CN105205192A - Adaptive modeling device for three-phase alternating-current electric arc furnace and simulation algorithm thereof - Google Patents

Abstract

The invention relates to the field of electric energy quality analysis and control, in particular to an adaptive modeling device for a three-phase alternating-current electric arc furnace and a simulation algorithm thereof. The adaptive modeling device for the electric arc furnace can not only reflect the three-phase imbalance problem of the electric arc furnace, but also change model parameters according to changes of working conditions correspondingly to make the model parameters correspond to the working conditions. The simulation model parameters are optimized and adjusted according to the actual operating conditions to reflect the true electricity characteristics of the electric arc furnace more accurately, and then a theoretical basis is provided for studying electric arc furnace electric energy quality phenomena under different operating conditions and improving electric arc furnace load bearing capacity of a power grid.

Description

A kind of three-phase ac electric arc furnace adaptive modeling device and simulation algorithm thereof

Technical field

The present invention relates to power quality analysis and control field, be specially a kind of three-phase ac electric arc furnace adaptive modeling device and simulation algorithm thereof.

Background technology

In recent years, the increase of various nonlinear-load causes electric power quality problem day by day serious, jeopardizes the safety and economic operation of electric system.Ac arc furnace is typical nonlinear-load, is also to one of load that the quality of power supply has the greatest impact.

Electric arc furnaces modeling is the prerequisite of arc furnace power quality analytical work.Model whether accurate, rationally whether, can whether applicability determines by force follow-up work be launched smoothly.Electric arc furnaces operating condition is complicated and changeable, so need to set up a kind of electric arc furnaces model building device being applicable to various working.

Current electric arc furnaces model often supposes three-phase equilibrium, represents three-phase research with single-phase arc funace, mainly comprises nonlinear time-varying Resistance model for prediction, nonlinear time-varying voltage source model, based on the time-varying reactance model etc. of energy conservation.And actual arc stove three phase power unequal, three-phase imbalance problem is serious, carries out the electric arc furnaces model that above-mentioned hypothesis obtains and is difficult to reflection electric arc furnaces actual motion state.And this single-phase arc funace model often can not adjust according to the change of electric arc furnaces operating mode, cannot be corresponding with actual condition.

Summary of the invention

(1) technical matters that will solve

(1) according to the real-time adjustment model of the change of three phase power;

(2) the arc furnace power quality problem under different operating condition is studied.

(2) technical scheme

In order to solve the problems of the technologies described above, the invention provides a kind of three-phase ac electric arc furnace adaptive modeling device, it is characterized in that, described three-phase ac electric arc furnace adaptive modeling device comprises: bus 1, electric arc furnaces 3, tester 6, comprehensive modeling machine 7 and basic modeling engine 8; Described bus 1 is electrically connected with respectively transformer 2, electric arc furnaces 3 and voltage transformer (VT) 5; Described electric arc furnaces 3 is provided with current transformer 4; The secondary side of described voltage transformer (VT) 5 is electrically connected with the voltage waveform input end of described tester 6; The secondary side of described current transformer 4 is electrically connected with the current waveform input end of described tester 6; The data output end of described tester 6 is connected with the service data collection terminal of described comprehensive modeling machine 7; The model communication terminal of described basic modeling engine 8 is connected with the model communication terminal of described comprehensive modeling machine 7 by ethernet line 9.

In order to solve the problems of the technologies described above, the invention provides and a kind ofly apply the method that three-phase ac electric arc furnace adaptive modeling device carries out the emulation of three-phase ac electric arc furnace adaptive modeling, described method is divided into following steps:

Set up the three-phase ac electric arc furnace equivalent model of concentrated expression arc furnace power quality problem, containing the parameter needing to ask for according to actual condition in described equivalent model;

Equivalence is carried out to electric power system, and to the electric arc furnaces model simplification in the first step to facilitate calculating, and then set up electric arc furnaces simplified model and electric power system mathematical model thereof; Also can reflect the output characteristics of electric arc furnaces containing parameter to be determined in described electric arc furnaces simplified model;

According to supply line and transformer parameter, the mathematical model in electric arc furnaces three-phase operation power and second step, determines three-phawse arc furnace adaptive algorithm, in the hope of getting electric arc furnaces model parameter;

Model parameter is updated in electric arc furnaces model and completes modeling.

In order to solve the problems of the technologies described above, the invention provides a kind of application rights and requiring that the three-phase ac electric arc furnace adaptive modeling device described in 1 carries out three-phase ac electric arc furnace adaptive modeling method, said method comprising the steps of:

The first step, is electrically connected the voltage waveform input end of the secondary side of described voltage transformer (VT) 5 with described tester 6; The current waveform input end of the secondary side of described current transformer 9 with described tester 6 is electrically connected; The data output end of described tester 6 is connected with the service data collection terminal of described comprehensive modeling machine 7; The real-time running data of described tester 6 to described electric arc furnaces 2 is tested and is added up, and test data result is transferred to comprehensive modeling machine 7;

Second step, by the electric arc furnaces parameters input collected in described basic modeling engine 8; Described basic modeling engine 8 sets up according to the basic model of described electric arc furnaces 3 and typing parameter the equivalent model adapted with it; The equivalent model obtained being calculated through simplifying, forming corresponding mathematics model, by both-way communication, founding mathematical models being transferred in described comprehensive modeling machine 7;

3rd step, the mathematical model exported according to measured data and the basic modeling engine 8 of tester 6 described in first two steps; the computing of described comprehensive modeling machine 7 draws the unified model and parameter that are applicable to this electric arc furnaces operational system; finally draw the realistic model close to the true operating condition of described electric arc furnaces 3, and realize the function to model data derivation.

(3) beneficial effect

The adaptive modeling device of three-phawse arc furnace can not only reflect the three-phase imbalance problem of electric arc furnaces, and can change model parameter accordingly with corresponding with it according to the change of operating mode.The present invention to be optimized simulation parameters according to actual operating mode and to adjust, can more accurately reflect that electric arc furnaces truly uses electrical characteristics, thus be the arc furnace power quality phenomenon under the different operating condition of research, promote electrical network and receive arc furnace load ability, provide fundamental basis.

Accompanying drawing explanation

In order to be illustrated more clearly in the embodiment of the present invention or technical scheme of the prior art, be briefly described to the accompanying drawing used required in embodiment or description of the prior art below, apparently, accompanying drawing in the following describes is only some embodiments of the present invention, for those of ordinary skill in the art, under the prerequisite not paying creative work, other accompanying drawing can also be obtained according to these accompanying drawings.

Fig. 1 is the structural representation according to a kind of three-phase ac electric arc furnace adaptive modeling of the present invention device embodiment;

Fig. 2 exports I-V family curve according to the electric arc furnaces of a kind of three-phase ac electric arc furnace adaptive modeling of the present invention device embodiment;

Fig. 3 is the three-phase ac electric arc furnace model equivalent electrical circuit according to a kind of three-phase ac electric arc furnace adaptive modeling of the present invention device embodiment.

Embodiment

Below in conjunction with Figure of description and embodiment, the specific embodiment of the present invention is described in further detail.Following examples only for illustration of the present invention, but can not be used for limiting the scope of the invention.

The invention provides a kind of three-phase ac electric arc furnace adaptive modeling device, comprise bus 1, electric arc furnaces 3, tester 6, comprehensive modeling machine 7 and basic modeling engine 8.Bus 1 is electrically connected with transformer 2, electric arc furnaces 3 and voltage transformer (VT) 5 respectively; Electric arc furnaces 3 is provided with current transformer 4.The secondary side of voltage transformer (VT) 5 is electrically connected with the voltage waveform input end of tester 6; the secondary side of current transformer 9 is electrically connected with the current waveform input end of tester 6; the data output end of tester 6 is connected with the service data collection terminal of comprehensive modeling machine 7; the model communication terminal of basis modeling engine 8 is connected with the model communication terminal of comprehensive modeling machine 7 by ethernet line 9, realizes both-way communication.

The invention provides a kind of three-phase ac electric arc furnace adaptive modeling method, comprise the following steps:

The first step, the secondary side of voltage transformer (VT) 5 to be electrically connected with the voltage waveform input end of tester 6; the secondary side of current transformer 9 is electrically connected with the current waveform input end of tester 6, and the data output end of tester 6 is connected with the service data collection terminal of comprehensive modeling machine 7.The real-time running data of tester 6 pairs of electric arc furnaces 2 is tested and is added up, and test data result is transferred to comprehensive modeling machine 7.

Second step, by the electric arc furnaces parameters input collected in basic modeling engine 8; basis modeling engine 8 is according to the basic model of electric arc furnaces 3 and typing parameter; set up the equivalent model adapted with it; and calculate through simplifying; form corresponding mathematics model, by both-way communication, founding mathematical models is transferred in comprehensive modeling machine 7.

3rd step, the mathematical model exported according to measured data and the basic modeling engine 8 of tester 6 in first two steps; comprehensive modeling machine 7 computing draws the unified model and parameter that are applicable to this electric arc furnaces operational system; finally draw close to electric arc furnaces 3 it is really the realistic model of operating condition, and the statistical conversion function that supplies a model.

A kind of three-phase ac electric arc furnace adaptive modeling simulation algorithm, comprises the following steps:

The first step: the three-phase ac electric arc furnace equivalent model setting up concentrated expression arc furnace power quality problem, containing the parameter needing to ask for according to actual condition in equivalent model.

Electric arc furnaces exports I-V family curve as shown in Figure 2, and the relation as seen from the figure between electric arc furnaces voltage and electric current is nonlinear, and this makes modeling very difficult.For this reason, staging treating is carried out.First stage: electric arc starts to light, when arc voltage is elevated to zero, electric current is zero crossing also.Equivalent electrical circuit can be regarded as an open circuit, and leakage current exists, in this stage with a constant resistance (V _g/ i _g) relation of voltage and current is described; Subordinate phase: electric arc is set up, in arc-melting process, arc voltage declines suddenly, then tends towards stability.This process describes with the reciprocal function of time constant (b1) with one.Phase III, electric arc starts to extinguish, the decline that arc voltage is milder.This process still describes with a reciprocal function, wherein with time constant be b2.Obtain the mathematical model (for A phase) of the electric arc furnaces output characteristics as shown in formula (1) in sum.

$V_a\left(t\right)=\left\{\begin{array}{cc}\frac{V_g}{i_g}{i}_a\left(t\right)& 0\&le;\left|i_a\left(t\right)\right|<i_g\&\frac{d\left|i_a\left(t\right)\right|}{\mathrm{dt}}>0\\ [V_{d1}+\frac{(V_g-V_{d1})b_1}{b_1+\left|i_a\left(t\right)\right|-i_g}]\frac{i_a\left(t\right)}{\left|i_a\left(t\right)\right|}& \left|i_a\left(t\right)\right|\&GreaterEqual;i_g\&\frac{d\left|i_a\left(t\right)\right|}{\mathrm{dt}}>0\\ [V_{t1}+\frac{(V_g-V_{t1})b_2}{b_2+\left|i_a\left(t\right)\right|}]\frac{i_a\left(t\right)}{\left|i_a\left(t\right)\right|+i_g}& \left|i_a\left(t\right)\right|\&GreaterEqual;i_g\&\frac{d\left|i_a\left(t\right)\right|}{\mathrm{dt}}<0\end{array}\right.---\left(1\right)$

Wherein i _mfor the amplitude of electric current, unit is ampere; i _gfor invariable current, unit is ampere, V _gfor fixed voltage; B1 and b2 is time constant; V _at () is A phase electric arc furnaces voltage, unit is volt, i _at () is A phase current, unit is ampere; V _d1for electric arc furnaces magnitude of voltage when electric current trends towards maximal value, unit is volt.

Second step: equivalence is carried out to electric power system, and to the electric arc furnaces model simplification in the first step to facilitate calculating, and then set up electric arc furnaces and electric power system mathematical model thereof.The output characteristics of electric arc furnaces wherein also can be reflected in electric arc furnaces simplified model containing parameter to be determined.

The equivalent circuit diagram of electric arc furnaces and electric power system thereof as shown in Figure 3.Wherein, in order to three-phawse arc furnace model simplification is by convenience of calculation:

$V_a\left(t\right)=\left\{\begin{array}{cc}{V}_{d1}& i_a\left(t\right)\&GreaterEqual;0\\ -V_{d1}& i_a\left(t\right)<0\end{array}\right.---\left(2\right)$

$V_b\left(t\right)=\left\{\begin{array}{cc}{V}_{d2}& i_b\left(t\right)\&GreaterEqual;0\\ -V_{d2}& i_b\left(t\right)<0\end{array}\right.---\left(3\right)$

$V_c\left(t\right)=\left\{\begin{array}{cc}{V}_{d3}& i_c\left(t\right)\&GreaterEqual;0\\ -V_{d3}& i_c\left(t\right)<0\end{array}\right.---\left(4\right)$

In formula, V _a(t), V _b(t), V _ct () is respectively electric arc furnaces A, B, C phase voltage, unit is volt; V _d1, V _d2, V _d3be respectively electric arc furnaces voltage corresponding when A, B, C phase current trends towards maximal value, unit is volt.

Can obtain according to Fig. 3 and Thevenin theorem:

$i_a\left(t\right)R+L\frac{{\mathrm{di}}_a\left(t\right)}{\mathrm{dt}}=U_A+\frac{{-2V}_a\left(t\right)+V_b\left(t\right)+V_c\left(t\right)}{3}---\left(5\right)$

$i_b\left(t\right)R+L\frac{{\mathrm{di}}_b\left(t\right)}{\mathrm{dt}}=U_B+\frac{V_a\left(t\right)-2V_b\left(t\right)+V_c\left(t\right)}{3}---\left(6\right)$

$i_c\left(t\right)R+L\frac{{\mathrm{di}}_c\left(t\right)}{\mathrm{dt}}=U_C+\frac{V_a\left(t\right)+V_b\left(t\right){-2V}_c\left(t\right)}{3}---\left(7\right)$

Wherein R and L represents electric power system line resistance and the inductance reduction value to Circuit Fault on Secondary Transformer respectively, and unit is respectively ohm and henry.U _a, U _b, U _cfor supply voltage reduction is to the three-phase voltage of Circuit Fault on Secondary Transformer, expression formula is:

U _A＝U _msin(wt)、 $U_B=U_m\sin (\mathrm{wt}-\frac{2\mathrm{\&pi;}}{3}),U_C=U_m\sin (\mathrm{wt}-\frac{4\mathrm{\&pi;}}{3})$

3rd step: according to supply line and transformer parameter, the mathematical model in electric arc furnaces three-phase operation power and second step, determines three-phawse arc furnace adaptive algorithm, in the hope of getting electric arc furnaces model parameter.

Because of the discrete function that Va, Vb, Vc are about the time, be inconvenient to calculate, carried out Fourier decomposition and get first 4:

Wherein represent three-phase current i respectively _a, i _b, i _cinitial phase angle.

It is brought into respectively in formula (5) ~ (7), the expression formula of ia, ib, ic can be tried to achieve, then try to achieve P _a, P _b, P _cexpression formula.As follows:

Wherein

$\mathrm{\&phi;}=\arctan \frac{\mathrm{awL}}{R}$

Wherein

Because so can obtain according to formula (11)-(13):

Pa, Pb, Pc is made to equal electric arc furnaces three-phase actual motion power P _a,n, P _b,n, P _c,n, other three can be obtained and describe V _d1, V _d2, V _d3, equation:

Process of iteration is utilized to ask the system of equations be made up of equation (17) ~ (22) that V corresponding to actual motion power can be tried to achieve _d1, V _d2, V _d3value.Thus the self-adaptation achieved corresponding to the parameter of actual condition is asked for.This algorithm can be utilized to ask for corresponding model parameter whenever operating mode changes.

4th: the model parameter value asked in the 3rd step is substituted into formula (1), obtain the triphase flow reflecting electric arc furnaces actual motion state.

In conjunction with actual power situation, adopt the model of above-mentioned foundation can analyze arc furnace power quality relevant issues under different operating mode.

This model building device and emulation mode thereof are based on conventional electric energy quality test instrument and Modeling Analysis System, and connection type is simple, and focus on simulation calculation and be combined with measured data, modeling and simulating visual result is accurate.

Above embodiment is only for illustration of the present invention, but not limitation of the present invention.Although with reference to embodiment to invention has been detailed description, those of ordinary skill in the art is to be understood that, various combination, amendment or equivalent replacement are carried out to technical scheme of the present invention, do not depart from the spirit and scope of technical solution of the present invention, all should be encompassed in the middle of right of the present invention.

Claims (3)

1. a three-phase ac electric arc furnace adaptive modeling device, it is characterized in that, described three-phase ac electric arc furnace adaptive modeling device comprises: bus (1), electric arc furnaces (3), tester (6), comprehensive modeling machine (7) and basic modeling engine (8); Described bus (1) is electrically connected with respectively transformer (2), electric arc furnaces (3) and voltage transformer (VT) (5); Described electric arc furnaces (3) is provided with current transformer (4); The secondary side of described voltage transformer (VT) (5) is electrically connected with the voltage waveform input end of described tester (6); The secondary side of described current transformer (4) is electrically connected with the current waveform input end of described tester (6); The data output end of described tester (6) is connected with the service data collection terminal of described comprehensive modeling machine (7); The model communication terminal of described basic modeling engine (8) is connected with the model communication terminal of described comprehensive modeling machine (7) by ethernet line (9).

2. application rights requires that the three-phase ac electric arc furnace adaptive modeling device described in 1 carries out a method for three-phase ac electric arc furnace adaptive modeling emulation, and described method is divided into following steps:

Set up the three-phase ac electric arc furnace equivalent model of concentrated expression arc furnace power quality problem, containing the parameter needing to ask for according to actual condition in described equivalent model;

Equivalence is carried out to electric power system, and to the electric arc furnaces model simplification in the first step to facilitate calculating, and then set up electric arc furnaces simplified model and electric power system mathematical model thereof; Also can reflect the output characteristics of electric arc furnaces containing parameter to be determined in described electric arc furnaces simplified model;

According to supply line and transformer parameter, the mathematical model in electric arc furnaces three-phase operation power and second step, determines three-phawse arc furnace adaptive algorithm, in the hope of getting electric arc furnaces model parameter;

Model parameter is updated in electric arc furnaces model and completes modeling.

3. application rights requires that the three-phase ac electric arc furnace adaptive modeling device described in 1 carries out a three-phase ac electric arc furnace adaptive modeling method, said method comprising the steps of:

The first step, is electrically connected the voltage waveform input end of the secondary side of described voltage transformer (VT) (5) with described tester (6); The current waveform input end of the secondary side of described current transformer (9) with described tester (6) is electrically connected; The data output end of described tester (6) is connected with the service data collection terminal of described comprehensive modeling machine (7); The real-time running data of described tester (6) to described electric arc furnaces (2) is tested and is added up, and test data result is transferred to comprehensive modeling machine (7);

Second step, by the electric arc furnaces parameters input collected in described basic modeling engine (8); Described basic modeling engine (8) sets up according to the basic model of described electric arc furnaces (3) and typing parameter the equivalent model adapted with it; The equivalent model obtained being calculated through simplifying, forming corresponding mathematics model, by both-way communication, founding mathematical models being transferred in described comprehensive modeling machine (7);

3rd step, the mathematical model exported according to measured data and the basic modeling engine (8) of tester described in first two steps (6); the computing of described comprehensive modeling machine (7) draws the unified model and parameter that are applicable to this electric arc furnaces operational system; finally draw the realistic model close to the true operating condition of described electric arc furnaces (3), and realize the function to model data derivation.