A non-intrusive online monitoring method for mechanical defects of combined electrical isolation switches

Abstract

The present invention belongs to the technical field of power grid equipment monitoring, and specifically relates to a non-invasive online monitoring method for mechanical defects of a combination electrical disconnector; the method comprises: installing a motor power acquisition device inside the combination electrical disconnector mechanism box to obtain a real-time motor power curve during the opening and closing process of the combination electrical disconnector; obtaining key parameters of the motor of the combination electrical disconnector; simplifying the structure diagram according to the motor power transmission model to obtain the transfer function of the motor power during the opening and closing process, and performing an inverse Laplace transform to obtain a time domain analytical model of the motor power; calculating the time interval nodes for determining mechanical defects of the combination electrical disconnector according to the time domain analytical model to determine whether there is a defect in the combination electrical disconnector. The present invention can accurately determine whether there is a mechanical defect in the combination electrical disconnector, thereby increasing the reliability of the equipment and avoiding the serious consequences caused by inadequate opening and closing, thereby ensuring the safe operation of the power grid.

Description

Technical Field

[0001] The present invention belongs to the technical field of power grid equipment monitoring, and in particular relates to a non-invasive online monitoring method for mechanical defects of a combined electrical appliance isolating switch. Background Art

[0002] A gas-insulated metal-enclosed switchgear (GIS) is a high-voltage electrical device that connects individual components such as circuit breakers, disconnectors, grounding / fast-grounding switches, current transformers, voltage transformers, lightning arresters, and busbars. These components are enclosed in a metal enclosure and, together with the outgoing line bushings, cables, and control cabinets, are filled with SF6 gas at a certain pressure as an arc-extinguishing and insulating medium. Also known as a high-voltage combination electrical device (hereinafter referred to as a combination electrical device), combination electrical devices have been widely used in power systems due to their advantages such as small footprint, reduced space consumption, high operational reliability, and minimal maintenance. They are the core primary equipment in substations.

[0003] Combination electrical equipment, filled with SF6 gas, has a dense and complex internal structure, making maintenance difficult, technically demanding, and resulting in widespread power outages and long maintenance cycles. The resulting grid risks from internal failures are extremely severe. Analysis of several combination electrical disconnector failures within the system revealed that most were due to mechanical defects that could not be detected by conventional testing methods in their early stages. Mechanical defects are particularly difficult to detect. Therefore, effective and reliable testing and diagnosis are crucial to promptly detect and eliminate opening and closing defects in combination electrical disconnectors, thereby preventing more serious equipment and grid accidents. This has become an urgent need to improve the reliability of combination electrical equipment. Summary of the Invention

[0004] The purpose of the present invention is to overcome the shortcomings of the existing technology and provide a non-invasive online monitoring method for mechanical defects of combination electrical isolating switches, so as to realize online monitoring of the actual operating status of the combination electrical isolating switches in operation, make timely warnings of mechanical defects and normal position status, and improve the operating reliability and safety of combination electrical equipment.

[0005] The object of the present invention is achieved as follows: a non-intrusive online monitoring method for mechanical defects of a combination electrical isolation switch comprises the following steps:

[0006] Step 1: Install a motor power acquisition device inside the combination electrical isolation switch mechanism box, measure the motor power in real time through the Internet of Things device, and obtain the real-time motor power curve P during the opening and closing process of the combination electrical appliance. S (t);

[0007] Step 2: Obtain the mechanical gain coefficient K of the motor of the combination electrical isolation switch according to the given parameters of the combination electrical isolation switch manufacturer. q, damping coefficient ξ, motor inertia H, adjustment coefficient R, time constant T1 and resistance work P e ;

[0008] Step 3: Simplify the structure diagram according to the motor power transmission model to obtain the transfer function of the motor power during the opening and closing process. After obtaining the transfer function, transform it into the time domain to obtain a time domain analytical model;

[0009] Step 4: Calculate the time interval nodes for determining mechanical defects of the combination electrical isolating switch based on the time domain analytical model, and use the normal judgment criteria to determine whether there is a defect in the combination electrical isolating switch by judging the motor power.

[0010] Furthermore, the parameters given by the manufacturer of the combination electrical isolating switch in step 2 are obtained from the manufacturer's drawings based on the operating requirements of the power system.

[0011] Furthermore, step 3 includes performing an inverse Laplace transform on the obtained motor power transfer function, thereby obtaining a time domain analytical model of the motor power during the opening and closing process; wherein the mechanical gain coefficient K of the motor of the combination electrical disconnector is q Calculated by formula (1),

[0012]

[0013] Among them, S q is the transmission power of each mechanical part, S re For total power consumption, both are measured in a laboratory environment and are provided by the manufacturer;

[0014] By simplifying the structure diagram of the motor power transmission model, the frequency domain expression of the motor power is obtained as shown in formula (2):

[0015]

[0016] Among them, P S is the motor power, R is the adjustment coefficient, K q is the motor mechanical gain coefficient, D is the mechanical damping, its value is generally 1, P e is the resistance work, ω n is the natural angular frequency, ξ is the damping coefficient of the motor;

[0017] Natural angular frequency ω n , the damping coefficient ξ of the motor is calculated as shown in equations (3)-(4).

[0018]

[0019] Converting Equation (2) to the time domain, we can obtain the time domain analytical model of the motor power of the combined electrical disconnector in the opening and closing process as shown in Equation (5).

[0020]

[0021] Among them, ω r 、 A is an intermediate calculation variable, and its expression is shown in formulas (6)-(8).

[0022]

[0023] Furthermore, in step 4, the mechanical defect determination time interval node t of the combined electrical isolation switch is z By taking the derivative of formula (5) with respect to time, we can get formula (9):

[0024]

[0025] Normal criterion parameter P for the first interval of mechanical defect of combined electrical disconnector Smin Calculated by formula (10),

[0026]

[0027] In the first range of motor power, the following conditions must be met: the actual measured motor power P S (t)≥P Smin ;

[0028] Normal judgment parameter P of the second interval of mechanical defect of combined electrical disconnector Sw Calculated by formula (11),

[0029]

[0030] The second range of motor power must meet the following requirements: the actual measured motor power is 0.8P Sw ≤P S (t)≤1.2P Sw .

[0031] Beneficial effects of the present invention: A non-invasive online monitoring method for mechanical defects of a combination electrical isolating switch of the present invention is achieved by: installing a motor power acquisition device inside the combination electrical isolating switch mechanism box to obtain a real-time motor power curve during the opening and closing process of the combination electrical isolating switch; obtaining key parameters of the motor of the combination electrical isolating switch according to the given parameters of the combination electrical isolating switch manufacturer; simplifying the structural diagram according to the motor power transmission model to obtain the transfer function of the motor power during the opening and closing process, and performing an inverse Laplace transform to obtain a time domain analytical model of the motor power; calculating the time interval nodes for determining the mechanical defects of the combination electrical isolating switch according to the time domain analytical model, and using normal judgment criteria to determine the motor power to determine whether there is a defect in the combination electrical isolating switch; being able to monitor online whether the opening and closing of the combination electrical isolating switch is in place based on the known key parameters of the motor of the combination electrical isolating switch and the measured motor power during the opening and closing process, accurately determining whether there is a mechanical defect in the combination electrical isolating switch, thereby increasing the reliability of the equipment and avoiding the serious consequences caused by inadequate opening and closing, thereby ensuring the safe operation of the power grid. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0033] Figure 1 It is the actual power curve of the normal opening and closing of the motor of the combination electrical disconnector.

[0034] Figure 2 It is the actual power curve of abnormal opening and closing of the motor of the combination electrical disconnector. DETAILED DESCRIPTION

[0035] The present invention will be further described below with reference to the accompanying drawings.

[0036] It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention.

[0037] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. All other embodiments obtained by ordinary technicians in this field based on the embodiments of the present invention without making any creative efforts shall fall within the scope of protection of the present invention.

[0038] A non-intrusive online monitoring method for mechanical defects of a combination electrical appliance isolating switch of the present invention comprises the following steps:

[0039] Step 1: Install a motor power acquisition device inside the combination electrical isolation switch mechanism box, measure the motor power in real time through the Internet of Things device, and obtain the real-time motor power curve P during the opening and closing process of the combination electrical appliance. S (t), go to step 2 after completion.

[0040] Step 2: Obtain the mechanical gain coefficient K of the motor of the combination electrical isolation switch according to the given parameters of the combination electrical isolation switch manufacturer. q , damping coefficient ξ, motor inertia H, adjustment coefficient R, time constant T1 and resistance work P e The parameters given by the manufacturer of the combination electrical isolating switch in step 2 are obtained from the manufacturer's drawings based on the operating requirements of the power system.

[0041] Step 3: Simplify the structure diagram according to the motor power transmission model to obtain the transfer function of the motor power during the opening and closing process. After obtaining the transfer function, transform it into the time domain to obtain a time domain analytical model;

[0042] Furthermore, step 3 includes performing an inverse Laplace transform on the obtained motor power transfer function, thereby obtaining a time domain analytical model of the motor power during the opening and closing process; wherein the mechanical gain coefficient K of the motor of the combination electrical disconnector is q Calculated by formula (1),

[0043]

[0044] Among them, S q is the transmission power of each mechanical part, S re For total power consumption, both are measured in a laboratory environment and are provided by the manufacturer;

[0045] The damping coefficient ξ, motor inertia H, adjustment coefficient R, time constant T1, and resistance work P of the combined electrical disconnector motor e They are also provided by the equipment when it leaves the factory. The structure diagram is simplified through the motor power transmission model to obtain the frequency domain expression of the motor power as shown in formula (2).

[0046]

[0047] Among them, P S is the motor power, R is the adjustment coefficient, K q is the motor mechanical gain coefficient, D is the mechanical damping, its value is generally 1, P e is the resistance work, ω n is the natural angular frequency, ξ is the damping coefficient of the motor;

[0048] Natural angular frequency ω n , the damping coefficient ξ of the motor is calculated as shown in equations (3)-(4).

[0049]

[0050] Converting Equation (2) to the time domain, we can obtain the time domain analytical model of the motor power of the combined electrical disconnector in the opening and closing process as shown in Equation (5).

[0051]

[0052] Among them, ω r 、 A is an intermediate calculation variable, and its expression is shown in formulas (6)-(8).

[0053]

[0054]

[0055] Step 4: Calculate the time interval nodes for determining mechanical defects of the combination electrical isolating switch based on the time domain analytical model, and use the normal judgment criteria to determine whether there is a defect in the combination electrical isolating switch by judging the motor power.

[0056] Furthermore, in step 4, the mechanical defect determination time interval node t of the combined electrical isolation switch is z By taking the derivative of formula (5) with respect to time, we can get formula (9):

[0057]

[0058] Normal criterion parameter P for the first interval of mechanical defect of combined electrical disconnector Smin Calculated by formula (10),

[0059]

[0060] In the first range of motor power, the following conditions must be met: the actual measured motor power P S (t)≥P Smin ;

[0061] Normal judgment parameter P of the second interval of mechanical defect of combined electrical disconnector Sw Calculated by formula (11),

[0062]

[0063] The second range of motor power must meet the following requirements: the actual measured motor power is 0.8P Sw ≤P S (t)≤1.2PSw .

[0064] The method of the present invention is further illustrated below using a combination electrical disconnector motor in an experimental environment. The key parameters of the motor are as follows:

[0065]

[0066] The experimental design is divided into two parts. The first is that the power of the motor of the combination electrical disconnector under normal conditions meets the normal criterion. The actual power curve of the normal opening and closing of the motor of the combination electrical disconnector is as follows: Figure 1 As shown, the motor parameters are substituted into formula (10) to obtain P Smin 357.64W, 0.9P Smin The actual power curve in the first period is above 330W, which meets the requirements. Substituting the motor parameters into formula (11) yields P Sw 549.16W, 0.8P Sw The set value is 439.32W, 1.2P Sw The set value is 658.99W, and the actual power curve in the second time period is within [439.32, 658.99] to meet the requirements.

[0067] Secondly, the power of the motor of the combination electrical disconnector under abnormal conditions does not meet the normal judgment criteria. The actual power curve of the abnormal opening and closing of the motor of the combination electrical disconnector is as follows: Figure 2 As shown, the actual power curve meets the requirements above 330W in the first time period. However, the actual power curve exceeds the range of [439.32, 658.99] in the second time period due to the mechanical defect of the connecting rod falling off. Therefore, it can be judged that there is a mechanical defect.

[0068] After comparison, it was found that the method of the present invention can accurately identify the defect of the combined electrical appliance disconnector not being opened or closed properly.

[0069] In summary, the present invention provides a non-invasive online monitoring method for mechanical defects of a combination electrical isolating switch, which comprises the following steps: installing a motor power acquisition device inside a combination electrical isolating switch mechanism box to obtain a real-time motor power curve during the opening and closing process of the combination electrical isolating switch; obtaining key parameters of the combination electrical isolating switch motor based on parameters given by the combination electrical isolating switch manufacturer; simplifying the structure diagram based on a motor power transmission model to obtain a transfer function of the motor power during the opening and closing process, and performing an inverse Laplace transform to obtain a time domain analytical model of the motor power; calculating a time interval node for determining mechanical defects of the combination electrical isolating switch based on the time domain analytical model, and using a normal judgment criterion to determine whether the motor power is defective in the combination electrical isolating switch; based on the known key parameters of the combination electrical isolating switch motor, online monitoring can be performed to determine whether the opening and closing of the combination electrical isolating switch is in place based on the measured motor power during the opening and closing process, and accurately determining whether the combination electrical isolating switch has mechanical defects, thereby increasing equipment reliability and avoiding serious consequences caused by inadequate opening and closing, thereby ensuring the safe operation of the power grid.

[0070] Throughout this specification, references to terms such as "one embodiment," "example," or "specific example" indicate that the specific features, structures, materials, or characteristics described in conjunction with that embodiment or example are included in at least one embodiment or example of the present invention. In this specification, schematic representations of these terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in any one or more embodiments or examples.

[0071] The basic principles, main features, and advantages of the present invention are shown and described above. Those skilled in the art should understand that the present invention is not limited to the above embodiments. The above embodiments and descriptions are merely illustrative of the principles of the present invention. Various changes and modifications may be made to the present invention without departing from the spirit and scope of the present invention, and such changes and modifications fall within the scope of the invention as claimed.

Claims

1. A non-intrusive online monitoring method for mechanical defects of a combination electrical isolation switch, characterized in that: The following steps are involved: Step 1: Install a motor power acquisition device inside the combination electrical isolation switch mechanism box, measure the motor power in real time through the Internet of Things device, and obtain the real-time motor power curve P during the opening and closing process of the combination electrical appliance. S (t); Step 2: Obtain the mechanical gain coefficient K of the motor of the combination electrical isolation switch according to the given parameters of the combination electrical isolation switch manufacturer. q , damping coefficient ξ, motor inertia H, adjustment coefficient R, time constant T1 and resistance work P e ; Step 3: Simplify the structure diagram according to the motor power transmission model to obtain the transfer function of the motor power during the opening and closing process. After obtaining the transfer function, transform it into the time domain to obtain a time domain analytical model; Step 4: Calculate the time interval nodes for determining mechanical defects of the combination electrical disconnector according to the time domain analytical model, and use the normal judgment criteria to determine whether the motor power is defective or not. The step 3 includes performing an inverse Laplace transform on the obtained motor power transfer function, thereby obtaining a time domain analytical model of the motor power during the opening and closing process; wherein the mechanical gain coefficient K of the motor of the combination electrical disconnector is q Calculated by formula (1), Among them, S q is the transmission power of each mechanical part, S re is the total power consumed; By simplifying the structure diagram of the motor power transmission model, the frequency domain expression of the motor power is obtained as shown in formula (2): Among them, P S is the motor power, R is the adjustment coefficient, K q is the motor mechanical gain coefficient, D is the mechanical damping, P e is the resistance work, ω n is the natural angular frequency, ξ is the damping coefficient of the motor; Natural angular frequency ω n , the damping coefficient ξ of the motor is calculated as shown in equations (3)-(4). Converting Equation (2) to the time domain, we can obtain the time domain analytical model of the motor power of the combined electrical disconnector in the opening and closing process as shown in Equation (5). Among them, ω r 、 A is an intermediate calculation variable, and its expression is shown in formulas (6)-(8). In step 4, the mechanical defect determination time interval node t of the combined electrical isolation switch is z By taking the derivative of formula (5) with respect to time, we can get formula (9): Normal criterion parameter P for the first interval of mechanical defect of combined electrical disconnector Smin Calculated by formula (10), In the first range of motor power, the following conditions must be met: the actual measured motor power P S (t)≥P Smin ; Normal judgment parameter P of the second interval of mechanical defect of combined electrical disconnector Sw Calculated by formula (11), The second range of motor power must meet the following requirements: the actual measured motor power is 0.8P Sw ≤P S (t)≤1.2P Sw .

2. A non-intrusive online monitoring method for mechanical defects of a combination electrical isolation switch according to claim 1, characterized in that: The parameters given by the manufacturer of the combination electrical disconnect switch in step 2 are obtained from the manufacturer's drawings based on the operating requirements of the power system.

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