Compensation impedance and reactive compensation demand capacity calculation method for short network compensation of submerged arc furnace

Abstract

The invention relates to a compensation impedance and reactive compensation demand capacity calculation method, in particular to a compensation impedance and reactive compensation demand capacity calculation method for short network compensation of a submerged arc furnace, and solves the problem that the calculation demand of reactive compensation parameters for short network compensation of the submerged arc furnace cannot be met in the prior art. The compensation impedance calculation method comprises the following steps: step 1, according to required submerged arc furnace design data and a preset compensation point position, determining a transformer secondary voltage U20, a front short network current I20, a power factor cosphi0, a front short network loop total inductive reactance XLb and a power factor cosphi1 in a standard compensation working state in a standard natural working state; 2, basic parameters are calculated, specifically, 2.1, the short network loop total inductive reactance XL and the short network loop total resistance R in the standard natural working state are calculated; step 2.2, calculating an inductive reactance ratio kL of the front short network; and step 3, calculating to obtain equivalent compensation impedance Xc0 of each phase.

Description

Technical Field

[0001] The invention relates to a method for calculating compensation impedance and reactive power compensation demand capacity, and in particular to a method for calculating compensation impedance and reactive power compensation demand capacity of short-circuit compensation of an ore-fired furnace. Background Art

[0002] The existing reactive power compensation required capacity calculation formula is shown in formula [1]:

[0003]

[0004] In formula [1]: Q′ X represents the reactive power compensation capacity per phase calculated by the existing reactive power compensation capacity calculation formula, i.e., formula [1]; P represents the active power of the system; Indicates the power factor under standard natural working conditions The corresponding tangent of the power angle; Indicates the power factor under standard compensation working condition The tangent value of the corresponding power angle. The above formula [1] is a simplified calculation formula. The premise of its simplification is that the load impedance is much larger than the line impedance. After the reactive power compensation equipment is put into operation, the voltage at the compensation point and the active power of the load are very small; the above compensation point refers to the access point where the reactive power compensation equipment on the short-circuit network is connected to the short-circuit network. In addition, since the load impedance is much larger than the line impedance in most cases, the compensation impedance is not considered when performing reactive power compensation in the prior art, which leads to the fact that there is no calculation formula for calculating the compensation impedance in the prior art.

[0005] However, for the short-circuit compensation of the submerged arc furnace, since the internal impedance of the submerged arc furnace is in the milliohm level, the short-circuit impedance of the submerged arc furnace, especially the inductive reactance of the short-circuit loop, is at the same order of magnitude as the internal impedance of the submerged arc furnace and the total impedance of the short-circuit loop. After the reactive power compensation equipment is put into operation, it will have a great impact on the voltage at the compensation point and the active power of the load, causing them to change to a certain extent, and does not meet the prerequisite for simplifying the above formula [1]. Therefore, the above formula [1] is not suitable for the calculation of the reactive power compensation demand capacity of the short-circuit compensation of the submerged arc furnace. At the same time, since the short-circuit impedance of the submerged arc furnace, especially the inductive reactance of the short-circuit loop, is at the same order of magnitude as the internal impedance of the submerged arc furnace and the total impedance of the short-circuit loop, it is necessary to consider the compensation impedance in the short-circuit compensation of the submerged arc furnace, and then calculate the compensation impedance. However, as can be seen from the above, there is no calculation formula for calculating the compensation impedance in the prior art.

[0006] In summary, the existing technology cannot meet the calculation requirements of reactive compensation parameters for short-circuit compensation of electric arc furnaces. Summary of the invention

[0007] The purpose of the present invention is to solve the technical problem that the prior art cannot meet the calculation requirements of reactive compensation parameters of short-circuit compensation of an ore-fired furnace, and to provide a method for calculating the compensation impedance and reactive compensation demand capacity of short-circuit compensation of an ore-fired furnace.

[0008] In order to solve the above technical problems, the technical solution adopted by the present invention is:

[0009] A method for calculating compensation impedance of short-circuit compensation of an electric arc furnace is special in that it includes the following steps:

[0010] Step 1: Determine the basic design data of the short network compensation of the submerged arc furnace according to the required submerged arc furnace design data and the position of the preset compensation point;

[0011] The compensation point refers to the access point where the reactive compensation equipment on the short network is connected to the short network; the short network is divided into two sections, the front short network and the rear short network, through the compensation point, wherein the front short network is the short network between the transformer and the compensation point, and the rear short network is the short network between the compensation point and the electrode;

[0012] The basic design data of the short-circuit compensation of the submerged arc furnace include the basic standard operation data of the submerged arc furnace under the standard natural working state, the total inductive reactance XLb of the front short-circuit circuit, and the basic standard operation data of the submerged arc furnace under the standard compensation working state;

[0013] The standard natural working state refers to the standard working state of the ore-heating furnace when the reactive power compensation equipment is not put into use; the basic standard operating data of the ore-heating furnace under the standard natural working state include the transformer secondary voltage U 20 , front short-circuit current I 20 And power factor

[0014] The total inductive reactance XLb of the front short-circuit network loop is the total inductive reactance equivalent to the transformer inductive reactance and the front short-circuit network loop inductive reactance to the secondary side of the transformer;

[0015] The standard compensation working state refers to the standard working state of the ore-heating furnace when the reactive power compensation equipment is put into use; the basic standard operating data of the ore-heating furnace under the standard compensation working state include the power factor under the standard compensation working state.

[0016] Step 2: According to the basic design data of short-circuit compensation of submerged arc furnace determined in step 1, calculate the basic parameters, including:

[0017] Step 2.1: According to the transformer secondary voltage U under the standard natural working state determined in step 1 20 , front short-circuit current I 20 And power factor Calculate the total inductive reactance XL of the short-circuit circuit and the total resistance R of the short-circuit circuit under the standard natural working state; the total inductive reactance XL of the short-circuit circuit is the total inductive reactance including the circuit inductive reactance of the front short-circuit circuit and the rear short-circuit circuit and the inductive reactance in the furnace; the total resistance R of the short-circuit circuit is the total resistance including the circuit resistance of the front short-circuit circuit and the rear short-circuit circuit and the resistance in the furnace;

[0018] Step 2.2: Calculate the proportion of the total inductive reactance XLb of the front short-circuit circuit determined in step 1 to the total inductive reactance XL of the short-circuit circuit under the standard natural working state calculated in step 2.1, that is, the proportion of the inductive reactance of the front short-circuit circuit kL;

[0019] Step 3: Compensate the power factor under working condition according to the standard determined in step 1 The total inductive reactance XL and total resistance R of the short-circuit circuit under the standard natural working state calculated in step 2, as well as the proportion of the front short-circuit inductive reactance kL, are used to calculate the equivalent compensation impedance Xc0 of each phase, thus completing the compensation impedance calculation.

[0020] Furthermore, in step 2.1, when calculating the total inductive reactance XL of the short-circuit circuit under the standard natural working state, formula [2] is used for calculation, and the formula [2] is:

[0021]

[0022] When calculating the total resistance R of the short-circuit circuit under the standard natural working state, the formula [3] is used for calculation, and the formula [3] is:

[0023]

[0024] Furthermore, in step 3, when calculating the equivalent compensation impedance Xc0 of each phase, formula [5] is used for calculation, and the formula [5] is:

[0025]

[0026] In formula [5]: A represents the compensation impedance factor, which is calculated using formula [5-1]; B represents the compensation impedance position influence factor, which is calculated using formula [5-2];

[0027] The formula [5-1] is:

[0028]

[0029] In formula [5-1]: Indicates the power factor under standard compensation working condition The corresponding tangent value of the power angle is calculated using formula [5-1-1]:

[0030] The formula [5-1-1] is:

[0031]

[0032] The formula [5-2] is:

[0033]

[0034] Furthermore, in order to improve the active power of the ore-fired furnace while preventing the voltage from fluctuating too much, the preset compensation point is located between the transformer and the electrode on the short-circuit grid.

[0035] At the same time, the present invention also provides a method for calculating the reactive compensation demand capacity of short-circuit compensation of an ore-fired furnace, which is special in that it includes the following steps:

[0036] Step A: adopt the compensation impedance calculation method for short-circuit compensation of an ore-fired furnace as described in any one of claims 1 to 4 to calculate and obtain the equivalent compensation impedance Xc0 of each phase; at the same time, according to the required ore-fired furnace design data and the position of the preset compensation point, determine the total active power P under the standard compensation working state 21 And the front short-circuit current I 21 ;

[0037] Step B: Based on the equivalent compensation impedance Xc0 of each phase obtained by calculation in step A, the total active power P under the standard compensation working state determined in step 1 21 , front short-circuit current I 21 and power factor The total short-circuit inductive reactance XL under the standard natural working state calculated in step 2.1 and the proportion of the short-circuit inductive reactance kL calculated in step 2.2 are used to calculate the reactive compensation demand capacity Q for each phase. x , complete the calculation of reactive compensation demand capacity for short-circuit compensation of electric arc furnace.

[0038] Furthermore, in step B, the reactive power compensation required capacity Q of each phase is calculated. x When , the calculation is performed using formula [6], which is:

[0039]

[0040] In formula [6]: U c Represents the voltage between the busbar of the reactive power compensation equipment and the short-circuit connection point, calculated using formula [6-1];

[0041] The formula [6-1] is:

[0042]

[0043] In formula [6-1]: U 21 It represents the transformer secondary output voltage under the standard compensation working state, and is calculated using formula [6-1-1];

[0044] The formula [6-1-1] is:

[0045]

[0046] In formula [6-1-1]: S 21 It represents the total apparent power of the ore-fired furnace system and is calculated using formula [6-1-1-1];

[0047] The formula [6-1-1-1] is:

[0048]

[0049] The beneficial effects of the present invention are:

[0050] (1) The compensation impedance calculation method of the short-circuit compensation of the submerged arc furnace and the reactive compensation demand capacity calculation method of the short-circuit compensation of the submerged arc furnace in the present invention are aimed at the short-circuit compensation of the submerged arc furnace. The internal impedance of the submerged arc furnace is in the milliohm level. The short-circuit impedance of the submerged arc furnace, especially the inductive reactance of the short-circuit loop, is in the same order of magnitude as the internal impedance of the submerged arc furnace and the total impedance of the short-circuit loop. After the reactive compensation equipment is put into operation, it will have a great impact on the voltage at the compensation point and the active power of the load, causing them to change to a certain extent. In the calculation process, the position of the compensation point is used to calculate the equivalent compensation impedance Xc0 of each phase and the reactive compensation demand capacity Q of each phase. x Taking into account the influence of x They are all related to the position of the compensation point. When the compensation point is located at different positions, the calculated equivalent compensation impedance Xc0 of each phase and the reactive compensation required capacity Q of each phase are x Different, therefore, the method of the present invention can achieve more accurate calculation of the compensation impedance and reactive compensation required capacity of the corresponding short-circuit compensation of the submerged arc furnace when the compensation point is located at different positions; therefore, the present invention solves the technical problem that the prior art cannot meet the calculation requirements of the reactive compensation parameters of the short-circuit compensation of the submerged arc furnace. According to the equivalent compensation impedance Xc0 of each phase and the reactive compensation required capacity Q of each phase calculated by the method of the present invention x , compensation at the corresponding compensation point is more conducive to improving the overall production efficiency and electricity energy efficiency of the ore-fired furnace.

[0051] (2) In the present invention, when calculating the reactive compensation demand capacity of the short-network compensation of the electric arc furnace, the influence of the compensation impedance on the reactive compensation demand capacity of the short-network compensation of the electric arc furnace is taken into account, and the calculation result is more accurate. In addition, the present invention provides a method for calculating the compensation impedance of the short-network compensation of the electric arc furnace. BRIEF DESCRIPTION OF THE DRAWINGS

[0052] Figure 1It is a flow chart of an embodiment of a method for calculating compensation impedance of short-circuit compensation of a submerged arc furnace according to the present invention;

[0053] Figure 2 The present invention is a flowchart of an embodiment of a method for calculating reactive compensation demand capacity of short-circuit compensation of an electric arc furnace. DETAILED DESCRIPTION

[0054] The present invention is described in detail below with reference to the accompanying drawings and specific embodiments.

[0055] See also Figure 1 The present invention provides a method for calculating the compensation impedance of a short network compensation of an electric arc furnace, comprising the following steps:

[0056] Step 1: Determine the basic design data of the short network compensation of the submerged arc furnace according to the required submerged arc furnace design data and the position of the preset compensation point;

[0057] The compensation point refers to the access point where the reactive power compensation device on the short network is connected to the short network; the short network is divided into two sections, the front short network and the rear short network, through the compensation point, wherein the front short network is the short network between the transformer and the compensation point, and the rear short network is the short network between the compensation point and the electrode; for the ore-fired furnace, it is generally not recommended to set the compensation point close to the electrode side; in order to both improve the active power of the ore-fired furnace and avoid excessive voltage fluctuations, the preset compensation point is preferably located between the transformer and the electrode on the short network;

[0058] The basic design data of the short-circuit compensation of the above-mentioned submerged arc furnace include the basic standard operation data of the submerged arc furnace under the standard natural working state, the total inductive reactance XLb of the front short-circuit circuit, and the basic standard operation data of the submerged arc furnace under the standard compensation working state;

[0059] The above standard natural working state refers to the standard working state of the ore-heating furnace when the reactive power compensation equipment is not put into use; the basic standard operating data of the ore-heating furnace under the above standard natural working state include the transformer secondary voltage U under the standard natural working state 20 , front short-circuit current I 20 And power factor Transformer secondary voltage U under standard natural working conditions 20 The unit is V, the front short-circuit current I under the standard natural working state 20 The unit is kA;

[0060] The total inductive reactance XLb of the front short-circuit network loop is the total inductive reactance of the transformer and the front short-circuit network loop equivalent to the secondary side of the transformer;

[0061] The above standard compensation working state refers to the standard working state of the ore-heating furnace when the reactive power compensation equipment is put into use; the basic standard operating data of the ore-heating furnace under the above standard compensation working state include the power factor under the standard compensation working state

[0062] Step 2: According to the basic design data of short-circuit compensation of submerged arc furnace determined in step 1, calculate the basic parameters, including:

[0063] Step 2.1: According to the transformer secondary voltage U under the standard natural working state determined in step 1 20 , front short-circuit current I 20 And power factor Calculate the total inductive reactance XL of the short-circuit circuit and the total resistance R of the short-circuit circuit under the standard natural working state; the total inductive reactance XL of the short-circuit circuit is the total inductive reactance including the circuit inductive reactance of the front short-circuit circuit and the rear short-circuit circuit and the inductive reactance in the furnace; the total resistance R of the short-circuit circuit is the total resistance including the circuit resistance of the front short-circuit circuit and the rear short-circuit circuit and the resistance in the furnace;

[0064] In this embodiment, in step 2.1, when calculating the total inductive reactance XL of the short-circuit circuit under the standard natural working state, formula [2] is used for calculation, and the above formula [2] is:

[0065]

[0066] The unit of the total inductive reactance XL of the short-circuit circuit under the above standard natural working state is mΩ;

[0067] When calculating the total resistance R of the short-circuit circuit under the standard natural working state, the formula [3] is used for calculation. The above formula [3] is:

[0068]

[0069] The unit of the total resistance R of the short-circuit loop under the above standard natural working state is mΩ;

[0070] Step 2.2: Calculate the ratio of the total inductive reactance XLb of the short-circuit circuit determined in step 1 to the total inductive reactance XL of the short-circuit circuit under the standard natural working state calculated in step 2.1, that is, the ratio of the inductive reactance of the short-circuit circuit kL, and the calculation formula is shown in formula [4]:

[0071]

[0072] Step 3: Compensate the power factor under working condition according to the standard determined in step 1 The total inductive reactance XL and total resistance R of the short-circuit circuit under the standard natural working state calculated in step 2, as well as the proportion of the front short-circuit inductive reactance kL, are used to calculate the equivalent compensation impedance Xc0 of each phase, thus completing the compensation impedance calculation.

[0073] In this embodiment, in step 3, when calculating the equivalent compensation impedance Xc0 of each phase, formula [5] is used for calculation, and the above formula [5] is:

[0074]

[0075] In formula [5]: A represents the compensation impedance factor, which is calculated using formula [5-1]; B represents the compensation impedance position influence factor, which is calculated using formula [5-2];

[0076] The above formula [5-1] is:

[0077]

[0078] In formula [5-1]: Indicates the power factor under standard compensation working condition The corresponding tangent value of the power angle is calculated using formula [5-1-1]:

[0079] The above formula [5-1-1] is:

[0080]

[0081] The above formula [5-2] is:

[0082]

[0083] The calculated equivalent compensation impedance Xc0 of each phase is the total impedance of all capacitors, busbars and series reactances of each phase of the reactive compensation equipment, and its unit is mΩ.

[0084] Also, see Figure 2 The present invention also provides a method for calculating the reactive compensation demand capacity of short-circuit compensation of an electric arc furnace, comprising the following steps:

[0085] Step A: Use the above-mentioned compensation impedance calculation method for short-circuit compensation of the submerged arc furnace to calculate and obtain the equivalent compensation impedance Xc0 of each phase; at the same time, according to the required submerged arc furnace design data and the position of the preset compensation point, determine the total active power P under the standard compensation working state 21 And the front short-circuit current I 21 ; The total active power P under the above standard compensation working state 21 The unit is kW, the front short-circuit current I under standard compensation working condition 21 The unit is kA;

[0086] Step B: Based on the equivalent compensation impedance Xc0 of each phase obtained by calculation in step A, the total active power P under the standard compensation working state determined in step 1 21 , front short-circuit current I 21and power factor The total short-circuit inductive reactance XL under the standard natural working state calculated in step 2.1 and the proportion of the short-circuit inductive reactance kL calculated in step 2.2 are used to calculate the reactive compensation demand capacity Q for each phase. x , complete the calculation of reactive compensation demand capacity for short-circuit compensation of electric arc furnace.

[0087] In this embodiment, in step B, the reactive power compensation required capacity Q of each phase is calculated. x When , the formula [6] is used for calculation, and the above formula [6] is:

[0088]

[0089] In formula [6]: U c It represents the voltage between the busbar of the reactive power compensation equipment and the short-circuit connection point, in V, calculated using formula [6-1];

[0090] The above formula [6-1] is:

[0091]

[0092] In formula [6-1]: U 21 It represents the transformer secondary output voltage under standard compensation working condition, in V, calculated using formula [6-1-1];

[0093] The above formula [6-1-1] is:

[0094]

[0095] In formula [6-1-1]: S 21 It represents the total apparent power of the ore-fired furnace system in kVA, and is calculated using formula [6-1-1-1];

[0096] The above formula [6-1-1-1] is:

[0097]

[0098] The calculated reactive power compensation requirement capacity Q for each phase x The unit is kVar.

[0099] In summary, the method of the present invention can achieve more accurate calculation of the compensation impedance and reactive compensation demand capacity of the corresponding short-circuit compensation of the ore-fired furnace when the compensation point is located at different positions; the equivalent compensation impedance Xc0 of each phase and the reactive compensation demand capacity Q of each phase calculated by the method can be calculated by the method of the present invention. x , compensation at the corresponding compensation point is more conducive to improving the overall production efficiency and electricity energy efficiency of the ore-fired furnace.

Claims

1. A method for calculating the compensation impedance of short-circuit compensation of an electric arc furnace, characterized in that: The following steps are involved: Step 1: Determine the basic design data of the short network compensation of the submerged arc furnace according to the required submerged arc furnace design data and the position of the preset compensation point; The compensation point refers to the access point where the reactive power compensation equipment on the short circuit network is connected to the short circuit network; The short network is divided into two sections, a front short network and a rear short network, through the compensation point, wherein the front short network is the short network between the transformer and the compensation point, and the rear short network is the short network between the compensation point and the electrode; The basic design data of the short-circuit compensation of the submerged arc furnace include the basic standard operation data of the submerged arc furnace under the standard natural working state, the total inductive reactance XLb of the front short-circuit circuit, and the basic standard operation data of the submerged arc furnace under the standard compensation working state; The standard natural working state refers to the standard working state of the ore-heating furnace when the reactive power compensation equipment is not put into use; the basic standard operating data of the ore-heating furnace under the standard natural working state include the transformer secondary voltage U 20 , front short-circuit current I 20 And power factor The total inductive reactance XLb of the front short-circuit network loop is the total inductive reactance equivalent to the transformer inductive reactance and the front short-circuit network loop inductive reactance to the secondary side of the transformer; The standard compensation working state refers to the standard working state of the ore-heating furnace when the reactive power compensation equipment is put into use; the basic standard operating data of the ore-heating furnace under the standard compensation working state include the power factor under the standard compensation working state. Step 2: According to the basic design data of short-circuit compensation of submerged arc furnace determined in step 1, calculate the basic parameters, including: Step 2.1: According to the transformer secondary voltage U under the standard natural working state determined in step 1 20 , front short-circuit current I 20 And power factor Calculate the total inductive reactance XL of the short-circuit circuit and the total resistance R of the short-circuit circuit under the standard natural working state; the total inductive reactance XL of the short-circuit circuit is the total inductive reactance including the circuit inductive reactance of the front short-circuit circuit and the rear short-circuit circuit and the inductive reactance in the furnace; the total resistance R of the short-circuit circuit is the total resistance including the circuit resistance of the front short-circuit circuit and the rear short-circuit circuit and the resistance in the furnace; Step 2.2: Calculate the proportion of the total inductive reactance XLb of the front short-circuit circuit determined in step 1 to the total inductive reactance XL of the short-circuit circuit under the standard natural working state calculated in step 2.1, that is, the proportion of the inductive reactance of the front short-circuit circuit kL; Step 3: Compensate the power factor under working condition according to the standard determined in step 1 The total inductive reactance XL and total resistance R of the short-circuit circuit under the standard natural working state calculated in step 2, as well as the proportion of the front short-circuit inductive reactance kL, are used to calculate the equivalent compensation impedance Xc0 of each phase, thus completing the compensation impedance calculation.

2. The method for calculating the compensation impedance of short-circuit compensation of a submerged arc furnace according to claim 1, characterized in that: In step 2.1, when calculating the total inductive reactance XL of the short-circuit circuit under the standard natural working state, formula [2] is used for calculation, and the formula [2] is: When calculating the total resistance R of the short-circuit circuit under the standard natural working state, the formula [3] is used for calculation, and the formula [3] is:

3. The method for calculating the compensation impedance of short-circuit compensation of a submerged arc furnace according to claim 2, characterized in that: In step 3, when calculating the equivalent compensation impedance Xc0 of each phase, formula [5] is used for calculation, and the formula [5] is: In formula [5]: A represents the compensation impedance factor, which is calculated using formula [5-1]; B represents the compensation impedance position influence factor, which is calculated using formula [5-2]; The formula [5-1] is: In formula [5-1]: Indicates the power factor under standard compensation working condition The corresponding tangent value of the power angle is calculated using formula [5-1-1]: The formula [5-1-1] is: The formula [5-2] is:

4. The method for calculating the compensation impedance of the short network compensation of the submerged arc furnace according to any one of claims 1 to 3, characterized in that: The preset compensation point is located between the transformer and the electrode on the short circuit network.

5. A method for calculating the reactive compensation demand capacity of short-circuit compensation of a submerged arc furnace, characterized in that: The following steps are involved: Step A: adopt the compensation impedance calculation method for short-circuit compensation of an ore-fired furnace as described in any one of claims 1 to 4 to calculate and obtain the equivalent compensation impedance Xc0 of each phase; at the same time, according to the required ore-fired furnace design data and the position of the preset compensation point, determine the total active power P under the standard compensation working state 21 And the front short-circuit current I 21 ; Step B: Based on the equivalent compensation impedance Xc0 of each phase obtained by calculation in step A, the total active power P under the standard compensation working state determined in step 1 21 , front short-circuit current I 21 and power factor The total short-circuit inductive reactance XL under the standard natural working state calculated in step 2.1 and the proportion of the short-circuit inductive reactance kL calculated in step 2.2 are used to calculate the reactive compensation demand capacity Q for each phase. x , complete the calculation of reactive compensation demand capacity for short-circuit compensation of electric arc furnace.

6. The method for calculating the reactive compensation required capacity of short-circuit compensation of a submerged arc furnace according to claim 5, characterized in that: In step B, calculate the reactive power compensation required capacity Q for each phase x When , the calculation is performed using formula [6], which is: In formula [6]: U c Represents the voltage between the busbar of the reactive power compensation equipment and the short-circuit connection point, calculated using formula [6-1]; The formula [6-1] is: In formula [6-1]: U 21 It represents the transformer secondary output voltage under the standard compensation working state, and is calculated using formula [6-1-1]; The formula [6-1-1] is: In formula [6-1-1]: S 21 It represents the total apparent power of the ore-fired furnace system and is calculated using formula [6-1-1-1]; The formula [6-1-1-1] is:

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