Control method and system for composite LC filter of high-voltage converter station and storage medium

Abstract

The invention relates to the technical field of high-voltage commutation, and discloses a control method and system for a composite LC filter of a high-voltage converter station, and a storage medium. According to the method, on the basis of staggered solid / liquid-filled dielectric plates and series hollow inductors in a sealed oil tank, by obtaining a capacitance / inductance adjusting instruction, the filling and pumping volume and speed of insulating liquid and magnetic liquid are controlled according to the absolute value of an adjusting value, and continuous and accurate adjustment of the filtering frequency and reactive power is achieved. The method comprises multiple optimization: monitoring high fluctuation of liquid, synchronously filling, pumping and radiating, balancing efficiency and energy consumption according to an adjusting frequency adaptive circulation speed, and performing reverse linkage cooperative adjustment on a dielectric medium pump and a magnetic liquid pump; and magnetic liquid leakage and insulation abnormity are treated in stages, so that operation is guaranteed. The method solves a traditional adjustment dead zone, does not need a power electronic device, is low in cost, is small in loss, is adaptive to outdoors, and improves the electric energy quality and equipment safety of a converter station.

Description

Technical Field

[0001] This application relates to the technical field of high-voltage converters, and in particular to a control method, system, and storage medium for a composite LC filter in a high-voltage converter station. Background Technology

[0002] High-voltage converter stations are the core hubs of ultra-high-voltage direct current (UHVDC) transmission systems. During operation, their converters generate a large amount of characteristic subharmonics and reactive power. If these are not suppressed and compensated, they will severely impact the power quality of the grid, causing overheating and damage to equipment such as transformers and reactors, and even triggering system voltage fluctuations and oscillations. LC filters, as key supporting equipment in converter stations, utilize the resonant characteristics of capacitors and inductors to specifically suppress harmonics in specific frequency bands, such as the 3rd, 5th, and 7th harmonics, while simultaneously achieving dynamic reactive power compensation to maintain stable converter bus voltage.

[0003] The capacitive branch of an LC filter mainly consists of a capacitor tower. This tower must meet the requirements of high-voltage, high-capacity operation, therefore it is composed of a large number of individual metallized capacitors connected in series and parallel. Considering that converter stations are mostly built in open outdoor areas, the capacitor tower is designed as an outdoor plate-frame structure. The plate frame is made of corrosion-resistant steel, and the individual capacitors are fixed in layers on the plate frame, forming an open arrangement to improve heat dissipation efficiency. However, this structure is significantly affected by the external environment. Changes in temperature, humidity, and pollution levels can easily cause drift in the parameters of individual capacitors, thus affecting the equivalent capacitance of the entire capacitor tower and potentially impacting the filter's resonant characteristics.

[0004] Existing high-voltage converter station LC filters mostly adopt a group-switching control method, achieving specific harmonic suppression and reactive power regulation based on a fixed LC topology. Since the filter's resonant frequency is fixed by the LC element parameters, once the topology is determined, the number of harmonics it can suppress cannot be flexibly adjusted, making it difficult to adapt to dynamic changes in the grid's harmonic spectrum. Simultaneously, under the group-switching method, reactive power regulation is achieved by switching the entire filter group on or off, with fixed step values ​​for adjustment, resulting in a significant dead zone and preventing continuous and precise compensation. When the converter station load fluctuates drastically or the grid harmonic composition changes, the filter cannot match the system demand in real time, easily leading to incomplete harmonic suppression and reactive power compensation deviations, resulting in poor power quality control. Summary of the Invention

[0005] To enable continuous and precise adjustment of filter parameters, this application provides a control method, system, and storage medium for a composite LC filter in a high-voltage converter station.

[0006] In a first aspect, this application provides a control method for a composite LC filter in a high-voltage converter station, employing the following technical solution: A control method for a composite LC filter in a high-voltage converter station includes the following steps: A hollow inductor, interlocking solid dielectric plates, and liquid-filled dielectric plates are installed inside a sealed oil tank, with the solid dielectric plates and liquid-filled dielectric plates arranged alternately; a second high-voltage terminal is connected to the solid dielectric plate; the liquid-filled dielectric plate is connected in series with the hollow inductor and then connected to the first high-voltage terminal; a discharge resistor is connected in parallel between the liquid-filled dielectric plate and the solid dielectric plate; and a high-voltage fuse is connected in series between the solid dielectric plate and the second high-voltage terminal. Obtain a capacitance adjustment command and extract the capacitance adjustment value from it; respond to the capacitance adjustment command by filling or extracting insulating liquid into the sealed oil tank, wherein the volume and rate of change of the filled or extracted insulating liquid are positively correlated with the absolute value of the capacitance adjustment value; obtain an inductance adjustment command and extract the inductance adjustment value from it; respond to a liquid filling command by filling or extracting magnetic liquid into the liquid-filled dielectric plate, wherein the volume and rate of change of the filled or extracted magnetic liquid are positively correlated with the absolute value of the inductance adjustment value.

[0007] By adopting the above technical solution, continuous and precise parameter adjustment is achieved. Responding to capacitor and inductor adjustment commands, by filling / extracting the corresponding liquid, large-scale, continuous and precise changes in filter frequency and reactive power can be completed within seconds. This adapts to dynamic changes in the power grid harmonic spectrum and load fluctuation scenarios, solving the dead zone problem of traditional group switching. The cost is low, only requiring improvements to the plates and the addition of pumps, valves and cavities to ordinary capacitors. No power electronic devices are needed, and the cost is at least 70% lower than that of SVG equipment of the same power. At the same time, it avoids high-frequency harmonic interference from power electronic components, and the lightning protection capability is greatly improved. The loss is low and the adaptability is strong. It is essentially a traditional capacitor structure with no switching losses and high efficiency. Furthermore, the integrated design avoids the environmental interference problems of outdoor frame structures, making it suitable for the outdoor operation requirements of high-voltage converter stations.

[0008] Optionally, the method further includes the following steps: Obtain the insulating liquid level in the sealed oil tank; Calculate the first fluctuation range value of the insulating liquid level height within the set first calculation time; If the first fluctuation amplitude value is within the preset first liquid level fluctuation range, then insulating liquid is filled into the sealing oil tank while insulating liquid is extracted from the sealing oil tank, and the volume of insulating liquid filled in is the same as the volume of insulating liquid extracted. Obtain the height of the magnetic fluid level inside the filled medium plate; Calculate the second fluctuation amplitude value of the magnetic fluid surface height within the set second calculation time; If the second fluctuation amplitude value is within the preset second liquid level fluctuation range, magnetic liquid is injected into the filling medium plate while magnetic liquid is extracted from the filling medium plate, and the volume of the injected magnetic liquid is the same as the volume of the extracted magnetic liquid.

[0009] By adopting the above technical solution, and by monitoring the fluctuation of liquid level, insulating liquid and magnetic liquid are simultaneously pumped and charged in equal amounts within a specific range, thereby achieving liquid circulation and efficient heat dissipation.

[0010] Optionally, the method further includes the following steps: Calculate the time interval between the most recent capacitor adjustment commands; calculate the capacitor adjustment frequency based on the multiple time intervals corresponding to the capacitor adjustment commands. The circulation speed of the insulating liquid being filled and extracted from the sealed oil tank is adjusted according to the positive correlation between the capacitor adjustment frequency and the frequency. The higher the capacitor adjustment frequency, the faster the circulation speed of the insulating liquid, and the lower the capacitor adjustment frequency, the slower the circulation speed of the insulating liquid. Calculate the time interval between the most recent inductor adjustment commands; calculate the inductor adjustment frequency based on the multiple time intervals corresponding to the inductor adjustment commands. The circulation speed of the magnetic fluid being filled and extracted in the fluid-filled medium plate is positively correlated with the inductor adjustment frequency. The higher the inductor adjustment frequency, the faster the circulation speed of the magnetic fluid, and the lower the inductor adjustment frequency, the slower the circulation speed of the magnetic fluid.

[0011] By adopting the above technical solution, the liquid circulation speed is positively correlated with the frequency of capacitor and inductor adjustment, with higher frequency resulting in faster circulation and lower frequency resulting in slower circulation, thus balancing heat dissipation efficiency and energy consumption.

[0012] Optionally, a magnetic fluid is used as the medium, and the hollow part of the magnetic fluid storage unit is connected to the hollow part inside the liquid-filled medium plate through a magnetic fluid pump and a magnetic fluid pipeline valve; the magnetic fluid storage unit and the hollow part inside the liquid-filled medium plate are connected through a magnetic fluid pipeline return pipe to achieve air pressure balance; the liquid inlet is located at a low position of the magnetic fluid storage unit.

[0013] By adopting the above technical solution, using magnetic fluid as the medium, the magnetic fluid storage unit and the filling medium plate are connected by a magnetic fluid pump and a magnetic fluid pipeline valve. The magnetic fluid pipeline return pipe balances the air pressure, and the low-position liquid inlet assists the liquid flow, ensuring stable delivery of magnetic fluid and inductance adjustment.

[0014] Optionally, an insulating liquid is used as the medium, and the sealing oil tank and the dielectric oil tank are connected through a dielectric pump and a dielectric pipeline valve. The cavity between the sealing oil tank and the dielectric oil tank is connected through a dielectric pipeline return pipe to balance the air pressure.

[0015] By adopting the above technical solution, using insulating liquid as the medium, the two oil tanks are connected by a dielectric pump and a dielectric pipeline valve to achieve liquid flow control. The return gas pipe of the dielectric pipeline balances the gas pressure, ensuring stable delivery of insulating liquid and facilitating precise adjustment of capacitance.

[0016] Optionally, the method further includes the following steps: In response to the start command of the dielectric pump or the magnetic fluid pump, the dielectric pump and the magnetic fluid pump are set to reverse linkage: when the dielectric pump starts the pumping action, the magnetic fluid pump starts the pumping action; when the dielectric pump starts the pumping action, the magnetic fluid pump starts the pumping action.

[0017] By adopting the above technical solution, the dielectric pump and the magnetic fluid pump are linked in opposite directions, with the pumping and pumping actions being opposite, so as to realize the coordinated adjustment of capacitance and inductance, which helps to accurately control the filtering frequency and reactive power.

[0018] Optionally, the method further includes the following steps: Upon receiving a first stop pumping command, in response to the first stop pumping command, stop pumping and extracting the magnetic fluid, and control the filling medium plate to close. Calculate the magnetic fluid level drop within the set detection time. If the magnetic fluid reduction value is within the preset first leakage range, a magnetic fluid leakage warning is issued; the insulating fluid pipeline is connected to the magnetic fluid pipeline through a one-way valve, and the insulating fluid is pumped into the filling medium plate through the insulating fluid pipeline and the magnetic fluid pipeline; a reduction comparison value is calculated based on the magnetic fluid reduction value and a preset reduction reference value, and the pumping speed of the insulating fluid is adjusted according to the positive correlation of the reduction comparison value. The larger the reduction comparison value, the faster the pumping speed of the insulating fluid, and the smaller the reduction comparison value, the slower the pumping speed of the insulating fluid. If the magnetic fluid drop value is within the preset second leakage range, a second stop pumping command is generated; the magnetic fluid in the filling medium plate is extracted. The second leakage range is located within the first leakage range, and the value within the second leakage range is greater than other values ​​within the first leakage range.

[0019] By adopting the above technical solution, leakage is handled according to its range. For small leaks, a warning is given and the insulation fluid replenishment rate is adjusted according to the comparison value. For large leaks, the pump is stopped and the magnetic fluid is pumped out, ensuring the safety and adjustment capability of the equipment operation.

[0020] Optionally, the method further includes the following steps: In response to the second stop pumping command, the extraction and pumping of insulating liquid are stopped, and the filling medium plate and the sealing oil tank are closed. The insulation and volume parameters of the insulating liquid in the sealed oil tank were tested. If the insulation parameters are within the preset first insulation range, an insulation performance reduction warning is issued; insulating liquid is pumped into the sealed oil tank through the insulating liquid pipeline; the insulation comparison value is calculated based on the insulation parameters and the preset insulation reference parameters; the pumping speed of the insulating liquid is adjusted according to the negative correlation of the insulation comparison value. The larger the insulation comparison value, the slower the pumping speed of the insulating liquid; the smaller the insulation comparison value, the faster the pumping speed of the insulating liquid. If the insulation parameters are within the preset second insulation range, an insulation performance damage warning will be issued; the insulating liquid in the sealing oil tank will be evacuated and discharged through the insulating liquid pipeline, and insulating liquid corresponding to the volume parameters will be injected into the sealing oil tank; The second insulation range is located within the first insulation range, and the values ​​within the second insulation range are less than the other values ​​within the first insulation range.

[0021] By adopting the above technical solutions, insulation performance is treated according to different levels. When the insulation level is slightly reduced, a prompt is given and the replenishment rate is adjusted according to the comparison value. When the insulation is severely damaged, the fluid is replaced to ensure the insulation performance and safe operation of the equipment.

[0022] Secondly, this application provides a control system for a composite LC filter in a high-voltage converter station, employing the following technical solution: A control system for a composite LC filter in a high-voltage converter station includes a processor, wherein the processor executes the steps of the control method for the composite LC filter in a high-voltage converter station as described in any one of the preceding claims.

[0023] Thirdly, this application provides a storage medium, which adopts the following technical solution: A storage medium storing a program, which, when executed by a processor, implements the steps of the control method for the composite LC filter of a high-voltage converter station as described above.

[0024] In summary, this application includes at least one of the following beneficial technical effects: Through the dynamic linkage of insulating liquid and capacitance, as well as magnetic fluid and inductance, the volume and speed of liquid filling or extraction change synchronously with the adjustment value. Within seconds, continuous dead-zone-free adjustment of filter frequency and reactive power can be achieved, adapting to scenarios of converter station load fluctuations and dynamic changes in grid harmonic spectrum, avoiding the dead-zone problem of traditional group switching. At the same time, the reverse linkage design of dielectric pump and magnetic fluid pump allows capacitance and inductance to be adjusted in reverse in synergy, accurately locking the target resonant frequency, and taking into account the dual requirements of harmonic suppression and reactive power compensation.

[0025] Without relying on power electronic devices, it only improves the plates of ordinary capacitors and adds pumps, valves and cavities. The hardware cost is at least 70% lower than that of SVG equipment of the same power, and also saves the complicated operation and maintenance work of power electronic components. The design without power electronic devices not only eliminates switching losses and high-frequency interference, making the operating efficiency reach more than 99.9%, but also significantly improves the lightning protection capability. In addition, the integrated structure of the sealed oil tank can stably adapt to the complex outdoor environment of the converter station and extend the service life of the equipment.

[0026] Through scientific heat dissipation control, liquid circuit design, and fault classification handling, the efficient and safe operation of the equipment is further ensured. For heat dissipation, a "same-volume charging and pumping" circulation is initiated based on liquid level fluctuations, and the circulation speed is dynamically adapted according to the adjustment frequency. This efficiently removes heat, preventing localized overheating, and balances energy consumption. In the liquid circuit design, the low-position inlet of the magnetic fluid pipeline utilizes gravity to aid flow, the return gas pipe balances air pressure, and the insulating fluid pipeline ensures sealed delivery, providing stable medium support for parameter adjustment. For fault handling, graded measures are taken for magnetic fluid leakage and abnormal insulation performance. For minor faults, leakage is dynamically repaired or the medium is replenished; for major faults, the pump is stopped and the liquid drained or the medium replaced promptly, minimizing the impact of the fault. Attached Figure Description

[0027] Figure 1 This is a top view schematic diagram of a composite LC filter for a high-voltage converter station.

[0028] Figure 2 This is a flowchart illustrating the control method of a composite LC filter in a high-voltage converter station.

[0029] Reference numerals in the attached drawings: 1. First high-voltage terminal; 2. Second high-voltage terminal; 3. Sealed oil tank; 4. Solid dielectric plate; 5. Liquid-filled dielectric plate; 6. Magnetic fluid; 7. Electrolytic oil tank; 8. Electrolytic pump; 9. Magnetic fluid pump; 10. Magnetic fluid pipeline valve; 11. Electrolytic pipeline valve; 12. Magnetic fluid pipeline return pipe; 13. Electrolytic pipeline return pipe; 14. Hollow inductor; 15. Discharge resistor; 16. High-voltage fuse; 17. Magnetic fluid storage unit. Detailed Implementation

[0030] The embodiments of this application are described in detail below, and examples of the embodiments are shown in the accompanying drawings.

[0031] In the description of this specification, the references to "certain embodiments," "one embodiment," "some embodiments," "illustrative embodiment," "example," "specific example," or "some examples" refer to specific features, structures, materials, or characteristics described in connection with the described embodiment or example, which are included in at least one embodiment or example of this application. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0032] A composite LC filter for a high-voltage converter station, referenced Figure 1The system includes a sealed oil tank 3, inside which are a hollow inductor 14, a solid dielectric plate 4 with interlocking and staggered plates, and a liquid-filled dielectric plate 5. The solid dielectric plate 4 is directly connected to the second high-voltage terminal 2, and the liquid-filled dielectric plate 5 is connected in series with the hollow inductor 14 and then connected to the first high-voltage terminal 1. At the same time, a discharge resistor 15 is connected in parallel between the two dielectric plates, and a high-voltage fuse 16 is connected in series between the solid dielectric plate 4 and the second high-voltage terminal 2, forming a complete filter electrical circuit.

[0033] The liquid storage and regulation system is divided into two paths: one is an insulating liquid system equipped with a dielectric oil tank 7 of the same volume as the sealed oil tank 3 (both filled with castor oil). The two tanks are connected by a dielectric pump 8 and a dielectric pipeline valve 11, and are connected across a dielectric pipeline return air pipe 13 to balance the air pressure in the cavity, thereby achieving the filling and pumping regulation of the insulating liquid. The other path is a magnetic liquid system 6, which is equipped with a magnetic liquid storage unit 17 for storing magnetic liquid (a mixture of elemental iron powder, suspension agent, and insulating oil in a volume ratio of 10:1:15). It is connected to the hollow part inside the filling medium plate 5 through a magnetic liquid pump 9 and a magnetic liquid pipeline valve 10, and is connected across a magnetic liquid pipeline return air pipe 12 to balance the air pressure. The liquid inlet of the magnetic liquid storage unit 17 is located at a lower position to assist the liquid flow.

[0034] Based on the aforementioned composite LC filter for a high-voltage converter station, this application discloses a control method for the composite LC filter in a high-voltage converter station, referring to... Figure 1 and Figure 2 It includes the following steps: The controller receives capacitor adjustment commands from the high-voltage converter station monitoring system in real time. These commands are generated based on the converter station's current reactive power demand and the grid voltage stability target. The controller parses the capacitor adjustment commands and extracts the core capacitor adjustment value. If the capacitor adjustment value is positive, it means that the equivalent capacitance in the sealed oil tank 3 needs to be increased to improve reactive power compensation capability; if it is negative, it means that the equivalent capacitance needs to be decreased to reduce reactive power output.

[0035] The controller sends action commands to the dielectric pump 8 and the dielectric pipeline valve 11 based on the sign and absolute value of the capacitance adjustment value. When an increase in capacitance is required, the controller opens the dielectric pipeline valve 11 and simultaneously starts the dielectric pump 8 to rotate forward, pumping castor oil from the dielectric oil tank 7 into the sealed oil tank 3. At this time, the volume of insulating liquid injected and the rate of volume change are positively correlated with the absolute value of the capacitance adjustment value. For example, when the absolute value of the capacitance adjustment value is 20% (i.e., a 20% increase in capacitance is required), the injected volume is 20% of the rated adjustment volume of the sealed oil tank 3, and the rate of volume change is set to 0.5 L / s. If the absolute value of the adjustment value increases to 40%, the injected volume increases accordingly to 40%, and the rate of change increases synchronously to 1 L / s, ensuring rapid response of capacitance adjustment requirements. When a decrease in capacitance is required, the controller reverses the dielectric pump 8 to pump castor oil from the sealed oil tank 3 into the dielectric oil tank 7. The extracted volume and rate of change also follow the principle of "positive correlation with absolute value". During this process, the return air pipe 13 of the dielectric pipeline balances the air pressure in the cavity of the sealing oil tank 3 and the dielectric oil tank 7 in real time, so as to avoid negative pressure or excessive pressure in the pipeline caused by liquid flow and ensure stable delivery of insulating liquid.

[0036] While performing capacitor adjustment, the controller simultaneously receives inductor adjustment commands. These commands are generated based on the current harmonic spectrum analysis results of the power grid. For example, to suppress the 3rd and 5th harmonics, the inductance needs to be adjusted to match the capacitor and form the target resonant frequency. The controller parses the commands and extracts the inductance adjustment values. Positive values ​​indicate that the equivalent inductance of the liquid-filled dielectric plate 5 needs to be increased, while negative values ​​indicate that the inductance needs to be decreased.

[0037] The controller sends action commands to the magnetic fluid pump 9 and the magnetic fluid pipeline valve 10 based on the sign and absolute value of the inductance adjustment value. When the inductance needs to be increased, the magnetic fluid pipeline valve 10 is opened, and the magnetic fluid pump 9 is started to rotate forward, drawing the magnetic fluid 6 from the magnetic fluid storage unit 17 into the hollow part inside the filling medium plate 5. The filling volume and the rate of volume change of the magnetic fluid 6 are positively correlated with the absolute value of the inductance adjustment value. For example, when the absolute value of the inductance adjustment value is 15%, the filling volume is 15% of the rated adjustment volume of the hollow part of the filling medium plate 5, and the rate is 0.3L / s. When the absolute value of the adjustment value increases to 30%, the volume and rate increase to 30% and 0.6L / s respectively. By increasing the amount of magnetic fluid 6, the magnetic conductivity of the filling medium plate 5 is improved, thereby increasing the equivalent inductance. When the inductance needs to be decreased, the magnetic fluid pump 9 is reversed, drawing the magnetic fluid 6 from the filling medium plate 5 into the storage unit. The drawing parameters also follow the principle of "positive correlation of absolute value". During this process, the return air pipe 12 of the magnetic fluid pipeline balances the air pressure in real time. Since the inlet of the magnetic fluid storage unit 17 is located at a low position, the magnetic fluid 6 is assisted by gravity to flow, reducing the starting load of the magnetic fluid pump 9 and ensuring the stability and continuity of the magnetic fluid 6 delivery.

[0038] This control method can complete large-scale, continuous, and precise changes in filter frequency and reactive power within seconds. For example, in the event of a sudden 5th harmonic exceeding the limit at the converter station, after receiving the inductor adjustment command, the controller can complete the filling of the magnetic fluid 6 within 3 seconds, adjusting the inductance to the resonant value matching the current capacitor, thus effectively suppressing the 5th harmonic. Simultaneously, the volume of insulating fluid is adjusted synchronously according to reactive power demand to ensure accurate reactive power compensation. Furthermore, this method does not rely on power electronic devices; it is achieved simply by improving the traditional capacitor plate structure and adding liquid transport components. The hardware cost is at least 70% lower than that of SVG equipment of the same power, and it eliminates the switching losses and high-frequency interference of power electronic components, achieving an operating efficiency of over 99.9%. The sealed integral structure also avoids the parameter drift problem of traditional outdoor plate-type capacitor towers affected by temperature, humidity, and pollution levels, perfectly adapting to the complex outdoor operating environment of high-voltage converter stations.

[0039] Based on the above-mentioned adjustment of capacitor and inductor parameters, a liquid circulation heat dissipation control step is further added. By monitoring the liquid level fluctuation state of the insulating liquid and magnetic liquid 6 in real time, a synchronous charging and pumping cycle is triggered to achieve efficient heat dissipation during equipment operation. The specific method also includes the following steps: Based on the filter's rated operating power and the physical properties (such as viscosity and coefficient of thermal expansion) of the insulating liquid (castor oil) and magnetic fluid 6, a first liquid level fluctuation range and a second liquid level fluctuation range are preset. The first liquid level fluctuation range is set for the insulating liquid in the sealed oil tank 3, for example, 0.5mm-2mm; when the liquid level fluctuation within this range per unit time, it is determined that circulating cooling needs to be activated. The second liquid level fluctuation range is set for the magnetic fluid 6 in the filling medium plate 5, for example, 0.3mm-1.5mm. Magnetic fluid 6 has a higher viscosity, and its fluctuation threshold is slightly lower than that of the insulating liquid. Simultaneously, a first calculation time and a second calculation time are both set to 30 seconds.

[0040] The insulating liquid level sensor is installed on the side wall of the sealed oil tank 3, with the detection end facing the middle of the insulating liquid level to avoid the electrode plate blocking it; the magnetic liquid level sensor is embedded in the reserved interface at the top of the liquid-filled medium plate 5 to ensure that the detection signal penetrates the medium plate wall and is not affected by the magnetic field of the magnetic liquid 6.

[0041] The controller receives real-time data from the insulating liquid level sensor at a frequency of 1 time / second. Within a set first calculation period (30 seconds), it extracts the highest and lowest liquid level values ​​during that period. The liquid level fluctuation amplitude is then calculated using the formula: First fluctuation amplitude = Highest liquid level value - Lowest liquid level value. For example, if the highest liquid level is 500.8 mm and the lowest is 499.2 mm within 30 seconds, the first fluctuation amplitude value is 1.6 mm.

[0042] The controller compares the calculated first fluctuation amplitude value with the preset first liquid level fluctuation range: If the first fluctuation amplitude value is within this range, such as 1.6mm as mentioned above, it is determined that the insulating liquid in the sealing oil tank 3 is experiencing thermal convection fluctuations due to heat generation during equipment operation, and circulation cooling needs to be initiated. At this time, the controller sends a coordinated command to the dielectric pump 8 and the dielectric pipeline valve 11: controlling the dielectric pipeline valve 11 to open bidirectionally, that is, simultaneously connecting the inlet and outlet channels of the sealing oil tank 3 and the dielectric oil tank 7, and starting the dielectric pump 8 to enter the bidirectional delivery mode. The low-temperature insulating liquid in the dielectric oil tank 7 is charged into the sealing oil tank 3 at the same flow rate (e.g., 1L / min), while an equal amount of high-temperature insulating liquid is drawn from the sealing oil tank 3 into the dielectric oil tank 7. The volume of liquid charged and drawn is kept consistent in real time to ensure that the total volume of insulating liquid in the sealing oil tank 3 remains unchanged, avoiding the influence of liquid level changes on the capacitance parameters.

[0043] If the first fluctuation amplitude value is below 0.5mm (liquid level is stable, heat dissipation demand is low) or above 2mm (abnormal liquid level fluctuation, possibly indicating leakage or equipment failure), the circulating heat dissipation will not be activated. When the value is below the threshold, the system will remain in standby mode. When the value is above the threshold, an abnormal alarm will be triggered to prompt staff to troubleshoot the fault.

[0044] While monitoring the insulating liquid, the controller simultaneously receives real-time data from the magnetic liquid level sensor. Within the set second calculation period (30s), the highest and lowest magnetic liquid level values ​​are extracted using the same method, and the second fluctuation amplitude value is calculated. For example, if the highest level of magnetic liquid 6 is 300.6mm and the lowest is 300.1mm within 30s, the second fluctuation amplitude value is 0.5mm.

[0045] The controller compares the second fluctuation amplitude value with the preset second liquid level fluctuation range: If the second fluctuation amplitude value is within this range, such as 0.5mm as mentioned above, it is determined that the magnetic liquid 6 in the filling medium plate 5 is fluctuating due to inductive heating, and the circulation of magnetic liquid 6 for heat dissipation is initiated. The controller sends instructions to the magnetic liquid pump 9 and the magnetic liquid pipeline valve 10: open the bidirectional channel of the magnetic liquid pipeline valve 10, start the magnetic liquid pump 9 to fill the filling medium plate 5 with the low-temperature magnetic liquid 6 in the magnetic liquid storage unit 17 at a constant flow rate (e.g., 0.8L / min), and at the same time extract an equal amount of high-temperature magnetic liquid 6 from the filling medium plate 5 into the magnetic liquid storage unit 17. The filling and extraction volumes are strictly equal to ensure that the total amount of magnetic liquid 6 in the filling medium plate 5 is stable and to avoid deviation of the inductance due to changes in liquid level. In addition, because the liquid inlet of the magnetic liquid storage unit 17 is located at a low position, the low-temperature magnetic liquid 6 can flow into the filling medium plate 5 with the assistance of gravity, reducing the operating load of the magnetic liquid pump 9 and improving the circulation efficiency.

[0046] If the second fluctuation amplitude value is lower than 0.3mm or higher than 1.5mm, the circulating heat dissipation will not be activated. When it is lower than the threshold, it will be in standby mode. When it is higher than the threshold, the magnetic fluid 6 system will trigger an abnormal alarm.

[0047] During the circulation and heat dissipation process of the insulating liquid and magnetic fluid 6, the controller monitors the liquid level changes of the sealing oil tank 3 and the filling medium plate 5 in real time. Data feedback from the liquid level sensor ensures that the filling and pumping volume deviation is ≤±2%. If the deviation exceeds this range, the pump speed is adjusted to correct it. Simultaneously, the controller monitors the liquid temperature in real time. Temperature sensors installed in the dielectric oil tank 7 and the magnetic fluid storage unit 17 monitor the temperature difference of the circulating liquid. When the temperature difference is ≤2℃ (heat dissipation effect meets the standard), the pump's operating flow rate is automatically reduced (e.g., to 0.5L / min), balancing heat dissipation and energy consumption control. Furthermore, the circulation and heat dissipation action does not interfere with capacitor and inductor adjustment commands. If a parameter adjustment command is received during circulation, the controller prioritizes the parameter adjustment and resumes circulation and heat dissipation after the adjustment is completed.

[0048] Through the above steps, the heat generated during equipment operation can be transferred to an external storage tank by utilizing the circulating flow of insulating liquid and magnetic liquid 6, thereby achieving efficient heat dissipation and avoiding changes in the physical properties of the liquid due to local overheating.

[0049] To ensure efficient heat dissipation while reducing energy consumption, the following steps are included: The number of instruction samples and the frequency calculation cycle for calculating the adjustment frequency are set. The number of instruction samples is uniformly set to 5 times, and the frequency calculation cycle is set to 10 minutes. At the same time, the adjustment range of the circulation speed is preset: the circulation speed range of the insulating liquid is 0.3L / min-2L / min, matching the rated power of the dielectric pump 8; the circulation speed range of the magnetic fluid 6 is 0.2L / min-1.5L / min, adapting to the high viscosity characteristics of the magnetic fluid 6. A positive correlation mapping table between the adjustment frequency and the circulation speed is established. For example, when the capacitor adjustment frequency is 0.5 times / min, the corresponding insulating liquid circulation speed is 0.5L / min; when the frequency is increased to 2 times / min, the circulation speed is simultaneously increased to 1.2L / min.

[0050] The controller's instruction recording function is debugged to ensure that each time a capacitor adjustment instruction or inductor adjustment instruction is received from the high-voltage converter station, the instruction reception timestamp is automatically recorded, and the time data of the five most recent instructions are stored in chronological order to form independent capacitor instruction time sequences and inductor instruction time sequences, thus avoiding instruction data loss or misalignment.

[0051] The controller monitors the capacitor adjustment command time series in real time. Once the sequence is full of the timestamps of the five most recent capacitor adjustment commands, it calculates four time interval values ​​sequentially using the formula "later command time - previous command time". For example, if the timestamps of the five commands are 10:00:00, 10:01:30, 10:03:00, 10:04:00, and 10:05:30, the corresponding time intervals are 90s, 90s, 60s, and 90s, respectively.

[0052] Based on the four time interval values ​​mentioned above, first calculate the average time interval using the formula: Average time interval = Total time interval / Number of intervals. Then, convert the adjustment frequency to the capacitor adjustment frequency using the formula: Adjustment frequency = 60s / Average time interval. Taking the example above, the total time interval is 90 + 90 + 60 + 90 = 330s, the average time interval is 330 / 4 = 82.5s, and the capacitor adjustment frequency is approximately 60 / 82.5 ≈ 0.73 times / min.

[0053] The controller compares the calculated capacitor adjustment frequency with a preset mapping table of adjustment frequency and circulation speed to determine the corresponding insulating liquid circulation speed. If the capacitor adjustment frequency is 0.73 times / min, which falls between 0.5 times / min (corresponding to 0.5 L / min) and 1 time / min (corresponding to 0.8 L / min), the target circulation speed is calculated through linear interpolation: 0.5 + (0.73 - 0.5) × (0.8 - 0.5) / (1 - 0.5) ≈ 0.64 L / min. Subsequently, the controller sends a speed adjustment command to the dielectric pump 8, adjusting the insulating liquid circulation speed from the current value to 0.64 L / min. If the current circulation speed is lower than the target value, the speed of the dielectric pump 8 is increased; if it is higher than the target value, the speed is decreased to ensure precise matching between the circulation speed and the adjustment frequency. When subsequent capacitor adjustment commands are updated, the controller repeats the above calculation and adjustment steps to achieve dynamic updates of the circulation speed.

[0054] Consistent with the capacitor adjustment frequency calculation logic, the controller monitors the inductor command time sequence. Once the timestamps of the five most recent inductor adjustment commands are stored, it calculates four time interval values. For example, if the five inductor command timestamps are 10:00:10, 10:02:10, 10:04:40, 10:06:10, and 10:08:10, the corresponding time intervals are 120s, 150s, 90s, and 120s.

[0055] Calculate the average time interval: 120+150+90+120=480s, average time interval = 480 / 4 = 120s, then convert the inductor adjustment frequency = 60 / 120 = 0.5 times / min.

[0056] Based on the mapping table between adjustment frequency and circulation speed, the controller determines that the circulation speed of the magnetic fluid 6 corresponding to an inductor adjustment frequency of 0.5 times / min is 0.4 L / min. It then sends a speed command to the magnetic fluid pump 9 to adjust the circulation speed of the magnetic fluid 6 to 0.4 L / min. Due to the high viscosity of the magnetic fluid 6, a slow transition mechanism needs to be implemented during speed adjustment. For example, when increasing from the current 0.3 L / min to 0.4 L / min, the speed is adjusted gradually in three steps, with a 2-second interval between each adjustment, to avoid instability in the flow of the magnetic fluid 6 in the pipeline due to sudden changes in speed. Similarly, when subsequent inductor adjustment commands are updated, the calculation and adjustment process is repeated to ensure that the circulation speed of the magnetic fluid 6 dynamically changes with the adjustment frequency.

[0057] During the dynamic adjustment of the circulation speed, if the adjustment frequency is too high, such as when the capacitor adjustment frequency reaches 3 times / min, exceeding the upper limit of the mapping table, the circulation speed will be automatically locked to the preset maximum value: 2L / min for insulating liquid and 61.5L / min for magnetic liquid, to avoid pump overload operation; if the adjustment frequency is too low, such as when the inductor adjustment frequency is below 0.1 times / min, the circulation speed will be reduced to the preset minimum value: 0.3L / min for insulating liquid and 60.2L / min for magnetic liquid, to ensure basic heat dissipation requirements.

[0058] During the dynamic adjustment of the cycle speed, if a capacitor / inductance parameter adjustment command is received during the cycle speed adjustment process, the controller will prioritize the parameter adjustment, such as adjusting the capacitance / inductance by filling or pumping liquid. After the parameter adjustment is completed, the cycle speed adjustment will be resumed to avoid conflict between the two and cause parameter deviation.

[0059] During the dynamic adjustment of the circulation speed, the energy consumption is monitored by the current sensors of the dielectric pump 8 and the magnetic fluid pump 9. If the energy consumption exceeds the preset threshold after the circulation speed has been running for 10 minutes, such as the energy consumption of the insulating liquid circulation exceeding 50W, and the current heat dissipation effect meets the standard with a liquid temperature difference ≤3℃, then the circulation speed is appropriately reduced, such as by 10%, based on the positive correlation between the adjustment frequency and the circulation speed, to achieve a further balance between heat dissipation and energy consumption.

[0060] Through the above steps, the liquid circulation speed can be precisely matched with the parameter adjustment requirements of the filter. When the grid harmonics or reactive power fluctuate frequently, i.e. when the adjustment frequency is high, the circulation speed is automatically increased to enhance heat dissipation and avoid overheating of the equipment. When the grid condition is stable, i.e. when the adjustment frequency is low, the circulation speed is reduced to reduce energy consumption, ultimately achieving the optimal balance between heat dissipation efficiency and energy consumption cost.

[0061] This embodiment designs a reverse linkage control mechanism for the coordinated operation logic of the dielectric pump 8 and the magnetic fluid pump 9. The specific method also includes the following steps: Among them, the dielectric pump 8 rotates forward to pump in insulating liquid and reverses to pump out, and the magnetic liquid pump 9 rotates forward to pump in magnetic liquid 6 and reverses to pump out. The linkage program is preset to ensure that the start-up time difference between the two pumps is ≤0.2s and the flow deviation is ≤5%. At the same time, the air pressure in the pipeline is balanced through the return air pipe to ensure stable liquid delivery.

[0062] During coordinated execution, regardless of whether the trigger source is the start command of the dielectric pump 8 or the magnetic fluid pump 9, the two pumps always maintain opposite operating directions: if the dielectric pump 8 starts the pumping action to increase the insulating liquid and improve the capacitance, the magnetic fluid pump 9 simultaneously starts the pumping action to reduce the magnetic fluid 6 and reduce the inductance; if the dielectric pump 8 starts the pumping action to reduce the capacitance, the magnetic fluid pump 9 simultaneously starts the pumping action to increase the magnetic fluid 6 and improve the inductance.

[0063] During the process, flow rate and liquid level are monitored in real time via flow meters and level sensors, and automatic correction is performed when deviations exceed limits. In case of pump failure or when the adjustment meets the standards, both pumps stop operating synchronously to avoid abnormal parameters. This solution achieves precise reverse coordination of capacitance and inductance, ensuring stable filtering frequency.

[0064] This embodiment addresses the potential leakage problem of the magnetic fluid 6 inside the liquid-filled dielectric plate 5, and specifically includes the following steps: Based on the sealing performance of the filling medium plate 5 and the viscosity characteristics of the magnetic fluid 6, two leakage ranges are preset. The first leakage range (small leakage) is set at 0.1mm-0.5mm, meaning the decrease in magnetic fluid level within this range during the detection period is small and does not affect the core adjustment. The second leakage range (large leakage) is set at 0.5mm-1.0mm, indicating a larger leakage that requires urgent handling to avoid equipment damage. It is clearly stated that the second leakage range is completely contained within the first leakage range, only with a higher upper limit. The detection period is set to 60 seconds to balance the accuracy of leakage detection with timely response, avoiding misjudgments due to short-term fluid level fluctuations. A reference value for the decrease, such as 0.3mm, is preset as a benchmark for calculating the decrease comparison value, reflecting a moderate degree of leakage.

[0065] The closing valve of the filling medium plate 5 is debugged. The closing valve is an electromagnetic shut-off valve with a response time of ≤0.5s, ensuring that the connection between the magnetic liquid 6 pipeline and the filling medium plate 5 can be quickly cut off after receiving the closing command. A one-way valve is installed at the connection node between the insulating liquid pipeline and the magnetic liquid 6 pipeline. The one-way valve is magnetically resistant and has an opening pressure of ≤0.1MPa to prevent the insulating liquid from flowing back into the magnetic liquid storage unit 17 and contaminating the magnetic liquid. At the same time, the magnetic liquid level sensor in the filling medium plate 5 is calibrated. The magnetic liquid level sensor is a magnetically resistant capacitive type with a detection error of ≤±0.05mm to ensure accurate liquid level data acquisition.

[0066] When the controller receives the first stop pumping command, the trigger scenarios include: the magnetic fluid 6 has been regulated, the level sensor has initially detected an abnormal level, and a temporary shutdown command has been issued by the converter station. The controller immediately sends a shutdown command to the magnetic fluid pump 9 to terminate the extraction and pumping of the magnetic fluid 6. At the same time, a closing command is sent to the electromagnetic shut-off valve of the filling medium plate 5. The valve closes within 1 second, completely isolating the filling medium plate 5 from the magnetic fluid 6 pipeline to prevent leakage from spreading to other areas of the pipeline.

[0067] The controller immediately initiates the leakage detection process after the valve is closed. Using the magnetic fluid level at the moment of closure as the initial height value (e.g., 300.00 mm), magnetic fluid level data is collected every 5 seconds within a set 60-second detection period. The final height value is the fluid level at the end of the detection period (e.g., 299.70 mm). The degree of leakage is calculated using the formula: Magnetic Fluid Level Drop = Initial Height - Final Height. In the example above, the drop is 0.30 mm. The calculated magnetic fluid level drop is then compared with preset first and second leakage ranges to determine the leakage level.

[0068] The steps for handling minor leaks are as follows: Upon detecting a minor leak, the controller immediately triggers a magnetic fluid leakage warning. A local audible and visual alarm is activated, with a flashing red indicator light and a buzzer sounding once per second. Simultaneously, a remote alarm signal is sent to the converter station monitoring system, containing information such as the leak location and leakage value, prompting maintenance personnel for subsequent repairs. At the same time, a start command is sent to the dielectric pump 8 in the insulating liquid pipeline, opening the check valve and supplying insulating liquid to the magnetic fluid 6 pipeline. The insulating liquid is then injected into the filling medium plate 5 through the magnetic fluid 6 pipeline to fill the volume gap caused by the magnetic fluid leakage, maintaining the equivalent inductance of the filling medium plate 5 at a relatively stable level.

[0069] The controller first calculates the reduction comparison value using the formula: Reduction Comparison Value = Magnetic Fluid Reduction Value / Reduction Reference Value. In the example above, it is 0.30mm / 0.30mm = 1.0. Then, based on the positive correlation between the comparison value and the leak repair speed, the speed of the dielectric pump 8 is adjusted: If the reduction comparison value is 0.5 (minor leakage), the pumping speed of the insulating liquid is set to 0.2L / min; if the comparison value is 1.0 (moderate leakage), the speed is increased to 0.4L / min; if the comparison value is 1.5, which is close to the upper limit of the second leakage range, the speed is further increased to 0.6L / min to ensure that the leak repair speed matches the degree of leakage, thus avoiding inductance deviation due to insufficient liquid repair and preventing excessive pressure inside the filling dielectric plate 5 due to excessively fast liquid repair.

[0070] The steps for handling a large leak are as follows: Upon detecting a large leak, the controller immediately generates a second stop pumping command, sending a shutdown command to the dielectric pump 8 in the insulating liquid pipeline, closing the check valve, and terminating the insulating liquid repair process to prevent the insulating liquid from mixing with the large amount of leaked liquid and exacerbating equipment failure. Simultaneously, the magnetic fluid extraction process is initiated. The emergency extraction valve at the bottom of the filling medium plate 5 is opened. The emergency extraction valve is a large-diameter valve with a flow rate ≥20mm. The standby extraction pump (flow rate ≥1L / min) is started to quickly extract the remaining magnetic fluid 6 in the filling medium plate 5 to a dedicated recovery container, preventing the magnetic fluid from leaking into the sealed oil tank 3 and contaminating the insulating liquid. The liquid level is monitored in real time during the extraction process until it drops to the safe lower limit, such as 295.00mm, to ensure that no residual magnetic fluid blocks the pipeline.

[0071] After the magnetic fluid extraction is complete, the controller sends an "emergency shutdown prompt" to the converter station, suggesting that the filter be temporarily taken out of operation; at the same time, all valves of the filling medium plate 5 are closed, and the connection with other systems is cut off to prevent the subsequent fault from escalating. After the maintenance personnel arrive on site, they can quickly locate the leak point based on the leakage data (decrease value, detection time, extraction volume, etc.) stored in the controller, such as damaged gaskets or valve leakage, thus improving maintenance efficiency.

[0072] During the graded leakage treatment process, pressure and liquid level monitoring are required: real-time monitoring of the pressure inside the filling medium plate 5 can be achieved through a built-in pressure sensor, with a normal range of 0.1MPa-0.3MPa. If the pressure exceeds 0.3MPa during leak repair, the speed of the dielectric pump 8 should be immediately reduced; if the pressure is below 0.05MPa when extracting magnetic fluid, the pump should be stopped to avoid damage to the filling medium plate 5 due to negative pressure.

[0073] During the graded leakage handling process, it is necessary to isolate it from the main control function: during leakage handling, the magnetic liquid 6 control command is automatically blocked, and the leakage response action is executed first; if the capacitor control command is received at this time, it will only be executed when it is confirmed that there is no abnormality in the insulating liquid pipeline, so as to avoid the complexity of the fault caused by the linkage of multiple systems.

[0074] The above-mentioned graded treatment strategy allows for differentiated measures to be taken for different levels of leakage: for small leaks, dynamic leak repair is used to maintain equipment operation, while for large leaks, emergency pumping is used to protect the equipment. This ensures the safe operation of the high-voltage converter station filter and minimizes the impact of leakage on the power grid's power quality regulation.

[0075] This embodiment addresses the problem of abnormal insulation performance of the insulating liquid inside the sealed oil tank 3. The specific method also includes the following steps: Before activating the insulation performance grading function, basic parameter configuration and hardware system debugging must be completed to provide a basis for subsequent processing. The breakdown voltage (kV) of the insulating liquid is used as the core insulation parameter to reflect the insulation capacity. The normal operating value is ≥30kV, and two insulation levels are preset: First insulation range (slight reduction): 25kV-30kV, insulation performance deteriorates but can still operate for a short period of time, intervention is required; Second insulation range (severe damage): 20kV-25kV, insulation capacity is greatly reduced, there is a risk of breakdown, and emergency treatment is required; The second insulation range is completely contained within the first insulation range, and its upper limit (25kV) is lower than the normal critical value (30kV) of the first insulation range. At the same time, an insulation reference parameter of 30kV, i.e., the breakdown voltage value when the insulation performance is normal, is preset as the benchmark for calculating the insulation comparison value.

[0076] The rated volume parameters of the pre-set sealing oil tank 3, such as 500L, are determined based on the filter capacity design. The current volume parameters of the insulating liquid are detected in real time using a weighing sensor installed at the bottom of the tank or a liquid level-volume conversion sensor on the side wall. The closing valves of the filling medium plate 5 and the sealing oil tank 3 are adjusted to ensure complete disconnection from external pipelines upon receiving a closing command; the insulation parameter detection module is calibrated to ensure accurate data acquisition.

[0077] When the controller receives the second stop pumping command, usually triggered by a large magnetic fluid leak, the insulation system must be checked simultaneously, and the following operations should be initiated immediately: 1. Termination of insulating liquid transport: Send a stop command to dielectric pump 8 to terminate the extraction and pumping of insulating liquid, ensuring that the liquid in the pipeline is stationary and avoiding interference with insulation parameter detection due to flow.

[0078] 2. Dual-sealing control: A sealing command is sent to the electromagnetic shut-off valve of the liquid-filled medium plate 5 and the inlet and outlet valves of the sealing oil tank 3, completing the dual sealing within 1 second. The sealing of the liquid-filled medium plate 5 prevents residual magnetic fluid from seeping into the oil tank, while the sealing of the oil tank 3 prevents external air or impurities from entering, creating a stable environment for insulation parameter testing.

[0079] After sealing is completed, the controller starts insulation parameter detection: the probe of the control insulation parameter detection module is inserted into the insulating liquid in the sealed oil tank 3, the probe depth is ≥100mm, avoiding the sediment at the bottom of the oil tank, the breakdown voltage is detected 3 times in a row, and the average value is taken as the final insulation parameter. If the detection result is 27kV, it falls into the first insulation range.

[0080] After sealing is completed, the controller starts volume parameter detection: the current volume data of the insulating liquid is collected by the weighing sensor or liquid level sensor. If the current volume is 480L, which is lower than the rated 500L, there is a loss, which will be used as the basis for subsequent liquid replenishment or liquid replacement.

[0081] When the insulation parameters are within the first insulation range, such as 27kV, a slight reduction treatment is performed. The specific steps are as follows: Once the controller determines that the insulation performance has slightly deteriorated, it triggers an insulation performance degradation warning. A yellow audible and visual alarm is activated, the indicator light remains constantly on, and a buzzer sounds at a frequency of 0.5 times per second. A warning signal containing "insulation parameter value + current volume" is sent to the converter station monitoring system, prompting maintenance personnel to plan for maintenance.

[0082] The controller calculates the insulation comparison value using the formula: Insulation comparison value = Actual insulation parameter / Insulation reference parameter. In the example above, it is 27kV / 30kV = 0.9. Adjust the dielectric pump 8 according to the negative correlation between the comparison value and the replenishment rate: if the comparison value is 0.9, which is close to normal, set the replenishment rate to 0.5L / min and replenish slowly to avoid shock; if the comparison value is 0.8, which is significantly lower, increase the rate to 1L / min; if the comparison value is 0.7, which is close to the second range, increase the rate to 1.5L / min to ensure that the replenishment volume matches the degree of decrease in insulation performance. During the replenishment process, the volume parameters are monitored in real time. When the rated volume (500L) is reached, the pumping is automatically stopped and the valve of the insulating liquid pipeline is closed.

[0083] When the insulation parameters are within the second insulation range, such as 23kV, severe damage treatment should be performed. The specific steps are as follows: Once the controller determines that the insulation performance is severely damaged, it triggers an insulation performance failure warning. A red, urgent audible and visual alarm is activated, the indicator light flashes, and a buzzer sounds twice per second. An "emergency shutdown + insulation failure" signal is sent to the converter station, recommending that the filter be taken out of service immediately.

[0084] Initiate the old liquid draining process: Open the drain valve and dedicated liquid pump at the bottom of the sealed oil tank 3 to completely pump the insulating liquid in the oil tank to the dedicated recycling container to avoid environmental pollution, until the volume parameter is detected as 0L, with ±0.5L of residue allowed. Injecting new liquid: Based on the previously tested volume parameters, such as a rated volume of 500L, inject the same type of new insulating liquid (castor oil) into the sealed oil tank 3 through the insulating liquid pipeline. During the injection process, test the insulation parameters every 100L to ensure that the breakdown voltage of the new liquid is ≥30kV until the rated volume is reached, and then close the injection valve.

[0085] During the insulation performance grading process, the controller needs to monitor pressure and purity: monitor the pressure inside the sealed oil tank 3 in real time, with a normal range of 0.1-0.2MPa. If the pressure exceeds 0.2MPa when replenishing the liquid, reduce the pump speed; test the purity of the new liquid before injection, with a dielectric loss factor ≤0.005, to avoid secondary failure caused by inferior liquid.

[0086] During the insulation performance grading process, the controller needs to be isolated from other systems: during the process, the capacitor adjustment command is automatically blocked to prevent the flow of insulating liquid from interfering with the processing effect; if leakage is detected in the sealed oil tank 3, i.e., a sudden drop in pressure, the operation is immediately terminated and a special alarm for oil tank leakage is triggered.

[0087] During the insulation performance grading process, the controller needs to record and trace data: automatically store and process data throughout the entire process, including changes in insulation parameters, replenishment / replacement volume, operation time, etc., to form an insulation performance file, which makes it easy for maintenance personnel to trace the cause of failure, such as liquid aging, micro-leakage, etc.

[0088] The above-mentioned graded treatment strategy can accurately address different degrees of insulation performance degradation: when the degradation is slight, dynamic liquid replenishment can maintain operation; when the damage is severe, full liquid replacement can completely restore the insulation capacity. This not only ensures the insulation safety of the high-voltage converter station filter, but also minimizes equipment downtime and meets the stringent requirements of continuous operation of the converter station.

[0089] This application also discloses a control system for a composite LC filter in a high-voltage converter station, including a processor, wherein the processor executes the steps of the control method for the composite LC filter in a high-voltage converter station as described in any of the above embodiments.

[0090] This application also discloses a storage medium storing a program, which, when executed by a processor, implements the steps of the control method for the composite LC filter of the high-voltage converter station described in any of the above embodiments.

[0091] Although embodiments of this application have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting this application. Those skilled in the art can make changes, modifications, substitutions and variations to the above embodiments within the scope of this application.

Claims

1. A control method for a composite LC filter in a high-voltage converter station, characterized in that, The process includes the following steps: A hollow inductor, interlocking solid dielectric plates, and liquid-filled dielectric plates are installed inside a sealed oil tank, with the solid dielectric plates and liquid-filled dielectric plates arranged alternately; a second high-voltage terminal is connected to the solid dielectric plate, and the liquid-filled dielectric plate is connected in series with the hollow inductor and then connected to the first high-voltage terminal; a discharge resistor is connected in parallel between the liquid-filled dielectric plate and the solid dielectric plate, and a high-voltage fuse is connected in series between the solid dielectric plate and the second high-voltage terminal; a capacitor adjustment command is obtained, and the capacitor adjustment value is extracted from the capacitor adjustment command; insulating liquid is injected into or extracted from the sealed oil tank in response to the capacitor adjustment command, the volume and rate of change of the injected or extracted insulating liquid being positively correlated with the absolute value of the capacitor adjustment value; an inductance adjustment command is obtained, and the inductance adjustment value is extracted from the inductance adjustment command; magnetic fluid is injected into or extracted from the liquid-filled dielectric plate in response to the liquid injection command, the volume and rate of change of the injected or extracted magnetic fluid being positively correlated with the absolute value of the inductance adjustment value.

2. The control method for the composite LC filter in a high-voltage converter station according to claim 1, characterized in that, The method also includes the following steps: Obtain the insulating liquid level in the sealed oil tank (3); Calculate the first fluctuation range value of the insulating liquid level height within the set first calculation time; If the first fluctuation amplitude value is within the preset first liquid level fluctuation range, then while filling the sealing oil tank (3) with insulating liquid, the insulating liquid is extracted from the sealing oil tank (3), and the volume of the insulating liquid filled in is the same as the volume of the insulating liquid extracted. Obtain the height of the magnetic fluid level inside the fluid-filled medium plate (5); Calculate the second fluctuation amplitude value of the magnetic fluid surface height within the set second calculation time; If the second fluctuation amplitude value is within the preset second liquid level fluctuation range, then magnetic liquid (6) is injected into the filling medium plate (5) and magnetic liquid (6) is extracted from the filling medium plate (5) at the same time. The volume of the injected magnetic liquid (6) is the same as the volume of the extracted magnetic liquid (6).

3. The control method for the composite LC filter in a high-voltage converter station according to claim 2, characterized in that, The method also includes the following steps: Calculate the time interval between the most recent capacitor adjustment commands; calculate the capacitor adjustment frequency based on the multiple time intervals corresponding to the capacitor adjustment commands. The circulation speed of the insulating liquid being filled and extracted in the sealed oil tank (3) is adjusted according to the positive correlation between the capacitor adjustment frequency and the frequency. The higher the capacitor adjustment frequency, the faster the circulation speed of the insulating liquid; the lower the capacitor adjustment frequency, the slower the circulation speed of the insulating liquid. Calculate the time interval between the most recent multiple inductor adjustment commands; The inductor adjustment frequency is calculated based on multiple time intervals corresponding to the inductor adjustment command. The circulation speed of the magnetic fluid (6) being filled and extracted in the fluid-filled medium plate (5) is adjusted according to the positive correlation between the inductor adjustment frequency and the frequency. The higher the inductor adjustment frequency, the faster the circulation speed of the magnetic fluid (6), and the lower the inductor adjustment frequency, the slower the circulation speed of the magnetic fluid (6).

4. The control method for the composite LC filter in a high-voltage converter station according to claim 1, characterized in that, Using magnetic fluid (6) as the medium, the hollow part of the magnetic fluid storage unit (17) is connected to the hollow part inside the liquid filling medium plate (5) through the magnetic fluid pump (9) and the magnetic fluid pipeline valve (10); the magnetic fluid storage unit (17) and the hollow part inside the liquid filling medium plate (5) are connected through the magnetic fluid pipeline return pipe (12) to achieve air pressure balance; the liquid inlet is located at the low position of the magnetic fluid storage unit (17).

5. The control method for the composite LC filter in a high-voltage converter station according to claim 1, characterized in that, Using insulating liquid as the medium, the sealing oil tank (3) and the dielectric oil tank (7) are connected through the dielectric pump (8) and the dielectric pipeline valve (11), and the cavity of the sealing oil tank (3) and the dielectric oil tank (7) is connected through the dielectric pipeline return pipe (13) to balance the air pressure.

6. The control method for the composite LC filter in a high-voltage converter station according to claim 1, characterized in that, The method also includes the following steps: In response to the start command of the dielectric pump (8) or the magnetic fluid pump (9), the dielectric pump (8) and the magnetic fluid pump (9) are set to reverse linkage: when the dielectric pump (8) starts the pumping action, the magnetic fluid pump (9) starts the pumping action; when the dielectric pump (8) starts the pumping action, the magnetic fluid pump (9) starts the pumping action.

7. The control method for the composite LC filter in a high-voltage converter station according to claim 1, characterized in that, The method also includes the following steps: Upon receiving the first stop pumping command, in response to the first stop pumping command, stop pumping and pumping the magnetic fluid (6) and control the filling medium plate (5) to close. Calculate the magnetic fluid level drop within the set detection time. If the magnetic fluid reduction value is within the preset first leakage range, a magnetic fluid leakage warning is issued; the insulating fluid pipeline is connected to the magnetic fluid (6) pipeline through a one-way valve, and the insulating fluid is pumped into the filling medium plate (5) through the magnetic fluid (6) pipeline; the reduction comparison value is calculated based on the magnetic fluid reduction value and the preset reduction reference value, and the pumping speed of the insulating fluid is adjusted according to the positive correlation of the reduction comparison value. The larger the reduction comparison value, the faster the pumping speed of the insulating fluid, and the smaller the reduction comparison value, the slower the pumping speed of the insulating fluid. If the magnetic fluid drop value is within the preset second leakage range, a second stop pumping command is generated; the magnetic fluid (6) in the filling medium plate (5) is extracted; The second leakage range is located within the first leakage range, and the value within the second leakage range is greater than other values ​​within the first leakage range.

8. The control method for the composite LC filter in a high-voltage converter station according to claim 7, characterized in that, The method also includes the following steps: In response to the second stop pumping command, the pumping and extraction of insulating liquid is stopped, and the filling medium plate (5) and the sealing oil tank (3) are closed. The insulation parameters and volume parameters of the insulating liquid in the sealed oil tank (3) were tested; If the insulation parameters are within the preset first insulation range, a warning of reduced insulation performance will be issued; insulating liquid will be pumped into the sealing oil tank (3) through the insulating liquid pipeline; the insulation comparison value will be calculated based on the insulation parameters and the preset insulation reference parameters, and the pumping speed of the insulating liquid will be adjusted according to the negative correlation of the insulation comparison value. The larger the insulation comparison value, the slower the pumping speed of the insulating liquid, and the smaller the insulation comparison value, the faster the pumping speed of the insulating liquid. If the insulation parameters are within the preset second insulation range, an insulation performance damage warning will be issued; the insulating liquid in the sealing oil tank (3) will be emptied and discharged through the insulating liquid pipeline, and the insulating liquid corresponding to the volume parameters will be injected into the sealing oil tank (3); The second insulation range is located within the first insulation range, and the values ​​within the second insulation range are less than the other values ​​within the first insulation range.

9. A control system for a composite LC filter in a high-voltage converter station, characterized in that, The device includes a processor that performs the steps of the control method for the composite LC filter of a high-voltage converter station as described in any one of claims 1-8.

10. A storage medium, characterized in that, The storage medium stores a program that, when executed by a processor, implements the steps of the control method for the composite LC filter of the high-voltage converter station as described in any one of claims 1-8.

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