High-voltage TSC reactive power compensation device based on zero-cross detection circuit

Abstract

The invention relates to the technical field of circuit protection devices, in particular to a high-voltage TSC reactive power compensation device based on a zero-cross detection circuit. The technical problem is that in the working process of a high-voltage TSC reactive power compensation device in the prior art, due to large zero-cross detection error and breakdown detection lag, silicon controlled rectifier overvoltage damage and whole set breakdown are caused. According to the technical scheme, the high-voltage TSC reactive power compensation device based on the zero-cross detection circuit comprises an electrical cabinet, and a valve group, a symmetrical divider resistance module, a zero-cross detection control unit, an optical fiber communication interface and an energy-taking power supply module are integrated in the electrical cabinet; by optimizing the zero-crossing detection precision and increasing the voltage symmetry verification and redundancy protection mechanism, the problems of silicon controlled rectifier overvoltage damage and whole group breakdown caused by large zero-crossing detection error and breakdown detection lag in the prior art are solved, so that the accident risk is reduced, and the economic loss of secondary faults is reduced.

Description

Technical Field

[0001] This invention relates to the field of circuit protection device technology, and in particular to a high-voltage TSC reactive power compensation device based on a zero-crossing detection circuit. Background Technology

[0002] High-voltage TSC (thyristor switched capacitor) reactive power compensation devices are key equipment in power systems used to dynamically adjust reactive power and improve the power factor of the power grid. Its core component is a high-voltage valve group, which is usually composed of dozens or even hundreds of high-voltage thyristors (SCRs) connected in series. Reactive power compensation is achieved by rapidly switching capacitor banks. In the existing technology, the zero-crossing detection circuit of the high-voltage TSC device is the core component to ensure the safe switching of thyristors. Its function is to trigger the thyristor to conduct near the zero-crossing point of the system voltage, so as to minimize the inrush current (surge current) during switching and protect the thyristor and related equipment.

[0003] However, the zero-crossing detection circuit and protection mechanism of existing high-voltage TSC reactive power compensation devices have significant defects. First, traditional zero-crossing detection circuits mostly use single-ended voltage sampling or simple voltage divider structures, resulting in low detection accuracy and large errors in zero-crossing point judgment. This can lead to a large inrush current when the thyristor is switched on or off, which will accelerate the aging or even damage of the thyristor in the long run. Second, the valve group redundancy design of existing devices (such as 32 thyristors in series with 2-3 redundant ones) can cope with a small number of thyristor failures, but it lacks an effective breakdown detection and redundancy protection mechanism. When multiple thyristors break down due to overvoltage, overcurrent, etc., the remaining thyristors need to bear higher voltages. However, traditional detection circuits cannot monitor the symmetry of the valve group voltage distribution in real time and cannot lock the valve group in time before the redundancy is exhausted (such as when the third thyristor breaks down). This causes the remaining thyristors to be continuously damaged due to overvoltage, eventually leading to a breakdown accident of the entire group, causing equipment downtime and additional economic losses.

[0004] To address the aforementioned problems, this invention provides a high-voltage TSC reactive power compensation device based on a zero-crossing detection circuit. By optimizing the zero-crossing detection accuracy, adding voltage symmetry verification and redundant protection mechanisms, it solves the problems of thyristor overvoltage damage and overall breakdown caused by large zero-crossing detection errors and delayed breakdown detection in the prior art, thereby reducing accident risks and minimizing economic losses from secondary faults. Summary of the Invention

[0005] In order to overcome the problems of thyristor overvoltage damage and overall breakdown caused by large zero-crossing detection error and delayed breakdown detection in the operation of high-voltage TSC reactive power compensation devices under existing technology in daily use.

[0006] The technical solution of the present invention is: a high-voltage TSC reactive power compensation device based on a zero-crossing detection circuit, comprising an electrical cabinet, wherein the electrical cabinet integrates a valve group, a symmetrical voltage divider resistor module, a zero-crossing detection control unit, an optical fiber communication interface, and an energy harvesting and power supply module. The valve group is a high-voltage switching unit composed of multiple thyristors connected in series; the high-voltage input terminal of the symmetrical voltage divider resistor module is connected to the starting terminal of the valve group, the low-voltage output terminal is connected to the center point of the valve group, and the reference terminal is connected to the end of the valve group; the voltage sampling terminal of the zero-crossing detection control unit is electrically connected to the output terminal of the symmetrical voltage divider resistor module; the optical fiber communication interface is bidirectionally connected to the data port of the zero-crossing detection control unit via optical signals; the input terminal of the power supply module is connected to the high-frequency current power supply terminal of the valve group, and the output terminal supplies power to the zero-crossing detection control unit; the command input terminal of the zero-crossing detection control unit is connected to the switching command port of the valve group.

[0007] The valve assembly is connected in series with an SCR. The zero-crossing detection circuit monitors the voltage relationship between the start, center, and end points of the valve assembly to achieve the following: SCR is protected by reducing inrush current through precise zero-crossing switching; Voltage symmetry verification is used to predict SCR breakdown faults; Redundancy exhaustion protection is used to prevent the entire group from breaking down. Preferably, the valve group consists of 32 high-voltage thyristors connected in series, physically divided into two sub-units of 16 thyristors each, forming three key nodes: the starting end, the center point, and the ending point. This provides the physical basis for symmetrical voltage sampling. The center point directly reflects the health status of the valve group. The symmetrical voltage divider resistor module uses two resistors with equal resistance values ​​to proportionally attenuate the system phase voltage to a low-voltage measurable range. The zero-crossing detection control unit performs RC filtering on the voltage of each terminal, calculates and outputs the zero-crossing pulse in real time, and uses a logic processor to verify voltage symmetry and perform redundant protection, thereby reducing zero-crossing detection errors and achieving rapid blocking under breakdown faults. This device reduces zero-crossing errors through a symmetrical voltage divider network and a high-speed comparator, thereby reducing inrush current and extending the life of the thyristors. Through a redundant protection mechanism based on voltage symmetry criteria, it can block the valve in advance when the third thyristor breaks down, reducing the overall breakdown accident rate, thereby reducing the risk of accidents and economic losses caused by secondary faults, improving the accuracy of the zero-crossing trigger detection circuit, reducing inrush current, and protecting the thyristors.

[0008] Preferably, the symmetrical voltage divider resistor module includes a first high-voltage resistor and a second high-voltage resistor. The first end of the first high-voltage resistor is connected to the starting end of the valve group, the second end of the high-voltage resistor is connected to the center point of the valve group, the first end of the second high-voltage resistor is connected to the center point of the valve group, and the second end of the second high-voltage resistor is connected to the end of the valve group. The resistance values ​​of the first high-voltage resistor and the second high-voltage resistor are equal, and the resistance value range is 1MΩ-10MΩ.

[0009] Preferably, the center point of the valve group is the physical dividing point of multiple series-connected thyristors, dividing the valve group into two sub-units with the same number of thyristors.

[0010] Preferably, the zero-crossing detection control unit includes: The signal conditioning circuit performs RC filtering and proportional attenuation on the voltage at the start, center, and end of the valve group; A high-speed differential comparator is used to calculate the valve group voltage in real time and output a zero-crossing pulse signal; The logic processor verifies the voltage symmetry based on the voltage at the center point of the valve group. When the difference between the voltage at the center point of the valve group and the voltage at the beginning and end of the valve group and the average value exceeds a certain threshold, a fault flag is generated.

[0011] The valve group voltage is calculated using the following formula: ; The voltage symmetry is verified based on the voltage at the center point of the valve group, specifically as follows: .

[0012] Preferably, the high-speed differential comparator uses an isolated comparator chip with a response time of ≤50ns.

[0013] Preferably, the optical fiber communication interface integrates an SFP optical module to support full-duplex communication, and exchanges zero-crossing time and fault status data with the valve group through the valve group's optical fiber input port.

[0014] Preferably, the power supply module includes: A high-frequency current transformer is used to sense the high-frequency current at the high-frequency current harvesting terminal of the valve group. The rectifier and voltage regulator circuit is used to convert the induced current into a 3.3V / 5V DC power supply.

[0015] Preferably, the logic processor integrates a redundancy protection mechanism, and the logic processor is configured as follows: When three consecutive cycles of voltage asymmetry are detected, a valve group lockout command is sent through the fiber optic communication interface. The remaining voltage that the thyristor can withstand is calculated in real time. If it exceeds 115% of the rated voltage, an emergency shutdown is triggered.

[0016] The zero-crossing detection method based on the above-mentioned high-voltage TSC reactive power compensation device includes the following steps: S1: Real-time acquisition of voltage signals at the valve group start end, valve group center point and valve group end through symmetrical voltage divider resistor module; S2: Based on the voltage signal, the zero-crossing detection control unit calculates the voltage across the valve group in real time using differential calculation and detects its zero-crossing point; S3: The zero-crossing detection result is fed back to the valve group through the fiber optic communication port; S4: Receives the switching command sent by the valve group through the switching command port; S5: Triggering the switching of the thyristor valve group at the zero crossing point.

[0017] Preferably, the triggering control of step S5 includes: The switching will only be performed if the following conditions are met simultaneously: A valid zero-crossing point was detected. b receives the valve assembly's start / stop command; Valve group C has no fault indication.

[0018] The beneficial effects of this invention are: This device reduces zero-crossing error through a symmetrical voltage divider network and a high-speed comparator, thereby reducing inrush current and extending the life of the thyristor. Through a redundant protection mechanism based on voltage symmetry criteria, it can lock out the thyristor in advance when the third thyristor breaks down, reducing the overall breakdown failure rate, thus reducing the risk of accidents and economic losses caused by secondary faults, improving the accuracy of the zero-crossing trigger detection circuit and reducing inrush current, and protecting the thyristors. Attached Figure Description

[0019] Figure 1 The diagram shown is a three-dimensional structural schematic of the high-voltage TSC reactive power compensation device based on a zero-crossing detection circuit according to the present invention. Figure 2 The diagram shown illustrates the working process of the high-voltage TSC reactive power compensation device based on a zero-crossing detection circuit according to the present invention. Figure 3 The diagram shown is a schematic diagram of the valve group terminal wiring of the high-voltage TSC reactive power compensation device based on the zero-crossing detection circuit of the present invention. Figure 4 The diagram shown is a schematic diagram of the circuit principle of the high-voltage TSC reactive power compensation device based on the zero-crossing detection circuit of the present invention. Explanation of reference numerals in the attached diagram: 1. Start end; 2. Center point; 3. End point; 4. Fiber optic input port; 5. Switching command port; 6. High-frequency current power extraction end; 7. Electrical cabinet. Detailed Implementation

[0020] The present invention will be further described below with reference to the accompanying drawings and embodiments.

[0021] Please see Figure 1 , Figure 2 , Figure 3 and Figure 4A high-voltage TSC reactive power compensation device based on a zero-crossing detection circuit includes an electrical cabinet 7, which integrates a valve group, a symmetrical voltage divider resistor module, a zero-crossing detection control unit, an optical fiber communication interface, and an energy harvesting and power supply module. The valve group is a high-voltage switching unit composed of multiple thyristors connected in series; the high-voltage input terminal of the symmetrical voltage divider resistor module is connected to the starting terminal 1 of the valve group, the low-voltage output terminal is connected to the center point 2 of the valve group, and the reference terminal is connected to the end terminal 3 of the valve group; the voltage sampling terminal of the zero-crossing detection control unit is electrically connected to the output terminal of the symmetrical voltage divider resistor module; the optical fiber communication interface is bidirectionally connected to the data port of the zero-crossing detection control unit via optical signals; the input terminal of the power supply module is connected to the high-frequency current power supply terminal 6 of the valve group, and the output terminal supplies power to the zero-crossing detection control unit; the command input terminal of the zero-crossing detection control unit is connected to the switching command port 5 of the valve group.

[0022] The valve assembly is connected in series with an SCR. The zero-crossing detection circuit monitors the voltage relationship between the valve assembly's starting point 1, center point 2, and ending point 3 to achieve the following: SCR is protected by reducing inrush current through precise zero-crossing switching; Voltage symmetry verification is used to predict SCR breakdown faults; Redundancy exhaustion protection is used to prevent the entire group from breaking down. The valve group consists of 32 high-voltage thyristors connected in series, physically divided into two sub-units of 16 thyristors each, forming three key nodes: starting point 1, center point 2, and ending point 3. This provides the physical basis for symmetrical voltage sampling. Center point 2 directly reflects the health status of the valve group. The symmetrical voltage divider resistor module uses two resistors with equal resistance to proportionally attenuate the system phase voltage to a low-voltage measurable range. The zero-crossing detection control unit performs RC filtering on the voltage of each terminal, calculates and outputs the zero-crossing pulse in real time, and uses a logic processor to verify voltage symmetry and perform redundant protection, thereby reducing zero-crossing detection errors and achieving rapid blocking under breakdown faults. This device reduces zero-crossing errors through a symmetrical voltage divider network and a high-speed comparator, thereby reducing inrush current and extending the life of the thyristors. Through a redundant protection mechanism based on voltage symmetry criteria, it can block the valve in advance when the third thyristor breaks down, reducing the overall breakdown accident rate, thereby reducing the risk of accidents and economic losses caused by secondary faults, improving the accuracy of the zero-crossing trigger detection circuit, reducing inrush current, and protecting the thyristors.

[0023] The symmetrical voltage divider resistor module includes a first high-voltage resistor and a second high-voltage resistor. The first end of the first high-voltage resistor is connected to the starting end 1 of the valve group, the second end of the high-voltage resistor is connected to the center point 2 of the valve group, the first end of the second high-voltage resistor is connected to the center point 2 of the valve group, and the second end of the second high-voltage resistor is connected to the end point 3 of the valve group. The resistance values ​​of the first high-voltage resistor and the second high-voltage resistor are equal, and the resistance value range is 1MΩ-10MΩ.

[0024] The valve group center point 2 is a physical dividing point for multiple series-connected thyristors, dividing the valve group into two sub-units with the same number of thyristors.

[0025] The zero-crossing detection control unit includes: The signal conditioning circuit performs RC filtering and proportional attenuation on the voltage at the starting end 1, center point 2 and end point 3 of the valve group; A high-speed differential comparator is used to calculate the valve group voltage in real time and output a zero-crossing pulse signal; The logic processor verifies the voltage symmetry based on the voltage at the center point 2 of the valve group. When the difference between the voltage at the center point 2 of the valve group and the voltage at the end 3 of the starting end 1 and the average value exceeds a certain threshold, a fault flag is generated.

[0026] The valve group voltage is calculated using the following formula: ; The voltage symmetry is verified based on the voltage at the center point 2 of the valve group, specifically as follows: .

[0027] The high-speed differential comparator uses an isolated comparator chip with a response time of ≤50ns.

[0028] The optical fiber communication interface integrates an SFP optical module, supports full-duplex communication, and exchanges zero-crossing time and fault status data with the valve group through the valve group optical fiber input port 4.

[0029] The power supply module includes: A high-frequency current transformer is used to sense the high-frequency current at the high-frequency current extraction terminal 6 of the valve group. The rectifier and voltage regulator circuit is used to convert the induced current into a 3.3V / 5V DC power supply.

[0030] The logic processor integrates a redundancy protection mechanism and is configured as follows: When three consecutive cycles of voltage asymmetry are detected, a valve group lockout command is sent through the fiber optic communication interface. The remaining voltage that the thyristor can withstand is calculated in real time. If it exceeds 115% of the rated voltage, an emergency shutdown is triggered.

[0031] The zero-crossing detection method based on the above-mentioned high-voltage TSC reactive power compensation device includes the following steps: S1: The voltage signals at the valve group start end 1, valve group center point 2 and valve group end 3 are acquired in real time through the symmetrical voltage divider resistor module; S2: Based on the voltage signal, the zero-crossing detection control unit calculates the voltage across the valve group in real time using differential calculation and detects its zero-crossing point; S3: The zero-crossing detection result is fed back to the valve group through the fiber optic communication port; S4: Receive the switching command sent by the valve group through the switching command port 5; S5: Triggering the switching of the thyristor valve group at the zero crossing point.

[0032] The triggering control of step S5 includes: The switching will only be performed if the following conditions are met simultaneously: A valid zero-crossing point was detected. b receives the valve assembly's start / stop command; Valve group C has no fault indication.

[0033] Through the above steps, the zero-crossing error is reduced by using a symmetrical voltage divider network and a high-speed comparator, thereby reducing the inrush current and extending the life of the thyristor. By using a redundant protection mechanism based on voltage symmetry criteria, the circuit can be locked in advance when the third thyristor breaks down, reducing the overall breakdown failure rate, thereby reducing the risk of accidents and economic losses caused by secondary faults, improving the accuracy of the zero-crossing trigger detection circuit and reducing inrush current, and protecting the thyristors.

[0034] The embodiments of the present invention have been described in detail above with reference to the accompanying drawings. However, the present invention is not limited to the above embodiments. Within the scope of knowledge possessed by those skilled in the art, various changes can be made without departing from the spirit of the present invention.

Claims

1. A high voltage TSC reactive power compensation device based on zero crossing detection circuit comprising an electrical cabinet characterized in that: The inside of the electrical cabinet is integrated with a valve group, a symmetrical voltage division resistor module, a zero-crossing detection control unit, a fiber-optic communication interface and a power-taking power supply module; The valve group is a high-voltage switching unit composed of a plurality of thyristors connected in series; The high-voltage input end of the symmetrical voltage division resistor module is connected to the starting end of the valve group, the low-voltage output end is connected to the center point of the valve group, and the reference end is connected to the end of the valve group; the voltage sampling end of the zero-crossing detection control unit is electrically connected to the output end of the symmetrical voltage division resistor module; the fiber-optic communication interface is bidirectionally connected to the data port of the zero-crossing detection control unit through optical signals; the input end of the power-taking power supply module is connected to the high-frequency current power-taking end of the valve group, and the output end supplies power to the zero-crossing detection control unit; the instruction input end of the zero-crossing detection control unit is connected to the switching instruction port of the valve group.

2. The high voltage TSC reactive power compensation device based on zero-crossing detection circuit according to claim 1, characterized in that: The symmetrical voltage division resistor module comprises a first high-voltage resistor and a second high-voltage resistor, the first end of the first high-voltage resistor is connected to the starting end of the valve group, the second end of the high-voltage resistor is connected to the center point of the valve group, the first end of the second high-voltage resistor is connected to the center point of the valve group, and the second end of the second high-voltage resistor is connected to the end of the valve group; wherein the resistance values of the first high-voltage resistor and the second high-voltage resistor are equal, and the resistance value range is 1MΩ-10MΩ.

3. The high voltage TSC reactive power compensation device based on zero-crossing detection circuit according to claim 2, characterized in that: The center point of the valve group is a physical division point of the plurality of thyristors connected in series, and the valve group is equally divided into two sub-units of the same number of thyristors.

4. The high voltage TSC reactive power compensation device based on zero-crossing detection circuit of claim 1, wherein: The zero-crossing detection control unit comprises: a signal conditioning circuit for RC filtering and proportional attenuation of the voltages at the starting end, center point and end of the valve group; a high-speed differential comparator for real-time calculation of the valve group voltage and output of a zero-crossing pulse signal; a logic processor for verifying voltage symmetry based on the center point voltage of the valve group, and generating a fault flag when the difference between the center point voltage of the valve group and the average value of the voltages at the starting end and the end exceeds a certain threshold.

5. A high voltage TSC reactive power compensation device based on zero-crossing detection circuit according to claim 4, characterized in that: The high-speed differential comparator uses an isolated comparator chip with a response time ≤50ns.

6. A high voltage TSC reactive power compensation device based on zero-crossing detection circuit according to claim 1, characterized in that: The fiber-optic communication interface integrates an SFP optical module, supports duplex communication, and transmits the switching time and fault state data of the valve group through the fiber-optic input port and the valve group.

7. The high voltage TSC reactive power compensation device based on zero-crossing detection circuit according to claim 1, characterized in that: The power-taking power supply module comprises: a high-frequency current transformer for sensing the high-frequency current of the high-frequency current power-taking end of the valve group; a rectifier and voltage stabilizing circuit for converting the sensed current into a 3.3V / 5V DC power supply.

8. A high voltage TSC reactive power compensation device based on zero-crossing detection circuit according to claim 4, characterized in that: The logic processor integrates a redundant protection mechanism, and is configured to: send a valve group locking instruction through the fiber-optic communication interface when 3 consecutive periods of voltage asymmetry are detected; calculate the voltage borne by the remaining thyristors in real time, and trigger an emergency shutdown if the voltage exceeds 115% of the rated voltage.

9. The zero-crossing detection method of a high-voltage TSC reactive power compensation device according to any one of claims 1-8, characterized in that: The method comprises the following steps: S1: real-time acquisition of the voltage signals at the starting end, center point and end of the valve group through the symmetrical voltage division resistor module; S2: real-time differential calculation of the voltages at both ends of the valve group based on the voltage signals, and detection of the zero-crossing points thereof through the zero-crossing detection control unit; S3: feedback of the zero-crossing detection results to the valve group through the fiber-optic communication port; S4: reception of the switching instructions issued by the valve group through the switching instruction port; S5: triggering of the switching of the thyristor valve group at the zero-crossing point.

10. The zero-crossing detection method for a high-voltage TSC reactive power compensation device according to claim 9, characterized in that: The trigger control of the step S5 comprises: The switching is executed only when the following conditions are met simultaneously: a. A valid zero-crossing is detected; b. A switching instruction of the valve group is received; c. The valve group is free of fault flags.

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