Submerged arc furnace electrode voltage calculation model and construction method thereof, and submerged arc furnace electrode control method

Abstract

The application discloses a construction method of a calculation model of an electrode voltage of a mineral heat furnace, relates to the technical field of electrode control of the mineral heat furnace, and ingeniously constructs the calculation model of the electrode voltage calculated by the line voltage through vector calculation. The model can be used to realize non-contact calculation of the electrode voltage, accurately restore the phase voltage without physical contact with the electrode or the furnace charge, reduce the maintenance cost of the sensor, and prolong the service life of the equipment. The virtual neutral point used by the application drifts with the working condition, and can more truly reflect the state in the furnace. The application further provides a control method of the electrode of the mineral heat furnace, which adopts the calculation model, can reflect the change of the electrode-furnace charge contact impedance according to the real-time phase voltage calculation value, and then makes adjustment in time, and enhances the robustness of the system.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of electric arc furnace electrode control, in particular to an electric arc furnace electrode voltage calculation model and a construction method thereof, and a control method of the electric arc furnace electrode. BACKGROUND

[0002] The electric arc furnace (also known as arc resistance furnace or submerged arc furnace) is a high-temperature metallurgical equipment that converts electrical energy into heat energy, mainly used for producing industrial raw materials such as ferroalloy (such as ferrosilicon, ferromanganese), calcium carbide, yellow phosphorus, etc. Its core principle is to use the electric arc heat generated between the electrode and the furnace charge and the furnace charge resistance heat to raise the temperature in the furnace to above 1800℃, realizing ore reduction, melting and chemical reaction. The electric arc furnace is usually composed of a furnace body, an electrode system (self-baking or pre-baked electrode), a short net (a large current power transmission system), a transformer and an automatic control system. The electrode, as the core carrier of energy input, its position control and the stability of voltage and current parameters directly affect the thermal balance in the furnace and the production efficiency.

[0003] The electrode voltage measurement is a key link of the electric arc furnace control system, mainly used for electrode regulation, power optimization and fault diagnosis. In the prior art, the detection of the electrode voltage, i.e. the phase voltage, has two kinds of contact measurement and non-contact measurement. The contact measurement is to directly collect the voltage signal between the electrode and the furnace bottom (or the adjacent electrode) through a voltage transformer or a voltage divider, which is relatively mature in technology but still has limitations. For example, in a strong electromagnetic interference and high temperature environment, signal distortion is easy to occur, and the contact point is easy to oxidize or burn out, resulting in high maintenance cost. Moreover, the contact measurement simply takes the potential difference between the electrode top holder and the furnace bottom as the electrode voltage, which is inaccurate, on the one hand, it cannot accurately reflect the amplitude of the electrode voltage, on the other hand, it cannot accurately describe the drift of the neutral point in the furnace with the working condition changes. The non-contact measurement technology usually adopts infrared temperature measurement and laser positioning, combining the infrared thermal imager and laser range finder of the electrode position to indirectly calculate the voltage distribution, but it depends on the algorithm accuracy and is affected by the dust in the furnace. SUMMARY

[0004] The present application aims to provide an electric arc furnace electrode voltage calculation model and a construction method thereof, which is simple and easy to operate, can cleverly calculate the three-phase electrode voltage through the line voltage, and truly reflects the actual furnace condition.

[0005] Another object of the present application is to provide a control method of the electric arc furnace electrode, which calculates the electrode voltage by using the above calculation model and adjusts the operating condition in real time, has the advantages of high result accuracy, true reflection of the furnace condition and fast response.

[0006] The embodiments of the present application are implemented as follows:

[0007] A construction method of a model for calculating the voltage of an electrode of an electric arc furnace, comprising the following steps:

[0008] S1. Perform a symmetrical component transformation on the phase voltage of the three-phase electrode of the electric arc furnace to decompose into a positive sequence component , a negative sequence component , and a zero sequence component ;

[0009] S2. Eliminate the zero sequence component from the equations to construct a relationship between the line voltage , , of the three-phase electrode of the electric arc furnace and the positive sequence component , the negative sequence component ;

[0010] S3. Solve the positive sequence component and the negative sequence component ;

[0011] S4. Substitute the solved positive sequence component and the negative sequence component into the symmetrical component transformation formula, and set the zero sequence component to 0 to obtain a calculation model of the phase voltage of the three-phase electrode of the electric arc furnace.

[0012] A calculation model of the voltage of an electrode of an electric arc furnace, which is constructed by the construction method.

[0013] A control method of an electrode of an electric arc furnace, comprising:

[0014] S1. Measure the line voltage , , of the three-phase electrode of the electric arc furnace;

[0015] S2. Substitute into the calculation model of claim 7; and calculate the phase voltage , , of the three-phase electrode of the electric arc furnace;

[0016] S3. Adjust the furnace condition according to the phase voltage of the three-phase electrode of the electric arc furnace.

[0017] The beneficial effects of the embodiments of the present application are:

[0018] The embodiment of the present application provides a kind of construction method of calculating model of ore-heating furnace electrode voltage, which is cleverly constructed by vector calculation, and the calculating model of electrode voltage is calculated by line voltage.The model can be used to realize the non-contact calculation of electrode voltage, without physical contact electrode or charge, to accurately restore phase voltage, reduce sensor maintenance cost, and prolong equipment life.The virtual neutral point used by it drifts with working condition, and can more truly reflect the state in furnace.The embodiment of the present application also provides a kind of control method of ore-heating furnace electrode, which uses the above calculating model, can reflect the change of electrode-charging contact impedance according to real-time phase voltage calculation value, and then make adjustment in time, to enhance the robustness of system. DETAILED DESCRIPTION

[0019] To make the purpose, technical solutions and advantages of the embodiments of the present application clearer, the technical solutions in the embodiments of the present application will be described clearly and completely below. Obviously, the described embodiments are part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor fall within the scope of protection of the present application. Therefore, the following detailed description of the embodiments of the present application is not intended to limit the scope of the claimed present application, but only represents selected embodiments of the present application. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor fall within the scope of protection of the present application. EMBODIMENT

[0020] The embodiment provides a kind of ore-heating furnace electrode voltage calculating model, and its construction method includes the following steps:

[0021] S1. The phase voltage of three-phase electrode of ore-heating furnace is transformed into positive sequence component , negative sequence component And zero sequence component .

[0022] Wherein, the matrix form of symmetrical component transformation (formula one) is

[0023] .

[0024] S2. Eliminate zero sequence component , construct the relationship formula (formula two) between line voltage , , And positive sequence component , negative sequence component .

[0025] Further, the matrix of symmetrical component transformation is combined with the line voltage equation to obtain the relationship between the line voltage , , and the positive sequence component , the negative sequence component is

[0026] .

[0027] Because , , all include the zero sequence component , the zero sequence component is naturally eliminated in the process of subtraction, and the result of equation two is obtained.

[0028] S3. The positive sequence component and the negative sequence component are solved.

[0029] In this process, based on equation two, the rotation factor , is constructed, and the equation group (equation three) with a as the coefficient is constructed, that is

[0030] ,

[0031] The positive sequence component and the negative sequence component are solved again.

[0032] In actual calculation, because the three equations in equation three are linearly dependent, two equations can be selected to solve, for example, the equation containing and is used to solve, and the solution of the positive sequence component and the negative sequence component is

[0033] .

[0034] S4. The solved positive sequence component and the negative sequence component are substituted into the symmetrical component transformation formula (equation one), and the zero sequence component is set to 0 to obtain the calculation model of the phase voltage of the three-phase electrode of the electric arc furnace.

[0035] According to the actual operation of the electric arc furnace, the zero sequence current cannot flow, and there is no zero sequence loop, so in this calculation model, the zero sequence component can be forced to be 0 to simplify the calculation.

[0036] Further, the expression of the calculation model is

[0037] .

[0038] The calculation model constructs a virtual neutral point by mathematical method, the position of the virtual neutral point adjusts with the change of three-phase load, and can truly reflect the electrical balance state under actual working condition. Compared with the measurement error caused by the fixed reference point of the traditional method, the electrode lifting and power input can be more accurately controlled. Embodiments

[0039] The embodiment provides a control method of a submerged arc furnace electrode, which comprises:

[0040] S1. Measuring the line voltage of the three-phase electrode of the submerged arc furnace 、 、 ; S2. Substituting into the calculation model of embodiment 1; calculating the phase voltage of the three-phase electrode of the submerged arc furnace

[0041] 、 、 ; S3. Adjusting the furnace condition according to the phase voltage of the three-phase electrode of the submerged arc furnace.

[0042]

[0043] Further, the way of adjusting the furnace condition comprises controlling the lifting of a single electrode, and adjusting the input power of the electrode.

[0044] The application example adopts the calculation model of embodiment 1 to calculate the electrode voltage, and compares the result measured by the existing contact type electrode voltage measurement method (represented by ’、 ’、 ’), and compares the difference of the measurement results under different furnace conditions. The measurement results are shown in Table 1.

[0045] Table 1. Comparison of electrode voltage measurement results (voltage unit: V)

[0046]

[0047] ​​As can be seen from Table 1, under normal circumstances, the electrode voltage calculated by the calculation model of Example 1 is not much different from the result measured by the existing contact type electrode voltage measurement method, but in the event of an emergency, since the neutral point selected by the existing contact type method is generally a furnace shell, a furnace bottom buried conductive needle or a work site, which has nothing to do with the true furnace floating neutral point, so it cannot truly express the furnace condition. For example, in the case of a collapsed material near phase B, the existing measurement method cannot timely discover the change of the furnace condition, and cannot guide the furnace operator to timely adjust the furnace condition, resulting in a decrease in the arc work of the phase B electrode, an increase in the product unit consumption, and a decrease in the production. In addition, in the second furnace condition, when the phase A electrode ram is dead, the electrode voltage calculated by the present scheme decreases obviously, at this time, the phase A electrode should be lifted in time, and the electrode current should be reduced to avoid the occurrence of the furnace trip accident, while the result measured by the existing contact type measurement method only shows a slight decrease in the phase B electrode voltage, which cannot accurately identify the furnace condition, and further causes a production accident.

[0048] In summary, the embodiment of the present application provides a construction method of a submerged arc furnace electrode voltage calculation model, which ingeniously constructs a calculation model for calculating the electrode voltage by the line voltage through vector calculation. The model can realize non-contact calculation of the electrode voltage, and can accurately restore the phase voltage without physical contact with the electrode or the furnace charge, thereby reducing the sensor maintenance cost and prolonging the equipment life. The virtual neutral point used by the model drifts with the working condition, and can more truly reflect the furnace condition. The embodiment of the present application also provides a control method of a submerged arc furnace electrode, which uses the above calculation model, and can reflect the change of the electrode-furnace charge contact impedance according to the real-time phase voltage calculation value, and then make timely adjustment, thereby enhancing the robustness of the system.

[0049] The above only describes the preferred embodiments of the present application and is not used to limit the present application. For those skilled in the art, the present application can have various modifications and changes. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application shall be included in the protection scope of the present application.

Claims

1. A method for constructing a calculation model for electrode voltage in a submerged arc furnace, characterized in that, Includes the following steps: S1. Perform symmetrical component transformation on the phase voltages of the three-phase electrodes of the electric arc furnace, decomposing them into positive-sequence components. Negative order components and zero-order components ; S2. Eliminate the zero-sequence components by solving the simultaneous equations. Constructing the line voltage of the three-phase electrodes of the submerged arc furnace , , With orthogonal components Negative order components Relationships; S3. Solve for the positive-sequence components and negative order components ; S4. Solve for the positive-order components and negative order components Substituting into the symmetric component transformation formula, let the zero-sequence component... The value is 0, thus obtaining the calculation model for the phase voltage of the three-phase electrodes of the electric arc furnace; In step S1, the matrix form of the symmetric component transformation is: ； line voltage , , With orthogonal components Negative order components The relationship is ； In step S3, let the rotation factor be set. , , construct a A system of equations with coefficients ， Then solve for the positive sequence components. and negative order components .

2. The construction method according to claim 1, characterized in that, In step S3, the positive sequence component and negative order components The solution is 。 3. The construction method according to claim 2, characterized in that, In step S4, the expression of the calculation model is: 。 4. A calculation model for electrode voltage in a submerged arc furnace, characterized in that, It is constructed by the construction method described in any one of claims 1 to 3.

5. A method for controlling electrodes in a submerged arc furnace, characterized in that, include: S1. Measuring the line voltage of the three-phase electrodes of the electric arc furnace. , , ; S2. Substitute into the calculation model as described in claim 4; calculate the phase voltage of the three-phase electrodes of the electric arc furnace. , , ; S3. Adjust the furnace conditions according to the phase voltage of the three-phase electrodes of the electric arc furnace.

6. The control method according to claim 5, characterized in that, The methods for adjusting furnace conditions include controlling the raising and lowering of individual electrodes and adjusting the input power of the electrodes.

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