to the system loss in the multi-objective function, f3 represents the third function corresponding to the installation cost of the phase-shifting transformer in the multi-objective function, w1 represents the weight coefficient corresponding to the first function, w2 represents the weight coefficient corresponding to the second function, and w3 represents the weight coefficient corresponding to the third function.
[0088] The weight coefficient corresponding to the first function can be:
[0089]
[0090] The weight coefficient corresponding to the second function can be:
[0091]
[0092] The weight coefficient corresponding to the third function can be:
[0093]
[0094] In the formula, P X represents the expected loss value, C X represents the installation budget value, (P X +C X +1) represents the rated value, and M represents the total number of lines in the target power area.
[0095] It should be noted that in actual solving, the execution mode of steps 202 and 203 is not limited, and steps 202 and 203 can be executed simultaneously, that is, the total target function and the constraint condition of the total target function can be directly established. Alternatively, steps 202 and 203 can be executed in steps, that is, step 202 is executed first, and then step 203 is executed.
[0096] In step 204, the total target function is solved based on the constraint condition and the alternative installation position to obtain the optimal access position of the phase-shifting transformer in the target power area.
[0097] In the embodiment, the alternative installation positions can be taken as a solution space, and the optimal solution, i.e., the optimal access position of the phase-shifting transformer of the target power region, can be obtained by solving a total objective function through a constraint condition.
[0098] The embodiment of the application can determine the positions where the phase-shifting transformer can be installed, i.e., the alternative installation positions, through power flow analysis of the target power region; a multi-objective function is established with line load balancing, minimum system loss and minimum phase-shifting transformer installation cost as targets, and a total objective function is determined according to the rated values of each function in the multi-objective function, system expected loss value and installation budget value, so that the multi-objective function can be converted into a single objective function for fast solving, and meanwhile, the weights of each function can be dynamically adjusted according to the actual situation in the target power region, so that the total objective function is more in line with the actual demand of the target power region; and the total objective function is solved through the constraint condition and the alternative installation positions, so that the optimal access position of the phase-shifting transformer of the target power region can be quickly and accurately obtained.
[0099] In some embodiments, the constraint condition includes a frequency stability constraint, a node voltage constraint, a line thermal stability constraint and a system oscillation mode influence constraint.
[0100] Generally, the selection of the transformer site pays more attention to economy and energy efficiency optimization, but the inventors find that the consideration of the dynamic stability of the power grid is insufficient. Therefore, the stability-related constraint can be considered.
[0101] Optionally, a backup power grid stability index, such as a transient stability margin and a frequency stability range, can be set as the constraint condition, i.e., the frequency stability constraint can be obtained as:
[0102] Δf≤Δf max ;
[0103] In the formula, Δf represents the frequency deviation of the target power region, and Δf max represents the preset maximum frequency deviation. Exemplarily, the maximum frequency deviation can be ±0.5 Hz.
[0104] To ensure that the voltage amplitudes of all nodes are within the allowed range (such as 0.95-1.05 times the rated value), the node voltage constraint can be set, which can be specifically:
[0105]
[0106] In the formula, V j represents the node voltage of the jth node, V min represents the minimum allowed value of the node voltage, and V maxdenotes the maximum allowed value of node voltage, N denotes the total number of nodes in the target power area, i.e., the set of nodes.
[0107] To ensure that the power flow of all lines does not exceed its thermal stability limit, a line thermal stability constraint can be set, which can be specifically:
[0108]
[0109] wherein S i denotes the actual power of the i-th line, S rimax denotes the thermal stability limit of the i-th line, and M denotes the total number of lines in the target power area, i.e., the set of lines.
[0110] In this embodiment, a time-delay response simulation is also introduced to evaluate the influence of the shunt reactor site selection on the system oscillation mode, so that the stability constraint can be considered, i.e., the system oscillation mode influence constraint is:
[0111]
[0112] wherein ζ k denotes the damping ratio of the k-th oscillation mode, ζ min denotes the preset minimum damping ratio, which can be 0.03-0.1, and depends on the system stability requirement, and modes denotes the set of all oscillation modes.
[0113] wherein the damping ratio of the k-th oscillation mode can be calculated by the following formula:
[0114] ζ k = -Re(λ k )2+Im(λ k )2Re(λ k );
[0115] wherein λ k denotes the eigenvalue of the k-th oscillation mode, which can be obtained by the state matrix of the system, and the formula is λ k = Re(λ k )+jIm(λ k ); Re(λ k ) is the real part of the eigenvalue, indicating the decay speed of the oscillation mode; and Im(λ k ) is the imaginary part of the eigenvalue, indicating the oscillation frequency of the oscillation mode.
[0116] In some embodiments, based on the constraint condition and the alternative installation position, the total objective function is solved to obtain the optimal access position of the shunt reactor of the target power area, which can be:
[0117] Step 1: Obtain the load distribution and geographic information of the target power area.
[0118] Step two, generating preset population size individuals according to the constraint condition, alternative installation position, load distribution and geographic information.
[0119] In this embodiment, the initial population can be generated by the load distribution and geographic information of the target power area, so as to improve the initial quality of the solution.
[0120] Optionally, a part of the initial population can be generated by randomly generating the initial population to ensure that the solution space is fully explored, and the access position of the phase-shifting transformer representing several schemes. Another part of the individuals can be generated according to the load distribution and geographic information to improve the initial quality of the solution, so as to improve the efficiency of the solution by taking into account the range of the initial individual solution in the solution space and the initial quality of the solution.
[0121] Here, each individual can be represented as a vector containing a transformer site selection scheme when generating the individual, and each vector component represents whether a certain candidate site is built or the scale of the built site. Each individual is encoded as a vector with a length of N.
[0122] Step three, calculating the first fitness of each individual according to the total objective function; determining the individual optimal position of each individual in the population and the group optimal position of the population according to the first fitness; updating the position of each individual in the population according to the individual optimal position and the group optimal position, and calculating the second fitness of each individual; selecting multiple individuals from the population for crossover and mutation according to the second fitness to obtain updated individuals; completing the iteration of all individuals in the population once.
[0123] In this embodiment, the total objective function is used as the fitness function, which can comprehensively consider the line load of the transformer, system loss, installation cost and the like.
[0124] In the process of one iteration, the individual optimal position of each individual and the group optimal position of the population are determined by the method in the particle swarm optimization algorithm, and each individual is updated once, so as to perform global search in the solution space.
[0125] Then, multiple individuals can be selected for crossover and mutation by the method in the genetic algorithm, and the individuals in the population are updated again to jump out of the local optimal condition.
[0126] Before the selection, crossover and mutation operations are performed, the second fitness of each individual can be calculated, and the parameters of the genetic operation can be determined according to the distribution of the second fitness in the population. The parameters of the genetic operation can include the number of selected individuals, the method of crossover, the probability of crossover and the probability of mutation, so as to improve the diversity of the population.
[0127] For example, when the fitness concentration is high and stagnation occurs, the parameters of the genetic operation can be adjusted to increase the weight of the genetic operation; otherwise, the intervention of global search by the particle swarm can be used.
[0128] Here, the selection operation can select the superior individuals into the next generation according to the non-inferior solution ranking and the crowding distance.
[0129] Step four, iterate until the maximum number of iterations is reached, determine the population optimal position of the current population, and take the population optimal position of the current population as the optimal access position of the phase-shifting transformer in the target power region.
[0130] In this embodiment, the finally determined population optimal position is the optimal solution of the total objective function, so that the optimal access position of the phase-shifting transformer in the target power region can be obtained.
[0131] In some embodiments, before performing the power flow analysis on the target power region and determining the candidate installation positions of the phase-shifting transformer in the target power region, the power system to be planned can be divided into at least one sub-region first; and each sub-region is taken as the target power region respectively.
[0132] Correspondingly, after solving the total objective function based on the constraint conditions and the candidate installation positions to obtain the optimal access position of the phase-shifting transformer in the target power region, the optimal access position of the phase-shifting transformer in the power system can be obtained according to the optimal access positions of the phase-shifting transformers in all sub-regions.
[0133] Since the large power grid system is large and complex, there are many candidate site selection positions of the phase-shifting transformer, and it is difficult to directly optimize the entire power grid system as a target power region, which is low in efficiency and easy to fall into a local optimal solution. Therefore, the entire power system can be divided into multiple sub-regions, the total objective function is established for each sub-region, the site selection of the phase-shifting transformer is performed, and then the site selection results of each region are combined to obtain the optimal access position of the phase-shifting transformer in the entire power system.
[0134] Here, after dividing the entire power system into multiple sub-regions, the power flow analysis can be performed on each sub-region to determine the candidate installation positions of the phase-shifting transformer in each sub-region. The power flow analysis can also be performed on the entire power system to determine the candidate installation positions in the power system, and then the candidate installation positions in each sub-region can be obtained according to the division of each sub-region.
[0135] Optionally, according to the optimal access positions of the phase-shifting transformers in all sub-regions, the optimal access positions of the phase-shifting transformers in all sub-regions are combined to obtain initial access positions of the phase-shifting transformers in the power system; the initial access positions adjacent to each sub-region are locally optimized to obtain optimized access positions; and based on the optimized access positions and the initial access positions that are not locally optimized, the optimal access positions of the phase-shifting transformers in the power system are obtained.
[0136] In the embodiment, since the power system is divided into multiple sub-regions, the optimization solving is performed for each sub-region, which may cause conflicts in the access positions of the phase-shifting transformers at positions adjacent to each sub-region. Therefore, the regions with potential conflicts can be locally optimized to obtain the optimized access positions of the phase-shifting transformers.
[0137] Here, the initial access positions that are not locally optimized refer to the initial access positions of the regions without potential conflicts, i.e., the initial access positions that do not need to be locally optimized.
[0138] The embodiment of the application can determine the positions where the phase-shifting transformers can be installed, i.e., the alternative installation positions, by performing the power flow analysis on the target power region; a multi-objective function is established with the line load balancing, the minimum system loss and the minimum installation cost of the phase-shifting transformers as the targets, and a total objective function is determined according to the rated values of each function in the multi-objective function, the system expected loss value and the installation budget value, so that the multi-objective function can be converted into a single objective function for fast solving, and the weights of each function can be dynamically adjusted according to the actual situation in the target power region, so that the total objective function is more in line with the actual needs of the target power region; and the total objective function is solved through the constraint conditions and the alternative installation positions, so that the optimal access positions of the phase-shifting transformers in the target power region can be quickly and accurately obtained. The particle swarm optimization algorithm and the genetic algorithm are combined to perform global search in the solution space and jump out of the local optimum in time when falling into the local optimum, which can improve the efficiency of the optimization solving and accurately obtain the optimal access positions of the phase-shifting full-bridge transformers. When the power system is complex and large, the power system can be divided, the total objective function is established for each sub-region, and the optimization solving is performed, so that the total objective function can be matched with the corresponding sub-region; and the optimal access positions of each sub-region are combined to obtain the optimal access positions of the entire power system, which can improve the accuracy and efficiency of the phase-shifting transformer site selection.
[0139] It should be understood that the size of the serial number of each step in the above embodiment does not mean the execution order, and the execution order of each process should be determined according to its function and inherent logic, and should not constitute any limitation on the implementation process of the embodiment of the application.
[0140] The following is an embodiment of the device of the present application, for details not described in detail, can refer to the corresponding method embodiment described above.
[0141] Figure 3 The structure diagram of the site selection device of the phase-shifting transformer provided by the embodiment of the present application is shown, for the convenience of description, only the part related to the embodiment of the present application is shown, and the details are as follows:
[0142] As Figure 3 shown, the site selection device 30 of the phase-shifting transformer comprises:
[0143] The analysis module 31 is configured to perform power flow analysis on the target power area, and determine the candidate installation position of the phase-shifting transformer in the target power area.
[0144] The establishment module 32 is configured to establish a multi-objective function with the line load balancing of the target power area, the minimum system loss of the target power area, and the minimum installation cost of the phase-shifting transformer as the target.
[0145] The determination module 33 is configured to determine a total objective function according to a preset rated value of the load balancing in the target power area, a system expected loss value of the target power area, an installation budget value of the phase-shifting transformer, and the multi-objective function, and establish a constraint condition of the total objective function.
[0146] The solving module 34 is configured to solve the total objective function based on the constraint condition and the candidate installation position, and obtain the optimal access position of the phase-shifting transformer in the target power area.
[0147] In a possible implementation, the determination module 33 is specifically configured to:
[0148] According to the rated value, the system expected loss value, the installation budget value, and the multi-objective function, determine the weight coefficient corresponding to each function in the multi-objective function.
[0149] Based on the weight coefficient corresponding to each function, the total objective function is obtained with the minimum weighted sum of each function in the multi-objective function as the target.
[0150] In a possible implementation, the constraint condition comprises a frequency stability constraint, a node voltage constraint, a line thermal stability constraint, and a system oscillation mode influence constraint.
[0151] In a possible implementation, the determination module 33 is specifically configured to:
[0152] According to the expression: determine the total objective function;
[0153] In the formula, F(x) represents a total target function, f1 represents a first function corresponding to line load in the multi-objective function, f2 represents a second function corresponding to system loss in the multi-objective function, f3 represents a third function corresponding to installation cost of phase-shifting transformer in the multi-objective function, w1 represents a weight coefficient corresponding to the first function, w2 represents a weight coefficient corresponding to the second function, w3 represents a weight coefficient corresponding to the third function, S i represents actual power of the i-th line, S i,max represents rated capacity of the i-th line, R i represents line resistance of the i-th line, I i represents line current of the i-th line, C pst represents installation cost of the phase-shifting transformer, A x represents a set of installation positions of the phase-shifting transformer, |A x represents total number of installation positions of the phase-shifting transformer in the set of installation positions, P X represents expected loss value, C X represents installation budget value, (P X +C X +1) in which 1 represents a rated value, and M represents total number of lines in the target power area.
[0154] In a possible implementation, the frequency stability constraint is:
[0155] Δf≤Δf max ;
[0156] In the formula, Δf represents frequency deviation of the target power area, and Δf max represents preset maximum frequency deviation.
[0157] In a possible implementation, the system oscillation mode influence constraint is:
[0158]
[0159] In the formula, ζ k represents damping ratio of the k-th oscillation mode, ζ min represents preset minimum damping ratio, and modes represents a set of all oscillation modes.
[0160] In a possible implementation, the solving module 34 is specifically configured to:
[0161] obtain load distribution and geographical information of the target power area;
[0162] generate preset population size of individuals according to the constraint condition, the alternative installation position, the load distribution and the geographical information;
[0163] According to the total objective function, a first fitness of each individual is calculated; according to the first fitness, an individual optimal position of each individual in the population and a group optimal position of the population are determined; according to the individual optimal position and the group optimal position, a position of each individual in the population is updated, and a second fitness of each individual is calculated; according to the second fitness; a plurality of individuals in the population are selected for crossover and mutation to obtain updated individuals; one iteration of all individuals in the population is completed;
[0164] The iteration is continuously performed until a maximum iteration number is reached, a group optimal position of a current population is determined, and the group optimal position of the current population is taken as an optimal access position of the phase-shifting transformer of the target power region.
[0165] In a possible implementation, the analysis module 31 is further configured to:
[0166] The power system to be planned is divided to obtain at least one sub-region;
[0167] Each sub-region is taken as a target power region respectively;
[0168] The solving module 34 is further configured to:
[0169] The optimal access positions of the phase-shifting transformers in the power system are obtained according to the optimal access positions of the phase-shifting transformers of all sub-regions.
[0170] In a possible implementation, the solving module 34 is specifically configured to:
[0171] The optimal access positions of the phase-shifting transformers of all sub-regions are combined to obtain initial access positions of the phase-shifting transformers in the power system;
[0172] The initial access positions adjacent to each sub-region are locally optimized to obtain optimized access positions;
[0173] The optimal access positions of the phase-shifting transformers in the power system are obtained based on the optimized access positions and the initial access positions that are not locally optimized.
[0174] In the above embodiments, the description of each embodiment has its own focus, and the parts not described or recorded in a certain embodiment can be referred to the related description of other embodiments.
[0175] Those skilled in the art can appreciate that the templates, units and algorithm steps of each example described in combination with the embodiments disclosed herein can be implemented in electronic hardware or a combination of computer software and electronic hardware. Whether the functions are implemented in hardware or software depends on the specific application and design constraints of the technical solution. The skilled person can use different methods to implement the described functions for each specific application, but such implementation should not be considered beyond the scope of the present application.
[0176] If the modules / units are implemented in the form of software function units and sold or used as independent products, they can be stored in a computer readable storage medium. Based on this understanding, all or part of the processes in the above-mentioned embodiment methods can also be completed by instructing related hardware through a computer program, and the computer program can be stored in a computer readable storage medium. When the processor executes the computer program, the steps of each method embodiment described above can be implemented. The computer program includes computer program code, which can be in the form of source code, object code, executable files or some intermediate forms, etc. The computer readable medium can include any entity or device capable of carrying computer program code, recording medium, U disk, mobile hard disk, magnetic disk, optical disk, computer memory, read-only memory, random access memory, electrical carrier signal, telecommunication signal and software distribution medium, etc.
[0177] The above embodiments are only used to illustrate the technical solutions of the present application, but not limit it; although the present application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that the technical solutions recorded in the foregoing embodiments can be modified, or some technical features can be replaced by equivalents; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the spirit and scope of the technical solutions of the embodiments of the present application, and should be included in the protection scope of the present application.
Claims
1. A method for selecting the location of a phase-shifting transformer, characterized in that, include: Perform power flow analysis on the target power area to determine alternative installation locations for the phase-shifting transformer within the target power area; A multi-objective function is established with the objectives of balancing line load in the target power area, minimizing system losses in the target power area, and minimizing the installation cost of phase-shifting transformers in the target power area. The overall objective function is determined based on the preset load balancing rating within the target power area, the expected system loss value of the target power area, the installation budget value of the phase-shifting transformer, and the multi-objective function. Establish the constraints for the overall objective function; Based on the constraints and the alternative installation locations, the overall objective function is solved to obtain the optimal connection location of the phase-shifting transformer in the target power area.
2. The method for selecting the location of a phase-shifting transformer according to claim 1, characterized in that, The step of determining the overall objective function based on the preset load balancing rating within the target power area, the expected system loss value of the target power area, the installation budget value of the phase-shifting transformer, and the multi-objective function includes: Based on the rated value, the expected system loss value, the installation budget value, and the multi-objective function, determine the weight coefficients corresponding to each function in the multi-objective function; Based on the weight coefficients corresponding to each function, the overall objective function is obtained by minimizing the weighted sum of each function in the multi-objective function.
3. The method for selecting the location of a phase-shifting transformer according to claim 1, characterized in that, The constraints include frequency stability constraints, node voltage constraints, line thermal stability constraints, and system oscillation mode influence constraints.
4. The method for selecting the location of a phase-shifting transformer according to claim 2, characterized in that, The overall objective function, derived by minimizing the weighted sum of all functions in the multi-objective function based on the weight coefficients corresponding to each function, includes: According to the expression: Determine the overall objective function; In the formula, F(x) represents the overall objective function, f1 represents the first function corresponding to the line load in the multi-objective function, f2 represents the second function corresponding to the system loss in the multi-objective function, f3 represents the third function corresponding to the phase-shifting transformer installation cost in the multi-objective function, w1 represents the weighting coefficient corresponding to the first function, w2 represents the weighting coefficient corresponding to the second function, w3 represents the weighting coefficient corresponding to the third function, and S i S represents the actual power of the i-th line. i,max R represents the rated capacity of the i-th line. i I represents the line resistance of the i-th line. i C represents the line current of the i-th line. pst A represents the cost of installing a phase-shifting transformer. x Represents the set of installation locations for phase-shifting transformers, |A x | represents the total number of phase-shifting transformer installation locations in the set of installation locations, P X C represents the expected loss value. X This represents the installation budget value, (P) X +C X In +1), 1 represents the rated value, and M represents the total number of lines within the target power area.
5. The method for selecting the location of a phase-shifting transformer according to claim 3, characterized in that, The frequency stability constraint is: Δf≤Δf max ; In the formula, Δf represents the frequency deviation of the target power area. max This indicates the preset maximum frequency deviation.
6. The method for selecting the location of a phase-shifting transformer according to claim 3, characterized in that, The system oscillation mode influence constraint is: In the formula, ζ k ζ represents the damping ratio of the k-th oscillation mode. min This represents the preset minimum damping ratio, and modes represents the set of all oscillation modes.
7. The method for selecting the location of a phase-shifting transformer according to any one of claims 1 to 6, characterized in that, The process of solving the overall objective function based on the constraints and alternative installation locations to obtain the optimal connection location of the phase-shifting transformer in the target power area includes: Obtain the load distribution and geographical information of the target power area; Based on the constraints, the alternative installation locations, the load distribution, and the geographical information, individuals of a preset population size are generated; Based on the overall objective function, calculate the first fitness of each individual; based on the first fitness, determine the individual optimal position of each individual in the population and the population optimal position; based on the individual optimal position and the population optimal position, update the position of each individual in the population and calculate the second fitness of each individual; based on the second fitness, select multiple individuals from the population for crossover and mutation to obtain updated individuals; complete one iteration of all individuals in the population. The process is iterated until the maximum number of iterations is reached, to determine the optimal position of the current population, and this optimal position is used as the optimal connection position of the phase-shifting transformer in the target power area.
8. The method for selecting the location of a phase-shifting transformer according to any one of claims 1 to 6, characterized in that, Before performing power flow analysis on the target power area to determine alternative installation locations for the phase-shifting transformer within the target power area, the method further includes: The planned power system is divided into at least one sub-region; Each sub-region is designated as the target power region. After solving the overall objective function based on the constraints and the alternative installation locations to obtain the optimal connection location of the phase-shifting transformer in the target power area, the method further includes: The optimal connection location of the phase-shifting transformer within the power system is obtained based on the optimal connection location of the phase-shifting transformer in all sub-regions.
9. The method for selecting the location of a phase-shifting transformer according to claim 8, characterized in that, The step of obtaining the optimal connection location of the phase-shifting transformer within the power system based on the optimal connection locations of the phase-shifting transformers in all sub-regions includes: The optimal connection locations of phase-shifting transformers in all sub-regions are merged to obtain the initial connection locations of phase-shifting transformers within the power system. The initial access positions at adjacent locations in each sub-region are locally optimized to obtain the optimized access positions. Based on the optimized access location and the initial access location without local optimization, the optimal access location of the phase-shifting transformer in the power system is obtained.
10. A site selection device for a phase-shifting transformer, characterized in that, include: The analysis module is used to perform power flow analysis on the target power area and determine the alternative installation locations of the phase-shifting transformer in the target power area; A module is established to create a multi-objective function with the objectives of balancing line load in the target power area, minimizing system losses in the target power area, and minimizing the installation cost of phase-shifting transformers in the target power area. The determination module is used to determine the overall objective function based on the preset rated value of load balancing in the target power area, the expected system loss value of the target power area, the installation budget value of the phase-shifting transformer, and the multi-objective function; And, establish the constraints for the overall objective function; The solution module is used to solve the overall objective function based on the constraints and the alternative installation locations to obtain the optimal connection location of the phase-shifting transformer in the target power area.