CN106972513A - A kind of line uncompensated load of Three phase four only utilizes the compensation method of capacitive element - Google Patents

Abstract

A kind of line uncompensated load of Three phase four only utilizes the compensation method of capacitive element, belongs to power quality controlling field in power system.In the case of net side system voltage is sinusoidal and symmetrical, the zero sequence of net side system, positive sequence and negative-sequence current after only being compensated with capacitive element are obtained according to symmetrical component method；Build the object function of genetic algorithm；Build the identical quantity of the population at individual number and Δ B with setting_a,ΔB_b,ΔB_c,ΔB_ab,ΔB_bc,ΔB_caBinary number that directly proportional, 6 binary numbers are linked in sequence, new, is used as the individual in primary population；Individual adaptation degree is calculated, and calculates the hereditary probability of each individual；For the individual in primary population, the size of hereditary probability and object function in the next generation is inversely proportional；Obtain making in offspring individual one group of minimum individual of target function value in step 2, record and as the optimum individual in the present age；Compare every generation optimum individual, obtain the optimal value that capacitive element compensates branch road.The present invention provides solid theoretical foundation for practical engineering application.

Description

A kind of line uncompensated load of Three phase four only utilizes the compensation method of capacitive element

Technical field

The compensation method of capacitive element is only utilized the present invention relates to a kind of line uncompensated load of Three phase four, belongs to electric power Power quality controlling field in system.

Background technology

With the development of Power Electronic Technique, high-power, Large Copacity, high degree of asymmetry load increasing, power system Load unbalanced problem is increasingly serious.The uneven stable operation to power system of threephase load, the safety of electrical equipment, and The quality of power supply causes very big negative effect.《Electricity Law of the People's Republic of China》" user power utilization must not for 32nd article of regulation Harm power supply, Electrical Safety and upset power supply, electricity consumption order.To harm power supply, Electrical Safety and upset power supply, electricity consumption order Power supply enterprise has the right to prevent ".Therefore, the capacitive element compensation method to three-phase and four-line uncompensated load is particularly important.

In current existing article, patent and practical engineering application, the compensation to uncompensated load is both needed to access perceptual nothing Work(.As reactive-load compensation element, cost, power consumption and the volume of reactor are much larger than capacitor.

The content of the invention

Present invention aims at for only being compensated using capacitive element to the uncompensated load in three-phase three-wire system Problem, proposes that a kind of line uncompensated load of Three phase four only utilizes the compensation method of capacitive element, this method utilizes symmetrical point Amount method derives zero sequence, positive sequence and negative sequence component, and constructs using negative-sequence current and reactive current as the object function of index, profit With genetic algorithm, the load unbalanced capacitive element compensation method of three-phase and four-line is constructed, heavily fortified point is provided for practical engineering application Real theoretical foundation.

Above-mentioned purpose is realized, the technical scheme that the present invention takes is as follows：

A kind of line uncompensated load of Three phase four only utilizes the compensation method of capacitive element, comprises the following steps：

Step one：In the case of net side system voltage is sinusoidal and symmetrical, U_a=U, U_b=α²U, U_c=α U, α=e^120°j, Wherein：U_a,U_b,U_cRespectively a phases, b phases and c phase voltages, U are phase voltage amplitude, and j is the imaginary part unit of plural number, and α is three-phase The voltage anglec of rotation, e be unit vector, obtained according to symmetrical component method the zero sequence of net side system after only being compensated with capacitive element, Positive sequence and negative-sequence current；

Step 2：The object function of genetic algorithm is built, object function is metIts In：Obj is object function,Zero-sequence current real part respectively under three-phase four wire system, zero sequence Electric current imaginary part, forward-order current imaginary part, negative-sequence current real part and negative-sequence current imaginary part；

Step 3：Using genetic algorithm, the numerical value of minimum capacity unit is built as base unit using in practical engineering application Quantity identical with the population at individual number of setting, with Δ B_a,ΔB_b,ΔB_c,ΔB_ab,ΔB_bc,ΔB_caIt is directly proportional, six two Binary number that system number is linked in sequence, new, is used as the individual in primary population；Wherein：ΔB_a,ΔB_b,ΔB_cFor three The susceptance value of mutually star-like compensation network, Δ B_ab,ΔB_bc,ΔB_caThe susceptance value of network is compensated for three-phase angle-style；

Step 4：Obtain after the individual in primary population, target letter is calculated using the objective function Equation in step 2 Numerical value, calculates individual adaptation degree, and calculate the hereditary probability of each individual；For the individual in primary population, in the next generation Hereditary probability and the size of object function be inversely proportional；

Step 5：Simulation gene is carried out according to the hereditary probability of the individual of each in population to intersect, restructuring and mutation process, Obtain making in offspring individual one group of minimum individual of target function value in step 2, record and as the optimum individual in the present age；

Step 6：Repeat step four, step 5 are at least 500 times, relatively per generation optimum individual, obtain whole hereditary mistake Optimum individual in journey, it is reversed according to step 3 and is changed to Δ B_a,ΔB_b,ΔB_c,ΔB_ab,ΔB_bc,ΔB_ca, that is, obtain capacitive Element compensates the optimal value of branch road；Wherein：ΔB_a,ΔB_b,ΔB_cFor the susceptance value of the star-like compensation network of three-phase, Δ B_ab,ΔB_bc, ΔB_caThe susceptance value of network is compensated for three-phase angle-style.

The present invention is relative to the beneficial effect of prior art：

1st, the present invention be directed to three-phase four wire system in uncompensated load phenomenon, and in practical engineering application inductive element into There is provided a kind of capacitive for being widely portable to three-phase four wire system member based on genetic algorithm for the problem of this is high and difficult in maintenance Part compensation method.Real part and void of the invention by calculating the forward-order current in three-phase system, negative-sequence current and zero-sequence current Portion, so as to construct the object function on negative-sequence current and reactive current, using genetic algorithm and then propose can be according to work Capacitive element minimum unit carries out the compensation method of the three-phase and four-line uncompensated load of optimal correction in Cheng Yingyong.

2nd, the line uncompensated load of a kind of Three phase four proposed by the present invention only utilizes the compensation method of capacitive element, utilizes Symmetrical component method derives zero sequence, positive sequence and negative sequence component, and constructs using negative-sequence current and reactive current as the target of index Function, using genetic algorithm, constructs the load unbalanced capacitive element compensation method of three-phase and four-line, is that practical engineering application is carried Solid theoretical foundation has been supplied, the vacancy of the capacitive element compensation method of three-phase and four-line uncompensated load has been filled up.

Brief description of the drawings

Fig. 1 is the compensation Principles of Network figure of three-phase and four-line uncompensated load.

Technical scheme is further described below in conjunction with the accompanying drawings, but is not limited thereto, it is every to this Inventive technique scheme is modified or equivalent substitution, without departing from the spirit and scope of technical solution of the present invention, all should be covered In protection scope of the present invention.

Embodiment

Embodiment one：As shown in figure 1, present embodiment discloses a kind of line uncompensated load of Three phase four only Using the compensation method of capacitive element, comprise the following steps：

Step one：In the case of net side system voltage is sinusoidal and symmetrical, U_a=U, U_b=α²U, U_c=α U, α=e^120°j, Wherein：U_a,U_b,U_cRespectively a phases, b phases and c phase voltages, U are phase voltage amplitude, and j is the imaginary part unit of plural number, and α is three-phase The voltage anglec of rotation, e be unit vector, obtained according to symmetrical component method the zero sequence of net side system after only being compensated with capacitive element, Positive sequence and negative-sequence current；

Step 2：The object function of genetic algorithm is built, object function is metIts In：Obj is object function,Zero-sequence current real part respectively under three-phase four wire system, zero sequence electricity Flow imaginary part, forward-order current imaginary part, negative-sequence current real part and negative-sequence current imaginary part；

Step 3：Using genetic algorithm, the numerical value of minimum capacity unit is built as base unit using in practical engineering application Quantity identical with the population at individual number of setting, with Δ B_a,ΔB_b,ΔB_c,ΔB_ab,ΔB_bc,ΔB_caIt is directly proportional, six two Binary number that system number is linked in sequence, new, is used as the individual in primary population；Wherein：ΔB_a,ΔB_b,ΔB_cFor three The susceptance value of mutually star-like compensation network, Δ B_ab,ΔB_bc,ΔB_caThe susceptance value of network is compensated for three-phase angle-style；

Step 4：Obtain after the individual in primary population, target letter is calculated using the objective function Equation in step 2 Numerical value, calculates individual adaptation degree, and calculate the hereditary probability of each individual；For the individual in primary population, in the next generation Hereditary probability and the size of object function be inversely proportional；

Step 5：Simulation gene is carried out according to the hereditary probability of the individual of each in population to intersect, restructuring and mutation process, Obtain making in offspring individual one group of minimum individual of target function value in step 2, record and as the optimum individual in the present age；

Step 6：Repeat step four, step 5 are at least 500 times, relatively per generation optimum individual, obtain whole hereditary mistake Optimum individual in journey, it is reversed according to step 3 and is changed to Δ B_a,ΔB_b,ΔB_c,ΔB_ab,ΔB_bc,ΔB_ca, that is, obtain capacitive Element compensates the optimal value of branch road；Wherein：ΔB_a,ΔB_b,ΔB_cFor the susceptance value of the star-like compensation network of three-phase, Δ B_ab,ΔB_bc, ΔB_caThe susceptance value of network is compensated for three-phase angle-style.

Embodiment two：Present embodiment is to further illustrating that embodiment one is made, in step one Described zero sequence, positive sequence and negative-sequence current parameter be：

Zero sequence, positive sequence and negative-sequence current parameter described in step one are：

Wherein：U is phase voltage amplitude,Respectively zero sequence, positive sequence and negative-sequence current, G_a,G_b,G_cFor three-phase star The conductance of type load, B_a,B_b,B_cFor the susceptance of the star-like load of three-phase, Δ B_a,ΔB_b,ΔB_cFor the electricity of the star-like compensation network of three-phase Receive value, Δ B_ab,ΔB_bc,ΔB_caThe susceptance value of network is compensated for three-phase angle-style, j is plural imaginary part unit.

Embodiment three：Present embodiment is further illustrating of being made to embodiment one or two, is utilized Genetic algorithm is optimized to the object function obj in step 2.

Embodiment four：Present embodiment is to further illustrating that embodiment one is made, in step 3 Described primary population at individual need to meet following condition：

1) each individual is continuous 6 binary numbers in population, and Δ B is represented respectively_a,ΔB_b,ΔB_c,ΔB_ab,ΔB_bc, ΔB_caOne group of new binary system of composition is connected, wherein；ΔB_a,ΔB_b,ΔB_cFor the susceptance value of the star-like compensation network of three-phase, Δ B_ab,ΔB_bc,ΔB_caThe susceptance value of network is compensated for three-phase angle-style；

2) value of the capacitor bank that the scope of the value of each of three binary numbers and three-phase four wire system possess Scope, i.e. 0 ＜ Δ B ＜ B_maxIt is corresponding, wherein：Δ B is any one susceptance value, B in compensation network_maxFor practical engineering application The maximum susceptance value that any one phase of middle compensation network can be compensated；

3) least unit of binary number, i.e., 1 are corresponding with the minimum unit value of three-phase four wire system capacitor bank.

Embodiment five：Present embodiment is to further illustrating that embodiment one is made, in step 4 The fitness of described primary population at individual is defined as：Wherein：Fit is fitness, and obj is the target in step 2 Function.

Embodiment 1：

As shown in figure 1, only utilizing the benefit of capacitive element this embodiment discloses herein a kind of line uncompensated load of Three phase four Compensation method, comprises the following steps：

Step one：Net side system voltage is U in the case of sinusoidal and symmetrical_a=U, U_b=α²U, U_c=α U, α=e^120°j, meter Calculate zero sequence, positive sequence and the negative-sequence current of system after only being compensated with capacitive element：

Wherein：U_a,U_b,U_cRespectively a phases, b phases and c phase voltages, U are phase voltage amplitude, and j is the imaginary part unit of plural number, α For the three-phase voltage anglec of rotation, e is unit vector,Respectively zero sequence, positive sequence and negative-sequence current, G_a,G_b,G_cFor three-phase The conductance of star-like load, B_a,B_b,B_cFor the susceptance of the star-like load of three-phase, Δ B_a,ΔB_b,ΔB_cFor the star-like compensation network of three-phase Susceptance value, Δ B_ab,ΔB_bc,ΔB_caThe susceptance value of network is compensated for three-phase angle-style；

Step 2：The object function of genetic algorithm is built, for three-phase four wire system, object function is metWherein：Obj is object function, Zero-sequence current real part respectively under three-phase four wire system, zero-sequence current imaginary part, forward-order current imaginary part, negative-sequence current real part and Negative-sequence current imaginary part；

Step 3：Build individual need in primary population, population and meet following condition：

1) each individual (represents Δ B respectively for continuous 6 binary numbers in population_a,ΔB_b,ΔB_c,ΔB_ab,ΔB_bc, ΔB_ca) the one group of new binary number constituted is connected, wherein：ΔB_a,ΔB_b,ΔB_cFor three-phase it is star-like compensation network susceptance value, ΔB_ab,ΔB_bc,ΔB_caThe susceptance value of network is compensated for three-phase angle-style；

2) 6 binary numbers, the model of the value for the capacitor bank that the scope of the value of each possesses with three-phase four wire system Enclose (i.e. 0 ＜ Δ B ＜ B_max) corresponding；Wherein：Any one susceptance value, B in Δ B compensation networks_maxFor in practical engineering application The maximum susceptance value that any one phase of compensation network can be compensated；

3) least unit (i.e. 1) of binary number is corresponding with the minimum unit value of three-phase four wire system capacitor bank；

Step 4：Formula in step one and step 2 obtains the fitness of each individual in contemporary population, fits Response is defined asAnd find out the individual value guarantor by this binary sequence and its fitness of fitness highest in the present age Deposit；Wherein：Fit is fitness, and obj is the object function in step 2；

Step 5：According to the hereditary probability of fitness value distribution of each individual of contemporary population, hereditary probability needs to meet：

1) hereditary probability is directly proportional to fitness function；

2) all individual hereditary probability sums add up to 1 in contemporary population；

Step 6：Two individuals are taken out according to each individual hereditary probability at random, in two individual binary system number sequences It is random in row to look for a same position cut-out, half section of left and right is respectively taken, new binary number sequence is constituted；With millesimal probability Its value is negated (0, which becomes 1,1, becomes 0) in a random site of new binary sequence；With the base of this two process mimic biologies Because of restructuring, mutation process, a new individual is constituted, the population at individual number identical for constituting and setting in the same way Body, is used as population of new generation；

Step 7：To population at individual repeat step four-step 6 step of a new generation, obtain every after circulating at least 500 times The data of the fitness highest individual of a generation；The fitness of successive dynasties fitness highest individual is compared, fitness is found out The binary sequence of highest individual, it, which is translated binary sequence number according to the mode that individual is built in step 3, turns into Δ B_a,ΔB_b,ΔB_c,ΔB_ab,ΔB_bc,ΔB_ca, resulting Δ B_a,ΔB_b,ΔB_c,ΔB_ab,ΔB_bc,ΔB_caAs three-phase and four-line System needs to access the susceptance value of the capacitor of each compensation branch road；Wherein：ΔB_a,ΔB_b,ΔB_cFor the star-like compensation network of three-phase Susceptance value, Δ B_ab,ΔB_bc,ΔB_caThe susceptance value of network is compensated for three-phase angle-style.

Claims (5)

1. a kind of line uncompensated load of Three phase four only utilizes the compensation method of capacitive element, it is characterised in that including following Step：

Step one：In the case of net side system voltage is sinusoidal and symmetrical, U_a=U, U_b=α²U, U_c=α U, α=e^120°j, wherein： U_a,U_b,U_cRespectively a phases, b phases and c phase voltages, U are phase voltage amplitude, and j is the imaginary part unit of plural number, and α is three-phase voltage rotation Angle, e is unit vector, and the zero sequence of net side system after only being compensated with capacitive element, positive sequence are obtained according to symmetrical component method and is born Sequence electric current；

Step 2：The object function of genetic algorithm is built, object function is metIts In：Obj is object function,Zero-sequence current real part respectively under three-phase four wire system, zero sequence electricity Flow imaginary part, forward-order current imaginary part, negative-sequence current real part and negative-sequence current imaginary part；

Step 3：Using genetic algorithm, the numerical value of minimum capacity unit builds and set as base unit using in practical engineering application The fixed identical quantity of population at individual number and Δ B_a,ΔB_b,ΔB_c,ΔB_ab,ΔB_bc,ΔB_caDirectly proportional, six binary systems Binary number that number is linked in sequence, new, is used as the individual in primary population；Wherein：ΔB_a,ΔB_b,ΔB_cFor three-phase star Type compensates the susceptance value of network, Δ B_ab,ΔB_bc,ΔB_caThe susceptance value of network is compensated for three-phase angle-style；

Step 4：Obtain in primary population individual after, using the objective function Equation calculating target function value in step 2, Individual adaptation degree is calculated, and calculates the hereditary probability of each individual；For the individual in primary population, the heredity in the next generation The size of probability and object function is inversely proportional；

Step 5：Simulation gene is carried out according to the hereditary probability of the individual of each in population to intersect, restructuring and mutation process are obtained Make one group of minimum individual of target function value in step 2 in offspring individual, record and as the optimum individual in the present age；

Step 6：Repeat step four, step 5, relatively per generation optimum individual, are obtained in whole genetic process at least 500 times Optimum individual, by its according to step 3 reverse be changed to Δ B_a,ΔB_b,ΔB_c,ΔB_ab,ΔB_bc,ΔB_ca, that is, obtain capacitive element Compensate the optimal value of branch road；Wherein：ΔB_a,ΔB_b,ΔB_cFor the susceptance value of the star-like compensation network of three-phase, Δ B_ab,ΔB_bc,ΔB_ca The susceptance value of network is compensated for three-phase angle-style.

2. the line uncompensated load of a kind of Three phase four according to claim 1 only utilizes the compensation method of capacitive element, It is characterized in that：Zero sequence, positive sequence and negative-sequence current parameter described in step one are：

$\begin{array}{c}{I}_0^{*}=\frac{U}{3}\[\left(G_a-\frac{1}{2}{G}_b-\frac{1}{2}{G}_c+\frac{\sqrt{3}}{2}{B}_b-\frac{\sqrt{3}}{2}{B}_c+\frac{\sqrt{3}}{2}{\mathrm{\ΔB}}_b-\frac{\sqrt{3}}{2}{\mathrm{\ΔB}}_c\right)\\ +j\left(-\frac{\sqrt{3}}{2}{G}_b+\frac{\sqrt{3}}{2}{G}_c+B_a-\frac{1}{2}{B}_b-\frac{1}{2}{B}_c+{\mathrm{\ΔB}}_a-\frac{1}{2}{\mathrm{\ΔB}}_b-\frac{1}{2}{\mathrm{\ΔB}}_c\right)\]\end{array}$

$I_{+}^{*}=\frac{U}{3}\[(\left(G_a+G_b+G_c\right)+j\left(B_a+B_b+B_c+{\mathrm{\ΔB}}_a+{\mathrm{\ΔB}}_b+{\mathrm{\ΔB}}_c+3{\mathrm{\ΔB}}_{ab}+3{\mathrm{\ΔB}}_{bc}+3{\mathrm{\ΔB}}_{ca}\right)\]$

$\begin{array}{c}{I}_{-}^{*}=\frac{U}{3}\[\left(G_a-\frac{1}{2}{G}_b-\frac{1}{2}{G}_c-\frac{\sqrt{3}}{2}{B}_b+\frac{\sqrt{3}}{2}{B}_c-\frac{\sqrt{3}}{2}{\mathrm{\ΔB}}_b+\frac{\sqrt{3}}{2}{\mathrm{\ΔB}}_c-\frac{3\sqrt{3}}{2}{\mathrm{\ΔB}}_{ab}+\frac{3\sqrt{3}}{2}{\mathrm{\ΔB}}_{ca}\right)\\ +j\left(\frac{\sqrt{3}}{2}{G}_b-\frac{\sqrt{3}}{2}{G}_c+B_a-\frac{1}{2}{B}_b-\frac{1}{2}{B}_c+{\mathrm{\ΔB}}_a-\frac{1}{2}{\mathrm{\ΔB}}_b-\frac{1}{2}{\mathrm{\ΔB}}_c+\frac{3}{2}{\mathrm{\ΔB}}_{ab}-3{\mathrm{\ΔB}}_{bc}+\frac{3}{2}{\mathrm{\ΔB}}_{ca}\right)\]\end{array}.$

Wherein：U is phase voltage amplitude,Respectively zero sequence, positive sequence and negative-sequence current, G_a,G_b,G_cFor the star-like load of three-phase Conductance, B_a,B_b,B_cFor the susceptance of the star-like load of three-phase, Δ B_a,ΔB_b,ΔB_cFor the susceptance value of the star-like compensation network of three-phase, Δ B_ab,ΔB_bc,ΔB_caThe susceptance value of network is compensated for three-phase angle-style, j is plural imaginary part unit.

3. the line uncompensated load of a kind of Three phase four according to claim 1 or 2 only utilizes the compensation side of capacitive element Method, it is characterised in that：The object function in step 2 is optimized using genetic algorithm.

4. the line uncompensated load of a kind of Three phase four according to claim 1 only utilizes the compensation method of capacitive element, It is characterized in that：Primary population at individual described in step 3 need to meet following condition：

1) each individual is continuous 6 binary numbers in population, and Δ B is represented respectively_a,ΔB_b,ΔB_c,ΔB_ab,ΔB_bc,ΔB_ca One group of new binary system of composition is connected, wherein；ΔB_a,ΔB_b,ΔB_cFor the susceptance value of the star-like compensation network of three-phase, Δ B_ab,Δ B_bc,ΔB_caThe susceptance value of network is compensated for three-phase angle-style；

2) scope of the value for the capacitor bank that the scope of the value of each of three binary numbers possesses with three-phase four wire system, That is 0 ＜ Δ B ＜ B_maxIt is corresponding, wherein：Δ B is any one susceptance value, B in compensation network_maxTo be mended in practical engineering application Repay the maximum susceptance value that any one phase of network can be compensated；

3) least unit of binary number, i.e., 1 are corresponding with the minimum unit value of three-phase four wire system capacitor bank.

5. the line uncompensated load of a kind of Three phase four according to claim 1 only utilizes the compensation method of capacitive element, It is characterized in that：The fitness of primary population at individual described in step 4 is defined as：Wherein：Fit is fitness, Obj is the object function in step 2.