Electric disaster pre-detecting and preventing system using internet of things technology

Abstract

The present invention relates to a technology for preventing electrical disasters by detecting abnormal signs of a power grid in advance by measuring characteristics of a line such as electric power loss and line resistance of the line. The present invention detects abnormal signs of a fire that can occur in a distribution power network by using a communication technology such as Internet of Things (IoT) technology to measure physical quantities of a line at all times in a live state at a power supply end and a load end, thereby indirectly measuring electric power loss on the line and line resistance that is a cause thereof, detecting defects of the line, and thereby detecting a fire sign.

Description

TECHNICAL FIELD

[0001] The present invention relates to a technology for preventing an electrical disaster by detecting abnormal signs of an electric power network in advance by measuring and analyzing characteristics of a line such as electric power loss and line resistance of the line. An electrical circuit breaker cuts off supply of electric power to a load if the current exceeds a threshold value set in advance. Although an electrical fire can occur below the safety limit value of the electrical circuit breaker, the prior art has no solution to this.

[0002] The present invention, in order to detect a fire occurrence abnormal sign that can occur in a power distribution network, uses a communication technology such as Internet of Things (IoT) technology to measure physical quantities of a line under a live state at all times at a power supply end and a load end, and indirectly measures electric power loss on the line and line resistance that is a cause thereof, thereby detecting a defect of the line, and further detecting a fire sign. BACKGROUND

[0003] In the existing fire detection technology, a method of monitoring a physical signal that occurs when most fires occur or cutting off a circuit when an allowable current is exceeded is generally used, but it is impossible to prevent a fire that occurs within an allowable tripping current of an overcurrent circuit breaker due to deterioration of a transmission path. The existing current cutoff technology is difficult to detect a fire factor caused by electric power loss of a line. The existing overcurrent circuit breaker is insufficient in countermeasures against ignition caused by heating on a line or sparks such as contact insecurity, electric arc, etc. within a cutoff set current. SUMMARY

[0004] TECHNICAL PROBLEM

[0005] It is very important to detect a defect of an electric power network that supplies electric power, and it affects safety management and preventive maintenance / repair. In particular, it is very important to detect a defect before a disaster occurs. After electrical utilization, many studies have been made to date in order to early detect a defect of an electric power system.

[0006] However, although most electric power systems have a safety device such as an overcurrent circuit breaker, there are still inappropriate supply of electric power to a load of an electric power device and a defect of a line, which can be a serious danger factor. The existing safety device has a region where it cannot be detected even if a dangerous situation occurs. The existing electrical safety technology has a defect in supply of electric power due to abnormality of a line or a circuit breaker connection portion as a unit of supply of electric power, chemical deformation, and line deterioration such as half-circuit, but there is insufficient consideration for this. That is, regardless of the size of a load and the condition of a line, the same existing safety device is relied on.

[0007] The existing overload / leakage cut-off technology can detect overload, short circuit and leakage, thus the accident prevention countermeasures (function) for overload and leakage, which are the main causes of electrical disasters, are solved to some extent, but it cannot detect arc / spark and the like caused by poor contact of lines or switches and the like within the rated electric power.

[0008] The main technology related to safety at present can only detect defects after the electrical defects in the power grid or power system cause the device to malfunction or affect. The existing overcurrent circuit breaker technology still has an area where accidents caused by defects of transmission lines cannot be detected.

[0009] The threshold of the existing protection technology for electrical safety is set by multiplying the maximum value of the available current capacity of the load by a margin. It is a one-line protection mechanism in the case of using one line in a power system with multiple loads. That is, since the protection threshold is determined by the sum of the current capacity of the loads connected to the line, in the case of using a device with heavy load capacity and a load with light load capacity mixed, since the tripping condition is set to be suitable for heavy loads, the light load (short circuit within the rated value of the protector) is relatively deviated from the protection range. The protection mechanism does not work properly according to the allowable capacity of the load or line, but is uniformly applied, so there is a non-detection area of the protection function.

[0010] Also, the existing safety cut-off technology cannot distinguish between hard short circuit and normal load, so the safety technology for detecting hard short circuit or electric shock is insufficient, and thus there is a field where the fire or electric shock danger that exists at present is not detected.

[0011] The existing circuit breaker confirms whether the passing current does not exceed a pre-set level. The arc fault circuit interrupter (AFCI) checks the passing current in order to find the current change indicating Arc defects. This method is a method of confirming whether the current exceeds a pre-set level.

[0012] "Parasitic" resistance is generated due to poor connection, poor contact and aging / deterioration of the line. If a certain condition (R Para ≥V S / I Trip η, η1sec period maintained trip (trip) rate), the parasitic resistance acts as a current limiter, hindering the protection operation when the current of the circuit with defects exceeds the pre-set trip level range of the fuse or circuit breaker used in the circuit. When the total parasitic resistance reaches (R Para =V S / I TripWhen the conditions such as η, η: the trip ratio maintained during 1 sec) are satisfied, a short circuit is very dangerous. At this time, the worst case (P Loss = V S · I Trip · η) is generated.

[0013] Referring to Figure 5

[0014] Technical Solution

[0015] An electrical accident is usually caused by a poor connection, a short circuit, a hard short circuit, connection / disconnection of a load, a short-term line disconnection, or other electrical defects. Therefore, detection of the electrical defects is very important, and if the electrical defects are found before or at the early stage of the accident, damage can be minimized. The present application can estimate the amount of heat generated on a line by actually measuring the electric power consumed on the line receiving the electric power or the line resistance.

[0016] To solve this problem, the technical idea of the present application is to implement an electrical disaster prevention system that (previously) detects / monitors abnormal signs of an accident by collecting data of a power grid having a mesh circuit network form using a (live) measurement technique and an Internet of Things technique (in real time) and finding energy loss due to defects of the power grid by an extended analysis of Kirchhoff's current and voltage laws, (previously) implements a verification / detection mechanism capable of maintaining the integrity of the power grid or operating the power system only within a safe range, and thus fundamentally prevents an electrical disaster.

[0017] In the present application, causes of electrical disasters are roughly classified into two electrical defects as follows. Electrical defects such as leakage, poor / damaged insulation, insulation breakdown (moisture / dust), grounding / mixing, short circuit, tracking, overload / overcurrent, etc. are collectively referred to as parallel defects (Parallel Fault), and electrical defects such as conductor breakage (half-disconnection), connection defects (poor connection), poor contact, crimp damage, etc. are collectively referred to as serial defects (Serial Fault).

[0018] In the present application, most of the electrical defects can be detected in advance by a live detection technique, and thus electric power consumed by all abnormal loads can be detected in real time.

[0019] ​The present invention is a method for automatically taking appropriate measures by always monitoring electrical defects of a power grid, and can detect abnormal signs before chronic static defects / progressive defects develop into an accident, thereby enabling prediction of an accident, and can prevent the disaster in advance if measures are taken. Also, at an early stage, arbitrary / sudden accidents such as a hard short circuit of a live charging circuit (short circuit below the tripping current, electric shock) that the existing protector (circuit breaker, etc.) fails to detect can be detected, and thus, by cutting off the supply of electric power to the power grid, effective measures to prevent the progress of the accident are taken.

[0020] The present invention is a method for detecting abnormal signs by measuring basic electrical characteristics such as voltage, current, etc. of the power supply end and the load end in the live state of the circuit network to measure line resistance, connection parasitic resistance, line loss electric power, leakage current, maximum allowable current of the line, overload, arc phenomenon manifestation, current instability, etc., and analyzing and tracking changes in real time.

[0021] 1. Disaster abnormal sign detection

[0022] The abnormal sign detection technology of the electrical disaster according to the present invention always measures basic physical quantities such as line voltage and current of the power supply end and the load end in the live state, and converts line resistance and line loss electric power in real time, and estimates heat that can be generated on the line, thereby notifying the administrator or eliminating the cause before a major problem occurs, and preventing the actual accident from occurring.

[0023] Also, the actual allowable current due to the decrease in the allowable current caused by the deformation of the line due to the deterioration of the line can be recalculated in a realistic manner. If statistical analysis is performed thereon, the progress of the deterioration of the line can be sensed, and thus, maintenance information such as replacement of the aged line is provided. Although the physical quantities of the remotely distributed network physically separated from the power supply end and the load end can be measured using various communication technologies, if the wireless IoT technology is used, the measurement of the physical quantities can be easily achieved.

[0024] 2. Line defect detection

[0025] The power grid that supplies electric power can have various electrical defects due to various reasons. That is, various forms such as electrical contact, carbonization of the connection portion, incomplete connection, loose connection state, contact resistance, poor contact, connection defect, insulation breakdown, inappropriate setting, damage, half broken wire, physical aging / deformation, and chemical corrosion, etc. can be presented, but in the present invention, the electrical component related to heat generation based on the deterioration phenomenon is expressed as a parasitic resistance 4.

[0026] Figure 2is a basic circuit in which a power source, a transmission path, and a load are connected in series. The cause of a line electrical fire is deterioration of the line and overcurrent. The main cause of a fire occurring in the line can be found in an electrical characteristic change such as an increase in a parasitic resistance (R Para , R FS ) caused by the deterioration of the line. If current flows, an increase in the line resistance generates electrical power loss, which is directly converted into Joule heat, and if it exceeds a predetermined value, it becomes a condition for ignition, and thus, it is necessary to minimize it or to detect in advance whether such a phenomenon exists.

[0027] Since the resistance component in the parasitic element becomes Joule heat if current flows, a line defect caused by an increase in the resistance component is detected. The line deterioration resistance is concentrated in a specific position in a physical sense, and thus, it is more dangerous than a dispersed resistance of a line having the same distributed integer form.

[0028] Electrical energy loss caused by the parasitic resistance of the line is manifested as an increase in dissipated electrical power between both ends of the line or an increase in voltage drop, and a decrease in insulation strength develops into a leakage or a short circuit. Generally, in an active state, even if energy loss occurs due to a leakage or a half short circuit phenomenon of a power grid, it is left as it is. Before a dangerous situation occurs in which such energy loss exceeds a threshold value, abnormal symptoms such as a temperature rise, an increase in dissipated electrical power, etc. are presented. Thus, if the electrical abnormal symptoms are detected early, an electrical fire occurring in the line can be prevented. Also, the abnormal symptoms can be measured and quantified, and thus, can be used as an element for objectivizing safety of the line.

[0029] As a solution thereof, if electrical power loss between a power supply end and a power receiving end is measured in real time and is analyzed and processed (if it is processed through the following processing procedure), dangerous abnormal symptoms can be detected.

[0030] In a series network of Figure 2 , if a voltage (V S ) of the power supply end, a voltage (V L ) of the power receiving end, and a load current (I L ) are measured and are converted, line loss electrical power (P Ln , line loss electrical power), line resistance (R Ln ), load electrical power (P L ), load resistance (R L ), and total supply electrical power (P S ) can be obtained. Figure 3 It is shown that, when there is no leakage resistance (R FP ) in an equivalent circuit of a power grid modeled by Figure 2 , line loss electrical power (P Ln ) and line resistance (R Lntrends of the varying line loss electric power, the load power consumption, and the total power consumption.

[0031] If the dissipated electric power of the line exceeds a predetermined amount, a fire can occur. Therefore, if the electric power exceeds a set reference value, the supply of electric power to the load is cut off, thereby enabling a fire to be prevented. Even within the allowable current of the overload breaker 14, the dissipated electric power can be a cause of a fire. In this case, the maximum line loss electric power (P Ln ) can reach 25% (R L0 / R Ln = 1) of the load rated electric power (P L ). Therefore, even with the same line conditions, the greater the rated electric power of the load, the higher the risk.

[0032] 3. Line loss electric power measurement and deterioration abnormality sign detection

[0033] The line loss electric power is a direct cause of a line fire. The line loss electric power is caused by exceeding the allowable electric power or line deterioration (line defect) aging physical / chemical deformation, and the deteriorated portion generates relatively excessive joule heat. This heat can be a direct factor of a fire.

[0034] In the simple series network shown in FIG. 1, since the current at the power supply end and the current at the power receiving end are the same, the line loss electric power (P S ) can be found by measuring the voltage at the power supply end (V L ), the voltage at the power receiving end (V L ), and the load current (I Ln ) by the following equation (Equation 1).

[0035] P Ln = (V S - V L ) I L (Equation 1)

[0036] Here, P L0 : load rated electric power, R Lno : normal resistance of the line, R P : abnormal loss electric power occurring in the parasitic resistance (R Para , R FS ) of the line.

[0037] The abnormal electric power loss (P P ) is obtained by subtracting the normal line loss electric power (P Lno ) from the line loss electric power (P Ln ) (P P = P Ln - P LnO ).LnO Since the parasitic resistance is caused by a defect, the normal line loss power (P) LnO ) is usually a value that is almost close to 0, therefore it is

[0038] P LO In a load with rated power, according to the parasitic resistance (R) of the line P Increased load power (P) L ) and line loss power (P) Ln The trend is in Figure 3 , Figure 4 The relative power loss (P) is shown in the middle. Ln / P L0 When the line resistance (R) Ln =R Ln0 +R P ) and load resistance (R) L At the same time, the line loss power (P) Ln This results in the maximum power loss in the circuit.

[0039] Typically, when the line deteriorates, it becomes R. P >>R LnO The conditions for P are such that power loss also becomes a factor. P >>P LnO Parasitic resistance (P) Ln / P LO The power loss is concentrated in a localized area, and therefore varies depending on the relative power loss (P). Ln / P LO The heat generated is concentrated in the parasitic resistance (R). P This section is affected by power loss (P) in the line. Ln The heat is converted into Joule heat, so if the value exceeds a predetermined value, there is a possibility of fire. Therefore, if the value exceeds the predetermined value, the load needs to be cut off or subsequent measures need to be taken.

[0040] Here, even with the same power loss, the heat generation is concentrated in the deteriorated parts of the line, making it relatively more dangerous.

[0041] Figure 4 , Figure 6 This shows the relationship based on the line resistance (R) Ln =R LnO +R P The voltage drop across the changing lines, the load voltage, and the line loss power (P) Ln / P LO) between them. Symptoms of line deterioration are shown in the attached figures and the formula (Formula 5), and the change in line resistance is shown as an increase in line loss power and an increase in line voltage drop, and thus, if this is monitored, dangerous abnormality signs can be detected. Thus, these values (P P / P L0 , V P / V S ) can also be used as a scale index (Line Fault Index) indicating the degree of danger of the distribution line. As shown in the figure, since the values quantifying abnormality signs can be observed, if a predetermined value (Threshold) is exceeded, the load power needs to be cut off.

[0042]

[0043] 4. Line and Parasitic Resistance Measurement

[0044] It is important to understand the characteristics of the transmission path that has been established in the power grid. The line resistance serves as basic data that can be used not only for accident prevention dimensions, but also for analysis of deterioration factors or analysis of the trend / progress of deterioration, and a method for calculating the line resistance in the energized state is provided. In the following method, the calculation can be performed even in the online state, and thus the measurement values can be collected on the network.

[0045] If the voltage (V S ) at the supply end, the voltage (V L ) at the load end, and the load current (I L ) are measured and converted, the line resistance (R Ln ) of the line and the load resistance (RL) can be obtained. Figures 6 to 8 , Formula 2 shows the correlation between the relative voltage ratio (V L / V S ) at the supply end and the line resistance (R Ln ).

[0046] In the present invention, the line resistance can be calculated indirectly by measuring the voltage at the supply end, the voltage at the load end, and the line current. The line resistance (R Ln ) can be indirectly calculated by measuring the supply end voltage (V S ), the load end (load) voltage (V L ), and the load end (load) current (I L ) and converting using the following formula (Formula 2). In general, the normal line resistance (R LnO ) refers to the normal portion of the line resistance (R Ln ), and thus the abnormal line resistance (R P ) can also be considered as the total line resistance (R Ln ).

[0047]

[0048]

[0049]

[0050]

[0051] 5. Fire occurrence symptom detection and precautionary measures (prevention)

[0052] Electrical fires exhibit a variety of abnormal symptoms (Symptom) such as temperature rise, odor, flame, arc / spark, spark, increase in resistance of power line or increase in line loss power, increase in leakage current, etc. before the fire occurs. Among them, representative electrically detectable abnormal symptoms caused by defects in the line are as follows:

[0053] 1. Increase or instability in line resistance

[0054] 2. Increase (change) in line loss power

[0055] 3. Increase in line drop voltage

[0056] 4. Decrease in load voltage

[0057] 5. Increase in voltage change rate

[0058] 6. Increase in line leakage current

[0059] 7. Decrease in line insulation strength

[0060] 8. Decrease or instability in load current

[0061] 9. Increase in line temperature

[0062] 10. Occurrence of arc / tracking phenomenon

[0063] Figure 1 、 Figure 12 、 Figure 13 、 Figure 14 、 Figure 15 、 Figure 19 An example showing an embodiment of the technology of the present application is shown: a technology for detecting the occurrence of a fire in advance by monitoring the voltage drop or loss power between the two ends (power supply end - power receiving end) of the line that is easy to measure among the electrical abnormal symptoms of the power grid. An increase in the parasitic resistance of the power line appears as a change in the electrical energy loss (consumed power) on the line. Due to the increase in resistance at the electrical defect site, the voltage drop of the line and the increase in loss power.

[0064] If the voltage drop exceeds a predetermined limit, a fire can occur. Therefore, if the voltage drop is multiplied by the current, the line loss electric power can be obtained. If the electric power is supplied only within a safe range in which the loss electric power does not exceed a predetermined value (threshold value), an accident can be prevented. The electrical fire abnormality sign can be measured and quantified, and thus can be used in a fire prediction technique. Therefore, if a means for detecting and processing the electrical abnormality sign is provided, a prevention system for an electrical fire occurring on a line can be implemented.

[0065] Figure 10 A change in line loss electric power according to a change in line resistance under a predetermined load is shown. If the line resistance increases, the line loss electric power also shows an increasing tendency, and has a maximum value when it has the same value as the load resistance. At this time, the maximum loss electric power reaches 1 / 4 of the load rated electric power, and is the most dangerous condition.

[0066] Figure 10 、 Figure 11 It is shown that a parasitic resistance generated due to line deterioration can act as a current limiter that reduces a load current, and thus can prevent an overload breaker from exceeding a predetermined threshold value.

[0067] The present application can detect a sign of a fire accident that can occur on a line by measuring electric power lost in the line. This can prevent a fire occurring on a line by measuring a line voltage drop and a load current, and calculating a loss electric power, and cutting off the load current if it exceeds a threshold value. Also, if a line resistance value is converted to increase by more than a predetermined value, the same result can be obtained even if the load current is cut off. In the case of a stable voltage at a power supply end, only a voltage drop rate can be measured to simply achieve the intended purpose.

[0068] Preferably, if a green area of the safe operation region 110, 120 is departed, the load is disconnected.

[0069] Existing fire prevention is mainly implemented in a manner of detecting and cutting off an overcurrent, a leakage current, and an arc occurrence. However, this method is difficult to detect a fire occurring due to an increase in line resistance. That is, even under a normal load within an allowed electric power, a fire can occur due to deterioration of a line. A dotted line 160 is a region of excessive electric power loss in which a fire can occur, and if it enters the region, the supplied electric power needs to be immediately cut off.

[0070] The threshold value can be set in various ways.

[0071] 6. Maximum current measurement allowed on a line

[0072] Since line deterioration is a major cause of fires, if the resistance or maximum allowable current of the lines is calculated in advance to prevent fires, the available power can be calculated, which can then be used to construct a safe power grid.

[0073] The safe maximum current value of the line (maximum allowable current value, I) Lmax :) This can be achieved by measuring the power supply voltage (V) at the power supply terminal. S ), receiving terminal (load) voltage (V) L ) and load current (I L And apply the maximum allowable voltage drop rate (ε) O Use ) to perform the conversion.

[0074]

[0075]

[0076] Safe maximum current value (maximum allowable current, I) Lmax The power supply voltage, the receiving end (load) voltage, and the load resistance have the following relationship. This relationship can be calculated using the following formula (Equation 5). Lmax Maximum allowable current

[0077] R Ln =(V S -V L ) / I L

[0078] I max =V S (1-ε) / R Ln

[0079] ∴

[0080] 7. Detection of defects in power grids

[0081] The core principle of this electrical fire prevention technology is to detect line defects by measuring / analyzing the physical quantities of the line reflected by the electrical characteristics of the line caused by the current flowing in the line, and to find fire signs based on this.

[0082] like Figure 2 As shown, in order to detect defects in the lines that transmit electrical power in a circuit network, the line resistance (R) is used. Ln =R LnO +R P The changes in voltage at both ends of the line, load voltage, and line loss power (P) are reflected in the voltage drop, load voltage, and line loss power (P). Ln / P LO Changes in line conditions. Symptoms of line degradation include... Figure 3As shown, the change in line resistance presents the increase and decrease of line loss electric power and the abnormal sign of line voltage drop increase, thus the dangerous condition is predicted and detected by monitoring it. In the abnormal sign detection in the controller implementation, no matter selecting line loss electric power, line voltage drop, load voltage variation, line resistance or any physical quantity as the control variable, the expected purpose can be achieved.

[0083] As shown in Figure 10 , the abnormal sign quantity of power grid can be quantified and observed, thus if exceeding the predetermined threshold, the load electric power needs to be cut off. Here, the threshold 79 sometimes has a fixed value, if changing and dynamically setting according to the power supply time, input power voltage, type and characteristics of the load as needed, a more flexible and accurate system can be built. If it is developed, when the threshold 79 is changed and set by learning the characteristics of the load, a system more suitable for the situation can be built. In addition to the simple on / off mode, the cut-off or input of the load power supply can also consider the soft start mode, and can be applied to all electrical devices regardless of AC / DC.

[0084] Figure 1 , Figure 12 , Figure 13 An embodiment shown in the conceptual diagram of

[0085] 1. Supplying electric power to the load;

[0086] 2. Measuring the supply end voltage 11, the load end voltage 21 and the load current 23;

[0087] 3. Calculating the line voltage drop 45 by subtracting the load end voltage 21 from the supply end voltage 1;

[0088] 4. Calculating the line loss electric power 47 by multiplying the voltage drop by the load current 23;

[0089] 5. Comparing the line loss electric power 47 and the threshold 58;

[0090] 6. If the comparison result exceeds the threshold, cutting off the electric power supplied to the load and starting the protector.

[0091] The line loss electric power, which reflects the current flowing in the line and the electric characteristics of the line, is measured, and if it exceeds a certain value, it is judged to be a defect, and appropriate follow-up measures are taken. As a result, the threshold value becomes the maximum value of the line loss electric power allowed.

[0092] In the measurement of the physical quantity such as the line loss electric power, if the value of the measurement is integrated and the cumulative value is input as the basis for the judgment, or a filtering technique such as Moving Average Filtering is applied, noise and false operations against excessive phenomena can be minimized, and thus the reliability can be improved.

[0093] The embodiments are shown by the line loss electric power abnormality detection method, but can be more simply implemented by applying a method for comparison based on the line voltage drop between the power supply end and the power receiving end. In this case, there is a region that is sensitive to operation even if a small line electric power loss occurs under an extremely light load.

[0094] 8. Multiple accident loss electric power

[0095] Figure 10 、 Figure 11 The electric power loss in the transmission line according to the load variation within the trip current allowed by the overcurrent circuit breaker is shown. Figure 10 、 Figure 11 The line loss electric power that can occur on the line due to a fire that the overcurrent circuit breaker cannot detect is shown. That is, even if a dangerous situation occurs, the overcurrent circuit breaker cannot detect it. The maximum electric power loss that is lost within the trip current allowed by the overcurrent circuit breaker is as follows.

[0096]

[0097]

[0098] I Trip : Rated current of the overcurrent circuit breaker

[0099] In the case where the line resistance is the same as the V S / 2I Trip value, the electric power loss of V S I Trip / 2 [W] occurs on the line, and thus this is the most dangerous case (the case where the trip current is 200% of the rated current).

[0100] Existing overcurrent circuit breaker technologies for preventing electrical accidents prevent accidents caused by overcurrent by controlling the power supplied to the load by judging whether the load current exceeds the allowable limit value. However, they cannot prevent (detect) accidents caused by leakage short circuits (hereinafter referred to as "hard short circuits") or line defects within the rated range of the protector.

[0101] Existing protection technologies do not have mechanisms to detect whether they are operating appropriately based on the actual power supply capacity of the line. For example... Figure 10 , Figure 11 As shown, due to line deterioration, parasitic resistance may increase, or due to hard short circuits, accidents may occur.

[0102] The power loss of the circuit is directly converted into Joule heat. If it exceeds a predetermined value, it becomes a fire ignition condition, so necessary measures need to be taken (to minimize it). Here, the degradation of the circuit includes not only all electrical characteristics on the circuit itself, but also all electrical characteristics along the transmission path. That is, it can have various forms such as carbonization of electrical contacts and connections, incomplete connections, loose connections, contact resistance, physical deformation, partial breaks, and chemical corrosion. However, in this invention, these electrical characteristics are represented as parasitic resistance.

[0103] Electrical fires are caused by line deterioration and overcurrent. The main causes of fires in electrical circuits include changes in electrical characteristics such as increased parasitic resistance due to line deterioration (e.g., carbonization of electrical contacts and connections, incomplete connections, loose connections, contact resistance, physical deformation, partial breaks, and chemical corrosion). Increased line resistance leads to power loss when current flows, directly converting into Joule heat. If this resistance exceeds a predetermined value, it becomes a fire ignition condition. Therefore, it is necessary to minimize this resistance or detect its presence beforehand.

[0104] Since the parasitic resistance component, which is a cause of electrical fires, cannot be directly measured when energized, its presence (manifestation) can be derived or detected by indirect methods such as analyzing the power loss of the next electrical component, changes in line voltage drop, and arc energy spectrum in order to know its accurate value.

[0105] Because the resistive component in parasitic elements becomes Joule heated when current flows through them, circuit defects caused by an increase in this resistive component are detected. The deteriorating resistance of the circuit is concentrated in a physically specific location, and is therefore more dangerous than the dispersed resistance of a circuit with the same integer distribution.

[0106] The electric power loss on the line is manifested as an increase in electric power or voltage between both ends of the line. Before such energy loss exceeds a threshold value and a dangerous condition occurs, abnormal symptoms such as temperature rise, dissipated electric power increase, etc. are exhibited. The abnormal symptoms can be measured, and thus can be objectified or quantified, and if actually measured, can be used as a fire prevention technique. Therefore, if the electrical abnormal symptoms are detected early, an electrical fire occurring on the line can be prevented. The detection unit can be included in the electric power device and perform the detection all the time, but can also perform the detection as needed from the viewpoint of safety inspection.

[0107] As a solution thereto, if the electric power loss between the power supply end and the power receiving end is measured in real time and analyzed / processed (processed through the following processing procedure), dangerous abnormal symptoms can be detected, and thus accidents can be prevented.

[0108] The present application is basically a technique for measuring a physical quantity reflecting the electrical characteristics of a line in which a current flows due to a line connected between both ends, and analyzing the same to detect a defect in a series network composed of a power supply end (power source) 1 supplying electric power, a line transmitting electric power, and a power receiving end (load) 2 receiving electric power.

[0109] Line measurement techniques include a resistance meter, an impedance meter, an electric leakage meter, a phase difference meter, etc., but are not applied to a network in an energized state, and in order to cope with an unexpected emergency, the goal is to realize an optimized anti-electric disaster system capable of performing detection all the time.

[0110] 9. Line impedance measurer

[0111] In Figure 8 , the unknown line impedance of a predetermined transmission path in an energized electric power network can be measured. As shown in Equation 3, if the reference resistance is known, the internal impedance can be measured even without a current measurement unit. Figure 8 A network-based impedance measurer capable of measuring the line impedance and transmitting the measured value to the network to collect data is shown. This method can accurately know the characteristics of the reference resistance, and thus the measurement error is low, and thus accurate measurement can be performed.

[0112] By connecting a known reference resistance (R REF ) to the measured end after measuring the no-load voltage (V T1 ), and measuring the load voltage (V T2 ) to measure the change in the reference load and voltage, the internal synthesized impedance Z x is obtained, and if the absolute value and phase of the voltage are measured, the internal impedance can be obtained by one voltage measurement unit.

[0113] In a system having a power source inside, an unknown internal impedance can be measured. To this end, if a voltmeter and a known resistance are used, internal characteristics can be analyzed. First, a load is removed at a measured end, an open circuit voltage (V T1 ) is measured and stored, then a load is connected, a known reference resistance (R REF ) is connected to the measured end, after which a load voltage (V T2 ) is measured, and the internal impedance is calculated according to the equation of Equation 3. The relative ratio of the load voltage to the load voltage and the internal impedance are shown in Equation 4. Figure 7 By appropriately selecting the reference resistance, the resolution of the measurement can be improved.

[0114]

[0115] 10. Power grid defect detection mechanism

[0116] Figure 1 is a conceptual diagram of an electrical safety system for detecting abnormal signs of a disaster and preventing the disaster in a network connected with a power source, a transmission path, and a load.

[0117] To implement the power grid defect detection function, a voltage measurement unit for measuring the voltage of the power supply end and the power receiving end and a current measurement unit for measuring the current of the power supply end and the power receiving end are required.

[0118] A communication unit for exchanging messages between the power supply end and the receiving end, a data analysis unit, a calculation unit, a processing unit, and an output control unit are required. Since the power supply end and the power receiving end can be physically separated, a suitable message exchange unit is required. The transmission unit can be implemented using any of wired, optical communication, or wireless technology. The above-mentioned units, etc. can be implemented through Internet of Things technology.

[0119] The electrical characteristics of the defects can be measured by electrical methods. As a method of always monitoring the electrical defects of the power grid and automatically taking appropriate measures, the present invention can detect signs in advance before chronic static defects or progressive defects develop into an accident, thereby enabling prediction of the accident, and if measures are taken, the disaster can be prevented in advance. Also, arbitrary / occasional accidents such as hard short circuit (short circuit within trip current, electric shock), etc. that cannot be detected by existing protectors (circuit breaker, etc.) can be found early, thereby preventing the worst accident, and effective measures can be taken.

[0120] 10.1 Measurement of loss electric power of power grid

[0121] Figure 12is a system for measuring electric power loss in a transmission path and cutting off the supply of electric power to a line to prevent a disaster if the electric power is excessive. In an electric power system, in an electric power network 300 connected between a power supply end (superior node) 200 and a power receiving end (inferior node) 400, the input of the superior node is connected to a power source 1, the output 290 is connected to the input 390 of the inferior node 400 via the electric power network 300, and is equipped with a communication unit 500 for transmitting messages between the superior node 200 and the inferior node 400,

[0122] ① The input voltage 301 and the input current 203 are measured and integrated to obtain the supply electric power 215;

[0123] ② The inferior node 400 measures the load electric power (power receiving end electric power) 415;

[0124] ③ The superior node can receive the load electric power 403T of the inferior node and subtract the load electric power 403T from the own power source electric power 215 to obtain the dissipation electric power (205) in the transmission path; Figure 13

[0125] ④ The dissipation electric power 205 is an abnormal electric power caused by series and parallel defects 320, 330, 3 of the line of the transmission path, and the degree of aging of the transmission path can be known;

[0126] ⑤ The dissipation electric power is input to a comparator 206, and if it exceeds a threshold value (allowable value) 214 set in advance, a trip signal 209 is generated to cut off the supply of electric power, thereby preventing an accident in advance.

[0127] Here, in the case of a multiple load in which the number of loads is two or more, the load can be additionally connected to the power supply end 290. If all the load electric powers are subtracted in all steps ③, it can also be applied to an electric power network having a multiple load.

[0128] Figure 13 As an embodiment for measuring the dissipation electric power of an electric power network 300 having a multiple load, an electric power network configuration having one power source (power supply end) and n (n is a positive integer) loads (power receiving end) is shown. The power source section (V S ) 1 and the power source power meter composed of a voltmeter 301 and an ammeter are connected to the power source electric power meter, and all the load ends 2 (Load-1 to Load-n) are connected to the electric power measuring units 414-1 to 414-n, the arithmetic, communication, and control unit.

[0129] ​In a normal power network, the electric power supplied from a power source needs to be entirely transferred to a load end. In a normal case, the electric power supplied at the power source end and the load electric power add up to be equal. However, when the above two electric powers are not equal, this means that there is a leakage. In the present invention, even in an activated state, the dissipated electric power can be calculated by an indirect method. If the difference between the supplied electric power measured at the power source end and all the load electric powers measured in the load is found, the dissipated electric power caused by the leakage can be obtained. Therefore, all the loads need to be able to measure the electric power.

[0130] The dissipated electric power (Pdissipated) 215 can be measured by summing up the electric powers (P L1 , P L2 , P L3 ,... P L(n) ) measured at all the loads and subtracting the sum from the supplied electric power (Psupplied). S F

[0131] For the parallel defects such as a leakage, a short circuit, a ground, etc., the dissipated electric power caused by the series-parallel defects is measured by finding the difference between the supplied electric power and the actual electric power transferred to the load. The dissipated electric power 215 P is the difference in which the total supplied electric power at the power source end is subtracted by the sum of the electric powers measured at the respective loads, and can be expressed by the following equation. The dissipated electric power includes all the electric power losses occurring due to the series-parallel defects.

[0132]

[0133] Figure 13 A quantitative value (P F ) 215 of the abnormal loss electric power lost in the power network can be extracted. If the dissipated electric power increases beyond a threshold (shelf), an accident can develop. If the dissipated electric power exceeds the threshold, the supplied electric power is cut off at the power source supply end, so that an accident can be prevented or coped with at an early stage of the accident. Also, if the increasing tendency of the dissipated electric power 215 P is tracked, a sign of an accident can be detected.

[0134] Also, the quantitative value of the dissipated electric power has a functional relationship with the threshold 214 of the dangerous level and the dangerous index 217 can be obtained. Since the dangerous index can be quantified, a precautionary measure can be taken before an accident develops.

[0135] In the present embodiment, the quantitative value 215 P of the dissipated electric power of the power network can be extracted in real time, so that the integrity (defectlessness) of the line can be quantified. Also, if the maximum value is determined, the degree of danger can be quantified, so that the maintenance / repair information of the power network can be derived. ​​​

[0136] Measurement of dissipated electric power of power grid

[0137] In the present invention, dissipated electric power caused by all abnormal loads can be measured by the following method.

[0138] ① The power supply end supplies electric power to the load end through the power grid;

[0139] ② All load ends measure their own load electric power and send it to the power supply end (feedback);

[0140] ③ The power supply end totals the load electric power of all loads;

[0141] ④ The power supply end calculates the difference between the supply electric power to the load end and the total of the load electric power, and calculates the dissipated electric power (line loss electric power).

[0142] The dissipated electric power is generated not only due to the decrease in insulation strength, but also due to the line inherent resistance or parasitic resistance. Since the measurement result is all abnormal electric power except for normal loads, the measurement result can be used as basic data for preventing accidents or judging abnormal signs of the power grid. If the dissipated electric power increases, it can lead to an accident. In the present invention, since the quantitative value of the dissipated electric power can be known before the accident occurs, the progress of the electric leakage / short circuit accident can be known. That is, the abnormal signs of the accident caused by electric leakage can be quantitatively expressed. Also, although electric shock can be detected, the method cannot be designed to have higher sensitivity than the method of detecting by electric leakage current described below.

[0143] Also, if the data is systematically managed through the DB by continuously monitoring the consumed electric power, the history of the progressive accident of the electric leakage / short circuit accident can be tracked.

[0144] 10.2 Electric leakage / short circuit detection of live charging circuit - electric leakage current detection (electric shock detection)

[0145] Figure 14 The configuration of the power supply end 200 and the power receiving end 400 added for detecting defects and accidents on the line that can occur in the power system is shown. The detection principle is a method of calculating abnormal electric power by network analysis after measuring the dissipated electric power (dissipated electric power consumed in the transmission path) and the electric leakage current, the line voltage drop.

[0146] In a power system in which the power source 1 is connected to the input end of the superior node 200, the output 290 is added to the line 300 connected to the input end 390 of the inferior node 400 through the power grid, and the information transmission unit 500 is included between the superior node 200 and the inferior node 400,

[0147] ① The upper node (power supply end, power supply end) 200 measures the input voltage (power supply voltage) 1 and transmits it to the lower node (receiving end, load end) 400;

[0148] ② The lower node sends the power information (current 403, electric power) of the load to the upper node;

[0149] ③ The upper node receives the power supply current 403T of the lower node, subtracts it from its own power supply current 203, and thus measures the leakage current 205;

[0150] ④ Determine whether the leakage current exceeds the pre-set threshold (allowable value) 214, detect the defects 330, 3 of the transmission path;

[0151] ⑤ If the leakage current exceeds the pre-set threshold (allowable value) 414, all power supplies to the load are cut off by the load breaker 210, so that the development of an accident can be prevented;

[0152] ⑥ And, the degree to which the leakage current approaches the set threshold can be quantified to quantify the risk degree;

[0153] ⑦ The critical threshold is usually set to the maximum value that can be safely driven;

[0154] Here, in the case of multiple loads of two or more loads, it is configured that the load can be supplied via the power receiving end 400. If all load currents are summed in step ③, it can also be applied to a power grid with multiple loads. And, the series defect detection 310 of the line can be detected at the power receiving end 400 in the following method.

[0155] ⑧ The lower node receives the feeder voltage 203T of the upper node, subtracts its own voltage (load voltage) 401, and calculates the voltage drop (voltage difference) 405, i.e. the voltage drop reflecting the line characteristics; Here, since this voltage forms different paths when parallel defects occur, errors can occur, so there are some problems, but it is a useful method for detecting line defects.

[0156] ⑨ Determine whether the voltage drop 405 exceeds the pre-set threshold 414 of the voltage drop, detect the defects of the transmission path, and if a dangerous condition occurs, only the corresponding load can be removed from the load end 400 that exceeds the line capacity, so it will not affect the entire system, so it is useful.

[0157] 10.3 Detection and disaster prevention of insulation strength reduction, leakage, short circuit, and electric shock of multiple load power distribution power grid

[0158] Figure 13 、 Figure 15As an embodiment for detecting parallel defects of a power network, a power network configuration having one power source and n (n is a positive integer) loads is shown. The power source section 1 and all load terminals Load-1 ~ Load-n are equipped with voltage measuring units (voltmeters) 412-1 ~ 412-n and current measuring units (ammeters) 414-1 ~ 414-n.

[0159] The existing safety technology can easily detect unbalanced current leakage of a line, but balanced current leakage (inter-line short circuit) cannot be distinguished from normal load, and thus is difficult to detect.

[0160] Leakage detection between live lines can be achieved by disconnecting the power supply to all loads and measuring the power source current, but if the power supply to the loads is disconnected, not only will other problems arise, but it will also be difficult to detect progressive defects (leakage). Technology for measuring / detecting leakage in a live state in which electric power is supplied is very important. In a live state, the leakage detection technology can always be monitored, and thus is effective in terms of accident prevention.

[0161] In a power transmission line 5, 300, the characteristics of the line can be reflected by the load current for inherent line resistance and series defects FS201 such as poor connection, but in a live state, the leakage current caused by parallel defects FP204, FP206, FP208 crossing the line cannot directly measure the leakage current of the power supply to the load. In the present invention, the leakage current caused by the parallel defects can be calculated by an indirect method.

[0162] In a normal power network, the electric power supplied from the power source needs to be completely transferred to the load terminal. In a normal case, the sum of the load currents should be the same as the current supplied from the power source terminal when all the load currents are added. However, when the two currents are not identical, this means that there is a leakage current. The leakage current can be calculated by finding the difference between the supply current measured at the power source terminal and all the load currents measured at the load. Therefore, all normal loads must be able to measure the current.

[0163] If the currents (I L1 , I L2 , I L3 , … I Ln ) measured at all loads are summed and the sum is subtracted from the supply current (I S ), the leakage current (I FP ) can be measured.

[0164] For parallel defects such as leakage, short circuit, grounding, etc., the leakage current caused by the parallel defects can be measured by obtaining the difference between the supply current and the actual current transmitted to the load. The leakage current is the difference between the total supply electric power and the sum of the electric power measured by each load, which can be expressed by the following formula. The leakage current generated by the parallel defects is as follows.

[0165]

[0166] The present application can measure the leakage current caused by all abnormal loads by the following method.

[0167] ① The power supply end supplies electric power to the load end through the power grid;

[0168] ② All load ends measure their own load current and send it to the power supply end (feedback);

[0169] ③ The power supply end sums up the load currents of all the loads;

[0170] ④ The power supply end finds the difference between the supply current transmitted from the load end and the sum of the load currents, thereby finding the leakage current.

[0171] In this embodiment, the quantitative value of the leakage current of the power grid can be extracted in real time, so that the integrity (non-defectiveness) of the line can be quantified. Moreover, if the maximum limit is determined, the degree of danger can be quantified, thereby deriving the maintenance / repair information of the power grid. This current means that there is a parallel path (parallel defect) across the power line such as leakage. If the leakage current increases and exceeds (rests) the threshold value, it can develop into an accident. If the leakage exceeds the threshold value, the supply of electric power is cut off at the power supply end, thereby preventing accidents, or suppressing the accident at the early stage, and the increasing trend of the leakage current can be tracked, thereby detecting abnormal signs of accidents.

[0172] Moreover, the total leakage current 215 has a functional relationship with the threshold value 414 of the danger level, so that the dangerous index 227 can be obtained. Based on the dangerous index, preventive measures can be taken before the accident occurs.

[0173] 10.4 Leakage detection and non-grounded electric shock prevention of the power grid

[0174] The existing leakage cut-off technology is a technology for detecting leakage by detecting the unbalanced current between the lines, which is widely used as a means for preventing electric shock accidents. However, since the non-grounded leakage current between the charging part active lines cannot be distinguished from the normal load, protection cannot be performed.

[0175] The prior art is effective for grounding, but cannot detect non-grounding leakage, and thus has no special countermeasures for electric shock due to hard short circuit between active charging circuits. As described above, the current flowing due to a short circuit accident is not reflected as a load current because it cannot pass through the load current meter.

[0176] The present application can measure all leakage currents caused by abnormal loads including ground currents. If this method is used, non-grounding hard short circuit or electric shock between active charging circuits can be detected.

[0177] The current includes non-grounding leakage current due to a decrease in insulation strength between ground currents and active charging circuits, and electric shock current at the time of an electric shock accident, but series defects caused by parasitic resistance such as connection defects are hardly affected. Therefore, if the current is detected to be a predetermined value or more, a connection to an accident. In the present application, leakage current can be known before an accident occurs, so the duration of a leakage / short circuit accident can be known. That is, abnormal signs of an accident caused by leakage can be quantitatively detected. And the degree of approaching the preset threshold can be detected.

[0178] Also, in the present charging circuit leakage detection technology, if the critical threshold is variably set as needed when designing a safety circuit breaker, the sensitivity can be adjusted, so that the loss due to a mistake in a temporary power grid exposed to a construction site or the like where it is difficult to maintain the integrity of the power grid can be minimized. The sensitivity adjustment function can be useful in erecting a power grid if it is set to be higher at the initial stage of power supply and properly adjusted when the safety is confirmed. In addition, in the leakage detection method, the method of detecting leakage current is more sensitive than the method of detecting dissipated electric power, so that the loss at the time of a hard short circuit accident or electric shock can be minimized.

[0179] Advantages

[0180] The present application relates to a power grid line inspection (measurement) technology for detecting and preventing an accident occurring on a power transmission path or pre-identifying a weak bad line, differently from the existing overload monitoring overcurrent circuit breaker, and can prevent inappropriate use in advance or take a pre-emptive measure by pre-mastering weak information.

[0181] By measuring and analyzing the electrical characteristics of the line at all times in the power-on state, if the fire occurrence probability is high, the method of controlling (cutting off) the load to prevent fire, and the method of monitoring the line loss electric power of the transmission and distribution circuit in real time using the Internet of Things technology, as the loss electric power approaches the allowable value, a fire is prevented by an early measure (Alert).

[0182] By measuring the state of the line in advance, etc. to determine whether the line is normal or not, and database the maximum allowable current, a fire safety management can be enhanced and a systematic fire electrical fire prevention system can be provided. Since the database of the safety degree improvement information of the line can be realized, the risk degree / safety degree of the distribution line can be quantified. BRIEF DESCRIPTION OF DRAWINGS

[0183] Figure 1 : Conceptual diagram of the line defect detection system of the present invention

[0184] Figure 2 : Series-parallel defect modeling of a representative line with a parasitic resistance

[0185] Figure 3 : Effect of the parasitic resistance on the power grid

[0186] Figure 4 : Line loss electric power, load electric power, total consumed electric power, and line voltage drop according to line resistance variation

[0187] Figure 5 : Line loss electric power according to power grid deterioration

[0188] Figure 6 : Variation trend of the line loss electric power, load electric power, and total consumed electric power according to power grid deterioration

[0189] Figure 7 : Function of line voltage and line resistance (line resistance measurement)

[0190] Figure 8 : Conceptual diagram of remote line resistance measurement

[0191] Figure 9 : Function of line voltage and maximum allowable current (maximum allowable current measurement)

[0192] Figure 10 : Function correlation of line resistance increase and line loss electric power and protection area

[0193] Figure 11 : Protection / non-protection danger area when exceeding the rated load of the overcurrent circuit breaker

[0194] Figure 12 : Dissipated electric power measurement of the power grid

[0195] Figure 13 : Power consumption measurement of a multi-load electric power grid

[0196] Figure 14 : Electric leakage short circuit detection of a live charging circuit - electric leakage current detection (electric shock detection)

[0197] Figure 15 : Ground fault detection of a live charging circuit of a multi-load electrical power network

[0198] Figure 16 : Embodiment of protection mechanism of energy converter (transformer)

[0199] Figure 17 : Embodiment of line defect detector

[0200] Figure 18 : Operation diagram of associated control mechanism between control nodes

[0201] Figure 19 : Embodiment of line defect detector with single load

[0202] Figure 20 : Operation flow diagram of series defect detection of control nodes

[0203] Figure 21 : Structure of control nodes

[0204] Figure 22 : Embodiment of independent control system connected through IoT cloud network

[0205] Best mode for carrying out the invention

[0206] Figures 13 to 18 is an embodiment of a detector for detecting defects of an electrical power network in an electrical power control network in which electrical power (energy) is supplied in a subordinate (hierarchical) structure in the order of power supply (supply source) -> control node (upper) -> electrical power network (line) -> control node (lower) -> load (consumption end), each of the above-mentioned constituent elements is connected according to energy flow to function as a structure having both a power supply (input) and a load (output), and the lower node and the load are constituted as at least one.

[0207] Each control node is equipped with a measurement unit for measuring energy (electrical power information) passing through itself, a communication unit for exchanging messages between control nodes, and a control unit for control or alarm output, and each control node can communicate with each other and has a function of measuring and controlling energy (electrical power information) passing through itself.

[0208] The control nodes measure / monitor and control defects of the electrical power network by the following method to minimize disasters.

[0209] (1) The upper control node provides (feeds forward) its own electrical information (voltage) to the lower node;

[0210] (2) The lower node calculates the voltage difference from the upper node and controls the load according to the result thereof;

[0211] (3) All subordinate nodes measure energy (electric power and current) passing through or consumed by themselves and provide (feedback) the same to the superior node;

[0212] (4) The superior node sums all energy measurements passed to the plurality of subordinate nodes;

[0213] (5) The superior node calculates / comparisons energy (electric power, current) measurements of the subordinate nodes and energy (electric power, current) measurements passing through itself to derive a result (a step of finding energy (electric power, current) loss);

[0214] (6) An output control step of controlling output or passing to the outside according to the above-mentioned derived result;

[0215] Here, the control is performed by a method of comparing with a threshold value (a certain value set in advance) and cutting off the supply of energy to the subordinate nodes or sending an alarm according to the comparison result.

[0216] The defect of the power grid can be progressive or sudden (random). Especially, in the case of being progressive, an abnormal sign of the power grid can be detected by a method of observing the output change trend, so that a disaster can be predicted and pre-responded. That is, by pre-responding according to the detection result, the integrity of the power grid can be maintained to prevent a disaster in advance.

[0217] Node controller embodiment

[0218] constitutes the supply and distribution of energy in two or more remote points (nodes) connected by a power grid, and is a related mechanism physically separated into two or more but functionally coupled,

[0219] The power control device includes:

[0220] a measurement unit measuring its own voltage and power information (current or electric power) passing through (through) itself;

[0221] an output transmission unit transmitting the above-mentioned power information to the outside;

[0222] a calculation unit calculating a voltage difference from its own voltage and a voltage input from the outside;

[0223] a comparison unit comparing the above-mentioned voltage difference with the above-mentioned threshold value,

[0224] an external information collection unit collecting a plurality of external power information (electric power and current) and summing the same;

[0225] an output unit calculating or comparing its own power information and the above-mentioned collected external power information and outputting a control amount according to the calculation / comparison result,

[0226] wherein the above-mentioned power control device measures the dissipated electric power or leakage current of the power transmission network, thereby controlling the electric power output. DETAILED DESCRIPTION

[0227] 1. Embodiment

[0228] Figure 22 An embodiment of a protector for preventing accidents by monitoring a line voltage drop, a change in line loss electric power, and an excess of a limit value of load electric power as abnormal signs of line defects.

[0229] Initialization, setting of each threshold value 54, 56, 58 as a criterion for judgment;

[0230] 2. Measurement of no-load line voltage 21 and storage in virtual power source register 52;

[0231] 3. Supply of electric power to load 2;

[0232] 4. If the supply end voltage 11 is measurable, then the virtual power source register threshold value 52 is updated;

[0233] 5. Calculation of line voltage drop 45, and if it exceeds the threshold value 54, then the electric power supply to the load is cut off;

[0234] 6. Calculation of line loss electric power 47 by multiplying the above-mentioned voltage drop 45 by the load current 23-1;

[0235] 7. If the above-mentioned dissipated electric power 47 exceeds the electric power threshold value 56, then the electric power supply to the load is cut off, and the protector is activated;

[0236] 8. Calculation of load electric power 49 by multiplying the above-mentioned load voltage 21-1 by the load current 23-1;

[0237] 9. If the above-mentioned load electric power 49 exceeds the electric power threshold value 58, then the electric power supply to the load is cut off, and the protector is activated;

[0238] 10. Issuance of an alarm, and infinite repetition of measurement of physical quantities in which electric characteristics of the line caused by the current flowing in the line are reflected, and analysis thereof to detect defects, from the third step, and in order to prevent accidents that can occur in the line, if abnormal signs appear, then appropriate follow-up processing is performed.

[0239] Here, the follow-up measures can variably issue an alarm according to the degree of abnormal signs, can employ a method of cutting off the electric power supply, or can report the degree of line defects to a control system or personnel, so that analysis of defect causes, maintenance, and repair measures can be promptly taken.

[0240] In order to cope with a situation in which the system is confused due to a failure to acquire a power supply voltage as a control reference due to a communication problem or the like, the no-load voltage is treated as the power supply voltage during an initialization process. Thereafter, when the supply terminal voltage can be normally acquired, the actual power supply voltage is updated and treated.

[0241] Figure 1 、 Figure 12 is a conceptual diagram showing an embodiment of the operation principle of the present application. Although represented as a hardware circuit composed of various elements, most of the elements of the measurement unit and the control unit can be realized by a microprocessor and software.

[0242] The fire abnormality detection method of the present application has a method of detecting line loss electric power, an amount of accumulated loss energy, or a line voltage drop.

[0243] In addition to the above two voltage measurement units and one current measurement unit, in order to perform digital discrete processing, a communication unit for transmitting data obtained by an analog-digital converter (ADC) to a processing terminal is provided, whereby,

[0244] 1. A threshold value 58 that sets an allowable upper limit value of the loss electric power as a judgment reference for a dangerous situation is set;

[0245] 2. In order to measure the electric power of the supply terminal and the load terminal, the voltage and the current of both terminals are converted into digital data (A / D);

[0246] 3. The above digital-converted data is collected in a processing unit;

[0247] 4. The line loss electric power (line loss electric power) 47 is extracted by multiplying the voltage difference 45 of both terminals obtained by subtracting the voltage 21 of the load terminal from the voltage 11 of the supply terminal from the above current 23.

[0248] 5. The above line loss electric power 47 and a threshold value 58 set in advance are compared;

[0249] 6. If the above line loss electric power 47 exceeds the above threshold value 58, an abnormality of a fire is detected by a method of issuing an alarm or limiting the supply of dangerous electric power to the load (load terminal) 2, and an accident is prevented in advance.

[0250] A dynamic circuit breaker characterized by performing a method comprising the steps of:

[0251] (1) An allowable voltage drop rate is set;

[0252] (2) The supply of power to the load is cut off, the no-load line voltage is measured, and this value is stored as the supply voltage;

[0253] (3) calculating the above no-load line voltage and the above allowable voltage drop rate to set a threshold value;

[0254] (4) supplying electric power to the load;

[0255] (5) measuring a load voltage supplied to the load;

[0256] (6) comparing the load voltage with the threshold value;

[0257] (7) if the above comparison result is not lower than the threshold value, repeating from step (4), and if it is lower than the threshold value, detecting a defect of the line (change in electrical characteristics, exceeding of allowable current capacity due to deterioration) to cut off the load as a method of limiting the supply of electric power to the load.

[0258] In the fire prevention system equipped with the threshold value setting unit 54 capable of variably setting the load cut-off reference value 71, the power supply end always measures the supply voltage and always broadcasts to enable the power receiving end to know the above physical quantity 1, 13 of the power supply end, and if the external conduction signal 91 is input to the load, the control unit 40 makes the load control unit 24 conductive, so that before the electric power is supplied to the load 2, the process is performed in the following steps.

[0259] (1) if the control signal 99 for supplying the power source to the load 2 is input, the no-load voltage 21 of the load end 25 is measured and stored before the electric power is supplied to the load, and thereafter

[0260] (2) after the load control unit 24 is made conductive to supply the electric power to the load 2, the voltage and current of the line 3X are measured to monitor the degree of convergence to the threshold value set in advance.

[0261] Here, if the allowable maximum line voltage drop rate and the power source voltage are calculated and determined as a relative value according to the situation, the line defect detection threshold value can be dynamically and automatically determined even without being set to a specific value one by one, so that it can be dynamically applied to all loads regardless of the power source voltage and the load capacity, and thus it is more useful. However, since this is a prevention of defects on the electric power supply line, the electric power capacity of the breaker after the present technology is allowed to reach the maximum available capacity of the line, and thus in order to protect the load, it is preferable to use the maximum load current as the current threshold value. The threshold value of this value is the inherent electric power required by the load, and thus it cannot be automatically calculated.

[0262] The present invention is a technique for preventing problems occurring in a supply line, and goes beyond the field of detecting and preventing defects occurring inside all kinds of loads. However, since the load current / power is measured, the same as the existing method, a method of setting a threshold value that determines the upper limit of the load current and cutting off the overload in combination or cutting off the load power based on the load power is also provided.

[0263] (3) Measuring the load voltage 21 and current 23 supplied to the load;

[0264] The present invention detects line abnormalities by the following four methods, and if one or more are detected, it is judged that there is a line problem and subsequent measures are taken. The detection can be performed by various methods.

[0265] (a) Loss power of the transmission line;

[0266] (b) Loss power of the transmission line (sectional cumulative power loss)

[0267] (c) Voltage drop of the transmission line;

[0268] (d) Impedance of the transmission line;

[0269] (4) Measuring the supply end voltage 1 and transmitting it to the control unit 40, and if the control unit receives normal data, multiplying it by the allowable voltage variation rate 54 and updating the threshold value stored in RDmax 54 as a judgment reference value;

[0270] (5) Calculating the line voltage drop 31, 45 from the supply voltage 1 of the supply end 11 (or the above-mentioned stored no-load voltage 21 and the current load voltage 21-1) and comparing it with the threshold value 71 set in advance, and if it is lower than the threshold value, judging that there is a defect in the line and cutting off or detecting the power supplied to the load 2.

[0271] (6) Calculating the line loss power 85 from the above-mentioned supply end 11 supply voltage 1 (or the above-mentioned stored no-load voltage 21 and the current load voltage 21-1) and multiplying it by the load current 22 to calculate the loss power 85 lost in the line;

[0272] (7) By comparing the above-mentioned line loss power 65 with the threshold value 74 set in advance, if it exceeds the threshold value and is judged to be a defect in the line, preventing accidents by cutting off the power supplied to the load 2 or a method of notifying.

[0273] 2. Example 2

[0274] Since it is difficult to obtain the supply end power voltage at a remote place, the simple implementation of the independent model processes the no-load voltage as the power voltage in the initialization process.

[0275] To solve the problem occurring in the independent method, if the first tripping condition occurs, to confirm the error caused by the change in the condition of the power supply end, temporarily change to the no-load state of cutting off the load for a short time, and measure the no-load voltage, recheck the stability of the voltage of the power supply end, so that in the case where the tripping signal is not caused by power supply voltage fluctuation, the conclusion is that the line is defective, otherwise, in the case where the cause is power supply voltage fluctuation, the no-load voltage value is updated, and the initial power supply step is re-executed, thereby preventing misoperation and further preventing reliability reduction. Thereafter, under the same load, the data learned through the above steps can also be reflected in the threshold setting. That is, the change pattern of the learned load current is analyzed, and the threshold suitable for the load condition is derived, and dynamically changed according to the pattern of the load current.

[0276] To find the loss electric power in a single series line connecting the power supply end and the power receiving end, measure the voltage and current at both ends and calculate the electric power, so that the loss electric power of the line can be found by P Ln (i) = P S -P L (i) relationship to find the loss electric power of the line.

[0277] Figure 1 、 Figure 12 An example of installing a defect detection and control device in the power receiving end in the present invention is shown.

[0278] P Ln (i) = P S -P L (i)

[0279] P Ln (i) = P S -P L (i)

[0280] If the power supply end voltage, the power receiving end voltage, and the load current (which are basically related to the line loss electric power) are measured and calculated, the line loss electric power can be calculated. However, in the case where the power supply end and the power receiving end (load) are physically separated, a new additional line is required. Therefore, it is not realistic to add an additional line in order to apply this principle, and therefore the practicality is low. However, the recent development of wireless communication technology can easily solve this problem. As a technology with high reality, if wireless IoT technology is used, a disaster prevention system with high practicality can be realized. (Basic principle represented by the following equation)

[0281] Even if the real-time power supply voltage 1 of the power supply end cannot be measured or transmission errors occur between the power supply front ends, it is necessary to be able to independently (automatically, Stand-alone) perform the basic function.

[0282] To this end, the no-load line voltage V L0The voltage at the power supply terminal 1, 15 is regarded as the supply terminal voltage 1, 15 and treated as a reference value until a change occurs and a new value is updated. If the load is turned on, the above-mentioned no-load line voltage V L0 The voltage before the turn-on is maintained, and if the load is turned off, the above-mentioned no-load line voltage V L0 This value is updated in real time.

[0283] However, this method is erroneous in the case where the voltage at the power supply terminal 11 changes. In the activated state of the load, it is not possible to accurately know whether the cause is a change in the supply terminal voltage or a change in the line characteristics, thus some problems are accompanied. In the case where the change in the supply terminal voltage 1 is severe, it is not possible to perform an accurate operation, but in the case where the supply terminal power is stable, since the external measuring unit 10 and the communication units 34, 36 for measuring the supply terminal voltage are not used, the structure is simple. The following equation supports the above-mentioned explanation.

[0284] P Ln (i) = P S - P L (i) = (V S - V L (f)) · I L (i) = V Ln (i) · I L (i)

[0285]

[0286] V Li | I Li = 0 = V S : pseudo power supply voltage

[0287] In order to prevent an operation sensitive to noise or inrush current, heat generated due to line electric power loss can also be used as a reference value for the judgment.

[0288]

[0289] The above-mentioned approximate equation has an increased error in the case where the capacity of the power supply terminal is insufficient or the change in the supply voltage is severe, but actually V Li (0) is a physical quantity that can be obtained in the no-load state where the power supply terminal and the load are removed from the power distribution network, thus the practicality is high.

[0290] In addition, the loss electric power of the line series power distribution network is proportional to the voltage drop at both ends, so even without a current measurement unit, a line defect can be detected, and even if the change ratio of the supply voltage and the load voltage is measured, a line defect can be detected. In this case, since all line impedances (resistances) are cumulatively summed, information between specific sections cannot be obtained, so it can be inaccurate, and it can be misjudged, but it is possible to prevent an accident that exceeds the allowable capacity due to the addition of a load on the series power distribution path.

[0291] 4. Embodiment - Energy converter protection

[0292] The basic concept of the present application can also be applied to the safety management of energy converters such as transformers in power grids. That is, the electric power lost in the transformer can be measured in real time, so that safety operation information can be obtained, and dangerous level information can be obtained, so that accidents such as explosions can be prevented.

[0293] Figure 16 is realized based on the concept of detecting defects by detecting energy loss of a power system, and can be applied to all fields of energy transmission and conversion. For example, the main causes of accidents such as power converters such as transformers 810, inverters, etc. are analyzed as interlayer short circuits 812, 814, overheating, deterioration of insulating oil, connection defects, overload, etc. This is a way of detecting whether a physical quantity related to the above causes exceeds a threshold value and taking appropriate measures. However, in the above method, the maximum allowable electric power decreases due to aging changes due to external conditions and aging / deterioration, etc. In the present embodiment, in order to minimize such a problem, if the limit electric power 214 is set with the efficiency of the converter and the loss electric power 205, the safe operation can be appropriately performed according to the aging. Also, an example of overheat detection 820 which is a symptom of deterioration of the transducer 810 is shown. If the state is appropriately reflected and monitored remotely by IoT technology, appropriate operation can be performed without using a complex additional sensor. If the disaster prevention / monitoring system of the present application is linked with smart grid technology, it has a structure that can easily perform remote management in a cheaper and simpler method than the existing method. Examples of appropriate tripping conditions according to the degree of deterioration are shown below.

[0294] Conversion efficiency:

[0295] Loss electric power: ΔP = P1 - P2

[0296] Maximum allowable electric power loss rate: p TH

[0297]

[0298] As the communication unit 500 between the input and the output, the energy converter 802 can employ any unit such as RF, electromagnetic coupling, optical communication, etc. according to the need for electrical insulation between the input and the output, but the input and the output of the energy converter such as a transformer are close to each other, and high insulation withstand voltage is required, and therefore, in consideration of EMI, etc., the optical fiber optical communication is advantageous.

[0299] 5. Power Control Domain

[0300] The power node (power bridge controller) as a control unit that receives an electric power supply (input) from a power source (superordinate power grid) and distributes electric power to a load (subordinate power grid), measures electrical information of an electric power transmission line and controls the electric power supply according to the state. The power grid has a hierarchical structure, and has a hierarchical tree topology in which the form of superordinate node-power grid-subordinate node is repeated. The physical branch without a node (bridge) of the present invention is logically considered to be the same layer.

[0301] The layer division is effective when becoming a control object of the present node. If a subordinate node is added to the power grid managed by the node, its subordinate node is considered as one load. Generally, the power grid is physically in the form of a mesh, a multi-point bus, or a tree. In the present invention, the layer and the branch are classified with the control node as a reference.

[0302] In the present invention of Figure 17 , the power control domain (power segment plane, power class) Figure 17 is a power grid unit that is separated (independent object) from other power grids regardless of the supply and demand of energy, with a detection area and a protection control mechanism, etc., in a power system having one power source 1 (supply end, input) and one or more loads (power receiving end, output), and generally, the power grid is expanded in a hierarchical structure, and therefore, although it is the same layer (layer) in terms of the power source, in a power system having one power source (supply end, input) and one or more loads (power receiving end, output) that can be controlled and monitored using a control area and an electrically / logically related area, a detection area and a protection control mechanism, etc. are defined as a power grid unit that is separated (independent object) from other power grids regardless of the supply of energy.

[0303] The control nodes 200, 400, 600 receive electric power from the superior node and directly transfer the electric power to the inferior load. Control and measurement can be performed only in one step up and down. However, when obtaining a measurement value of a supply voltage, if communication with its own supply control node (n-1 layer) is not smooth, the control range can be expanded by obtaining a measurement value from the superior node 200 (n-2) having a higher level. Here, the nodes 200, 400, 600 are capable of transmitting electric power and capable of message exchange with a node having a means capable of measuring the above-mentioned voltage, current, electric power and capable of controlling output. The gateway node 400 is a node 400 having a function of receiving electric power from a superior node having a function of a power supply terminal and a power receiving terminal and transferring to an inferior node or domain (Domain), and controlling electric power supply to the inferior node 600 if necessary.

[0304] With the supply and detection / control domain of the power source, the inferior power grid is expanded in a hierarchical structure, and thus has an influence on the flow of electric power transmission. In all power planes (Power Plane), the superior plane (Plane) with respect to itself is regarded as a power source and receives power supply, and the inferior plane (Plane) 600, 600-2, 600-3 is regarded as a load and supplies electric power. Control and measurement are effective only for the load of the same domain, and electric power information of the superior domain or the inferior domain of two stages or more than two stages other than the neighbor of the same level is not an object of determination.

[0305] 6. Smart Grid linkage

[0306] Figure 22 A management system of a power grid to which an IoT technology is applied is shown. Among physical quantities measurable in the system of the present invention, line voltage drop V Ln , line loss electric power P Ln , line resistance R L , and maximum allowable current I Ln(max) are electrical data that can determine abnormal signs of an accident, and are information directly related to the accident, and thus need to be monitored at all times if one of them exceeds the allowable range. Among them, the line resistance R L , the maximum allowable current I Ln(max) , and the line equipment are related, and need to be grasped and maintained in advance, and the dynamic measurement technology of the present invention does not cut off the electric power supply of the line, and can estimate the line resistance R L and the maximum allowable current I Ln(max) in an energized state by an indirect method even without using a special measuring instrument.

[0307] A commercial power distribution grid connected like an actual spider web, as long as the line resistance RL and the maximum allowable current I Ln(max) line information and database (DB) and the line supply voltage V S , load voltage V L , load current I L , load electric power P L , real-time measurement information analysis management, it is possible to construct a system that can innovatively reduce accidents caused by lines. If the information of the power distribution network is collected in real time, the network state DB of the line safety, the maximum allowable current I Ln(max) , electric power loss PLn, etc. can be established, and it is possible to take preventive measures such as failure prevention, thereby providing maintenance / repair information.

[0308] For the power grid defect detection technology, since the real-time electric power, supply amount, and even the state of the power grid can be known by combining existing IoT technology and other information communication technologies, it is possible to realize a power grid safety map. By constructing a social safety network using technology, it is possible to detect electrical accidents in advance, thereby maximizing the safety.

[0309] For the extracted line information, if the information analyzed and processed based on a more developed method of analyzing the cause of an electrical fire or early detection of line degradation through loss electric power recording and analysis is applied to a multi-path power distribution network and data is collected / analyzed, it is possible to derive quantitative information (risk degree index, safety index) about the safety of the power grid.

[0310] If the information such as the number of warning occurrences, repair information, line connection points, branch lines, and location / address is combined, in line management, not only the location information of the node and the accident situation can be displayed on the map as line danger information (safety degree), but also the electric power supply state can be displayed, thereby enabling intuitive confirmation, and thus it is more useful.

[0311] The above safety degree-map displays the safety degree on the map considering the voltage drop V Ln , line loss electric power P Ln , line resistance R Ln , and maximum allowable current I Ln(max) , and compares the line supply voltage V S , load voltage V L , load current I L , and load electric power P L, if the predetermined value is exceeded, an alarm is issued and reported to the power grid control center. The user is notified through an alarm or an SMS message. If the risk index is high and judged to be serious, the power supply to the load is immediately cut off, thereby enabling most line accidents to be prevented, however, while the above method is appropriate in the case of overload, since accidents caused by line deterioration can be identified in advance, if they can be dealt with in advance by advance warning, it can become a more practical system. By setting the threshold to multiple levels and warning according to the risk level, a more practical system can be constructed.

[0312] Connection with the smart grid can be achieved by connecting to the Internet cloud via the gateway 300 using an IoT technology that has been commercialized. Monitoring data on a plurality of line information can be transmitted from a separate power grid information collection device included in the gateway. Here, the Internet can be any one of wired / wireless communication networks that provide communication of various information devices within a limited area, or can be a combination of two or more. In addition, the transmission scheme standard of the network corresponding to the Internet is not limited to the existing transmission scheme standard, and all transmission scheme standards developed in the future need to be applied.

[0313] Also, if the power grid line information collected through the power grid line diagnosis technology of the present application is systematically stored in a DB through an IoT gateway and associated with big data technology, innovative development will also be made in terms of accident signs and accident cause analysis, and a more useful power grid management smart grid technology can be achieved.

[0314] Since the power grid control center can grasp the power line status in real time, it can detect power grid defects caused by line defects and overload, thereby enabling maintenance / repair information to be obtained in advance, and further enabling faults to be prevented.

[0315] Since excessive power loss of the power grid directly indicates an accident, the risk level can be quantified, thereby enabling the risk level to be reflected as a determining factor of the objective safety level index.

[0316] 10. Investigation

[0317] The present application prevents accidents in advance by detecting electrical defects of the power grid and abnormal signs of the line and taking appropriate advance measures. It is designed to operate in a basically independent mode in response to a situation in which there is a problem in the communication network.

[0318] Electrical defects are continuously monitored and line defects are automatically detected regardless of external conditions such as power supply voltage.

[0319] The line defect detector of the present application is substantially independent of the physical location of the line, and thus detects a line defect between a measurement point (power supply end) and a power receiving end (load) regardless of the location. The defect is detected as an abnormality in the form of an increase in voltage drop or an increase in line loss power and leakage current.

[0320] An electrical defect can occur at any location in the power grid. Thus, if the line defect detector is densely arranged, the defect cause can be found more effectively. In this case, each node informs an external control center or a node in the periphery of information measured by itself and control information, and thus a more effective and fine safety network can be constructed. However, the node system of the present application can be constructed to have a correlation, but can also be implemented as an extension structure in which each node operates independently (stand-alone) without adversely affecting each other. By receiving information from a related node and processing only data related to itself, the flexibility in constructing a network is high, and thus is not limited.

[0321] In a case where the measured value of each measurement unit and a value calculated based on this according to a processing / verification algorithm exceeds a pre-set normal range, the control device determines that an error has occurred in one or more of exceeding the line allowable current capacity or exceeding the current capacity overload, and takes a subsequent measure. Each measurement and processing of this step is preferably processed in real time in parallel using an interrupt technique in synchronization, and thus the precision can be improved.

[0322] The subsequent measure can issue an alarm by stages according to the degree of exceeding the reference value range, and can send a degree of danger of cutting off the supply of electric power to a load as a cause thereof to a management center according to the number of alarms and the degree of danger, and thus a danger map or the like can be constructed based on a database, and further various measures can be taken, and can function as a main constituent element in a regulatory control network as a node of a smart grid or the like using IoT technology.

[0323] If the defect state is removed, the error detection loop is recycled by closing the contact again, and thus the interrupted circuit is restored to power.

[0324] The technology of the present application can be applied to all electrical systems regardless of AC / DC, and can be applied to a transformer, a power inverter, a solar power generation system, an ESS, and the like in various forms.

[0325] The inventive concept is not limited to the examples in the specification and can be reflected in various forms and implemented with various modifications, substitutions, changes and equivalents. The embodiments are provided as examples to sufficiently convey the inventive concept to those skilled in the art with ordinary knowledge. The principles of the present invention are not limited to the above-described embodiments, but can be embodied and modified in other forms. Although the above description includes a large number of features, these features are intended to facilitate explanation, and should not be interpreted as limiting the scope of the present invention.

[0326] Industrial applicability

[0327] Since the pre-safety technology can effectively reduce the social rate of loss of life and property caused by electrical fires, commercialization is expected, and the growth of demand for safety-related smart device components / products industries based on the Internet of Things and the simultaneous growth of measurement technology-related industries based on the Internet of Things are expected.

Claims

1. An electric power control system for electric appliance disaster pre-detection and prevention, characterized by, including: a power supply end that supplies electric power; a power receiving end that receives electric power from the power supply end through a line; and a power control device that calculates at least one of a loss power value, a leakage current value, a voltage drop value, and an impedance value based on voltage values and current values measured for the power supply end and the power receiving end respectively, compares the calculated at least one calculated value with a pre-set threshold value corresponding to each of the calculated values respectively, confirms a change in an electric characteristic, thereby detecting whether the line is abnormal, and controls electric power supplied to the power receiving end if it is detected that the line is abnormal, the power control device variably sets and applies a pre-set threshold value corresponding to each of allowable values dynamically, taking into account the allowable values, and sets the pre-set threshold value in a plurality of stages, and according to a degree of danger corresponding to each of the stages, issues a warning by stage, or controls electric power supplied to the power receiving end.

2. The power control system according to claim 1, wherein the power control device includes: a higher control node that obtains a supply voltage value, a supply current value, and a supply power value from voltage values and current values with respect to the power supply end and transmits them to a lower control node; the lower control node that measures voltage values and current values with respect to the power receiving end, obtains a load voltage value, a load current value, and a load power value and transmits them to the higher control node.

3. The power control system according to claim 2, wherein the higher control node, if it receives the load power value from the lower control node, calculates a difference between the supply power value and the load power value as a loss power value, compares the loss power value with a pre-set power threshold value, and then decides whether to cut off electric power supplied to the power receiving end according to a result of the comparison.

4. The power control system according to claim 2, wherein the higher control node, if it receives the load current value from the lower control node, calculates a difference between the supply current value and the load current value as a leakage current value, compares the leakage current value with a pre-set current threshold value, and then decides whether to cut off electric power supplied to the power receiving end according to a result of the comparison.

5. The power control system according to claim 2, wherein in a case where the power receiving end is a plurality of power receiving ends, the lower control node is provided as a plurality of lower control nodes in a manner corresponding to the plurality of power receiving ends respectively, in a case where the lower control nodes are a plurality of lower control nodes, the higher control node, if it receives the load power value from each of the plurality of lower control nodes, calculates the loss power value using a sum value obtained by adding each of the received load power values, the higher control node, if it receives the load current value from each of the plurality of lower control nodes, calculates the leakage current value using a sum value obtained by adding each of the received load current values.

6. The power control system according to claim 5, wherein The lower control node calculates a value obtained by subtracting the load voltage value from the supply voltage value received from the upper control node as a voltage drop value, compares the voltage drop value with a pre-set voltage drop threshold value, and decides whether to cut off the power supplied from the supply end based on the result of the comparison.

7. The power control system according to claim 6, wherein The power control device controls to cut off the power only to the power receiving end whose voltage drop value exceeds the pre-set voltage drop threshold value, in a case where a plurality of power receiving ends are provided.

8. The power control system according to claim 2, wherein The upper control node, if receiving the load voltage value and the load current value from the lower control node, calculates a value obtained by subtracting the load voltage value from the supply voltage value as a voltage drop value, calculates the voltage drop value multiplied by the load current value as the loss power value, compares the loss power value with a pre-set power threshold value, and then decides whether to cut off the power supplied to the power receiving end based on the result of the comparison.

9. The power control system according to claim 4, wherein The pre-set current threshold value is a maximum current allowable value, The maximum current allowable value is calculated based on mathematical expression 1, [mathematical expression 1] ， wherein, represents a maximum current allowable value, represents a supply voltage of the power supply end, i.e., a supply voltage value, represents a load voltage of the power receiving end, i.e., a load voltage value, represents a load current, i.e., a load current value, R Ln represents a line resistance, R L represents a load resistance, represents an allowable voltage drop rate.

10. An electric power control device for early detection and prevention of electric appliance disaster, characterized by, comprises: a communication unit; a measurement unit that measures voltage values and current values of each of a supply end that supplies power and a power receiving end that receives power from the supply end through a line; a calculation unit that calculates at least one of a loss power value, a leakage current value, a voltage drop value, and an impedance value based on the voltage values and the current values measured for each of the supply end and the power receiving end, compares the calculated at least one calculated value with a pre-set threshold value corresponding to each, and confirms a change in an electrical characteristic to detect whether the line is abnormal; and a control unit that controls power supplied to the power receiving end according to the detection result of the calculation unit, wherein the control unit is configured to treat an open-circuit voltage of the power receiving end as a voltage of the supply end when it is difficult to obtain the voltage of the supply end, control power supply of the supply end when the loss power value and the leakage current value between the supply end and the power receiving end exceed a threshold value, control power supply of the power receiving end when the voltage drop value exceeds a threshold value, and the control unit sets the pre-set threshold value in multiple stages, and issues an alarm or controls the power supplied to the power receiving end according to a degree of danger corresponding to each stage.

11. The power control device according to claim 10, wherein The measurement unit obtains a supply voltage value, a supply current value, and a supply power value from the voltage value and the current value of the supply end, and obtains a load voltage value, a load current value, and a load power value from the voltage value and the current value of the power receiving end.

12. The power control device according to claim 11, wherein the computing unit calculates a difference between the supply power value and the load power value as the loss power value, compares the loss power value with a pre-set power threshold, and then detects whether the line is abnormal based on a result of the comparison, in a case where the power receiving ends are plural, an added value is calculated by adding the load power values of the respective power receiving ends, a difference between the supply power value and the added value is calculated as the loss power value, and the loss power value is compared with a pre-set power threshold, and then whether the line is abnormal is detected based on a result of the comparison.

13. The power control device according to claim 11, wherein the computing unit calculates a difference between the supply current value and the load current value as the leakage current value, compares the leakage current with a pre-set current threshold, and then detects whether the line is abnormal based on a result of the comparison, in a case where the power receiving ends are plural, an added value is calculated by adding the load current values of the respective power receiving ends, a difference between the supply current value and the added value is calculated as the leakage current value, and the leakage current value is compared with a pre-set current threshold, and then whether the line is abnormal is detected based on a result of the comparison.

14. The power control device according to claim 11, wherein the computing unit calculates a value obtained by subtracting the load voltage value from the supply voltage value as a voltage drop value, compares the voltage drop value with a pre-set voltage drop threshold, and decides whether to cut off the power supplied from the power supply end based on a result of the comparison, in a case where the power receiving ends are plural, the control unit controls to cut off the power only to the power receiving end whose voltage drop value exceeds the pre-set voltage drop threshold.

15. A power control method, performed by a power control system, for electrical appliance disaster pre-detection and prevention, characterized by, comprising the steps of: measuring voltage values and current values of a power supply end which supplies power and a power receiving end which receives power from the power supply end through a line, respectively; calculating, by a power control device in the power control system, at least one of a loss power value, a leakage current value, a voltage drop value, and an impedance value based on the voltage values and the current values measured for each of the power supply end and the power receiving end; confirming a change in an electrical characteristic by the power control device by comparing the calculated at least one calculated value with a pre-set threshold value corresponding thereto, respectively; detecting, by the power control device, whether the line is abnormal based on a result of the confirmation; and controlling, by the power control device, the power supplied to the power receiving end if it is detected that the line is abnormal, wherein the pre-set threshold value is set in a plurality of stages, in the measuring step, a supply voltage value, a supply current value, and a supply power value are obtained from the voltage values and the current values of the power supply end, and a load voltage value, a load current value, and a load power value are obtained from the voltage values and the current values of the power receiving end, in the controlling step, an alarm is issued or the power supplied to the power receiving end is controlled by stage according to a degree of danger corresponding to the respective stages.

16. The power control method according to claim 15, wherein, in the step of performing the confirmation, a difference between the supply power value and the load power value is calculated as the loss power value, and the loss power value is compared with a predetermined power threshold value, in a case where the power receiving ends are plural, a sum value is calculated by adding the load power values of the respective power receiving ends, a difference between the supply power value and the sum value is calculated as the loss power value, and the loss power value is compared with a predetermined power threshold value.

17. The power control method according to claim 15, wherein, in the step of performing the confirmation, a difference between the supply current value and the load current value is calculated as the leakage current value, and the leakage current value is compared with a predetermined current threshold value, in a case where the power receiving ends are plural, a sum value is calculated by adding the load current values of the respective power receiving ends, a difference between the supply current value and the sum value is calculated as the leakage current value, and the leakage current value is compared with a predetermined current threshold value.

18. The power control method according to claim 15, wherein, in the step of performing the confirmation, a value obtained by subtracting the load voltage value from the supply voltage value is calculated as a voltage drop value, the voltage drop value is compared with a predetermined voltage drop threshold value, and it is determined whether to cut off the power supplied from the power supply end based on the comparison result, in the step of performing the control, in a case where the power receiving ends are plural, the control is performed so as to cut off the power only to the power receiving end whose voltage drop value exceeds the predetermined voltage drop threshold value.

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