Predictive Heat-Trace Control Method and System for Road De-Icing Using a Thyristor Power Regulator

Abstract

The present invention relates to a prediction-based heating wire drive control method and system for preventing freezing of roads and bridges during winter. The system according to the present invention collects meteorological information such as temperature (T), humidity (RH), wind speed (V), precipitation (R), and snow depth (S), as well as data such as ambient temperature (Ta) and road surface temperature (Ts) in real time, calculates the dew point (Td) and freezing risk index (Ir), and optimizes the output (u) of the heating wire by performing a Model Predictive Control (MPC) algorithm based on these values. The objective function of predictive control is configured to minimize the error between the road surface temperature and the target temperature, power consumption, and output fluctuation rate, and the current applied to the heating wire is continuously varied using a Thyristor Power Regulator (TPR). In addition, by combining feedforward and feedback control, it is possible to maintain stable road surface temperatures even in situations of rapid weather change, and it includes a scheduling control function that compares freezing risk indices for multiple heating cable sections to assign priorities and distribute loads within the power feeder capacity. In addition, in the event of a sensor malfunction or communication failure, the local fail-safe control logic operates to perform step-by-step safety outputs based on the ambient temperature, thereby maintaining the anti-freezing function. Accordingly, the present invention provides an intelligent road anti-icing heating cable control technology that simultaneously achieves energy saving, prevention of overheating, protection of structures, and improved control reliability in a road anti-icing system.

Description

Technology Field

[0001] The present invention relates to a heating wire drive control technology for preventing road surface freezing of roads and bridges during winter. More specifically, the invention relates to an intelligent power control technology that predicts the possibility of freezing in advance by comprehensively analyzing weather information such as temperature, humidity, wind speed, precipitation, and snowfall, as well as road surface condition data such as ambient temperature, road surface temperature, and water film condition, and precisely controls the applied power of the heating wire using a Thyristor Power Regulator (TPR) according to the prediction result, thereby stably preventing freezing of roads and bridges while minimizing energy consumption, and simultaneously preventing damage to the road surface pavement layer or thermal deformation of the bridge deck caused by overheating of the heating wire. Background Technology

[0002] During the winter, as outside temperatures drop sharply, road and bridge surfaces freeze, leading to frequent traffic accidents such as skidding and chain collisions.

[0003] To prevent such problems, road de-icing systems that generate heat by embedding heat traces in road surfaces or bridge decks and passing an electric current through them are widely used.

[0004] However, since most conventional systems use a simple ON / OFF control method based on temperature detection, they have a simple structure in which the heating element is activated when the temperature drops below a set value and stopped when it rises.

[0005] This method has limitations, such as significant power waste and low control efficiency, as the heating wires operate unnecessarily for extended periods even when actual freezing does not occur.

[0006] In addition, there is a problem where the control response is delayed, such as when heating begins only after sudden weather changes or on wet roads after snowfall, and conversely, when overheating is repeated even when the likelihood of freezing is low.

[0007] In particular, prolonged unnecessary heating can cause excessive increases in road surface temperatures, leading to structural damage such as cracking of the asphalt pavement, surface expansion, and spalling of bridge decks, and contributing to reduced lifespan of heating cables and increased maintenance costs.

[0008] Therefore, there is a need to develop intelligent road anti-icing control technology that can simultaneously prevent unnecessary power consumption and damage to road structures caused by overheating by analyzing weather and road surface conditions in real time to predict the risk of freezing and precisely controlling the output of heating wires according to the results. Prior art literature

[0009] Registered Patent 10-2427772 Registered Patent 10-2197761 The problem to be solved

[0010] The present invention aims to solve the problems of the conventional technology described above and simultaneously improves the issues of unnecessary power consumption and damage to road structures caused by overheating in electric heating cable systems for preventing freezing of roads and bridges.

[0011] In other words, by overcoming the limitations of the existing method of controlling heating wires solely through simple temperature sensing,

[0012] The main objective is to provide efficient control technology that supplies only the necessary heat at the required time by analyzing weather changes and road surface conditions in real time and predicting the risk of freezing in advance.

[0013] In addition, another task is to prevent unnecessary heating, minimize thermal damage to the road surface pavement layer, and improve the reliability and durability of the system by utilizing a power regulator (TPR) to finely control the power application to the heating wires and continuously adjusting the amount of current supplied.

[0014] In addition, the objective is to enable stable and efficient road de-icing operation even under long-term driving conditions by including an intelligent fail-safe control function that automatically switches to a safe driving mode to maintain the de-icing function even if sensor malfunctions or communication failures occur. means of solving the problem

[0015] To solve the above problem, the present invention proposes a prediction-based heating wire drive control method that collects and analyzes meteorological information such as temperature, humidity, wind speed, precipitation, and snowfall, as well as ambient temperature and road surface temperature data in real time, and predicts the possibility of freezing based on this to control the power output of the heating wire.

[0016] In the above control method, weather and road surface information is received as input, the dew point and freezing risk index are calculated, and changes in road surface temperature over a certain period of time are predicted through a prediction algorithm.

[0017] Based on the prediction results, the target output value of the heating wire is calculated and transmitted to the Thyristor Power Regulator (TPR) to continuously regulate the amount of current applied, thereby preemptively heating in sections at risk of freezing and minimizing the output when the likelihood of freezing is low.

[0018] In addition, the present invention improves the responsiveness and stability of temperature control by combining feedforward control and feedback control to respond to sudden weather changes or temporary data fluctuations.

[0019] In addition, if abnormal conditions such as sensor malfunctions or communication failures are detected, the system automatically switches to a temperature-based fail-safe step output mode to ensure the safety of the entire system.

[0020] In addition, where multiple heating cable sections exist, the system is configured to suppress overall power peaks and enable efficient energy operation by assigning priorities based on the freezing risk of each zone and distributing the load of the power feeder.

[0021] Thus, the present invention implements an intelligent road anti-icing heating wire control technology that can minimize power consumption and prevent overheating of the road pavement layer while maintaining the anti-icing effect. Effects of the invention

[0022] According to the present invention, by comprehensively analyzing weather information and road surface condition data in a heating cable system for preventing freezing of roads and bridges to predict the risk of freezing in advance, more precise and efficient control is possible compared to the existing simple temperature sensing method.

[0023] Accordingly, heat can be supplied preemptively before actual freezing occurs, and unnecessary heating can be suppressed in areas with a low probability of freezing, thereby significantly reducing power consumption while maintaining a stable anti-freezing effect.

[0024] In addition, by continuously controlling the applied power of the heating wire through a power regulator (TPR), rapid temperature fluctuations that occurred in the conventional simple ON / OFF method can be prevented, and the rate of rise in road surface temperature can be controlled gradually, thereby preventing damage caused by local overheating of the road pavement layer or bridge deck.

[0025] This reduces thermal stress on the heating wires, extending the lifespan of the equipment and providing the effect of reducing maintenance costs in the long term.

[0026] The prediction-based control method according to the present invention combines feedforward control, which can rapidly respond to weather changes and disturbances, with feedback control, which stably maintains a target value of road surface temperature, so that the road surface temperature can be stably maintained within a certain range even in situations of rapid temperature changes or snowfall and rainfall.

[0027] This can significantly reduce the probability of freezing and directly contribute to preventing traffic accidents and improving road safety.

[0028] In addition, the present invention automatically switches to a fail-safe mode even in abnormal situations such as sensor malfunctions or communication failures, allowing the entire system to operate stably without interruption.

[0029] Therefore, the reliability and environmental resistance of the anti-freezing system are significantly improved even in harsh environments such as severe cold.

[0030] In addition, when controlling multiple heating cable sections, the total power consumption can be distributed evenly through priority control based on the freezing risk index for each section and power feeder load distribution functions, thereby suppressing power peaks and responding to demand response (DR) control.

[0031] As a result, the present invention provides complex technical effects such as energy saving, prevention of overheating and protection of road structures, improvement of anti-icing effects, securing stability and reliability of the system, and improvement of maintenance efficiency, and is an invention with very high industrial utility value as an intelligent energy optimal control technology in the field of anti-icing of roads and bridges. Brief explanation of the drawing

[0032] FIG. 1 is a block diagram illustrating the overall configuration of a prediction-based road anti-icing heating wire drive control system according to the present invention. Figure 2 illustrates a flowchart of a prediction-based anti-freezing control algorithm according to the present invention. FIG. 3 is a schematic diagram illustrating the control operation structure of a power regulator (TPR) according to the present invention. Figure 4 is a graph showing the relationship between freezing risk prediction and power output optimization according to the present invention. FIG. 5 is a block diagram illustrating a section-by-section heating wire control and feeder power distribution scheduling structure according to the present invention. FIG. 6 is a diagram illustrating a fail-safe operation sequence in the event of a sensor malfunction or communication failure according to the present invention. Specific details for implementing the invention

[0033] FIG. 1 is a block diagram illustrating the overall configuration of a prediction-based road anti-icing heating wire drive control system according to the present invention.

[0034] The system is composed of a weather information unit (1), an outdoor air sensor unit (2), a control unit (3), a power regulator (4), a heating wire drive unit (5), a protection and monitoring circuit (6), a communication unit (7), and a control and display unit (8).

[0035] The weather information unit (1) measures temperature (T), humidity (RH), wind speed (V), precipitation (R), snow depth (S), etc., and the outside air sensor unit (2) detects the outside air temperature (Ta), road surface temperature (Ts), etc. and transmits them to the control unit (3).

[0036] The control unit (3) predicts the risk of freezing based on this data and determines the power output of the heating wire (5).

[0037] The power regulator (4) continuously controls the current applied to the heating wire (5) according to the target output indicator value (u*) calculated by the control unit (3).

[0038] The power regulator uses phase angle control and cycle control (burst fire) methods based on thyristor (SCR) or triac to smoothly regulate output power and prevent power surges and overheating.

[0039] The protection and monitoring circuit (6) monitors overcurrent, leakage current, insulation degradation, etc., and the communication unit (7) performs data exchange between the control unit (3) and the control and display unit (8) through a wired / wireless network.

[0040] The control and display unit (8) displays the freezing risk index, power consumption, and operating status by section in real time, allowing the operator to monitor and control the system.

[0041] With such a configuration, the present invention can prevent freezing of roads and bridges while preventing energy waste and road damage caused by overheating.

[0042] Figure 2 illustrates a flowchart of a prediction-based anti-freezing control algorithm according to the present invention.

[0043] This diagram sequentially illustrates the data collection stage, the dew point and freezing risk index calculation stage, the target output (u*) calculation stage by the predictive control algorithm, and the current control stage by the power regulator (TPR).

[0044] (1) Data collection step

[0045] The control unit (3) collects data such as temperature (T), humidity (RH), wind speed (V), precipitation (R), snow depth (S), ambient temperature (Ta), and road surface temperature (Ts) in real time from the weather information unit (1) and the ambient sensor unit (2).

[0046] (2) Step to calculate freezing risk

[0047] The dew point (Td) is calculated using the following Magnus equation based on the ambient temperature and humidity.

[0048]

[0049] The risk of condensation or freezing is determined through the relationship between the road surface temperature (Ts) and the dew point (Td), and

[0050] The freezing risk index (Ir) is calculated using the following formula.

[0051]

[0052] Here, T f θ is the melting point (0℃), W is the influence index of precipitation and snowfall, and κ is the environmental correction factor.

[0053] (3) Predictive control step

[0054] The control unit (3) predicts future changes in road surface temperature (Ts(t+k)) based on short-term forecasts and real-time data, and calculates the output u* of the heating wire so that no risk of freezing occurs.

[0055] The objective function of predictive control is defined as follows.

[0056] (Here, α, β, and γ are weights, respectively, t is the current time point, k is the prediction step (1 to H), and P is the power of the heating wire).

[0057] Constraints include 0 ≤ u ≤ 1, feeder capacity limit (∑u·P ≤ Pmax), temperature limit (Ts ≤ Tmax), etc.

[0058] Through this, the control unit calculates the optimal u*(t) and ensures that the road surface temperature does not drop below the freezing temperature during the prediction period (H).

[0059] Feedforward control preemptively compensates for disturbances (snowfall, sudden changes in wind speed), and feedback control ensures control stability by correcting the error between the actual measured temperature (Ts) and the target temperature.

[0060] (4) Power control stage

[0061] The calculated target output (u*) is transmitted to the power regulator (4) to continuously control the current.

[0062] In this process, the power regulator suppresses sudden output fluctuations through a ramp rate limiting function, thereby minimizing electrical and thermal stress on the heating wire.

[0063] Consequently, the control algorithm of the present invention enables preemptive response by activating the heating wire in advance when a risk of freezing is predicted, and automatically reduces the output when weather conditions stabilize, thereby realizing prediction-based energy optimal control.

[0064] FIG. 3 is a schematic diagram illustrating the control operation structure of a power regulator (TPR) according to the present invention.

[0065] The target output indicator value (u*) calculated by the control unit (3) is transmitted to the power regulator (4), and the power regulator continuously adjusts the phase angle or cycle ratio of the current applied to the heating wire (5).

[0066] The power regulator (4) includes a zero-crossing detection circuit to prevent power surges at the time of switching and maintains a constant current rise rate through a ramp rate limiting function.

[0067] In addition, an overcurrent and overheat protection circuit is built-in to ensure stable operation of the heating wire.

[0068] When multiple heating wire sections are operated in parallel, each power regulator (4) automatically adjusts its output within the feeder capacity (Pmax) according to the scheduling command of the control unit (3).

[0069] Through such a structure, the present invention can distribute the power load in a balanced manner while maintaining anti-freezing performance.

[0070] Figure 4 is a graph showing the relationship between freezing risk prediction and power output optimization according to the present invention.

[0071] This illustrates the relationship in which the heating wire output (u) is preemptively adjusted over time according to changes in ambient temperature (Ta), road surface temperature (Ts), dew point (Td), and freezing risk index (Ir).

[0072] As the outside temperature decreases and relative humidity increases, the freezing risk index (Ir) increases.

[0073] The control unit (3) preemptively increases the output of the heating wire according to this change to supply heat in advance before the road surface temperature drops below 0℃.

[0074] When weather conditions improve and the risk index decreases, the output is gradually reduced to prevent energy waste and overheating.

[0075] On the graph, u(t) has a curve shape that rises in proportion to Ir(t) and then gradually decreases, and this curve clearly shows the control characteristics of “prediction → output adjustment → correction” of the present invention.

[0076] FIG. 5 is a block diagram illustrating a section-by-section heating wire control and feeder power distribution scheduling structure according to the present invention.

[0077] A process for comparing freezing risk indices (Ir_i; i=1~n) for multiple heating wire sections (5-1~5-n; n=1~3), determining priority, load distribution per feeder, and section scheduling control is illustrated.

[0078] The scheduling controller (23) compares the Ir_i values ​​of each section in real time and prioritizes power allocation starting from the section with a high risk of freezing.

[0079] Power distribution is performed so as not to exceed the feeder capacity (Pmax), and partial output control is performed at 100%, 70%, 50%, etc., according to the thermal response characteristics of each section.

[0080] When the feeder load is concentrated, the control unit (3) automatically applies a load equalization algorithm to resolve power imbalance between feeders and readjusts the priority according to disturbances such as snowfall and changes in wind speed.

[0081] Through this scheduling structure, the present invention can prioritize securing prevention performance in sections with a high risk of freezing while suppressing overall power peaks.

[0082] FIG. 6 is a diagram illustrating a fail-safe operation sequence in the event of a sensor malfunction or communication failure according to the present invention.

[0083] The procedures for sensor anomaly detection, reliability assessment, safe output switching, and normal return are described step-by-step.

[0084] The abnormality diagnosis module (9) monitors the sensor's disconnection, sticking, communication error, etc., in real time, and if an abnormality occurs, the control unit (3) immediately switches to fail-safe mode.

[0085] In this mode, step output is applied based on the ambient temperature (Ta).

[0086] For example, it operates automatically at 60% power output at -5℃ or lower and 80% at -10℃ or lower.

[0087] When the abnormal condition is resolved, the control unit (3) stably checks the data for a certain verification time and then automatically returns to normal control mode, and during the return process, ramp rate control is applied to prevent current surge or thermal shock.

[0088] Therefore, even if sensor or communication failures occur, the anti-icing function continues, ensuring road safety and system reliability. Explanation of the symbols

[0089] 1 … … Weather Information Unit 2 … … Outdoor Air Sensor Unit 3 … … Control Unit 4 … … Thyristor Power Regulator (TPR) 5 … … Heating Wire Drive Unit (5-1~5-n; n=1~3) 6 … … Protection and Monitoring Circuit 7 … … Communication Unit 8 … … Human-Machine Interface / Supervisory Control and Data Acquisition (HMI / SCADA) 9 … … Fault Detection and Diagnosis Module (FDD) 10 … … Local Fail-Safe Control Logic 11 … … Weather Information Temperature (T) 12 … … Weather Information Humidity (RH) 13 … … Weather Information Wind Speed ​​(V) 14 … … Weather Information Precipitation (R) 15 … … Weather Information Snowfall (S) 16 … … Outdoor Air Temperature Sensor (Ta) 17 … … Road Surface Temperature Sensor (Ts) 18 … … Model Predictive Control (MPC) 19 … … Feedforward and feedback control unit 20 … … Target output indication value (u*) 21 … … Freezing risk index calculation unit 22 … … Dew point calculation unit 23 … … Scheduling controller (zone priority and feeder power distribution control) 24 … … Data storage and monitoring unit 25 … … Energy efficiency analysis unit 26 … … Overcurrent and overheating protection circuit 27 … … Zero crossing detection circuit 28 … … Ramp rate control circuit 29 … … Fail-safe step output setting unit 30 … … Control data server and record storage module

Claims

Claim 1 A step of collecting meteorological information including temperature (T), humidity (RH), wind speed (V), precipitation (R), and snow depth (S), and ambient information including ambient temperature (Ta) and road surface temperature (Ts); a step of calculating the dew point (Td) and freezing risk index (Ir) based on the meteorological information and ambient information; a step of predicting future road surface temperature changes based on weather change predictions; and a step of calculating the target output indicator value (u*) of the heating wire by applying a Model Predictive Control (MPC) algorithm, wherein the objective function of the predictive control is defined such that a weighted sum including the error between the target temperature (Ttarget) and the predicted road surface temperature (Ts), the heating wire output (u), and the output fluctuation (Δu) as terms is minimized during the prediction period (H), and the constraints of the predictive control are 0 ≤ u ≤ 1, a feeder power limit (Σu·P ≤ Pmax, where P is the power of the heating wire and Pmax is the feeder capacity), and A method for controlling the drive of a heating wire for preventing road freezing, characterized by including: a step of including a temperature limit (Ts ≤ Tmax, where Tmax is an allowable upper limit of the road surface temperature); and a step of continuously and variably controlling the power of the heating wire through a power regulator (TPR; Thyristor Power Regulator) according to the target output indicator value (u*). Claim 2 A method for controlling the drive of a heating wire for preventing road freezing, characterized in that, in claim 1, the dew point (Td) is calculated according to the following formula based on the ambient temperature (Ta) and humidity (RH). (where a = 17.62, b = 243.12℃) Claim 3 A method for controlling the drive of a heating wire for preventing road freezing, characterized in that, in claim 1, the freezing risk index (Ir) is calculated using the following formula. Here, T f θ is the melting point (0℃), W is the influence index based on precipitation and snowfall, and κ is the environmental correction factor. Claim 4 A method for controlling the drive of a heating wire for preventing road freezing, characterized in that, in claim 1, the objective function of the predictive control is defined by the following formula. Here, α, β, and γ are weights, t is the current time point, and k is the prediction step (1 to H), and the constraints include 0 ≤ u ≤ 1, feeder power limit (Σu·P ≤ Pmax), and temperature limit (Ts ≤ Tmax), where P is the power of the heating wire, Pmax is the feeder capacity, and Tmax is the allowable upper limit of the road surface temperature. Claim 5 A method for controlling the driving of a heating wire for preventing road freezing, wherein, in claim 1, the power regulator (TPR; 4) continuously adjusts the phase angle or cycle ratio of the current applied to the heating wire (5) using a phase angle control and cycle control (burst fire) method. Claim 6 A method for controlling a heating wire drive for road freezing prevention according to claim 1, wherein the control unit (3) performs feedforward control to preemptively compensate for disturbances including snowfall or sudden wind speed changes, and performs feedback control to correct the error between the actual measured temperature (Ts) and the target temperature to ensure the stability of the control. Claim 7 A method for controlling the operation of a heating wire for preventing road freezing according to claim 1, wherein the heating wire (5) is composed of a plurality of sections, and the control unit (3) compares the freezing risk index (Ir_i, where i is the section number) of each heating wire section in real time, prioritizes the allocation of power starting from the section with the highest risk, distributes power so as not to exceed the feeder capacity (Pmax), and includes a scheduling control step of operating at partial output according to the thermal response characteristics of each section. Claim 8 A method for controlling the operation of a heating cable for road freezing prevention according to claim 1, wherein the fault detection and diagnosis module (FDD, Fault Detection and Diagnosis; 9) detects sensor signal abnormalities, open circuits, and communication failures, and a fail-safe control step is automatically executed to maintain the anti-freezing function when an abnormality occurs. Claim 9 A method for controlling the drive of a heating wire for preventing road freezing according to claim 8, characterized in that, in the fail-safe control step, a step-by-step safety output is applied based on the ambient temperature (Ta), and the heating wire output is automatically operated at 60% when the temperature is -5℃ or lower and at 80% when the temperature is -10℃ or lower, thereby maintaining the anti-freezing function. Claim 10 A weather information unit (1) that measures weather information including temperature (T), humidity (RH), wind speed (V), precipitation (R), and snow depth (S); an ambient air sensor unit (2) that detects ambient air information including ambient temperature (Ta) and road surface temperature (Ts); a dew point (Td) and freezing risk index (Ir) are calculated based on the weather information and ambient air information, future road surface temperature changes are predicted based on weather change predictions, and a target output indicator value (u*) of a heating wire is calculated by applying a Model Predictive Control (MPC) algorithm, wherein the objective function of the prediction control is defined such that a weighted sum including the error between the target temperature (Ttarget) and the predicted road surface temperature (Ts), the heating wire output (u), and the output fluctuation (Δu) as terms is minimized during the prediction period (H), and the constraints of the prediction control are 0 ≤ u ≤ 1, feeder power limit (Σu·P ≤ Pmax, where P is the power of the heating wire and Pmax is A prediction-based road freezing prevention heating cable drive control system characterized by comprising: a control unit (3) including a feeder capacity and a temperature limit (Ts ≤ Tmax, where Tmax is the allowable upper limit of the road surface temperature); a power regulator (TPR, Thyristor Power Regulator; 4) that continuously variably controls the current applied to the heating cable (5) according to the target output indicator value (u*); a heating cable drive unit (5) that generates heat with power applied by the power regulator (4); a communication unit (7) that performs data exchange between the control unit (3) and the control and display unit (8) through a wired or wireless network; and a control and display unit (HMI / SCADA, Human-Machine Interface / Supervisory Control and Data Acquisition; 8) configured to display the freezing risk index, power consumption, and operating status by section in real time, and to allow an operator to remotely monitor and control the system through the communication unit (7).

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