Method and system for controlling low-voltage ride-through of network construction type energy storage converter and computer equipment

Abstract

The invention relates to the technical field of voltage control, and particularly discloses a low-voltage ride-through control method and system for a network construction type energy storage converter and computer equipment. The method comprises the following steps: firstly, acquiring a node distance between a power grid fault node and an energy storage converter, judging whether the node distance exceeds a preset distance, if so, performing equal-proportion segmentation on the node distance to obtain a plurality of segmented power grid distances, and acquiring a segmented node between every two segmented power grid distances; and obtaining apparent power and resistance value corresponding to the segmentation nodes, obtaining a power grid recovery adjustment proportion according to the resistance value and the apparent power, carrying out ring topological structure networking on a plurality of segmentation power grid distances, and carrying out power grid recovery control on the ring topological structure networking according to the power grid recovery adjustment proportion at the same time. Therefore, the distance can be shortened through simultaneous closing control of the head and tail nodes, and the problem that normal operation of the energy storage converter is delayed due to slow recovery of a power grid caused by the transmission distance of a fault wire in the low-voltage ride-through control process is solved.

Description

Technical Field

[0001] The present invention relates to the technical field of voltage control, and in particular to a low-voltage ride-through control method and system for a network-forming energy storage converter and a computer device. Background Art

[0002] Low-voltage ride-through means that when the grid voltage undergoes a short-term drop or fault, power equipment (such as converters, inverters, etc.) can continue to operate stably and quickly return to the normal operating state after the voltage returns to normal. For a network-forming energy storage converter, its design must ensure that during a short-term grid voltage fault, the converter will not be disconnected or trip due to the voltage drop, thereby ensuring the stability of the power system and the reliability of the energy storage system.

[0003] However, in the process of low-voltage ride-through control of existing energy storage converters, the grid recovery is slow due to the transmission distance of the faulty wire (as the transmission distance of the faulty wire increases, the power loss during power transmission will increase significantly. According to electrical principles, the line resistance consumes electrical energy, and the long-distance transmission exacerbates the cumulative effect of the resistance, resulting in a large amount of electrical energy dissipated in the form of heat, and the power effectively transmitted to the grid decreases. At the same time, the reactance of the long-distance transmission line will also cause a voltage drop, making the voltage at the end of the grid much lower than the normal value, affecting the normal operation of grid equipment). Therefore, a low-voltage ride-through control method and system for a network-forming energy storage converter and a computer device are needed to solve the above problems. Summary of the Invention

[0004] The purpose of the present invention is to provide a low-voltage ride-through control method and system for a network-forming energy storage converter and a computer device to solve the technical problems mentioned in the above background art.

[0005] To achieve the above purpose, the present invention provides the following technical solutions:

[0006] A low-voltage ride-through control method for a network-forming energy storage converter includes:

[0007] Obtain the node distance between the grid fault node and the energy storage converter;

[0008] Judge whether the node distance exceeds a preset distance;

[0009] If the node distance exceeds the preset distance, proportionally divide the node distance to obtain multiple divided grid distances;

[0010] Obtain the dividing nodes between every two of the divided grid distances, and obtain the grid node information corresponding to the dividing nodes, where the grid node information includes grid power characteristic information and grid resistance characteristic information;

[0011] Obtain the active power and reactive power according to the grid power characteristic information, and obtain the apparent power according to the active power and the reactive power;

[0012] Obtain the impedance value according to the grid resistance characteristic information, and obtain the grid restoration adjustment ratio according to the impedance value and the apparent power;

[0013] Network the multiple divided grid distances into a ring topology structure, and screen the starting and ending points for the multiple divided nodes according to the ring topology structure networking to obtain the starting divided node and the ending divided node;

[0014] Use the starting divided node and the ending divided node to simultaneously perform grid restoration control on the ring topology structure networking according to the grid restoration adjustment ratio.

[0015] Preferably, the step of obtaining the active power and reactive power according to the grid power characteristic information, and obtaining the apparent power according to the active power and the reactive power includes:

[0016] Obtain the grid voltage and grid current according to the grid power characteristic information;

[0017] Obtain the voltage waveform of the grid voltage based on an oscilloscope;

[0018] Obtain the current waveform of the grid current based on an oscilloscope;

[0019] Obtain the phase angle of the voltage-current wave according to the voltage waveform and the current waveform, and calculate the active and reactive power according to the grid voltage, the grid current and the phase angle, where the calculation formula is:

[0020] P(G) = V * I * cos(θ);

[0021] Wherein, P(G) represents the active and reactive power, V represents the grid voltage, I represents the grid current, and θ represents the phase angle;

[0022] Calculate the reactive power according to the grid voltage, the grid current and the phase angle, where the calculation formula is:

[0023] P(W) = V * I * sin(θ);

[0024] Wherein, P(W) represents the reactive power, V represents the grid voltage, I represents the grid current, and θ represents the phase angle;

[0025] Calculate the apparent power according to the active power and the reactive power, where the calculation formula is:

[0026]

[0027] Among them, P(s) represents apparent power, P(G) represents active and reactive power, and P(W) represents reactive power.

[0028] As a priority, the step of obtaining the impedance value according to the grid resistance characteristic information and obtaining the grid restoration adjustment ratio according to the impedance value and the apparent power includes:

[0029] Obtain the inductive reactance and capacitive reactance in the power grid according to the grid resistance characteristic information, and calculate the reactance value according to the inductive reactance and the capacitive reactance;

[0030] Calculate the impedance value according to the reactance value and the preset resistance value;

[0031] Obtain the frequency fluctuation diagram of the power grid based on the oscilloscope, obtain the response time when the frequency fluctuation peak drops to the preset reference frequency according to the frequency fluctuation diagram, and use the response time as the adjustment factor;

[0032] Calculate the grid restoration adjustment ratio according to the impedance value, the apparent power and the, where the calculation formula is:

[0033]

[0034] Among them, B(L) represents the grid restoration adjustment ratio, P(W) represents reactive power, K(z) represents the impedance value, and K represents the adjustment factor.

[0035] As a priority, the step of forming a ring topology network with multiple divided grid distances includes:

[0036] Obtain the path start point and path end point of each divided grid distance according to the multiple divided grid distances;

[0037] Sort the multiple path start points and multiple path end points in ascending order of the path number to obtain a distance-number table;

[0038] Connect each path start point to two adjacent path end points in the order of the distance-number table until the start and end path start points and path end points are closed and connected, and a ring topology network is obtained.

[0039] As a priority, the step of screening the start and end points of multiple divided nodes according to the ring topology network to obtain the start divided node and the end divided node includes:

[0040] Obtain the first position of the grid fault node in the ring topology network, and use the first position as the start divided node;

[0041] Obtain multiple path spacings based on the starting segmentation node and the remaining multiple segmentation nodes, and perform ascending sorting on the multiple path spacings to obtain an ascending path spacing sorting table;

[0042] Extract the end path spacing according to the ascending path spacing sorting table, and use the end path spacing as the end segmentation node.

[0043] As a priority, the step of performing power grid restoration control on the ring topology network simultaneously according to the power grid restoration adjustment ratio by the starting segmentation node and the end segmentation node includes:

[0044] Perform low-voltage ride-through control on the reactive power and resistance value of the starting segmentation node based on the power grid restoration adjustment ratio to obtain a first control node;

[0045] Perform low-voltage ride-through control on the reactive power and resistance value of the end segmentation node based on the power grid restoration adjustment ratio to obtain a second control node;

[0046] Use the first control node and the second control node as two starting control nodes at the same time, and start from the two starting control nodes to perform simultaneous approaching adjustment on the multiple segmentation nodes in the ring topology network until power grid restoration control is achieved.

[0047] This application also provides a grid-forming energy storage converter low-voltage ride-through control system, including:

[0048] A first acquisition module for acquiring the node distance between the power grid fault node and the energy storage converter;

[0049] A first judgment module for judging whether the node distance exceeds a preset distance;

[0050] If the node distance exceeds the preset distance, equally divide the node distance to obtain multiple segmented power grid distances;

[0051] A second acquisition module for acquiring the segmentation nodes between every two of the segmented power grid distances and acquiring the grid node information corresponding to the segmentation nodes, where the grid node information includes grid power characteristic information and grid resistance characteristic information;

[0052] A third acquisition module for acquiring the active power and reactive power according to the grid power characteristic information, and acquiring the apparent power according to the active power and the reactive power;

[0053] A fourth acquisition module for acquiring the resistance value according to the grid resistance characteristic information, and acquiring the power grid restoration adjustment ratio according to the resistance value and the apparent power;

[0054] The first networking module is used to form a ring topology network for multiple of the divided grid distances, and screen the starting and ending points of multiple of the divided nodes according to the ring topology network to obtain a starting divided node and an ending divided node;

[0055] The first control module is used to simultaneously perform grid restoration control on the ring topology network according to the grid restoration adjustment ratio of the starting divided node and the ending divided node.

[0056] Preferably, the third acquisition module includes:

[0057] The first acquisition unit is used to acquire grid voltage and grid current according to the grid power characteristic information;

[0058] The second acquisition unit is used to acquire the voltage waveform of the grid voltage based on an oscilloscope;

[0059] The third acquisition unit is used to acquire the current waveform of the grid current based on an oscilloscope;

[0060] The fourth acquisition unit is used to acquire the phase angle of the voltage-current wave according to the voltage waveform and the current waveform, and calculate the active and reactive power according to the grid voltage, the grid current and the phase angle. The calculation formula is:

[0061] P(G) = V * I * cos(θ);

[0062] where P(G) represents the active and reactive power, V represents the grid voltage, I represents the grid current, and θ represents the phase angle;

[0063] The first calculation unit is used to calculate the reactive power according to the grid voltage, the grid current and the phase angle. The calculation formula is:

[0064] P(W) = V * I * sin(θ);

[0065] where P(W) represents the reactive power, V represents the grid voltage, I represents the grid current, and θ represents the phase angle;

[0066] The second calculation unit is used to calculate the apparent power according to the active power and the reactive power. The calculation formula is:

[0067]

[0068] where P(s) represents the apparent power, P(G) represents the active and reactive power, and P(W) represents the reactive power.

[0069] The present application also provides a computer device, including a memory and a processor, wherein the memory stores a computer program, and the processor implements the steps of the above method when executing the computer program.

[0070] The present application also provides a computer-readable storage medium on which a computer program is stored. When the computer program is executed by a processor, the steps of the above method are implemented.

[0071] The beneficial effects of the present application are as follows: the present invention first obtains the node distance between the grid fault node and the energy storage converter, and then determines whether the node distance exceeds the preset distance. If the node distance exceeds the preset distance, the node distance is divided into equal proportions to obtain a plurality of divided grid distances, and then the divided nodes between every two divided grid distances are obtained, and the grid power characteristic information and grid resistance characteristic information corresponding to the divided nodes are obtained, and then the active power and reactive power are obtained according to the grid power characteristic information, and the apparent power is obtained according to the active power and the reactive power, and then the impedance value is obtained according to the grid resistance characteristic information. , and obtain the grid recovery adjustment ratio according to the impedance value and the apparent power, then network the multiple split grid distances into a ring topology structure, screen the start and end points of the multiple split nodes according to the ring topology structure networking, and obtain the start split node and the end split node, and finally, control the grid recovery of the ring topology structure networking with the start split node and the end split node according to the grid recovery adjustment ratio, so that the distance can be shortened by controlling the head and tail nodes at the same time, and the problem of slow grid recovery and delayed normal operation of the energy storage converter during low voltage ride-through control due to the transmission distance of the faulty wire can be avoided. BRIEF DESCRIPTION OF THE DRAWINGS

[0072] Figure 1 The figure is a schematic diagram of a method flow of an embodiment of the present application.

[0073] Figure 2 A schematic diagram of the system structure of an embodiment of the present application.

[0074] Figure 3 A schematic diagram of the internal structure of a computer device according to an embodiment of the present application.

[0075] The realization of the purpose, functional features and advantages of this application will be further explained in conjunction with embodiments and with reference to the accompanying drawings. DETAILED DESCRIPTION

[0076] It should be understood that the specific embodiments described herein are only used to explain the present invention, and are not used to limit the present invention.

[0077] like Figures 1-3As shown, the present application provides a low-voltage ride-through control method for a network-forming energy storage converter, including:

[0078] S1. Obtain the node distance between the grid fault node and the energy storage converter;

[0079] S2. Determine whether the node distance exceeds a preset distance;

[0080] If the node distance exceeds the preset distance, proportionally divide the node distance to obtain multiple divided grid distances;

[0081] S3. Obtain the dividing nodes between every two of the divided grid distances, and obtain the grid node information corresponding to the dividing nodes, where the grid node information includes grid power characteristic information and grid resistance characteristic information;

[0082] S4. Obtain the active power and reactive power according to the grid power characteristic information, and obtain the apparent power according to the active power and the reactive power;

[0083] S5. Obtain the impedance value according to the grid resistance characteristic information, and obtain the grid recovery regulation ratio according to the impedance value and the apparent power;

[0084] S6. Network the multiple divided grid distances into a ring topology structure, screen the starting and ending points of the multiple dividing nodes according to the ring topology structure networking, and obtain the starting dividing node and the ending dividing node;

[0085] S7. Simultaneously perform grid recovery control on the ring topology structure networking according to the starting dividing node and the ending dividing node in accordance with the grid recovery regulation ratio.

[0086] As described in the above steps S1 - S7, since the existing energy storage converters will cause the power grid to recover slowly due to the transmission distance of the faulty wires during the low - voltage ride - through control, which in turn delays the normal operation of the power grid due to the recovery, and at the same time, since distance is one of the key factors affecting the power grid recovery, clarifying the distance can distinguish the fault scenarios and determine whether to divide the distance and adopt special control means subsequently. This is the primary link in constructing the entire control system. Therefore, the present invention first obtains the node distance between the power grid fault node and the energy storage converter. Accurately obtaining this distance is the cornerstone of subsequent operations. Among them, the power grid fault node refers to the physical fault point detected by the system, and the node distance between the power grid fault node and the energy storage converter is the faulty line that needs to be restored. The power grid characteristics vary greatly at different distances. For example, long distances are likely to cause large voltage drops and more power losses, affecting the low - voltage ride - through effect. This distance information can help judge the scope and degree of the fault impact, provide a key basis for formulating targeted strategies, make the control method fit the actual power grid conditions, and ensure the system stability. Since the preset distance is an important benchmark for measuring the severity of the fault and the selection of control strategies, it is possible to judge whether the node distance exceeds the preset distance. If the node distance exceeds the preset distance, the node distance is divided proportionally to obtain multiple divided power grid distances. Furthermore, through this judgment, the control process is split, avoiding resource waste or insufficient control caused by unified processing of all faults, dealing with faults hierarchically according to the distance, enhancing the flexibility and adaptability of the method. Then, the divided nodes between every two of the divided power grid distances are obtained, and the power grid node information corresponding to the divided nodes is obtained. The principle of the corresponding node information after division is as follows: During the operation of the power grid, when the node distance is divided proportionally, these divided points have clear physical positions on the power grid line, and the power grid nodes are the existing positions in the power grid with electrical connections and specific electrical characteristics. Although the divided nodes are generated based on distance division, due to the continuity and electrical relevance of the power grid line itself, the divided nodes must have a corresponding relationship with the existing nodes in the power grid. From the perspective of electrical connection, the power grid is a network composed of numerous electrical devices and lines connected together, and electric energy is transmitted in it along a certain electrical path. When the distance between the fault node and the energy storage converter is divided, these divided points are actually divided on the original power grid line. They will inherit the electrical characteristics of the location where they are located and have a close connection with the surrounding power grid nodes. For example, after the distance is divided on a transmission line, the electrical parameters such as voltage and current at the location of the divided node will be affected by the adjacent power grid nodes, and at the same time, they will also have a reverse effect on the electrical state of the adjacent nodes. This mutual influence and association make the divided nodes form a corresponding relationship with the power grid nodes at the electrical level. Among them, the power grid node information includes the power grid power characteristic information and the power grid resistance characteristic information. In this way, after the long distance is divided, the complex power grid line can be refined into multiple sub - intervals.It is convenient for in-depth analysis of the characteristics of power grids in each interval, such as local voltage changes and power distribution differences, making the control more targeted. At the same time, it reduces the complexity of the problem, converts the overall control into a combination of multiple local controls, which is conducive to accurately adjusting the reactive power and voltage in each interval and improving the control effect. In the operation of the power grid, power and resistance are the key factors affecting the power grid recovery. The balance of the power grid power determines the matching degree of power supply and demand, which is directly related to the stability of the power grid frequency and voltage; while the power grid resistance affects the current transmission and power loss, and acts on the power grid voltage. These two are intertwined and jointly shape the recovery process of the power grid after a fault or abnormality. Furthermore, the power characteristic information can reflect the energy conversion and transmission efficiency and the load supply-demand balance, and the resistance characteristic information reveals the line power loss and the degree of current obstruction. Accurately obtaining them can comprehensively master the electrical characteristics of the power grid, provide core data for accurately calculating the active and reactive powers and subsequent control parameters, and ensure that the control strategy closely fits the actual operating state of the power grid. Since the active, reactive, and apparent powers are the core indicators of power grid operation, accurately calculating them can deeply analyze the power flow of the power grid and provide a direct basis for formulating control strategies. Therefore, the active power and reactive power can be obtained according to the power grid power characteristic information, and the apparent power can be obtained according to the active power and the reactive power. The active power is related to the effective utilization of electric energy and the work ability of equipment, and the reactive power affects the voltage quality and the stability of the power grid. Calculating the apparent power can comprehensively evaluate the power transmission scale and ability of the power grid, provide a key quantitative indicator for judging the power grid load level, power balance and subsequent determination of control strategies such as reactive power compensation, and ensure the stable and economic operation of the power grid. Then, the distances of multiple divided power grids are networked into a ring topology structure, and then the start and end points of multiple divided nodes are screened according to the ring topology structure networking to obtain the start divided node and the end divided node. In this way, the resistance value can reflect the current obstruction characteristics of the power grid, and together with the apparent power, it determines the power grid recovery regulation ratio, accurately guiding the reactive power compensation amount and the voltage regulation amplitude, ensuring that under different power grid conditions, the output of the energy storage converter can effectively support the power grid recovery and maintain voltage stability. Finally, the start divided node and the end divided node are used to simultaneously perform power grid recovery control on the ring topology structure networking according to the power grid recovery regulation ratio. In this way, the ring topology networking changes the traditional linear power grid analysis perspective, explores new connection relationships and synergistic effects between divided nodes. Clearly defining the start and end nodes defines the control range and direction, and multi-path power transmission and cooperative control can be realized in the ring structure. For example, when a fault occurs, the electric energy can bypass the fault point and transmit circuitously, enhancing the redundancy and reliability of the power grid, optimizing the power grid recovery path and efficiency. At the same time, the simultaneous approach control of the head and tail nodes can shorten the distance and avoid the problem that the energy storage converter will delay the normal operation due to the slow power grid recovery caused by the transmission distance of the faulty wire during the low-voltage ride-through control.

[0087] In one embodiment, step S3 of obtaining the active power and the reactive power according to the grid power characteristic information and obtaining the apparent power according to the active power and the reactive power includes:

[0088] S401. Obtain the grid voltage and the grid current according to the grid power characteristic information;

[0089] S402. Obtain the voltage waveform of the grid voltage based on an oscilloscope;

[0090] S403. Obtain the current waveform of the grid current based on an oscilloscope;

[0091] S404. Obtain the phase angle of the voltage-current wave according to the voltage waveform and the current waveform, and calculate the active and reactive power according to the grid voltage, the grid current and the phase angle, where the calculation formula is:

[0092] P(G) = V * I * cos(θ);

[0093] Wherein, P(G) represents the active and reactive power, V represents the grid voltage, I represents the grid current, and θ represents the phase angle;

[0094] S405. Calculate the reactive power according to the grid voltage, the grid current and the phase angle, where the calculation formula is:

[0095] P(W) = V * I * sin(θ);

[0096] Wherein, P(W) represents the reactive power, V represents the grid voltage, I represents the grid current, and θ represents the phase angle;

[0097] S406. Calculate the apparent power according to the active power and the reactive power, where the calculation formula is:

[0098]

[0099] Wherein, P(s) represents the apparent power, P(G) represents the active and reactive power, and P(W) represents the reactive power.

[0100] As described in the above steps S401 - S406, the present invention first obtains the grid voltage and grid current based on the grid power characteristic information. Since the grid voltage and current are the basic physical quantities reflecting the grid operation state, obtaining them can intuitively present the electric energy transmission intensity and load condition of the grid. At the same time, accurate voltage and current data are the cornerstone for subsequent accurate analysis of power and other electrical parameters, providing key clues for judging whether the grid is in a normal operation state, whether there are abnormal fluctuations or potential fault hazards, and being the primary link to ensure the stable power supply of the grid and the safe operation of equipment. Then, based on the oscilloscope, the voltage waveform of the grid voltage is obtained. The voltage waveform obtained by the oscilloscope can visually display the dynamic change of voltage over time. Compared with a single voltage value, the waveform can clearly present the fluctuation law, frequency characteristics of the voltage, and whether there are instantaneous mutations or interferences, etc. This helps to deeply analyze the transient process of the grid, such as voltage sags, swells, or oscillations, etc., providing an intuitive basis for accurately identifying abnormal events in the grid and evaluating their potential impact on the grid stability. Then, based on the oscilloscope, the current waveform of the grid current is obtained. The current waveform can directly reflect the dynamic change process of the current. And by analyzing the current waveform, the dynamic characteristics of the load, the current harmonic components, and the impact current in the grid can be understood. Combining with the voltage waveform can accurately judge key parameters such as the power factor and reactive power demand of the grid, which is of great significance for optimizing the grid power configuration, improving the power utilization efficiency, and ensuring the safe and stable operation of the grid, and is a key link for comprehensively analyzing the electrical characteristics of the grid. Then, the phase angle of the voltage - current wave is obtained according to the voltage waveform and the current waveform, and the active and reactive powers are calculated based on the grid voltage, the grid current, and the phase angle. Among them, the phase angle is one of the core elements of grid power analysis. By accurately obtaining the phase angle of the voltage - current wave and combining with the voltage and current amplitudes, the active power and reactive power can be accurately calculated. The active power determines the actual work - doing ability of the grid and the effective utilization degree of electric energy, and the reactive power affects the voltage quality and stability of the grid. Accurately calculating these power parameters can quantitatively evaluate the energy conversion and transmission efficiency of the grid, providing key decision - making basis for judging the grid load characteristics, optimizing power distribution, and taking control measures such as reactive power compensation, and is a key step to ensure the economic and stable operation of the grid. Then, the reactive power is calculated based on the grid voltage, the grid current, and the phase angle. Among them, although the reactive power does not directly do work in the grid, it plays a key role in maintaining voltage stability and ensuring the normal operation of power equipment. And by accurately calculating the reactive power, the supply - demand balance status of the grid reactive power can be clarified, and problems of reactive power shortage or excess can be found in time.This helps to take reactive power compensation measures specifically, such as putting into operation equipment like capacitor banks or reactors, optimizing the grid voltage distribution, reducing line losses, improving the power supply quality and stability of the grid, ensuring the reliable operation of the power system. It is an important parameter for regulating the grid. Then, the reactive power is calculated based on the grid voltage, the grid current, and the phase angle. Among them, although reactive power does not directly do work in the grid, it plays a crucial role in maintaining voltage stability and ensuring the normal operation of power equipment. Accurately calculating reactive power can clarify the supply-demand balance of reactive power in the grid and promptly detect problems of reactive power shortage or excess. This helps to take reactive power compensation measures specifically, such as putting into operation equipment like capacitor banks or reactors, optimizing the grid voltage distribution, reducing line losses, improving the power supply quality and stability of the grid, ensuring the reliable operation of the power system. Finally, the apparent power is calculated based on the active power and the reactive power. Through the apparent power, the overall scale and capacity of power transmission in the grid can be comprehensively reflected, which is an important indicator for measuring the grid capacity demand and load level. Calculating the apparent power can comprehensively evaluate the power transmission state of the grid, providing a key reference for judging whether the grid is overloaded, whether the equipment capacity is matched, and planning grid expansion, etc. Combining the proportional relationship between the active power and the reactive power can also analyze the power factor of the grid, further optimizing the grid operation efficiency, ensuring the safe and economic operation of the grid, and providing a basic basis for the low-voltage ride-through regulation of the grid by the energy storage converter.

[0101] In one embodiment, the step S5 of obtaining the impedance value according to the grid resistance characteristic information and obtaining the grid restoration adjustment ratio according to the impedance value and the apparent power includes:

[0102] S501. Obtain the inductive reactance and capacitive reactance in the grid according to the grid resistance characteristic information, and calculate the reactance value according to the inductive reactance and the capacitive reactance;

[0103] S502. Calculate the impedance value according to the reactance value and a preset resistance value;

[0104] S503. Obtain the frequency fluctuation graph of the grid based on an oscilloscope, obtain the response time when the frequency fluctuation peak drops back to a preset reference frequency according to the frequency fluctuation graph, and use the response time as an adjustment factor;

[0105] S504. Calculate the grid restoration adjustment ratio according to the impedance value, the apparent power, and the, where the calculation formula is:

[0106]

[0107] Among them, B(L) represents the grid restoration adjustment ratio, P(W) represents the reactive power, K(z) represents the impedance value, and K represents the adjustment factor.

[0108] As described in the above steps S501 - S504, the present invention first obtains the inductive reactance and capacitive reactance in the power grid according to the power grid resistance characteristic information, and calculates the reactance value according to the inductive reactance and the capacitive reactance. Among them, the inductive reactance and capacitive reactance in the power grid are the key factors affecting current transmission and voltage distribution. Obtaining them and calculating the reactance value can accurately quantify the impedance characteristics of the power grid to alternating current. This helps to deeply analyze the power transmission efficiency and stability of the power grid under different working conditions, and provides the core electrical parameter basis for accurately evaluating the electrical state during power grid faults and formulating targeted control strategies in the follow - up. Then, calculate the impedance value according to the reactance value and the preset resistance value. Among them, the impedance value comprehensively reflects the impedance effect of the combined action of the power grid resistance and reactance on the current. Accurately calculating the impedance value can comprehensively evaluate the impedance degree of the power grid to power transmission under fault or abnormal working conditions, and provide key quantitative indicators for judging the difficulty of power grid voltage recovery, current regulation requirements, etc. This is an important basis for accurately regulating the power grid, directly related to whether the subsequent control strategy can effectively overcome the power grid impedance and achieve stable recovery. Then, based on the oscilloscope, obtain the frequency fluctuation diagram of the power grid, and obtain the response time when the frequency fluctuation peak drops to the preset reference frequency according to the frequency fluctuation diagram, and use the response time as the adjustment factor. The dynamic change process of the power grid frequency can be visually presented through the power grid frequency fluctuation diagram. Obtaining the response time when the frequency fluctuation peak drops to the preset reference frequency as the adjustment factor can accurately measure the dynamic recovery ability of the power grid after being disturbed. This factor reflects the inertia and regulation characteristics of the power grid. In power grid control, it is the key basis for adjusting the intensity and rhythm of the control strategy to ensure that the control measures are adapted to the actual recovery ability of the power grid, effectively avoiding over - control or under - control, and ensuring the stable transition of the power grid to the normal operation state. Finally, calculate the power grid recovery adjustment ratio according to the impedance value, the apparent power, and. Among them, the power grid recovery adjustment ratio is the core parameter guiding power grid recovery control. It comprehensively considers various factors such as the impedance value, apparent power, and adjustment factor, accurately determines the reactive power compensation intensity and voltage regulation amplitude that the energy storage converter should adopt under specific power grid working conditions, and at the same time can ensure that the output of the energy storage converter accurately matches the power grid recovery demand, effectively supporting the power grid voltage recovery, maintaining power balance, ensuring the rapid and stable recovery of the power grid to normal operation after a fault, and providing a basis for the energy storage converter to regulate the power grid during low - voltage ride - through.

[0109] In one embodiment, step S6 of forming a ring - shaped topology network with multiple segmented power grid distances includes:

[0110] S601. Obtain the path start point and path end point of each of the segmented power grid distances according to the multiple segmented power grid distances;

[0111] S602. Sort the multiple path start points and the multiple path end points in ascending order of the path numbers to obtain a distance-number table;

[0112] S603. Connect each path start point with two adjacent path end points in the order of the sequence in the distance-number table until the connection between the head and tail path start points and path end points is completed, so as to obtain a ring-shaped topology network.

[0113] As described in the above steps S601 - S603, the present invention first obtains the path start points and path end points of each of the split power grid distances according to the multiple split power grid distances. Among them, the path start points and path end points are the basic elements for constructing a ring-shaped topology. Furthermore, the boundary of each section of the power grid line can be clearly defined through the basic elements, providing a basic framework for the subsequent construction of the topology. For example, in a system with multiple split power grid distances, clarifying the start and end points of each section of the line allows us to clearly know the possible power transmission paths and boundary ranges, which helps us analyze the flow and distribution of electric energy between different line segments. At the same time, it can also avoid the power grid regulation disconnection caused by a single line through the ring-shaped topology network. Then, sort the multiple path start points and the multiple path end points in ascending order of the path numbers to obtain a distance-number table. By numbering and sorting the path start points and end points, an ordered logical relationship is established. This makes the originally disordered path information become ordered, facilitating subsequent processing and operations. The sorted distance-number table provides a clear operation sequence for the subsequent connection operation, avoiding problems such as unreasonable topology caused by chaotic and random connections. Finally, connect each path start point with two adjacent path end points in the order of the sequence in the distance-number table until the connection between the head and tail path start points and path end points is completed, so as to obtain a ring-shaped topology network. The ring-shaped topology formed in this way has many advantages in the power grid. For example, it can provide redundant power transmission paths. When a certain section of the line fails, the electric energy can be transmitted through other paths in the ring, improving the reliability and fault tolerance of the power grid and ensuring the continuous power supply of the power system. At the same time, by connecting the head and tail path start points and end points, the integrity and closure of the topology are ensured, forming a complete ring. And the ring-shaped topology can better achieve the balanced distribution of power because the electric energy can flow bidirectionally on the ring and can flexibly adjust the power flow direction according to the load conditions of different nodes, improving the flexibility and resource utilization efficiency of the power grid. At the same time, the ring-shaped topology network changes the single line of the existing power grid, and when a power grid failure occurs, the electric energy can bypass the fault point and transmit circuitously, greatly enhancing the redundancy and reliability of the power grid, optimizing the power grid recovery path and efficiency, and providing a strong guarantee for the stable operation of the power grid.

[0114] In one embodiment, step S6 of screening the starting and ending points of multiple said segmentation nodes according to the networking of the ring topology structure to obtain a starting segmentation node and an ending segmentation node includes:

[0115] S604. Obtain the first position of the power grid fault node in the networking of the ring topology structure, and use the first position as the starting segmentation node;

[0116] S605. Obtain multiple path distances based on the starting segmentation node and the remaining multiple said segmentation nodes, and perform an increasing sorting on the multiple path distances to obtain an increasing path distance sorting table;

[0117] S606. Extract the last path distance according to the increasing path distance sorting table, and use the last path distance as the ending segmentation node.

[0118] As described in steps S604 - S606 above, the present invention first obtains the first position of the power grid fault node in the networking of the ring topology structure, and uses the first position as the starting segmentation node. By obtaining the first position of the power grid fault node in the networking of the ring topology structure and using it as the starting segmentation node, the starting point of the power grid restoration control is clarified. This enables subsequent control operations to be carried out targeted from the key position in the fault - affected area. Just like determining the starting point of a rescue operation on a map, it provides a clear direction for the entire power grid restoration process, helps to concentrate resources and efforts to effectively intervene in the fault area, improves the efficiency and accuracy of power grid restoration. Then, multiple path distances are obtained based on the starting segmentation node and the remaining multiple said segmentation nodes, and an increasing sorting is performed on the multiple path distances to obtain an increasing path distance sorting table. This can clearly present the distance relationship between each segmentation node and the starting point. This provides a data basis for further screening the ending segmentation node, and at the same time, it can also intuitively understand the length differences of different paths, which helps to find the node farthest from the starting point, so as to determine the position that can best represent the boundary of the entire control range, ensuring that the power grid restoration control can cover the widest area and avoid missing key nodes. Finally, the last path distance is extracted according to the increasing path distance sorting table, and the last path distance is used as the ending segmentation node. In this way, the ending segmentation node and the starting segmentation node jointly define the scope of the power grid restoration control. This ensures that in the ring topology structure, the control operation can cover all key nodes from near the fault point to the relatively farthest area, realizing the overall management and control of the entire power grid fault - affected area. Through clear scope definition, control resources can be reasonably allocated, avoiding situations of over - control or under - control, effectively improving the effect and speed of power grid restoration, and ensuring the stable operation of the power grid.

[0119] In one embodiment, step S7 of performing power grid restoration control on the ring topology network by simultaneously using the starting segmentation node and the ending segmentation node according to the power grid restoration adjustment ratio includes:

[0120] S701. Perform low-voltage ride-through control on the reactive power and resistance value of the starting segmentation node based on the power grid restoration adjustment ratio to obtain a first control node;

[0121] S702. Perform low-voltage ride-through control on the reactive power and resistance value of the ending segmentation node based on the power grid restoration adjustment ratio to obtain a second control node;

[0122] S703. Simultaneously use the first control node and the second control node as two starting control nodes, and start simultaneously approaching and adjusting multiple segmentation nodes in the ring topology network from the two starting control nodes until power grid restoration control is achieved.

[0123] As described in the above steps S701 - S703, the present invention first performs low - voltage ride - through control on the reactive power and resistance value of the starting segmentation node based on the grid restoration regulation ratio to obtain the first control node. In this way, the electrical parameters at the starting node can be precisely adjusted through the first control node. By adjusting the reactive power, the voltage quality near the starting node can be effectively improved, and the stability of the power grid can be maintained. According to the adjustment of the resistance value, the current transmission characteristics are optimized, power loss is reduced, and the efficient transmission and distribution of electric energy in the starting node area are ensured, laying a good foundation for subsequent grid restoration. Then, low - voltage ride - through control is performed on the reactive power and resistance value of the ending segmentation node based on the grid restoration regulation ratio to obtain the second control node. Similarly, low - voltage ride - through control is performed on the reactive power and resistance value of the ending segmentation node based on the grid restoration regulation ratio, which acts on another key boundary position of the power grid. Adjusting the reactive power of the ending node helps to stabilize the voltage at the end of the power grid and prevent the spread of voltage fluctuations in the edge area of the power grid. Optimizing the resistance value can ensure the smooth transmission of electric energy at the end of the power grid and avoid power loss or transmission obstruction caused by abnormal electrical parameters at the end. Cooperating with the starting node control, it forms an effective closed - loop for the entire power grid control range, strengthening the overall stability of the power grid. Finally, the first control node and the second control node are simultaneously used as two starting control nodes, and starting from the two starting control nodes, simultaneous approaching adjustments are made to multiple segmentation nodes in the ring - topology network until grid restoration control is achieved. By using the controlled first control node and second control node as starting control nodes and making simultaneous approaching adjustments to multiple segmentation nodes in the ring - topology network, coordinated control of multiple nodes is realized. During the adjustment process, each node dynamically adjusts the resistance value and apparent power according to the grid restoration regulation ratio. Among them, the resistance value comprehensively reflects the blocking effect of the combined action of the grid resistance and reactance on the current. When a power grid failure or abnormal operating condition occurs, accurately calculating the resistance value can comprehensively evaluate the degree of obstruction of the power grid to electric energy transmission. By adjusting the resistance value, the transmission path and magnitude of the current in the power grid can be changed. During the low - voltage ride - through control process, if a fault causes the current in a certain area to be too large or too small, resulting in voltage abnormalities, appropriately adjusting the resistance value can guide the reasonable distribution of the current, avoid local current overload or deficiency, and thus reduce the voltage drop or voltage fluctuation caused by unreasonable current flow, making the voltage tend to be stable. For example, when a short - circuit fault occurs, the line reactance may change, causing the current to increase sharply. At this time, reasonably adjusting the resistance value can limit the current increase and maintain voltage stability. At the same time, the apparent power is an important indicator for measuring the power grid capacity demand and load level, and it comprehensively reflects the transmission situation of active power and reactive power. When voltage abnormalities occur in the power grid, they are often related to the imbalance of power transmission. By analyzing and adjusting the apparent power, the power transmission state of the power grid can be comprehensively evaluated to determine whether the voltage problem is caused by excessive or insufficient active power, reactive power imbalance, or both.For example, if the apparent power is too large, it may mean that the power grid is overloaded, resulting in a voltage drop. At this time, measures need to be taken to adjust the power transmission scale, such as controlling the output power of the energy storage converter, so that the apparent power is restored to a reasonable range, thereby reducing the burden on the power grid, promoting the voltage to rise, and then through the resistance value and the apparent power, the electric energy can be efficiently transmitted and reasonably distributed in the ring structure, gradually narrowing the scope of the fault impact, accelerating the speed of the power grid to return to normal operation, effectively solving the problem of slow power grid recovery caused by the transmission distance of the faulty wire, and enhancing the self-healing ability and reliability of the power grid.

[0124] This application also provides a low-voltage ride-through control system for a grid-forming energy storage converter, including:

[0125] The first acquisition module 1 is used to acquire the node distance between the power grid fault node and the energy storage converter;

[0126] The first judgment module 2 is used to judge whether the node distance exceeds a preset distance;

[0127] If the node distance exceeds the preset distance, the node distance is equally divided to obtain multiple divided power grid distances;

[0128] The second acquisition module 3 is used to acquire the divided nodes between every two of the divided power grid distances and acquire the power grid node information corresponding to the divided nodes, where the power grid node information includes power grid power characteristic information and power grid resistance characteristic information;

[0129] The third acquisition module 4 is used to acquire the active power and reactive power according to the power grid power characteristic information and acquire the apparent power according to the active power and the reactive power;

[0130] The fourth acquisition module 5 is used to acquire the resistance value according to the power grid resistance characteristic information and acquire the power grid recovery regulation ratio according to the resistance value and the apparent power;

[0131] The first networking module 6 is used to perform ring topology networking on multiple divided power grid distances, screen the starting and ending points of multiple divided nodes according to the ring topology networking, and obtain the starting divided node and the ending divided node;

[0132] The first control module 7 is used to perform power grid recovery control on the ring topology networking simultaneously according to the starting divided node and the ending divided node according to the power grid recovery regulation ratio.

[0133] In one embodiment, the third acquisition module includes:

[0134] The first acquisition unit is used to acquire the power grid voltage and the power grid current according to the power grid power characteristic information;

[0135] A second acquisition unit, configured to acquire the voltage waveform of the grid voltage based on an oscilloscope;

[0136] A third acquisition unit, configured to acquire the current waveform of the grid current based on an oscilloscope;

[0137] A fourth acquisition unit, configured to acquire the phase angle of the voltage-current wave according to the voltage waveform and the current waveform, and calculate the active and reactive power according to the grid voltage, the grid current, and the phase angle, where the calculation formula is:

[0138] P(G) = V * I * cos(θ);

[0139] where P(G) represents the active and reactive power, V represents the grid voltage, I represents the grid current, and θ represents the phase angle;

[0140] A first calculation unit, configured to calculate the reactive power according to the grid voltage, the grid current, and the phase angle, where the calculation formula is:

[0141] P(W) = V * I * sin(θ);

[0142] where P(W) represents the reactive power, V represents the grid voltage, I represents the grid current, and θ represents the phase angle;

[0143] A second calculation unit, configured to calculate the apparent power according to the active power and the reactive power, where the calculation formula is:

[0144]

[0145] where P(s) represents the apparent power, P(G) represents the active and reactive power, and P(W) represents the reactive power.

[0146] The present invention further provides a computer device, including a memory and a processor, where the memory stores a computer program, and the processor executes the steps of the low-voltage ride-through control method for the grid-connected energy storage converter.

[0147] The present invention further provides a computer-readable storage medium, on which a computer program is stored, and the computer program is executed by a processor to implement the steps of the above-mentioned low-voltage ride-through control method for the grid-connected energy storage converter.

[0148] Those of ordinary skill in the art can understand that all or part of the processes in the methods of the above embodiments can be completed by instructing relevant hardware through a computer program. The computer program can be stored in a non-volatile computer-readable storage medium. When the computer program is executed, it can include the processes of the embodiments of the above methods. Among them, any reference to a memory, storage, database, or other medium provided in this application and used in the embodiments can include non-volatile and / or volatile memories. Non-volatile memory can include read-only memory (ROM), programmable ROM (PROM), electrically programmable ROM (EPROM), electrically erasable programmable ROM (EEPROM), or flash memory. Volatile memory can include random access memory (RAM) or external cache memory. By way of illustration and not limitation, RAM is available in many forms, such as static RAM (SRAM), dynamic RAM (DRAM), synchronous DRAM (SDRAM), double data rate SDRAM (SSRSDRAM), enhanced SDRAM (ESDRAM), synchronous link (Synchlink) DRAM (SLDRAM), Rambus direct RAM (RDRAM), direct memory bus dynamic RAM (DRDRAM), and Rambus dynamic RAM (RDRAM), etc.

[0149] It should be noted that in this article, the term "including", "comprising", or any other variant thereof is intended to cover non-exclusive inclusion, such that a process, apparatus, article, or method including a series of elements not only includes those elements but also includes other elements not expressly listed, or further includes elements inherent to such process, apparatus, article, or method. Without further limitation, an element defined by the statement "including one..." does not exclude the existence of additional identical elements in the process, apparatus, article, or method including that element.

[0150] The above are only the preferred embodiments of the present invention, and do not limit the patent scope of the present invention. Any equivalent structural or equivalent process transformation made by using the specification and drawings of the present invention, or directly or indirectly applied in other related technical fields, shall be equally included in the patent protection scope of the present invention.

Claims

1. A low-voltage ride-through control method for a network-forming energy storage converter, characterized in that, Including: Obtain the node distance between the grid fault node and the energy storage converter; Judge whether the node distance exceeds a preset distance; If the node distance exceeds the preset distance, proportionally divide the node distance to obtain multiple divided grid distances; Obtain the division nodes between every two of the divided grid distances, and obtain the grid node information corresponding to the division nodes, where the grid node information includes grid power characteristic information and grid resistance characteristic information; Obtain the active power and reactive power according to the grid power characteristic information, and obtain the apparent power according to the active power and the reactive power; Obtain the impedance value according to the grid resistance characteristic information, and obtain the grid restoration adjustment ratio according to the impedance value and the apparent power; Network the multiple divided grid distances into a ring topology structure, and screen the start and end points of the multiple division nodes according to the ring topology structure networking to obtain the start division node and the end division node; Simultaneously perform grid restoration control on the ring topology structure networking according to the start division node and the end division node according to the grid restoration adjustment ratio.

2. The low-voltage ride-through control method for a grid-forming energy storage converter according to claim 1, characterized in that, The step of obtaining the active power and reactive power according to the grid power characteristic information, and obtaining the apparent power according to the active power and the reactive power includes: Obtain the grid voltage and grid current according to the grid power characteristic information; Obtain the voltage waveform of the grid voltage based on an oscilloscope; Obtain the current waveform of the grid current based on an oscilloscope; Obtain the phase angle of the voltage-current wave according to the voltage waveform and the current waveform, and calculate the active and reactive power according to the grid voltage, the grid current and the phase angle, where the calculation formula is: P(G) = V * I * cos(θ); Where, P(G) represents the active and reactive power, V represents the grid voltage, I represents the grid current, and θ represents the phase angle; Calculate the reactive power according to the grid voltage, the grid current and the phase angle, where the calculation formula is: P(W) = V * I * sin(θ); Where, P(W) represents the reactive power, V represents the grid voltage, I represents the grid current, and θ represents the phase angle; Calculate the apparent power according to the active power and the reactive power, where the calculation formula is: Where, P(s) represents the apparent power, P(G) represents the active and reactive power, and P(W) represents the reactive power.

3. The low-voltage ride-through control method for a network-forming energy storage converter according to claim 1, characterized in that, The step of obtaining the impedance value according to the grid resistance characteristic information, and obtaining the grid restoration adjustment ratio according to the impedance value and the apparent power includes: Obtain the inductive reactance and capacitive reactance in the grid according to the grid resistance characteristic information, and calculate the reactance value according to the inductive reactance and the capacitive reactance; Calculate the impedance value according to the reactance value and the preset resistance value; Obtain the frequency fluctuation diagram of the grid based on an oscilloscope, and obtain the response time when the frequency fluctuation peak drops back to the preset reference frequency according to the frequency fluctuation diagram, and use the response time as the adjustment factor; Calculate the grid restoration adjustment ratio according to the impedance value, the apparent power and the calculation, where the calculation formula is: Among them, B(L) represents the grid restoration regulation ratio, P(W) represents the reactive power, K(z) represents the resistance value, and K represents the regulation factor.

4. The low-voltage ride-through control method for a network-forming energy storage converter according to claim 1, wherein The step of networking the multiple divided grid distances into a ring topology structure includes: Obtaining the path start point and path end point of each of the multiple divided grid distances according to the multiple divided grid distances; Sorting the multiple path start points and the multiple path end points in ascending order of the path number to obtain a distance-number table; Connecting each path start point with two adjacent path end points in the order of the distance-number table until the head and tail path start points and path end points are closed and connected, obtaining a ring topology structure network.

5. The low-voltage ride-through control method for a grid-forming energy storage converter according to claim 1, characterized in that The step of screening the start and end points of the multiple divided nodes according to the ring topology structure network to obtain the start divided node and the end divided node includes: Obtaining the first position of the grid fault node in the ring topology structure network and using the first position as the start divided node; Obtaining multiple path spacings according to the start divided node and the remaining multiple divided nodes, and performing an ascending sort on the multiple path spacings to obtain an ascending path spacing sort table; Extracting the last path spacing according to the ascending path spacing sort table and using the last path spacing as the end divided node.

6. The low-voltage ride-through control method for a grid-forming energy storage converter according to claim 1, characterized in that The step of simultaneously performing grid restoration control on the ring topology structure network according to the start divided node and the end divided node according to the grid restoration regulation ratio includes: Performing low-voltage ride-through control on the reactive power and resistance value of the start divided node based on the grid restoration regulation ratio to obtain a first control node; Performing low-voltage ride-through control on the reactive power and resistance value of the end divided node based on the grid restoration regulation ratio to obtain a second control node; Using the first control node and the second control node as two start control nodes at the same time, and starting from the two start control nodes to perform simultaneous approach adjustment on the multiple divided nodes in the ring topology structure network until grid restoration control is achieved.

7. A low voltage ride-through control system for a network-forming energy storage converter, characterized in that, It includes: A first acquisition module for acquiring the node distance between the grid fault node and the energy storage converter; A first judgment module for judging whether the node distance exceeds a preset distance; If the node distance exceeds the preset distance, equally dividing the node distance to obtain multiple divided grid distances; A second acquisition module for acquiring the divided nodes between every two of the divided grid distances and acquiring the grid node information corresponding to the divided nodes, where the grid node information includes grid power characteristic information and grid resistance characteristic information; A third acquisition module for acquiring the active power and reactive power according to the grid power characteristic information and acquiring the apparent power according to the active power and the reactive power; A fourth acquisition module for acquiring the resistance value according to the grid resistance characteristic information and acquiring the grid restoration regulation ratio according to the resistance value and the apparent power; The first networking module is used to network multiple of the segmented grid distances in a ring topology, and screen the starting and ending points of multiple of the segmented nodes according to the ring topology networking, so as to obtain a starting segmented node and an ending segmented node; The first control module is used to perform grid restoration control on the ring topology networking simultaneously for the starting segmented node and the ending segmented node according to the grid restoration adjustment ratio.

8. The low-voltage ride-through control system of the network-forming energy storage converter according to claim 7, characterized in that, The third acquisition module includes: The first acquisition unit is used to acquire grid voltage and grid current according to the grid power characteristic information; The second acquisition unit is used to acquire the voltage waveform of the grid voltage based on an oscilloscope; The third acquisition unit is used to acquire the current waveform of the grid current based on an oscilloscope; The fourth acquisition unit is used to acquire the phase angle of the voltage-current wave according to the voltage waveform and the current waveform, and calculate the active and reactive power according to the grid voltage, the grid current and the phase angle. The calculation formula is: P(G) = V * I * cos(θ); where, P(G) represents the active and reactive power, V represents the grid voltage, I represents the grid current, and θ represents the phase angle; The first calculation unit is used to calculate the reactive power according to the grid voltage, the grid current and the phase angle. The calculation formula is: P(W) = V * I * sin(θ); where, P(W) represents the reactive power, V represents the grid voltage, I represents the grid current, and θ represents the phase angle; The second calculation unit is used to calculate the apparent power according to the active power and the reactive power. The calculation formula is: where, P(s) represents the apparent power, P(G) represents the active and reactive power, and P(W) represents the reactive power.

9. A computer device, comprising a memory and a processor, the memory storing a computer program, characterized in that, When the processor executes the computer program, it implements the steps of the method according to any one of claims 1 to 6.

10. A computer-readable storage medium having a computer program stored thereon, characterized in that, When the computer program is executed by the processor, it implements the steps of the method according to any one of claims 1 to 6.

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