CN116154874B - Coordination control and optimal configuration method for multiple series devices in power distribution network - Google Patents
Coordination control and optimal configuration method for multiple series devices in power distribution network Download PDFInfo
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Abstract
The invention provides a coordination control and optimal configuration method of a plurality of series devices in a power distribution network, which comprises the following steps: establishing a power distribution network comprising loads and buses, and enabling each bus in the power distribution network to be provided with a DVR; acquiring the output power of the DVR on each bus and the voltage drop of each circuit according to the DVR simplification model; establishing an optimization model of the power distribution network, and determining input parameters, objective functions and constraint conditions of the optimization model of the power distribution network; and optimizing the input parameters of the optimization model of the DVR by adopting a simplex method and a firefly algorithm based on the improved generation, so as to obtain the optimal input parameters and minimize the capacity of all the DVRs in the power distribution network. According to the scheme, the capacity of the DVR is minimized through reasonable configuration, a corresponding optimization model is established, and an objective function and constraint conditions are established to achieve an optimal effect through an optimization algorithm.
Description
Technical Field
The invention relates to the technical field of voltage sag management equipment, in particular to a coordination control and optimal configuration method for a plurality of series equipment in a power distribution network.
Background
With the rapid development of national economy, the types and the number of the power equipment at the user side are continuously increased, the probability of occurrence of voltage drop, fluctuation flicker and other events at the power grid side is gradually increased, so that a plurality of sensitive electrical equipment cannot work normally, and huge economic loss is caused to the user side. The most significant causes of end-user power quality problems are voltage drops and short breaks, most pronounced with voltage drops. IEEE defines the voltage sag as the root mean square value of the voltage of a certain connection point in a power supply system, suddenly drops to 0.1-0.9 times rated voltage, and resumes normal short-time disturbance phenomenon after lasting 0.5 cycle to 1 minute, and events such as short circuit fault, lightning stroke, switch operation, transformer or capacitor switching, high-power induction motor and the like in a circuit are likely to cause the voltage sag. The voltage sag can cause equipment shutdown, production interruption, even personal injury and death, and huge economic loss and safety risks are caused for power users.
Dynamic voltage restorer DVR (Dynamic Voltage Restorer) is one of the effective means of managing voltage sag. The treatment effect depends on the installation position and the capacity of the DVR, and the unordered installation cannot achieve the expected treatment effect and brings great maintenance workload. The Chinese patent application of CN112039082A discloses an optimal configuration method and system for power distribution network voltage regulating equipment based on minimum loss, wherein the scheme is based on the goal of minimum loss, the voltage regulating equipment is selected according to apparent capacity, node loss change values of nodes with unqualified voltages are obtained, and the voltage is regulated to rated voltage until the voltages of all nodes are qualified. However, this solution is to select the DVR based on the goal of minimum loss, not minimum capacity, and when the load has multiple buses and has various voltage requirements, it is not necessarily applicable, and it is easy to cause the capacity waste of the DVR device, and still increases the resources consumed by the DVR. Therefore, it is necessary to optimize the power distribution network for the case of using multiple DVR devices for the power distribution network based on the topology of the power distribution network and the capacities of the DVR devices.
Disclosure of Invention
In view of the above, the invention provides a coordinated control and optimal configuration method of a plurality of series devices in a power distribution network, wherein the capacity of a DVR (digital video recorder) aiming at power grid requirements is used as an optimal target.
The technical scheme of the invention is realized as follows: the invention provides a coordination control and optimal configuration method of a plurality of series devices in a power distribution network, which comprises the following steps:
build inclusionPersonal load +.>A power distribution network with bus bars, wherein each bus bar in the power distribution network is provided with a DVR;
acquiring the output power of the DVR on each bus and the voltage drop of each circuit according to the DVR simplification model;
establishing an optimization model of the power distribution network, and determining input parameters, objective functions and constraint conditions of the optimization model of the power distribution network;
and optimizing the input parameters of the optimization model of the DVR by adopting a simplex method and a firefly algorithm based on the improved generation, so as to obtain the optimal input parameters and minimize the capacity of all the DVRs in the power distribution network.
On the basis of the above technical solution, preferably, the establishing includesPersonal load +.>The distribution network of the bus is configured with->An independent bus is used for dividing a line between a power supply and the bus and between adjacent buses, wherein the total number of the lines is +.>A load and a DVR are disposed on each line.
Preferably, the obtaining the output power of the DVR on each bus and the voltage drop of each line according to the DVR simplification model is equivalent to the DVR as a controlled voltage source with the same phase as the grid voltage and the amplitude as the difference between the expected value of the load voltage and the grid voltage.
Preferably, the establishing of the optimization model of the power distribution network is to obtain values of equivalent resistance and reactance, load power, power grid voltage rated value, power factor and maximum drop ratio on each bus respectively, and take the values of equivalent resistance and reactance, load power, power grid voltage rated value, power factor and maximum drop ratio on each bus as input parameters of the optimization model of the power distribution network of the DVR; let the same phase compensation voltage of DVR on each bus beWherein->The method comprises the steps of carrying out a first treatment on the surface of the Let the current flowing through each DVR be +.>The method comprises the steps of carrying out a first treatment on the surface of the The compensation capacity for each DVR in the distribution network is +.>The objective function is the minimum total capacity of all DVRs in the distribution network +.>。
Preferably, constraint conditions of the optimization model of the power distribution network respectively comprise load constraint, bus voltage constraint and loop constraint; wherein:
the load constraint is to includePersonal load and->Distribution network with bus bars, and voltage after power supply sag is +.>The same phase of the same phase compensation voltage as DVR, the voltage after power supply sudden rising is +.>In contrast to the phase of the in-phase compensation voltage of DVR, only amplitude compensation is performed so that each load is +.>Is>Maintained in the working voltage range, i.e.Wherein->,/>,/>For load->Lower limit of the operating voltage of>For load->Upper limit of the operating voltage of>For the grid-side residual voltage after the occurrence of a voltage sag, +.>To compensate the voltage;
bus voltage constraint is that for a power distribution network, the requirements are satisfied,/>Wherein->Is bus bar->Voltage on>;/>Is the voltage on the bus of the upper stage; />Is bus bar->The lower voltage limit is the maximum lower limit of the working voltage of all loads on the bus; />Is the upper limit of the bus voltage, is the bus +.>The upper limit of the working voltage of all the loads is minimum; />Is bus bar->And->A voltage difference therebetween;
each line meets KVL and KCL, the current of each line flows to the load on the current line and the next bus, and the voltage vectors of all lines of the power distribution network meet the following relations:。
preferably, the optimization of the input parameters of the optimization model of the DVR by adopting the improved simplex method and firefly algorithm comprises the following steps:
the first step: setting and initializing parameters of a firefly algorithm, including firefly numberStep size factor->Random step factor->Medium absorption factor->Attraction factor->And maximum number of iterationsN;
And a second step of: random initializationSpatial location of firefliesS,/>The method comprises the steps of carrying out a first treatment on the surface of the The magnitude of the attraction degree of fireflies is in direct proportion to the magnitude of the brightness, and the brightness is determined by an objective function; to make firefly at space positionSThe relation of the brightness of (2) and its objective function is +.>,/>Is an objective function; the respective target values are recalculated as the maximum luminance of firefly +.>;
And a third step of: calculating the relative brightness between firefliesAccording to the relative brightness->Determining the movement direction of fireflies;
fourth step: updating the position of the firefly, and randomly disturbing the firefly at the best position;
fifth step: updating fireflies at non-optimal positions according to a simplex method, and recalculating brightness of the fireflies after the position updating;
sixth step: judgingtIf the moment meets the ending condition, jumping to a seventh step; otherwise att+1Jumping to the third step at the moment to search for the next time;
seventh step: and outputting the optimal position and the optimal solution.
Preferably, the fourth step updates the position of the firefly, randomly perturbing the firefly at the best position to obtain the maximum brightness of each fireflyCalculating the relative brightness of firefly +.>The calculation formula of the relative brightness isWherein->For the brightness of firefly with respect to its Euclidean distance of 0, +.>Is the bottom of natural logarithm, marked by +.>Is two different fireflieshAnd (3) withjEuropean distance between->The method comprises the steps of carrying out a first treatment on the surface of the Behavior of firefly:wherein->And->Fireflies respectivelyhAnd (3) withjIs provided with a plurality of spatial positions,is fireflyhUpdated position after random perturbation, +.>As an attractive factor->Is fireflyhIn spatial position->Relative brightness of>Is fireflyjThe relative brightness at the spatial location(s),randis interval [0,1 ]]Obeys a random factor of both and distribution.
Preferably, the fifth step of updating the firefly at the non-optimal position according to the simplex method, and recalculating the brightness of the firefly after the position update, comprises the steps of: let the initial vertex beThe number of vertices is->=8, the objective function value of all initial points is calculated, the barycenter of simplex is +.>The method comprises the steps of carrying out a first treatment on the surface of the Calculating objective function values of all search points to find out optimal pointW1Selecting secondary advantagesW2,/>,/>,tFor scaling factor, let the corresponding objective function valuef(W1)Andf(W2)the method comprises the steps of carrying out a first treatment on the surface of the Make the best pointW1Sum and secondary advantagesW2Is at the center position ofW4,W4=(W1+W2)/2The method comprises the steps of carrying out a first treatment on the surface of the And randomly finding out a plurality of non-optimal firefly positions and non-suboptimal firefly positions, taking one of the positions asW3The objective function value is recorded asf (W3)For a pair ofW3Performing a reflection operation to obtain a reflection pointW5,W5=W4+μ(W4-W3),μIs the reflection coefficient; if the objective function value of the reflection pointf(W5)>f(W1)Indicating that the reflection direction is correct, and continuing to perform the expansion operation to obtain an expansion pointW6,W6=W4+λ(W5- W4),λIs the expansion coefficient; objective function value of expansion pointf(W6)>f(W1)Then use the expansion pointW6Substitution ofW3If the objective function value of the expansion pointf(W6)<f(W1)Then use the reflection pointW5Substitution ofW3The method comprises the steps of carrying out a first treatment on the surface of the If the objective function value of the reflection pointf(W5)<f (W3)Indicating the reflection direction is poor, and performing compression operation to obtain compression pointsW7,W7=W4+ρ(W3-W4),ρIs the compression coefficient; objective function value of compression pointf(W7)>f(W3)Then use the compression pointW7Instead ofW3The method comprises the steps of carrying out a first treatment on the surface of the If it isf(W3)<Objective function value of reflection pointf(W5)<f(W1)Performing a contraction operation to obtain a contraction pointW8,W8=W4-τ(W3-W4),τIs the coefficient of contraction; objective function value of contraction pointf(W8)>f(W3)Then use the contraction pointW8Substitution ofW3Otherwise using reflection pointsW5Substitution ofW3The method comprises the steps of carrying out a first treatment on the surface of the When the simplex shape is no longer changed, the brightness of each firefly is again calculated.
Preferably, the reflection coefficientμThe value of (2) is 1; coefficient of expansionλThe value of (2); compression coefficientρThe value of (2) is 0.5; coefficient of contractionτThe value of (2) is 0.5.
Compared with the prior art, the coordination control and optimal configuration method for the plurality of series devices in the power distribution network has the following beneficial effects:
according to the scheme, the minimum total capacity of the DVR is defined as an optimization target, a corresponding objective function and optimization conditions are set, and an optimal solution is searched through iteration, so that the capacity waste phenomenon of the DVR is reduced;
the firefly algorithm has the defects of low convergence rate and easiness in sinking into a local optimal solution, the local search speed is improved through an improved simplex method, and the characteristic of globally searching for the optimal point by combining with the firefly algorithm is avoided sinking into the local optimal solution, so that the optimization precision and accuracy are improved.
Drawings
In order to more clearly illustrate the embodiments of the invention or the technical solutions in the prior art, the drawings that are required in the embodiments or the description of the prior art will be briefly described, it being obvious that the drawings in the following description are only some embodiments of the invention, and that other drawings may be obtained according to these drawings without inventive effort for a person skilled in the art.
FIG. 1 is a schematic diagram of a power distribution network with a method for coordinated control and optimal configuration of multiple devices connected in series in the power distribution network according to the present invention;
FIG. 2 is a schematic diagram of a simplified structure of a power distribution network of a method for coordinated control and optimal configuration of multiple devices in series in the power distribution network according to the present invention;
FIG. 3 is a load voltage equation diagram of a coordination control and optimal configuration method of a plurality of series devices in a power distribution network according to the present invention;
FIG. 4 is a schematic diagram illustrating steps of a method for coordinated control and optimal configuration of multiple series devices in a power distribution network according to the present invention;
FIG. 5 is a flow chart of a single-purity method-based improved firefly algorithm for a coordinated control and optimal configuration method of multiple series devices in a power distribution network;
fig. 6 is a schematic diagram of a simplex method space search for a coordinated control and optimal configuration method of multiple series devices in a power distribution network.
Description of the embodiments
The following description of the embodiments of the present invention will clearly and fully describe the technical aspects of the embodiments of the present invention, and it is apparent that the described embodiments are only some embodiments of the present invention, not all embodiments. All other embodiments, which can be made by those skilled in the art based on the embodiments of the present invention without making any inventive effort, are intended to fall within the scope of the present invention.
As shown in fig. 1-5, the invention provides a coordination control and optimal configuration method for a plurality of series devices in a power distribution network, which comprises the following steps:
s1: and (3) establishing a power distribution network comprising loads and buses, and enabling each bus in the power distribution network to be provided with a DVR.
As shown in fig. 1 in combination with fig. 2, the build containPersonal load +.>Bus barDistribution network, is provided with->An independent bus is used for dividing a line between a power supply and the bus and between adjacent buses, wherein the total number of the lines is +.>A load and a DVR are disposed on each line. In fig. 1, it can be seen that a plurality of bus bars are arranged in series, starting from a voltage source, each line comprising a bus bar, the impedance of the bus bar, the load and the DVR. Taking line 1 as an example, the equivalent resistance of the bus is R 1 The equivalent impedance of the bus is X 1 The DVR on the line is DVR1, and the corresponding load is loadnAnd so on.
To simplify the complexity of the model, a special case is illustrated in fig. 2, in which the illustrated distribution network has only 2 loads and 2 buses, and the active power loss of the line 2 is P z2 =I 2 2 R 2 The reactive power loss of line 2 is Q z2 = I 2 2 X 2 The compensation capacity of the DVR of line 2 is,/>Active power output for DVR2, +.>Reactive power output for DVR 2; />For the compensation voltage of DRV2,I 2 is the current flowing through line 2; the compensation capacity of a DVR of a similar line 1 is +.>The method comprises the steps of carrying out a first treatment on the surface of the From the above two formulas, it can be deduced that when multiple DVRs are used, the sum of the compensation capacities of the DVRs is +.>,/>The method comprises the steps of carrying out a first treatment on the surface of the The current flowing through each DVR is。
S2: and obtaining the output power of the DVR on each bus and the voltage drop of each line according to the DVR simplified model.
As shown in fig. 3, the step S2 of obtaining the output power of the DVR on each bus and the voltage drop of each line according to the DVR simplification model is equivalent to a controlled voltage source with the same phase as the line voltage and the amplitude being the difference between the expected load voltage and the grid voltage. The DVR is generally composed of an energy storage unit, a series transformer, an inversion unit and a filtering unit. When the voltage of the power grid fluctuates, the DVR outputs the compensation voltage in an extremely short timeFor maintaining load side voltage +>And the energy storage unit is used for converting energy of the DVR in the voltage compensation process. The DVR in the scheme adopts the same-phase compensation strategy, the compensation voltage of the same-phase compensation strategy is the same as the phase of the line voltage after the sag, and is opposite to the phase of the line voltage after the sudden rise, when in actual use, only the instantaneous voltage of the line is considered, and the phase factor is not considered, so that the simplified model of the DVR is the controlled current source in the figures 1, 2 and 3.
S3: and establishing an optimization model of the power distribution network, and determining input parameters, objective functions and constraint conditions of the optimization model of the power distribution network.
The optimization model of the distribution network is built by respectively obtaining the equivalent resistance and reactance, load power, power grid voltage rated value, power factor and maximum drop ratio values of all buses, and using the equivalent resistance and reactance, load power and power grid voltage rated value of all busesThe value of the power factor and the maximum drop ratio is used as the input parameter of an optimization model of the power distribution network of the DVR; let the same phase compensation voltage of DVR on each bus beWherein->The method comprises the steps of carrying out a first treatment on the surface of the Let the current flowing through each DVR be +.>The method comprises the steps of carrying out a first treatment on the surface of the The compensation capacity for each DVR in the distribution network is +.>According to the deduction process of the above-mentioned content combining step S1, determining the objective function as the minimum total capacity of all DVRs in the distribution network。
The constraint conditions of the optimization model of the power distribution network are respectively load constraint, bus voltage constraint and loop constraint; wherein:
the load constraint is to includePersonal load and->Distribution network with bus bars, and voltage after power supply sag is +.>The same phase of the same phase compensation voltage as DVR, the voltage after power supply sudden rising is +.>In contrast to the phase of the in-phase compensation voltage of DVR, only amplitude compensation is performed so that each load is +.>Is>Maintained in the working voltage range, i.e.Wherein->,/>,/>For load->Lower limit of the operating voltage of>For load->Upper limit of the operating voltage of>For the grid-side residual voltage after the occurrence of a voltage sag, +.>To compensate for the voltage.
Bus voltage constraint is that for a power distribution network, the requirements are satisfied,/>WhereinIs bus bar->Voltage on>;/>Is the voltage on the bus of the upper stage; />Is bus bar->The lower voltage limit is the maximum lower limit of the working voltage of all loads on the bus; />Is bus bar->The upper voltage limit is the minimum upper working voltage limit of all loads on the bus; />Is bus bar->And->A voltage difference therebetween;
each line meets KVL and KCL, the current of each line flows to the load on the current line and the next bus, and the voltage vectors of all lines of the power distribution network meet the following relations:. Each line voltage meets kirchhoff voltage law, the circuit meets kirchhoff current law, one part of line current flows to a load, and the other part flows to a bus of a next-stage line. Considering that the line voltage drops under in-phase compensation, the compensated voltage of the DVR is the same as the phase of the grid voltage, and the voltage vector relationship can be simply represented as a scalar relationship.
S4: and optimizing the input parameters of the optimization model of the DVR by adopting a simplex method and a firefly algorithm based on the improved generation, so as to obtain the optimal input parameters and minimize the capacity of all the DVRs in the power distribution network.
The source of the firefly algorithm is based on the brightness of fireflies and the attraction of fireflies to other fireflies, and the higher the brightness of fireflies, the better the position of the fireflies is, and the greater the attraction of fireflies to other fireflies is. Each firefly moves and updates according to the brightness and attraction degree of the peers in the field, so that the aim of position optimization is fulfilled. In the firefly algorithm, the attraction degree of fireflies is proportional to the brightness of the fireflies, and the brightness is closely related to the objective function of the firefly algorithm. The fluorescence of fireflies is also affected by the propagation medium and absorbed partly during the transmission, so that the magnitude of the attraction is related to both the distance and the medium absorption factor.
The improved firefly algorithm based on the simplex method is adopted to optimize the input parameters of the DVR optimization model, and comprises the following steps:
the first step: setting and initializing parameters of a firefly algorithm, including firefly numberStep size factor->Random step factor->Medium absorption factor->Attraction factor->And maximum number of iterationsN。
And a second step of: random initializationSpatial location of firefliesS,/>The method comprises the steps of carrying out a first treatment on the surface of the The magnitude of the attraction degree of fireflies is in direct proportion to the magnitude of the brightness, and the brightness is determined by an objective function; to make firefly at space positionSThe relation of the brightness of (2) and its objective function is +.>,/>Is an objective function; the respective target values are recalculated as the maximum luminance of firefly +.>。
And a third step of: calculating the relative brightness between firefliesAccording to the relative brightness->The size of (2) determines the direction of movement of the firefly.
Fourth step: and updating the position of the firefly, and randomly disturbing the firefly at the best position.
The specific content of the step is that the maximum brightness of each firefly is obtainedCalculating the relative brightness of firefliesThe calculation formula of the relative brightness is +.>Wherein->For the brightness of firefly with respect to its Euclidean distance of 0, +.>Is the bottom of natural logarithm, marked by +.>Is two different fireflieshAnd (3) withjThe euclidean distance between the two,。
behavior of firefly:wherein->And->Fireflies respectivelyhAnd (3) withjSpatial position of->Is fireflyhUpdated position after random perturbation, +.>In order to attract the factors of interest,is fireflyhIn spatial position->Relative brightness of>Is fireflyjIn spatial position->Is used for the control of the relative brightness of the (c),randis interval [0,1 ]]Obeys a random factor of both and distribution. The better the spatial position of the firefly, the higher its relative brightness, and the relative brightness of the firefly is positively correlated with the objective function of its firefly algorithm.
The firefly algorithm can achieve the purpose of rapid optimization of position updating by improving the step length, and the searching process is better realized. Two different strategies for adjusting the step size may be provided depending on the current state:
(1) If firefly is a fireflyhIf the globally optimal solution is not found, a method of gradually reducing the step length is adopted, namely,/>Is fireflyhUpdating the new position after the step size, < > and>the iteration times; in each iteration, the firefly algorithm updates the position of the firefly according to the position and brightness of the firefly, adjusts the brightness of the firefly, and the iteration times are used for controlling the change amplitude and speed of the step length.
(2) If firefly is a fireflyhWhen the global optimal solution is found, a method of gradually increasing step length is adopted, namely,/>Is fireflyhUpdating the new position after the step size, < > and>is a random step size factor.
In this scheme, step length factorAnd->The value is set to 0.2, and the medium absorption factor is +.>The value is 1.
However, the firefly algorithm has the defects of low convergence speed, easy sinking into a local optimal solution and low precision. Therefore, the scheme further provides a method for globally searching the optimal solution by combining the simplex method with the firefly algorithm.
Fifth step: and updating fireflies at non-optimal positions according to a simplex method, and recalculating the brightness of the fireflies after the position updating.
The method comprises the following steps: let the initial vertex beThe number of vertices is->=8, the objective function value of all initial points is calculated, the barycenter of simplex is +.>The method comprises the steps of carrying out a first treatment on the surface of the Calculating objective function values of all search points to find out optimal pointW1Selecting secondary advantagesW2,/>,/>,tFor scaling factor, let the corresponding objective function valuef (W1)Andf(W2)the method comprises the steps of carrying out a first treatment on the surface of the Make the best pointW1Sum and secondary advantagesW2Is at the center position ofW4,W4=(W1+W2)/2The method comprises the steps of carrying out a first treatment on the surface of the And randomly finding out a plurality of non-optimal firefly positions and non-suboptimal firefly positions, taking one of the positions asW3The objective function value is recorded asf(W3)For a pair ofW3Performing a reflection operation to obtain a reflection pointW5,W5=W4+μ(W4-W3),μIs the reflection coefficient; if the objective function value of the reflection pointf (W5)>f(W1)Indicating that the reflection direction is correct, and continuing to perform the expansion operation to obtain an expansion pointW6,W6=W4+λ(W5-W4),λIs the expansion coefficient; objective function value of expansion pointf(W6)>f(W1)Then use the expansion pointW6Substitution ofW3If the objective function value of the expansion pointf(W6)<f(W1)Then use the reflection pointW5Substitution ofW3The method comprises the steps of carrying out a first treatment on the surface of the If the objective function value of the reflection pointf(W5)<f(W3)Indicating the reflection direction is poor, and performing compression operation to obtain pressurePinch pointW7,W7=W4+ρ(W3-W4),ρIs the compression coefficient; objective function value of compression pointf(W7)>f(W3)Then use the compression pointW7Instead ofW3The method comprises the steps of carrying out a first treatment on the surface of the If it isf(W3)<Objective function value of reflection pointf(W5)<f (W1)Performing a contraction operation to obtain a contraction pointW8,W8=W4-τ(W3-W4),τIs the coefficient of contraction; objective function value of contraction pointf(W8)>f(W3)Then use the contraction pointW8Substitution ofW3Otherwise using reflection pointsW5Substitution ofW3The method comprises the steps of carrying out a first treatment on the surface of the When the simplex shape is no longer changed, the brightness of each firefly is again calculated.
In this scheme, the reflection coefficientμThe value of (2) is 1; coefficient of expansionλThe value of (2); compression coefficientρThe value of (2) is 0.5; coefficient of contractionτThe value of (2) is 0.5.
The conventional simplex method is to construct a polyhedron in a space, find out the vertices of the polyhedron and compare them to find out the optimal point, secondary advantage and worst point, i.e. the above-mentionedW1、W2AndW3. Updating the worst point by reflection, compression, expansion, or the likeW3Forming a new polyhedron, wherein the reflection operation can enable the individual to search in the opposite direction, and the individual search space is enlarged; the expansion operation enables the individual to be far away from the optimal solution, and prevents the algorithm from sinking into local minimum value points; the compression and contraction operations enable the individual to more closely approximate the optimal position. The present solution therefore also improves on the simplex method. Taking three-dimensional space as an example, referring to FIG. 6, 8 points are randomly generated, corresponding to the aboveW1、W2、……、W8And introduces the concept of a center of gravity.
Sixth step: judgingtIf the moment meets the ending condition, jumping to a seventh step; otherwise att+1And jumping to the third step to search for the next time.
Seventh step: and outputting the optimal position and the optimal solution.
The foregoing description of the preferred embodiments of the invention is not intended to be limiting, but rather is intended to cover all modifications, equivalents, alternatives, and improvements that fall within the spirit and scope of the invention.
Claims (3)
1. A coordination control and optimal configuration method for a plurality of series devices in a power distribution network is characterized by comprising the following steps:
build inclusionPersonal load +.>A power distribution network with bus bars, wherein each bus bar in the power distribution network is provided with a DVR;
acquiring the output power of the DVR on each bus and the voltage drop of each circuit according to the DVR simplification model;
establishing an optimization model of the power distribution network, and determining input parameters, objective functions and constraint conditions of the optimization model of the power distribution network;
optimizing input parameters of an optimization model of the DVR by adopting a simplex method and a firefly algorithm based on an improved generation, obtaining the optimal input parameters, and minimizing the capacity of all DVRs in the power distribution network;
wherein the establishing comprisesPersonal load +.>The distribution network of the bus is configured with->An independent bus is used for dividing a line between a power supply and the bus and between adjacent buses, wherein the total number of the lines is +.>A load and a DVR are correspondingly configured on each line;
the DVR output power on each bus and the voltage drop of each line are obtained according to a DVR simplification model, and the DVR is equivalent to a controlled voltage source which has the same phase as the power grid voltage and has the amplitude of the difference between the load voltage expected value and the power grid voltage;
the method comprises the steps of establishing an optimization model of the power distribution network, namely respectively obtaining values of equivalent resistance and reactance, load power, power grid voltage rated value and power factor and maximum drop ratio on each bus, and taking the values of equivalent resistance and reactance, load power, power grid voltage rated value and power factor and maximum drop ratio on each bus as input parameters of the optimization model of the power distribution network of the DVR; let the same phase compensation voltage of DVR on each bus beWherein->The method comprises the steps of carrying out a first treatment on the surface of the Let the current flowing through each DVR be +.>The method comprises the steps of carrying out a first treatment on the surface of the The compensation capacity for each DVR in the distribution network is +.>The objective function is the minimum total capacity of all DVRs in the distribution network +.>;
Constraint conditions of the optimization model of the power distribution network respectively comprise load constraint, bus voltage constraint and loop constraint; wherein:
the load constraint is to includePersonal load and->Distribution network with bus bars, and voltage after power supply sag is +.>The same phase of the same phase compensation voltage as DVR, the voltage after power supply sudden rising is +.>In contrast to the phase of the in-phase compensation voltage of DVR, only amplitude compensation is performed so that each load is +.>Is>Maintained in the working voltage range, i.e.Wherein->,/>,/>For load->Lower limit of the operating voltage of>For load->Upper limit of the operating voltage of>In order to generate a grid-side residual voltage after a voltage sag,to compensate the voltage;
bus voltage constraint, which is to power distributionIn the case of a net, the following are satisfied,/>Wherein->Is bus bar->Voltage on>;/>Is the voltage on the bus of the upper stage; />Is bus bar->The lower voltage limit is the maximum lower limit of the working voltage of all loads on the bus; />Is bus bar->The upper voltage limit is the minimum upper working voltage limit of all loads on the bus; />Is bus bar->And->A voltage difference therebetween;
each line meets KVL and KCL, the current of each line flows to the load on the current line and the next bus, and the voltage vectors of all lines of the power distribution network meet the following relations:;
the method for optimizing the input parameters of the DVR optimization model by adopting the improved simplex method and firefly algorithm comprises the following steps:
the first step: setting and initializing parameters of a firefly algorithm, including firefly numberStep size factor->Random step factor->Medium absorption factor->Attraction factor->And maximum number of iterationsN;
And a second step of: random initializationSpatial location of firefliesS,/>The method comprises the steps of carrying out a first treatment on the surface of the The magnitude of the attraction degree of fireflies is in direct proportion to the magnitude of the brightness, and the brightness is determined by an objective function; to make firefly at space positionSThe relation of the brightness of (2) and the objective function thereof is that,/>Is an objective function; the respective target values are recalculated as the maximum luminance of firefly +.>;
And a third step of: calculating the relative brightness between firefliesAccording to the relative brightness->Determining the movement direction of fireflies;
fourth step: updating the position of the firefly, and randomly disturbing the firefly at the best position;
fifth step: updating fireflies at non-optimal positions according to a simplex method, and recalculating brightness of the fireflies after the position updating;
sixth step: judgingtIf the moment meets the ending condition, jumping to a seventh step; otherwise att+1Jumping to the third step at the moment to search for the next time;
seventh step: outputting an optimal position and an optimal solution;
the fourth step updates the position of fireflies, randomly disturbing fireflies at the best position to obtain the maximum brightness of each fireflyCalculating the relative brightness of firefly +.>The calculation formula of the relative brightness is +.>Wherein->For the brightness of firefly with respect to its Euclidean distance of 0, +.>Is the bottom of natural logarithm, marked by +.>Is two different fireflieshAnd (3) withjEuropean distance between->The method comprises the steps of carrying out a first treatment on the surface of the Behavior of firefly:wherein->And->Fireflies respectivelyhAnd (3) withjSpatial position of->Is fireflyhUpdated position after random perturbation, +.>As an attractive factor->Is fireflyhIn spatial position->Relative brightness of>Is fireflyjIn spatial position->Is used for the control of the relative brightness of the (c),randis interval [0,1 ]]A random factor obeying the uniform and distributed;
the firefly algorithm achieves the aim of quick optimization of position updating by improving the step length, and the searching process is better realized; two different strategies for adjusting the step size may be provided depending on the current state:
(1) If firefly is a fireflyhIf the globally optimal solution is not found, a method of gradually reducing the step length is adopted, namely,/>Is fireflyhUpdating the new position after the step size, < > and>the iteration times; in each iteration, updating the position of the firefly according to the position and the brightness of the firefly by a firefly algorithm, adjusting the brightness of the firefly, and controlling the change amplitude and the change speed of the step length by the iteration times;
2. The method for coordinated control and optimal configuration of a plurality of series devices in a power distribution network according to claim 1, wherein the fifth step updates the non-optimal state according to a simplex methodThe method for recalculating the brightness of the firefly with updated positions by using the firefly with good positions comprises the following steps: let the initial vertex beThe number of vertices is->=8, the objective function value of all initial points is calculated, the barycenter of simplex is +.>The method comprises the steps of carrying out a first treatment on the surface of the Calculating objective function values of all search points to find out optimal pointW1Selecting secondary advantagesW2,/>,/> tFor scaling factor, let the corresponding objective function valuef(W1)Andf(W2)the method comprises the steps of carrying out a first treatment on the surface of the Make the best pointW1Sum and secondary advantagesW2Is at the center position ofW4,W4=(W1+W2)/2The method comprises the steps of carrying out a first treatment on the surface of the And randomly finding out a plurality of non-optimal firefly positions and non-suboptimal firefly positions, taking one of the positions asW3The objective function value is recorded asf(W3)For a pair ofW3Performing a reflection operation to obtain a reflection pointW5,W5=W4+μ(W4-W3),μIs the reflection coefficient; if the objective function value of the reflection pointf (W5)>f(W1)Indicating that the reflection direction is correct, and continuing to perform the expansion operation to obtain an expansion pointW6,W6=W4+λ(W5-W4),λIs the expansion coefficient; objective function value of expansion pointf(W6)>f(W1)Then use the expansion pointW6Substitution ofW3If the objective function value of the expansion pointf(W6)<f(W1)Then use the reflection pointW5Substitution ofW3The method comprises the steps of carrying out a first treatment on the surface of the If the objective function value of the reflection pointf(W5)<f(W3)Indicating the reflection direction is poor, and performing compression operation to obtain compression pointsW7,W7=W4+ρ(W3-W4),ρIs the compression coefficient; objective function value of compression pointf(W7)>f(W3)Then use the compression pointW7Instead ofW3The method comprises the steps of carrying out a first treatment on the surface of the If it isf(W3)<Objective function value of reflection pointf(W5)<f (W1)Performing a contraction operation to obtain a contraction pointW8,W8=W4-τ(W3-W4),τIs the coefficient of contraction; objective function value of contraction pointf(W8)>f(W3)Then use the contraction pointW8Substitution ofW3Otherwise using reflection pointsW5Substitution ofW3The method comprises the steps of carrying out a first treatment on the surface of the When the simplex shape is no longer changed, the brightness of each firefly is again calculated.
3. The method for coordinated control and optimal configuration of a plurality of series devices in a power distribution network according to claim 2, wherein the reflection coefficient isμThe value of (2) is 1; coefficient of expansionλThe value of (2); compression coefficientρThe value of (2) is 0.5; coefficient of contractionτThe value of (2) is 0.5.
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