A method and system for predicting reactive power of DC arc furnace

Abstract

The invention discloses a reactive power prediction method and system for a DC electric arc furnace, and relates to the field of data analysis. The main scheme is: according to the working voltage, working current, power factor, reactive power component one, reactive power component two, reactive power component three, reactive power component four, reactive power component five and reactive power component six of the DC electric arc furnace, the reactive power prediction value is calculated, and the problem that data collection is mainly concentrated on the most basic electrical parameters, while data collection of some indirect factors affecting reactive power is insufficient, thus affecting the accuracy of reactive power prediction is solved. Whether the working state of the DC electric arc furnace is normal is judged according to the reactive power change value and the reactive power change threshold, which provides a specific judgment basis for the staff, is conducive to timely discovery of problems and prevention of major failures.

Description

Technical Field

[0001] The present invention relates to the technical field of data analysis, and in particular to a method and system for predicting reactive power of a direct current arc furnace. Background Art

[0002] In the field of steel smelting, abnormal changes in reactive power may cause problems such as equipment overload and overheating, affecting the service life and safety of the equipment. By predicting reactive power, potential equipment failure risks can be discovered in a timely manner and preventive measures can be taken in advance. This is of great significance for the normal operation of equipment, product quality control and improvement of production efficiency in the steel smelting process.

[0003] The working principle of the traditional reactive power prediction method is: install sensors on the DC arc furnace power supply circuit, collect the time domain waveform data of voltage and current through the sensors, and analyze and calculate the time domain waveform data of voltage and current to realize the prediction of reactive power.

[0004] The existing technology still has the following deficiencies: data collection for reactive power prediction of DC arc furnaces mainly focuses on the most basic electrical parameters, such as voltage, current, etc., while data collection for some indirect factors affecting reactive power is insufficient, thus affecting the accuracy of reactive power prediction. Summary of the invention

[0005] 1. Technical issues to be resolved

[0006] In view of the shortcomings of the prior art, the present invention provides a method for predicting reactive power of a DC arc furnace by , Working current , Power Factor , reactive power component 1 、Reactive power component 2 , reactive power component three , reactive power component 4 , reactive power component 5 and reactive power component VI Calculate reactive power forecast , which solves the problem that data collection is mainly focused on the most basic electrical parameters, while insufficient data collection is conducted on some indirect factors affecting reactive power, thus affecting the accuracy of reactive power prediction.

[0007] (II) Technical solution

[0008] To achieve the above objectives, the present invention is implemented through the following technical solutions: A method for predicting reactive power of a DC arc furnace, comprising the following steps:

[0009] Collect electrical parameter data, arc data, harmonic data, charge data, environmental data, wind direction data and electrode data;

[0010] Calculation of reactive power components based on arc data ; Calculate reactive power component 2 based on harmonic data ; Calculate the charge resistance based on charge data ; According to the phase difference after the charge characteristics , DC arc furnace working voltage and charge resistance Calculation of reactive power components III ; Calculate equivalent resistance based on electrical parameter data , according to the equivalent resistance , electrical parameter data and environmental data to calculate temperature equivalent resistance , humidity equivalent resistance , Dust adhesion equivalent resistance and air mass equivalent resistance , and further calculate the reactive power component four ; Calculate reactive power component 5 based on wind direction data ; Calculate reactive power change based on electrical parameter data and electrode data And reactive power change , and further calculate the reactive power component six ;

[0011] According to the electrical parameter data, reactive power component 、Reactive power component 2 , reactive power component three , reactive power component 4 , reactive power component 5 and reactive power component VI Calculate reactive power forecast ; Get the current reactive power , according to the reactive power prediction value and the current reactive power Calculate reactive power change ; Preset reactive power change threshold ; According to the reactive power change value and reactive power change threshold Determine whether the working status of the DC arc furnace is normal; alarm when the working status is abnormal.

[0012] In the preferred embodiment of the reactive power prediction method of a DC arc furnace, the reactive power component is calculated. The method is:

[0013] Arc data including arc voltage , arc current and arc active power ;

[0014] Calculate reactive power components based on arc data , the formula based on is:

[0015] .

[0016] In the preferred embodiment of the reactive power prediction method of a DC arc furnace, the reactive power component is calculated. The method is:

[0017] Harmonic data including harmonic voltage RMS values , harmonic current effective value and phase difference ;

[0018] Calculate reactive power components based on harmonic data II , the formula based on is:

[0019]

[0020] in, For the The effective value of the voltage of the subharmonic, is the serial number corresponding to different harmonics, and its value is ; is the number of different harmonics, which is a positive integer; For the The phase difference between subharmonic voltage and current; For the The effective value of the subharmonic current.

[0021] In the preferred embodiment of the reactive power prediction method of a DC arc furnace, the reactive power component three is calculated. The method is:

[0022] Charge data including charge volume fraction 、Charge resistance And the phase difference after considering the characteristics of the charge ;

[0023] According to the volume fraction of the charge and charge resistance Calculate the charge resistance , the formula based on is:

[0024]

[0025] in, For the furnace The volume fraction of the components, is the serial number corresponding to different components, and its value is , is the total number of different components in the furnace, The value is a positive integer; For the furnace The resistance of the component;

[0026] The electrical parameter data at least includes the DC arc furnace operating voltage ;

[0027] According to the phase difference after considering the characteristics of the charge , DC arc furnace working voltage and charge resistance Calculation of reactive power components III , the formula based on is:

[0028] .

[0029] In the preferred embodiment of the reactive power prediction method of a DC arc furnace, the equivalent resistance is calculated. The method is:

[0030] The electrical parameter data also includes the initial series element resistance of the DC arc furnace and the initial parallel branch resistance ;

[0031] According to the resistance of the series element and parallel branch resistance Calculate the equivalent resistance , the formula based on is:

[0032]

[0033] in, For the The initial resistance of the series element is is the serial number corresponding to different series elements, and its value is , is the number of series elements, which is a positive integer; For the The initial resistance of the parallel branch is is the serial number corresponding to different parallel branches, and its value is ; is the number of parallel branches.

[0034] In the preferred embodiment of the reactive power prediction method of a DC arc furnace, the reactive power component is calculated. The method is:

[0035] Electrical parameter data also includes DC arc furnace operating current and working reactance ;

[0036] Environmental data including operating temperature , Working humidity , Dust adhesion area and air quality index ;

[0037] According to the equivalent resistance and operating temperature Calculate Temperature Equivalent Resistance , the formula based on is:

[0038]

[0039] in, is the temperature coefficient; is the base temperature;

[0040] According to the equivalent resistance and operating humidity Calculating humidity equivalent resistance , the formula based on is:

[0041]

[0042] in, is the humidity coefficient; is the basic humidity;

[0043] According to the equivalent resistance , dust adhesion coefficient and dust adhesion area Calculation of dust adhesion equivalent resistance , the formula based on is:

[0044]

[0045] in, is the dust adhesion coefficient;

[0046] According to the DC arc furnace working current , equivalent resistance and air quality index Calculate the air mass equivalent resistance , the formula based on is:

[0047]

[0048] in, is the air quality impact coefficient; As the basic air quality index;

[0049] According to the DC arc furnace working voltage , working reactance , Temperature Equivalent Resistance , humidity equivalent resistance , Dust adhesion equivalent resistance and air mass equivalent resistance , calculate the reactive power component four , the formula based on is:

[0050]

[0051] in, is the dielectric loss factor.

[0052] In the preferred embodiment of the reactive power prediction method of a DC arc furnace, the reactive power component V is calculated. The method is:

[0053] Wind direction data including wind speed , wind direction and arc angle , Phase difference when there is no wind and the current phase difference ;

[0054] Calculate reactive power components based on wind direction data , the formula based on is:

[0055]

[0056] in, is the wind direction data influence coefficient.

[0057] In the preferred embodiment of the reactive power prediction method of a DC arc furnace, the reactive power component VI is calculated. The method is:

[0058] The electrical parameter data also includes the power supply angular frequency ,inductance , Power Factor and arc resistance ;

[0059] Electrode data includes electrode position change , electrode current , electrode resistance and electrode inductance ;

[0060] According to the DC arc furnace working voltage , power supply angular frequency ,inductance , Power Factor , electrode position change and arc resistance Calculate reactive power change , the formula based on is:

[0061]

[0062] in, is the arc length adjustment factor; is the electrode position adjustment coefficient;

[0063] According to the DC arc furnace working current , Power Factor , electrode current , electrode resistance and electrode inductance Calculate reactive power change 2 , the formula based on is:

[0064]

[0065] in, is the unit time;

[0066] According to the reactive power change And calculate the reactive power change Calculation of reactive power components VI , the formula based on is:

[0067] .

[0068] In the preferred embodiment of the reactive power prediction method of a DC arc furnace, according to the reactive power change value and reactive power change threshold The method to judge whether the working state of DC arc furnace is normal is:

[0069] According to the DC arc furnace working voltage , Working current , Power Factor , reactive power component 1 、Reactive power component 2 , reactive power component three , reactive power component 4 , reactive power component 5 and reactive power component VI Calculate reactive power forecast , the formula based on is:

[0070]

[0071] in, For the The influencing factors corresponding to the reactive power components and The interaction coefficient of the influencing factors corresponding to the reactive power components, and is the serial number corresponding to different reactive power components, ranging from 1 to 6; ; It is Reactive power component; It is Reactive power component;

[0072] According to the reactive power prediction value and the current reactive power Calculate reactive power change , the formula based on is:

[0073]

[0074] According to the reactive power change value and reactive power change threshold The standards for judging whether the working state of a DC arc furnace is normal are:

[0075] .

[0076] The present invention also discloses a DC arc furnace reactive power prediction system, which is used to implement the above prediction method, and comprises:

[0077] Data acquisition module, used to collect electrical parameter data, arc data, harmonic data, charge data, environmental data, wind direction data and electrode data;

[0078] Calculation module, capable of calculating reactive power components based on arc data ; Calculate reactive power component 2 based on harmonic data ; Calculate the charge resistance based on charge data ; According to the phase difference after the charge characteristics , DC arc furnace working voltage and charge resistance Calculation of reactive power components III ; Calculate equivalent resistance based on electrical parameter data ; According to the equivalent resistance , electrical parameter data and environmental data to calculate temperature equivalent resistance , humidity equivalent resistance , Dust adhesion equivalent resistance and air mass equivalent resistance , and further calculate the reactive power component four ; Calculate reactive power component 5 based on wind direction data ; Calculate reactive power change based on electrical parameter data and electrode data And reactive power change , and further calculate the reactive power component six ;

[0079] The prediction module can 、Reactive power component 2 , reactive power component three , reactive power component 4 , reactive power component 5 and reactive power component VI Calculate reactive power forecast ; Get the current reactive power , according to the reactive power prediction value and the current reactive power Calculate reactive power change ; Preset reactive power change threshold ; According to the reactive power change value and reactive power change threshold Determine whether the working status of the DC arc furnace is normal; alarm when the working status is abnormal.

[0080] (III) Beneficial effects

[0081] The present invention provides a method and system for predicting reactive power of a DC arc furnace, which has the following beneficial effects:

[0082] (1) By collecting electrical parameter data, arc data, harmonic data, charge data, environmental data, wind direction data and electrode data, it can provide multi-dimensional data for reactive power prediction and improve the accuracy of prediction;

[0083] (2) The arc is the core part of the DC arc furnace. The reactive power component is calculated based on the arc data. , can accurately capture the impact of the electrical characteristics of the arc in the furnace space on the reactive power of the entire DC arc furnace. Harmonics can cause problems such as overheating, vibration, and increased noise in electrical equipment. By calculating the reactive power component based on harmonic data, , can better assess the degree of harmonic damage to the equipment. The characteristics of the charge will change as the smelting process progresses. , DC arc furnace working voltage and charge resistance Calculation of reactive power components III , can help operators better understand the situation in the furnace and improve product quality and production efficiency. Calculate reactive power components using environmental data , we can more comprehensively understand the impact of the external environment on the reactive power of the DC arc furnace and provide a more accurate basis for the operation and maintenance of the equipment. , the effect of wind speed and wind direction on reactive power can be quantified. Reactive power components are calculated based on electrical parameter data and electrode data. , we can better understand the influence of factors such as electrode loss degree and position change on reactive power;

[0084] (3) According to the electrical parameter data, reactive power component 、Reactive power component 2 , reactive power component three , reactive power component 4 , reactive power component 5 and reactive power component VI Calculate reactive power forecast , increasing the diversity of data and solving the problem that data collection is mainly focused on the most basic electrical parameters, while insufficient data collection on some indirect factors affecting reactive power, thus affecting the accuracy of reactive power prediction. and reactive power change threshold Judging whether the working status of the DC arc furnace is normal provides staff with a specific basis for judgment, which is conducive to timely discovery of problems and prevention of major failures. BRIEF DESCRIPTION OF THE DRAWINGS

[0085] Figure 1 The present invention is a schematic diagram of the working steps of a method for predicting reactive power of a DC arc furnace. DETAILED DESCRIPTION

[0086] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0087] See also Figure 1 The present invention provides a method for predicting reactive power of a DC arc furnace, comprising the following steps:

[0088] Step 1: Collect electrical parameter data, arc data, harmonic data, charge data, environmental data, wind direction data and electrode data.

[0089] Combined with the content of step 1:

[0090] By collecting electrical parameter data, arc data, harmonic data, charge data, environmental data, wind direction data and electrode data, it is possible to provide multi-dimensional data for reactive power prediction and improve the accuracy of the prediction.

[0091] Step 2: Calculate reactive power components based on arc data ; Calculate reactive power component 2 based on harmonic data ; Calculate the charge resistance based on charge data ; According to the phase difference after the charge characteristics , DC arc furnace working voltage and charge resistance Calculation of reactive power components III ; Calculate equivalent resistance based on electrical parameter data , according to the equivalent resistance , electrical parameter data and environmental data to calculate temperature equivalent resistance , humidity equivalent resistance , Dust adhesion equivalent resistance and air mass equivalent resistance , and further calculate the reactive power component four ; Calculate reactive power component 5 based on wind direction data ; Calculate reactive power change based on electrical parameter data and electrode data And reactive power change , and further calculate the reactive power component six .

[0092] Step 201: Calculate reactive power component 1 The method is:

[0093] Arc data including arc voltage , arc current and arc active power .

[0094] It should be noted that the arc voltage It refers to the voltage drop across the arc in the furnace space, reflecting the electric field strength required for the arc to maintain combustion, and is measured by a voltage transformer or a photoelectric isolation sensor. It refers to the current value of the arc passing through the furnace space, reflecting the energy and heating capacity of the arc, and is measured by a current transformer. It refers to the power part used to heat the charge, melt the metal, etc. It is the product of the total input power of the electric arc furnace and the power factor; the space inside the furnace refers to the space between the electrode end and the charge, and this area is the main place where the arc is generated.

[0095] Calculate reactive power components based on arc data , the formula based on is:

[0096]

[0097] It should be noted that this formula is based on the power triangle principle, that is: apparent power . Through the arc voltage , arc current and arc active power The reactive power component is calculated as , taking into account the influence of the arc's own characteristics on reactive power.

[0098] Step 202: Calculate reactive power component 2 The method is:

[0099] Harmonic data including harmonic voltage RMS , harmonic current effective value and phase difference .

[0100] It should be noted that the effective value of harmonic voltage Effective value of harmonic current It reflects the intensity of harmonics and is measured by a harmonic analyzer. A harmonic analyzer can perform spectrum analysis on the input voltage and current signals, separate the harmonic components, and measure their effective values. It refers to the phase difference between harmonic voltage and current, which is obtained by performing phase analysis on the measured harmonic voltage and current data.

[0101] Calculate reactive power components based on harmonic data II , the formula based on is:

[0102]

[0103] It should be noted that the operating principle of this formula is: DC arc furnaces will generate harmonic currents and harmonic voltages when working, and these harmonic components will generate additional reactive power in the circuit. According to the harmonic analysis theory, the reactive power of each harmonic is superimposed and summed to obtain the total harmonic reactive power. When it is 1, it means that the system has only fundamental wave and no harmonics, so The minimum is 2.

[0104] in, For the The effective value of the voltage of the subharmonic, is the serial number corresponding to different harmonics, and its value is ; is the number of different harmonics, which is a positive integer; For the The phase difference between subharmonic voltage and current, For the The effective value of the subharmonic current.

[0105] Step 203: Calculate reactive power component three The method is:

[0106] Charge data including charge volume fraction 、Charge resistance And the phase difference after considering the characteristics of the charge .

[0107] It should be noted that the charge volume fraction In order to add the volume fraction of each component to the charge, the proportion of each component is determined by chemical analysis, and then the volume fraction of each component is calculated based on the total volume of the charge. Refers to the resistance value of each charge component, obtained through experimental measurement. Phase difference after considering the characteristics of the charge It refers to the phase difference between voltage and current after considering the characteristics of the charge, and is obtained through real-time monitoring and phase analysis of the voltage and current data during the operation of the arc furnace.

[0108] According to the volume fraction of the charge and charge resistance Calculate the charge resistance , the formula based on is:

[0109]

[0110] It should be noted that the operating principle of this formula is: this formula is based on the mixing rule. When current passes through the charge, the conductivity of different components is different, which can be equivalent to multiple different resistors in parallel. According to the parallel resistance calculation formula, the charge resistance can be obtained .

[0111] in, For the furnace The volume fraction of the components, is the serial number corresponding to different components, and its value is , is the total number of different components in the furnace, The value is a positive integer; For the furnace The resistance of a component.

[0112] The electrical parameter data at least includes the DC arc furnace operating voltage . Operating voltage The voltage is measured in real time using a voltage measuring instrument.

[0113] According to the phase difference after considering the characteristics of the charge , DC arc furnace working voltage and charge resistance Calculation of reactive power components III , the formula based on is:

[0114]

[0115] It should be noted that the operating principle of this formula is that the composition of the charge affects its equivalent resistance and the interaction with the arc in the arc furnace, thus affecting the reactive power. According to Ohm's law and the definition of reactive power, by calculating the equivalent resistance of the charge and considering its influence on the phase difference, the reactive power components related to the charge characteristics are obtained. .

[0116] Step 204: Calculate the equivalent resistance The method is:

[0117] The electrical parameter data also includes the initial series element resistance of the DC arc furnace and the initial parallel branch resistance .

[0118] It should be noted that the initial series element resistance It refers to the base temperature of the DC arc furnace when it is not in use. , basic humidity , no dust pollution and basic air quality index The total resistance value of electrical components connected in series under certain conditions. The method of obtaining this value is to use a professional resistance measuring instrument, such as an ohmmeter, a bridge, etc., to measure each series component individually, and then calculate the total of the measured values. When measuring, it is necessary to ensure that the component is disconnected to avoid the influence of other circuit parts on the measurement results.

[0119] Initial parallel branch resistance It refers to the base temperature of the DC arc furnace when it is not in use. , basic humidity , free from dust pollution and basic air quality index The equivalent resistance value presented by electrical components or branches connected in parallel under certain conditions. The method of obtaining it is: use instruments such as current transformers and voltmeters to measure the current and voltage of each parallel branch respectively, and then calculate the resistance of each branch according to Ohm's law, and calculate the initial parallel branch resistance by calculating the sum of the resistances of each branch. .

[0120] Among them, the basic temperature The standard ambient temperature is usually 25 . Basic humidity Relative humidity in a dry environment, generally 25 The air quality index is used to measure the air quality, with a value of 0 to 500. The larger the value, the worse the air quality. The air quality index is determined by counting the concentrations of major pollutants in the air, such as ozone concentration, carbon monoxide concentration, and fine particulate matter concentration. Basic air quality index is 50.

[0121] According to the resistance of the series element and parallel branch resistance Calculate the equivalent resistance , the formula based on is:

[0122]

[0123] It should be noted that this formula calculates the resistance of all series components and parallel branch resistance The equivalent resistance is obtained by summing .

[0124] in, For the The initial resistance of the series element is is the serial number corresponding to different series elements, and its value is , is the number of series elements, which is a positive integer; For the The initial resistance of the parallel branch is is the serial number corresponding to different parallel branches, and its value is ; is the number of parallel branches.

[0125] Step 205: Calculate reactive power component 4 The method is:

[0126] Electrical parameter data also includes DC arc furnace operating current and working reactance .

[0127] It should be noted that the working current of the DC arc furnace It refers to the current through the arc furnace circuit during the normal operation of the DC arc furnace, measured using a current sensor. It refers to an electrical characteristic in the DC arc furnace circuit that hinders the change of current due to the presence of components such as inductance and capacitance. It is measured using an impedance analyzer.

[0128] Environmental data including operating temperature , Working humidity , Dust adhesion area and air quality index .

[0129] It should be noted that the operating temperature The working temperature of the DC arc furnace is obtained by temperature measuring devices such as thermocouples or infrared thermometers installed in the furnace. The water vapor content in the working environment of the DC arc furnace is determined by installing humidity sensors in the working area of ​​the DC arc furnace or in the electrical control room to monitor the ambient humidity in real time. Refers to the area covered by dust on the surface of the DC arc furnace equipment, insulating components, electrodes and other parts. It is determined by taking photos or videos of the DC arc furnace equipment with a camera or video camera, and then processing and analyzing the images with image analysis software. Air Quality Index It is an indicator used to measure the air quality status. The concentration of various pollutants is measured by air quality detectors and calculated according to a preset algorithm.

[0130] According to the equivalent resistance and operating temperature Calculate Temperature Equivalent Resistance , the formula based on is:

[0131]

[0132] It should be noted that the operating principle of this formula is: in a DC arc furnace, when the temperature changes, the resistance of the electrodes and connecting parts in the furnace will change. With basic temperature The difference between , quantify the effect of temperature change on resistance, and thus obtain the temperature equivalent resistance .

[0133] in, is the temperature coefficient. Different materials have different resistance temperature coefficients, which can be obtained by referring to the material manual or experimental measurement. The base temperature.

[0134] According to the equivalent resistance and operating humidity Calculating humidity equivalent resistance , the formula based on is:

[0135]

[0136] It should be noted that the operating principle of this formula is: in a DC arc furnace, when the ambient humidity changes, it will affect the surface resistance of the insulating material around the arc furnace and the degree of oxidation of some metal parts, thereby changing the equivalent resistance. With basic humidity The difference between , quantify the effect of humidity change on resistance, and thus obtain the humidity equivalent resistance .

[0137] in, The humidity coefficient is determined by experiments. Specifically, the humidity control box is used to simulate different humidity environments, and the corresponding resistance changes are measured to obtain the humidity coefficient. . The basic humidity.

[0138] According to the equivalent resistance , dust adhesion coefficient and dust adhesion area Calculation of dust adhesion equivalent resistance , the formula based on is:

[0139]

[0140] It should be noted that the operating principle of this formula is that dust adhering to the surface of the insulating parts of the arc furnace will change its resistance characteristics. When dust adheres to the surface of electrical equipment, it will reduce the insulation performance and reduce the insulation resistance. As the insulation resistance increases, it decreases in a certain proportion.

[0141] in, is the dust adhesion coefficient, which ranges from 0 to 1. It is determined by simulating environments with different dust concentrations in the laboratory, testing samples with known initial insulation resistance, and fitting the test results. The value of .

[0142] According to the DC arc furnace working current , equivalent resistance and air quality index Calculate the air mass equivalent resistance , the formula based on is:

[0143]

[0144] It should be noted that the operating principle of this formula is that air quality has an important influence on arc stability. The components in the air will change the dielectric environment around the arc, thereby affecting the resistance value and discharge characteristics. By calculating the air quality index Compared with the basic air quality index The difference between , quantify the effect of air quality changes on resistance, and thus obtain the air quality equivalent resistance .

[0145] in, The air quality influence coefficient is related to factors such as the oxygen content, impurity gas content, and air pressure in the air. The air quality influence coefficient is obtained by simulating different air qualities in the laboratory and measuring the corresponding resistance changes. . The basic air quality index.

[0146] According to the DC arc furnace working voltage , working reactance , Temperature Equivalent Resistance , humidity equivalent resistance , Dust adhesion equivalent resistance and air mass equivalent resistance , calculate the reactive power component four , the formula based on is:

[0147]

[0148] It should be noted that the operating principle of this formula is: environmental factors such as temperature, humidity, dust adhesion area and air quality will affect the reactive power by affecting the insulation performance of electrical equipment, arc characteristics, etc. A corresponding calculation model is established for each factor, and the contribution of each factor to the reactive power is calculated based on Ohm's law, power formula and consideration of dielectric characteristics, and then they are added together to obtain the total reactive power component of environmental factors. The base temperature , basic humidity , dust-free and basic air quality index The impedance angle under the condition, For temperature The impedance angle at To consider the phase difference after temperature influence, is the effect of temperature on reactive power. Humidity The impedance angle at To consider the phase difference after humidity influence, is the impact of humidity on reactive power. is the influence of dust adhesion area on reactive power, according to the dielectric loss factor Calculated. To consider the phase difference after air quality, is the impact of air quality on reactive power.

[0149] in, The dielectric loss factor indicates the degree of energy loss of an insulating material under the action of an AC electric field. It is determined by the properties of the insulating material and can be obtained through material manuals or experimental measurements.

[0150] Step 206: Calculate reactive power component 5 The method is:

[0151] Wind direction data including wind speed , wind direction and arc angle , Phase difference when there is no wind and the current phase difference .

[0152] It should be noted that the wind speed It refers to the air flow speed in the environment around the arc furnace, which is measured by an anemometer installed near the arc furnace. It describes the angular relationship between the wind direction and the arc direction. The wind direction is measured by the wind direction sensor and then calculated based on the actual direction of the arc. It refers to the phase difference between voltage and current when there is no wind influence. Current phase difference It refers to the phase difference between voltage and current at the current wind speed and wind direction. and the current phase difference Obtained through power monitoring equipment.

[0153] Calculate reactive power components based on wind direction data , the formula based on is:

[0154]

[0155] It should be noted that the operating principle of this formula is: when wind blows towards a DC arc furnace, the wind will exert force on the arc, thereby changing the shape, length and stability of the arc. According to the principles of fluid mechanics, the force exerted by the wind on the arc is proportional to the square of the wind speed and is related to the angle between the wind direction and the arc direction. Changes in wind direction and wind speed will also affect the heat dissipation around the arc, further changing the electrical characteristics and reactive power of the arc. The greater the interference of the wind on the arc, the greater the change in phase difference.

[0156] in, The wind direction data influence coefficient is obtained by running the arc furnace under different wind speed and wind direction conditions, recording the change of reactive power, and then using data fitting and other methods to obtain At the same time, it is also necessary to make regular corrections and optimizations according to the operation of the arc furnace and environmental changes.

[0157] Step 207: Calculate reactive power component VI The method is:

[0158] The electrical parameter data also includes the power supply angular frequency ,inductance , Power Factor and arc resistance .

[0159] It should be noted that the power supply angular frequency Measured using a frequency meter. Inductance It refers to the characteristic of hindering the change of current due to the existence of coils, transformer windings, arcs and other components in the circuit. It is obtained by directly measuring the inductance of the inductor components in the circuit using an inductance measuring instrument, such as an inductance meter or an impedance analyzer. Power factor It reflects the efficiency of electric energy utilization in the circuit. The higher the power factor, the smaller the reactive power in the circuit and the higher the efficiency of electric energy utilization. It is measured using a power factor meter. Measured using an arc resistance tester.

[0160] Electrode data includes electrode position change , electrode current , electrode resistance and electrode inductance .

[0161] It should be noted that the electrode position change Measured by the displacement sensor installed on the electrode lifting device. Electrode current Measured using a current transformer. Electrode resistance Measured by a resistance meter. Electrode inductance The calculation is done by performing high-frequency excitation experiments on the electrodes and measuring the responses of current and voltage.

[0162] According to the DC arc furnace working voltage , power supply angular frequency ,inductance , Power Factor , electrode position change and arc resistance Calculate reactive power change , the formula based on is:

[0163]

[0164] It should be noted that the operating principle of this formula is: when the electrode position changes, the arc length changes, and according to the physical characteristics of the arc, the arc resistance will change accordingly. According to Ohm's law and the definition of reactive power, in an AC circuit, reactive power is related to factors such as voltage, resistance, reactance, and phase difference. By calculating the change in arc resistance and other parameters in the circuit, the effect of electrode position change on reactive power is determined. When the arc resistance changes, the current distribution in the circuit will change, causing the phase difference between voltage and current to change, which in turn affects the reactive power.

[0165] in, is the arc length adjustment coefficient, which reflects the characteristics of the arc itself, such as the influence of factors such as the type of gas, pressure, and temperature of the arc on the relationship between resistance and length. The determination method is: under different arc furnace working conditions, change the arc length, measure the corresponding arc resistance, and then obtain it through data fitting. The value of . It is the electrode position adjustment coefficient, which reflects the relationship between the change in electrode position and the change in arc length. It depends on the geometric structure of the arc furnace and the movement mechanism of the electrode. It is preliminarily calculated according to the design drawings and geometric parameters of the equipment, and then verified and adjusted in actual operation.

[0166] According to the DC arc furnace working current , Power Factor , electrode current , electrode resistance and electrode inductance Calculate reactive power change 2 , the formula based on is:

[0167]

[0168] It should be noted that the operating principle of this formula is: the resistance of the electrode will cause active power loss when the current passes through, and it will also affect the phase difference between the voltage and the current, thereby generating reactive power. The inductance characteristics of the electrode will generate an induced electromotive force when the current changes, and this induced electromotive force will also interact with the current to generate reactive power. By considering the changes in the resistance, inductance and current of the electrode, the voltage drop and reactive power on the electrode are calculated.

[0169] in, It is the unit time and is determined according to the acquisition frequency.

[0170] According to the reactive power change And calculate the reactive power change Calculation of reactive power components VI , the formula based on is:

[0171]

[0172] It should be noted that this formula obtains the reactive power component six by comprehensively considering the changes in electrode position, resistance, inductance and current. .

[0173] Combined with the contents of step 201 to step 207:

[0174] The arc is the core part of the DC arc furnace. , can accurately capture the impact of the electrical characteristics of the arc in the furnace space on the reactive power of the entire DC arc furnace. Harmonics can cause problems such as overheating, vibration, and increased noise in electrical equipment. By calculating the reactive power component based on harmonic data, , can better assess the degree of harmonic damage to the equipment. The characteristics of the charge will change as the smelting process progresses. , DC arc furnace working voltage and charge resistance Calculation of reactive power components III , can help operators better understand the situation in the furnace and improve product quality and production efficiency. Calculate reactive power components using environmental data , we can more comprehensively understand the impact of the external environment on the reactive power of the DC arc furnace and provide a more accurate basis for the operation and maintenance of the equipment. , the effect of wind speed and wind direction on reactive power can be quantified. Reactive power components are calculated based on electrical parameter data and electrode data. , we can better understand the impact of factors such as electrode loss and position changes on reactive power.

[0175] Step 3: Based on the electrical parameter data, reactive power component 、Reactive power component 2 , reactive power component three , reactive power component 4 , reactive power component 5 and reactive power component VI Calculate reactive power forecast ; Get the current reactive power , according to the reactive power prediction value and the current reactive power Calculate reactive power change ; Preset reactive power change threshold ; According to the reactive power change value and reactive power change threshold Determine whether the working status of the DC arc furnace is normal; alarm when the working status is abnormal.

[0176] Step 301: According to the reactive power change value and reactive power change threshold The method to judge whether the working state of DC arc furnace is normal is:

[0177] According to the DC arc furnace working voltage , Working current , Power Factor , reactive power component 1 、Reactive power component 2 , reactive power component three , reactive power component 4 , reactive power component 5 and reactive power component VI Calculate reactive power forecast , the formula based on is:

[0178]

[0179] It should be noted that the operating principle of this formula is: is the basic reactive power, In order to take into account the additional impact of the interaction between various factors on reactive power, a product sum model of the interaction coefficient and the reactive power change caused by each factor is established to correct the comprehensive reactive power prediction value so that it can more accurately reflect the actual situation. This formula calculates the basic reactive power and comprehensively considers the impact of various factors on reactive power to obtain the reactive power prediction value. .

[0180] in, For the The influencing factors corresponding to the reactive power components and The interaction coefficient of the influencing factors corresponding to the reactive power components, and is the serial number corresponding to different reactive power components, ranging from 1 to 6; It is The reactive power component is , , , , and ; It is The reactive power component is , , , , and ,when When one of the numbers 1 to 6 is selected, y should be one of the other 5 numbers to ensure ,at this time is the interaction coefficient of these two reactive power components. It is determined through a large number of experiments and data analysis. The specific method is: conduct arc furnace operation tests under conditions of different combinations of factor changes, record the actual changes in reactive power, and then determine it through methods such as multiple regression analysis.

[0181] According to the reactive power prediction value and the current reactive power Calculate reactive power change , the formula based on is:

[0182]

[0183] It should be noted that the current reactive power It refers to the actual reactive power value of the DC arc furnace at the current moment, which is measured using a reactive power meter.

[0184] According to the reactive power change value and reactive power change threshold The standards for judging whether the working state of a DC arc furnace is normal are:

[0185]

[0186] It should be noted that the reactive power change threshold The method of determining the reactive power is as follows: collect historical operating data of DC arc furnace, understand the reactive power fluctuation value under normal operating conditions, and collect the 20 largest fluctuation values ​​with the smallest absolute value. Data, and calculate its average value as the reactive power change threshold Reference value.

[0187] Combined with the content of step 301:

[0188] According to the electrical parameter data, reactive power component 、Reactive power component 2 , reactive power component three , reactive power component 4 , reactive power component 5 and reactive power component VI Calculate reactive power forecast , increasing the diversity of data and solving the problem that data collection is mainly focused on the most basic electrical parameters, while insufficient data collection on some indirect factors affecting reactive power, thus affecting the accuracy of reactive power prediction. and reactive power change threshold Judging whether the working status of the DC arc furnace is normal provides staff with a specific basis for judgment, which is conducive to timely detection of problems.

[0189] On the other hand, the present invention also discloses a DC arc furnace reactive power prediction system, comprising:

[0190] Data acquisition module, used to collect electrical parameter data, arc data, harmonic data, charge data, environmental data, wind direction data and electrode data;

[0191] Calculation module, capable of calculating reactive power components based on arc data ; Calculate reactive power component 2 based on harmonic data ; Calculate the charge resistance based on charge data ; According to the phase difference after the charge characteristics , DC arc furnace working voltage and charge resistance Calculation of reactive power components III ; Calculate equivalent resistance based on electrical parameter data ; According to the equivalent resistance , electrical parameter data and environmental data to calculate temperature equivalent resistance , humidity equivalent resistance , Dust adhesion equivalent resistance and air mass equivalent resistance , and further calculate the reactive power component four ; Calculate reactive power component 5 based on wind direction data ; Calculate reactive power change based on electrical parameter data and electrode data And reactive power change , and further calculate the reactive power component six ;

[0192] The prediction module can 、Reactive power component 2 , reactive power component three , reactive power component 4 , reactive power component 5 and reactive power component VI Calculate reactive power forecast ; Get the current reactive power , according to the reactive power prediction value and the current reactive power Calculate reactive power change ; Preset reactive power change threshold ; According to the reactive power change value and reactive power change threshold Determine whether the working status of the DC arc furnace is normal; alarm when the working status is abnormal.

[0193] The above embodiments may be implemented in whole or in part by software, hardware, firmware or any other combination thereof. When implemented using software, the above embodiments may be implemented in whole or in part in the form of a computer program product. A person of ordinary skill in the art may appreciate that the units and algorithm steps of each example described in conjunction with the embodiments disclosed herein may be implemented in electronic hardware or in combination with computer software and electronic hardware. Whether these functions are performed in hardware or software depends on the specific application and design constraints of the technical solution.

[0194] The units described as separate components may or may not be physically separated, and the components shown as units may or may not be physical units, that is, they may be located in one place or distributed on multiple network units. Some or all of the units may be selected according to actual needs to achieve the purpose of the solution of this embodiment.

[0195] The above description is only a specific implementation manner of the present application, but the protection scope of the present application is not limited thereto. Any technician familiar with the technical field can easily think of changes or substitutions within the technical scope disclosed in the present application, which should be included in the protection scope of the present application.

Claims

1. A method for predicting reactive power of a DC arc furnace, characterized in that: The following steps are involved: Collect electrical parameter data, arc data, harmonic data, charge data, environmental data, wind direction data and electrode data; Calculation of reactive power components based on arc data ; Calculate reactive power component 1 The method is: Arc data including arc voltage , arc current and arc active power ; Calculate reactive power components based on arc data , the formula based on is: Calculation of reactive power components based on harmonic data II ; Calculation of reactive power component 2 The method is: Harmonic data including voltage RMS values ​​of harmonics , harmonic current effective value and phase difference ; Calculate reactive power components based on harmonic data II , the formula based on is: in, For the The effective value of the voltage of the subharmonic, is the serial number corresponding to different harmonics, and its value is ; is the number of different harmonics, which is a positive integer; For the The phase difference between subharmonic voltage and current; For the The effective value of the subharmonic current; Calculate the charge resistance based on charge data ; According to the phase difference after the charge characteristics , DC arc furnace working voltage and charge resistance Calculation of reactive power components III ; Calculate reactive power component three The method is: Charge data including charge volume fraction 、Charge resistance And the phase difference after considering the characteristics of the charge ; According to the volume fraction of the charge and charge resistance Calculate the charge resistance , the formula based on is: in, For the furnace The volume fraction of the components, is the serial number corresponding to different components, and its value is , is the total number of different components in the furnace, The value is a positive integer; For the furnace The resistance of the component; The electrical parameter data at least includes the DC arc furnace operating voltage ; According to the phase difference after considering the characteristics of the charge , DC arc furnace working voltage and charge resistance Calculation of reactive power components III , the formula based on is: Calculate equivalent resistance based on electrical parameter data , calculate the equivalent resistance The method is: The electrical parameter data also includes the initial series element resistance of the DC arc furnace and the initial parallel branch resistance ; According to the resistance of the series element and parallel branch resistance Calculate the equivalent resistance , the formula based on is: in, For the The initial resistance of the series element is is the serial number corresponding to different series elements, and its value is , is the number of series elements, which is a positive integer; For the The initial resistance of the parallel branch is is the serial number corresponding to different parallel branches, and its value is ; is the number of parallel branches; According to the equivalent resistance , electrical parameter data and environmental data to calculate temperature equivalent resistance , humidity equivalent resistance , Dust adhesion equivalent resistance and air mass equivalent resistance , and further calculate the reactive power component four ; Calculate reactive power component 4 The method is: Electrical parameter data also includes DC arc furnace operating current and working reactance ; Environmental data including operating temperature , Working humidity , Dust adhesion area and air quality index ; According to the equivalent resistance and operating temperature Calculate Temperature Equivalent Resistance , the formula based on is: in, is the temperature coefficient; is the base temperature; According to the equivalent resistance and operating humidity Calculate humidity equivalent resistance , the formula based on is: in, is the humidity coefficient; is the basic humidity; According to the equivalent resistance , dust adhesion coefficient And dust adhesion area Calculation of dust adhesion equivalent resistance , the formula based on is: in, is the dust adhesion coefficient; According to the DC arc furnace working current , equivalent resistance and air quality index Calculate the air mass equivalent resistance , the formula based on is: in, is the air quality impact coefficient; As the basic air quality index; According to the DC arc furnace working voltage , working reactance , Temperature Equivalent Resistance , humidity equivalent resistance , Dust adhesion equivalent resistance and air mass equivalent resistance , calculate the reactive power component four , the formula based on is: in, is the dielectric loss factor; Calculation of reactive power components based on wind direction data ; Calculate reactive power component five The method is: Wind direction data including wind speed , wind direction and arc angle , Phase difference when there is no wind and the current phase difference ; Calculate reactive power components based on wind direction data , the formula based on is: in, is the wind direction data influence coefficient; Calculate reactive power change based on electrical parameter data and electrode data And reactive power change , and further calculate the reactive power component six ; Calculate reactive power component six The method is: The electrical parameter data also includes the power supply angular frequency ,inductance , Power Factor and arc resistance ; Electrode data includes electrode position change , electrode current , electrode resistance and electrode inductance ; According to the DC arc furnace working voltage , power supply angular frequency ,inductance , Power Factor , electrode position change and arc resistance Calculate reactive power change , the formula based on is: in, is the arc length adjustment factor; is the electrode position adjustment coefficient; According to the DC arc furnace working current , Power Factor , electrode current , electrode resistance and electrode inductance Calculate reactive power change 2 , the formula based on is: in, is the unit time; According to the reactive power change And calculate the reactive power change Calculation of reactive power components VI , the formula based on is: According to the electrical parameter data, reactive power component 、Reactive power component 2 , reactive power component three , reactive power component 4 , reactive power component 5 and reactive power component VI Calculate reactive power forecast ; Get the current reactive power , according to the reactive power prediction value and the current reactive power Calculate reactive power change ; Preset reactive power change threshold ; According to the reactive power change value and reactive power change threshold Determine whether the DC arc furnace is working normally; alarm when the working state is abnormal; according to the reactive power change value and reactive power change threshold The method to judge whether the working state of DC arc furnace is normal is: According to the DC arc furnace working voltage , Working current , Power Factor , reactive power component 1 、Reactive power component 2 , reactive power component three , reactive power component 4 , reactive power component 5 and reactive power component VI Calculate reactive power forecast , the formula based on is: in, For the The influencing factors corresponding to the reactive power components and The interaction coefficient of the influencing factors corresponding to the reactive power components, and is the serial number corresponding to different reactive power components, ranging from 1 to 6; ; It is Reactive power component; It is Reactive power component; According to the reactive power prediction value and the current reactive power Calculate reactive power change , the formula based on is: According to the reactive power change value and reactive power change threshold The standards for judging whether the working state of a DC arc furnace is normal are: 。 2. A DC arc furnace reactive power prediction system, characterized in that: include: Data acquisition module, used to collect electrical parameter data, arc data, harmonic data, charge data, environmental data, wind direction data and electrode data; Calculation module, calculates reactive power component based on arc data ; Calculate reactive power component 1 The method is: Arc data including arc voltage , arc current and arc active power ; Calculate reactive power components based on arc data , the formula based on is: Calculation of reactive power components based on harmonic data II ; Calculation of reactive power component 2 The method is: Harmonic data including harmonic voltage RMS values , harmonic current effective value and phase difference ; Calculate reactive power components based on harmonic data II , the formula based on is: in, For the The effective value of the voltage of the subharmonic, is the serial number corresponding to different harmonics, and its value is ; is the number of different harmonics, which is a positive integer; For the The phase difference between subharmonic voltage and current; For the The effective value of the subharmonic current; Calculate the charge resistance based on charge data ; According to the phase difference after the charge characteristics , DC arc furnace working voltage and charge resistance Calculation of reactive power components III ; Calculate reactive power component three The method is: Charge data including charge volume fraction 、Charge resistance And the phase difference after considering the characteristics of the charge ; According to the volume fraction of the charge and charge resistance Calculate the charge resistance , the formula based on is: in, For the furnace The volume fraction of the components, is the serial number corresponding to different components, and its value is , is the total number of different components in the furnace, The value is a positive integer; For the furnace The resistance of the component; The electrical parameter data at least includes the DC arc furnace operating voltage ; According to the phase difference after considering the characteristics of the charge , DC arc furnace working voltage and charge resistance Calculation of reactive power components III , the formula based on is: Calculate equivalent resistance based on electrical parameter data , calculate the equivalent resistance The method is: The electrical parameter data also includes the initial series element resistance of the DC arc furnace and the initial parallel branch resistance ; According to the resistance of the series element and parallel branch resistance Calculate the equivalent resistance , the formula based on is: in, For the The initial resistance of the series element is is the serial number corresponding to different series elements, and its value is , is the number of series elements, which is a positive integer; For the The initial resistance of the parallel branch is is the serial number corresponding to different parallel branches, and its value is ; is the number of parallel branches; According to the equivalent resistance , electrical parameter data and environmental data to calculate temperature equivalent resistance , humidity equivalent resistance , Dust adhesion equivalent resistance and air mass equivalent resistance , and further calculate the reactive power component four ; Calculate reactive power component 4 The method is: Electrical parameter data also includes DC arc furnace operating current and working reactance ; Environmental data including operating temperature , Working humidity , Dust adhesion area and air quality index ; According to the equivalent resistance and operating temperature Calculate Temperature Equivalent Resistance , the formula based on is: in, is the temperature coefficient; is the base temperature; According to the equivalent resistance and operating humidity Calculating humidity equivalent resistance , the formula based on is: in, is the humidity coefficient; is the basic humidity; According to the equivalent resistance , dust adhesion coefficient and dust adhesion area Calculation of dust adhesion equivalent resistance , the formula based on is: in, is the dust adhesion coefficient; According to the DC arc furnace working current , equivalent resistance and air quality index Calculate the air mass equivalent resistance , the formula based on is: in, is the air quality impact coefficient; As the basic air quality index; According to the DC arc furnace working voltage , working reactance , Temperature Equivalent Resistance , humidity equivalent resistance , Dust adhesion equivalent resistance and air mass equivalent resistance , calculate the reactive power component four , the formula based on is: in, is the dielectric loss factor; Calculation of reactive power components based on wind direction data ; Calculate reactive power component five The method is: Wind direction data including wind speed , wind direction and arc angle , Phase difference when there is no wind and the current phase difference ; Calculate reactive power components based on wind direction data , the formula based on is: in, is the wind direction data influence coefficient; Calculate reactive power change based on electrical parameter data and electrode data And reactive power change , and further calculate the reactive power component six ; Calculate reactive power component six The method is: The electrical parameter data also includes the power supply angular frequency ,inductance , Power Factor and arc resistance ; Electrode data includes electrode position change , electrode current , electrode resistance and electrode inductance ; According to the DC arc furnace working voltage , power supply angular frequency ,inductance , Power Factor , electrode position change and arc resistance Calculate reactive power change , the formula based on is: in, is the arc length adjustment factor; is the electrode position adjustment coefficient; According to the DC arc furnace working current , Power Factor , electrode current , electrode resistance and electrode inductance Calculate reactive power change 2 , the formula based on is: in, is the unit time; According to the reactive power change And calculate the reactive power change Calculation of reactive power components VI , the formula based on is: ； The prediction module can 、Reactive power component 2 , reactive power component three , reactive power component 4 , reactive power component 5 and reactive power component VI Calculate reactive power forecast ; Get the current reactive power , according to the reactive power prediction value and the current reactive power Calculate reactive power change ; Preset reactive power change threshold ; According to the reactive power change value and reactive power change threshold Determine whether the DC arc furnace is working normally; alarm when the working state is abnormal; according to the reactive power change value and reactive power change threshold The method to judge whether the working state of DC arc furnace is normal is: According to the DC arc furnace working voltage , Working current , Power Factor , reactive power component 1 、Reactive power component 2 , reactive power component three , reactive power component 4 , reactive power component 5 and reactive power component VI Calculate reactive power forecast , the formula based on is: in, For the The influencing factors corresponding to the reactive power components and The interaction coefficient of the influencing factors corresponding to the reactive power components, and is the serial number corresponding to different reactive power components, ranging from 1 to 6; ; It is Reactive power component; It is Reactive power component; According to the reactive power prediction value and the current reactive power Calculate reactive power change , the formula based on is: According to the reactive power change value and reactive power change threshold The standards for judging whether the working state of a DC arc furnace is normal are: 。

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