Optimal configuration method and device of magnetic resistance type dynamic voltage restorer

Abstract

The application provides an optimal configuration method and device of a magnetic resistance type dynamic voltage restorer, relates to the technical field of optimal configuration, and specifically comprises the following steps: obtaining historical voltage sag event data of a target distribution bus and electrical parameters of downstream load motors; screening a to-be-compensated event set based on the principle that the sag depth exceeds a load tolerance threshold and the duration is less than a critical stall time, and determining a compensation strategy according to the comparison result of the maximum phase jump angle and a threshold value; determining the maximum compensation voltage according to the maximum sag depth, determining the rated output current according to the load parameters, calculating the theoretical energy required for compensating the longest event based on the compensation strategy, determining the actual energy required in combination with the energy correction coefficient of the device topology, and finally generating an optimal configuration scheme based on the compensation strategy, the maximum compensation voltage, the rated output current and the actual energy required. The application realizes accurate mapping from grid measured data to device key parameters.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of optimal configuration, in particular to an optimal configuration method and device of a magnetic dynamic voltage restorer. BACKGROUND

[0002] Voltage sag is one of the most prominent power quality problems in distribution networks, mainly caused by line short-circuit faults, large-capacity motor starting, etc., and is characterized by a transient drop in supply voltage amplitude and possibly accompanied by phase jump. For the impact load motor connected downstream of the distribution bus, even a millisecond-level voltage sag may cause the controller to malfunction, the torque to drop sharply and the motor to stall, resulting in huge production losses. As a kind of efficient series compensation device, the magnetic dynamic voltage restorer (DVR) supports the voltage on the load side by injecting compensation voltage into the system, which is the key technology to solve this problem. However, the existing DVR configuration methods mainly focus on conventional loads, and have limitations for motor protection scenarios that need to cope with severe load impact and may be accompanied by phase jump: on the one hand, the critical stall characteristics of the motor and the time and space characteristics of the voltage sag event are not considered comprehensively, which may lead to overcapacity of the device or failure of protection; on the other hand, the traditional method does not take phase jump as the core criterion for strategy selection, which cannot optimize the energy throughput of the device while ensuring compensation effect, restricting its economy and reliability.

[0003] The above information disclosed in the background section is only intended to enhance the understanding of the background of the present disclosure, and thus it can include information that does not constitute the prior art known to those of ordinary skill in the art. SUMMARY

[0004] The present application aims to provide an optimal configuration method and device of a magnetic dynamic voltage restorer to solve the problems raised in the background.

[0005] To achieve the above-mentioned purpose, the present application provides the following technical solutions:

[0006] An optimal configuration method of a magnetic dynamic voltage restorer, comprising the following specific steps:

[0007] Step 1: Obtain the relevant data of historical voltage sag events of the target distribution bus node in the statistical period, including the sag depth, duration and phase jump angle of each voltage sag event, and obtain the electrical characteristic parameters of the load motor connected downstream of the bus, including rated power, rated voltage, power factor and critical stall time;

[0008] Step 2: Based on the relevant data and electrical characteristic parameters of historical voltage sag events, select voltage sag events whose sag depth exceeds the preset load tolerance threshold and whose duration is less than the critical stall time to form a set of events to be compensated. Calculate the maximum value of the absolute value of the phase transition angle of all voltage sag events in the set to determine the relationship between the maximum value and the preset threshold, thereby determining the compensation strategy.

[0009] Step 3: Based on the maximum sag depth in the set of events to be compensated, determine the maximum compensation voltage required by the magnetic reactive dynamic voltage restorer. Based on the electrical characteristic parameters of the load motor, determine the rated output current of the magnetic reactive dynamic voltage restorer. Based on the compensation strategy, calculate the theoretical energy required to compensate the voltage sag event with the longest duration in the set of events to be compensated. Based on the topology of the magnetic reactive dynamic voltage restorer, determine the energy correction coefficient to determine the actual energy required for DC side energy storage.

[0010] Step 4: Based on the compensation strategy, maximum compensation voltage, rated output current, and actual required energy, generate and output an optimized configuration scheme for the magnetic reactive dynamic voltage restorer.

[0011] Furthermore, the target distribution bus node is the upstream common connection point of the power supply circuit to which the load motor belongs;

[0012] The relevant data of the historical voltage sag events are obtained from the power quality monitoring system, and the statistical period is at least one year. The historical voltage sag event is defined as an event in which the root mean square voltage value drops to between 0.1 pu and 0.9 pu of the rated voltage and the duration is between 0.5 cycles and 60 cycles. pu represents the per-unit value and cycle represents a complete AC sine wave.

[0013] The phase jump angle is obtained by capturing the voltage waveform within a time window preceding the voltage sag event. This time window is denoted as... The average value of the fundamental positive-sequence voltage phase is calculated using a phase-locked loop as the reference phase; the voltage waveform is captured for a time window after the voltage sag event ends, and this time window is represented as... The average value of the fundamental positive-sequence voltage phase is calculated using a phase-locked loop as the phase after the transient shift; the difference between the reference phase and the phase after the transient shift is calculated to obtain the phase jump angle; wherein, This represents the start time of the voltage sag event. For a single power frequency cycle, This is the preset delay.

[0014] Further, the critical stall time is determined by a stall protection parameter set in a motor control unit of the load motor, and the rated angular velocity, the rated power and the total moment of inertia of the load motor are collected, the total moment of inertia is the sum of the moment of inertia of the rotor of the load motor and the equivalent moment of inertia of the mechanical equipment driven by the load motor converted to the motor shaft, and the critical stall time is calculated, and the calculation formula is as follows:

[0015]

[0016] wherein, is the critical stall time, is the total moment of inertia, is the rated angular velocity, is the critical stall acceleration, the critical stall acceleration is 80% of the rated angular velocity, is the rated power of the load motor.

[0017] Further, the determination of the set of events to be compensated specifically includes:

[0018] The set of events to be compensated is specifically represented as: wherein, represents the set of events to be compensated, is the voltage sag event index, is the sag depth index of the event, is the duration of the event, is the phase jump angle of the event, is the load tolerance threshold preset according to the impact load characteristics, represents the critical stall time of the load motor;

[0019] The absolute values of the phase jump angles of all voltage sag events in the set of events to be compensated are calculated, and the maximum value is screened out, if the maximum value is not greater than the preset phase jump judgment threshold, it is determined that there is no effective phase jump to be compensated, if the maximum value is greater than the preset phase jump judgment threshold, it is determined that there is effective phase jump to be compensated.

[0020] Further, the determination of the compensation strategy specifically includes:

[0021] If it is determined that there is no effective phase jump of compensation, an in-phase voltage compensation strategy is selected; the in-phase voltage compensation strategy refers to controlling the compensation voltage output by the magnetic dynamic voltage restorer to be in the same phase as the grid residual voltage; when the strategy is executed, the controller of the magnetic dynamic voltage restorer performs the following operations: the waveform of the grid residual voltage is obtained in real time, and the phase angle thereof is extracted through a phase-locked loop; the phase angle of the output voltage vector of the inverter unit of the magnetic dynamic voltage restorer is controlled to be synchronized with the phase angle, so as to meet the control target that the phase angle of the grid residual voltage waveform is in the same phase as the phase angle of the output voltage vector; the strategy is executed, so that the compensation voltage injected by the magnetic dynamic voltage restorer is used to raise the amplitude of the grid residual voltage, and the active power ratio in the output power of the magnetic dynamic voltage restorer is not less than 90%;

[0022] If it is determined that there is an effective phase jump of compensation, a minimum energy compensation strategy is selected; the minimum energy compensation strategy refers to controlling the compensation voltage output by the magnetic dynamic voltage restorer to be in quadrature with the load current; when the strategy is executed, the controller of the magnetic dynamic voltage restorer performs the following operations: the waveform of the load current is obtained in real time, and the phase angle thereof is calculated through a phase-locked loop; the phase angle of the output voltage vector of the inverter unit of the magnetic dynamic voltage restorer is controlled, so as to meet the control target that the phase difference between the phase angle of the load current waveform and the phase angle of the voltage vector is 90 degrees; the strategy is executed, so as to realize the minimization of energy throughput in the compensation process.

[0023] Further, the depths of voltage sag of all voltage sag events in the set of events to be compensated are compared to determine the maximum depth of the maximum value, and the maximum compensation voltage is calculated according to the maximum depth and the rated voltage; the maximum compensation voltage is the product of the maximum depth and the rated voltage;

[0024] The limiting requirement of the rated output current of the magnetic dynamic voltage restorer is preset, that is, not less than the maximum operating current of the load motor, and is determined by the following formula:

[0025]

[0026] wherein, I is the rated output current of the magnetic dynamic voltage restorer, P is the rated power of the load motor, U is the rated voltage of the load motor, cos is the rated power factor of the load motor, is the rated impedance angle of the load motor;

[0027] The required theoretical energy based on the compensation strategy specifically includes:

[0028] If the selected compensation strategy is the in-phase voltage compensation strategy, the theoretical energy required for compensating the target event is calculated as follows:

[0029]

[0030] wherein, the theoretical energy required for compensating the target event when the in-phase voltage compensation strategy is selected, the compensation voltage of the target event, the load motor current; wherein, , , the target event represents the depth of the sag, the target event represents the duration of the sag;

[0031] If the selected compensation strategy is the minimum energy compensation strategy, the theoretical energy required for compensating the target event is calculated as follows:

[0032]

[0033] wherein, the theoretical energy required for compensating the target event when the minimum energy compensation strategy is selected, the phase jump angle of the target event, the duration of the target event.

[0034] Further, the actual required energy of the DC side energy storage is determined in particular as follows:

[0035] According to the topology of the device, the energy correction coefficient is determined to calculate the actual required energy of the DC side energy storage, and the formula is as follows:

[0036]

[0037] wherein, the actual required energy, which represents the minimum energy required for the actual configuration of the DC side energy storage capacitor of the magnetic resistance type dynamic voltage restorer; the theoretical energy required for compensating the target event, the energy correction coefficient;

[0038] The value of the energy correction coefficient is determined according to the topology of the magnetic resistance type dynamic voltage restorer: for the device using a three-phase four-bridge arm topology, the value range of the energy correction coefficient is [1.5, 1.8], and for the device using a back-to-back converter topology, the value range of the energy correction coefficient is [1.1, 1.3].

[0039] Further, the optimization configuration scheme is generated in particular as follows:

[0040] The maximum compensation voltage and the rated output current are taken as key electrical parameters to determine the selection criteria of the insulated gate bipolar transistor in the power module of the main circuit of the magnetic reactive dynamic voltage restorer, so as to meet the constraint conditions of the collector and the emitter rated voltage and the rated current, the constraint condition of the rated voltage is , and the constraint condition of the rated current is , wherein is the rated voltage of the collector and the emitter, is the safety margin coefficient of the maximum compensation voltage, is the maximum compensation voltage, is the rated current of the collector, is the safety margin coefficient of the rated output current, is the rated output current of the magnetic reactive dynamic voltage restorer;

[0041] The actual required energy is converted into the capacity value of the DC side support capacitor, and the capacity of the DC side energy storage capacitor meets the following requirements:

[0042]

[0043] , wherein is the capacity value of the DC side support capacitor, is the DC side rated working voltage, is the minimum working voltage allowed by the capacitor;

[0044] The DC side rated working voltage meets: so as to determine that the inverter can output the maximum compensation voltage in the linear modulation area;

[0045] The optimization configuration scheme at least includes the maximum compensation voltage, the rated output current, the actual required energy and the compensation strategy.

[0046] The application further provides an optimization configuration device of the magnetic reactive dynamic voltage restorer, which is used for realizing the optimization configuration method of the magnetic reactive dynamic voltage restorer and comprises:

[0047] A data and parameter acquisition module is configured to acquire relevant data of historical voltage sag events of a target distribution bus node in a statistical period, the relevant data including the sag depth, the duration and the phase jump angle of each voltage sag event, and to acquire electrical characteristic parameters of a load motor connected downstream of the bus, including the rated power, the rated voltage, the power factor and the critical stall time.

[0048] An event analysis and strategy decision module is configured to filter out voltage sag events with sag depth exceeding a preset load tolerance threshold and duration less than a critical stall time based on relevant data and electrical characteristic parameters of historical voltage sag events, to form a set of events to be compensated, to calculate a maximum value of absolute values of phase jump angles of all voltage sag events in the set, to determine a relationship between the maximum value and a preset threshold, and to determine a compensation strategy;

[0049] A core electrical parameter calculation module is configured to determine a maximum compensation voltage required to be provided by a magnetic dynamic voltage restorer based on a maximum sag depth in the set of events to be compensated, to determine a rated output current of the magnetic dynamic voltage restorer based on electrical characteristic parameters of a load motor, to calculate a theoretical energy required to compensate for a voltage sag event with the longest duration in the set of events to be compensated based on the compensation strategy, and to determine an energy correction coefficient based on a topology of the magnetic dynamic voltage restorer, to determine an actual required energy of energy storage on a direct current side.

[0050] An optimized configuration scheme generation module is configured to generate an optimized configuration scheme of the magnetic dynamic voltage restorer and output the optimized configuration scheme based on the compensation strategy, the maximum compensation voltage, the rated output current and the actual required energy.

[0051] In the above technical solution, the present application provides technical effects and advantages as follows:

[0052] The present application provides a configuration method that unifies precision and economy for the core problem that impact load motors are abnormally sensitive to voltage sag and prone to stall shutdown. By comprehensively analyzing sag depth, duration and phase jump of historical voltage sag events and closely combining electrical parameters such as critical stall time of load motors, the method can accurately filter out a set of events to be compensated that really cause motor shutdown, and accordingly calculate maximum compensation voltage, rated current and key energy requirement of the device, thereby avoiding capacity waste caused by excessive configuration or protection failure caused by insufficient configuration in traditional methods. More importantly, the method innovatively uses phase jump angle as a basis for selecting a compensation strategy, so that the magnetic dynamic voltage restorer can adaptively optimize its energy throughput while achieving reliable voltage support, significantly reducing capacity configuration requirements and operating costs of energy storage units on the direct current side. BRIEF DESCRIPTION OF DRAWINGS

[0053] Figure 1 The figure is a schematic diagram of the overall method of the present application;

[0054] Figure 2 The figure is a schematic diagram of comparison between sag depth and load tolerance threshold in historical voltage sag events;

[0055] Figure 3A schematic diagram for comparing the duration of historical voltage sag event with critical stall time of the application;

[0056] Figure 4 A schematic diagram for the device structure of the application. DETAILED DESCRIPTION

[0057] In order to make the objects, technical solutions and advantages of the present application clearer, the present application will be further described in detail below with reference to specific embodiments.

[0058] It should be noted that, unless otherwise defined, the technical terms or scientific terms used in the present application should be understood as the common meanings understood by those skilled in the art to which the present application belongs. The terms "first", "second" and similar terms used in the present application do not represent any order, number or importance, but are only used to distinguish different components. The terms "include" or "contain" and similar terms mean that the elements or objects before the terms cover the elements or objects listed after the terms and their equivalents, and do not exclude other elements or objects. The terms "connect" or "connected" and similar terms are not limited to physical or mechanical connections, but can include electrical connections, whether direct or indirect. The terms "upper", "lower", "left", "right" and the like are only used to represent relative positional relationships, and when the absolute positions of the described objects are changed, the relative positional relationships may also be changed accordingly.

[0059] Embodiment:

[0060] Please refer to Figures 1 to 3 The present application provides a technical solution:

[0061] An optimization configuration method of a magnetic resistance type dynamic voltage restorer, the specific steps comprising:

[0062] Step 1: Obtain the relevant data of historical voltage sag events of the target distribution bus node in a statistical period, the relevant data including the sag depth, duration and phase jump angle of each voltage sag event, and obtain the electrical characteristic parameters of the load motor connected downstream of the bus, including rated power, rated voltage, power factor and critical stall time;

[0063] In this embodiment, the target distribution bus node is the most upstream common connection point of the power supply circuit to which the load motor belongs; this node is the key position for evaluating the voltage sag impact of the entire power supply circuit. In the actual power grid structure, multiple loads or sub-circuits may be connected downstream of a distribution bus, and the common connection point is the common power supply source of these loads. In order to accurately identify the target distribution bus node, two ways can be used: power grid topology analysis and power quality monitoring point data correlation. Through power grid topology analysis, specifically: refer to the single-line diagram of the distribution system, starting from the sensitive load motor to be protected, trace upstream to find the first bus node that supplies power to multiple loads or circuits. Through power quality monitoring point data correlation, specifically: if power quality monitoring devices have been deployed in the distribution system, the voltage sag event data of different monitoring points can be analyzed to determine the most upstream monitoring point bus that can represent the overall power quality of the load motor power supply circuit.

[0064] The relevant data of the historical voltage sag event is obtained from a power quality monitoring system, and the statistical period is at least one year. The power quality monitoring system should at least include monitoring terminals installed at the target distribution bus node or its electrical adjacent position, which can continuously record voltage waveform data. The purpose of setting the statistical period to at least one year is to obtain representative voltage sag data samples that can cover various types of sag events that may occur under different seasons, different weather conditions and different system operation modes. A one-year period can generally reflect the typical operation of the system, avoiding statistical result deviation caused by too short data period. In specific implementation, according to actual data availability and requirements for evaluation accuracy, in this embodiment, the statistical period is preferably determined as one year.

[0065] The historical voltage sag event is defined as an event in which the root mean square value of voltage drops to between 0.1pu and 0.9pu of the rated voltage and lasts for 0.5 cycles to 60 cycles; pu represents the unit value, which is a dimensionless unit commonly used in power system analysis, and its value is the ratio of the actual value to the reference value (here, the rated voltage); cycle represents a complete AC sine wave, in a 50Hz system, 1 cycle is equal to 20 milliseconds; in a 60Hz system, 1 cycle is approximately equal to 16.67 milliseconds.

[0066] The determination of each threshold is as follows: the lower limit of the sag depth (0.1 pu): voltage drop below 0.1 pu is usually considered as interruption rather than sag, and most sensitive equipment cannot work normally when the voltage is below 0.1 pu, so this is taken as the dividing point. The upper limit of the sag depth (0.9 pu): according to the relevant standards IEC 61000-4-30, etc., the threshold of voltage sag is usually set at 90% of the rated voltage (i.e. 0.9 pu). Voltage higher than this value has little effect on the operation of most equipment. The lower limit of the duration (0.5 cycles): voltage changes shorter than 0.5 cycles are usually considered as transient or instantaneous phenomena rather than typical voltage sag. The upper limit of the duration (60 cycles): events with a duration of more than 60 cycles (about 1-1.2 seconds) are usually classified as long-time voltage drop or steady-state voltage problem, which is different in nature and handling from short-time voltage sag. In summary, the above-mentioned threshold values are commonly used ranges, and these thresholds can also be adjusted according to the specific load characteristics or relevant special standards concerned.

[0067] The phase jump angle is obtained by intercepting the voltage waveform in a time window before the voltage sag event occurs, where the time window is represented as , the window is selected at the voltage sag starting time one cycle before, is a single cycle. The window length is selected as one cycle (20 ms for 50 Hz system, 16.67 ms for 60 Hz system), in order to obtain the stable voltage phase information of one complete cycle before the sag occurs, and to avoid introducing non-steady-state factors due to too long window. The average value of the fundamental positive sequence voltage phase calculated by the phase-locked loop is taken as the reference phase; the voltage waveform in a time window after the voltage sag event ends and a preset delay is intercepted, where the time window is represented as , the window is selected after the voltage sag event ends and a preset delay is introduced. The purpose of the preset delay is to wait for the system voltage to fully recover to a stable state after the sag ends, avoiding measuring the phase during the voltage recovery transient process. The preset time delay is preferably in the range of 5 to 30 cycles (i.e. 100 ms to 600 ms in a 50 Hz system). The specific value should be determined according to the short-circuit capacity of the system, the load characteristics and the depth of the voltage sag. For a system with low strength or deep voltage sag, a larger value (e.g. 20-30 cycles) can be taken to ensure voltage stability. For the voltage waveform data in the above two time windows, the average value of the fundamental positive sequence voltage phase calculated by a phase-locked loop is taken as the post-sag phase. The phase-locked loop is a closed-loop control system that can quickly and accurately track the phase of a signal, and is particularly suitable for phase extraction under distorted or non-steady-state conditions. In specific implementation, a phase-locked loop based on a second-order generalized integrator or other improved phase-locked loop algorithms capable of quickly locking the phase can be used to improve the accuracy and speed of phase detection under voltage sag conditions. The difference between the reference phase and the post-sag phase is calculated to obtain the phase jump angle, which is usually expressed in degrees or radians. Among them, is the starting time of the voltage sag event.

[0068] The electrical characteristic parameters of the load motor connected downstream of the bus include rated power, rated voltage, power factor and critical stall time. The rated power, rated voltage and power factor are standard motor nameplate parameters or data explicitly given in the equipment technical specification, which can be directly obtained from the documents provided by the equipment manufacturer.

[0069] Step 2: Based on the related data of historical voltage sag events and the electrical characteristic parameters, voltage sag events with a sag depth exceeding a preset load tolerance threshold and a duration less than the critical stall time are selected to form a set of events to be compensated. The maximum value of the absolute value of the phase jump angle of all voltage sag events in the set is calculated to determine the relationship between the maximum value and the preset threshold, thereby determining the compensation strategy.

[0070] In this embodiment, the critical stall time refers to the maximum time that the motor can withstand when it is subjected to voltage sag, from the start of its speed drop to the final stall stop, which is a key parameter for determining whether the motor will stall during voltage sag. The method for obtaining the critical stall time includes consulting the voltage sag tolerance curve provided by the equipment manufacturer (such as ITIC curve or SEMI curve for specific equipment application), experimental testing, and simulation calculation based on the motor dynamic model. If the accurate mechanical equipment rotational inertia cannot be obtained, it can be estimated according to engineering experience: generally, for common centrifugal pumps, fan loads, the total rotational inertia of the system is about 1.1 to 1.5 times the rotational inertia of the motor rotor itself. After sensitivity analysis, the intermediate value of 1.3 times can be used for preliminary calculation. In this embodiment, the preferred method for obtaining the critical stall time is as follows: the critical stall time is determined by the stall protection parameter set in the motor control unit of the load motor, the rated angular velocity, rated power, and total rotational inertia of the load motor are collected, the total rotational inertia is the sum of the rotational inertia of the load motor rotor itself and the equivalent rotational inertia of the mechanical equipment driven by the load motor converted to the motor shaft, and the critical stall time is calculated, and the calculation formula is as follows:

[0071]

[0072] wherein, is the critical stall time, is the total rotational inertia, is the rated angular velocity, is the rated power of the load motor, is the critical stall acceleration, which is 80% of the rated angular velocity. The basis for setting the critical stall acceleration is as follows: for most induction motors and synchronous motors, when the speed drops to 70% to 85% of the rated speed, the torque-slip characteristic curve enters the unstable region, and the motor will be difficult to recover to the rated speed and eventually stall. Selecting 80% as a representative engineering threshold can ensure safety margin while avoiding excessive conservatism. For loads with special torque-speed characteristics (such as constant torque loads), the threshold can be adjusted to 75% or 85% according to the specific stall critical point.

[0073] The above formula for calculating the critical stall time is derived from the dynamic theorem of rotating objects. The kinetic energy released by the motor during voltage sag, from to , needs to be equal to the energy consumed by the load during this period (approximately the rated power multiplied by the critical stall time). The coefficient 1 / 2 in the formula is a part inherent to the dynamic formula. The premise for applying this formula is to assume that during the short voltage sag period, the rated power of the load motor The constant is maintained. This is reasonable for constant power loads or approximately constant power loads. For loads whose torque varies with speed (such as the square torque load of a fan or pump), this result is conservative (i.e., the actual critical stall time can be slightly longer), which provides additional safety margin for the system.

[0074] In this embodiment, determining the set of events to be compensated specifically includes:

[0075] The set of events to be compensated is specifically represented as: , wherein, represents the set of events to be compensated, is the index of the voltage sag event, is the sag depth unit value of the event, is the duration of the event, is the phase jump angle of the event, is a load tolerance threshold preset according to the characteristics of the impact load, and its physical meaning is that when the voltage sag depth is lower than this threshold, the load motor cannot maintain stable operation and there is a risk of stall. Its specific value should be based on the low voltage tolerance capability of the load motor. The critical stable operation voltage of a general induction motor is usually near 80% to 85% of the rated voltage. Therefore, A typical value of one is 0.8pu (unit value). For more sensitive devices or higher requirements, it can be increased to 0.85pu; for stronger clicks, it can be relaxed to 0.75pu. Of course, the most accurate determination method is to refer to the voltage sag tolerance curve of the specific load motor (if the manufacturer provides it), and the lower limit of the voltage that causes the motor to lose stability as . represents the critical stall time of the load motor.

[0076] The logic of screening out the set of events to be compensated is to screen out all events whose severity is deep enough (i.e. , meaning that the voltage drop is greater than the drop amplitude threshold that the load can withstand), but the duration is not long enough to make the motor stall ( ). For events, even if the dynamic voltage restorer (DVR) fully compensates, the motor may have stalled, and compensation is meaningless, so it is not considered. This set is the set of events to be compensated that need DVR action to prevent motor stall.

[0077] In this embodiment, the sag depth unit value and the duration of 30 events are obtained, and the load tolerance threshold is set to 0.2pu and the critical stall time is set to 500ms. The specific data is shown in the following table:

[0078] Table 1: Schematic table of relevant data for determining whether a historical voltage sag event is a to-be-compensated event

[0079]

[0080] According to the above table, and Figure 2 and Figure 3 It can be clearly distinguished which historical voltage sag events are to-be-compensated events and which historical voltage sag events are not to-be-compensated events.

[0081] The absolute values of the phase jump angles of all voltage sag events in the to-be-compensated event set are calculated, and the maximum value among them is screened out. If the maximum value is not greater than the preset phase jump judgment threshold, it is determined that there is no effective phase jump to be compensated. If the maximum value is greater than the preset phase jump judgment threshold, it is determined that there is an effective phase jump to be compensated. The preset phase jump judgment threshold is used to distinguish the effective phase jump. The setting of this threshold needs to balance two factors: a too small threshold will cause the strategy to switch to the higher energy consumption same-phase compensation mode too frequently; a too large threshold will ignore the phase jump that is not large but enough to cause transient torque shock of the motor. Based on engineering practice and motor transient theory, when the phase jump is more than 10° to 20°, significant transient torque shock (may be more than 2 times the rated torque) will be generated in the induction motor, thereby causing mechanical stress to the transmission shaft system and possibly triggering the protection device to malfunction. Therefore, a recommended value range of the phase jump judgment threshold is 10° to 20°, and the preferred value is 15°. This value can effectively capture the phase jump that has potential harm.

[0082] In this embodiment, determining the compensation strategy specifically includes:

[0083] If it is determined that there is no effective phase jump of compensation, the in-phase voltage compensation strategy is selected; the in-phase voltage compensation strategy refers to controlling the compensation voltage output by the magnetic dynamic voltage restorer to be in the same phase as the grid residual voltage. When implementing this strategy, the controller of the magnetic dynamic voltage restorer performs the following operations: acquiring the waveform of the grid residual voltage in real time, and extracting the phase angle thereof through a phase-locked loop; the phase-locked loop needs to have the ability to quickly and accurately lock the phase under the conditions of voltage distortion and sag. Taking the phase angle as a reference, the phase angle of the output voltage vector of the inverter unit of the magnetic dynamic voltage restorer is controlled to be synchronized with the phase angle, so as to meet the control target that the phase angle of the output voltage vector is in the same phase as the phase angle of the grid residual voltage waveform. Implementing this strategy makes the compensation voltage injected by the magnetic dynamic voltage restorer used to lift the amplitude of the grid residual voltage, and the active power ratio in the output power of the magnetic dynamic voltage restorer is not less than 90%. Since the compensation voltage is in the same phase as the residual voltage, the two vectors are added, and the voltage amplitude that needs to be provided by the DVR is minimum, but the output current of the DVR is basically the same as the load current. Therefore, in the apparent power output by the DVR, most of the power is active power, which is used to directly supplement the energy lacking in the grid. The active power ratio in the output power is not less than 90%, which is a quantitative description of the energy characteristics under this strategy, and the root is that the compensation voltage and the load current are close in direction.

[0084] When the compensation is in the same phase, the compensation voltage vector that needs to be injected by the DVR is consistent with the direction of the residual voltage vector. This is the one with the minimum voltage amplitude that needs to be output in all compensation strategies. This reduces the requirement for the modulation ratio of the DVR inverter, reduces the voltage stress of the switching device, and improves the system reliability and overload capacity. The control target is to be in the same phase as the grid residual voltage, and the phase of the grid voltage can be quickly and stably acquired through the phase-locked loop. In contrast, the minimum energy compensation needs to accurately detect the phase of the load current, and the load current may be distorted and mutated at the moment of voltage sag, increasing the complexity and uncertainty of control. At the same time, the in-phase compensation also maintains the continuity of the load voltage, and the load current will not produce sharp phase changes due to the compensation strategy. The minimum energy compensation will instantaneously change the voltage phase at the load end, which may cause transient impact of the load current.

[0085] The active power ratio threshold is explicitly set to 90%, which sets a quantitative and assessable technical index for the effective implementation of the strategy. It ensures that the system is indeed running in the expected low-energy and high-efficiency state when executing this strategy. If the active power ratio is significantly lower than this value, for example 80%, it means that unnecessary orthogonal components are introduced in the compensation voltage vector, which violates the original intention of in-phase compensation and will cause additional reactive current in the DVR itself, increasing the stress on the switching devices and magnetic elements, which is a manifestation of the unanticipated effect of the control strategy. The selection of the specific value of 90% is based on the comprehensive consideration of the control system accuracy, sensor measurement error, and non-ideal factors under actual grid conditions. In an ideal situation, perfect in-phase compensation should have an active power ratio of 100%. However, in actual engineering, there is a slight delay or error in the phase tracking of the phase-locked loop, and the dead time of the power switching device also introduces waveform distortion, resulting in a small amount of reactive power in the output power. By setting the threshold to 90% instead of a higher value of 95% or 98%, a reasonable fault tolerance space is provided for these unavoidable non-ideal factors. This tolerance range ensures that the technical feature is practical in industrial applications, rather than a theoretical limit.

[0086] If it is determined that there is an effective phase jump in compensation, the minimum energy compensation strategy is selected; the minimum energy compensation strategy refers to controlling the phase of the compensation voltage output by the magnetic dynamic voltage restorer to be orthogonal to the phase of the load current. When executing this strategy, the controller of the magnetic dynamic voltage restorer performs the following operations: real-time acquisition of the load current waveform, and calculation of its phase angle through a phase-locked loop; based on the phase angle, the phase angle of the output voltage vector of the inverter unit of the magnetic dynamic voltage restorer is controlled to meet the control target of a phase difference of 90 degrees between the phase angle of the load current waveform and the phase angle of the voltage vector; by executing this strategy, energy throughput minimization during the compensation process is achieved. According to the instantaneous power theory, when the voltage and current are orthogonal, the instantaneous active power is zero. This means that in an ideal situation, there is no active power exchange between the DVR and the load, the DVR does not provide or absorb active energy, and only provides reactive power to maintain the load voltage. Thus, energy throughput minimization during the compensation process is achieved. The energy required by the DVR only comes from the small voltage fluctuations of its DC side capacitor and the losses of the switching devices, without the need to obtain a large amount of active power from the grid or energy storage units, greatly reducing the capacity demand of the DVR's own energy storage unit (such as the capacitor), improving the economy and reliability of the equipment.

[0087] This strategy is particularly suitable for compensating for voltage sags accompanied by large phase jumps, because in-phase compensation would require the DVR to provide enormous active power to correct the phase. When a voltage sag occurs, we must choose between the ideal compensation effect and the practical feasibility of the compensation device. In-phase voltage compensation provides the most ideal power quality, correcting both voltage amplitude and phase simultaneously, leaving the load completely unaware of any disturbance. However, this perfection comes at the cost of extremely high energy demands. When the grid voltage experiences an amplitude drop accompanied by a phase jump, the dynamic voltage restorer needs to inject a huge voltage vector to fully restore the load voltage to its pre-sag state. This vector not only needs to fill the amplitude gap but also reverse the entire voltage phase. This reversal process means the DVR must provide a large amount of active power to counteract the power imbalance caused by the grid-side phase jump. This active power must come from the DVR's own energy storage unit. In the worst-case scenario of deep sags and large phase jumps, the energy storage capacity requirements become enormous, leading to a sharp increase in equipment cost, size, and complexity, making it often difficult to implement in practice. In contrast, the minimum energy compensation strategy opts for a more sensible and pragmatic compromise.

[0088] Step 3: Based on the maximum sag depth in the set of events to be compensated, determine the maximum compensation voltage required by the magnetic reactive dynamic voltage restorer. Based on the electrical characteristic parameters of the load motor, determine the rated output current of the magnetic reactive dynamic voltage restorer. Based on the compensation strategy, calculate the theoretical energy required to compensate the voltage sag event with the longest duration in the set of events to be compensated. Based on the topology of the magnetic reactive dynamic voltage restorer, determine the energy correction coefficient to determine the actual energy required for DC side energy storage.

[0089] In this embodiment, the depth of voltage sag events in the set of events to be compensated is compared to determine the maximum depth of voltage sag. Based on the maximum depth of voltage sag and the rated voltage, the maximum compensation voltage is calculated; the maximum compensation voltage is the product of the maximum depth of voltage sag and the rated voltage. This method is based on the design principle of the most severe operating conditions. The device must have the ability to compensate for the maximum possible depth of voltage sag to ensure that the load voltage can be restored to a safe level in all events to be compensated. In practical engineering, to further improve reliability, a certain safety margin, typically 10% to 15%, can be considered based on the calculated maximum compensation voltage. For example, if the calculated maximum compensation voltage is 0.4 times the rated voltage, the maximum compensation voltage capability of the finally selected device can be set to 0.45 times the rated voltage.

[0090] The rated output current of the magnetic reactive dynamic voltage restorer is preset to be no less than the maximum operating current of the load motor, and is determined by the following formula:

[0091]

[0092] in, This is the rated output current of the magnetic reactive dynamic voltage restorer. The rated power of the load motor. The rated voltage of the load motor. The rated power factor of the load motor. The rated impedance angle of the load motor;

[0093] This formula calculates the effective value of the line current when the load operates at rated power, rated voltage, and rated power factor. Requirements: This value is not less than a certain value to ensure that the device can continuously bear the full current of the load during the compensation period without shutting down due to its own overcurrent. For motor loads, especially direct-start or heavy-load start motors, the starting current can be 5 to 7 times the rated current. However, magnetic reactive dynamic voltage restorers are usually designed to withstand only the steady-state operating current, and the motor starting process can be handled by a bypass circuit. Therefore, the maximum operating current in this context is explicitly defined as the rated operating current of the motor, not its starting current or short-time overload current. If the load has known periodic short-time overloads, then... The capacity needs to be increased accordingly to cover this overload condition.

[0094] Theoretical energy is the core factor in determining the size of the DC-side energy storage capacitor. The theoretical energy required for calculation based on the compensation strategy specifically includes:

[0095] If the selected compensation strategy is an in-phase voltage compensation strategy, and the voltage sag event with the longest duration in the set of events to be compensated is taken as the target event, then the theoretical energy required to compensate the target event is calculated as follows:

[0096]

[0097] in, When selecting an in-phase voltage compensation strategy, the theoretical energy required to compensate for the target event is... The compensation voltage for the target event. The load motor current is denoted as ; where , , This represents the per-unit value of the descent depth of the target event. Indicates the duration of the target event; under the in-phase voltage compensation strategy, the compensation voltage output by the device. With load current Since they are in phase, the power output of the device is... All of this is active power. This power multiplied by the duration... This refers to the total energy that needs to be extracted from the DC-side energy storage of the device.

[0098] In the above formula, It is directly determined by the product of three independent variables. Its technical essence reflects the core principle of the in-phase voltage compensation strategy: the device needs to fully compensate for the active power missing from the power grid. Compensation voltage Proportional to the depth of the sag, it represents the voltage gap that needs to be compensated; load current This represents the energy flow that needs to be maintained; while the duration... This represents the length of time that compensation needs to be maintained. Therefore, the product of these three factors... This intuitively quantifies the total available energy that the unit must release from its own energy storage in order to maintain rated load operation throughout the entire sag. This dependent variable... This directly reflects the basic requirements of the device for DC-side energy storage capacity in the most direct compensation mode, and its technical effect is to provide a clear theoretical energy benchmark for subsequent hardware configuration. If the sag is deeper ( Increased size, heavier load ( Increase) or longer event ( An increase in energy demand will linearly lead to an increase in energy requirements. The increase in energy storage capacity forces designers to make corresponding investments in energy storage capacity.

[0099] If the selected compensation strategy is the minimum energy compensation strategy, the theoretical energy required to compensate the target event is calculated as follows:

[0100]

[0101] in, To select the minimum energy compensation strategy, the theoretical energy required to compensate the target event is... This indicates the phase transition angle of the target event. Indicates the duration of the target event.

[0102] This is a key refinement of the invention. Under the minimum energy strategy, the device output voltage and load current are orthogonal in phase, ideally without exchanging active power. However, when a phase jump occurs in the system, the rated impedance angle of the load... It may change, or for accurate compensation, the phase of the compensation voltage may need to be fine-tuned, which will introduce a small active component. This term is precisely for quantifying the small amount of active power generated under this non-ideal condition. Its value is much less than 1, therefore... Typically much smaller This confirms the advantages of the minimum energy strategy in energy saving.

[0103] The above formula introduces the key independent variables, the phase transition angle and the rated impedance angle of the load, and uses their functions... To correct the energy calculation. The dependent variable in this formula. This reflects the limited but essential active power that must be provided by the device due to non-ideal conditions (mainly phase jumps) that cannot be completely avoided under the strategy of minimizing energy throughput. The technical principle is that ideal minimum energy compensation requires the output voltage and load current to be strictly orthogonal, thus achieving zero net active power. However, when a phase jump occurs, the system's voltage phase reference changes abruptly. To achieve correct voltage compensation under the new phase reference after the jump, or due to the rated impedance angle of the load... As a result, the compensation voltage can no longer maintain a perfect 90-degree relationship with the load current, thus generating a small active power component, namely... Item. The dependent variable This precise capture and quantification of the subtle yet crucial energy requirement achieves accurate modeling of the actual energy consumption of a minimum energy strategy, rather than remaining on ideal assumptions. When the phase transitions... With respect to the rated impedance angle of the load The closer the difference is to 90 degrees, The closer to zero, The smaller the value, the closer it is to the ideal zero-energy state; conversely, if the difference is close to 0 or 180 degrees, energy consumption will increase significantly.

[0104] The longest-lasting voltage sag event is selected from the set of events to be compensated as the target event, and the theoretical energy required for the target event is obtained. Given a fixed compensation voltage and load current, the required energy is proportional to the duration. Selecting the longest-lasting event for calculation is based on the principle of the most stringent energy demand conditions, ensuring that the device's energy storage capacity is sufficient to support the compensation tasks for all events to be compensated.

[0105] In this embodiment, determining the actual energy required for DC-side energy storage specifically includes:

[0106] The energy correction factor is determined based on the device topology to calculate the actual energy required for DC-side energy storage, as shown in the following formula:

[0107]

[0108] in, The energy required in practice represents the minimum energy required for the DC-side energy storage capacitor of the magnetic reactive dynamic voltage restorer. This represents the theoretical energy required to compensate for the target event. This is the energy correction factor;

[0109] The energy correction coefficient is determined based on the topology of the reactive dynamic voltage restorer: for devices using a three-phase four-arm topology, the energy correction coefficient ranges from [1.5, 1.8]. The three-phase four-arm topology, by adding an arm on the DC side to handle zero-sequence voltage and current, is more complex to control, resulting in relatively high switching and core losses. Furthermore, this topology is relatively inefficient in energy feedback and cycling processes, thus requiring a larger energy storage capacity to cover these losses, hence the larger correction coefficient. For devices using a back-to-back converter topology, the energy correction coefficient ranges from [1.1, 1.3]. The back-to-back topology consists of two converters connected via a DC bus, one of which is connected to the grid. This structure allows for bidirectional flow of active power between the grid and the load, and more efficient management of the DC-side capacitor's energy. Especially during compensation, it can absorb some active power from the grid side to supplement the DC-side capacitor, rather than relying solely on the initial energy storage of the capacitor; therefore, the absolute demand for capacitor energy storage is smaller, and the correction coefficient is also smaller. In specific engineering designs, a specific value should be selected from the given range. For applications requiring high reliability, the upper limit of the range should be used (e.g., 1.8 for four-axle arms and 1.3 for back-to-back bridges); for cost-sensitive applications with relatively mild operating conditions, the lower limit of the range can be used.

[0110] Dependent variable This represents the actual energy value that the DC-side energy storage element (usually a capacitor) of the reactive dynamic voltage restorer ultimately needs to be configured with. Its independent variable is the theoretical energy calculated above. and an energy correction factor greater than 1 . The reason for and The proportionality is because theoretical energy is the minimum value required to complete compensation in an ideal, lossless system. The dependent variable... This reflects the engineering-feasible energy storage capacity that must be configured in a real physical device, taking into account all energy losses and topology limitations. (Correction factor) The introduction of this independent variable effectively bridges theoretical calculations with engineering practice. It systematically encompasses factors such as the switching losses of the converter within the device, the iron and copper losses of the magnetic components, the power consumption of the control system, and the energy cycle efficiency resulting from a specific topology. As the device topology varies, The value changes, precisely reflecting the inherent differences in energy utilization efficiency among different hardware solutions. For example, a more efficient back-to-back topology corresponds to a smaller... The value corresponds to a larger value, while the four-arm topology, which has relatively higher losses, corresponds to a larger value. Value. Therefore, As a final and reliable design output, it ensures that the configured device has the energy reserves to complete all compensation tasks in the real world, avoiding compensation failure due to insufficient energy storage.

[0111] Step 4: Based on the compensation strategy, maximum compensation voltage, rated output current, and actual required energy, generate and output an optimized configuration scheme for the magnetic reactive dynamic voltage restorer.

[0112] In this embodiment, generating the optimized configuration scheme specifically includes:

[0113] The maximum compensation voltage and rated output current are used as key electrical parameters to determine the selection criteria for the insulated-gate bipolar transistor (IGBT) in the main circuit power module of the magnetic reactive dynamic voltage restorer. This ensures that the rated collector and emitter voltages and currents are met. The rated voltage constraint is as follows: ; The calculation is the theoretical maximum AC voltage applied across a single power switching device (IGBT) when the device outputs the maximum compensated voltage peak value. This refers to the rated collector-emitter voltage of the IGBT, i.e., the highest voltage it can safely interrupt. The constraints on the rated current are: ,in, This is the rated voltage of the collector and emitter. The safety margin factor for the maximum compensation voltage. For the maximum compensation voltage, This is the rated current of the collector (usually referring to the DC current value). Since the IGBT needs to carry a sinusoidal output current, its peak current is... ; The safety margin factor is the rated output current. This is the rated output current of the magnetic reactive dynamic voltage restorer. The introduction of this feature is to address non-steady-state factors such as operational overvoltages, surge impacts, and voltage spikes during switching processes in the power grid, ensuring that the IGBT operates within the linear safe region. The value typically ranges from 1.5 to 2. This range is determined based on common design specifications and reliability requirements in the industry. For applications with harsh power grid environments (such as near large load switching points) and extremely high reliability requirements, a higher value (such as 1.8 to 2.0) should be used; for applications with relatively stable environments and strict cost control, the lower limit (such as 1.5) can be used. A value of 1.5 means a 50% voltage margin, while 2.0 means a 100% margin. The introduction of this technology is intended to cover peak current, switching ripple, and provide some short-term overload capability. The specific value range is typically from 1.8 to 2.5. This range takes into account the crest factor of the sine wave and necessary engineering margins. A typical and safe value is 2.0, which means that the rated DC current of the IGBT is twice the effective value of the device's rated output current, sufficient to cover its peak current (approximately 1.414 times) and leave ample margin to cope with current distortion and dynamic overshoot. For loads that need to withstand periodic inrush currents, a larger value should be used.

[0114] The actual required energy is converted into the capacitance value of the DC-side supporting capacitor, and the capacitance of the DC-side energy storage capacitor meets the following requirements:

[0115]

[0116] in, This refers to the capacitance value of the DC-side supporting capacitor. This is the rated operating voltage on the DC side. This is the minimum permissible operating voltage for the capacitor. The total energy required for compensation is equal to the energy dissipated from the capacitor's rated voltage. Discharge to the minimum permissible voltage The energy difference released. The formula, through transformation, directly solves for the minimum capacitance value that satisfies this energy release requirement.

[0117] The rated operating voltage on the DC side meets the following requirements: This is to determine whether the inverter can output the maximum compensation voltage within the linear modulation region. In a voltage source inverter, in order to output a sinusoidal voltage without distortion within the linear modulation region via pulse width modulation, its DC-side voltage must be greater than the peak value of that sinusoidal voltage. It requires the maximum effective value of the output compensation voltage, with a peak value of . Therefore, setting the DC-side rated operating voltage to meet the above conditions is a fundamental prerequisite for ensuring that the inverter can output the required maximum voltage without entering the overmodulation region.

[0118] The minimum allowable operating voltage of the capacitor is the lowest DC voltage threshold that the inverter can use to maintain normal pulse width modulation and output current control. Its value is typically set to [value to be filled in]. 60% to 70%. For example, if If it is 800V, then The value can be set from 500V to 600V. This threshold ensures that even when the DC voltage is at its lowest at the end of the compensation period, the inverter can still effectively control the output voltage, avoiding modulation failure or severe distortion of the output waveform due to excessively low DC voltage. The specific setting of this value should refer to the technical specifications of the selected inverter control chip or control algorithm.

[0119] The optimized configuration scheme includes at least: maximum compensation voltage, rated output current, actual energy required, and compensation strategy. This scheme transforms abstract voltage sag event data and load characteristics into specific, quantifiable design inputs for power electronic devices.

[0120] Please see Figure 4 The present invention also provides an optimized configuration device for a magnetic reactive dynamic voltage restorer, which is used to implement the above-mentioned optimized configuration method for a magnetic reactive dynamic voltage restorer, comprising:

[0121] The data and parameter acquisition module is used to acquire relevant data of historical voltage sag events of the target distribution bus node within the statistical period. The relevant data includes the sag depth, duration and phase jump angle of each voltage sag event. At the same time, it acquires the electrical characteristic parameters of the load motor connected downstream of the bus, including rated power, rated voltage, power factor and critical stall time.

[0122] The event analysis and strategy decision-making module is used to filter out voltage sag events whose sag depth exceeds the preset load tolerance threshold and whose duration is less than the critical stall time based on relevant data and electrical characteristic parameters of historical voltage sag events, forming a set of events to be compensated. The module calculates the maximum value of the absolute value of the phase jump angle of all voltage sag events in the set to determine the relationship between the maximum value and the preset threshold, thereby determining the compensation strategy.

[0123] The core electrical parameter calculation module is used to determine the maximum compensation voltage required by the magnetic reactive dynamic voltage restorer based on the maximum sag depth in the set of events to be compensated, determine the rated output current of the magnetic reactive dynamic voltage restorer based on the electrical characteristic parameters of the load motor, calculate the theoretical energy required to compensate the voltage sag event with the longest duration in the set of events to be compensated based on the compensation strategy, and determine the energy correction coefficient based on the topology of the magnetic reactive dynamic voltage restorer in order to determine the actual energy required for DC side energy storage.

[0124] The optimized configuration scheme generation module is used to generate and output an optimized configuration scheme for the magnetic reactive dynamic voltage restorer based on the compensation strategy, maximum compensation voltage, rated output current and actual required energy.

[0125] The above formulas are all dimensionless calculations. The formulas are derived from software simulations based on a large amount of collected data to obtain the most recent real-world results. The preset parameters in the formulas are set by those skilled in the art according to the actual situation.

[0126] The above embodiments can be implemented, in whole or in part, by software, hardware, firmware, or any other combination thereof. When implemented in software, the above embodiments can be implemented, in whole or in part, as a computer program product. Those skilled in the art will recognize that the units and algorithm steps of the various examples described in conjunction with the embodiments disclosed herein can be implemented by electronic hardware, or a combination of computer software and electronic hardware. Whether these functions are implemented in hardware or software depends on the specific application and design constraints of the technical solution.

[0127] The units described as separate components may or may not be physically separate. The components shown as units may or may not be physical units; they may be located in one place or distributed across multiple network units. Some or all of the units can be selected to achieve the purpose of this embodiment, depending on actual needs.

[0128] The above description is merely a specific embodiment of this application, but the scope of protection of this application is not limited thereto. Any changes or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in this application should be included within the scope of protection of this application.

Claims

1. An optimized configuration method for a magnetic reactive dynamic voltage restorer, characterized in that, The specific steps include: Step 1: Obtain relevant data of historical voltage sag events of the target distribution bus node within the statistical period. The relevant data includes the sag depth, duration and phase jump angle of each voltage sag event. At the same time, obtain the electrical characteristic parameters of the load motor connected downstream of the bus, including rated power, rated voltage, power factor and critical stall time. Step 2: Based on the relevant data and electrical characteristic parameters of historical voltage sag events, select voltage sag events whose sag depth exceeds the preset load tolerance threshold and whose duration is less than the critical stall time to form a set of events to be compensated. Calculate the maximum value of the absolute value of the phase transition angle of all voltage sag events in the set to determine the relationship between the maximum value and the preset threshold, thereby determining the compensation strategy. Step 3: Based on the maximum sag depth in the set of events to be compensated, determine the maximum compensation voltage required by the magnetic reactive dynamic voltage restorer. Based on the electrical characteristic parameters of the load motor, determine the rated output current of the magnetic reactive dynamic voltage restorer. Based on the compensation strategy, calculate the theoretical energy required to compensate the voltage sag event with the longest duration in the set of events to be compensated. Based on the topology of the magnetic reactive dynamic voltage restorer, determine the energy correction coefficient to determine the actual energy required for DC side energy storage. Step 4: Based on the compensation strategy, maximum compensation voltage, rated output current, and actual energy requirements, generate and output an optimized configuration scheme for the magnetic reactive dynamic voltage restorer; Calculate the absolute value of the phase jump angle of all voltage sag events in the set of test specimens to be compensated, and filter out the maximum value. If the maximum value is not greater than the preset phase jump judgment threshold, it is determined that there is no effective phase jump for compensation. If the maximum value is greater than the preset phase jump judgment threshold, it is determined that there is an effective phase jump for compensation. If it is determined that there is no effective phase jump for compensation, then the in-phase voltage compensation strategy is selected; the in-phase voltage compensation strategy means that the compensation voltage output by the magnetic reactive dynamic voltage restorer is in the same phase as the residual voltage of the grid; if it is determined that there is an effective phase jump for compensation, then the minimum energy compensation strategy is selected; the minimum energy compensation strategy means that the compensation voltage output by the magnetic reactive dynamic voltage restorer is orthogonal to the phase of the load current. The depth of voltage sag events in the set of events to be compensated is compared to determine the maximum depth of voltage sag. The maximum compensation voltage is calculated based on the maximum depth of voltage sag and the rated voltage. The maximum compensation voltage is the product of the maximum depth of voltage sag and the rated voltage. The rated output current of the preset magnetic reactive dynamic voltage restorer, i.e., not less than the maximum operating current of the load motor, is determined by the following formula: in, This is the rated output current of the magnetic reactive dynamic voltage restorer. The rated power of the load motor. The rated voltage of the load motor. The rated power factor of the load motor. The rated impedance angle of the load motor; The theoretical energy required for calculation based on the compensation strategy specifically includes: If the selected compensation strategy is an in-phase voltage compensation strategy, and the voltage sag event with the longest duration in the set of events to be compensated is taken as the target event, then the theoretical energy required to compensate the target event is calculated as follows: in, When selecting an in-phase voltage compensation strategy, the theoretical energy required to compensate for the target event is... The compensation voltage for the target event. The load motor current is denoted as ; where , , This represents the per-unit value of the descent depth of the target event. Indicates the duration of the target event; If the selected compensation strategy is the minimum energy compensation strategy, the theoretical energy required to compensate the target event is calculated as follows: in, The theoretical energy required to compensate the target event when selecting the minimum energy compensation strategy. This indicates the phase transition angle of the target event.

2. The optimized configuration method for a magnetic reactive dynamic voltage restorer according to claim 1, characterized in that, The target power distribution bus node is the upstream common connection point of the power supply circuit to which the load motor belongs; The relevant data of the historical voltage sag events are obtained from the power quality monitoring system, and the statistical period is at least one year. The historical voltage sag event is defined as an event in which the root mean square voltage value drops to between 0.1 pu and 0.9 pu of the rated voltage and the duration is between 0.5 cycles and 60 cycles. pu represents the per-unit value and cycle represents a complete AC sine wave. The phase jump angle is obtained by capturing the voltage waveform within a time window preceding the voltage sag event. This time window is denoted as... The average value of the fundamental positive-sequence voltage phase is calculated using a phase-locked loop as the reference phase; the voltage waveform is captured for a time window after the voltage sag event ends, and this time window is represented as... The average value of the fundamental positive sequence voltage phase is calculated using a phase-locked loop as the phase after the sag. The difference between the reference phase and the phase after the temporary drop is calculated to obtain the phase jump angle; wherein, This represents the start time of the voltage sag event. For a single power frequency cycle, This is the preset delay.

3. The optimized configuration method for a magnetic reactive dynamic voltage restorer according to claim 2, characterized in that, Obtaining the critical stall time specifically includes: determining the critical stall time through stall protection parameters set in the motor control unit of the load motor; collecting the rated angular velocity, rated power, and total moment of inertia of the load motor; the total moment of inertia being the sum of the moment of inertia of the load motor rotor itself and the equivalent moment of inertia of the mechanical equipment it drives, referred to the motor shaft; and calculating the critical stall time using the following formula: in, This is the critical stall time. The total moment of inertia, The rated angular velocity, This is the critical stall acceleration, which is 80% of the rated angular velocity. This is the rated power of the load motor.

4. The optimized configuration method of a magnetic reactive dynamic voltage restorer according to claim 1, characterized in that, Determining the set of events to be compensated specifically includes: The filtering of the set of events to be compensated is specifically represented as follows: ,in, Represents the set of events to be compensated. This is an index for voltage sag events. This is the per-unit value of the temporary descent depth for this event. The duration of the event, The phase transition angle of the event. The load tolerance threshold is preset based on the characteristics of impact load. This indicates the critical stall time of the load motor.

5. The optimized configuration method of a magnetic reactive dynamic voltage restorer according to claim 4, characterized in that, Determining the compensation strategy specifically includes: When implementing the in-phase voltage compensation strategy, the controller of the magnetic reactive dynamic voltage restorer performs the following operations: It acquires the waveform of the residual grid voltage in real time and extracts its phase angle through a phase-locked loop; using this phase angle as a reference, it controls the phase angle of the output voltage vector of the magnetic reactive dynamic voltage restorer inverter unit to synchronize with it, so as to meet the control objective that the phase angle of the residual grid voltage waveform and the phase angle of the output voltage vector are in phase; implementing this strategy ensures that the compensation voltage injected by the magnetic reactive dynamic voltage restorer is used to increase the amplitude of the residual grid voltage, and that the active power in its output power accounts for no less than 90%. When executing the minimum energy compensation strategy, the controller of the magnetic reactive dynamic voltage restorer performs the following operations: acquires the load current waveform in real time and calculates its phase angle through a phase-locked loop; based on the phase angle, controls the phase angle of the output voltage vector of the inverter unit of the magnetic reactive dynamic voltage restorer to meet the control objective that the phase difference between the phase angle of the load current waveform and the phase angle of the voltage vector is 90 degrees; and executes this strategy to minimize the energy throughput during the compensation process.

6. The optimized configuration method of a magnetic reactive dynamic voltage restorer according to claim 1, characterized in that, Determining the actual energy required for DC-side energy storage specifically includes: The energy correction factor is determined based on the device topology to calculate the actual energy required for DC-side energy storage, as shown in the following formula: in, The energy required in practice represents the minimum energy required for the DC-side energy storage capacitor of the magnetic reactive dynamic voltage restorer. This represents the theoretical energy required to compensate for the target event. This is the energy correction factor; The value of the energy correction coefficient is determined according to the topology of the magnetic reactive dynamic voltage restorer: for devices using a three-phase four-arm topology, the value of the energy correction coefficient is in the range of [1.5, 1.8], and for devices using a back-to-back converter topology, the value of the energy correction coefficient is in the range of [1.1, 1.3].

7. The optimized configuration method of a magnetic reactive dynamic voltage restorer according to claim 1, characterized in that, Generating the optimized configuration scheme specifically includes: The maximum compensation voltage and rated output current are used as key electrical parameters to determine the selection criteria for the insulated-gate bipolar transistor (IGBT) in the main circuit power module of the magnetic reactive dynamic voltage restorer. This ensures that the rated collector and emitter voltages and currents are met. The rated voltage constraint is as follows: The constraints for the rated current are: ,in, This is the rated voltage of the collector and emitter. The safety margin factor for the maximum compensation voltage. For the maximum compensation voltage, This is the rated current of the collector. The safety margin factor is the rated output current. This is the rated output current of the magnetic reactive dynamic voltage restorer; The actual required energy is converted into the capacitance value of the DC-side supporting capacitor, and the capacitance of the DC-side energy storage capacitor meets the following requirements: in, This refers to the capacitance value of the DC-side supporting capacitor. This is the rated operating voltage on the DC side. This is the minimum operating voltage allowed for the capacitor; The rated operating voltage on the DC side meets the following requirements: This is to determine whether the inverter can output the maximum compensation voltage within the linear modulation region; The optimized configuration scheme includes at least: maximum compensation voltage, rated output current, actual required energy, and compensation strategy.

8. An optimized configuration device for a magnetic reactive dynamic voltage restorer, characterized in that, The optimized configuration device for a magnetic reactive dynamic voltage restorer is used to implement the optimized configuration method for a magnetic reactive dynamic voltage restorer as described in any one of claims 1-7, including: The data and parameter acquisition module is used to acquire relevant data of historical voltage sag events of the target distribution bus node within the statistical period. The relevant data includes the sag depth, duration and phase jump angle of each voltage sag event. At the same time, it acquires the electrical characteristic parameters of the load motor connected downstream of the bus, including rated power, rated voltage, power factor and critical stall time. The event analysis and strategy decision-making module is used to filter out voltage sag events whose sag depth exceeds the preset load tolerance threshold and whose duration is less than the critical stall time based on relevant data and electrical characteristic parameters of historical voltage sag events, forming a set of events to be compensated. The module calculates the maximum value of the absolute value of the phase jump angle of all voltage sag events in the set to determine the relationship between the maximum value and the preset threshold, thereby determining the compensation strategy. The core electrical parameter calculation module is used to determine the maximum compensation voltage required by the magnetic reactive dynamic voltage restorer based on the maximum sag depth in the set of events to be compensated, determine the rated output current of the magnetic reactive dynamic voltage restorer based on the electrical characteristic parameters of the load motor, calculate the theoretical energy required to compensate the voltage sag event with the longest duration in the set of events to be compensated based on the compensation strategy, and determine the energy correction coefficient based on the topology of the magnetic reactive dynamic voltage restorer in order to determine the actual energy required for DC side energy storage. The optimized configuration scheme generation module is used to generate and output an optimized configuration scheme for the magnetic reactive dynamic voltage restorer based on the compensation strategy, maximum compensation voltage, rated output current, and actual required energy.

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