Overvoltage protection device for dry-type hollow shunt reactor

Abstract

The invention discloses an overvoltage protection device for a dry-type hollow shunt reactor, which belongs to the technical field of overvoltage protection of power transmission and transformation equipment, and is characterized in that when an operation overvoltage occurs in a system, a frequency absorption unit can reduce the oscillation frequency of the overvoltage, slow down the rising leading edge of the overvoltage, and solve the damage of a high-frequency component to a reactor winding; when the frequency absorption unit cannot restrain the overvoltage peak value, the overvoltage absorption unit plays a role in limiting the overvoltage peak value and enhancing the insulation level of the reactor, and through the application of the voltage monitoring conversion unit, when the reactor operates normally or the overvoltage is lower than an operation threshold value, the high-speed control switch is switched on, and the high-speed control switch is switched off. The explosion-proof separation unit is bypassed by a short circuit, and the frequency suppression absorption unit and the overvoltage absorption unit undertake the main protection task; when the monitored voltage exceeds a set threshold value or the absorption unit has a fault or thermal breakdown, the high-speed control switch is switched off, the explosion-proof separation unit is connected to the circuit, the fault unit is timely cut off, and fault extension is prevented.

Description

Technical Field

[0001] This invention belongs to the field of overvoltage protection technology for power transmission and transformation equipment, specifically an overvoltage protection device for dry-type air-core parallel reactors. Background Technology

[0002] With the development of my country's power industry, long-distance, large-capacity high-voltage AC / DC transmission networks have gradually taken shape, placing higher demands on the performance of related power equipment. Dry-type air-core reactors, due to their simple structure, stable inductance, and convenient maintenance, are widely used in various power transmission and transformation projects and play a crucial role. As an important coreless device, dry-type air-core reactors are widely used in parallel, series, and smoothing applications due to their simple structure, oil-free operation, and good linear inductance characteristics. They effectively suppress voltage rise at the terminals, limit short-circuit current, filter out DC pulsating voltage, and ensure the safe operation of the power system.

[0003] Circuit breakers are widely used in power systems due to their excellent arc-extinguishing performance. However, frequent switching of reactive power compensation devices such as reactors can easily generate high-amplitude, high-frequency operational overvoltages, leading to accidents such as switchgear explosions and insulation breakdowns. In particular, they can damage the inter-turn insulation of reactors, becoming a significant factor in causing faults. During reactor switching, common current-cutting overvoltages and reignition overvoltages further exacerbate the risk of insulation damage, posing a serious threat to the stable operation of the power system.

[0004] In recent years, various methods have been proposed to suppress switching overvoltages caused by circuit breakers, including improving the circuit breaker itself and adding external protection devices. Improving contact materials can reduce the circuit breaker's current-carrying capacity. Phase control technology, surge arresters, parallel capacitors, and resistor-capacitor suppression devices are also used. Surge arresters can effectively reduce overvoltage peak values, but have little impact on the steepness of high-frequency surges. RC absorbers can suppress high-frequency oscillations through resistive energy dissipation, but their capacitive elements are susceptible to performance fluctuations due to electrical stress and temperature during long-term operation. Therefore, to effectively address the hazards of switching overvoltages to parallel reactors, this invention proposes an overvoltage protection device for dry-type air-core parallel reactors, including a voltage monitoring unit and a fault isolation device. Summary of the Invention

[0005] The technical solution of this invention is as follows: an overvoltage protection device for a dry-type air-core parallel reactor, comprising: The device, consisting of a mounting bracket, frequency suppression absorption unit, overvoltage absorption unit, explosion-proof disconnection unit, and voltage monitoring and conversion unit, is connected in parallel with a dry-type air-core parallel reactor. The frequency suppression absorption unit, composed of an RC network, is used to absorb high-frequency transient overvoltages during reactor switching operations, suppress oscillation components, and reduce electromagnetic interference. The overvoltage absorption unit is a metal oxide surge arrester element that conducts when the operating voltage exceeds a set threshold, clamping the overvoltage amplitude and discharging the energy to ground. The explosion-proof disconnection unit is used to disconnect the faulty unit when the overvoltage absorption unit or frequency suppression absorption unit breaks down or overheats abnormally, achieving electrical and mechanical separation. The voltage monitoring and conversion unit consists of a high-precision voltage sensor, a digital signal processor, and a high-speed control switch. Based on preset thresholds and logical judgments, it outputs control signals to the control switch. The voltage monitoring unit is connected in parallel with the explosion-proof disconnection unit. By comparing the monitored voltage with the preset threshold and applying logical judgments, it outputs control signals to the high-speed control switch.

[0006] When the high-precision voltage sensor detects that the reactor is at the normal operating voltage or the voltage rises but does not reach the operating overvoltage threshold, the high-speed control switch is in the conducting state, which short-circuits the explosion-proof disconnection unit. At this time, the frequency suppression absorption unit and the overvoltage absorption unit play the main protective role to suppress transient voltage fluctuations. When the high-precision voltage sensor detects an overvoltage exceeding the set threshold, the digital signal processor sends a control signal to disconnect the high-speed control switch, and the explosion-proof disconnect unit is connected to the circuit. At this time, the explosion-proof disconnect unit is in working condition and plays a role in suppressing and protecting against voltage spikes or abnormal voltages. The explosion-proof mechanism and fuse inside the explosion-proof disconnect unit immediately disconnect the faulty unit, achieving electrical and mechanical isolation. When the high-precision voltage sensor detects a significant drop in voltage below the set lower limit, or when the monitored value approaches 0, it is determined that the frequency suppression absorption unit or overvoltage absorption unit has malfunctioned, thermally broken down, or failed. At this time, the high-speed control switch is also switched to the open state, and the explosion-proof disconnection unit is in working state. The faulty unit is disconnected through the internal explosion-proof mechanism and fuse device, which effectively avoids arc propagation and secondary damage to the equipment, and further improves the overall reliability and safety of the reactor.

[0007] Furthermore, the mounting brackets are used to support and secure the various functional units of the entire overvoltage protection device.

[0008] Furthermore, the entire device is connected in parallel with a dry-type air-core parallel reactor via a device connection busbar.

[0009] Furthermore, it also includes a counter and a counter mounting bracket. The counter is connected in parallel with a dry-type air-core shunt reactor and is used to record the number of times the overvoltage absorption unit operates. The counter mounting bracket is used to fix the counter.

[0010] Furthermore, the explosion-proof disconnect unit is equipped with an explosion-proof mechanism and a fuse. The explosion-proof mechanism is responsible for bearing or guiding the release of internal pressure or gas when a fault occurs, preventing the casing from cracking or sparks from flying. When the fuse detects abnormal current, excessive temperature, or breakdown, it melts the switch component to cut off the faulty electrical connection.

[0011] The beneficial effects of this invention are as follows: This invention provides a highly reliable overvoltage protection device for dry-type air-core parallel reactors. During reactor switching, the device can monitor operational overvoltages in real time. Through a voltage monitoring conversion unit, it enables the activation and deactivation of the explosion-proof disconnection unit. It weakens high-frequency oscillations through a frequency suppression absorption unit, clamps the overvoltage amplitude through an overvoltage absorption unit, and achieves safe disconnection in the event of a device failure with the help of the explosion-proof disconnection unit. This effectively eliminates the threat of overvoltage to the reactor insulation system and ensures the reliable operation of the dry-type air-core parallel reactor and the system. Attached Figure Description

[0012] Figure 1 This is a schematic diagram of the structure of the present invention; Figure 2 This is a circuit diagram of the present invention; In the picture: 1. Mounting bracket, 2. Explosion-proof disconnection unit, 3. Voltage monitoring and conversion unit, 4. Frequency suppression and absorption unit, 5. Overvoltage absorption unit, 6. Device connection bar, 7. Counter, 8. Counter mounting bracket, 9. Resistor, 10. Reactor. Detailed Implementation

[0013] It should be noted that in the description of this invention, the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer", "clockwise", "counterclockwise", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation.

[0014] In this invention, unless otherwise explicitly specified and limited, the terms "set," "install," "connect," and "link," etc., should be interpreted broadly. For example, "fixed" can mean a fixed connection, a detachable connection, or an integral part; a connection can be a mechanical connection or an electrical connection; a link can be a direct connection or an indirect connection through an intermediate medium, and can refer to the internal communication of two components or the interaction between two components. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0015] See Figure 1 The explosion-proof disconnection unit 2 and the voltage monitoring and conversion unit 4 are connected to the top of the reactor 10 through the mounting bracket 1. The explosion-proof disconnection unit 2 and the voltage monitoring and conversion unit 3 are connected in parallel. The frequency suppression absorption unit 4 and the overvoltage absorption unit 5 are connected in parallel. They are connected to the bottom of the explosion-proof disconnection unit 2 and the voltage monitoring and conversion unit 3 through the device connection bar 6. The bottom of the frequency suppression absorption unit 4 and the overvoltage absorption unit 5 are connected to the counter 7, and are connected to the bottom of the reactor 10 through the counter mounting bracket 8.

[0016] The circuit connection diagram of explosion-proof disconnection unit 2, voltage monitoring and conversion unit 3, frequency suppression absorption unit 4, and overvoltage absorption unit 5 is shown below. Figure 2 As shown.

[0017] Mounting bracket 1 is used to support and fix the various functional units of the entire overvoltage protection device. It is preferably made of stainless steel or composite insulating material. Its thickness is 4-8 mm, and the surface is treated with hot-dip galvanizing or spray coating for corrosion protection, with a corrosion resistance life of more than 15 years. The overall load-bearing capacity is not less than 200 kg, which can ensure the long-term stable operation of the device in outdoor environments.

[0018] The explosion-proof disconnection unit 2 includes a fuse and an explosion-proof mechanism. The fuse current range is 50–200 A, and the action time is less than 5 ms. The mechanical separation gap is not less than 20 mm, and it has an explosion-proof pressure relief channel, which can quickly cut off the fault and ensure the safety of the device casing when the component breaks down.

[0019] The voltage monitoring and conversion unit 3 is used to monitor the terminal voltage of the dry-type air-core parallel reactor in real time, and controls the connection or bypass status of the explosion-proof disconnection unit 2 according to the monitoring results, so as to realize dynamic protection against overvoltage. The voltage monitoring and conversion unit 3 includes: a high-precision voltage sensor, a voltage monitoring device, a digital signal processor, and a high-speed control switch.

[0020] A high-precision voltage sensor converts the high-voltage signal at reactor terminal 10 into a low-voltage signal suitable for digital processing. The voltage monitoring device samples, filters, and amplifies the sensor signal to ensure accurate voltage amplitude reflection even under high-frequency oscillations and transient overvoltage conditions. The digital signal processor compares the acquired voltage signal with a preset threshold and outputs control commands based on logical judgment. Two trigger thresholds can be preset according to actual system parameters to achieve graded protection. A high-speed control switch receives DSP control signals to enable rapid access or bypass operation of the explosion-proof disconnect unit, with an action time of less than 1 ms, ensuring timely response in the event of a sudden overvoltage. When the voltage monitoring and conversion unit 3 detects no operational overvoltage, the high-speed control switch can return to its original state.

[0021] The two-level trigger thresholds include a low threshold U1 and a high threshold U2. U1 is 0.2 times the initial monitoring voltage of the voltage monitoring conversion unit during normal operation, and U2 is 1.3-1.5 times the initial monitoring voltage of the voltage monitoring conversion unit during normal operation. When the voltage value monitored by the voltage monitoring conversion unit 3 is lower than U1, it indicates that the frequency suppression absorption unit 4 or the overvoltage absorption unit 5 has failed, resulting in a decrease in the monitoring voltage. At this time, the high-speed control switch is disconnected, and the explosion-proof disconnection unit 2 is engaged in the protection circuit. If the frequency suppression absorption unit 4 or the overvoltage absorption unit 5 breaks down, overheats abnormally, or fails, the explosion-proof mechanism and fuse inside the explosion-proof disconnection unit 2 can immediately disconnect the faulty unit, achieving reliable electrical and mechanical isolation, thereby preventing the fault from spreading and ensuring the safety of the reactor 10. When the voltage value monitored by the voltage monitoring conversion unit 3 is greater than U1 and less than U2, the high-speed control switch is closed, causing the explosion-proof disconnection unit 2 to be short-circuited and bypassed, that is, the explosion-proof disconnection unit 2 does not participate in the circuit temporarily. At this time, the frequency suppression absorption unit 4 and the overvoltage absorption unit 5 play the main protective role in suppressing small-amplitude transient voltage fluctuations; when the voltage monitoring and conversion unit 3 monitors a voltage value greater than U2, the high-speed control switch is disconnected, and the explosion-proof disconnection unit 2 is connected to the circuit to play the role of suppressing and protecting against voltage spikes or abnormal voltages.

[0022] The frequency suppression absorption unit 4 is composed of a resistive-capacitive network and is used to absorb high-frequency transient components during the switching operation of reactor 10, suppress oscillating voltage, reduce the rise steepness of overvoltage, and mitigate the electrical stress impact of high-frequency shocks on reactor insulation and surrounding equipment. In the frequency suppression absorption unit 4, the resistive elements are metal film resistors or alloy wire-wound resistors, which have good impact resistance and temperature stability, with resistance values ​​ranging from 50 to 500Ω. The capacitive elements are high-voltage parallel capacitors with unit capacitance ranging from 0.05 to 0.5μF. The rated voltage level can be configured according to the system voltage level and is suitable for 35 kV to 220 kV reactor systems.

[0023] Overvoltage absorption unit 5 is a metal oxide surge arrester (MOA) used to rapidly conduct when switching overvoltages or power frequency transient overvoltages occur. Through its nonlinear volt-ampere characteristics, it clamps the overvoltage amplitude and dissipates energy, thereby protecting the reactor winding insulation. Its rated voltage can be selected according to the specific application, suitable for medium-voltage or high-voltage reactors, meeting the requirements of 35kV~220kV systems. This unit has a residual voltage ratio of no more than 2.0, a current carrying capacity of no less than 2000A (8 / 20μs impulse current), and an energy absorption capacity greater than 3kJ / kV, effectively limiting power frequency transient overvoltages and switching overvoltages.

[0024] The device connection pin 6 is made of T2 copper or aluminum alloy with a conductivity ≥ 98% IACS. The typical cross-sectional area is 50–150 mm², and the allowable current is not less than 500 A. The surface is treated with tin plating or an anti-corrosion coating to ensure long-term reliable conductivity.

[0025] Counter 7 is an electromagnetic or electronic action counter, with a rated voltage level matching that of the overvoltage absorption unit 5. The action counting range is 0 to 99,999 times, with a display accuracy of ±1 count, and it can operate reliably for extended periods in environments ranging from -40℃ to +60℃.

[0026] The counter mounting bracket 8 is made of stainless steel plate or composite insulating plate with a thickness of 3-6 mm and a surface coated with an anti-corrosion coating. Its mechanical strength can withstand a torque of 20 N·m, and it is not easily deformed, ensuring stable operation of the counter under harsh outdoor conditions.

[0027] In this embodiment, by setting two-level trigger thresholds in the voltage monitoring and conversion unit, the unit can achieve graded and staged protection for the dry-type air-core parallel reactor. When a slight overvoltage occurs, only the frequency suppression absorption unit and the overvoltage absorption unit are activated to reduce system energy loss. When a severe overvoltage occurs, the explosion-proof disconnection unit is quickly activated to enhance the protection level. When the absorption unit fails, the system can automatically disconnect the abnormal branch to prevent thermal collapse or short circuit propagation. This device not only significantly improves the response speed and protection accuracy of the device, but also extends the service life and reliability of the explosion-proof disconnection unit through the graded switching mechanism, thereby improving the safety and reliability of the entire dry-type air-core parallel reactor system.

[0028] In this embodiment, the overvoltage absorption unit operates at high resistance under normal operating voltage, with minimal current flow and insensitivity to voltage changes, essentially functioning as an insulator. When subjected to a high-amplitude overvoltage surge, its conductivity rapidly increases and its resistance drastically decreases, exhibiting characteristics approaching a short circuit. This short-circuit state is reversible; once the overvoltage dissipates, the overvoltage absorption unit returns to its high-resistance state. Therefore, by configuring zinc oxide surge arresters in power equipment, in the event of an overvoltage, the varistor conducts, diverting current to the ground, thereby limiting the voltage across the equipment to a safe level and effectively protecting the insulation and operational safety of the electrical equipment.

[0029] In this embodiment, the frequency suppression absorption unit can significantly reduce the amplitude of the current-cutting overvoltage and slow down its oscillation process. As the capacitance of the parallel capacitor increases, both the overvoltage amplitude and the oscillation frequency show a decreasing trend. At the same time, the resistive element in the RC absorption circuit plays a damping role, which can consume part of the energy in the oscillation circuit, thereby achieving an effective suppression effect. During normal operation, the fault separation unit is not activated. When the voltage monitoring and conversion unit detects a high operating overvoltage, the fault separation unit is activated. When the overvoltage absorption unit experiences a permanent thermal breakdown fault, the fault separation unit quickly acts to separate the permanently thermally broken-down faulty unit from the system, avoiding a system short circuit accident. Each discrete unit is small in size, easy to operate, and simple to install, making future maintenance and repair more convenient and faster.

[0030] The above description is merely a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any modifications, equivalent substitutions, and improvements made by those skilled in the art within the scope of the technology disclosed in the present invention, and within the spirit and principles of the present invention, should be included within the scope of protection of the present invention. Furthermore, all content not described in detail in this specification is prior art known to those skilled in the art.

[0031] It should be noted that, in this document, relational terms such as "first" and "second" are used only to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such process, method, article, or apparatus.

Claims

1. An overvoltage protection device for a dry-type air-core parallel reactor, characterized in that, include: The device consists of a mounting bracket, a frequency suppression absorption unit, an overvoltage absorption unit, an explosion-proof disconnection unit, and a voltage monitoring and conversion unit. The entire device is connected in parallel with a dry-type air-core parallel reactor. The frequency suppression absorption unit is composed of an RC network and is used to absorb high-frequency transient overvoltages during reactor switching operations, suppress oscillation components, and reduce electromagnetic interference. The overvoltage absorption unit is a metal oxide surge arrester element that conducts when the operating voltage exceeds a set threshold, clamping the overvoltage amplitude and discharging the energy to ground. The explosion-proof disconnection unit is used to disconnect the faulty unit when the overvoltage absorption unit or the frequency suppression absorption unit breaks down or overheats abnormally, achieving electrical and mechanical separation. The voltage monitoring and conversion unit consists of a high-precision voltage sensor, a digital signal processor, and a high-speed control switch. Based on a preset threshold and logical judgment, it outputs a control signal to the control switch. The voltage monitoring unit is connected in parallel with the explosion-proof disconnection unit. By comparing the monitored voltage with a preset threshold and applying logical judgment, it outputs a control signal to the high-speed control switch. When the high-precision voltage sensor detects that the reactor is at the normal operating voltage or the voltage rises but does not reach the operating overvoltage threshold, the high-speed control switch is in the conducting state, which short-circuits the explosion-proof disconnection unit. At this time, the frequency suppression absorption unit and the overvoltage absorption unit play the main protective role to suppress transient voltage fluctuations. When the high-precision voltage sensor detects an overvoltage exceeding the set threshold, the digital signal processor sends a control signal to disconnect the high-speed control switch, and the explosion-proof disconnect unit is connected to the circuit. At this time, the explosion-proof disconnect unit is in working condition and plays a role in suppressing and protecting against voltage spikes or abnormal voltages. The explosion-proof mechanism and fuse inside the explosion-proof disconnect unit immediately disconnect the faulty unit, achieving electrical and mechanical isolation. When the high-precision voltage sensor detects a significant drop in voltage below the set lower limit, or when the monitored value approaches 0, it is determined that the frequency suppression absorption unit or overvoltage absorption unit has malfunctioned, thermally broken down, or failed. At this time, the high-speed control switch is also switched to the open state, and the explosion-proof disconnection unit is in working state. The faulty unit is disconnected through the internal explosion-proof mechanism and fuse device.

2. The overvoltage protection device for a dry-type air-core parallel reactor according to claim 1, characterized in that, Mounting brackets are used to support and secure the various functional units of the entire overvoltage protection device.

3. The overvoltage protection device for a dry-type air-core parallel reactor according to claim 1, characterized in that, The entire device is connected in parallel with a dry-type air-core parallel reactor via a device connection bar.

4. The overvoltage protection device for a dry-type air-core parallel reactor according to claim 1, characterized in that, It also includes a counter and a counter mounting bracket. The counter is connected in parallel with a dry-type air-core shunt reactor and is used to record the number of times the overvoltage absorption unit operates. The counter mounting bracket is used to fix the counter.

5. The overvoltage protection device for a dry-type air-core parallel reactor according to claim 1, characterized in that, The explosion-proof disconnect unit is equipped with an explosion-proof mechanism and a fuse. The explosion-proof mechanism is responsible for bearing or guiding the release of internal pressure or gas in the event of a fault, preventing the casing from cracking or sparks from flying. The fuse will blow the switch component and cut off the faulty electrical connection when it detects abnormal current, excessive temperature or breakdown.

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