Method for solving ground wire current of mining cable
A method for accurately predicting mining cable grounding wire currents through core current measurements and mathematical modeling addresses inefficiencies in existing methods, enhancing fault detection and network protection.
Patent Information
- Application Number
- CN202411494050.X
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2024-10-24
- Publication Date
- 2024-12-27
AI Technical Summary
Existing methods for analyzing the current characteristics of mining cable grounding wires in harsh mine environments are inefficient and costly, often leading to equipment overheating, grounding faults, and fires due to unclear signal characteristics and high calculation complexity.
A method involving measuring core currents, calculating mutual inductance and capacitance voltages, and determining current attenuation factors to establish a mathematical model for predicting grounding wire currents accurately, enabling real-time monitoring and analysis.
The method provides high accuracy in steady-state current analysis, facilitating effective fault detection and protection of underground distribution networks.
Smart Images
Figure CN119199245A_ABST
Abstract
Description
Technical Field
[0001] The invention relates to the field of mining cables, in particular to a method for solving the current of a mining cable grounding wire. Background Art
[0002] Due to the complex and changeable environment of mines, such as high humidity, large temperature changes, and harmful gases, the current characteristics of the cable grounding wire are significantly different from those of the ground environment, which makes it more important to solve the current of the cable grounding wire in mines. Abnormal changes in the current of the cable grounding wire may cause serious consequences such as equipment overheating, grounding faults, and even fires. Therefore, accurately solving the current of the mine cable grounding wire can not only effectively warn of potential safety hazards, but also provide a basis for fault line selection analysis.
[0003] At present, the methods for selecting fault lines for mining cables can be roughly divided into two types: those based on injection signals and those based on fault information. Among them, the line selection method based on fault information can be further divided into steady-state information method and transient information method. The line selection method based on injection signals relies on expensive equipment, and the line selection cost is high. In addition, the harsh environment of the mine may make the injection signal characteristics unclear, making it difficult to analyze the characteristics of the distribution network line fault situation; the steady-state information method is mostly applicable to a single specific working condition and is easily affected by the transition resistance, making it difficult to analyze the characteristics of the distribution network line fault situation through the grounding wire current; the transient information method is prone to the characteristics of the transient signal being unclear. Although the reliability is improved after adding the improved algorithm, the calculation amount is increased, and the characteristics of the distribution network line situation become complicated. By establishing a mathematical model of the cable system and combining it with the actual working conditions of the mine, the grounding wire current can be predicted more accurately. Therefore, based on the model analysis, a fast and effective cable grounding wire current solution method can be studied to realize the real-time monitoring and analysis of the mine cable grounding wire current, which has important practical significance for the analysis of underground distribution network line faults. Summary of the invention
[0004] The technical problem to be solved by the present invention is to provide a method for solving the current of a mine cable grounding wire in order to solve the steady-state current expression of a mine mobile cable grounding wire more conveniently and quickly in view of the deficiencies of the above-mentioned prior art.
[0005] In order to solve the above technical problems, the technical solution adopted by the present invention is:
[0006] A method for solving the current of a mine cable grounding wire comprises the following steps:
[0007] S1. Measure the core current at the beginning of the cable Where i = A, B, C, representing phase A, phase B, and phase C respectively. Respectively represent the i-phase core current at the beginning of the cable; and obtain the cable grounding wire resistance, the mutual resistance and mutual inductance between the cable core and the shielding layer, and the cable length;
[0008] S2. Calculate the voltage V generated by the mutual inductance and mutual capacitance of the power core D and the control core E to any shielding layer or grounding core K flowing through the grounding loop. R_G (t);
[0009] S3. Calculate the voltage V generated by the mutual inductance and mutual capacitance between the three-phase wire cores A, B, and C and the shielding layer. ABC (t);
[0010] S4. Calculate the ground wire current attenuation factor α in the absence of faults;
[0011] S5. Calculate the characteristic components of the grounding wire current in the absence of faults
[0012] S6. Based on steps S4 and S5, find the current expression of the connecting wire in the case of no fault.
[0013] S7. Based on the grounding wire current solved in S6, the steady-state grounding wire current expression is obtained by taking the limit.
[0014] As a further preferred embodiment of the present invention, it also includes S8. When a line fault occurs, based on steps S2, S3, S4, S5, S6 and S7, the steady-state current expression of the fault line grounding line and the steady-state current expression of the non-fault line grounding line under the fault condition are solved.
[0015] As a further preferred embodiment of the present invention, in S2, the sum of the mutual inductive reactance and mutual capacitive reactance voltage V generated between the power core D and the control core E to the shielding layer or the grounding core is calculated. R_G (t):
[0016]
[0017] Among them, R AM is the mutual inductance resistance, L AM Mutual inductance reactance, l is the cable length, is the voltage of the power core and the control core at the beginning of the line. The current of the power core and the control core at the beginning of the line. is the voltage at the beginning of the grounding core, C AM is the mutual capacitance between the cables.
[0018] As a further preferred embodiment of the present invention, in S3, the sum of the mutual inductive reactance and mutual capacitive reactance voltage V generated between the three-phase cores A, B, and C and the shielding layer is calculated. ABC (t):
[0019]
[0020] in, is the voltage at the beginning of each phase core, It is the shielding voltage at the beginning of each phase core.
[0021] As a further preferred embodiment of the present invention, in S4, the ground wire current attenuation factor α is calculated in the absence of a fault:
[0022]
[0023] Among them, Rg is the grounding resistance.
[0024] As a further preferred embodiment of the present invention, in S5, the characteristic component of the grounding wire current under the condition of no fault is obtained.
[0025] As a further preferred embodiment of the present invention, in S6, the ground wire current is obtained based on steps S4 and S5. The expression is as follows:
[0026]
[0027] Where C1 is a constant.
[0028] As a further preferred embodiment of the present invention, in S7, by taking the limit, the grounding wire current after stabilization is obtained. The expression is as follows:
[0029]
[0030] As a further preferred embodiment of the present invention, in S8, the expression of the ground wire current after stabilization is obtained as follows:
[0031] In the case of a fault, the zero-sequence current of the fault-free line affects V 0sumW (t) is expressed as follows:
[0032]
[0033] in, is the sum of the three-phase currents of the fault-free line, is the i-phase current of the fault-free line, i = A, B, C;
[0034] In the case of a fault, the sum of the currents of the power core and control core of the fault-free line is V DEW (t) is expressed as follows:
[0035]
[0036] in, is the power core and control core current of the fault-free line, p = D, E;
[0037] In the event of a fault, after the current of the fault-free grounding wire stabilizes The expression is as follows:
[0038]
[0039] Among them, α is the attenuation factor;
[0040] In the case of a fault, the zero-sequence current of the fault line affects V 0sumf (t) is expressed as follows:
[0041]
[0042] in, is the sum of the three-phase currents of the fault line, is the i-phase current of the fault line, i = A, B, C, x is the fault distance;
[0043] In the case of a fault, the sum of the currents of the power core and control core of the fault line V DEf (t) is expressed as follows:
[0044]
[0045] in, is the power core and control core current of the fault line, p = D, E;
[0046] In the event of a fault, after the fault grounding current stabilizes The expression is as follows:
[0047]
[0048] The present invention has the following beneficial effects:
[0049] The invention is suitable for solving the steady-state current of the grounding wire of a mobile cable for mining, has high calculation accuracy, and can perform cable fault analysis through the grounding wire current, which is beneficial for analyzing the fault conditions of underground cables and can better protect the underground distribution network cables, and has good engineering practice value. BRIEF DESCRIPTION OF THE DRAWINGS
[0050] Figure 1 It is a flow chart of the present invention;
[0051] Figure 2 Schematic diagram of the structure of six-core mining cable;
[0052] Figure 3 Schematic diagram of the concentrated parameter model of six-core mining cable.
[0053] in: is the current at the beginning of the i-phase core, is the current at the beginning of the i-phase line core, where i = A, B, C, is the current at the beginning of the shield layer of the i-phase line core, is the current at the end of the shield layer of the i-phase line core, where i = A, B, C, is the current at the beginning of the p-phase core, is the current at the end of the p-phase core, where p = D, E, F, is the voltage at the beginning of the i-phase line core, is the voltage at the end of the i-phase core, where i = A, B, C, is the voltage at the beginning of the shield layer of the i-phase line core, is the voltage at the end of the shield layer of the i-phase line core, where i = A, B, C, is the voltage at the beginning of the p-phase line core, where p = D, E, F, y AM is the mutual capacitance, z AM is the mutual inductance and y AM =C AM , z AM =RAM+jL AM , where j is an imaginary unit, Rg is the grounding resistance, is the first-end ground wire current, is the end grounding line current, x is the fault distance, and L is the line length. DETAILED DESCRIPTION
[0054] The present invention will be further described in detail below in conjunction with the accompanying drawings and specific preferred embodiments.
[0055] like Figure 1-3 As shown, the present invention discloses a method for solving the current of a mining cable grounding wire, comprising the following steps:
[0056] S1. Measure the core current at the beginning of the cable Where i = A, B, C, representing phase A, phase B, and phase C respectively. Represent the i-phase core current at the beginning of the cable. Obtain the cable grounding wire resistance, the mutual resistance and mutual inductance between the cable core and the shielding layer, and the cable length.
[0057] S2. Calculate the voltage V generated by the mutual inductance and mutual capacitance of the power core D and the control core E to any shielding layer (or grounding core K) flowing through the grounding loop. R_G (t).V R_G The expression of (t) is as follows:
[0058]
[0059] Among them, R AM is the mutual inductance resistance, LAM Mutual inductance reactance, l is the cable length, is the voltage of the power core and the control core at the beginning of the line. The current of the power core and the control core at the beginning of the line. is the voltage at the beginning of the grounding core, C AM is the mutual capacitance between the cables.
[0060] S3. Calculate the voltage V generated by the mutual inductance and mutual capacitance between the three-phase wire cores A, B, and C and the shielding layer. ABC (t).V ABC The expression of (t) is as follows:
[0061]
[0062] in, is the voltage at the beginning of each phase core, It is the shielding voltage at the beginning of each phase core.
[0063] S4. Calculate the ground wire current attenuation factor α under the condition of no fault. The expression of α is as follows:
[0064]
[0065] Among them, Rg is the grounding resistance.
[0066] S5. Calculate the characteristic components of the grounding wire current in the absence of faults The expression is as follows:
[0067]
[0068] S6. Based on steps S4 and S5, find the current expression of the connecting wire in the case of no fault. The expression is as follows:
[0069]
[0070] Where C1 is a constant.
[0071] S7. Based on the ground wire current solved in step S6, a steady-state ground wire current expression is obtained by taking the limit. The expression is as follows:
[0072]
[0073] S8. When a line fault occurs, based on S2, S3, S4, S5, S6 and S7, solve the steady-state current expression of the fault line grounding and the steady-state current expression of the non-fault line grounding line under fault conditions. The stable grounding line current expression is as follows:
[0074] ① In the case of a fault, the zero-sequence current of the fault-free line affects V 0sumW (t) is expressed as follows:
[0075]
[0076] in, is the sum of the three-phase currents of the fault-free line, is the i-phase current of the fault-free line, i=A, B, C.
[0077] ② In the case of a fault, the sum of the currents of the power core and control core of the fault-free line is V DEW (t) is expressed as follows:
[0078]
[0079] in, are the power core and control core currents of the fault-free line, p=D, E.
[0080] ③ In the case of a fault, after the current of the fault-free grounding wire stabilizes The expression is as follows:
[0081]
[0082] Among them, α is the attenuation factor.
[0083] ④ In the case of a fault, the zero-sequence current of the fault line affects V 0sumf (t) is expressed as follows:
[0084]
[0085] in, is the sum of the three-phase currents of the fault line, is the i-phase current of the fault line, i=A, B, C, and x is the fault distance.
[0086] ⑤ In the case of a fault, the sum of the currents of the power core and control core of the fault line V DEf (t) is expressed as follows:
[0087]
[0088] in, are the power core and control core currents of the fault line, p=D, E.
[0089] ⑥ In the event of a fault, after the fault grounding wire current stabilizes The expression is as follows:
[0090]
[0091] The present invention is suitable for solving the steady-state current of the grounding wire of a mobile cable for mining, and has high calculation accuracy. The cable fault analysis is performed through the grounding wire current, which is conducive to analyzing the fault condition of the underground cable, and can better protect the underground distribution network cable, and has good engineering practice value. Based on the model analysis, a fast and effective cable grounding wire current solution method is studied, which can realize the real-time monitoring and analysis of the mining cable grounding wire current, and has important practical significance for the line fault analysis of the underground distribution network.
[0092] The preferred embodiments of the present invention are described in detail above; however, the present invention is not limited to the specific details in the above embodiments. Within the technical concept of the present invention, various equivalent transformations can be made to the technical solutions of the present invention, and these equivalent transformations all belong to the protection scope of the present invention.
Claims
1. A method for calculating the current of a mine cable grounding wire, characterized in that: The following steps are involved: S1. Measure the core current at the beginning of the cable Where i = A, B, C, representing phase A, phase B, and phase C respectively. Respectively represent the i-phase core current at the beginning of the cable; and obtain the cable grounding wire resistance, the mutual resistance and mutual inductance between the cable core and the shielding layer, and the cable length; S2. Calculate the voltage V generated by the mutual inductance and mutual capacitance of the power core D and the control core E to any shielding layer or grounding core K flowing through the grounding loop. R_G (t); S3. Calculate the voltage V generated by the mutual inductance and mutual capacitance between the three-phase wire cores A, B, and C and the shielding layer. ABC (t); S4. Calculate the ground wire current attenuation factor α in the absence of faults; S5. Calculate the characteristic components of the grounding wire current in the absence of faults S6. Based on steps S4 and S5, find the current expression of the connecting wire in the case of no fault. S7. Based on the grounding wire current solved in S6, the steady-state grounding wire current expression is obtained by taking the limit.
2. The method for calculating the current of a mining cable grounding wire according to claim 1, characterized in that: The method further includes S8, when a line fault occurs, based on steps S2, S3, S4, S5, S6 and S7, solving the steady-state current expression of the fault line grounding line and the steady-state current expression of the non-fault line grounding line under the fault condition.
3. The method for calculating the current of a mining cable grounding wire according to claim 1, characterized in that: In S2, find the sum of the mutual inductive reactance and mutual capacitive reactance voltage V generated by the power core D and the control core E to the shield layer or the grounding core. R_G (t): Among them, R AM is the mutual inductance resistance, L AM Mutual inductance reactance, l is the cable length, is the voltage of the power core and the control core at the beginning of the line. The current of the power core and the control core at the beginning of the line. is the voltage at the beginning of the grounding core, C AM is the mutual capacitance between the cables.
4. The method for calculating the current of a mining cable grounding wire according to claim 3 is characterized in that: In S3, find the sum of the mutual inductive reactance and mutual capacitive reactance voltage V generated between the three-phase cores A, B, and C and the shielding layer. ABC (t): in, is the voltage at the beginning of each phase core, It is the shielding voltage at the beginning of each phase core.
5. A method for calculating the current of a mining cable grounding wire according to claim 4, characterized in that: In S4, find the ground wire current attenuation factor α in the absence of faults: Among them, Rg is the grounding resistance.
6. A method for calculating the current of a mining cable grounding wire according to claim 5, characterized in that: In S5, find the characteristic component of the grounding wire current in the absence of faults.
7. The method for calculating the current of a mining cable grounding wire according to claim 1, characterized in that: In S6, the ground wire current is calculated based on steps S4 and S5. The expression is as follows: Where C1 is a constant.
8. A method for calculating the current of a mining cable grounding wire according to claim 7, characterized in that: In S7, by taking the limit, the ground wire current after stabilization is calculated. The expression is as follows:
9. A method for calculating the current of a mining cable grounding wire according to claim 8, characterized in that: In S8, the expression of the ground wire current after stabilization is as follows: In the case of a fault, the zero-sequence current of the fault-free line affects V 0sumW (t) is expressed as follows: in, is the sum of the three-phase currents of the fault-free line, is the i-phase current of the fault-free line, i = A, B, C; In the case of a fault, the sum of the currents of the power core and control core of the fault-free line is V DEW (t) is expressed as follows: in, is the power core and control core current of the fault-free line, p = D, E; In the event of a fault, after the current of the fault-free grounding wire stabilizes The expression is as follows: Among them, α is the attenuation factor; In the case of a fault, the zero-sequence current of the fault line affects V 0sumf (t) is expressed as follows: in, is the sum of the three-phase currents of the fault line, is the i-phase current of the fault line, i = A, B, C, x is the fault distance; In the case of a fault, the sum of the currents of the power core and control core of the fault line V DEf (t) is expressed as follows: in, is the power core and control core current of the fault line, p = D, E; In the event of a fault, after the fault grounding current stabilizes The expression is as follows: