Power facility diagnosis method using feeder remote terminal unit

Abstract

The present invention relates to a method for diagnosing the status of a switch using a Feeder Remote Terminal Unit (FRTU). The present invention includes the steps of: calculating a nonlinear coefficient between a load current and a voltage drop based on a load current measured at a switch and a voltage drop of a distribution line; calculating a harmonic distortion rate using a measured voltage measured at the switch; and diagnosing whether deterioration of the switch has occurred based on the nonlinear coefficient and the harmonic distortion rate.

Description

Technology Field

[0001] The present invention relates to a method for diagnosing the status of a switch using a Feeder Remote Terminal Unit (FRTU). Background Technology

[0003] Switches, one of the key facilities in the power distribution system, are installed on high-voltage distribution lines and measure the voltage and current of the lines through Potential Transformers (PTs) and Current Transformers (CTs), serving to supply (close) or cut off (open) power.

[0004] A distribution automation terminal unit (FRTU) is installed in the switchgear control box to convert analog signals measured by the switchgear into digital signals (Analog to Digital Converter, ADC), analyze data such as voltage, current, and frequency, as well as conditions such as overcurrent, fault, and voltage abnormality, and then transmit them to a central control system so that the status of the distribution line can be managed in real time.

[0005] However, in power distribution systems, power equipment such as switches is maintained by dispatching personnel to the site to check their condition or perform preventive inspections.

[0006] In particular, compared to the increasing scale of power facilities, the method of on-site inspection requires a significant amount of time and manpower, leading to increased economic burden and potential issues such as omission of inspection items or uninspected locations.

[0007] In addition, there are inspection items that are difficult to check directly on-site, making it difficult to accurately diagnose the actual state of aging. Prior art literature

[0009] Korean Patent Publication No. 10-2297005 (Registration Date: August 27, 2021) The problem to be solved

[0010] The present invention aims to diagnose the deterioration status of a switchgear using a distribution automation terminal unit (FRTU).

[0011] The objects of the present invention are not limited to those mentioned above, and other unmentioned objects and advantages of the present invention may be understood from the following description and will be more clearly understood by the embodiments of the present invention. Furthermore, it will be readily apparent that the objects and advantages of the present invention can be realized by the means and combinations thereof set forth in the claims. means of solving the problem

[0013] The present invention includes the steps of: calculating a nonlinear coefficient between a load current and a voltage drop based on a load current measured at a switch and a voltage drop of a distribution line; calculating a harmonic distortion rate using a measured voltage measured at the switch; and diagnosing whether deterioration of the switch has occurred based on the nonlinear coefficient and the harmonic distortion rate.

[0014] In one embodiment, the step of calculating the nonlinear coefficient may calculate the nonlinear coefficient through the voltage drop measured according to the average load current over time.

[0015] In one embodiment, the step of calculating the harmonic distortion rate may calculate the harmonic distortion rate based on the analyzed frequency after frequency analysis of the measured voltage.

[0016] In one embodiment, the diagnosing step may include a step of calculating an initial nonlinear coefficient through an initial load current and an initial voltage drop measured at the switch and setting a threshold value, a step of calculating a normal harmonic distortion rate through an initial measured voltage measured at the switch and setting a reference value, and a step of comparing the calculated nonlinear coefficient with the threshold value and comparing the calculated harmonic distortion rate with the reference value.

[0017] In one embodiment, the diagnosing step may diagnose the occurrence of deterioration of the switchgear if the calculated nonlinear coefficient is greater than or equal to the threshold value and the calculated harmonic distortion rate is greater than or equal to the reference value.

[0018] In one embodiment, the diagnosing step may utilize a neural network model that receives the nonlinear coefficient and harmonic distortion rate as input and outputs a binary label corresponding to whether deterioration of the switchgear has occurred.

[0019] In one embodiment, the neural network model can predict the rate of deterioration of the switchgear by analyzing the change patterns of the nonlinear coefficients and harmonic distortion rates. Effects of the invention

[0021] The present invention has the effect of reducing economic burden by diagnosing the deterioration status of switches using a distribution automation terminal unit (FRTU), thereby evaluating the degree of aging of the switches and reducing unnecessary equipment replacement and inspection.

[0022] In addition to the effects described above, the specific effects of the present invention are described together with the specific details for implementing the invention below. Brief explanation of the drawing

[0024] FIG. 1 is a method for diagnosing power facilities using a distribution automation terminal device according to an embodiment of the present invention, FIG. 2 shows a diagnosing step of a power facility diagnosis method using a distribution automation terminal device according to an embodiment of the present invention, FIG. 3 is a neural network model of a power facility diagnosis method using a distribution automation terminal device according to an embodiment of the present invention. Specific details for implementing the invention

[0025] The aforementioned objectives, features, and advantages are described in detail below with reference to the attached drawings, thereby enabling those skilled in the art to easily implement the technical concept of the present invention. In describing the present invention, detailed descriptions of known technologies related to the present invention are omitted if it is determined that such descriptions would unnecessarily obscure the essence of the invention. Hereinafter, preferred embodiments according to the present invention will be described in detail with reference to the attached drawings. In the drawings, the same reference numerals are used to indicate the same or similar components.

[0026] In this specification, terms such as "first," "second," etc. are used to describe various components, but these components are not limited by these terms. These terms are used merely to distinguish one component from another, and unless specifically stated otherwise, the first component may be the second component.

[0027] Additionally, in this specification, the statement that any configuration is disposed on the "upper (or lower)" or "upper (or lower)" of a component may mean not only that any configuration is disposed in contact with the upper (or lower) surface of said component, but also that another configuration may be interposed between said component and any configuration disposed on (or below) said component.

[0028] Furthermore, where it is stated in this specification that one component is "connected," "coupled," or "connected" to another component, it should be understood that while the components may be directly connected or connected to each other, another component may be "interposed" between each component, or each component may be "connected," "coupled," or "connected" through another component.

[0029] Additionally, singular expressions used in this specification include plural expressions unless the context clearly indicates otherwise. In this application, terms such as "composed of" or "comprising" should not be interpreted as necessarily including all of the various components or steps described in the specification, and should be interpreted as meaning that some of the components or steps may not be included, or that additional components or steps may be included.

[0030] Additionally, in this specification, "A and / or B" means A, B, or A and B unless specifically stated otherwise, and "C to D" means C or more and D or less, unless specifically stated otherwise.

[0031] The present invention relates to a method for diagnosing the condition of power equipment, such as a switch, in a power distribution system. Hereinafter, a method for diagnosing power equipment using a power distribution automation terminal device according to some embodiments of the present invention will be described with reference to FIGS. 1 to 3.

[0032] The switchgear is installed on a 22.9kV high-voltage distribution line and can measure the load current and measured voltage of the distribution line through a PT (Potential Transformer) and a CT (Current Transformer).

[0033] In addition, since the load current can vary by time of day and season, the switch can measure and analyze the voltage drop according to changes in the load current. That is, voltage drop is a decrease in potential along the path of the current flowing in the distribution line, and is measured according to each load current in sections where the load current is kept constant, and can be calculated and measured according to [Equation 1] below.

[0034] [Mathematical Formula 1]

[0035]

[0036] Here is a reference voltage measured at the sending side of the distribution line when the distribution system is operating normally, and is the measured voltage actually measured through the switch, and is the voltage drop that occurs through the switch.

[0037] When the switch operates normally, the resistance of the distribution line is constant, so it can maintain a linear relationship with the load current. That is, it can be defined as in [Equation 2].

[0038] [Mathematical Formula 2]

[0039]

[0040] Here is the voltage drop occurring through the switch, and is the internal resistance value of the switch, and is the load current actually measured through the switch.

[0041] At this time This is the section input from the switchgear's Potential Transformer (PT) to the Distribution Automation Terminal Unit (FRTU), and since it is necessary to analyze the switchgear's status in the event of abnormal operation, it can be calculated through the Distribution Automation Terminal Unit (FRTU). Accordingly, It can be calculated using [Equation 2], and can be calculated by substituting the voltage drop and load current values ​​measured through the switch.

[0042] However, accurate To calculate it, the voltage drop and load current measured when the switch is operating normally are required. In other words, accurate voltage drop calculation and To ensure reliability, the initial load current and initial measured voltage measured when the switchgear is first installed must be stored in advance in the distribution automation terminal unit (FRTU).

[0043] The distribution automation terminal unit (FRTU) can be the subject of diagnosis regarding the occurrence of deterioration of the switchgear described below, and to perform the operation described below, it may include at least one physical element among ASICs (application specific integrated circuits), DSPs (digital signal processors), DSPDs (digital signal processing devices), PLDs (programmable logic devices), FPGAs (field programmable gate arrays), controllers, processors, microprocessors, and microcontrollers.

[0044] The Distribution Automation Terminal Unit (FRTU) can collect and store load current, measured voltage, and voltage drop from switches in real time, and by storing the switch's installation date, operating period, operation history, and fault history, it can not only manage the status and operation records of the distribution line but also efficiently track the operating status and lifespan of the switch.

[0045] Referring to FIG. 1, the distribution automation terminal unit (FRTU) can calculate a non-linear coefficient between the load current and the voltage drop based on the load current measured at the switch and the voltage drop of the distribution line (S100).

[0046] The reason for calculating these nonlinear coefficients is that as the switchgear deteriorates, the voltage drop, which maintains a linear relationship with the load current, deviates from linear characteristics and changes nonlinearly.

[0047] When the deterioration of the switchgear progresses, the voltage drop that changes non-linearly can be defined as shown in [Equation 3] below.

[0048] [Mathematical Formula 3]

[0049]

[0050] Here is the voltage drop occurring through the switch, and is the resistance value of the distribution line, and is the load current actually measured through the switch, and class is a nonlinear coefficient.

[0051] nonlinear coefficient class It can be calculated using [Equation 3], and while it has a value close to 0 when the switch is normal, as deterioration progresses, the value increases and exhibits non-linearity of voltage drop.

[0052] In addition, the nonlinear coefficient can be calculated based on the time-series average load current measured at the switchgear and the voltage drop measured during that time period; by being calculated through the relationship between the time-series average load current and the voltage drop, it can help diagnose the degree of deterioration of the switchgear.

[0053] The distribution automation terminal unit (FRTU) can calculate the harmonic distortion rate using the measured voltage from the switchgear (S200).

[0054] Total Harmonic Distortion (THD) represents the ratio of harmonic components contained in the fundamental frequency component and is an indicator that quantitatively evaluates harmonic distortion caused by harmonics that are multiples of the fundamental frequency component. If a switch operates abnormally due to external factors or internal degradation, the harmonic components included in the voltage or current signals increase, making it more likely that distortion will intensify and consequently causing the THD value to rise.

[0055] The total harmonic distortion (THD) can be calculated based on the analyzed frequency after frequency analysis of the measured voltage at the switchgear.

[0056] First, since the measured voltage can include harmonic components as well as the fundamental frequency, the frequency components can be analyzed through methods such as the Fourier Transform.

[0057] The reason for frequency analysis of the measured voltage is that it is difficult to separate harmonic components using only the voltage measured over time; therefore, converting it to the frequency domain allows for the accurate determination of the magnitude of each harmonic component.

[0058] Based on the analyzed frequency, the total harmonic distortion (THD) can be calculated using [Equation 4] below.

[0059] [Mathematical Formula 4]

[0060]

[0061] Here is the voltage of the fundamental frequency component, and is the voltage of the nth harmonic component (e.g., is the second harmonic (120Hz), is the third harmonic (180Hz).

[0062] The total harmonic distortion (THD) can be accumulated and stored in the distribution automation terminal unit (FRTU) from the beginning, which can help analyze whether harmonic generation or change is caused by external factors of the switchgear or by the deterioration of the switchgear itself.

[0063] The nonlinear coefficients calculated as above ( class Based on ) and the total harmonic distortion (THD), it is possible to diagnose whether the switch has deteriorated (S300).

[0064] Referring to FIG. 2, for this purpose, a standard for diagnosing the deterioration of a switch can be established using the load current and measured voltage measured in the initial state after the switch is first installed. Specifically, an initial nonlinear coefficient is calculated using the initial load current and initial voltage drop measured at the switch to set a threshold value (S310), and a normal harmonic distortion rate is calculated using the initial measured voltage measured at the switch to set a reference value (S320).

[0065] The reason for calculating the initial nonlinear coefficient is that it is calculated using the initial load current and initial voltage drop measured in the initial state where the switch is installed; therefore, it represents a value that minimizes nonlinear characteristics in an environment where the switch operates normally.

[0066] Accordingly, by calculating an initial nonlinear coefficient and setting it as a threshold, it can serve as a criterion for determining abnormal operating conditions, such as deterioration, based on the normal operating state of the switchgear; subsequently, it becomes possible to determine whether deterioration of the switchgear has occurred by comparing it with the nonlinear coefficient calculated based on the load current and voltage drop measured in real time.

[0067] The reason for calculating the normal harmonic distortion is that it is calculated using the initial measured voltage obtained from the initial state where the switch is installed, allowing the harmonic characteristics under normal operating conditions to be set as a reference value.

[0068] In other words, by calculating the normal harmonic distortion rate and setting it as a reference value, it is possible to determine whether changes in harmonic components are within the normal range by comparing them with subsequently calculated harmonic distortion rates, and in particular, it becomes possible to analyze whether the generation of harmonics is caused by external factors or internal degradation.

[0069] After the threshold and reference values ​​are set as above, the calculated nonlinear coefficient and harmonic distortion rate are compared (S330).

[0070] Specifically, the nonlinear coefficient calculated based on the load current and voltage drop measured from the switch after the threshold is set is compared with the threshold, and the harmonic distortion rate calculated based on the measured voltage from the switch after the reference value is set is compared with the reference value. In this case, if the calculated nonlinear coefficient is greater than or equal to the threshold and the calculated harmonic distortion rate is greater than or equal to the reference value, it can be diagnosed as deterioration of the switch.

[0071] The reason for simultaneously comparing nonlinear coefficients and harmonic distortion is that they directly reflect the condition and performance degradation of the switchgear, thereby improving diagnostic accuracy. In other words, since nonlinear coefficients can assess switchgear deterioration and harmonic distortion can determine whether the deterioration is due to external or internal factors, if both the nonlinear coefficient and the harmonic distortion exceed a reference value, it serves as clear evidence that the switchgear is operating abnormally due to deterioration; however, if only one of these values ​​exceeds the threshold or reference value, it suggests the possibility that the phenomenon is temporary and caused by external factors.

[0072] Meanwhile, a neural network model may also be used to diagnose whether deterioration has occurred in the switchgear.

[0073] The Distribution Automation Terminal Unit (FRTU) identifies whether deterioration of the switchgear has occurred by inputting nonlinear coefficients and harmonic distortion rates into a neural network model, and if deterioration of the switchgear is identified, it can predict the rate of deterioration progression of the switchgear by analyzing the change patterns of the nonlinear coefficients and harmonic distortion rates input into the neural network model.

[0074] The neural network model can receive nonlinear coefficients and harmonic distortion as input and perform supervised learning in advance. Specifically, the neural network model can acquire learning nonlinear coefficients and learning harmonic distortion calculated using load current, voltage drop, and measured voltage continuously collected from the switchgear according to the aforementioned method, and can perform supervised learning to determine whether degradation of the switchgear has occurred using the learning nonlinear coefficients and learning harmonic distortion.

[0075] Referring to Fig. 3, the neural network model sets nonlinear coefficients for learning and harmonic distortion rates for learning as input data, and sets a binary label corresponding to whether deterioration of the switchgear has occurred. In this case, the binary label can be supervised learning by setting Class 1 when deterioration of the switchgear occurs and Class 0 when normal as output data of the neural network model.

[0076] In addition, if the neural network model identifies the occurrence of switchgear degradation, it is possible to predict how quickly the degradation is progressing based on the accumulated data.

[0077] At this time, the reliability of the result determining whether deterioration has occurred in the switch can be improved by adding the switch's temperature and humidity values, installation date and operating period, operation history, and failure history as input data to the neural network model.

[0078] The Distribution Automation Terminal Unit (FRTU) can notify the operator terminal of the switch's deterioration status after diagnosing whether deterioration has occurred in the switch as described above. For example, if deterioration is diagnosed, it can notify as a caution or danger, and if deterioration is diagnosed as not occurring, it can notify as normal.

[0079] Specifically, if deterioration of the switch is diagnosed, a warning or danger alert may be issued depending on whether the deterioration is caused by external factors or is internal, or based on the rate of deterioration progression. Additionally, by transmitting the switch's installation date, operating period, operation history, and failure history to the operator's terminal, it can assist the operator in making a comprehensive assessment of the switch's aging and abnormal conditions.

[0080] As described above, by diagnosing whether deterioration has occurred in the switchgear, it is possible to detect the occurrence of deterioration early based on the change pattern over time. In particular, since the deterioration is determined by detecting non-linear changes that increase as the switchgear deteriorates, rather than simply detecting changes in voltage drop, the reliability of the diagnostic results can be improved, and it is also effective in predicting the degree of aging and abnormal conditions of the switchgear in advance.

[0081] In addition, it enables operators to efficiently manage the status of switches and perform immediate maintenance, thereby maximizing the stability and economic efficiency of the power system.

[0082] In addition, the present invention can be used to diagnose whether deterioration has occurred in power equipment such as transformers and circuit breakers, as well as switchgear.

[0083] Although the present invention has been described above with reference to the illustrated drawings, the present invention is not limited by the embodiments and drawings disclosed in this specification, and it is obvious that various modifications can be made by a person skilled in the art within the scope of the technical concept of the present invention. Furthermore, even if the effects of the configuration of the present invention were not explicitly described while explaining the embodiments of the present invention above, it is natural to acknowledge that the effects predictable by said configuration should also be recognized.

Claims

Claim 1 A method for diagnosing power equipment, comprising: a step of calculating a nonlinear coefficient between a load current and a voltage drop based on a load current measured at a switch and a voltage drop of a distribution line; a step of calculating a harmonic distortion rate using a measured voltage measured at the switch; and a step of diagnosing whether deterioration of the switch has occurred based on the nonlinear coefficient and the harmonic distortion rate. Claim 2 A power equipment diagnostic method according to claim 1, wherein the step of calculating the nonlinear coefficient is to calculate the nonlinear coefficient through a voltage drop measured according to the average load current over time. Claim 3 A power equipment diagnostic method according to claim 1, wherein the step of calculating the harmonic distortion rate comprises calculating the harmonic distortion rate based on the analyzed frequency after frequency analysis of the measured voltage. Claim 4 A method for diagnosing power equipment according to claim 1, wherein the diagnosing step comprises: a step of setting a threshold value by calculating an initial nonlinear coefficient through an initial load current and an initial voltage drop measured at the switch; a step of setting a reference value by calculating a normal harmonic distortion rate through an initial measured voltage measured at the switch; and a step of comparing the calculated nonlinear coefficient with the threshold value and comparing the calculated harmonic distortion rate with the reference value. Claim 5 A method for diagnosing power equipment according to claim 4, wherein the diagnosing step diagnoses the occurrence of deterioration of the switchgear if the calculated nonlinear coefficient is greater than or equal to the threshold value and the calculated harmonic distortion rate is greater than or equal to the reference value. Claim 6 A method for diagnosing power equipment according to claim 1, wherein the diagnosing step utilizes a neural network model that receives the nonlinear coefficient and harmonic distortion rate as input and outputs a binary label corresponding to whether deterioration of the switchgear has occurred. Claim 7 A power equipment diagnostic method according to claim 6, wherein the neural network model predicts the rate of deterioration of a switchgear by analyzing the change pattern of the nonlinear coefficient and harmonic distortion rate.

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