Low-voltage power distribution network full-chain cascade management method and system based on pressure pump device

Abstract

The application provides a low-voltage power distribution network full-chain cascade management method and system based on a pressure pump device, and relates to the technical field of voltage management. By constructing a full-chain cascade management mode, the pressure pump device is deployed at each key link of the low-voltage power distribution network. When a large range of voltage out-of-limit occurs, the first-end pressure pump device is preferentially started for global adjustment, thereby avoiding excessive frequent operation of the end device. When the problem is limited to a specific area, the middle-end pressure pump device is used for accurate adjustment, thereby avoiding the side effects that may be caused by global adjustment. For the voltage problem of an individual user, the end pressure pump device is used for final compensation. The method effectively avoids the negative effects that may be caused by single-link adjustment, realizes the pertinence and effectiveness of voltage management, and significantly improves the voltage quality and operation stability of the low-voltage power distribution network.

Description

Technical Field

[0001] This invention relates to the field of voltage management technology, and more specifically, to a method and system for cascaded management of the entire low-voltage distribution network based on a pressure pump device. Background Technology

[0002] In the operation of low-voltage distribution networks, voltage regulation is necessary. Existing methods use voltage-regulating distribution transformers for voltage regulation within the distribution area. The working principle is as follows: the controller monitors the low-voltage output voltage of the transformer in real time. When the voltage deviates from a set threshold, the drive motor moves the tap changer contacts to switch the high-voltage side taps of the transformer, changing the turns ratio and thus adjusting the output voltage to the acceptable range. However, this mechanical voltage regulation at the distribution area level cannot achieve continuous and smooth voltage regulation, and is prone to under-regulation or over-regulation, especially when there is a large amount of distributed photovoltaic power generation or impulsive load connection, making precise dynamic tracking impossible.

[0003] In addition, most existing products are independent devices designed for a single link, such as the beginning or end, and regulate voltage at a single link. When power quality problems occur, such as voltage exceeding the limit, blindly raising the voltage at the beginning may cause the voltage at the end to exceed the limit. If the end is compensated separately, it may cause circulating current or resonance with the middle section of the line. The treatment of a single link cannot fundamentally solve the problem. The treatment measures lack specificity and are not effective. Summary of the Invention

[0004] The problem that this invention aims to solve is that existing voltage control methods that involve setting up a distribution transformer in a single stage lack specificity and have poor control effects.

[0005] To address the aforementioned problems, in a first aspect, this invention provides a cascaded management method for the entire low-voltage distribution network based on a pressure pump device. Pressure pump devices are installed at the beginning, middle, and end of the low-voltage distribution network. The beginning pressure pump device is connected to the low-voltage side of the transformer substation to regulate the overall voltage. The middle pressure pump device is connected in series to a branch line of the low-voltage distribution network to regulate the corresponding area voltage. The end pressure pump device is connected in series to the incoming line side of a single-phase user to regulate the incoming voltage. The pressure pump devices are used to manage voltage boosting or bucking. The method includes: Real-time collection of voltage data at various nodes in the low-voltage distribution network, including transformer substation nodes, branch nodes, and household access nodes; Compare the voltage at each node with the corresponding rated value to determine the status of each node, which includes low voltage over-limit, normal, and high voltage over-limit. If only one-way limit exceedance exists among all branch nodes, and the proportion of one-way limit exceedance exceeds the first preset ratio, the global adjustment process is triggered to control the operation of the head pump device. If there are bidirectional over-limits in all branch nodes, or the proportion of unidirectional over-limits is lower than the first preset ratio, or there are still areas with voltage over-limits after global adjustment, the multi-area collaborative adjustment process is triggered to control the operation of the mid-end pressure pump device in multiple areas. If, after adjustment by the first-end pump and the middle-end pump, the voltage at the inlet node still exceeds the limit, then the end pump at that inlet node will be controlled to operate.

[0006] Secondly, the present invention also provides a low-voltage distribution network full-chain cascaded management system based on a pressure pump device, wherein pressure pump devices are installed at the beginning, middle and end of the low-voltage distribution network; the pressure pump device at the beginning is connected to the low-voltage side of the transformer in the distribution area and is used to regulate the global voltage; the pressure pump device at the middle is connected in series to the branch line of the low-voltage distribution network and is used to regulate the area voltage of the corresponding area; the pressure pump device at the end is connected in series to the incoming line side of a single-phase user and is used to regulate the incoming voltage; the pressure pump device is used to manage voltage boosting or bucking. The system includes: The data acquisition module is used to collect voltage data at various nodes of the low-voltage distribution network in real time. These nodes include transformer substation nodes, branch nodes, and service access nodes. The node analysis module is used to compare the voltage at each node with the corresponding rated value to determine the status of each node, including low voltage over-limit, normal and high voltage over-limit. The head-end controller is used to trigger a global adjustment process and control the head-end pressure pump device to work if there is only one-way over-limit in all branch nodes and the proportion of one-way over-limit exceeds the first preset ratio. The mid-range controller is used to trigger a multi-region collaborative adjustment process and control the operation of the mid-range pressure pump device in multiple regions if there are bidirectional over-limits in all branch nodes, or the proportion of unidirectional over-limits is lower than the first preset ratio, or there are still areas with voltage over-limits after global adjustment. The end controller is used to control the end pump device at the household node to operate if the voltage exceeds the limit at the household node after adjustment by the first-end pump device and the middle-end pump device.

[0007] This invention provides a method and system for the full-chain cascaded management of low-voltage power distribution networks based on a pressure pump device. Compared with existing technologies, it has the following advantages: By constructing a cascaded governance model across the entire chain, voltage booster devices are deployed at various key links in the low-voltage distribution network, and a three-tiered regulation process—global, regional, and end-point—is designed. This hierarchical and collaborative governance approach can select the most appropriate regulation level for intervention based on the scope and nature of voltage exceedances. When a large-scale voltage exceedance occurs, the first-level voltage booster devices are activated first for global regulation, avoiding excessively frequent actions by end-point devices. When the problem is limited to a specific area, the intermediate-level voltage booster devices perform precise regulation, avoiding potential side effects from global regulation. For voltage issues affecting individual users, the end-point voltage booster devices provide final compensation. Therefore, this method effectively avoids the negative impacts that may result from regulation at a single point, achieving targeted and effective voltage governance, and significantly improving the voltage quality and operational stability of the low-voltage distribution network. Attached Figure Description

[0008] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0009] Figure 1 A schematic diagram of a low-voltage distribution network line structure provided in an embodiment of the present invention; Figure 2 A flowchart illustrating a cascaded governance method for the entire low-voltage distribution network based on a pressure pump device, provided in an embodiment of the present invention; Figure 3 This is a schematic diagram of the first, middle, and last cascaded treatment provided in an embodiment of the present invention; Figure 4 A schematic diagram illustrating the handling of head-end faults provided in an embodiment of the present invention; Figure 5 A schematic diagram illustrating the handling of interruption faults provided in an embodiment of the present invention; Figure 6 A schematic diagram illustrating the management of end-point faults provided in an embodiment of the present invention; Figure 7 A schematic diagram of the structure of a single-stage AC / AC converter circuit provided in an embodiment of the present invention; Figure 8 A schematic diagram of the circuit structure of Example 1 provided in the embodiment of the present invention; Figure 9 A schematic diagram of the circuit structure of Example 2 provided in this embodiment of the invention; Figure 10 A schematic diagram of the circuit structure of Example 3 provided in this embodiment of the invention; Figure 11A schematic diagram of the circuit structure of Example 4 provided in the embodiments of the present invention; Figure 12 A schematic diagram of the circuit structure of Example 5 provided in this embodiment of the invention; Figure 13 This is a schematic diagram of a low-voltage power distribution network full-chain cascaded governance system based on a pressure pump device, provided as an embodiment of the present invention.

[0010] Explanation of reference numerals in the attached figures: 1. Distribution transformer; 2. First-end pressure pump device; 3. Middle-end pressure pump device; 4. End-end pressure pump device. Detailed Implementation

[0011] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, the technical solutions in the embodiments of this application are described clearly and completely. Obviously, the described embodiments are only some embodiments of this application, not all embodiments. Based on the embodiments in this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0012] To better understand the above technical solutions, the following will provide a detailed explanation of the technical solutions in conjunction with the accompanying drawings and specific implementation methods.

[0013] like Figure 1 As shown, pump devices are installed at the beginning, middle and end of the low-voltage distribution network; the beginning pump device 2 is connected to the low-voltage side of the transformer 1 in the distribution area to regulate the overall voltage; the middle pump device 3 is connected in series to the branch line of the low-voltage distribution network to regulate the area voltage of the corresponding area; the end pump device 4 is connected in series to the incoming line side of the single-phase user to regulate the incoming voltage; the pump devices are used to control voltage rise or fall.

[0014] This invention constructs a system architecture of three-stage pressure pump devices cascaded at the transformer head end, branch line middle end, and user end of a low-voltage distribution network. The three-stage devices are interconnected through communication to form a complete voltage management closed loop. The communication can be selected from options such as power line carrier communication, 4G, or 5G.

[0015] A three-phase high-power head-end pump unit is connected to the low-voltage side of the distribution transformer and works in conjunction with existing unloaded voltage regulating transformers in the distribution area. The coordination method involves fixing the transformer tap position while fine-tuning the head-end pump unit. Specifically, the head-end pump unit draws power directly from the low-voltage side of the transformer, and its input voltage is the same as the secondary output voltage of the transformer. This connection method fully utilizes the inherent voltage regulation capability of the transformer, enabling real-time linkage between the pump unit's operating status and voltage fluctuations in the distribution area. This effectively avoids the problem of frequent transformer tap adjustments due to load changes, significantly reduces the frequency of manual intervention, and improves the self-governance level of the distribution area's power supply.

[0016] A three-phase medium-power intermediate-range pressure pump device is connected in series to the middle section of a low-voltage distribution network branch line. The capacity of the intermediate-range pressure pump device is determined according to the load of the branch line. The control strategy is three-phase decoupling control, which can be applied to voltage over-limit situations under three-phase balance as well as three-phase unbalanced scenarios. The three-phase medium-power intermediate-range pressure pump device fills the technical gap of the long-standing lack of voltage management methods in the middle section of branch lines.

[0017] A single-phase low-power end-point pressure pump unit is connected in series to the incoming line side of a single-phase user. The capacity of the end-point pressure pump unit is determined according to the single-phase user's load, and compensation voltage is injected locally to achieve lightweight, highly reliable, and accurate compensation.

[0018] like Figure 2 As shown in the figure, this application provides a method for the full-chain cascaded management of low-voltage distribution networks based on a pump device, including: S1: Real-time collection of voltage data at various nodes in the low-voltage distribution network, including transformer substation nodes, branch nodes, and household access nodes.

[0019] Specifically, each pressure pump unit has a built-in MCU core controller, possessing complete capabilities for acquiring voltage, current, and other signals, performing logical judgments, and controlling them. In the event of communication interruption or failure to establish communication between units, each level of unit operates independently based on its local sampled values. The first-end pressure pump unit uses its output voltage as the control target and independently adjusts to its rated value; the rated value of the first-end pressure pump unit is determined according to the expected output voltage of the transformer in different distribution areas. The intermediate-end pressure pump unit uses the voltage of the node where it is located as the control target and independently adjusts to its rated value; the rated value of the intermediate-end pressure pump unit is determined according to the expected voltage of different nodes. The terminal unit uses the user-side voltage as the control target and independently adjusts to its rated value; the user-side rated value is generally 220V effective AC.

[0020] When the devices maintain normal communication, each level controller can receive the operating status of the devices at the upper and lower levels, including the current output voltage, compensation amount, load current, etc.; receive the operating status of adjacent devices at the same level; and dynamically adjust its own compensation instructions based on global information.

[0021] S2: Compare the voltage at each node with the corresponding rated value to determine the status of each node, including low voltage over-limit, normal, and high voltage over-limit.

[0022] Specifically, such as Figure 3As shown, since low-voltage distribution networks require the transmission voltage to be around 220V, for example, fluctuating by a certain percentage, when the voltage is within this fluctuation range, it is considered to be in a normal state. When it exceeds this fluctuation range, it is considered to be a voltage over-limit. The upper and lower limits of this fluctuation range are recorded as the upper limit and lower limit of the voltage over-limit. If it is below the lower limit, it is a low-voltage over-limit, and if it is above the upper limit, it is a high-voltage over-limit.

[0023] S3: If only unidirectional limit exceedance exists among all branch nodes, and the proportion of unidirectional limit exceedance exceeds the first preset ratio, the global adjustment process is triggered, controlling the operation of the head-end pressure pump device. Unidirectional limit exceedance means that only one of the two states, low voltage node and high voltage node, exists among all branch nodes.

[0024] Specifically, when the central control unit analyzes and finds that all branch nodes experiencing voltage exceedances exhibit low-voltage exceedances, and the number of these low-voltage exceedance nodes accounts for a proportion of the total number of branch nodes exceeding a preset threshold (e.g., 60%), this indicates a potentially widespread low voltage problem across the entire distribution network. In this case, the central control unit sends a command to the head-end voltage booster device, instructing it to uniformly boost the voltage across the entire distribution network, for example, by raising the output voltage by a fixed value.

[0025] S4: If bidirectional over-limit occurs in all branch nodes, or the proportion of unidirectional over-limit is less than the first preset ratio, or if voltage over-limit still exists in some areas after global adjustment, the multi-area coordinated adjustment process is triggered, controlling the operation of the mid-range pressure pump device in multiple areas. Bidirectional over-limit means that both low-voltage and high-voltage states exist simultaneously in all branch nodes.

[0026] For example, if the central control unit detects that there are both low-voltage and high-voltage over-limit nodes in the branch nodes, or that although it is a unidirectional over-limit, its proportion has not reached the threshold for triggering global regulation, this indicates that the voltage problem may not be global, but rather localized. In this case, the central control unit will identify the areas with voltage over-limits and send instructions to the intermediate voltage pump devices in these areas to regulate the voltage in their respective areas.

[0027] S5: If the voltage exceeds the limit at the inlet node after adjustment by the first-end pump device and the middle-end pump device, then control the end pump device at the inlet node to work.

[0028] For example, after adjustments at the global and regional levels, the central control unit collects and analyzes the voltage data of the incoming nodes again. If it finds that the incoming voltage of a certain user is still lower or higher than the normal range, it will send a command to the terminal voltage pump device on the incoming side of that user, which will then perform final, targeted voltage compensation to ensure that the voltage at the user end is qualified.

[0029] In this optional embodiment, a cascaded governance model is constructed, deploying voltage booster devices at various key links of the low-voltage distribution network and designing a three-level regulation process: global, regional, and end-point. This hierarchical and collaborative governance approach can select the most appropriate regulation level for intervention based on the scope and nature of voltage exceedances. For example, when a large-scale voltage exceedance occurs, the first-end voltage booster device is activated first for global regulation, avoiding excessively frequent actions by end-point devices; when the problem is limited to a specific area, the mid-range voltage booster device performs precise regulation, avoiding potential side effects from global regulation; and for voltage problems of individual users, the end-point voltage booster device provides final compensation. Therefore, this method effectively avoids the negative impacts that may result from regulation at a single stage, achieving targeted and effective voltage governance, and significantly improving the voltage quality and operational stability of the low-voltage distribution network.

[0030] The following is a detailed description of each step.

[0031] S1: Real-time collection of voltage data at various nodes in the low-voltage distribution network, including transformer substation nodes, branch nodes, and household access nodes.

[0032] S2: Compare the voltage at each node with the corresponding rated value to determine the status of each node, including low voltage over-limit, normal, and high voltage over-limit.

[0033] S3: If there is only one-way limit violation among all branch nodes, and the proportion of one-way limit violation exceeds the first preset ratio, the global adjustment process is triggered to control the operation of the head pump device.

[0034] Specifically, this applies to situations where a large area of ​​low-voltage power exceeds the limit in the transformer substation.

[0035] If all unidirectional over-limits in all branch nodes are low-pressure over-limits, and the proportion of low-pressure over-limits exceeds a first preset ratio, a global boost regulation process is triggered, controlling the operation of the head-end pressure pump device. The boost regulation process includes: The compensation amount is determined based on the current node voltage and corresponding rated value at the low-voltage over-limit point.

[0036] The compensation amounts are sorted from largest to smallest, and the average value of the compensation amounts at the preset percentage before sorting is calculated to obtain the target boost amplitude. Among them, the weight ratio of faulty nodes is greater than that of normal nodes.

[0037] The maximum pressure margin is obtained based on the current outlet voltage of the pressure pump device, the specified upper voltage limit, and the safety margin.

[0038] When the target pressure increase is less than or equal to the maximum pressure increase margin, the target pressure increase is determined as the pressure increase value to be sent to the pressure pump device and the pressure pump device is controlled to perform pressure increase.

[0039] When the target pressure increase is greater than the maximum pressure increase margin, the maximum pressure increase margin is determined as the pressure increase value to be sent to the pressure pump device and the pressure pump device is controlled to perform pressure increase.

[0040] For example, voltage data of key nodes in the lower layer of the transformer substation is collected in real time. When the proportion of low-voltage over-limit nodes exceeds 50%, the substation is determined to be in an overall low-voltage over-limit state, triggering the global voltage boost regulation control process of the head-end pressure pump device. To avoid misjudgment caused by single-point abnormal data, the voltage boost target amplitude is not directly adopted using the maximum over-limit amount, but is calculated according to the following steps: Collect the current node voltage value and required compensation amount (i.e., the voltage increase required to restore to the acceptable lower limit) of all low-voltage over-limit nodes, and sort them from largest to smallest compensation amount; select the top 10% of nodes as key samples; calculate the weighted average compensation amount of these nodes as the initial expected voltage increase target of the system. The weight of each key node is determined by its current state: if the node is in normal state (i.e., its associated pump unit is operating normally and communication is online), it is assigned a basic weight. If a node is in a faulty state, then it is assigned an enhancement weight. (suggestion (Take a value of 2.0~3.0, which can be adjusted to highlight the higher sensitivity of the fault area to the global voltage.) The calculation method for the target boost amplitude is as follows: in, Indicates the target boost level. This represents the amount of compensation required for the i-th low-voltage over-limit node. , This represents the weight of the i-th low-voltage over-limit node. Indicates the basic weight. denoted by , where represents the enhancement coefficient of the i-th low-voltage over-limit node, and n represents the number of low-voltage over-limit nodes selected.

[0041] Before issuing the boost command, the current output voltage at the first terminal is read in real time, and combined with the upper limit of the first terminal voltage specified in the standard, the maximum available boost margin is calculated. in, Indicates the maximum boost margin. This indicates the specified upper limit of voltage. Indicates the current output voltage. This indicates a safety margin.

[0042] The expected voltage boost is compared with the initial safety margin. The actual voltage boost value is then issued. Take the smaller of the two values: when When this indicates sufficient headroom, pressure is increased according to end-user demand; when When the voltage is increased according to the expected demand, it will cause the high voltage at the beginning to exceed the limit. At this time, the pump at the beginning sacrifices part of the voltage recovery effect at the end and locks at the maximum safe output value.

[0043] When the head pump has output to the maximum limit However, if there are still large areas of low voltage nodes in the distribution area, it indicates that relying solely on the first-end voltage regulation is no longer sufficient to solve the current grid over-limit problem, and it is necessary to use mid-end and end-end pressure pump devices for coordinated management.

[0044] For large-scale high-voltage over-limit situations in the transformer area.

[0045] If all unidirectional over-limits in all branch nodes are high-voltage over-limits, and the proportion of high-voltage over-limits exceeds a first preset ratio, a global pressure reduction regulation process is triggered, controlling the operation of the head-end pressure pump device. The pressure reduction regulation process includes: The compensation amount is determined based on the current node voltage and corresponding rated value at the high voltage over-limit point.

[0046] The compensation amounts are sorted from largest to smallest, and the average value of the compensation amounts at the preset percentage before sorting is calculated to obtain the target voltage reduction range. The weight ratio of faulty nodes is greater than that of normal nodes.

[0047] The maximum voltage drop margin is obtained based on the current outlet voltage of the pressure pump device, the specified lower voltage limit, and the safety margin.

[0048] When the target pressure reduction is less than or equal to the maximum pressure reduction margin, the target pressure reduction is determined as the pressure reduction value to be sent to the pressure pump device and the pressure pump device is controlled to perform pressure reduction.

[0049] When the target pressure reduction is greater than the maximum pressure reduction margin, the maximum pressure reduction margin is determined as the pressure reduction value to be sent to the pressure pump device and the pressure pump device is controlled to perform pressure reduction.

[0050] For example, voltage data from key nodes such as the beginning, middle, and end of the transformer substation are collected in real time. When the proportion of high-voltage over-limit nodes exceeds 50%, the substation is determined to be in an overall high-voltage over-limit state, triggering the global voltage reduction regulation control process of the beginning-end pressure pump device. To prevent misjudgment due to single-point abnormal data, the weighted average of the required compensation amounts for the first 10% of high-voltage over-limit nodes can be taken. The weighting calculation method is the same as above, and this value serves as the initial expected voltage reduction target for the system. in, Indicates the target reduction range. This represents the compensation amount required for the j-th high-voltage over-limit node. , This represents the weight of the j-th high-voltage over-limit node. Indicates the basic weight. denoted by , where represents the enhancement coefficient of the j-th high-voltage over-limit node, and m represents the number of high-voltage over-limit nodes selected.

[0051] Before issuing the voltage reduction command, the current output voltage at the first terminal is read in real time, and the maximum available voltage reduction margin is calculated based on the lower limit of the first terminal voltage specified in the standard. in, Indicates the maximum voltage drop margin. Indicates the lower limit of the specified voltage. Indicates the current output voltage. This indicates a safety margin.

[0052] The target voltage reduction range is compared with the maximum voltage reduction margin. The actual voltage reduction value is then issued. Take the smaller of the two values: when When this indicates sufficient headroom, pressure should be reduced according to end-user demand; when When the voltage is reduced according to the expected demand, it will cause the low voltage at the first end to exceed the limit. At this time, the first end pump sacrifices part of the end voltage recovery effect and locks at the maximum safe output value.

[0053] When the head pump has output to the maximum limit However, if there are still large areas of high-voltage nodes in the distribution area, it indicates that relying solely on the first-end voltage regulation is no longer sufficient to solve the current grid over-limit problem, and it is necessary to use mid-end and end-end pressure pump devices for coordinated management.

[0054] S4: If there are bidirectional over-limits in all branch nodes, or the proportion of unidirectional over-limits is lower than the first preset ratio, or there are still areas with voltage over-limits after global adjustment, the multi-area collaborative adjustment process is triggered to control the operation of the mid-end pressure pump device in multiple areas.

[0055] Specifically, when a transformer substation experiences bidirectional over-limit issues with both high and low voltage, or when the over-limit area does not exceed 50%.

[0056] In each region: If the unidirectional over-limit incident at the inlet node in the region is only a low-voltage over-limit incident, and the proportion of low-voltage over-limit incidents exceeds a first preset ratio, the region's boost regulation process is triggered, controlling the operation of the intermediate-level pressure pump device. If the unidirectional over-limit incident at the inlet node in the region is only a low-voltage over-limit incident, and the proportion of high-voltage over-limit incidents exceeds a first preset ratio, the region's de-voltage regulation process is triggered, controlling the operation of the intermediate-level pressure pump device. If asymmetrical over-limit incidents occur among the three phases at the end of the region, and the proportion of over-limit nodes in each phase exceeds a second preset ratio, the three-phase independent treatment operation of the intermediate-level pressure pump device at the corresponding branch node in the region is controlled. If high-voltage and low-voltage nodes coexist in the same phase at the end of the region, or the proportion of over-limit nodes is lower than the second preset ratio, the end-point pressure pump device is controlled to operate.

[0057] For example, when a transformer substation simultaneously experiences extreme conditions of exceeding both high and low voltage limits, the global voltage shift of a single node is no longer sufficient to meet the mitigation requirements. In this case, the control strategy of the first-end pump unit will switch to a multi-regional collaborative mode.

[0058] For high-voltage over-limit areas, a mid-range pressure pump is used to manage the situation, collecting voltage data from multiple user nodes at the lower level. When the proportion of high-voltage over-limit nodes exceeds 50%, the system is determined to be in an overall high-voltage state, triggering the voltage reduction control process of the mid-range pressure pump device.

[0059] For areas experiencing low voltage exceedances, a mid-range pressure pump is used to manage the situation, collecting voltage data from multiple user nodes at the lower level. When the proportion of nodes experiencing low voltage exceedances exceeds 50%, the system is determined to be in an overall low voltage state, triggering the boost control process of the mid-range pressure pump.

[0060] In addition, if voltage exceedances still occur after the initial treatment is completed, the intermediate pressure pump device will participate in the treatment. The treatment process is similar to the multi-regional collaborative mode described above.

[0061] For low-voltage over-limit areas, voltage data of key nodes below the intermediate-level pressure pump is collected in real time. When the proportion of low-voltage nodes exceeds 50%, it is determined that the overall voltage is low, triggering the voltage boosting control process of the intermediate-level pressure pump unit. The voltage boosting process is similar to that of the pressure boosting process of the first-level pressure pump unit in the distribution area.

[0062] For high-voltage over-limit areas, voltage data of key nodes below the intermediate-level pressure pump is collected in real time. When the proportion of high-voltage nodes exceeds 50%, it is determined that the entire system is in a high-voltage over-limit state, triggering the voltage reduction control process of the intermediate-level pressure pump unit. The voltage reduction process is similar to that of the pressure reduction process of the first-level pressure pump unit in the distribution area.

[0063] However, when phase-to-phase asymmetry occurs at the terminal, if one phase exceeds 50%, low-voltage over-limit occurs at the node, while another phase or two phases exceeding 50% result in high-voltage over-limit. Since the intermediate-phase pressure pump device has a three-phase imbalance control function, that is, each phase is controlled independently, the voltage control can be completed by the intermediate-phase pressure pump device. The control process for each phase still follows the voltage boosting or voltage reducing process.

[0064] For situations where both high and low voltage exceedances occur simultaneously at the end of a circuit, or where no more than 50% of nodes experience exceedances, the initial or intermediate voltage pumps are completely ineffective when a single-phase line under the intermediate voltage pump device experiences both low and high voltage exceedances simultaneously. In such cases, the end-point voltage pump device needs to be activated for precise point-to-point remediation. When no more than 50% of nodes experience voltage exceedances, to ensure the overall pass rate of the distribution area, the intermediate voltage pump device will not activate, and the end-point voltage pump device will be controlled for point-to-point remediation.

[0065] S5: If the voltage exceeds the limit at the inlet node after adjustment by the first-end pump device and the middle-end pump device, then control the end pump device at the inlet node to work.

[0066] Specifically, such as Figure 3 As shown in the diagram, the cascaded voltage control system (first, middle, and last phases) has a dashed line representing the real-time voltage value from the first to the last phase before control. After the first and middle phases have performed complete local and regional level regulation, if residual voltage exceedances still exist at some remote nodes or heavily loaded / high photovoltaic penetration branches at the last phase, the system will officially activate the last-phase pressure pump device to implement point-to-point precise control, serving as the last line of defense to ensure the voltage compliance rate for all users in the entire distribution area. When high and low voltage exceedances coexist in the same phase, the last-phase pressure pump device also performs precise control. Figure 3 As shown, after three levels of treatment—the beginning, middle, and end—the voltage reaching the user side is around 220V, which meets the electricity needs of households.

[0067] In the three-tiered governance system of the transformer substation, when any equipment in any stage is out of service due to failure or maintenance, the system will automatically activate an emergency reconfiguration strategy. The remaining normal upstream and downstream levels will dynamically adjust compensation strategies through cross-level collaboration to make up for the missing regulation capacity and maximize the voltage qualification rate of the transformer substation.

[0068] If the first-end pump unit fails, the control bypass switch will be closed to disconnect the first-end pump unit from the low-voltage distribution network, and the global voltage regulation task will be transferred to the middle-end pump unit and the end-end pump unit in the voltage over-limit area.

[0069] Specifically, when the first-end voltage regulator fails, it immediately uses its bypass switch to quickly disconnect the power module from the system, simultaneously transferring the global voltage regulation task to the intermediate-end voltage regulator in the voltage over-limit region. The intermediate-end voltage regulator continues to operate according to its original over-limit handling procedure, but because the global reference regulation capability is lost after the first-end voltage regulator disconnects, the intermediate-end voltage regulator needs to undertake a greater compensation depth to compensate for the lack of global regulation. If voltage over-limit conditions still occur at the end after compensation by the intermediate-end voltage regulator, the end-end voltage regulator will perform precise point-to-point remediation, such as... Figure 4 As shown.

[0070] If the intermediate-level pressure pump unit malfunctions, a fault warning message is sent to the primary-level pressure pump unit. The primary-level pressure pump unit extracts voltage data from the intermediate-level faulty node and the voltage data from the same over-limit nodes in the branch nodes. If the number of intermediate-level faulty nodes does not exceed the third preset proportion of the total number of the same over-limit nodes in the branch nodes, the regional voltage regulation task is transferred to the terminal pressure pump unit in that region. If the number of intermediate-level faulty nodes exceeds the third preset proportion of the total number of the same over-limit nodes in the branch nodes, the weight of the intermediate-level faulty nodes is increased, the voltage boost target amplitude is recalculated to increase the output voltage of the primary-level pressure pump unit, and then the voltage regulation work of the terminal pressure pump unit at the inlet node where voltage over-limit still exists is controlled. Figure 5 As shown.

[0071] Specifically, when a fault occurs in the operating intermediate pump unit, the internal bypass switch of the unit quickly activates, safely disconnecting the faulty intermediate pump unit and ensuring that the power supply to the end load is absolutely uninterrupted. At the same time, the faulty intermediate pump unit immediately sends a fault warning message to the first pump unit in real time.

[0072] When the number of intermediate fault nodes does not exceed 50% of the total number of intermediate over-limit nodes, the system determines it as a localized minor fault. At this time, to avoid excessive intervention in the overall power grid, the remediation task is directly delegated to the end-point pumping units under the faulty intermediate pumping unit. The end-point pumping units initiate precise point-to-point remediation to independently restore voltage in the affected area.

[0073] When the number of faulty nodes in the middle reaches accounts for 50% or more of the total number of nodes exceeding the limit in the middle reaches, the system determines that there is a significant gap in the middle reaches regulation capacity. The first-end pressure pump device extracts data including the faulty nodes in the middle reaches and all key nodes in the same exceeding-limit state as the faulty nodes, recalculates the weighted average compensation amount, increases the weight factor of the faulty nodes in the middle reaches, and the first-end pressure pump correspondingly increases its output amplitude to maximize the filling of the governance gap caused by the faulty nodes in the middle reaches. After the first-end pressure pump device completes the main regulation compensation, if voltage exceeding limits still exist in the lower-level branch lines, the last-end pressure pump device implements local point-to-point precise reinforcement as the last line of defense to ensure the voltage qualification rate. In this state, other healthy middle reaches in different exceeding-limit states than the faulty nodes in the middle reaches independently perform routine governance.

[0074] If the terminal pump unit fails, a fault warning message is sent to the intermediate pump unit. The intermediate pump unit extracts the voltage data at the terminal fault node and the voltage data at the same over-limit node in the same area, increases the weight of the terminal fault node, and recalculates the voltage boost target amplitude to increase the output voltage of the intermediate pump unit.

[0075] For example, when a fault occurs in the operating end-point pump unit, the internal bypass switch of the end-point pump unit will quickly activate, safely disconnecting the faulty end-point pump unit immediately to ensure that the user's normal power supply is completely uninterrupted. At the same time, the faulty end-point pump unit will immediately send a fault warning message to the upstream intermediate-point pump unit in real time.

[0076] The mid-range pressure pump unit extracts data from the terminal fault node and other key nodes in the same out-of-limit state as the terminal fault node. It then recalculates the weighted average compensation amount, increases the weight factor of the fault node, and accordingly enhances the output amplitude of the mid-range pressure pump unit to maximize the filling of the governance gap caused by the terminal fault. For non-faulty nodes in a different out-of-limit state from the terminal fault node, their respective normally operating terminal pressure pump units perform point-to-point precise governance.

[0077] In addition, to ensure that the intermediate-end pump unit has sufficient voltage regulation margin to handle terminal faults, the weight of the intermediate-end pump node can be increased accordingly by first adjusting the first-end pump unit, actively increasing the output amplitude of the first-end pump unit, and then controlling the intermediate-end pump unit to perform the above adjustments. Figure 6 As shown, this ultimately forms a governance link with expanded adjustment space at the beginning and full output in the middle, striving to ensure the voltage quality of users at the fault end.

[0078] Specifically, if the terminal pump device fails, a fault warning message is sent to the intermediate pump device and simultaneously to the head pump device. First, the weight of the intermediate pump device in the area where the terminal pump device is located is increased, and the voltage rise target amplitude in the regulation process corresponding to the head pump device is recalculated to increase the output voltage of the head pump device. Then, the weight of the terminal fault node is increased, and the voltage rise target amplitude in the regulation process corresponding to the intermediate pump device is recalculated to increase the output voltage of the intermediate pump device.

[0079] Because the pumping units at each node in a low-voltage distribution network need to have bidirectional high and low voltage control capabilities, the internal circuitry of the pumping units must be designed accordingly. Figure 7 As shown, the circuit within the pump device is a single-stage AC / AC converter circuit, which includes: Input-side inductor, output-side inductor, energy storage capacitor, first bridge arm, and second bridge arm.

[0080] The first bridge arm includes a first upper bridge arm and a first lower bridge arm, which are electrically connected; the second bridge arm includes a second upper bridge arm and a second lower bridge arm, which are electrically connected.

[0081] The two ends of the first bridge arm are connected to the two ends of the second bridge arm, and also to the two ends of the energy storage capacitor; one end of the input-side inductor is connected to the connection between the first upper bridge arm and the first lower bridge arm, and the other end of the input-side inductor is connected to one end of the input side, and the other end of the input side is connected to one end of the energy storage capacitor; one end of the output-side inductor is connected to the connection between the second upper bridge arm and the second lower bridge arm, and the other end of the output-side inductor is connected to one end of the output side, and the other end of the output side is connected to one end of the energy storage capacitor.

[0082] For example, such as Figure 7As shown, in the first-end pump device, the input side of the circuit is connected to the output side of the transformer in the distribution area, and the output side is connected to the main line of the low-voltage power grid; in the middle-end pump device, the input side of the circuit is connected to the main line of the low-voltage power grid, and the output side is connected to the branch line; in the last-end pump device, the input side of the circuit is connected to the line of the corresponding phase, and the output side is connected to the actual load. The first upper bridge arm is composed of switch unit T1 and switch unit T2 connected together, and the first lower bridge arm is composed of switch unit T3 and switch unit T4 connected together. The first upper bridge arm is connected to the first lower bridge arm, that is, the end of switch unit T2 in the first upper bridge arm that is away from switch unit T1 is connected to the end of switch unit T3 in the first lower bridge arm that is away from switch unit T4. The second upper bridge arm is composed of switch unit T5 and switch unit T6 connected together, and the second lower bridge arm is composed of switch unit T7 and switch unit T8 connected together. The second upper bridge arm is connected to the second lower bridge arm, that is, the end of switch unit T6 in the second upper bridge arm that is away from switch unit T5 is connected to the end of switch unit T7 in the second lower bridge arm that is away from switch unit T8. The two ends of the energy storage capacitor C0 are connected to the two ends of the first bridge arm and the second bridge arm, respectively. Specifically, one end of the energy storage capacitor C0 is connected to the end of the first upper bridge arm where the switch unit T1 is furthest from switch unit T2, and the end of the second upper bridge arm where the switch unit T5 is furthest from switch unit T6. The other end of the energy storage capacitor C0 is connected to the end of the first lower bridge arm where the switch unit T4 is furthest from switch unit T3, and the end of the second lower bridge arm where the switch unit T8 is furthest from switch unit T7. One end of the input-side inductor L1 is connected at the junction of the first upper bridge arm and the first lower bridge arm, i.e., at the junction of switch unit T2 and switch unit T3; the other end of the input-side inductor L1 is connected to one end of the input side, and the other end of the input side is connected to one end of the energy storage capacitor C0. One end of the output-side inductor L2 is connected to the junction of the second upper bridge arm and the second lower bridge arm, i.e., the junction of the switching unit T6 and the switching unit T7; the other end of the output-side inductor L2 is connected to one end of the output side, and the other end of the output side is connected to one end of the energy storage capacitor C0. Therefore, the other end of the input side is connected to the other end of the output side.

[0083] When the input voltage is lower than the preset voltage, the second upper bridge arm is kept on, and the first upper bridge arm and the first lower bridge arm are alternately and complementaryly turned on. By increasing the duty cycle of the first lower bridge arm, low voltage boost compensation is achieved. When the input voltage is higher than the preset voltage, the first upper bridge arm is kept on, and the second upper bridge arm and the second lower bridge arm are alternately and complementaryly turned on. By decreasing the duty cycle of the second upper bridge arm, high voltage step-down management is achieved.

[0084] The existing solution involves rectifying AC to DC and then inverting it back to AC, which results in efficiency losses due to the two-stage energy conversion and requires a large-capacity DC bus capacitor, leading to bulky equipment and limited lifespan.

[0085] The topology of this embodiment, through the ingenious configuration of the input-side inductor, output-side inductor, energy storage capacitor, and the first and second bridge arms, achieves direct AC-AC voltage conversion without the need for an intermediate DC link. The coordinated operation of the first and second bridge arms, along with the rational configuration of the input-side inductor, output-side inductor, and energy storage capacitor, optimizes the energy transmission path, fundamentally avoiding energy conversion losses in the intermediate DC link, effectively reducing energy loss, and improving the overall system operating efficiency. Simultaneously, by eliminating the traditional DC bus capacitor, the topology of this embodiment does not require a large-capacity DC bus capacitor to stabilize the DC voltage, significantly reducing the capacity requirement of the energy storage capacitor. This not only allows for a significant reduction in device size, facilitating deployment in space-constrained environments, but also extends the lifespan of the capacitor components and reduces system maintenance costs. The technical solution of this embodiment effectively solves the technical problems of low efficiency, large size, and short lifespan in existing technologies while achieving high and low voltage management.

[0086] like Figure 7 As shown, the first upper bridge arm, the first lower bridge arm, the second upper bridge arm, and the second lower bridge arm each include two switching units. These switching units are controlled to open and close, enabling bidirectional conduction of the first upper bridge arm, the first lower bridge arm, the second upper bridge arm, and the second lower bridge arm. Each switching unit includes a switching transistor and a diode. The current input terminal of the switching transistor is connected to the negative terminal of the diode, and the current output terminal of the switching transistor is connected to the positive terminal of the diode. Two switching units in the same bridge arm are connected top-to-bottom.

[0087] Specifically, the switching transistor can be an insulated gate bipolar transistor (IGBT) or a metal-oxide-semiconductor field-effect transistor (MOSFET), and the diode can be a fast recovery diode or a Schottky diode; alternatively, the switching transistor can also be a wide bandgap semiconductor device such as silicon carbide (SiC) or gallium nitride (GaN) to achieve higher switching frequencies and lower losses, and the diode can be a matching SiC Schottky diode.

[0088] The first bridge arm consists of switch units T1, T2, T3, and T4. Switch units T1 and T2 form a top-to-bottom switch for the first upper bridge arm, and switch units T3 and T4 form a top-to-bottom switch for the first lower bridge arm. The second bridge arm consists of switch units T5, T6, T7, and T8. Switch units T5 and T6 form a top-to-bottom switch for the second upper bridge arm, and switch units T7 and T8 form a top-to-bottom switch for the second lower bridge arm.

[0089] During the positive and negative half-cycles of the AC voltage, the on / off state of each pair of top-side switching units in the control bridge arm forms a controllable conduction path. For example, taking the first upper bridge arm as an example, during the positive half-cycle of the AC voltage, the switching transistor in switching unit T1 can be controlled to conduct, and the current passes through the diode in switching unit T2 and the switching transistor in switching unit T1 to form a path, thus making the first bridge arm conduct as a whole. During the negative half-cycle of the AC voltage, the switching transistor in switching unit T2 can be controlled to conduct, and the current passes through the switching transistor in switching unit T2 and the diode in switching unit T1 to form a path, thus making the first bridge arm conduct as a whole. This ensures that the first bridge arm can maintain conduction in both the positive and negative half-cycles of the AC voltage, achieving bidirectional conduction of the first bridge arm and avoiding current interruption caused by unidirectional switches or unidirectional switching units when the AC voltage is reversed.

[0090] External control signals control the on / off states of the first upper bridge arm, the first lower bridge arm, the second upper bridge arm, and the second lower bridge arm, actively turning on or off the switching transistors that make up these bridge arms. This control can be achieved in various ways. For example, a microcontroller or digital signal processor (DSP) can generate pulse width modulation (PWM) signals to drive the switching devices according to a preset control algorithm, or the switching state can be adjusted in real time by detecting the input voltage and output current. By precisely controlling the on / off states of each bridge arm, a controllable conduction path can be formed during the positive and negative half-cycles of the AC voltage.

[0091] This circuit has four operating modes. Since it is a bidirectional AC / AC topology, only the positive half-cycle of AC will be discussed below (e.g., ...). Figure 7 As shown, the current flows out from the upper end of the input side), and the specific states of the four operating modes are as follows.

[0092] Operating Mode 1: Controlling the first and second upper bridge arms to conduct; at this time, the current flows through the input side, the input side inductor L1, and the first upper bridge arm, then splits into two branches. One branch flows through the energy storage capacitor C0 to the input side, and the other branch flows through the second upper bridge arm, the output side inductor L2, and the output side to the input side. For example... Figure 7 As shown, the switching transistors in switching unit T1 and switching unit T6 are turned on, while the other switching transistors are turned off. The current flow path is: input side → L1 → T2 → T1 → C0 → input side, input side → L1 → T2 → T1 → T5 → T6 → L2 → output side → input side. At this time, the input side charges and stores energy for the input side inductor L1, the output side inductor L2, and the energy storage capacitor C0, and simultaneously supplies power to the output side. Similarly, to keep the first and second upper bridge arms on, during the negative half-cycle of AC (e.g., ... Figure 7 As shown, the current flows out from the lower end of the input side. This can be changed to control the switching transistors in the switching unit T2 and the switching transistors in the switching unit T5 to be turned on, while the other switching transistors are turned off, which can achieve the same effect as the above circuit flow path.

[0093] Operating Mode 2: Controlling the first upper bridge arm and the second lower bridge arm to conduct; at this time, the current flows through the input side, input side inductor L1, the first upper bridge arm, and energy storage capacitor C0 back to the input side; in addition, the energy stored in the output side inductor L2 is released to form current, which flows through the output side and the second lower bridge arm back to the output side inductor L2. For example... Figure 7 As shown, the switching transistors in switching unit T1 and T7 are turned on, while the other switching transistors are turned off. The current flow path is input side → L1 → T2 → T1 → C0 → input side. The output-side inductor L2 forms a freewheeling path through switching units T7 and T8 to supply power to the output side, while the input side charges the energy storage capacitor C0. Similarly, to keep the first upper bridge arm and the second lower bridge arm on, during the negative half-cycle of AC, the switching transistors in switching unit T2 and T8 can be turned on while the other switching transistors are turned off, achieving the same effect as the above-mentioned circuit flow path.

[0094] Operating Mode 3: Controlling the first and second lower bridge arms to conduct; at this time, the current flows through the input side, input-side inductor L1, and the first lower bridge arm back to the input side; additionally, the energy stored in the output-side inductor L2 is released, and the current flows through the output side and the second lower bridge arm back to the output-side inductor L2. For example... Figure 7 As shown, the switching transistors in switching unit T4 and T7 are turned on, while the other switching transistors are turned off. The current flow path is: input side → L1 → T3 → T4 → input side, output side → L2 → T7 → T8 → output side. At this time, the output-side inductor L2 releases energy to supply power to the output side, and the input side charges the input-side inductor L1. Similarly, to keep the first and second lower bridge arms on, during the negative half-cycle of AC, the switching transistors in switching unit T3 and T8 can be turned on, while the other switching transistors are turned off, achieving the same effect as the above circuit flow path.

[0095] Operating Mode 4: Controls the first lower bridge arm and the second upper bridge arm to conduct; at this time, the current flows through the input side, the input side inductor L1, and the first lower bridge arm back to the input side; in addition, the energy stored in the energy storage capacitor C0 is released, and the current flows through the second upper bridge arm, the output side inductor L2, and the output side back to the energy storage capacitor C0. For example... Figure 7As shown, the switching transistors in switching unit T4 and T5 are turned on, while the other switching transistors are turned off. The current flow path is: input side → L1 → T3 → T4 → input side, C0 → T5 → T6 → L2 → output side → C0. At this time, the output-side inductor L2 and the energy storage capacitor C0 release energy to supply power to the output side, while the input side charges the input-side inductor L1. Similarly, to keep the first lower bridge arm and the second upper bridge arm on, during the negative half-cycle of AC, the switching transistors in switching unit T3 and T6 can be turned on, while the other switching transistors are turned off, achieving the same effect as the above circuit flow path.

[0096] The output voltage V0 is calculated as follows: Output voltage V0 = D2 * Vin / (1 - D1), where D1 is the duty cycle of the first lower bridge arm, 1 - D1 is the duty cycle of the first upper bridge arm, D2 is the duty cycle of the second upper bridge arm, 1 - D2 is the duty cycle of the second lower bridge arm, and Vin is the input voltage. Before control, based on the above mathematical formula, and knowing the input voltage and output voltage, the duty cycle D2 of the second upper bridge arm or the duty cycle D1 of the first lower bridge arm can be calculated. Since the input voltage may fluctuate due to the power supply capacity of the input side, a control strategy needs to be selected based on the comparison between the input voltage and the preset voltage.

[0097] When the input voltage is lower than the preset voltage, the second upper bridge arm is kept on (i.e., D2 equals 1), and the first upper and lower bridge arms are alternately and complementaryly turned on according to the calculated duty cycle D1 of the first lower bridge arm. Furthermore, as the AC current alternates regularly between the positive and negative half-cycles, for example, if the first lower bridge arm needs to be turned on, the switch in switching unit T4 is turned on during the positive half-cycle, and the switch in switching unit T3 is turned on during the negative half-cycle. The conduction control of the remaining bridge arms is similar. By keeping the first upper bridge arm on and controlling the second upper and lower bridge arms to alternately and complementaryly turn on, the circuit switches between operating mode 1 and operating mode 4. By increasing the duty cycle of the first lower bridge arm, low-voltage boost compensation is achieved. In this process, the energy storage capacitor C0 and the output-side inductor L2 form an output-side LC filter network. The energy storage capacitor C0 is used to buffer the pulsating energy generated during the switching process and suppress the voltage ripple of the intermediate node. The output-side inductor L2 is used to suppress the high-frequency current ripple of the output, thereby keeping the output voltage and output current smooth.

[0098] When the input voltage is higher than the preset voltage, the first upper bridge arm is kept on (i.e., D1 equals 0), and the second upper bridge arm and the second lower bridge arm are alternately and complementaryly turned on according to the calculated duty cycle D2 of the second upper bridge arm. Furthermore, as the AC current alternates regularly between positive and negative half-cycles, for example, if the second upper bridge arm needs to be turned on, the switch in switching unit T6 is turned on during the positive half-cycle, and the switch in switching unit T5 is turned on during the negative half-cycle. The conduction control of the remaining bridge arms is similar. By keeping the first upper bridge arm on and controlling the second upper bridge arm and the second lower bridge arm to alternately and complementaryly turn on, the power grid switches between operating mode 1 and operating mode 2. By reducing the duty cycle of the second upper bridge arm, the output voltage is reduced, achieving high-voltage step-down management. In this process, the input-side inductor L1 and the energy storage capacitor C0 form an input-side LC filter network to suppress high-frequency current ripple and intermediate node voltage ripple generated by switching action, and reduce the propagation of high-frequency harmonics to the input side; the output-side inductor L2 maintains the continuity of the output-side current through energy storage and freewheeling, further improving the output waveform.

[0099] When the input voltage equals the preset voltage, the first upper bridge arm is kept on (i.e., D1 equals 0) and the second upper bridge arm is kept on (i.e., D2 equals 1), so that the input voltage is directly supplied to the output side through the external circuit without the need for step-up / step-down voltage management.

[0100] In summary, based on the deviation between the input voltage and the preset voltage, the duty cycle D1 of the first lower bridge arm (which can be regarded as the boost duty cycle) or the duty cycle D2 of the second upper bridge arm (which can be regarded as the buck duty cycle) is adjusted respectively, so that the circuit switches between low voltage boost compensation and high voltage buck management. By utilizing the energy storage and filtering effects of the input-side inductor L1, the output-side inductor L2, and the energy storage capacitor C0, the continuous, smooth, and stable adjustment of the output voltage is achieved.

[0101] This circuit can also be applied to three-phase systems. By adding this circuit between the input and output sides of each phase, the input ports in the circuit are replaced with the input ports of the corresponding phase, and the output ports are replaced with the output ports of the corresponding phase. By setting this circuit in each phase, the voltage of each phase can be individually boosted or bucked, further ensuring the balance and stability of the three-phase voltage.

[0102] The following examples illustrate this point.

[0103] Example 1, such as Figure 8 As shown, if there are only three branch nodes under this area, when a high voltage exceeds the limit at one branch node, the head pump device will not operate, and the middle pump device in this area will take over the treatment task.

[0104] If the intermediate pump device fails at this time, it sends a fault message to the first pump device. The first pump device takes on the task of remediation, calculates the minimum compensation amount to restore the qualified voltage of the node, takes the minimum value between this compensation amount and the maximum compensation margin of the transformer area, and uses the minimum value as the final compensation margin of the first pump device for voltage remediation. If the problem of exceeding the limit still occurs at the end after the first remediation is completed, the end pump will accurately remediate it.

[0105] Example 2, such as Figure 9 As shown, if there are only three branch nodes under this substation, when two branch nodes experience voltage over-limits and both high and low voltage over-limits occur simultaneously, the first-end pump device will not operate. The middle-end pump device in the low-voltage over-limit area will take on the task of boosting the voltage, and the middle-end pump device in the high-voltage over-limit area will take on the task of reducing the voltage.

[0106] If the intermediate pump unit in the low-voltage over-limit area malfunctions, it sends a fault message to the first-end pump unit. The first-end pump unit then takes over the rectification task, calculates the minimum compensation amount to restore the voltage to the correct level, and uses the minimum value between this compensation amount and the maximum compensation margin of the distribution area. This minimum value is used as the final compensation margin for the first-end pump unit to rectify the voltage. The intermediate pump unit in the high-voltage over-limit area independently performs the voltage over-limit rectification work in its area. If voltage over-limit still exists at the end, the end pump unit will handle the rectification.

[0107] Example 3, such as Figure 10 As shown, when a common high-voltage or low-voltage over-limit problem occurs in the same phase at the end, the intermediate pressure pump device can undertake the treatment task and only treat this phase because it adopts three-phase decoupling control.

[0108] Example 4, such as Figure 11 As shown, when one phase has a high voltage limit exceeding the limit and another phase has a low voltage limit exceeding the limit, the intermediate pressure pump device can undertake the treatment task because it adopts three-phase decoupling control. It uses voltage reduction to treat the phase with high voltage limit exceeding the limit and voltage increase to treat the phase with low voltage limit exceeding the limit.

[0109] Example 5, such as Figure 12 As shown, when both low-voltage and high-voltage limits coexist in a certain phase, the intermediate pump device will not work; only the terminal pump device will provide precise point-to-point treatment.

[0110] If the end pump fails at the high-voltage over-limit node, the end pump device sends a fault message to the intermediate pump device. The intermediate pump device calculates the minimum compensation amount to restore the qualified voltage of the node, takes the minimum value between this compensation amount and the maximum compensation margin of the intermediate pump device, and uses the minimum value as the final compensation margin of the intermediate pump device for voltage management. The end pump devices of the low-voltage over-limit node and the end pump devices of the normal node independently perform the voltage management work of their respective nodes.

[0111] This application provides a low-voltage distribution network full-chain cascaded management system based on a pressure pump device. Pressure pump devices are installed at the beginning, middle, and end of the low-voltage distribution network. The beginning pressure pump device is connected to the low-voltage side of the transformer substation to regulate the overall voltage. The middle pressure pump device is connected in series to the branch lines of the low-voltage distribution network to regulate the regional voltage of the corresponding area. The end pressure pump device is connected in series to the incoming line side of a single-phase user to regulate the incoming voltage. The pressure pump devices are used to manage voltage boosting or bucking.

[0112] like Figure 13 As shown, the system includes: The data acquisition module 10 is used to collect voltage data at various nodes of the low-voltage distribution network in real time. The nodes include transformer substation nodes, branch nodes, and household access nodes.

[0113] The node analysis module 20 is used to compare the voltage at each node with the corresponding rated value to determine the status of each node, including low voltage over-limit, normal and high voltage over-limit.

[0114] The first-end controller 30 is used to trigger a global adjustment process and control the first-end pressure pump device to work if there is only one-way over-limit among all branch nodes and the proportion of one-way over-limit exceeds the first preset ratio.

[0115] The intermediate controller 40 is used to trigger a multi-region collaborative adjustment process and control the operation of the intermediate pressure pump device in multiple regions if there are bidirectional over-limits in all branch nodes, or the proportion of unidirectional over-limits is lower than the first preset ratio, or there are still areas with voltage over-limits after global adjustment.

[0116] The terminal controller 50 is used to control the terminal pump device at the household entrance node to operate if the voltage exceeds the limit after adjustment by the first-end pump device and the middle-end pump device.

[0117] In this optional embodiment, by deploying the first-end pressure pump device, the middle-end pressure pump device, and the last-end pressure pump device in a fully cascaded manner, and introducing a hierarchical cascaded control strategy based on voltage over-limit status, the most suitable adjustment level can be dynamically selected according to the global or regional characteristics of the grid voltage problem. When only unidirectional over-limit exists among all branch nodes and its proportion exceeds a first preset ratio, a global adjustment process is triggered, and the first-end pressure pump device performs unified adjustment, avoiding global problems caused by local adjustment; when there are bidirectional over-limits or a low proportion of unidirectional over-limits, a multi-regional collaborative adjustment process is triggered, and the middle-end pressure pump device performs precise treatment for specific regions, preventing circulating currents or resonances that may be caused by single-link adjustment; for voltage over-limits at the inlet node that still exist after the first two levels of adjustment, the last-end pressure pump device performs final compensation to ensure that the voltage at the user end is qualified. Through the above technical solution, this application effectively solves the problem that the existing mechanical voltage regulation in the distribution area cannot achieve continuous and smooth voltage regulation and is prone to under-regulation or over-regulation. At the same time, it overcomes the defects of single-link governance measures lacking pertinence and poor effect, realizes refined dynamic tracking of low-voltage distribution network voltage and full-chain collaborative governance, and significantly improves power supply quality and system stability.

[0118] In summary, compared with existing technologies, it has the following beneficial effects: 1. It breaks through the limitations of traditional single-point compensation equipment. For extreme operating conditions caused by high photovoltaic penetration or heavy load, where high and low voltage exceedances occur simultaneously in the same distribution area or even the same branch line, the system can solve the problem by adopting a strategy of non-action at the first and middle ends and precise point-to-point treatment at the end.

[0119] 2. A three-dimensional defense system for joint management of the first, middle and last sections of low-voltage distribution substations has been formed, filling the technical challenge of lacking effective management methods for the middle sections of low-voltage distribution network branches.

[0120] 3. Seamless fault reconfiguration and cross-level support. When any level device fails and exits, the weight of the faulty node is dynamically increased, enabling healthy levels to increase their output amplitude and ensuring local voltage quality.

[0121] 4. Seamless switching between dual modes: When communication is normal, the system achieves optimal global coordination; when communication is interrupted in harsh environments, each MCU can seamlessly switch to an independent working mode, relying on local high-precision sampling to independently maintain the rated voltage, providing a solid safety net.

[0122] 5. Hardware advantages of single-stage topology: It adopts a single-stage AC / A conversion circuit, eliminating the need for large-capacity DC energy storage capacitors in traditional AC-DC-AC conversion, which significantly improves the power density, dynamic response speed and operational reliability throughout the entire life cycle of the hardware.

[0123] It should be noted that, in this document, relational terms such as "first" and "second" are used only to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitations, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes said element.

[0124] The above embodiments are only used to illustrate the technical solutions of this application, and are not intended to limit them. Although this application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of this application.

Claims

1. A method for cascaded management of the entire low-voltage distribution network based on a pressure pump device, characterized in that, A voltage booster is installed at the beginning, middle, and end of the low-voltage distribution network. The voltage booster at the beginning is connected to the low-voltage side of the transformer in the distribution area to regulate the overall voltage. The voltage booster at the middle is connected in series to the branch lines of the low-voltage distribution network to regulate the area voltage of the corresponding area. The voltage booster at the end is connected in series to the incoming line side of a single-phase user to regulate the incoming voltage. The voltage booster is used to control voltage rise or fall. The method includes: Real-time collection of voltage data at various nodes in the low-voltage distribution network, including transformer substation nodes, branch nodes, and household access nodes; Compare the voltage at each node with the corresponding rated value to determine the status of each node, which includes low voltage over-limit, normal, and high voltage over-limit. If only one-way limit exceedance exists among all branch nodes, and the proportion of one-way limit exceedance exceeds the first preset ratio, the global adjustment process is triggered to control the operation of the head pump device. If there are bidirectional over-limits in all branch nodes, or the proportion of unidirectional over-limits is lower than the first preset ratio, or there are still areas with voltage over-limits after global adjustment, the multi-area collaborative adjustment process is triggered to control the operation of the mid-end pressure pump device in multiple areas. If, after adjustment by the first-end pump and the middle-end pump, the voltage at the inlet node still exceeds the limit, then the end pump at that inlet node will be controlled to operate.

2. The low-voltage distribution network full-chain cascade management method based on a pressure pump device as described in claim 1, characterized in that, If only one-way limit violations exist among all branch nodes, and the proportion of one-way limit violations exceeds a first preset ratio, the global adjustment process is triggered to control the operation of the head-end pressure pump device, including: If the only one-way over-limit in all branch nodes is the low-pressure over-limit, and the proportion of low-pressure over-limit exceeds the first preset ratio, the global pressure boosting regulation process is triggered, and the head pump device is controlled to work. If the only one-way over-limit in all branch nodes is the high-voltage over-limit, and the proportion of high-voltage over-limit exceeds the first preset ratio, the global pressure reduction regulation process is triggered, and the head pump device is controlled to work.

3. The low-voltage distribution network full-chain cascaded management method based on a pressure pump device as described in claim 1, characterized in that, The process of triggering multi-region coordinated adjustment and controlling the operation of the mid-range pressure pump device in multiple regions includes: In each region: If the one-way over-limit of the inlet node in the area is only low-voltage over-limit, and the proportion of low-voltage over-limit exceeds the first preset ratio, the area's pressure boosting adjustment process is triggered, and the intermediate pressure pump device is controlled to work. If the one-way over-limit of the inlet node in the area is only low-voltage over-limit, and the proportion of high-voltage over-limit exceeds the first preset ratio, the area's pressure reduction adjustment process is triggered, and the intermediate pressure pump device is controlled to work. If an asymmetrical limit is exceeded among the three phases at the end of the region, and the proportion of limit-exceeding nodes for each phase exceeds the second preset ratio, then the three-phase independent treatment of the intermediate pressure pump device at the corresponding branch node of the control region will be carried out. If high-voltage and low-voltage nodes coexist in the terminal phase of the region, or if the proportion of nodes exceeding the limit is lower than the second preset ratio, then the terminal pressure pump device will be controlled to operate.

4. The low-voltage distribution network full-chain cascade management method based on a pump device as described in claim 2 or 3, characterized in that, The boost regulation process includes: The compensation amount is determined based on the current node voltage and corresponding rated value at the low-voltage over-limit point; The compensation amounts are sorted from largest to smallest, and the average of the compensation amounts at the preset percentage before sorting is calculated to obtain the target boost amplitude. Among them, the weight ratio of faulty nodes is greater than that of normal nodes. The maximum pressure margin is obtained based on the current outlet voltage of the pressure pump device, the specified upper voltage limit, and the safety margin. When the target pressure increase is less than or equal to the maximum pressure increase margin, the target pressure increase is determined as the pressure increase value to be sent to the pressure pump device and the pressure pump device is controlled to perform pressure increase. When the target pressure increase is greater than the maximum pressure increase margin, the maximum pressure increase margin is determined as the pressure increase value to be sent to the pressure pump device and the pressure pump device is controlled to perform pressure increase.

5. The low-voltage distribution network full-chain cascaded management method based on a pump device as described in claim 2 or 3, characterized in that, The voltage reduction regulation process includes: The compensation amount is determined based on the current node voltage and corresponding rated value at the high voltage over-limit point; The compensation amounts are sorted from largest to smallest, and the average of the compensation amounts at the preset percentage before sorting is calculated to obtain the target voltage reduction range. Among them, the weight ratio of faulty nodes is greater than that of normal nodes. The maximum voltage drop margin is obtained based on the current outlet voltage of the pressure pump device, the specified lower voltage limit, and the safety margin. When the target pressure reduction is less than or equal to the maximum pressure reduction margin, the target pressure reduction is determined as the pressure reduction value to be sent to the pressure pump device and the pressure pump device is controlled to perform pressure reduction. When the target pressure reduction is greater than the maximum pressure reduction margin, the maximum pressure reduction margin is determined as the pressure reduction value to be sent to the pressure pump device and the pressure pump device is controlled to perform pressure reduction.

6. The low-voltage distribution network full-chain cascaded management method based on a pressure pump device as described in claim 1, characterized in that, Also includes: If the first-end pump device fails, the control bypass switch is closed to disconnect the first-end pump device from the low-voltage distribution network and transfer the global voltage regulation task to the middle-end pump device and the end-end pump device in the voltage over-limit area. If the intermediate pump unit fails, a fault warning message is sent to the primary pump unit. The primary pump unit extracts the voltage data at the intermediate fault node and the voltage data at the same over-limit nodes in the branch nodes. If the number of intermediate fault nodes does not exceed the third preset proportion of the total number of the same over-limit nodes in the branch nodes, the regional voltage regulation task is transferred to the terminal pump unit in that region. If the number of intermediate fault nodes exceeds the third preset proportion of the total number of the same over-limit nodes in the branch nodes, the weight of the intermediate fault nodes is increased, the voltage rise target amplitude is recalculated to increase the output voltage of the primary pump unit, and then the terminal pump unit at the inlet node where there is still a voltage over-limit is controlled to perform voltage regulation. If the terminal pump unit fails, a fault warning message is sent to the intermediate pump unit. The intermediate pump unit extracts the voltage data at the terminal fault node and the voltage data at the same over-limit node in the same area, increases the weight of the terminal fault node, and recalculates the voltage boost target amplitude to increase the output voltage of the intermediate pump unit.

7. The low-voltage distribution network full-chain cascade management method based on a pressure pump device as described in claim 6, characterized in that, Also includes: If the terminal pump unit fails, a fault warning message is sent to the intermediate pump unit and simultaneously to the head pump unit. First, the weight of the intermediate pump unit in the area where the terminal pump unit is located is increased, and the voltage rise target amplitude in the regulation process corresponding to the head pump unit is recalculated to increase the output voltage of the head pump unit. Then, the weight of the terminal fault node is increased, and the voltage rise target amplitude in the regulation process corresponding to the intermediate pump unit is recalculated to increase the output voltage of the intermediate pump unit.

8. The low-voltage distribution network full-chain cascaded management method based on a pressure pump device as described in claim 1, characterized in that, The circuit within the pump device is a single-stage AC / AC converter circuit, which includes: Input-side inductor, output-side inductor, energy storage capacitor, first bridge arm, and second bridge arm; The first bridge arm includes a first upper bridge arm and a first lower bridge arm, which are electrically connected; the second bridge arm includes a second upper bridge arm and a second lower bridge arm, which are electrically connected. The two ends of the first bridge arm are connected to the two ends of the second bridge arm, and also to the two ends of the energy storage capacitor; one end of the input-side inductor is connected to the connection between the first upper bridge arm and the first lower bridge arm, and the other end of the input-side inductor is connected to one end of the input side, and the other end of the input side is connected to one end of the energy storage capacitor; one end of the output-side inductor is connected to the connection between the second upper bridge arm and the second lower bridge arm, and the other end of the output-side inductor is connected to one end of the output side, and the other end of the output side is connected to one end of the energy storage capacitor.

9. The low-voltage distribution network full-chain cascade management method based on a pressure pump device as described in claim 8, characterized in that, The first upper bridge arm, the first lower bridge arm, the second upper bridge arm, and the second lower bridge arm each include two switching units to control the switching units to achieve bidirectional conduction of the first upper bridge arm, the first lower bridge arm, the second upper bridge arm, and the second lower bridge arm. Each switching unit includes a switching transistor and a diode. The current input terminal of the switching transistor is connected to the negative terminal of the diode, and the current output terminal of the switching transistor is connected to the positive terminal of the diode. Two switching units in the same bridge arm are connected top to top.

10. A low-voltage power distribution network full-chain cascaded management system based on a pressure pump device, characterized in that, A voltage booster is installed at the beginning, middle, and end of the low-voltage distribution network. The voltage booster at the beginning is connected to the low-voltage side of the transformer in the distribution area to regulate the overall voltage. The voltage booster at the middle is connected in series to the branch lines of the low-voltage distribution network to regulate the area voltage of the corresponding area. The voltage booster at the end is connected in series to the incoming line side of a single-phase user to regulate the incoming voltage. The voltage booster is used to control voltage rise or fall. The system includes: The data acquisition module is used to collect voltage data at various nodes of the low-voltage distribution network in real time. These nodes include transformer substation nodes, branch nodes, and service access nodes. The node analysis module is used to compare the voltage at each node with the corresponding rated value to determine the status of each node, including low voltage over-limit, normal and high voltage over-limit. The head-end controller is used to trigger a global adjustment process and control the head-end pressure pump device to work if there is only one-way over-limit in all branch nodes and the proportion of one-way over-limit exceeds the first preset ratio. The mid-range controller is used to trigger a multi-region collaborative adjustment process and control the operation of the mid-range pressure pump device in multiple regions if there are bidirectional over-limits in all branch nodes, or the proportion of unidirectional over-limits is lower than the first preset ratio, or there are still areas with voltage over-limits after global adjustment. The end controller is used to control the end pump device at the household node to operate if the voltage exceeds the limit at the household node after adjustment by the first-end pump device and the middle-end pump device.

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