Voltage sag treatment device and method

Abstract

The invention discloses a voltage sag treatment device and method, and relates to the technical field of electric power treatment. The treatment device comprises a switch module connected in series between a power grid and a load; the high-voltage cascade energy storage device is connected to a line between the switch module and the load; the high-voltage cascade energy storage device comprises a plurality of converter modules which are sequentially connected in series and energy storage elements which are connected with the converter modules in a one-to-one correspondence mode. The controller is connected with the switch module and the high-voltage cascade energy storage device; when the voltage sag of the power grid occurs, the controller controls the switch module to cut off the power supply and controls the high-voltage cascade energy storage device to supply power to the load. Through the content of the application, unified voltage sag treatment can be carried out on the medium-high voltage power grid, the influence of the voltage sag fault of the medium-high voltage power transmission and distribution grid on the load is effectively reduced, the power supply stability is effectively improved, the loss caused by sensitive load shutdown is reduced, and the number of voltage sag treatment devices and the maintenance workload are reduced at the same time.

Description

Technical Field

[0001] This disclosure relates to the field of power management technology, and in particular to a voltage sag management device and method. Background Technology

[0002] With the rapid development of the modern power industry and the increasing proportion of power electronic equipment and precision electronic equipment in the power load of the system, voltage sags have a growing impact on power users. During power transmission and use, grid faults such as short circuits, overloads, and poor connections, as well as sudden load changes such as the starting of large motors, and natural disasters such as lightning and storms, can all cause voltage sags. Voltage sags can lead to grid instability, and prolonged voltage sags can cause loads such as motors to malfunction, potentially resulting in damage. Furthermore, voltage sags can cause malfunctions or damage to precision equipment such as power electronics, leading to production interruptions and significant economic losses.

[0003] To mitigate voltage sags and improve grid stability, voltage sag mitigation devices need to be installed at the grid or load points. Currently, most voltage sag mitigation devices are low-voltage equipment applied at the load end, mitigating voltage sags on a specific load basis. This results in a large number of devices, a lack of coordinated control between them, and an inability to manage voltage sags in medium- and high-voltage systems.

[0004] Therefore, there is a need for a high-voltage, large-capacity voltage sag control device that can be applied to medium- and high-voltage power grid systems to uniformly and centrally manage voltage sags. Summary of the Invention

[0005] This disclosure provides a voltage sag mitigation device and method, which can uniformly mitigate voltage sags in medium and high voltage power grids, effectively reduce the impact of voltage sag faults on loads in medium and high voltage transmission and distribution networks, effectively improve power supply stability, reduce losses caused by the shutdown of sensitive loads, and at the same time reduce the number of voltage sag mitigation devices and maintenance workload.

[0006] In a first aspect, this disclosure provides a voltage sag mitigation device applied to a circuit between the power grid and a load. The mitigation device includes:

[0007] A switching module connected in series between the power grid and the load;

[0008] A high-voltage cascaded energy storage device is connected to the line between the switch module and the load; the high-voltage cascaded energy storage device includes several converter modules connected in series and energy storage elements connected one-to-one with each converter module.

[0009] And a controller connected to the switch module and the high-voltage cascaded energy storage device;

[0010] When a voltage dip occurs in the power grid, the controller controls the switching module to cut off the power supply and controls the high-voltage cascaded energy storage device to supply power to the load.

[0011] In some embodiments, a detection module connected to the controller is further included; the detection module is used to detect the grid voltage and current signals; wherein the controller is used to receive feedback signals from the detection module and determine whether a voltage dip occurs in the grid based on the feedback signals.

[0012] In some embodiments, the detection module is further configured to detect the voltage of the high-voltage cascaded energy storage device; wherein the controller is configured to receive the voltage of the high-voltage cascaded energy storage device and control the high-voltage cascaded energy storage device to stop supplying power when the voltage is lower than a preset voltage threshold.

[0013] In some embodiments, a control switch is provided at one end of the line connecting the high-voltage cascaded energy storage device to the switch module and the load. The control switch is used to control whether the high-voltage cascaded energy storage device is locked. When the high-voltage cascaded energy storage device stops supplying power and the power grid has not yet returned to normal, the control switch is opened to lock the high-voltage cascaded energy storage device.

[0014] In some embodiments, the controller is further configured to receive the sensitivity of the load-side sensitive load and set the response time of the management device according to the sensitivity of the load-side sensitive load, so as to ensure that the power supply mode switching is completed within the load protection operation time.

[0015] In some embodiments, the switching module includes a thyristor electronic switch with a fast switching function.

[0016] In some embodiments, the converter module includes a DC / AC bidirectional converter; the converter module is connected to the energy storage element via a DC / DC circuit for controlling the charging and discharging of the energy storage element.

[0017] In some embodiments, the treatment device further includes a bypass switch; the bypass switch is connected in parallel across the two ends of the switch module.

[0018] Secondly, this disclosure provides a voltage sag mitigation method, implemented based on the aforementioned mitigation device, the method comprising the following steps:

[0019] The operating state of the high-voltage cascaded energy storage device is determined based on the voltage of the high-voltage cascaded energy storage device and the grid voltage; the operating state includes voltage sag mitigation state;

[0020] When a voltage sag occurs in the power grid, the switching module is controlled to shut down to disconnect the load from the power grid, and the high-voltage cascaded energy storage device is controlled to enter a voltage sag mitigation state so as to supply power to the load using the high-voltage cascaded energy storage device.

[0021] In some embodiments, controlling the high-voltage cascaded energy storage device to enter a voltage sag mitigation state includes:

[0022] The voltage signal of the power grid at the instant the switching module is turned off is obtained, and the voltage signal includes voltage amplitude and phase;

[0023] The output voltage of the high-voltage cascaded energy storage device entering the voltage sag management state is determined based on the voltage signal of the power grid at the moment the switching module is turned off, so as to use the output voltage to control the high-voltage cascaded energy storage device to supply power to the load.

[0024] In some embodiments, the governance method further includes:

[0025] Obtain the sensitivity of the load at the load end;

[0026] The response time of the governance device is set according to the sensitivity of the load-sensitive load to ensure that the power supply switching action from the power grid to the high-voltage cascaded energy storage device is completed within the load protection action time.

[0027] In some embodiments, the governance method further includes:

[0028] Obtain the voltage of the energy storage element when the high-voltage cascaded energy storage device supplies power to the load;

[0029] When the voltage of the energy storage element is lower than a preset voltage threshold, the high-voltage cascaded energy storage device is controlled to stop supplying power, and it is determined whether the grid voltage has returned to normal.

[0030] If so, the switch module is turned on to switch to power supply from the grid to the load, and the high-voltage cascaded energy storage device is switched to charging state.

[0031] If not, the high-voltage cascaded energy storage device is locked to stop supplying power to the load, so that the load shuts down and waits for the grid to be restored.

[0032] Thirdly, this disclosure provides an electronic device including a memory, a processor, and a computer program stored in the memory, wherein the processor executes the computer program to implement the steps of the method described in the preceding aspects.

[0033] Fourthly, this disclosure provides a computer-readable storage medium having a computer program stored thereon that, when executed by a processor, implements the steps of the methods described in the above aspects.

[0034] Fifthly, this disclosure provides a computer program product, including a computer program that, when executed by a processor, implements the steps of the methods described in the above aspects.

[0035] Compared with the prior art, the present invention has the following advantages and beneficial effects:

[0036] This disclosure provides a voltage sag mitigation device and method. The device includes a switch module connected in series between the power grid and the load; a high-voltage cascaded energy storage device connected to the line between the switch module and the load; the high-voltage cascaded energy storage device includes several converter modules connected in series and energy storage elements connected to each converter module; and a controller connected to the switch module and the high-voltage cascaded energy storage device. When a voltage sag occurs in the power grid, the controller controls the switch module to cut off the power supply and controls the high-voltage cascaded energy storage device to supply power to the load. By using a high-voltage cascaded energy storage device, the converter modules connected to energy storage elements are connected in series, allowing them to be directly connected to the medium- and high-voltage power grid side without the need for transformers. This reduces investment costs and the complexity of the mitigation equipment, enabling unified and centralized mitigation of voltage sags in the medium- and high-voltage power grid. This effectively reduces the impact of voltage sag faults in the medium- and high-voltage transmission and distribution network on the load, effectively improving power supply stability, reducing losses caused by sensitive load outages, and simultaneously reducing the number of voltage sag mitigation devices and maintenance workload. Furthermore, by combining thyristor electronic switches and converter modules, coordinated control between the two is achieved. Utilizing the rapid switching characteristics of the electronic switches, the voltage sag fault clearing time is reduced to less than 10ms, quickly switching to energy storage converter power supply. The energy storage converter then provides a stable voltage to the load, effectively reducing the impact of voltage sags on sensitive loads. Simultaneously, during voltage sags, the load is powered by the energy storage converter, which is unaffected by grid voltage sags and can mitigate various types of voltage sags, overcoming the limitations of electronic switch mitigation. Finally, by setting a mitigation response time, the power supply mode switching is ensured to complete within the load protection operation time, guaranteeing the safe operation of sensitive loads and improving operational safety. Attached Figure Description

[0037] The present disclosure will be described in more detail below based on embodiments and with reference to the accompanying drawings:

[0038] Figure 1 An exemplary circuit diagram of a voltage sag control device provided in this disclosure embodiment;

[0039] Figure 2 An exemplary flowchart of a voltage sag mitigation method provided in an embodiment of this disclosure;

[0040] Figure 3A further exemplary flowchart of the voltage sag mitigation method provided in the embodiments of this disclosure;

[0041] Figure 4 For the embodiments of this disclosure, corresponding to Figure 2 An exemplary flowchart of step S2;

[0042] Figure 5 A further exemplary flowchart of the voltage sag mitigation method provided in this disclosure when powered by a high-voltage cascaded energy storage device;

[0043] Figure 6 This is a schematic block diagram of an electronic device provided in an embodiment of this disclosure;

[0044] Figure 7 This is a schematic diagram of a computer-readable storage medium provided in an embodiment of this disclosure.

[0045] In the accompanying drawings, the same parts are referred to by the same reference numerals, and the drawings are not drawn to scale.

[0046] In the diagram, 1 is the switch module; 2 is the bypass switch; 3 is the controller; and 4 is the high-voltage cascaded energy storage device. Detailed Implementation

[0047] To enable those skilled in the art to better understand the technical solutions of this disclosure, and to fully understand and implement the process of how this disclosure applies technical means to solve technical problems and achieve corresponding technical effects, the technical solutions in the embodiments of this disclosure will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this disclosure, not all embodiments. The embodiments of this disclosure and the various features within them can be combined with each other without conflict, and the resulting technical solutions are all within the protection scope of this disclosure. All other embodiments obtained by those skilled in the art based on the embodiments of this disclosure without creative effort should fall within the protection scope of this disclosure.

[0048] It should be noted that the terms "first," "second," etc., in the specification, claims, and accompanying drawings of this disclosure are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that such data can be interchanged where appropriate so that the embodiments of this disclosure described herein can be implemented in orders other than those illustrated or described herein. Furthermore, the terms "comprising" and "having," and any variations thereof, are intended to cover non-exclusive inclusion; for example, a process, method, system, product, or apparatus that comprises a series of steps or units is not necessarily limited to those steps or units explicitly listed, but may include other steps or units not explicitly listed or inherent to such processes, methods, products, or apparatus.

[0049] It should be noted that the steps shown in the flowchart in the accompanying drawings can be executed in a computer system such as a set of computer-executable instructions, and although a logical order is shown in the flowchart, in some cases the steps shown or described may be executed in a different order than that shown here.

[0050] With the rapid development of the modern power industry and the increasing proportion of power electronic equipment and precision electronic equipment in the power load of the system, voltage sags have an increasingly significant impact on power users. During power transmission and use, grid faults such as short-circuit faults, overload faults, and poor contact, as well as sudden load changes such as the starting of large motors, and natural disasters such as lightning and storms, can all cause voltage sags. Voltage sags can cause grid instability; prolonged voltage sags can prevent motors and other loads from operating normally, and in severe cases, can lead to load damage. Furthermore, voltage sags can cause malfunctions or damage to precision equipment such as power electronics, leading to production interruptions and significant economic losses. Specifically, a voltage sag refers to a temporary drop in the effective value of the power frequency voltage at a point in the power system to 10%–90% of the rated voltage (i.e., an amplitude of 0.1–0.9 (pu)), lasting for 10 ms–1 minute, during which the system frequency remains at the nominal value, before returning to the normal level.

[0051] To mitigate voltage sags and improve grid stability, voltage sag mitigation devices need to be installed at the grid or load points. Currently, most voltage sag mitigation devices are low-voltage equipment applied at the load end, mitigating voltage sags on a specific load basis. This results in a large number of devices, a lack of coordinated control between them, and an inability to manage voltage sags in medium- and high-voltage systems.

[0052] This disclosure provides a voltage sag mitigation device, comprising: a switch module connected in series between the power grid and the load; a high-voltage cascaded energy storage device connected to the line between the switch module and the load; the high-voltage cascaded energy storage device comprising a plurality of converter modules connected in series and energy storage elements connected one-to-one with each converter module; and a controller connected to the switch module and the high-voltage cascaded energy storage device; wherein, when a voltage sag occurs in the power grid, the controller controls the switch module to cut off the power supply and controls the high-voltage cascaded energy storage device to supply power to the load. By employing a high-voltage cascaded energy storage device, the converter modules connected with energy storage elements are connected in series, allowing them to be directly connected to the medium- and high-voltage power grid side without the need for transformers, reducing investment costs and the complexity of mitigation equipment. This enables unified and centralized mitigation of voltage sags in the medium- and high-voltage power grid, effectively reducing the impact of voltage sag faults in the medium- and high-voltage transmission and distribution network on the load, effectively improving power supply stability, reducing losses caused by the shutdown of sensitive loads, and simultaneously reducing the number of voltage sag mitigation devices and maintenance workload.

[0053] Example 1

[0054] Figure 1 This is an exemplary connection diagram of a voltage sag mitigation device provided in an embodiment of this disclosure. Figure 1 As shown, a voltage sag mitigation device includes a switching module 1, a high-voltage cascaded energy storage device 4, a controller 3, a bypass switch 2, and a detection module; wherein, the switching module 1 is connected in series between the power grid and the load, and the power grid is... Figure 1 The system power supply is as follows: a bypass switch 2 is connected in parallel across the two ends of the switch module 1; a high-voltage cascaded energy storage device 4 is connected to the line between the switch module 1 and the load; a controller 3 is connected to the switch module 1 and the high-voltage cascaded energy storage device 4, and is used to control the switch module 1 to cut off the power supply and control the high-voltage cascaded energy storage device 4 to supply power to the load when a voltage dip occurs in the power grid; the two ends of the detection module are respectively connected to the controller 3 and the line between the switch module 1 and the load, and are used to detect the voltage signal of the power grid and send it to the controller 3, so that the controller 3 can determine whether a voltage dip has occurred in the power grid through the feedback signal.

[0055] Furthermore, the high-voltage cascaded energy storage device 4 includes several converter modules connected in series and energy storage elements connected one-to-one with each converter module. By adopting a high-voltage cascaded topology, the high-voltage cascaded energy storage device 4 can be directly connected to the medium- and high-voltage power grid for use, and there is no need to configure a step-up transformer. The energy storage capacity of the energy storage device can be adjusted by adjusting the energy storage elements configured in the converter modules, thereby reducing the investment cost of large-capacity devices.

[0056] The number of converter modules is adjusted according to the voltage level of the power grid to adapt to the voltage changes of the current power grid output, thereby providing a smooth and stable voltage switching when performing voltage sag mitigation and avoiding sudden voltage changes at the load end.

[0057] Furthermore, the converter modules in the high-voltage cascaded energy storage device 4 can be connected in a delta configuration, which can help manage the three-phase imbalance of the power grid and improve the management effect.

[0058] Among them, the high-voltage cascaded energy storage device 4 adjusts its output current and power by switching its own control mode, thereby mitigating grid harmonics, compensating reactive power, comprehensively improving power quality, and enhancing the stability of load-side operation to a certain extent.

[0059] In some embodiments, the converter module includes a DC / AC bidirectional converter; the converter module is connected to the energy storage element via a DC / DC circuit for controlling the charging and discharging of the energy storage element, so as to control the charging and discharging process of the energy storage element, realize the AC-DC conversion, and supply power to AC loads in the absence of grid power.

[0060] In some embodiments, the switching module 1 includes a thyristor electronic switch with fast switching function, wherein the thyristor electronic switch and the high-voltage cascaded energy storage device 4 are combined to enable the two to perform coordinated control. By utilizing the fast switching characteristics of the electronic switch, the voltage sag fault clearing time is reduced to less than 10ms, and the power supply is quickly switched to the high-voltage cascaded energy storage device 4. The high-voltage cascaded energy storage device 4 provides a stable voltage to the load, effectively reducing the impact of voltage sag on sensitive loads and reducing losses caused by abnormal shutdowns. Furthermore, the high-voltage cascaded energy storage device 4 is not affected by grid voltage sag and can manage various types of voltage sags, thus overcoming the limitations of electronic switch management.

[0061] In some embodiments, the bypass switch 2 is a mechanical switch, which may be any one of a circuit breaker, contactor, or load switch, and may be used as a backup switch when the switch module 1 fails or is under maintenance.

[0062] In some embodiments, the detection module is further configured to detect the voltage of the high-voltage cascaded energy storage device 4; wherein, the controller 3 is configured to receive the voltage of the high-voltage cascaded energy storage device 4, and control the high-voltage cascaded energy storage device 4 to stop supplying power when the voltage is lower than a preset voltage threshold, thereby avoiding the impact of low-voltage power supply on load operation stability. When the high-voltage cascaded energy storage device 4 is controlled to stop supplying power, it is determined whether the grid voltage has returned to normal. If it has returned to normal, the switch module 1 is controlled to turn on to switch to power supply from the grid to the load, and the high-voltage cascaded energy storage device 4 is controlled to switch to charging state; if it has not returned to normal, the high-voltage cascaded energy storage device 4 is controlled to lock out to stop supplying power to the load, causing the load to shut down and wait for the grid to recover.

[0063] Specifically, the detection module includes a first detection circuit for detecting the grid voltage and a second detection circuit for detecting the load input current, thereby facilitating the acquisition of grid voltage and load current so that the controller 3 can perform corresponding control based on the acquired voltage signals. Furthermore, to facilitate the acquisition of the voltage of the energy storage elements in the high-voltage cascaded energy storage device 4, the detection module also includes several fourth detection circuits, each corresponding to one of the energy storage elements. The other end of each fourth detection circuit is connected to the controller to feed back the acquired voltage of the energy storage elements to the controller 3.

[0064] Furthermore, a control switch, namely a QF switch, is provided at one end of the line connecting the high-voltage cascaded energy storage device 4 to the switch module 1 and the load. The control switch is used to control whether the high-voltage cascaded energy storage device 4 is locked. Specifically, when the voltage of the energy storage element of the high-voltage cascaded energy storage device 4 is lower than the limit value and the power grid has not yet returned to normal, the control switch is opened to lock the high-voltage cascaded energy storage device 4, thereby cutting off the connection between the high-voltage cascaded energy storage device 4 and the load, and avoiding safety hazards caused by unstable load operation.

[0065] In some embodiments, the controller 3 in the voltage sag mitigation device is further configured to receive the sensitivity of the load-side sensitive load and set the response time of the mitigation device according to the sensitivity of the load-side sensitive load, so as to ensure that the power supply mode switching is completed within the load protection operation time, thereby ensuring that the load-side sensitive load can operate safely and improving the stability of power supply switching during voltage sag.

[0066] The voltage sag mitigation device provided in this embodiment operates as follows: When the power grid is running normally, the switch module 1 is turned on, supplying power to the load through the grid. At this time, the control switch on the high-voltage cascaded energy storage device 4 is closed, and the high-voltage cascaded energy storage device 4 is in standby mode. The power grid charges the energy storage elements in the high-voltage cascaded energy storage device 4. Simultaneously, the controller 3 uses a detection module to collect real-time signals such as voltage and current from the power grid, recording information such as amplitude, phase, and frequency.

[0067] When controller 3 detects a voltage dip in the power grid, it shuts off control switch module 1, disconnecting the load from the grid. Simultaneously, it controls the high-voltage cascaded energy storage device 4 to enter voltage dip mitigation mode, supplying power to the load and forming a microgrid power supply system. Controller 3 records the phase and frequency of the grid voltage at the moment of switching and ensures that the high-voltage cascaded energy storage device 4 inherits the phase and frequency of the grid voltage during switching, guaranteeing a smooth and stable switch and preventing sudden changes in load-side voltage.

[0068] During the power supply process of the high-voltage cascaded energy storage device 4, the voltage of the energy storage element is continuously monitored. When the voltage is lower than the set value, the high-voltage cascaded energy storage device 4 is controlled to stop supplying power. If the grid voltage does not return to normal at this time, the high-voltage cascaded energy storage device 4 is locked and stops supplying power to the load. The load stops and waits for the grid to recover.

[0069] If the voltage of the energy storage element does not reach the lockout setting value, and the controller 3 detects that the grid voltage has returned to normal, it sends a conduction signal to the switch module 1 to control its conduction, allowing the grid to supply power. At the same time, the controller 3 sends a control signal to the high-voltage cascaded energy storage device 4, causing the grid to charge the energy storage element through the converter module. After charging is completed, the converter enters standby mode again, waiting for the next operation.

[0070] By employing a high-voltage cascaded energy storage device, various converter modules connected to energy storage elements are connected in series, allowing them to be directly connected to the medium- and high-voltage power grid side without the need for transformers. This reduces investment costs and the complexity of management equipment, enabling unified and centralized management of voltage sags in the medium- and high-voltage power grid. This effectively reduces the impact of voltage sag faults on loads in the medium- and high-voltage transmission and distribution network, significantly improving power supply stability, reducing losses caused by sensitive load outages, and decreasing the number of voltage sag management devices and maintenance workload. Furthermore, by combining thyristor electronic switches and converter modules, coordinated control is achieved. Utilizing the rapid switching characteristics of electronic switches, the voltage sag fault clearing time is reduced to less than 10ms, quickly switching to energy storage converter power supply. The energy storage converter then provides a stable voltage to the load, effectively reducing the impact of voltage sags on sensitive loads. Simultaneously, during voltage sags, the load is powered by the energy storage converter, which is unaffected by grid voltage sags. This allows for the management of various types of voltage sags, overcoming the limitations of electronic switch management. Finally, by setting a governance response time, the power supply mode switching is ensured to be completed within the load protection action time, thus guaranteeing the safe operation of sensitive loads and improving safety in use.

[0071] Example 2

[0072] Based on the above embodiments, this embodiment provides a voltage sag mitigation method, which is implemented based on the mitigation device described in Embodiment 1, such as... Figure 2 As shown, the treatment method includes the following steps:

[0073] S1. Determine the operating state of the high-voltage cascaded energy storage device based on the voltage of the high-voltage cascaded energy storage device and the grid voltage; the operating state includes voltage sag mitigation state.

[0074] S2. When a voltage sag occurs in the power grid, the switch module is controlled to turn off so that the load is disconnected from the power grid, and the high-voltage cascaded energy storage device is controlled to enter the voltage sag mitigation state so as to use the high-voltage cascaded energy storage device to supply power to the load.

[0075] In this embodiment, the high-voltage cascaded energy storage device operates in three states: voltage sag mitigation, charging, and standby. The charging state occurs when the power grid is operating normally; the grid charges the energy storage element through the converter module. After charging is complete, the high-voltage cascaded energy storage device switches to standby mode, awaiting the next operation.

[0076] In some embodiments, before step S1, such as Figure 3 As shown, the treatment method also includes:

[0077] S101. Obtain the sensitivity of the load at the load end;

[0078] S102. Set the response time of the governance device according to the sensitivity of the load-sensitive load to ensure that the power supply switching action from the power grid to the high-voltage cascaded energy storage device is completed within the load protection action time.

[0079] Specifically, by analyzing the sensitivity of the sensitive load at the load end, the protection action time of the sensitive load can be obtained, and the response time of the set control device can be set within the protection action time, that is, the response time should be less than the protection action time.

[0080] By determining the response time of the control device, when a voltage dip occurs, the control device can complete the power supply switching action from the power grid to the high-voltage cascaded energy storage device within the load protection operation time, thereby ensuring the safe operation of sensitive loads and improving the stability of load-side operation.

[0081] In some embodiments, such as Figure 4 As shown, step S2, controlling the high-voltage cascaded energy storage device to enter the voltage sag mitigation state, includes:

[0082] S21. Obtain the voltage signal of the power grid at the instant the switching module is turned off, the voltage signal including voltage amplitude and phase;

[0083] S22. Determine the output voltage of the high-voltage cascaded energy storage device when it enters the voltage sag management state based on the voltage signal of the power grid at the moment the switch module is turned off, so as to use the output voltage to control the high-voltage cascaded energy storage device to supply power to the load.

[0084] By recording information such as the phase and frequency of the grid voltage at the moment of switching, the converter module inherits the phase and frequency of the grid voltage at the time of switching, thereby ensuring a smooth and stable switching, avoiding sudden changes in the load-side voltage, and improving the stability of the load-side operation.

[0085] In some embodiments, such as Figure 5 As shown, the treatment method also includes:

[0086] S3. Obtain the voltage of the energy storage element when the high-voltage cascaded energy storage device supplies power to the load;

[0087] S4. Determine whether the voltage of the energy storage element is lower than a preset voltage threshold.

[0088] S5. When the voltage of the energy storage element is lower than the preset voltage threshold, control the high-voltage cascaded energy storage device to stop supplying power, and determine whether the grid voltage has returned to normal.

[0089] If so, the switch module is turned on to switch to power supply from the grid to the load, and the high-voltage cascaded energy storage device is switched to charging state. When the high-voltage cascaded energy storage device is fully charged, it switches to standby state to wait for the next action.

[0090] If not, the high-voltage cascaded energy storage device is locked to stop supplying power to the load, causing the load to shut down and wait for the grid to be restored.

[0091] By analyzing the voltage of the energy storage components, the stability of the high-voltage cascaded energy storage device when supplying power to the load can be guaranteed. When the supply voltage is lower than the preset voltage threshold, it is analyzed whether the power grid has recovered. If it has not recovered, the power supply to the load is stopped, and the load is shut down to wait for the power grid to recover, protecting the load-side equipment from the influence of voltage fluctuations and ensuring its service life. If the power grid recovers, it switches to the power grid for stable power supply, so that the load-side continues to operate stably.

[0092] The voltage sag mitigation method provided in this embodiment uses a high-voltage cascaded energy storage device directly connected to the power supply circuit of the power grid. When a voltage sag occurs, the high-voltage cascaded energy storage device performs a smooth and stable power supply switch, realizing unified and centralized management of voltage sags in the power grid. This effectively reduces the impact of voltage sag faults in medium and high voltage transmission and distribution networks on loads, effectively improves power supply stability, reduces losses caused by the shutdown of sensitive loads, and reduces the number of voltage sag mitigation devices and maintenance workload.

[0093] Example 3

[0094] Based on the above embodiments, this embodiment provides a computer device, such as... Figure 6 As shown, the system includes a memory 21, a processor 22, and a computer program stored on the memory 21. The processor 22 executes the computer program to implement the steps of the method described in the above embodiments.

[0095] In some embodiments of this example, a computer-readable storage medium is provided, such as... Figure 7 As shown, a computer program 31 is stored thereon, which, when executed by a processor, implements the steps of the method described in the above embodiments.

[0096] In some embodiments of this example, a computer program product is provided, including a computer program that, when executed by a processor, implements the steps of the method described in the above embodiments.

[0097] The processor may include, but is not limited to, one or more processors or microprocessors. Each processor may be implemented as an Application Specific Integrated Circuit (ASIC), Digital Signal Processor (DSP), Digital Signal Processing Device (DSPD), Programmable Logic Device (PLD), Field Programmable Gate Array (FPGA), controller, microcontroller, microprocessor, or other electronic component, for executing the methods described in the above embodiments.

[0098] Computer-readable storage media can be implemented by any type of volatile or non-volatile storage device or a combination thereof. Computer-readable storage media may include, but are not limited to, random access memory (RAM), read-only memory (ROM), flash memory, EPROM memory, EEPROM memory, registers, and computer storage media (e.g., hard disks, floppy disks, solid-state drives, removable disks, CD-ROMs, DVD-ROMs, Blu-ray discs, etc.).

[0099] Computer-readable storage media may also store at least one computer-executable program / instruction, such as computer-readable instructions. Computer-readable storage media include, but are not limited to, volatile memory and / or non-volatile memory. Volatile memory may include, for example, random access memory (RAM) and / or cache memory. Computer-readable storage media may include, for example, read-only memory (ROM), hard disk, flash memory, etc. For example, a non-transitory computer-readable storage medium may be connected to a computing device such as a computer, and then, when the computing device executes the computer-readable instructions stored on the computer-readable storage medium, the various methods described above can be performed.

[0100] In addition, the computer device may include (but is not limited to) a data bus, an input / output (I / O) bus, a display, and input / output devices (e.g., keyboard, mouse, speakers, etc.).

[0101] The processor can communicate with external devices via the I / O bus through wired or wireless networks.

[0102] In one embodiment, the at least one computer-executable instruction may also be compiled into or comprise a software product / computer program product, wherein one or more computer-executable instructions are executed by a processor to perform the steps of the various functions and / or methods in the embodiments described herein.

[0103] In the embodiments provided in this disclosure, it should be understood that the disclosed apparatus and methods can also be implemented in other ways. The apparatus embodiments described above are merely illustrative; for example, the flowcharts and block diagrams in the accompanying drawings illustrate the architecture, functionality, and operation of possible implementations of apparatus, methods, and computer program products according to various embodiments of this disclosure. In this regard, each block in a flowchart or block diagram may represent a module, segment, or portion of code containing one or more executable instructions for implementing a specified logical function. It should also be noted that in some alternative implementations, the functions marked in the blocks may occur in a different order than those marked in the drawings. For example, two consecutive blocks may actually be executed substantially in parallel, and they may sometimes be executed in reverse order, depending on the functions involved. It should also be noted that each block in a block diagram and / or flowchart, and combinations of blocks in block diagrams and / or flowcharts, can be implemented using a dedicated hardware-based system that performs the specified function or action, or using a combination of dedicated hardware and computer instructions.

[0104] It should be noted that, in this disclosure, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitation, an element limited by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes that element.

[0105] While the embodiments disclosed herein are as described above, the foregoing content is merely for the purpose of facilitating understanding of this disclosure and is not intended to limit this disclosure. Any person skilled in the art to which this disclosure pertains may make any modifications and changes in form and detail of the implementation without departing from the spirit and scope of this disclosure; however, the scope of patent protection of this disclosure shall still be determined by the scope defined in the appended claims.

Claims

1. A voltage sag mitigation device, applied in a circuit between the power grid and the load, characterized in that, include: A switching module connected in series between the power grid and the load; A high-voltage cascaded energy storage device is connected to the line between the switch module and the load; the high-voltage cascaded energy storage device includes several converter modules connected in series and energy storage elements connected one-to-one with each converter module. And a controller connected to the switch module and the high-voltage cascaded energy storage device; When a voltage dip occurs in the power grid, the controller controls the switching module to cut off the power supply and controls the high-voltage cascaded energy storage device to supply power to the load.

2. The voltage sag control device according to claim 1, characterized in that, It also includes a detection module connected to the controller; the detection module is used to detect the voltage and current signals of the power grid; wherein, the controller is used to receive the feedback signal from the detection module and determine whether the power grid is experiencing a voltage dip based on the feedback signal.

3. The voltage sag control device according to claim 2, characterized in that, The detection module is also used to detect the voltage of the high-voltage cascaded energy storage device; wherein, the controller is used to receive the voltage of the high-voltage cascaded energy storage device, and control the high-voltage cascaded energy storage device to stop supplying power when the voltage is lower than a preset voltage threshold.

4. A voltage sag mitigation device according to claim 1 or 3, characterized in that, A control switch is provided at one end of the line connecting the high-voltage cascaded energy storage device to the switch module and the load. The control switch is used to control whether the high-voltage cascaded energy storage device is locked. When the high-voltage cascaded energy storage device stops supplying power and the power grid has not yet returned to normal, the control switch is opened to lock the high-voltage cascaded energy storage device.

5. The voltage sag control device according to claim 1, characterized in that, The controller is also used to receive the sensitivity of the load-sensitive load and set the response time of the control device according to the sensitivity of the load-sensitive load to ensure that the power supply mode is switched within the load protection operation time.

6. The voltage sag control device according to claim 1, characterized in that, The switching module includes a thyristor electronic switch with a fast switching function.

7. The voltage sag control device according to claim 1, characterized in that, The converter module includes a DC / AC bidirectional converter; the converter module is connected to the energy storage element via a DC / DC circuit for controlling the charging and discharging of the energy storage element.

8. The voltage sag control device according to claim 1, characterized in that, The treatment device also includes a bypass switch; the bypass switch is connected in parallel across both ends of the switch module.

9. A method for controlling voltage sags, implemented based on the control device according to any one of claims 1-8, characterized in that, The governance method includes the following steps: The operating status of the high-voltage cascaded energy storage device is determined based on the voltage of the device and the grid voltage; the operating status includes voltage sag mitigation status. When a voltage sag occurs in the power grid, the switching module is controlled to shut down to disconnect the load from the power grid, and the high-voltage cascaded energy storage device is controlled to enter a voltage sag mitigation state so as to supply power to the load using the high-voltage cascaded energy storage device.

10. A voltage sag mitigation method according to claim 9, characterized in that, The control of the high-voltage cascaded energy storage device to enter the voltage sag mitigation state includes: The voltage signal of the power grid at the instant the switching module is turned off is obtained, and the voltage signal includes voltage amplitude and phase; The output voltage of the high-voltage cascaded energy storage device entering the voltage sag management state is determined based on the voltage signal of the power grid at the moment the switching module is turned off, so as to use the output voltage to control the high-voltage cascaded energy storage device to supply power to the load.

11. A voltage sag mitigation method according to claim 9, characterized in that, The governance method further includes: obtaining the sensitivity of the sensitive load at the load end; The response time of the governance device is set according to the sensitivity of the load-sensitive load to ensure that the power supply switching action from the power grid to the high-voltage cascaded energy storage device is completed within the load protection action time.

12. A voltage sag mitigation method according to claim 9, characterized in that, The governance method further includes: obtaining the voltage of the energy storage element when the high-voltage cascaded energy storage device supplies power to the load; When the voltage of the energy storage element is lower than a preset voltage threshold, the high-voltage cascaded energy storage device is controlled to stop supplying power, and it is determined whether the grid voltage has returned to normal. If so, the switch module is turned on to switch to power supply from the grid to the load, and the high-voltage cascaded energy storage device is switched to charging state. If not, the high-voltage cascaded energy storage device is locked to stop supplying power to the load, causing the load to shut down and wait for the grid to be restored.

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