Control method and system of building block type flexible dc ice melting device

Abstract

The control method and system of the modular flexible DC de-icing device, in each control cycle, performs thermal inertia compensation correction on the target de-icing power based on the deviation between the de-icing process index and the reference de-icing process index, and the deviation between the current ice thickness and the target ice thickness value. The corrected target de-icing power is then limited and ramped up to obtain the power command. All units are sorted in descending order according to the health factor. A set of healthy units that execute the power command is selected from the sorted data, and the power command is allocated to each healthy unit according to the health factor. The deviation between the actual output current and the target output current of each healthy unit is used as the control error. The duty cycle of each healthy unit is adjusted through a proportional-integral controller, and the trigger phase of each healthy unit is adjusted according to the bus ripple level and the power deviation of the healthy unit to perform adaptive phase-shifting triggering on each healthy unit. This achieves rapid, smooth, uniform, and continuous de-icing of long-distance transmission lines.

Description

Technical Field

[0001] This invention belongs to the field of power transmission and anti-icing technology, and particularly relates to a control method and system for a modular flexible DC de-icing device. Background Technology

[0002] In cold regions, power transmission lines are prone to icing in winter, leading to reduced line load capacity, increased tower stress, and potentially causing conductor breakage or tower collapse, seriously threatening power grid safety. Traditional de-icing methods mainly include mechanical knocking, hot air heating, and AC transmission heating, but these methods suffer from low efficiency, imprecise control, energy waste, and significant line losses.

[0003] With the development of DC transmission technology, DC heating for ice melting has become a research hotspot. DC ice melting involves applying DC current to the line, causing the conductors to generate heat and melt the covering ice layer. This method achieves uniform heating and is relatively simple to operate. However, existing DC ice melting systems typically suffer from problems such as single-module design, poor flexibility, and low fault tolerance, making it impossible to maintain continuous heating of the line when some modules fail. Furthermore, due to the long conductor length, uneven ice layer thickness, and large fluctuations in bus current, localized overheating or uneven heating of the conductors can easily occur, reducing ice melting efficiency.

[0004] Furthermore, existing systems mostly employ fixed current or power output in their control strategies, lacking the ability to dynamically adjust to environmental factors and line icing conditions, making it difficult to achieve precise de-icing. Poor system scalability also limits the application of high-capacity lines. Summary of the Invention

[0005] To address the problems of existing DC de-icing devices, such as target power calculation relying on static empirical values, module allocation only considering instantaneous operating states, a single output reconstruction method after a fault, and difficulty in simultaneously ensuring uniformity, continuity, and device lifespan during the de-icing process under long-distance line icing conditions, this invention provides a control method and system for a modular flexible DC de-icing device. Based on a modular DC power unit topology, this method constructs a power generation mechanism combining de-icing process sensing and line thermal state correction, a multi-dimensional health allocation mechanism considering thermal stress and accumulated load, and an adaptive phase reconfiguration mechanism for bus ripple suppression, thereby achieving rapid, smooth, uniform, and continuous de-icing of long-distance transmission lines.

[0006] The present invention adopts the following technical solution: This invention proposes a control method for a modular flexible DC ice-melting device, comprising: Obtain information on the icing status of the line and the operating information of each DC power unit; Throughout the entire de-icing process, within each control cycle, based on the line icing status information, the de-icing progress index and target de-icing power are calculated. Based on the deviation between the de-icing progress index and the de-icing progress reference index, and the deviation between the current icing thickness and the target icing thickness, the target de-icing power is corrected by thermal inertia compensation. The corrected target de-icing power is then limited and ramped up to obtain the power command. Based on the operating information of each DC power unit, a health factor for each DC power unit is established, and all units are sorted in descending order of health factor. In the sorting, a set of healthy units that can execute power commands is selected, and power commands are assigned to each healthy unit according to the health factor. Based on the power command and output DC voltage allocated to each health unit, the target output current of each health unit is determined; the deviation between the actual output current and the target output current of each health unit is used as the control error, and the duty cycle of each health unit is adjusted through the proportional-integral controller. The trigger phase of each health unit is also adjusted according to the bus ripple level and the power deviation of the health unit to perform adaptive phase-shift triggering for each health unit.

[0007] When the ice-melting device submodule fails, a fault reconstruction topology is established based on the modular structure of the ice-melting device. Based on the fault reconstruction topology, the multidimensional health factor is updated and the power command is allocated to each healthy unit according to the updated health factor. The duty cycle and trigger phase of each healthy unit are adaptively adjusted to perform adaptive phase reversal triggering on each healthy unit under the fault reconstruction topology.

[0008] The weighted sum of the rate of change of ice thickness and the rate of change of conductor temperature is used as an indicator of the ice melting process, as shown in the following formula:

[0009] In the formula, To control the cycle Indicators of the ice melting process; To control the cycle The thickness of the ice cover; To control the cycle The temperature of the conductor; To control cycle duration; and These are the weighting coefficients.

[0010] Target ice melting power As shown in the following formula:

[0011] In the formula, , , , , Control cycle The target de-icing power, conductor ice thickness, ambient temperature, wind speed, and conductor temperature. To consider the overall thermal characteristic coefficient, For the length of the transmission line, The target temperature for the conductor. , This is a correction factor.

[0012] The corrected target melting power is shown in the following formula:

[0013] In the formula, To control the cycle The revised target ice melting power; This represents the target value for ice thickness. As a reference indicator for the ice melting process; and This is a correction factor.

[0014] The power command obtained by applying the corrected target ice-melting power limit and ramp correction is shown in the following formula:

[0015] In the formula, For the current control cycle Power command, For the previous control cycle - Power command, This represents the upper limit of power ramp-up.

[0016] Based on the operating information of each DC power unit, a multidimensional health factor is established for each DC power unit. The multidimensional health factor simultaneously considers the unit's operating status, current margin, voltage margin, device temperature rise, and cumulative operating load, and all units are sorted in descending order according to the multidimensional health factor. If sorted first The sum of the output power of all units is greater than the power command and is ranked first. If the total output power of -1 unit is less than the power command, then it is ranked first. Each unit constitutes a set of health units; Based on the multidimensional health factor of each health unit in the health unit set, and in combination with the reserved capacity constraint, the power command is allocated to each health unit.

[0017] The multidimensional health factor is shown in the following formula:

[0018] In the formula, To control the cycle No. Health factor of each DC power unit To control the cycle No. The state coefficient of each DC power unit is 1 when the unit is operating at its rated power, a value between 0 and 1 when the unit is operating at derating, and 0 when the unit fails and exits the operation. and The first The maximum allowable output current and maximum output voltage of each DC power unit; , Control cycle No. The output DC voltage and output DC current of each DC power unit; , , These are the weighting coefficients, and + + =1.

[0019] The power command is assigned to each health unit, as shown in the following formula:

[0020] st

[0021] In the formula, To control the cycle No. Power commands allocated to each healthy unit. To control the cycle Health unit collection, For the current control cycle Power command, To reserve capacity factor, and 0 < <1, For the first The maximum permissible output power of each healthy unit.

[0022] The target output current is determined based on the power command and output DC voltage allocated to each health unit; The difference between the output current of each healthy unit and the target output current is used as the control error, and the duty cycle of each healthy unit is adjusted by a proportional-integral controller. The trigger phase of each healthy unit is determined by the basic phase reversal angle and the phase correction amount; among which, the adaptive correction angle is adjusted according to the bus ripple level and the power deviation of the healthy unit.

[0023] The trigger phase of the i-th healthy unit is shown in the following formula:

[0024] In the formula, To control the cycle No. The trigger phase of each healthy unit, To control the cycle The number of internal health units, To control the cycle No. The basic phase shift angle of each healthy unit To control the cycle No. The phase correction of each healthy unit is adaptively adjusted based on the bus current ripple level and unit power deviation.

[0025] In another aspect, the present invention also proposes a control system for a modular flexible DC ice-melting device, comprising: The data acquisition module is used to obtain information on the icing status of the line and the operating information of each DC power unit; The power command generation module is used to calculate the ice melting progress index and the target ice melting power based on the line icing status information in each control cycle during the entire ice melting process. It performs thermal inertia compensation correction on the target ice melting power based on the deviation between the ice melting progress index and the ice melting progress reference index, and the deviation between the current icing thickness and the target icing thickness. It then limits and corrects the target ice melting power after correction to obtain the power command. The power command allocation unit is used to establish the health factor of each DC power unit based on the operating information of each DC power unit, sort all units in descending order of health factor, select the set of healthy units that can execute power commands in the sorting, and allocate power commands to each healthy unit according to the health factor. The trigger command modulation module is used to determine the target output current of each health unit based on the power command and output DC voltage allocated to each health unit; using the deviation between the actual output current and the target output current of each health unit as the control error, the duty cycle of each health unit is adjusted through the proportional-integral controller, and the trigger phase of each health unit is adjusted according to the bus ripple level and the power deviation of the health unit, so as to perform adaptive phase-shift triggering for each health unit.

[0026] The fault reconstruction module is used to establish a fault reconstruction topology based on the modular structure of the ice melting device when the ice melting device submodule fails. Based on the fault reconstruction topology, the power command allocation unit is called to update the multi-dimensional health factor and allocate the power command to each healthy unit according to the updated health factor. The trigger command modulation module is called to adaptively adjust the duty cycle and trigger phase of each healthy unit to perform adaptive phase-shifting triggering on each healthy unit under the fault reconstruction topology.

[0027] The present invention is also a terminal, including a processor and a storage medium; the storage medium is used to store instructions; the processor is used to perform operations according to the instructions to execute the steps of the above method.

[0028] The present invention is also a computer-readable storage medium having a computer program stored thereon, which, when executed by a processor, implements the steps of the above-described method.

[0029] Compared with the prior art, the present invention has at least the following beneficial effects: The present invention not only incorporates the icing state of the line, environmental factors and conductor thermal state into the de-icing power calculation process, but also further utilizes the change in icing thickness and conductor temperature rise rate within a continuous control cycle to construct de-icing process indicators, and combines thermal inertia compensation, amplitude limiting and full-range ramp correction to generate power commands, so that the target de-icing power has both operating condition self-adaptability and good dynamic smoothness.

[0030] Meanwhile, in the process of module power allocation, this invention not only considers the unit operating status, current margin and voltage margin, but also introduces device temperature rise and cumulative operating load to construct a multi-dimensional health factor that balances short-term load capacity and long-term lifespan. It also improves fault ride-through capability by reserving capacity constraints, thus avoiding long-term overload of local modules caused by traditional average allocation methods or simple instantaneous weighting methods.

[0031] Furthermore, this invention does not rely solely on the number of healthy modules for fixed phase misalignment control. Instead, it adaptively corrects the trigger phase by combining the bus ripple level and unit power deviation, maintaining low bus ripple even under conditions of module exit, recovery, or load fluctuations. Therefore, this invention offers significant advantages in terms of de-icing uniformity, fault tolerance, control precision, lifespan consistency, and adaptability to large-capacity expansion, making it suitable for flexible DC de-icing applications in high-voltage, ultra-high-voltage, and long-distance transmission lines. Attached Figure Description

[0032] Figure 1 A flowchart illustrating a control method for a modular flexible DC ice-melting device provided by the present invention. Detailed Implementation

[0033] To make the objectives, technical solutions, and advantages of this invention clearer, the technical solutions of this invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments of this invention. The embodiments described in this application are merely some embodiments of this invention, and not all embodiments. Based on the spirit of this invention, all other embodiments obtained by those skilled in the art without creative effort are within the protection scope of this invention.

[0034] The modular flexible DC de-icing device employs multiple DC power units connected in series to form a DC bus. Each DC power unit consists of a voltage source converter and a DC chopper circuit, and AC isolation is achieved through a multi-winding transformer, ensuring independent operation of the modules and system fault tolerance. This modular design guarantees that each module, i.e., a single DC power unit, can work independently, while ensuring that the remaining modules can maintain stable operation even if one module fails.

[0035] This invention proposes a control method for a modular flexible DC ice-melting device, such as... Figure 1 As shown, it includes the following steps: Step 1: Obtain information on the icing status of the line and the operating information of each DC power unit.

[0036] Specifically, the line icing status information includes, but is not limited to: control cycle. ice thickness of the conductor Ambient temperature Wind speed and wire temperature The operating information of each DC power unit includes, but is not limited to: control cycle. The system collects data in real time. The output DC voltage of each DC power unit Output DC current Output power and the total output voltage of the DC de-icing device. .

[0037] Control cycle No. Output power of each DC power unit for: (1) Multiple DC power units are connected in series to form a DC bus, and the total output voltage of the DC ice melting device is... for: (2) In the formula, This refers to the number of DC power units that are in operation.

[0038] Step 2: During the entire de-icing process, in each control cycle, the de-icing progress index and target de-icing power are calculated based on the line icing status information. The target de-icing power is then corrected by thermal inertia compensation based on the de-icing progress index and icing thickness. The corrected target de-icing power is then limited and the ramp correction is applied to obtain the power command.

[0039] Specifically, step 2 includes: Step 2.1: Based on the line icing status information and the icing change trend within the continuous control cycle, the weighted sum of the icing thickness change rate and the conductor temperature change rate is used as an indicator of the de-icing process, which can be expressed as: (3) In the formula, To control the cycle Indicators of the ice melting process; To control the cycle The thickness of the ice cover; To control the cycle The temperature of the conductor; To control cycle duration; and These are the weighting coefficients.

[0040] Before calculating the target de-icing power, a de-icing progress index is constructed based on the change in ice thickness and the conductor temperature rise rate within adjacent control cycles. This index characterizes the matching relationship between the ice melting rate and the conductor thermal response under the current operating conditions. If the de-icing progress index is lower than the lower limit of the preset range, it indicates that the current output power is insufficient to meet the de-icing rate requirements. If the de-icing progress index is higher than the upper limit of the preset range, it indicates the risk of local overheating or redundant energy input, requiring dynamic correction of the target de-icing power.

[0041] In practical implementation, the ice-melting process index can be normalized relative to the ice-melting process reference index, and the preset range of the resulting relative ice-melting process index can be set to [0.8, 1.2]. When the relative ice-melting process index is lower than 0.8, it indicates that the current output power is insufficient to meet the ice-melting rate requirements, and the target ice-melting power needs to be appropriately increased; when the relative ice-melting process index is higher than 1.2, it indicates that there is a risk of local overheating or redundant energy input, and the target ice-melting power needs to be appropriately reduced; when the relative ice-melting process index is within the range of [0.8, 1.2], the current target ice-melting power is maintained unchanged or only smooth fine-tuning is performed.

[0042] Step 2.2: Calculate the target de-icing power based on the line icing status information.

[0043] Unlike fixed power output methods, this invention incorporates ice thickness, ambient temperature, wind speed, and real-time conductor temperature into the ice-melting power calculation process, employing a continuous analytical function to calculate the target ice-melting power. It can be represented as: (4) In the formula, To control the cycle The target ice melting power, To consider the overall thermal characteristic coefficient, For the length of the transmission line, The target temperature for the conductor. , As a correction factor, a value of 0.5 is preferred in the embodiment.

[0044] Furthermore, this invention uses the continuous analytical function shown in equation (4) to replace the traditional hierarchical discrete threshold judgment, so that the target de-icing power changes continuously with the line icing status information; and, in advance, a mapping table of comprehensive thermal characteristic coefficients, correction coefficients and conductor icing thickness, ambient temperature, wind speed and conductor temperature is established through finite element simulation or de-icing test. During online operation, the comprehensive thermal characteristic coefficients and correction coefficients under the current working condition are obtained through multidimensional interpolation, avoiding the problem of fixed coefficient fitting formulas being unable to adapt to the continuous changes of working conditions and having limited accuracy, and enabling online calculation; based on the continuous analytical function and coefficients changing continuously and adaptively with the working conditions, the step source of power command is fundamentally eliminated.

[0045] Step 2.3: Perform thermal inertia compensation correction on the target ice melting power based on the ice melting process indicators and ice thickness.

[0046] After calculating the target de-icing power, this invention further combines de-icing process indicators to perform thermal inertia compensation correction on the target de-icing power, in order to compensate for the lag in conductor temperature rise and the dynamic deviation in the ice melting process, and avoid the problem of slow adjustment caused by calculating the target power based only on the ice state at a single moment.

[0047] The corrected target melting power can be expressed as: (5) In the formula, To control the cycle The revised target ice melting power; This represents the target value for ice thickness. As a reference indicator for the ice melting process; and This is a correction factor.

[0048] The target value for icing thickness is used to characterize the remaining icing thickness when the de-icing process is nearing completion. Its value can be determined based on the line's safe operation requirements, the conditions for the conductor to regain normal current-carrying capacity, and the accuracy of icing detection. In one embodiment, The acceptable range is 0 mm to 2 mm, with a preferred range of 0.5 mm to 1 mm. In this embodiment, the target value for icing thickness is determined based on the conductor's safe operation requirements and the accuracy of icing detection. Set to 1 mm. When the monitored icing thickness... When the ice thickness is ≤1 mm, the system determines that the ice melting process is basically complete and enters the exit transition phase.

[0049] This serves as a reference index for the ice-melting process, characterizing the reference level at which the target ice-melting rate matches the conductor's thermal response. Its value can be obtained by calibration based on ice-melting test data, thermal balance simulation results, or historical operating data under typical icing conditions. In this embodiment, the average ice-melting process index during the stable ice-melting stage under typical conditions can be taken as... Typical operating parameters include: 10 mm ice thickness, -5°C ambient temperature, and 3 m / s wind speed. A standard de-icing test was conducted under these conditions, recording the rate of change of ice thickness and the conductor temperature rise rate during the stage with the highest de-icing efficiency and no local overheating (defined as the period from 5 minutes after the start of de-icing until the ice thickness drops to 3 mm). The average de-icing progress index for this stage was calculated to be 0.62. Therefore, the following parameters were set: = 0.62.

[0050] In this embodiment, based on the conductor specifications and system response characteristics, the following settings are made: = 0.5, = 0.3. Wherein Greater than This reflects the dominant role of icing thickness deviation in power correction. Smaller noise levels are used to suppress the disturbance of power command caused by temperature rise measurement noise.

[0051] Thermal inertia compensation correction makes the generation of power commands no longer dependent on the static icing state information at the current moment, but introduces information from two dimensions: the changing trend and historical deviation, thus realizing predictive compensation for the thermal inertia of the conductor and the dynamic characteristics of ice melting.

[0052] Step 2.4: Adjust the target melting power limit and ramp correction to obtain a smooth and continuous power command.

[0053] Typically, modular flexible DC de-icing devices are implemented based on modular multilevel converter (MMC) technology. During operation, the output power of these devices may exhibit abrupt changes or fluctuations. To further limit power variations, achieve smooth transitions, and avoid current surges caused by sudden power changes, a ramp-up correction is applied to the target de-icing power to obtain the actual power command, as shown in the following equation: (6) In the formula, For the current control cycle Power command, For the previous control cycle - Power command, This is the upper limit of power ramp-up. The duration of a control cycle.

[0054] Typically, ramp correction is only used for transient startup or shutdown and is executed only once. However, this invention combines ramp correction with thermal inertia compensation throughout the entire de-icing process, executing continuously in each control cycle. This allows the power command to reflect the continuous changes in the icing state and the de-icing process while suppressing rapid power oscillations caused by environmental disturbances, thus achieving smooth tracking throughout the entire process.

[0055] This invention does not employ a fixed power or simple equal-distribution control method. Instead, it combines parameters such as line icing thickness, ambient temperature, wind speed, and real-time conductor temperature to dynamically calculate and correct the target de-icing power, making the output power more consistent with the actual de-icing needs of the line, thereby improving control accuracy and reducing the risk of local overheating.

[0056] Step 3: Based on the operating information of each DC power unit, establish the health factor of each DC power unit, and sort all units in descending order of health factor; in the sorting, select the set of healthy units that execute power commands, and allocate power commands to each healthy unit according to the health factor.

[0057] Specifically, based on the operating information of each DC power unit, a multi-dimensional health factor is established that takes into account both instantaneous load capacity and long-term thermal stress. The multi-dimensional health factor comprehensively reflects the unit's operating status, current margin, voltage margin, device temperature rise, and cumulative operating load. All units are sorted in descending order according to the multi-dimensional health factor. In the sorting, a set of healthy units that execute power commands is selected, and under the reserved capacity constraint, the power commands are allocated to each healthy unit according to the multi-dimensional health factor.

[0058] Specifically, step 3 includes: Step 3.1: Based on the operating information of each DC power unit, establish a multidimensional health factor for each DC power unit. The multidimensional health factor simultaneously considers the unit's operating status, current margin, voltage margin, device temperature rise, and cumulative operating load, and sorts all units in descending order according to the multidimensional health factor.

[0059] To avoid the problems of long-term high-load operation and thermal stress concentration in some units caused by traditional average distribution methods or distribution based solely on instantaneous voltage and current margins, this invention introduces a multi-dimensional health factor that balances short-term load-bearing capacity and lifespan balance requirements. Its expression is: (7) In the formula, To control the cycle No. Health factor of each DC power unit To control the cycle No. The state coefficient of each DC power unit is 1 when the unit is operating at its rated power, a value between 0 and 1 when the unit is operating at derating, and 0 when the unit fails and exits the operation. and The first The maximum allowable output current and maximum output voltage of each DC power unit; , , These are the weighting coefficients, and + + =1.

[0060] In this embodiment, the state coefficient value is set according to the derating ratio of the unit. For example, if the actual output power is 75% of the rated power, the state coefficient value is 0.75.

[0061] Step 3.2, if the sorting order is first The sum of the output power of all units is greater than the power command and is ranked first. If the total output power of -1 unit is less than the power command, then it is ranked first. Each unit constitutes a set of healthy units.

[0062] This invention automatically determines the set of healthy units participating in the output by sorting by health status and filtering by the minimum set driven by power demand. Units with high health status take priority in bearing power, while units with low health status automatically take turns resting. Under the premise of satisfying power commands, the number of participating units is minimized, which improves system efficiency and extends the overall lifespan.

[0063] Step 3.3: Based on the multidimensional health factor of each health unit in the health unit set and in combination with the reserved capacity constraint, the power command is allocated to each health unit.

[0064] To improve fault ride-through capability, healthy units do not operate at their maximum output under normal de-icing conditions, but instead reserve some release capacity. When a unit is dated or shut down, the remaining healthy units can prioritize releasing the reserved capacity to maintain bus output continuity, thereby reducing the power drop during a fault. The power allocated to each healthy unit satisfies: (8) In the formula, To control the cycle No. The power allocated to each healthy unit, To reserve capacity factor, and 0 < <1; For the first The maximum permissible output power of each healthy unit.

[0065] The power command is assigned to each health unit, as shown in the following formula: (9) st (10) In the formula, To control the cycle No. Power commands allocated to each healthy unit. To control the cycle A collection of health units.

[0066] The power command allocated to each healthy unit must meet the maximum current constraint and total voltage constraint of each unit. If it does not meet the constraint, the allocated power of the unit exceeding the constraint shall be reduced proportionally and the reduced part shall be redistributed to other units. In this way, the allocation result can be dynamically adjusted according to the real-time status of each unit, thereby improving the reliability of system operation.

[0067] This invention introduces a dynamic power allocation strategy based on multi-dimensional health status, which can weight the de-icing power according to the operating status, current margin, voltage margin, device temperature rise and cumulative operating load of each unit. This avoids the problem of long-term overload of local modules under the traditional average allocation method or simple instantaneous weighting method, and improves the fault ride-through capability by reserving capacity constraints, thereby further improving the system's operational reliability and lifespan balance.

[0068] Step 4: Determine the target output current of each health unit based on the power command and output DC voltage allocated to each health unit; use the deviation between the actual output current and the target output current of each health unit as the control error, adjust the duty cycle of each health unit through the proportional-integral controller, and adjust the trigger phase of each health unit according to the bus ripple level and the power deviation of the health unit to perform adaptive phase-shift triggering on each health unit, so that the actual output current tracks the target output current and reduces the bus current ripple.

[0069] Specifically, step 4 includes: Step 4.1, according to the power command allocated to each health unit. and output DC voltage The target output current is determined as shown in the following formula: (11) In the formula, To control the cycle No. The target output current of each healthy unit.

[0070] Step 4.2: Using the difference between the output current of each healthy unit and the target output current as the control error, adjust the duty cycle of each healthy unit through a proportional-integral controller. (12) In the formula, To control the cycle No. Control error of each health unit; (13) In the formula, For the first The health unit in the first Duty cycle at each sampling time, For the first The health unit in the first Control error at each sampling time, , These are the proportional coefficient and the integral coefficient, respectively.

[0071] Step 4.3, the trigger phase of the i-th healthy unit is determined by the basic phase reversal angle and the phase correction amount, which can be expressed as: (14) In the formula, To control the cycle No. The trigger phase of each healthy unit; To control the cycle The number of internal health units, To control the cycle No. The basic phase shift angle of each healthy unit; To control the cycle No. The phase correction of each healthy unit is adaptively adjusted based on the bus current ripple level and unit power deviation.

[0072] When the bus current ripple exceeds a preset threshold, the controller increases the equivalent phase dispersion between adjacent healthy units. When the module power distribution is unbalanced, phase compensation correction is applied to the healthy units that bear a larger output power to reduce the peak value of the superimposed bus current. Therefore, this invention does not simply perform fixed equal-interval phase reversal based on the number of healthy units, but rather performs dynamic phase reconstruction based on the bus ripple suppression requirements and unit power deviation, thereby maintaining a low bus ripple even when modules exit, resume, or experience sudden load changes.

[0073] Through phase-shift triggering, the actual output current of each healthy unit is superimposed on the bus, controlling the cycle. The total bus current can be expressed as: (14) The present invention employs a phase-staggered superposition method, which can significantly improve the equivalent switching frequency, make the DC bus current smoother, reduce current ripple, and thus ensure that the conductor generates uniform heat and achieves efficient de-icing.

[0074] This invention employs a combination of phase-shifting chopping and closed-loop current sharing control to increase the equivalent switching frequency without increasing the unit switching frequency, thereby reducing bus current ripple, making the transmission conductors heat up more evenly, and improving de-icing efficiency. When a unit fails and exits, the trigger phase can be reconfigured according to the number of remaining units to achieve phase-shifting reconfiguration control after the fault, ensuring the continuous operation of the de-icing process.

[0075] Step 5: When a submodule of the ice-melting device fails, a fault reconstruction topology is established based on the modular structure of the ice-melting device. Based on the fault reconstruction topology, the multidimensional health factor is updated and the power command is allocated to each healthy unit according to the updated health factor. The duty cycle and trigger phase of each healthy unit are adaptively adjusted to perform adaptive phase reversal triggering on each healthy unit under the fault reconstruction topology, thereby realizing the hierarchical fault-tolerant control and multi-condition operation control of the flexible DC ice-melting device.

[0076] Because the ice-melting device of this invention adopts a modular design approach, cascading multiple DC power units to form an integrated DC bus, it has good scalability and fault tolerance. Even if some units malfunction, the system can maintain continuous operation through derating, releasing reserved capacity, and bypass mechanisms. When an overcurrent, overvoltage, device overtemperature, or internal control abnormality is detected in a DC power unit, the controller first performs fault classification processing on the unit based on the duration and amplitude of the abnormality. For units with minor abnormalities, derating is first implemented and the reserved capacity of the remaining healthy units is released. For units with persistent abnormalities or severe faults, the corresponding bypass branch is activated to disconnect the faulty module, and the power allocation result and adaptive phase reversal trigger angle are reconfigured based on the number of remaining healthy units to maintain continuous system operation. The effective bus voltage after fault reconstruction is: (15) Therefore, this invention realizes a hierarchical fault-tolerant control process from anomaly identification, derating operation, reserved capacity release to bypass removal. Compared with the method of directly removing faulty modules, it can reduce the output fluctuation at the moment of failure and improve the continuous de-icing capability.

[0077] The system can switch between de-icing mode, DC transmission mode, and power compensation mode. In de-icing mode, the system determines the current operating status based on the rate of change of ice thickness, conductor temperature rise slope, and bus ripple level, and uses dual-threshold hysteresis logic to switch between the rapid heating stage, stable de-icing stage, and termination exit stage, while dynamically adjusting the output power. In DC transmission mode, the system operates in conventional DC transmission mode. In power compensation mode, the output is adjusted according to grid power fluctuations to improve power quality and operational stability.

[0078] The system also features overcurrent, overvoltage, and overtemperature protection, as well as multi-condition switching capabilities. It can flexibly switch between de-icing mode, DC transmission mode, and power compensation mode according to operational needs. Furthermore, a dual-threshold hysteresis mechanism avoids frequent back-and-forth cycles caused by sensor fluctuations or short-term environmental disturbances, thereby improving the stability of mode switching and the continuity of control. In summary, this invention enables rapid, uniform, and efficient de-icing of long-distance transmission lines, while also considering system scalability, fault tolerance, control precision, lifespan balance, and operational stability.

[0079] In a typical application, the line length is 100km, the ice thickness is 20mm, the single module capacity is 2MW, the number of units is 10, and the DC bus voltage is 200kV. After the system enters the de-icing mode, it calculates the de-icing power in real time and distributes it to each module. Uniform conductor heating is achieved through phase-shifting chopping and smoothing current. At the same time, the controller monitors the module voltage and current and implements protection measures. After de-icing is completed, the system can switch to DC transmission or power compensation mode to ensure grid stability.

[0080] For a detailed comparison of the multiple operating modes, please refer to Table 1: Table 1 Comparison of Multi-condition Operating Modes

[0081] This invention achieves rapid, smooth, uniform, and continuous de-icing of long-distance transmission lines through a combination of modular design, power calculation integrating de-icing process sensing and thermal state correction, dynamic power allocation based on multi-dimensional health factors, adaptive phase-shifting chopper current sharing control, and hierarchical fault-tolerant reconfiguration control. The system not only possesses excellent scalability and fault tolerance but also dynamically adjusts the output power according to actual icing conditions. Furthermore, it enhances operational stability through staged control and hysteresis switching, making it suitable for de-icing applications on high-voltage and ultra-high-voltage transmission lines and possessing significant engineering application value.

[0082] In another aspect, the present invention also proposes a control system for a modular flexible DC ice-melting device, comprising: The data acquisition module is used to obtain information on the icing status of the line and the operating information of each DC power unit; The power command generation module is used to calculate the ice melting progress index and the target ice melting power based on the line icing status information in each control cycle during the entire ice melting process. It performs thermal inertia compensation correction on the target ice melting power based on the deviation between the ice melting progress index and the ice melting progress reference index, and the deviation between the current icing thickness and the target icing thickness. It then limits and corrects the target ice melting power after correction to obtain the power command. The power command allocation unit is used to establish the health factor of each DC power unit based on the operating information of each DC power unit, sort all units in descending order of health factor, select the set of healthy units that can execute power commands in the sorting, and allocate power commands to each healthy unit according to the health factor. The trigger command modulation module is used to determine the target output current of each health unit based on the power command and output DC voltage allocated to each health unit; using the deviation between the actual output current and the target output current of each health unit as the control error, the duty cycle of each health unit is adjusted through the proportional-integral controller, and the trigger phase of each health unit is adjusted according to the bus ripple level and the power deviation of the health unit, so as to perform adaptive phase-shift triggering for each health unit.

[0083] The fault reconstruction module is used to establish a fault reconstruction topology based on the modular structure of the ice melting device when the ice melting device submodule fails. Based on the fault reconstruction topology, the power command allocation unit is called to update the multi-dimensional health factor and allocate the power command to each healthy unit according to the updated health factor. The trigger command modulation module is called to adaptively adjust the duty cycle and trigger phase of each healthy unit to perform adaptive phase-shifting triggering on each healthy unit under the fault reconstruction topology.

[0084] This disclosure can be a system, method, and / or computer program product. A computer program product may include a computer-readable storage medium having computer-readable program instructions loaded thereon for causing a processor to implement various aspects of this disclosure.

[0085] Computer-readable storage media can be tangible devices capable of holding and storing instructions for use by an instruction execution device. Computer-readable storage media can be, for example—but not limited to—electrical storage devices, magnetic storage devices, optical storage devices, electromagnetic storage devices, semiconductor storage devices, or any suitable combination of the foregoing. More specific examples (a non-exhaustive list) of computer-readable storage media include: portable computer disks, hard disks, random access memory (RAM), read-only memory (ROM), erasable programmable read-only memory (EPROM or flash memory), static random access memory (SRAM), portable compact disc read-only memory (CD-ROM), digital multifunction disc (DVD), memory sticks, floppy disks, mechanical encoding devices, such as punch cards or recessed protrusions storing instructions thereon, and any suitable combination of the foregoing. The computer-readable storage media used herein are not to be construed as transient signals themselves, such as radio waves or other freely propagating electromagnetic waves, electromagnetic waves propagating through waveguides or other transmission media (e.g., light pulses through fiber optic cables), or electrical signals transmitted through wires.

[0086] The computer-readable program instructions described herein can be downloaded from computer-readable storage media to various computing / processing devices, or downloaded via a network, such as the Internet, local area network, wide area network, and / or wireless network, to an external computer or external storage device. The network may include copper transmission cables, fiber optic transmission, wireless transmission, routers, firewalls, switches, gateway computers, and / or edge servers. A network adapter card or network interface in each computing / processing device receives the computer-readable program instructions from the network and forwards them to the computer-readable storage media in the respective computing / processing device.

[0087] Computer program instructions used to perform the operations of this disclosure may be assembly instructions, instruction set architecture (ISA) instructions, machine instructions, machine-dependent instructions, microcode, firmware instructions, status setting data, or source code or object code written in any combination of one or more programming languages, including object-oriented programming languages ​​such as Smalltalk, C++, etc., and conventional procedural programming languages ​​such as the "C" language or similar programming languages. The computer-readable program instructions may execute entirely on the user's computer, partially on the user's computer, as a standalone software package, partially on the user's computer and partially on a remote computer, or entirely on a remote computer or server. In cases involving a remote computer, the remote computer may be connected to the user's computer via any type of network—including a local area network (LAN) or a wide area network (WAN)—or may be connected to an external computer (e.g., via the Internet using an Internet service provider). In some embodiments, electronic circuitry, such as programmable logic circuitry, field-programmable gate arrays (FPGAs), or programmable logic arrays (PLAs), is personalized by utilizing the status information of the computer-readable program instructions to implement various aspects of this disclosure.

[0088] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and not to limit it. Although the present invention has been described in detail with reference to the above embodiments, those skilled in the art should understand that modifications or equivalent substitutions can still be made to the specific implementation of the present invention. Any modifications or equivalent substitutions that do not depart from the spirit and scope of the present invention should be covered within the protection scope of the claims of the present invention.

Claims

1. A control method for a modular flexible DC ice-melting device, characterized in that, include: Obtain information on the icing status of the line and the operating information of each DC power unit; Throughout the entire de-icing process, within each control cycle, based on the line icing status information, the de-icing progress index and target de-icing power are calculated. Based on the deviation between the de-icing progress index and the de-icing progress reference index, and the deviation between the current icing thickness and the target icing thickness, the target de-icing power is corrected by thermal inertia compensation. The corrected target de-icing power is then limited and ramped up to obtain the power command. Based on the operating information of each DC power unit, a health factor for each DC power unit is established, and all units are sorted in descending order of health factor. In the sorting, a set of healthy units that can execute power commands is selected, and power commands are assigned to each healthy unit according to the health factor. Based on the power command and output DC voltage allocated to each health unit, the target output current of each health unit is determined; the deviation between the actual output current and the target output current of each health unit is used as the control error, and the duty cycle of each health unit is adjusted through the proportional-integral controller. The trigger phase of each health unit is also adjusted according to the bus ripple level and the power deviation of the health unit to perform adaptive phase-shift triggering for each health unit.

2. The control method for the modular flexible DC ice-melting device according to claim 1, characterized in that, When the ice-melting device submodule fails, a fault reconstruction topology is established based on the modular structure of the ice-melting device. Based on the fault reconstruction topology, the multidimensional health factor is updated and the power command is allocated to each healthy unit according to the updated health factor. The duty cycle and trigger phase of each healthy unit are adaptively adjusted to perform adaptive phase reversal triggering on each healthy unit under the fault reconstruction topology.

3. The control method for the modular flexible DC ice-melting device according to claim 1, characterized in that, The weighted sum of the rate of change of ice thickness and the rate of change of conductor temperature is used as an indicator of the ice melting process, as shown in the following formula: In the formula, To control the cycle Indicators of the ice melting process; To control the cycle The thickness of the ice cover; To control the cycle The temperature of the conductor; To control cycle duration; and These are the weighting coefficients.

4. The control method for the modular flexible DC ice-melting device according to claim 3, characterized in that, Target ice melting power As shown in the following formula: In the formula, , , , , Control cycle The target de-icing power, conductor ice thickness, ambient temperature, wind speed, and conductor temperature. To consider the overall thermal characteristic coefficient, For the length of the transmission line, The target temperature for the conductor. , This is a correction factor.

5. The control method for the modular flexible DC ice-melting device according to claim 4, characterized in that, The corrected target melting power is shown in the following formula: In the formula, To control the cycle The revised target ice melting power; This represents the target value for ice thickness. As a reference indicator for the ice melting process; and This is a correction factor.

6. The control method for the modular flexible DC ice-melting device according to claim 5, characterized in that, The power command obtained by applying the corrected target ice-melting power limit and ramp correction is shown in the following formula: In the formula, For the current control cycle Power command, For the previous control cycle - Power command, This represents the upper limit of power ramp-up.

7. The control method for the modular flexible DC ice-melting device according to claim 1, characterized in that, Based on the operating information of each DC power unit, a multidimensional health factor is established for each DC power unit. The multidimensional health factor simultaneously considers the unit's operating status, current margin, voltage margin, device temperature rise, and cumulative operating load, and all units are sorted in descending order according to the multidimensional health factor. If sorted first The sum of the output power of all units is greater than the power command and is ranked first. If the total output power of -1 unit is less than the power command, then it is ranked first. Each unit constitutes a set of health units; Based on the multidimensional health factor of each health unit in the health unit set, and in combination with the reserved capacity constraint, the power command is allocated to each health unit.

8. The control method for the modular flexible DC ice-melting device according to claim 7, characterized in that, The multidimensional health factor is shown in the following formula: In the formula, To control the cycle No. Health factor of each DC power unit To control the cycle No. The state coefficient of each DC power unit is 1 when the unit is operating at its rated power, a value between 0 and 1 when the unit is operating at derating, and 0 when the unit fails and exits the operation. and The first The maximum allowable output current and maximum output voltage of each DC power unit; , Control cycle No. The output DC voltage and output DC current of each DC power unit; , , These are the weighting coefficients, and + + =1.

9. The control method for the modular flexible DC ice-melting device according to claim 8, characterized in that, The power command is assigned to each health unit, as shown in the following formula: s.t. In the formula, To control the cycle No. Power commands allocated to each healthy unit. To control the cycle Health unit collection, For the current control cycle Power command, To reserve capacity factor, and 0 < <1, For the first The maximum permissible output power of each healthy unit.

10. The control method for the modular flexible DC ice-melting device according to claim 1, characterized in that, The target output current is determined based on the power command and output DC voltage allocated to each health unit; The difference between the output current of each healthy unit and the target output current is used as the control error, and the duty cycle of each healthy unit is adjusted by a proportional-integral controller. The trigger phase of each healthy unit is determined by the basic phase reversal angle and the phase correction amount; among which, the adaptive correction angle is adjusted according to the bus ripple level and the power deviation of the healthy unit.

11. The control method for the modular flexible DC ice-melting device according to claim 10, characterized in that, The trigger phase of the i-th healthy unit is shown in the following formula: In the formula, To control the cycle No. The trigger phase of each healthy unit, To control the cycle The number of internal health units, To control the cycle No. The basic phase shift angle of each healthy unit To control the cycle No. The phase correction of each healthy unit is adaptively adjusted based on the bus current ripple level and unit power deviation.

12. A control system for a modular flexible DC ice-melting device, used to implement the control method for the modular flexible DC ice-melting device according to any one of claims 1 to 11, characterized in that, include: The data acquisition module is used to obtain information on the icing status of the line and the operating information of each DC power unit; The power command generation module is used to calculate the ice melting progress index and the target ice melting power based on the line icing status information in each control cycle during the entire ice melting process. It performs thermal inertia compensation correction on the target ice melting power based on the deviation between the ice melting progress index and the ice melting progress reference index, and the deviation between the current icing thickness and the target icing thickness. It then limits and corrects the target ice melting power after correction to obtain the power command. The power command allocation unit is used to establish the health factor of each DC power unit based on the operating information of each DC power unit, sort all units in descending order of health factor, select the set of healthy units that can execute power commands in the sorting, and allocate power commands to each healthy unit according to the health factor. The trigger command modulation module is used to determine the target output current of each health unit based on the power command and output DC voltage allocated to each health unit; using the deviation between the actual output current and the target output current of each health unit as the control error, the duty cycle of each health unit is adjusted through the proportional-integral controller, and the trigger phase of each health unit is adjusted according to the bus ripple level and the power deviation of the health unit, so as to perform adaptive phase-shift triggering for each health unit.

13. The control system of the modular flexible DC ice-melting device according to claim 12, characterized in that, Also includes: The fault reconfiguration module is used to establish a fault reconfiguration topology based on the modular structure of the ice-melting device when a submodule of the ice-melting device fails. Based on the fault reconstruction topology, the power command allocation unit is called to update the multi-dimensional health factor and the power command is allocated to each health unit according to the updated health factor. The trigger command modulation module is invoked to adaptively adjust the duty cycle and trigger phase of each healthy unit in order to perform adaptive phase-reversed triggering on each healthy unit under the fault reconstruction topology.

14. A terminal, comprising a processor and a storage medium; characterized in that: The storage medium is used to store instructions; The processor is configured to operate according to the instructions to perform the steps of the method according to any one of claims 1-11.

15. A computer-readable storage medium having a computer program stored thereon, characterized in that, When executed by a processor, the program implements the steps of the method according to any one of claims 1-11.

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