Highly Reliable Fuseable MOV Protection Device for IGCT Converter Valve Based on Online Monitoring

Abstract

The present invention discloses a highly reliable fuseable MOV protection device for an IGCT converter valve based on online monitoring, belonging to the technical field of converter valve protection. It includes a fuseable MOV and a plurality of turn-off IGCT devices. A voltage monitoring module, a current monitoring module, and a temperature monitoring module are connected to the fuseable MOV, and all are signal-connected to the online monitoring module central station. The online monitoring module central station is sequentially signal-connected to a logic judgment and early warning module and an IGCT centralized control module. The IGCT centralized control module is signal-connected to a plurality of turn-off IGCT devices. The online monitoring module central station transmits the collected voltage, current, and temperature information of the fuseable MOV to the logic judgment and early warning module. Through the logic judgment and early warning module, the operating state of the fuseable MOV is judged and analyzed in real time and fed back to the IGCT centralized control module and the valve control system. When an abnormal state of the fuseable MOV occurs, the active turn-off function of the IGCT is blocked to avoid breakdown of the IGCT device or over-energy failure explosion of the fuseable MOV, realizing all-round protection of the device and improving the safety and reliability of the fuseable MOV.

Description

Technical Field

[0001] The present invention relates to the technical field of converter valve protection, and particularly to a highly reliable fuseable MOV protection device for an IGCT converter valve based on online monitoring. Background Art

[0002] High-voltage direct current (HVDC) transmission is an important part of a new power system. In traditional HVDC transmission, the converter based on thyristors has the problem of commutation failure caused by the grid voltage drop. The use of an IGCT converter with a controllable turn-off function can effectively solve the commutation failure problem, and it has now entered the critical stage of engineering application. To address the problem that the IGCT device will withstand overvoltage during the active turn-off of a large current, the method of paralleling discrete fuseable MOVs can be used to suppress the dynamic overvoltage, and a fuse is connected in series to achieve over-energy protection for the fuseable MOV. However, the MOV faces relatively complex operating conditions during operation. When abnormal states such as the breakdown failure of the fuseable MOV itself or the melting of the fuse occur, the active turn-off function of the IGCT device must be withdrawn to prevent the device from being broken down by overvoltage. At the same time, when the fuseable MOV accumulates high energy and has a high surface temperature, the active turn-off function of the IGCT device should also be withdrawn to avoid over-energy failure or explosion of the MOV. Therefore, online monitoring, judgment, and analysis of the current, voltage, temperature, and other states of the fuseable MOV to understand the operating state of the fuseable MOV are of great significance for avoiding the breakdown of the IGCT device or over-energy failure and explosion of the fuseable MOV and improving the safety and reliability of the fuseable MOV.

[0003] The patent document with publication number CN 110768226 A discloses an overvoltage protection device based on a zinc oxide varistor MOV, including: a zinc oxide varistor MOV, a circuit breaker K, and a transformer T; the incoming line end of the zinc oxide varistor MOV is connected to the incoming line end of the device, and the outgoing line end is connected to the incoming line end of the transformer T; the circuit breaker K is connected in parallel across the two ends of the zinc oxide varistor MOV; the incoming line end of the transformer T is connected to the outgoing line end of the zinc oxide varistor MOV, and the outgoing line end is connected to the outgoing line end of the device. The overvoltage protection device based on the zinc oxide varistor MOV of this invention has the advantages of simple structure, safety and reliability, and strong applicability. By connecting the zinc oxide varistor MOV in parallel between the contacts of the circuit breaker and absorbing the overvoltage energy of the system through the zinc oxide varistor MOV, the overvoltage related to the circuit breaker operation is limited to a lower level, effectively solving the system overvoltage problem. However, this invention cannot perform real-time monitoring on the operating state of the fuseable MOV inside the IGCT converter valve, thus unable to protect the IGCT device and the fuseable MOV.

[0004] The patent document with the publication number CN 116231737 A discloses an IGCT converter valve. Each IGCT stage in this solution includes an IGCT device, a buffer circuit and an IGCT arrester connected in parallel with the IGCT device respectively. A fuse is connected in series on the branch where the IGCT arrester is located, and different voltage thresholds are set to turn on the IGCT according to the normal and abnormal working states of the IGCT energy extraction and control unit. This solution can not only effectively avoid the risk of energy overlimit or even explosion of the arrester module by connecting a fuse in series on the branch where the arrester module is located, but also the two-stage overvoltage protection logic plays a dual protection role for the circuit, which can greatly improve the stability of the IGCT converter valve, thereby improving the safety of the entire DC transmission line. However, this invention cannot monitor the operating state of the fusible MOV in real time, so it is impossible to protect the IGCT device and the fusible MOV. Summary of the Invention

[0005] In view of this, in order to overcome the deficiencies of the prior art, the present invention provides a highly reliable fusible MOV protection device for an IGCT converter valve based on online monitoring, which can protect the IGCT device and the fusible MOV simultaneously, and ensure the safe and stable operation of the IGCT converter valve.

[0006] To solve the above technical problems, the technical solution adopted by the present invention is: A highly reliable fusible MOV protection device for an IGCT converter valve based on online monitoring, including a fusible MOV and a plurality of turn-off IGCT devices, the fusible MOV is used to provide overvoltage protection and absorb turn-off energy during the active turn-off process of the IGCT device;

[0007] A voltage monitoring module, a current monitoring module and a temperature monitoring module are connected to the fusible MOV, which are respectively used for online monitoring of the voltage, current and temperature of the fusible MOV;

[0008] The voltage monitoring module, the current monitoring module and the temperature monitoring module are all signal-connected to the central station of the online monitoring module. The central station of the online monitoring module is sequentially signal-connected to the logic judgment and early warning module and the IGCT centralized control module. The IGCT centralized control module is signal-connected to the plurality of turn-off IGCT devices;

[0009] The central station of the online monitoring module transmits the collected voltage, current and temperature information of the fusible MOV to the logic judgment and early warning module. The logic judgment and early warning module performs real-time judgment and analysis on the operating state of the fusible MOV and feedbacks it to the IGCT centralized control module and the valve control system. When an abnormal state of the fusible MOV occurs, the active turn-off function of the IGCT device is blocked, avoiding breakdown of the IGCT device or over-energy failure and explosion of the fusible MOV, realizing all-round protection of the IGCT device, and improving the safety and reliability of the fusible MOV.

[0010] Furthermore, it also includes a fuse and a static voltage balancing and buffer circuit. The fuse is connected in series with the fusible MOV and is used to melt when the fusible MOV is over-powered to protect the fusible MOV; the static voltage balancing and buffer circuit is connected in parallel with the fusible MOV and the turnable IGCT device to achieve dynamic and static voltage balancing of the circuit and IGCT device drive energy extraction.

[0011] Furthermore, a high-sensitivity sensor is installed at a key position of the fusible MOV, and the voltage, current and temperature information of the fusible MOV in operation are monitored in real time by the sensor, and the status information is periodically sent to the online monitoring module center.

[0012] Furthermore, the current monitoring module is a high-sensitivity and high-precision CT, which is connected in series to the fusible MOV branch. The CT probe detects the current signal of the fusible MOV branch and sends it to the online monitoring module after A / D data conversion and wireless transmission.

[0013] Furthermore, the voltage monitoring module is a high-sensitivity and high-precision voltage sensor, which is directly connected in parallel at both ends of the fusible MOV branch. The voltage sensor probe detects the voltage signal of the fusible MOV branch and sends it to the online monitoring module after A / D data conversion and wireless transmission.

[0014] Furthermore, the temperature monitoring module is a high-sensitivity and high-precision non-contact temperature sensor, and the temperature sensor probe detects the surface temperature signal of the fusible MOV and sends it to the online monitoring module after A / D data conversion and wireless transmission.

[0015] Furthermore, the logic judgment warning module analyzes and processes the monitoring results of various data to determine the operating status of the fusible MOV, and sends it to the IGCT centralized control module and the valve control system. For abnormal status of the fusible MOV, an early warning is promptly issued through sound and light to inform the operating personnel and sent to the IGCT centralized control module.

[0016] Furthermore, the IGCT centralized control module receives the fusible MOV status information sent by the logic judgment early warning module, realizes active shutdown or locking of the IGCT, and when the fusible MOV is in a normal state, allows the IGCT device to execute the valve-controlled active shutdown command, and when the fusible MOV is in an abnormal state, locks the active shutdown command issued by the valve control to protect the IGCT device from being broken down by overvoltage or protect the fusible MOV from failing and exploding due to over-energy and overheating.

[0017] Compared with the prior art, the present invention has the following beneficial effects:

[0018] The present invention installs monitoring sensors at key parts of the fuseable MOV, periodically obtains information such as current, voltage, and temperature during the operation of the fuseable MOV, and sends the relevant operation information to the online monitoring module platform through wireless remote transmission. Subsequently, the logical judgment and early warning module analyzes and judges the operation state of the fuseable MOV in real time and feeds it back to the valve control system and the IGCT centralized control module. When necessary, the active turn-off instruction is blocked to avoid the breakdown of IGCT devices or the over-energy failure and explosion of the fuseable MOV, improve the safety and reliability of the fuseable MOV, and at the same time help the operation and maintenance personnel to grasp the state of the fuseable MOV in real time and reduce the incidence of converter valve accidents. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 is a schematic structural connection diagram of an embodiment of the present invention;

[0020] In the figure, 1 - fuseable MOV, 2 - turn-off IGCT device, 3 - voltage monitoring module, 4 - current monitoring module, 5 - temperature monitoring module, 6 - online monitoring module platform, 7 - logical judgment and early warning module, 8 - IGCT centralized control module, 9 - valve control system, 10 - fuse, 11 - static voltage equalization and buffer circuit. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0021] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the drawings of the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, rather than all of the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the described embodiments of the present invention fall within the scope of protection of the present invention.

[0022] Embodiment: Refer to Figure 1 , a highly reliable fuseable MOV protection device for an IGCT converter valve based on online monitoring, including a fuseable MOV 1 and a plurality of turn-off IGCT devices 2, and the fuseable MOV 1 is used to provide overvoltage protection and absorb turn-off energy during the active turn-off process of the IGCT device;

[0023] A voltage monitoring module 3, a current monitoring module 4, and a temperature monitoring module 5 are connected to the fuseable MOV 1, and are respectively used for online monitoring of the voltage, current, and temperature of the fuseable MOV 1;

[0024] The voltage monitoring module 3, the current monitoring module 4, and the temperature monitoring module 5 are all signal-connected to the online monitoring module platform 6, the online monitoring module platform 6 is sequentially signal-connected to the logical judgment and early warning module 7 and the IGCT centralized control module 8, and the IGCT centralized control module 8 is signal-connected to the plurality of turn-off IGCT devices 2;

[0025] The online monitoring module middle station 6 transmits the collected voltage, current, and temperature information of the fuseable MOV1 to the logic judgment and early warning module 7. The logic judgment and early warning module 7 performs real-time judgment and analysis on the operating state of the fuseable MOV1 and feeds it back to the IGCT centralized control module 8 and the valve control system 9. When an abnormal state of the fuseable MOV1 occurs, the active turn-off function of the IGCT device is blocked, avoiding the breakdown of the IGCT device or the over-energy failure explosion of the fuseable MOV, realizing all-round protection of the IGCT device, and improving the safety and reliability of the fuseable MOV.

[0026] It also includes a fuse 10 and a static voltage equalizing and buffering circuit 11. The fuse 10 is connected in series with the fuseable MOV1 and is used to fuse when the fuseable MOV1 has excessive energy, protecting the fuseable MOV1. The static voltage equalizing and buffering circuit 11 is connected in parallel with the fuseable MOV1 and the turn-off IGCT device 2 and is used to realize dynamic and static voltage equalization of the loop and energy extraction for driving the IGCT device.

[0027] The static voltage equalizing and buffering circuit 11 includes multiple sub-circuits. One sub-circuit is connected in parallel to each turn-off IGCT device. The sub-circuit includes a capacitor and two resistors. The capacitor is connected in series with one of the resistors and then in parallel with the other resistor.

[0028] A high-sensitivity sensor is installed at the key position of the fuseable MOV1. The sensor monitors the voltage, current, and temperature information during the operation of the fuseable MOV1 in real time and periodically sends the status information to the online monitoring module middle station 6.

[0029] The current monitoring module 4 is a high-sensitivity and high-precision CT, which is connected in series in the branch of the fuseable MOV1. The CT probe detects the current signal of the fuseable MOV1 branch and sends it to the online monitoring module middle station 6 after A / D data conversion and wireless transmission.

[0030] The voltage monitoring module 3 is a high-sensitivity and high-precision voltage sensor, which is directly connected in parallel across the two ends of the branch of the fuseable MOV1. The voltage sensor probe detects the voltage signal of the fuseable MOV1 branch and sends it to the online monitoring module middle station 6 after A / D data conversion and wireless transmission.

[0031] The temperature monitoring module 5 is a high-sensitivity and high-precision non-contact temperature sensor. The temperature sensor probe detects the surface temperature signal of the fuseable MOV1 and sends it to the online monitoring module middle station 6 after A / D data conversion and wireless transmission.

[0032] The logic judgment and warning module 7 analyzes and processes the monitoring results of various data, judges the operating state of the fuseable MOV1, and sends it to the IGCT centralized control module 8 and the valve control system 9. For the abnormal state of the fuseable MOV1, it timely gives an alarm through sound and light to inform the operator and sends it to the IGCT centralized control module 8.

[0033] The judgment logic of the logic judgment and warning module 7 includes:

[0034] Logic 1: If I = 0, V ≥ V ref , T ≥ T ref , then over-energy fusing alarm, and the active shutdown function exits;

[0035] Logic 2: If I ≥ I ref , V = 0, T ≥ T ref , then over-energy short-circuit alarm, and the active shutdown function exits;

[0036] Logic 3: If I / U conforms to the volt-ampere characteristic curve of the fuseable MOV, then further judge the relationship between T and T off : If T < T off , then the fuseable MOV is in a normal state. If T ≥ T off , then the fuseable MOV is overheated and the active shutdown function exits;

[0037] Others: Abnormal alarm, please manually judge the state of the monitoring sensor.

[0038] The IGCT centralized control module 8 receives the status information of the fuseable MOV1 sent by the logic judgment and warning module 7, and realizes the active shutdown or locking of the IGCT. When the status of the fuseable MOV1 is normal, it allows the IGCT device to execute the active shutdown command of the valve control. When the status of the fuseable MOV1 is abnormal, it locks the active shutdown instruction issued by the valve control to protect the IGCT device from being broken down by overvoltage or protect the fuseable MOV1 from failing and exploding due to over-energy and overheating.

[0039] The above is the preferred embodiment of the present invention. It should be pointed out that for those of ordinary skill in the art, without departing from the principle of the present invention, several improvements and refinements can still be made, and these improvements and refinements should also be regarded as the protection scope of the present invention.

Claims

1. A highly reliable fuseable MOV protection device for IGCT converter valves based on on-line monitoring, characterized in that: It includes a fuseable MOV and multiple turn-off IGCT devices. The multiple turn-off IGCT devices are connected in series and then connected in parallel with the fuseable MOV. The fuseable MOV is used to provide overvoltage protection and absorb turn-off energy during the active turn-off process of the IGCT devices; A voltage monitoring module, a current monitoring module, and a temperature monitoring module are connected to the fuseable MOV, which are respectively used for on-line monitoring of the voltage, current, and temperature of the fuseable MOV; The voltage monitoring module, the current monitoring module, and the temperature monitoring module are all signal-connected to the middle station of the on-line monitoring module. The middle station of the on-line monitoring module is sequentially signal-connected to the logic judgment and early warning module and the IGCT centralized control module. The IGCT centralized control module is signal-connected to the multiple turn-off IGCT devices; The middle station of the on-line monitoring module transmits the collected voltage, current, and temperature information of the fuseable MOV to the logic judgment and early warning module. The logic judgment and early warning module performs real-time judgment and analysis on the operating state of the fuseable MOV and feeds it back to the IGCT centralized control module and the valve control system. When an abnormal state of the fuseable MOV occurs, the active turn-off function of the IGCT device is blocked to avoid breakdown of the IGCT device or over-energy failure explosion of the fuseable MOV, realizing all-round protection of the IGCT device and improving the safety and reliability of the fuseable MOV; It also includes a fuse and a static voltage equalizing and buffering circuit. The fuse is connected in series with the fuseable MOV and is used to fuse when the fuseable MOV has excessive energy to protect the fuseable MOV; the static voltage equalizing and buffering circuit is connected in parallel with the fuseable MOV and the turn-off IGCT devices and is used to achieve dynamic and static voltage equalization of the loop and energy extraction for driving the IGCT devices; the static voltage equalizing and buffering circuit includes multiple sub-circuits, and each turn-off IGCT device is connected in parallel with one of the sub-circuits. Each sub-circuit includes a capacitor and two resistors. The capacitor is connected in series with one of the resistors and then connected in parallel with the other resistor; High-sensitivity sensors are installed at key positions of the fuseable MOV to monitor the voltage, current, and temperature information during the operation of the fuseable MOV in real time through the sensors, and the status information is periodically sent to the middle station of the on-line monitoring module; the current monitoring module is a high-sensitivity and high-precision CT, which is connected in series in the fuseable MOV branch. The CT probe detects the current signal of the fuseable MOV branch and sends it to the middle station of the on-line monitoring module after A / D data conversion and wireless transmission; the voltage monitoring module is a high-sensitivity and high-precision voltage sensor, which is directly connected in parallel at both ends of the fuseable MOV branch. The voltage sensor probe detects the voltage signal of the fuseable MOV branch and sends it to the middle station of the on-line monitoring module after A / D data conversion and wireless transmission; the temperature monitoring module is a high-sensitivity and high-precision non-contact temperature sensor. The temperature sensor probe detects the surface temperature signal of the fuseable MOV and sends it to the middle station of the on-line monitoring module after A / D data conversion and wireless transmission; The logic judgment and early warning module analyzes and processes the monitoring results of various data, judges the operating state of the fusible MOV, and sends it to the IGCT centralized control module and the valve control system. For the abnormal state of the fusible MOV, an early warning is timely given through sound and light to inform the operator and sent to the IGCT centralized control module; The judgment logic of the logic judgment and early warning module includes: Logic 1: If I = 0, V ≥ V ref , T ≥ T ref , then over-power fusing alarm is triggered and the active shutdown function exits; Logic 2: If I ≥ I ref , V = 0, T ≥ T ref , then over-power short circuit alarm is triggered and the active shutdown function exits; Logic 3: If the I / U conforms to the volt-ampere characteristic curve of the fuseable MOV, further judge the relationship between T and T off : If T < T off , the fuseable MOV is in a normal state. If T ≥ T off , the fuseable MOV is overheated and the active shutdown function exits; Others: Abnormal alarm, please manually judge the state of the monitoring sensor; The IGCT centralized control module receives the status information of the fusible MOV sent by the logic judgment and early warning module, and realizes the active shutdown or locking of the IGCT. When the state of the fusible MOV is normal, the IGCT device is allowed to execute the active shutdown command of the valve control. When the state of the fusible MOV is abnormal, the active shutdown instruction issued by the valve control is locked to protect the IGCT device from being broken down by overvoltage or to protect the fusible MOV from failing and exploding due to overenergy and overheating.

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