Voltage sag treatment system and method, controller and storage medium

Abstract

The invention relates to a voltage sag treatment system and method, a controller and a storage medium. A thyristor module of the system is connected with a current transformation module, one end of a first switch and a load; the converter module is also connected with the charging module, the super capacitor management system and the load. The charging module is also connected with one end of the second switch; the other end of the second switch is connected with the other end of the first switch and is connected with power grid input voltage; one end of the DC-DC converter is respectively connected with the charging module and the converter module, and the other end of the DC-DC converter is connected with the super capacitor management system; in the grid-connected and off-grid mode, the first switch is switched on, the second switch is switched off, and when voltage sag occurs in the input voltage of the power grid, the thyristor module is switched off; and in the flexible interconnection mode, the first switch is switched off, and the second switch is switched on. According to the invention, voltage sag treatment can be carried out for multiple scenes, and the reliability of the system is effectively improved.

Description

Technical Field

[0001] This application relates to the field of power quality management technology, and in particular to a voltage sag management system, method, controller and storage medium. Background Technology

[0002] With the development of power grid infrastructure, power quality problems have become increasingly prominent, especially in industrial production, where voltage dips occur frequently, seriously affecting the normal operation of power grid equipment.

[0003] Voltage sags refer to the phenomenon of a sudden drop in the effective voltage value followed by a rapid recovery. They are mostly occasional, sudden events, lasting less than one second, and their depth is usually within 30%. Voltage sags primarily occur in power transmission and distribution systems, easily triggering the undervoltage protection function of frequency converters and causing production line shutdowns, resulting in economic losses.

[0004] However, traditional voltage sag mitigation solutions can only address voltage sags in a single scenario, making it difficult to migrate and apply them across different production scenarios, which hinders the widespread adoption of voltage sag mitigation solutions in power grid infrastructure. Summary of the Invention

[0005] Therefore, it is necessary to provide a voltage sag management system, method, controller, and storage medium that can be applied to various production scenarios to address the above-mentioned technical problems.

[0006] In a first aspect, this application provides a voltage sag mitigation system, including a thyristor module, a converter module, a charging module, a supercapacitor management system, a first switch, and a second switch;

[0007] The thyristor module is connected to the converter module, one end of the first switch and the load respectively; the converter module is also connected to the charging module, the supercapacitor management system and the load respectively; the charging module is also connected to one end of the second switch; the other end of the second switch is connected to the other end of the first switch and connected to the grid input voltage; one end of the DC-DC converter is connected to the charging module and the converter module respectively, and the other end of the DC-DC converter is connected to the supercapacitor management system.

[0008] In the grid-connected / off-grid mode, the first switch is turned on and the second switch is turned off, and the thyristor module is turned off when the grid input voltage experiences a voltage dip; in the flexible interconnection mode, the first switch is turned off and the second switch is turned on.

[0009] In one embodiment, the system further includes a third switch and a fourth switch;

[0010] One end of the third switch is connected to the thyristor module and the converter module respectively, and the other end of the third switch is used to connect to the load.

[0011] One end of the fourth switch is connected to the other end of the first switch and the other end of the second switch, and the other end of the fourth switch is connected between the other end of the third switch and the load.

[0012] In the safety isolation mode, the third switch is off and the fourth switch is on.

[0013] In one embodiment, the converter module includes multiple cascaded H-bridge inverter units, and the multiple cascaded H-bridge inverter units constitute a multi-level inverter topology.

[0014] In one embodiment, the converter module includes a first inverter unit and a second inverter unit connected in parallel; the first inverter unit includes a fifth switch and a first PCS connected in series; the second inverter unit includes a sixth switch QF6 and a second PCS connected in series.

[0015] The first PCS includes multiple cascaded first H-bridge inverter units; the second PCS includes multiple cascaded second H-bridge inverter units.

[0016] In the parallel-off-grid mode, the fifth switch is on and the sixth switch QF6 is off; in the flexible interconnection mode, the fifth switch is off and the sixth switch QF6 is on.

[0017] In one embodiment, the first PCS includes a first preset number of cascaded first H-bridge inverter units, each of which includes two IGBTs;

[0018] The second PCS includes a second preset number of second H-bridge inverter units, and the second H-bridge inverter unit includes two MOSFETs.

[0019] In one embodiment, the system further includes a control module and a communication module; the control module further includes a first control unit, a second control unit, and a third control unit; the communication module includes a first communication unit and a second communication unit;

[0020] The first control unit is connected to the first PCS via a first communication unit; the second control unit is connected to the second PCS via a second communication unit.

[0021] In the grid-connected / off-grid mode, the third control unit controls the first and fifth switches to be turned on, and the second and sixth switches QF6 to be turned off; in the flexible interconnection mode, the third control unit controls the first and fifth switches to be turned off, and the second and sixth switches QF6 to be turned on.

[0022] In one embodiment, the supercapacitor management system further includes a backup power module;

[0023] The backup power module is used to power the server of the supercapacitor management system in the event of a power grid failure.

[0024] Secondly, this application provides a voltage sag mitigation method, applied to a voltage sag mitigation system as described in any embodiment of the first aspect; the method includes:

[0025] In grid-connected and off-grid mode, the first switch is turned on and the second switch is turned off, and the thyristor module is turned off when the grid input voltage experiences a voltage dip.

[0026] In flexible interconnection mode, the first switch is turned off and the second switch is turned on.

[0027] Thirdly, this application provides a controller, including a memory and a processor, wherein the memory stores a computer program, and the processor executes the computer program to implement the steps of the method described in the second aspect.

[0028] Fourthly, this application provides a computer-readable storage medium having a computer program stored thereon, which, when executed by a processor, implements the steps of the method described in the second aspect.

[0029] The aforementioned voltage sag mitigation system, method, controller, and storage medium include a thyristor module connected to a converter module, one end of a first switch, and a load. The converter module is also connected to a charging module, a supercapacitor management system, and the load. The charging module is connected to one end of a second switch, and the other end of the second switch is connected to the other end of the first switch and connected to the grid input voltage. Specifically, in grid-connected / off-grid mode, the first switch is on and the second switch is off; when a voltage sag occurs in the grid input voltage, the thyristor module disconnects. In flexible interconnection mode, the first switch is off and the second switch is on. Through these methods, this application can select different operating modes for different production application scenarios (e.g., factory, harsh environment power supply), to effectively mitigate voltage sags and promote the application of voltage sag mitigation solutions in grid infrastructure. Attached Figure Description

[0030] To more clearly illustrate the technical solutions in the embodiments of this application or related technologies, the drawings used in the description of the embodiments of this application or related technologies will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort.

[0031] Figure 1 This is a schematic diagram of the voltage sag mitigation system in one embodiment;

[0032] Figure 2 This is a schematic diagram of the voltage sag mitigation system in another embodiment;

[0033] Figure 3 This is a schematic diagram of the voltage sag mitigation system in another embodiment;

[0034] Figure 4 This is a flowchart illustrating a voltage sag mitigation method in one embodiment;

[0035] Figure 5 This is an internal structural diagram of a computer device in one embodiment. Detailed Implementation

[0036] To make the objectives, technical solutions, and advantages of this application clearer, the following detailed description is provided in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the scope of this application.

[0037] It should be noted that the terms "first," "second," etc., used in this application can be used to describe various elements, but these elements are not limited by these terms. These terms are only used to distinguish the first element from the second element. The terms "comprising" and "having," and any variations thereof, used in this application, are intended to cover non-exclusive inclusion. The term "multiple" used in this application refers to two or more. The term "and / or" used in this application refers to one of the embodiments, or any combination of multiple embodiments.

[0038] It should be noted that traditional voltage sag mitigation solutions mainly employ real-time online series compensation and offline parallel inverter compensation methods. Real-time online series compensation does not require energy storage devices, but its equipment cannot meet the line's compensation requirements in the event of deep voltage drops or short-term interruptions. While offline parallel inverter compensation can achieve deep compensation over a wide range, it is limited by energy storage capacity and is not suitable for dealing with frequent voltage drops. Furthermore, it suffers from high energy consumption and high maintenance costs.

[0039] In practical applications, traditional voltage sag mitigation solutions have the following drawbacks:

[0040] ① Traditional voltage sag mitigation devices are insufficient in terms of response speed and capacity utilization, making it difficult to meet the voltage sag compensation needs of sensitive loads. Especially when the grid input voltage and frequency change, traditional voltage sag mitigation devices cannot effectively ensure that the grid input phase remains unchanged, affecting the stable operation of the load.

[0041] ② Traditional voltage sag mitigation schemes are insufficient in terms of intelligence, making it difficult to implement more flexible adaptive control strategies and unable to automatically adjust the system's operating status and control strategies based on real-time monitoring and analysis of the power grid status.

[0042] ③ Traditional offline parallel inverter compensation methods are limited by energy storage capacity, are not suitable for dealing with frequent voltage drops, and have high energy consumption and maintenance costs.

[0043] ④ Under abnormal conditions such as voltage sags, traditional voltage sag mitigation solutions cannot guarantee the power supply reliability of sensitive loads, cannot effectively prevent energy storage converters from providing large inrush currents to the loads, and are also difficult to achieve smooth switching and flexible exit control.

[0044] ⑤ Traditional voltage sag mitigation schemes still need optimization in terms of voltage recovery control strategies, making it difficult to achieve rapid compensation and recovery of voltage sags, which affects the stability and reliability of voltage quality.

[0045] There is an urgent need for a voltage sag mitigation solution that is low in investment cost, can fully meet the requirements for voltage sag and short-term interruption, and is applicable to various production application scenarios. To address the above issues, this application provides a voltage sag mitigation system.

[0046] In one exemplary embodiment, such as Figure 1 As shown, this application provides a voltage sag control system, including a thyristor module, a converter module, a charging module, a supercapacitor management system, a first switch QF1, and a second switch QF2;

[0047] The thyristor module is connected to the converter module, one end of the first switch QF1, and the load respectively; the converter module is also connected to the charging module, the supercapacitor management system, and the load respectively; the charging module is also connected to one end of the second switch QF2; the other end of the second switch QF2 is connected to the other end of the first switch QF1 and connected to the grid input voltage; one end of the DC-DC converter is connected to the charging module and the converter module respectively, and the other end of the DC-DC converter is connected to the supercapacitor management system.

[0048] In the grid-connected / off-grid mode, the first switch QF1 is turned on and the second switch QF2 is turned off. When the grid input voltage experiences a voltage dip, the thyristor module is turned off. In the flexible interconnection mode, the first switch QF1 is turned off and the second switch QF2 is turned on.

[0049] For example, the thyristor module may include an STS thyristor, a voltage detection unit, and a comparator unit, used to detect the state of the grid input voltage through the voltage detection unit and the comparator unit, and to perform fast switching control using the STS thyristor according to the state of the grid input voltage. Optionally, the STS thyristor of the thyristor module may be an STS thyristor with a rated voltage of 1200V and a rated current of 120A, the voltage detection unit of the thyristor module may be a PT100 type voltage transformer with an accuracy of 0.5 class, and the comparator unit of the thyristor module may be an ADL561J type digital comparator with an accuracy of ±0.1%.

[0050] In some examples, the converter module can be used to implement multi-level inversion of the circuit. Optionally, the converter module may include a PCS (Power Conversion System).

[0051] For example, the charging module may include multiple rectifiers for charging the supercapacitor using the grid input voltage and for supplying power to the load via a converter module. Optionally, the charging module may include three parallel 20kW three-phase PWM rectifier modules, each of which can convert three-phase AC power into stable DC power.

[0052] Furthermore, the Supercapacitor Management System (CMS) incorporates supercapacitor modules, which can be used for control, monitoring, protection, and optimization. In practical applications, the supercapacitor module can be composed of clusters of 3.0V / 1.88Wh supercapacitor cells, with a rated voltage of 540V and a capacity of 338.4Wh (based on a 1P180S configuration).

[0053] In some possible implementations, a DC-DC converter (Direct Current to Direct Current Converter) can be used to adjust the output mode during supercapacitor discharge. Optionally, the rated power of the DC-DC converter can be 50kW.

[0054] Specifically, when the second switch QF2 of the voltage sag mitigation system is open and the first switch QF1 is closed, the voltage sag mitigation system operates in grid-connected / off-grid mode (also known as thyristor fast grid-connected / off-grid mode or thyristor mode). In this mode, the STS thyristor in the thyristor module acts as a fast switch and will quickly disconnect when a voltage sag occurs in the grid. At this time, the output voltage of the supercapacitor is boosted by the DC-DC converter and then inverted by the converter module to supply power to the load. When the grid is restored, the STS thyristor in the thyristor module can be turned on by phase-locked synchronization control.

[0055] For example, when a voltage sag occurs and the grid input voltage exceeds a preset threshold (e.g., -20% to 20%), the system can control the STS thyristor to disconnect. The output voltage of the supercapacitor module is boosted to 650V by a DC-DC converter and then inverted into the corresponding AC power by the converter module to supply power to the load for 3 seconds (50kW). When the grid voltage recovers, the system can perform phase-locked synchronization through the PCS in the converter module and control the STS thyristor to turn on to restore grid power supply.

[0056] When the first switch QF1 of the voltage sag mitigation system is open and the second switch QF2 is closed, the system operates in flexible interconnection mode (also known as flexible DC interconnection mode or charging module mode). In this mode, when the power grid is operating normally, the DC-DC converter operates in constant current mode. The grid input voltage, after being rectified by the charging module, can charge the supercapacitor. The grid input voltage can also supply power to the load sequentially through the charging module and the converter module. It can be understood that the supercapacitor in the supercapacitor management system is in a hot standby state at this time. When a power grid fault occurs (voltage sag or even line disconnection), the DC-DC converter switches to high-voltage side constant voltage mode, and the supercapacitor in the supercapacitor management system continuously discharges, thereby supplying power to the load through the converter module. Optionally, in flexible interconnection mode, the discharge time of the supercapacitor can depend on the load size and the lower limit of the supercapacitor voltage protection.

[0057] It should be noted that the aforementioned voltage sag mitigation system, operating in both parallel and off-grid modes, can effectively address frequent and brief voltage sags and transient interruptions. For example, for voltage drops of extremely short duration (milliseconds to seconds) caused by events such as the starting of large motors, welding machine operation, or short-circuit faults in a factory, the STS thyristor, being a hard switch based on voltage amplitude, has an extremely fast response speed (microseconds). This allows the voltage sag mitigation system to instantly disconnect the abnormal power grid and switch to supercapacitor power supply without affecting the load, thus effectively mitigating the vast majority of voltage sags with an extremely fast response speed.

[0058] The voltage sag mitigation system described above, through its charging module mode, can effectively address complex power grid issues such as prolonged voltage interruptions and frequency fluctuations in scenarios where loads have high power quality requirements. For example, using the system's charging module mode, it can supply power to data center servers, precision medical equipment, semiconductor production lines, and high-end laboratory instruments—equipment with high power quality requirements—in scenarios where power outages lasting several seconds or even minutes may occur due to line maintenance, remote faults, or severe weather.

[0059] In one embodiment, such as Figure 2 As shown, the system also includes a third switch QF3 and a fourth switch QF4;

[0060] One end of the third switch QF3 is connected to the thyristor module and the converter module respectively, and the other end of the third switch QF3 is used to connect the load.

[0061] One end of the fourth switch QF4 is connected to the other end of the first switch QF1 and the other end of the second switch QF2, and the other end of the fourth switch QF4 is connected between the other end of the third switch QF3 and the load.

[0062] In the safety isolation mode, the third switch QF3 is open and the fourth switch QF4 is on.

[0063] For example, the safety isolation mode (also known as the safety operation mode - maintenance bypass mode) is used to completely isolate the charging module, converter module, DC-DC converter and supercapacitor management system from the grid and the load when the system needs maintenance or a fault occurs inside the system (such as damage to STS thyristors, PCS energy storage converters, etc.) while ensuring that the load is not powered off. This allows for maintenance of these modules and improves the overall reliability of the system.

[0064] In one embodiment, the converter module includes multiple cascaded H-bridge inverter units, and the multiple cascaded H-bridge inverter units constitute a multi-level inverter topology.

[0065] For example, the converter module can adopt a multi-level inverter topology and consist of multiple cascaded H-bridge inverter units to achieve power conversion.

[0066] In one embodiment, such as Figure 3 As shown, the converter module includes a first inverter unit and a second inverter unit connected in parallel; the first inverter unit includes a fifth switch QF5 and a first PCS 112 connected in series; the second inverter unit includes a sixth switch QF6 and a second PCS 114 connected in series.

[0067] The first PCS 112 includes multiple cascaded first H-bridge inverter units; the second PCS 114 includes multiple cascaded second H-bridge inverter units.

[0068] In the grid-connected / off-grid mode, the fifth switch QF5 is turned on and the sixth switch QF6 is turned off; in the flexible interconnection mode, the fifth switch QF5 is turned off and the sixth switch QF6 is turned on.

[0069] For example, the circuit structures of the first PCS 112 and the second PCS 114 are different. The first H-bridge inverter unit of the first PCS 112 can be composed of multiple IGBTs, while the second H-bridge inverter unit of the second PCS 114 can be composed of multiple MOSFETs.

[0070] In practical applications, a transformer T is also installed between the voltage sag mitigation system and the power grid to convert the line voltage of the power grid into the required input voltage.

[0071] Specifically, in the grid-connected / off-grid mode, the fifth switch QF5 of the system is turned on and the sixth switch QF6 is turned off, so that the first inverter unit can be used in the system to perform inverter processing on the input signal; in the flexible interconnection mode, the fifth switch QF5 is turned off and the sixth switch QF6 is turned on, so that the second inverter unit can be used in the system to perform inverter processing on the input signal.

[0072] In one embodiment, the first PCS 112 includes a first preset number of cascaded first H-bridge inverter units, each of which includes two IGBTs;

[0073] The second PCS 114 includes a second preset number of second H-bridge inverter units, each of which includes two MOSFETs.

[0074] For example, the first preset quantity can be 27, that is, the first PCS 112 can include 27 cascaded first H-bridge inverter units, and each first H-bridge inverter unit includes two IGBTs to form a 27-level cascaded H-bridge (IGBT) structure.

[0075] In some examples, the second preset number can be 21, that is, the second PCS 114 includes 21 second H-bridge inverter units, and each second H-bridge inverter unit includes two MOSFETs to form a 21-level cascaded H-bridge (MOSFET) structure.

[0076] It should be noted that in grid-connected / off-grid mode (i.e., thyristor mode), the aforementioned 27-level cascaded H-bridge structure can generate a stepped voltage waveform that is extremely close to a sine wave, resulting in a very low total harmonic distortion (THD). It can be understood that by utilizing this structure, the operational quality of precision equipment can be guaranteed to the greatest extent possible during the brief period of emergency power supply to the load, thereby avoiding the introduction of new power quality problems due to voltage dips.

[0077] In the flexible interconnection mode (charging module mode), the aforementioned 21-level cascaded H-bridge structure achieves superior conduction losses (especially in the low-to-medium power range, where MOSFET conduction losses are typically superior to IGBTs). Furthermore, the 21-level topology, while ensuring a good output waveform, reduces the number of switching devices and isolation power supplies, thereby effectively reducing system complexity. It can be understood that this structure significantly reduces the no-load and light-load losses of the converter module under normal grid conditions (the charging module supplies power to the bus), thus effectively improving the overall system energy efficiency, which is crucial for 24 / 7 uninterrupted operation.

[0078] In one embodiment, the system further includes a control module and a communication module; the control module further includes a first control unit, a second control unit, and a third control unit; the communication module includes a first communication unit and a second communication unit;

[0079] The first control unit is connected to the first PCS 112 via the first communication unit; the second control unit is connected to the second PCS 114 via the second communication unit.

[0080] In the grid-connected / off-grid mode, the third control unit controls the first switch QF1 and the fifth switch QF5 to be turned on, and the second switch QF2 and the sixth switch QF6 to be turned off; in the flexible interconnection mode, the third control unit controls the first switch QF1 and the fifth switch QF5 to be turned off, and the second switch QF2 and the sixth switch QF6 to be turned on.

[0081] For example, the first control unit can be a DSP (Digital Signal Processor Controller), which can communicate with the first PCS 112 via a CAN (Controller Area Network) bus through a first communication unit to control the first PCS 112 to perform converter operations according to instructions. Optionally, the DSP controller's main frequency can be 150MHz. It can be understood that the core of the above-mentioned grid-connected / off-grid mode (i.e., thyristor mode) is "fast" and "accurate." In this mode, the controller needs to have extremely high real-time performance to execute the phase-locked loop (PLL) algorithm to ensure that synchronous grid connection can be completed quickly and smoothly the instant the grid is restored. The DSP controller is specifically designed for complex mathematical operations (such as trigonometric functions, PID control, and PWM generation), and its high main frequency gives it a natural advantage in handling various tasks in the grid-connected / off-grid mode.

[0082] Furthermore, the data acquisition module of the first communication unit can use an NI USB-6211 data acquisition unit (sampling frequency 50kHz), with the communication interface adopting the RS485 protocol. It should be noted that the communication content in the parallel-off-grid mode mainly consists of critical switching commands, status variables, and synchronization signals. The data volume is small, but high reliability and determinism are required. RS485 and CAN bus are mature industrial fieldbus solutions with strong anti-interference capabilities and stable latency, making them very suitable for transmitting control commands in parallel-off-grid mode. In addition, thyristor mode is extremely sensitive to instantaneous voltage changes, requiring a very high sampling rate to capture the instantaneous details of voltage dips. This embodiment uses a high sampling rate (sampling frequency reaching 50kHz) NI USB-6211 data acquisition unit to provide reliable data support for the fast switching control algorithm.

[0083] For example, the second control unit can employ an ARM (Advanced RISC Machine) controller, which can communicate with the second PCS 114 via Ethernet to control the first PCS 112 to perform converter operations according to instructions. Optionally, the ARM controller can be an STM32F407 with a main frequency of 168MHz. It can be understood that the core of the above flexible interconnect mode (i.e., the charging module mode) is "stability" and "management." In this mode, the system's operating state is stable, but it needs to manage more components (such as the charging module requiring multiple rectifiers), handle more complex system state machines, and run more advanced communication protocols. The ARM controller has richer peripheral interfaces and stronger general-purpose computing capabilities, making it more suitable for handling various tasks in the flexible interconnect mode.

[0084] Furthermore, the data acquisition module of the second communication unit can use a Keysight 34465A digital multimeter (sampling frequency 10kHz), and the communication interface of the second communication unit adopts the Ethernet protocol. It is understandable that the flexible interconnection mode (i.e., the charging module mode) requires uploading a large amount of operational data (such as the operating parameters, historical records, and power quality analysis data of each module) to the upper-level EMS (Energy Management System). When dealing with large amounts of data, the high bandwidth advantage of the Ethernet in the second communication unit is significant, facilitating remote and efficient centralized monitoring by the control center. In addition, the high accuracy and stability of the Keysight multimeter are also more suitable for long-term performance monitoring and metering.

[0085] For example, the third control unit can be used to control the on / off state of each switch (including the first switch QF1, the second switch QF2, the third switch QF3, the fourth switch QF4, etc.) in the voltage sag mitigation system, as well as control the operating state of the charging module, the supercapacitor management system, the thyristor module, and the DC-DC converter, thereby realizing the switching function of the voltage sag mitigation system between different modes (grid-connected mode, flexible interconnection mode, and safety isolation mode).

[0086] In one exemplary embodiment, the supercapacitor management system further includes a backup power module;

[0087] The backup power module is used to power the server of the supercapacitor management system in the event of a power grid failure.

[0088] For example, the backup power module may include a lead-acid battery pack. The lead-acid battery pack may consist of two 12V / 5Ah batteries, with a rated capacity of 12V × 5Ah × 2 = 120Wh.

[0089] In practical applications, the total backup power capacity of the backup power module needs to meet the requirement of continuously powering the server of the supercapacitor management system for 1 hour in the event of a power grid failure.

[0090] In some possible implementations, such as Figure 3 As shown, a seventh switch QF7 is also installed between the DC-DC converter and the supercapacitor management system. This seventh switch isolates the supercapacitor management system from components such as the thyristor module and converter module within the system, facilitating the inspection and maintenance of the supercapacitor management system. Optionally, all switches in the voltage sag mitigation system are circuit breakers.

[0091] It is understandable that, compared with traditional technologies, implementing the solution of this application can achieve at least the following beneficial effects:

[0092] ①This application adopts a fast grid connection and disconnection scheme using STS thyristors in conjunction with PCS energy storage converters. Through the fast switching action of the thyristors, a fast response and switching to voltage sag is achieved, which significantly improves the system's response speed and capacity utilization, and can meet the voltage sag compensation requirements of sensitive loads.

[0093] ②This application ensures stable load operation by maintaining the grid input phase unchanged when the grid input voltage and frequency change, effectively solving the problem that voltage sag mitigation devices in traditional technologies are unable to cope with changes in grid conditions.

[0094] ③ This application uses supercapacitors as energy storage devices, combined with DC-DC converters and converter modules, to achieve rapid compensation and recovery of voltage sags, overcoming the problems of traditional offline parallel inverter compensation methods being limited by energy storage capacity and high energy consumption.

[0095] ④ This application effectively avoids the inrush current supplied by the PCS energy storage converter to the load through a smooth switching and flexible exit control strategy, ensuring the power supply reliability of sensitive loads and improving the stability and reliability of the system.

[0096] ⑤ This application realizes intelligent control of the system through the phase-locked synchronization mechanism between the communication line and the PCS energy storage converter. It can automatically adjust the operating status according to the real-time monitored power grid status, thereby improving the system's adaptability and flexibility.

[0097] In one exemplary embodiment, this application provides a voltage sag mitigation method, applied to a voltage sag mitigation system as described in any of the above system embodiments; Figure 4 As shown, the method includes steps S402 to S404. Wherein:

[0098] Step S402: In grid-connected and off-grid mode, control the first switch to be turned on and the second switch to be turned off, and when the grid input voltage experiences a voltage dip, the thyristor module is turned off.

[0099] In step S404, under flexible interconnection mode, the first switch is turned off and the second switch is turned on.

[0100] It is understood that the solution provided by the above voltage sag mitigation method is similar to the solution described in the above system embodiments. Therefore, the specific limitations in the method embodiments of this application can be found in the limitations of the above system embodiments, and will not be repeated here.

[0101] It should be understood that although the steps in the flowcharts of the embodiments described above are shown sequentially according to the arrows, these steps are not necessarily executed in the order indicated by the arrows. Unless explicitly stated herein, there is no strict order restriction on the execution of these steps, and they can be executed in other orders. Moreover, at least some steps in the flowcharts of the embodiments described above may include multiple steps or multiple stages. These steps or stages are not necessarily completed at the same time, but can be executed at different times. The execution order of these steps or stages is not necessarily sequential, but can be performed alternately or in turn with other steps or at least some of the steps or stages in other steps. It is understood that the steps in different embodiments can be freely combined as needed, and all non-contradictory solutions formed by such combinations are within the scope of protection of this application.

[0102] In one exemplary embodiment, an electronic device is provided, which may be a server, and its internal structure diagram may be as follows: Figure 5 As shown, this electronic device includes a processor, memory, input / output (I / O) interfaces, and a communication interface. The processor, memory, and I / O interfaces are connected via a system bus, and the communication interface is also connected to the system bus via the I / O interfaces. The processor provides computational and control capabilities. The memory includes non-volatile storage media and internal memory. The non-volatile storage media stores the operating system, computer programs, and a database. The internal memory provides the environment for the operation of the operating system and computer programs stored in the non-volatile storage media. The database stores the operating data of each module of the voltage sag control system. The I / O interfaces are used for information exchange between the processor and external devices. The communication interface is used for communication with external terminals via a network connection. When the computer program is executed by the processor, it implements a voltage sag control method.

[0103] Those skilled in the art will understand that Figure 5 The structure shown is merely a block diagram of a portion of the structure related to the present application and does not constitute a limitation on the computer device to which the present application is applied. Specific computer devices may include more or fewer components than those shown in the figure, or combine certain components, or have different component arrangements.

[0104] In one embodiment, a controller is also provided, including a memory and a processor, the memory storing a computer program, the processor executing the computer program to implement the steps in the above method embodiments.

[0105] In one embodiment, a computer-readable storage medium is provided having a computer program stored thereon that, when executed by a processor, implements the steps in the method embodiments described above.

[0106] In one embodiment, a computer program product is provided, including a computer program that, when executed by a processor, implements the steps in the method embodiments described above.

[0107] Those skilled in the art will understand that all or part of the processes in the methods of the above embodiments can be implemented by a computer program instructing related hardware. The computer program can be stored in a non-volatile computer-readable storage medium, and when executed, it can include the processes of the embodiments of the above methods. Any references to memory, databases, or other media used in the embodiments provided in this application can include at least one of non-volatile memory and volatile memory. Non-volatile memory can include read-only memory (ROM), magnetic tape, floppy disk, flash memory, optical memory, high-density embedded non-volatile memory, resistive random access memory (ReRAM), magnetic random access memory (MRAM), ferroelectric random access memory (FRAM), phase change memory (PCM), graphene memory, etc. Volatile memory can include random access memory (RAM) or external cache memory, etc. By way of illustration and not limitation, RAM can take many forms, such as Static Random Access Memory (SRAM) or Dynamic Random Access Memory (DRAM). The databases involved in the embodiments provided in this application may include at least one type of relational database and non-relational database. Non-relational databases may include, but are not limited to, blockchain-based distributed databases. The processors involved in the embodiments provided in this application may be general-purpose processors, central processing units, graphics processing units, digital signal processors, programmable logic devices, quantum computing-based data processing logic devices, artificial intelligence (AI) processors, etc., and are not limited to these.

[0108] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this application.

[0109] The embodiments described above are merely illustrative of several implementation methods of this application, and while the descriptions are specific and detailed, they should not be construed as limiting the scope of this patent application. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of this application, and these all fall within the protection scope of this application. Therefore, the protection scope of this application should be determined by the appended claims.

Claims

1. A voltage sag control system, characterized in that, Includes thyristor module, converter module, charging module, supercapacitor management system, first switch, second switch and DC-DC converter; The thyristor module is connected to the converter module, one end of the first switch, and the load respectively; the converter module is also connected to the charging module, the supercapacitor management system, and the load respectively; the charging module is also connected to one end of the second switch; the other end of the second switch is connected to the other end of the first switch and connected to the grid input voltage; one end of the DC-DC converter is connected to the charging module and the converter module respectively, and the other end of the DC-DC converter is connected to the supercapacitor management system. In the grid-connected / off-grid mode, the first switch is turned on and the second switch is turned off, and the thyristor module is turned off when the grid input voltage experiences a voltage dip; in the flexible interconnection mode, the first switch is turned off and the second switch is turned on.

2. The system according to claim 1, characterized in that, The system also includes a third switch and a fourth switch; One end of the third switch is connected to the thyristor module and the converter module respectively, and the other end of the third switch is used to connect to the load; One end of the fourth switch is connected to the other end of the first switch and the other end of the second switch, and the other end of the fourth switch is connected between the other end of the third switch and the load. In the safety isolation mode, the third switch is open and the fourth switch is closed.

3. The system according to claim 1, characterized in that, The converter module includes multiple cascaded H-bridge inverter units, and the multiple cascaded H-bridge inverter units constitute a multi-level inverter topology.

4. The system according to claim 1, characterized in that, The converter module includes a first inverter unit and a second inverter unit connected in parallel; the first inverter unit includes a fifth switch and a first PCS connected in series; the second inverter unit includes a sixth switch QF6 and a second PCS connected in series. The first PCS includes multiple cascaded first H-bridge inverter units; the second PCS includes multiple cascaded second H-bridge inverter units. In the parallel-off-grid mode, the fifth switch is turned on and the sixth switch QF6 is turned off; in the flexible interconnection mode, the fifth switch is turned off and the sixth switch QF6 is turned on.

5. The system according to claim 4, characterized in that, The first PCS includes a first preset number of cascaded first H-bridge inverter units, and the first H-bridge inverter unit includes two IGBTs; The second PCS includes a second preset number of second H-bridge inverter units, and the second H-bridge inverter unit includes two MOSFETs.

6. The system according to claim 4, characterized in that, The system further includes a control module and a communication module; the control module further includes a first control unit, a second control unit, and a third control unit; the communication module includes a first communication unit and a second communication unit; The first control unit is connected to the first PCS via the first communication unit; the second control unit is connected to the second PCS via the second communication unit. The third control unit controls the first switch and the fifth switch to be turned on, and the second switch and the sixth switch QF6 to be turned off in the on-grid and off-grid mode; The third control unit controls the first switch and the fifth switch to disconnect, and the second switch and the sixth switch QF6 to connect in the flexible interconnection mode.

7. The system according to any one of claims 1 to 6, characterized in that, The supercapacitor management system also includes a backup power module; The backup power module is used to supply power to the server of the supercapacitor management system in the event of a power grid failure.

8. A method for controlling voltage sags, characterized in that, Applied to the voltage sag control system as described in any one of claims 1 to 7; the method comprises: In grid-connected and off-grid mode, the first switch is turned on and the second switch is turned off, and the thyristor module is turned off when the grid input voltage experiences a voltage dip. In flexible interconnection mode, the first switch is turned off and the second switch is turned on.

9. A controller, characterized in that, The method includes a memory and a processor, the memory storing a computer program, characterized in that the processor executes the computer program to implement the steps of the method of claim 8.

10. A computer-readable storage medium having a computer program stored thereon, characterized in that, When the computer program is executed by the processor, it implements the steps of the method of claim 8.

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