New energy unit continuous high-low voltage fault ride-through response control method, system and device and storage medium

Abstract

The invention discloses a new energy unit continuous high-low voltage fault ride-through response control method, system and device and a storage medium, and relates to the technical field of new energy power generation grid-connected control, and the method comprises the steps: constructing a fault state recognition mechanism based on a terminal voltage characteristic, judging the operation voltage state of a unit, and generating a ride-through state identifier of each state; executing a dynamic reactive power support control logic based on the ride-through state identifier, dynamically loading a reactive power support instruction according to the voltage level, and outputting support output of the current voltage state; based on a reactive support instruction and support output, driving a ride-through state machine to execute multi-stage switching control, and uniformly controlling high and low voltage continuous ride-through through distribution logic of an energy channel; according to the method, the multi-level crossing control chain is constructed, so that continuous crossing and dynamic support of the new energy unit under high and low voltage disturbance are realized, and the voltage response stability and the system energy coordination are improved.

Description

Technical Field

[0001] This invention relates to the field of grid-connected control technology for new energy power generation, specifically to a method, system, equipment, and storage medium for continuous high and low voltage fault ride-through response control of new energy units. Background Technology

[0002] The proportion of new energy power generation in the power system continues to increase. Wind turbine generators and photovoltaic inverters have become the main grid-connected power sources. They are connected to the grid through power electronic interfaces and have the characteristics of rapid adjustment and flexible control. However, this also makes the system more sensitive to voltage disturbances. When the grid experiences short-term short circuits, tripping, or large load fluctuations, the terminal voltage may drop significantly or rise transiently. If the device cannot maintain stable operation, it is easy to cause grid disconnection and amplify voltage fluctuations. To ensure system stability, internationally, high and low voltage fault ride-through requirements have been proposed, which are to maintain grid-connected operation and provide reactive power support during voltage dips or rises to achieve rapid voltage recovery. Existing ride-through control technologies mainly include the control of doubly-fed and direct-drive wind turbine generators, DC bus voltage control of photovoltaic inverters, and reactive current injection strategies based on voltage deviation. Some control strategies adopt instantaneous power balance or virtual synchronous control principles to improve dynamic voltage response capabilities.

[0003] However, existing ride-through control methods generally suffer from insufficient adaptability to multiple operating conditions. Under conditions of alternating voltage dips and overvoltages, and mixed symmetrical and asymmetrical faults, traditional control logic often relies on a single threshold judgment, which cannot guarantee continuous switching between different voltage levels. Voltage state identification often uses fixed thresholds or amplitude criteria, which are difficult to accurately reflect the phase-to-phase voltage imbalance characteristics, resulting in unstable reactive power support response. Although some control structures have achieved the support function under voltage dips, their phase-to-phase coordination is poor under asymmetrical fault conditions, and the negative sequence voltage decoupling control is insufficient, which easily leads to inconsistent support direction or delayed response problems.

[0004] Furthermore, the control hierarchy of the cross-state machine is relatively simple, lacking a multi-level switching mechanism, which can cause control interruptions when the voltage transitions from low to high or from imbalance to steady state. The energy channel allocation method is also relatively simple, usually only constraining the DC bus voltage while ignoring the coordination between AC-side energy and DC-side power flow, which may lead to energy transfer imbalance. Summary of the Invention

[0005] In view of the above-mentioned problems, the present invention is proposed.

[0006] Therefore, the technical problem solved by this invention is that existing voltage fault ride-through control methods for new energy generator sets have problems such as low voltage state identification accuracy, separation of symmetrical and asymmetrical fault handling logic, discontinuous reactive power support command loading, delayed ride-through state switching response, and poor energy channel coordination. It also addresses the problem of how to achieve continuous high and low voltage ride-through and dynamic reactive power support coordinated control under multiple voltage levels and multiple operating conditions.

[0007] To address the aforementioned technical problems, this invention provides the following technical solution: a continuous high and low voltage fault ride-through response control method for new energy generating units, comprising: constructing a fault state identification mechanism based on generator terminal voltage characteristics; setting an optimal threshold range for high and low voltage ride-through entry and exit; continuously determining the unit's operating voltage state; generating a ride-through state identifier for each state; executing dynamic reactive power support control logic based on the optimal threshold range and ride-through state identifier; automatically loading reactive power support commands according to the voltage level by setting an optimal matching relationship between reactive current coefficients and active current coefficients; and driving the ride-through state machine to execute multi-level switching control based on the reactive power support commands, thereby coordinating and controlling the unit's stable active power output and adaptive reactive power support in real time through energy channel allocation logic. The optimal threshold range includes: constructing a voltage change trend sequence based on real-time sampling results of the terminal voltage; acquiring the voltage change rate and amplitude deviation within a continuous sampling period; determining the crossing judgment threshold with the stable change rate range as the boundary; setting a low voltage crossing exit threshold when the voltage change rate is in a stable range below a preset change rate; setting a low voltage crossing entry threshold when the voltage change rate is in a fast range above a preset change rate; setting a high voltage crossing entry threshold when the voltage rises above the upper limit of the stable range; and setting a high voltage crossing exit threshold when the voltage falls back to the lower limit of the stable range. The optimal threshold range for high and low voltage crossing is determined through dynamic sampling and boundary judgment of the voltage change trend.

[0008] As a preferred embodiment of the continuous high and low voltage fault ride-through response control method for new energy generating units described in this invention, the fault state identification mechanism includes: decomposing and comparing the positive sequence component, negative sequence component, and zero sequence component of the generator terminal voltage; constructing voltage state determination conditions based on the amplitude change rate and phase difference; and distinguishing between voltage drop, overvoltage, and unbalanced operating conditions. The voltage state determination conditions include symmetrical faults and asymmetrical faults.

[0009] As a preferred embodiment of the continuous high and low voltage fault ride-through response control method for new energy generating units described in this invention, the ride-through status identifier includes: numbering and identifying the unit's operating voltage status, classifying it into a ride-through level corresponding to the numbered identifier, distinguishing between symmetrical fault identifiers with uniform three-phase voltage drops and asymmetrical fault identifiers with unbalanced single-phase or two-phase voltage drops, generating a new identifier when a voltage status change is detected, and transmitting a switching signal to the dynamic reactive power support control logic.

[0010] As a preferred embodiment of the continuous high and low voltage fault ride-through response control method for new energy generating units described in this invention, the dynamic reactive power support control logic includes: when a symmetrical fault occurs, if the positive sequence voltage at the generator terminal is lower than 0.88 per unit, it is determined to enter the low voltage ride-through state; when the voltage recovers to above 0.9 per unit, it exits the low voltage ride-through state. During the low voltage period, the dynamic reactive power support control logic is executed, and the reactive power support current is obtained through the low voltage reactive current coefficient and the generator terminal voltage deviation, while maintaining the active current output according to the low voltage coefficient ratio; when the positive sequence voltage is higher than 1.125 per unit, it is determined to enter the high voltage ride-through state; when the voltage drops below 1.08 per unit, it exits the high voltage ride-through state. During the high voltage period, it is executed according to the high voltage reactive current coefficient and the generator terminal voltage deviation. Reactive current control maintains constant active power output. When an asymmetrical fault occurs, if the positive sequence voltage at the generator terminal is below 0.88 per unit and the imbalance flag is 1, the system enters low-voltage ride-through. When the voltage recovers to above 0.9 per unit and the imbalance flag is 0, the system exits low-voltage ride-through. During low-voltage periods, reactive power support current is obtained according to the low-voltage reactive current coefficient and the generator terminal voltage deviation to maintain proportional output of low-voltage active power current. When the positive sequence voltage at the generator terminal is above 1.125 per unit and the imbalance flag is 1, the system enters high-voltage ride-through. When the voltage is below 1.08 per unit and the imbalance flag is 0, the system exits high-voltage ride-through. During high-voltage periods, reactive current commands are calculated based on the high-voltage reactive current coefficient and the generator terminal voltage deviation to maintain constant active power output.

[0011] As a preferred embodiment of the continuous high and low voltage fault ride-through response control method for new energy units described in this invention, the reactive power support command includes: loading overall reactive power support according to voltage level under symmetrical faults, setting support commands for phase voltages respectively under asymmetrical faults, and adjusting the phase support ratio through negative sequence voltage feedback.

[0012] As a preferred embodiment of the continuous high and low voltage fault ride-through response control method for new energy units described in this invention, the ride-through state machine includes: performing multi-level switching control based on reactive power support instructions and support output signals; performing single-level switching control for symmetrical faults; performing phase-by-phase multi-level switching control for asymmetrical faults; forming a continuous control link between high and low voltage states; and performing synchronous driving for state maintenance and switching in conjunction with the time series of bus voltage changes.

[0013] As a preferred embodiment of the continuous high and low voltage fault ride-through response control method for new energy units described in this invention, the energy channel allocation logic includes: distinguishing the total power channel under symmetrical faults and the phase-to-phase power channel under asymmetrical faults based on the multi-level switching control of the ride-through state machine; coordinating the energy allocation between the DC bus and the AC side; and setting the energy transmission path and control priority under voltage drop, overvoltage, and imbalance conditions.

[0014] Another objective of this invention is to provide a continuous high and low voltage fault ride-through response control system for new energy generating units. This system can achieve accurate voltage status identification and multi-level switching control through three collaborative schemes: fault status identification, dynamic reactive power support control, and ride-through coordination control. This solves the problems of discontinuous support commands, untimely fault response, and lack of unified energy distribution logic in existing ride-through control technologies under multiple operating conditions.

[0015] As a preferred embodiment of the continuous high and low voltage fault ride-through response control system for new energy generating units described in this invention, the system includes: a fault state identification module, a dynamic reactive power support control module, and a ride-through coordination control module. The fault state identification module is used to construct voltage state judgment conditions based on the positive sequence, negative sequence, and zero sequence component analysis of the generator terminal voltage, identify voltage dips, overvoltages, and unbalanced operation, and generate corresponding ride-through state identifiers. The dynamic reactive power support control module is used to execute dynamic reactive power support control logic under different voltage levels according to the ride-through state identifiers, load support commands under high and low voltage and symmetrical and asymmetrical faults, and perform dynamic hierarchical control of the reactive power support direction and amplitude. The ride-through coordination control module is used to receive the dynamic reactive power support output signal, drive the ride-through state machine to perform multi-level switching control, coordinate the power flow direction of the DC bus and AC side based on the energy channel allocation logic, and uniformly control the continuous ride-through of high and low voltages.

[0016] Another object of the present invention is to provide a continuous high and low voltage fault ride-through response control device for new energy generating units, including a memory and a processor. The memory stores a computer program, and the processor executes the computer program to implement the steps of the continuous high and low voltage fault ride-through response control method for new energy generating units.

[0017] Another object of the present invention is to provide a storage medium for continuous high and low voltage fault ride-through response control of a new energy unit, wherein a computer program is stored thereon, and when the computer program is executed by a processor, the steps of the continuous high and low voltage fault ride-through response control method for the new energy unit are implemented.

[0018] The beneficial effects of this invention are as follows: The continuous high and low voltage fault ride-through response control method for new energy generating units provided by this invention achieves accurate voltage state determination and multi-condition identification by constructing a fault state identification mechanism based on the characteristics of the generator terminal voltage; it realizes continuous switching of reactive power support between high and low voltage and symmetrical and asymmetrical faults through dynamic reactive power support control logic; and it realizes synchronous switching of multi-level ride-through states and unified energy flow allocation through the coordinated control of the ride-through state machine and energy channel allocation logic. This invention achieves better results in terms of voltage ride-through continuity, dynamic response of reactive power support, and energy allocation coordination. Attached Figure Description

[0019] To more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings used in the following description of the embodiments will be briefly introduced. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0020] Figure 1 The above is an overall flowchart of the continuous high and low voltage fault ride-through response control method for new energy units provided in Embodiment 1 of the present invention.

[0021] Figure 2 The rapid high and low voltage continuous ride-through curve is shown in Embodiment 2 of the present invention for the continuous high and low voltage fault ride-through response control method of the new energy unit.

[0022] Figure 3 The slow high and low voltage continuous ride-through curve is shown in Embodiment 2 of the present invention for the continuous high and low voltage fault ride-through response control method of the new energy unit.

[0023] Figure 4 The diagram shows the positive sequence components of the generator terminal voltage and the positive sequence component of the reactive current during the rapid high and low voltage continuous ride-through response control method for new energy generating units provided in Embodiment 2 of the present invention.

[0024] Figure 5 The diagram shows the positive sequence components of the generator terminal voltage and the positive sequence component of the active power during the rapid high and low voltage continuous ride-through of the new energy unit continuous high and low voltage fault ride-through response control method provided in Embodiment 2 of the present invention.

[0025] Figure 6 The diagram shows the positive sequence components of the generator terminal voltage and the positive sequence component of the active current during the rapid high and low voltage continuous ride-through of the new energy unit continuous high and low voltage fault ride-through response control method provided in Embodiment 2 of the present invention.

[0026] Figure 7The diagram shows the positive sequence components of the generator terminal voltage and the positive sequence component of the reactive current during the slow high and low voltage continuous ride-through of the new energy unit continuous high and low voltage fault ride-through response control method provided in Embodiment 2 of the present invention.

[0027] Figure 8 The diagram shows the positive sequence components of the generator terminal voltage and the positive sequence component of the active power during the slow high and low voltage continuous ride-through of the new energy unit continuous high and low voltage fault ride-through response control method provided in Embodiment 2 of the present invention.

[0028] Figure 9 The diagram shows the positive sequence components of the generator terminal voltage and the positive sequence component of the active current during the slow high and low voltage continuous ride-through of the new energy generator unit according to Embodiment 2 of the present invention. Detailed Implementation

[0029] To make the above-mentioned objects, features, and advantages of the present invention more apparent and understandable, specific embodiments of the present invention will be described in detail below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of them. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort should fall within the protection scope of the present invention.

[0030] Example 1, referring to Figure 1 As an embodiment of the present invention, a continuous high and low voltage fault ride-through response control method for new energy generating units is provided, comprising: S1: Construct a fault state identification mechanism based on the characteristics of the generator terminal voltage, set the optimal threshold range for high and low voltage cross-through entry and exit, continuously determine the operating voltage state of the unit, and generate a cross-through state identifier for each state.

[0031] Furthermore, the fault state identification mechanism 100 includes decomposing and comparing the positive sequence component, negative sequence component, and zero sequence component of the terminal voltage, constructing voltage state judgment conditions based on the amplitude change rate and phase difference, and distinguishing between voltage drop, overvoltage, and unbalanced operating conditions; the voltage state judgment conditions include symmetrical faults and asymmetrical faults.

[0032] It should be noted that after the three-phase voltage signal at the generator terminal of the new energy unit is sampled, it passes through the fault state identification mechanism 100. First, the positive sequence, negative sequence and zero sequence voltage components are extracted by the symmetrical component decomposition algorithm. The positive sequence component is used to characterize the normal symmetrical operation characteristics; the negative sequence component is used to identify the asynchronous component caused by the phase voltage imbalance; and the zero sequence component is used to detect the common mode drift of the three phase voltages.

[0033] The optimal threshold range includes: constructing a voltage change trend sequence based on real-time sampling results of the terminal voltage; acquiring the voltage change rate and amplitude deviation within a continuous sampling period; and determining the crossing judgment threshold with the stable change rate range as the boundary. When the voltage change rate is in a stable range below a preset change rate, it is set as a low voltage crossing exit threshold; when the voltage change rate is in a rapid range above a preset change rate, it is set as a low voltage crossing entry threshold. When the voltage rises above the upper limit of the stable range, it is set as a high voltage crossing entry threshold; and when the voltage falls back to the lower limit of the stable range, it is set as a high voltage crossing exit threshold. The optimal threshold range for high and low voltage crossing is determined through dynamic sampling and boundary judgment of the voltage change trend.

[0034] By acquiring the amplitude change rate and phase difference change trend of each component, a voltage state judgment matrix is ​​established. When the amplitude of the positive sequence component is lower than the per-unit value of 0.88 and accompanied by an increase in the negative sequence component, it is judged as a low voltage asymmetric fault. When the positive sequence component is higher than the per-unit value of 1.125 and the negative sequence component is small, it is judged as a high voltage symmetric fault. When the zero sequence component changes abruptly and the phase shift is inconsistent, it is identified as an unbalanced overvoltage or drop state. The judgment result is output as a voltage state code through logical operation, which is used to generate a cross-state identifier.

[0035] It should be noted that the ride-through status identification includes numbering the unit's operating voltage status, classifying it into the ride-through level corresponding to the number, distinguishing between symmetrical fault identification of uniform three-phase voltage drop and asymmetrical fault identification of unbalanced single-phase or two-phase voltage drop, generating a new identification when a voltage status change is detected, and transmitting a switching signal to the dynamic reactive power support control logic 200.

[0036] It should also be noted that by combining positive sequence, negative sequence, and zero sequence components with amplitude change rate and phase difference, a multi-dimensional determination of voltage state is achieved, avoiding the misjudgment problem of traditional single threshold triggering method in asymmetrical fault scenarios. By setting cross-pass status identifier and cross-pass level code, the identification result can directly drive subsequent control logic, forming a continuous transition from the measurement domain to the control domain.

[0037] S2: Execute dynamic reactive power support control logic (200) based on the optimal threshold range and cross-state identifier. By setting the optimal matching relationship between reactive current coefficient and active current coefficient, the reactive power support command is automatically loaded according to the voltage level.

[0038] Furthermore, the dynamic reactive power support control logic 200 includes the following: when the current fault is symmetrical, if the positive sequence voltage at the generator terminal is lower than the per-unit value of 0.88, it is determined to enter the low voltage ride-through state; when the voltage recovers to above the per-unit value of 0.9, it exits the low voltage ride-through state. During the low voltage period, the dynamic reactive power support control logic is executed to obtain the reactive power support current through the low voltage reactive current coefficient and the generator terminal voltage deviation, while maintaining the active current output according to the low voltage coefficient ratio.

[0039] When the positive sequence voltage is higher than 1.125 per unit, it is determined to enter the high voltage ride-through state; when the voltage drops to below 1.08 per unit, it exits the high voltage ride-through state. During the high voltage period, reactive current control is performed according to the high voltage reactive current coefficient and the terminal voltage deviation to keep the active power output unchanged.

[0040] When the current condition is under asymmetrical fault, if the positive sequence voltage at the generator terminal is lower than 0.88 per unit and the unbalance flag is 1, it is determined to enter the low voltage ride-through stage; when the voltage recovers to above 0.9 per unit and the unbalance flag is 0, it exits the low voltage ride-through stage; during the low voltage period, the reactive power support current is obtained according to the low voltage reactive current coefficient and the generator terminal voltage deviation to maintain the low voltage active current output proportionally.

[0041] When the positive sequence voltage at the generator terminal is higher than 1.125 per unit and the unbalance flag is 1, it enters high voltage ride-through; when the voltage is lower than 1.08 per unit and the unbalance flag is 0, it exits high voltage ride-through; during high voltage, the reactive current command is calculated based on the high voltage reactive current coefficient and the generator terminal voltage deviation to keep the active power output unchanged.

[0042] It should also be noted that the low-through reactive current is expressed as: , Low-pass active current is expressed as: , High-voltage reactive current is represented as: , in, This represents the change in reactive current during low-voltage ride-through. This represents the reactive power undervoltage current factor during the low-voltage ride-through phase, with a range set from 1.5 to 1.8. Represented as the per-unit value of the terminal voltage. Indicates the low voltage value at the machine terminal. This represents the rated current of the fan, used as a normalized reference value. This represents the reactive current setpoint before high-voltage transmission. This represents the change in active current during low-voltage ride-through. The active low-voltage ride-through current factor represents the low-voltage ride-through phase, and is set to a range of 0.5 to 0.7. This represents the active current of the direct-drive wind turbine before the voltage drop. This represents the change in reactive current during high-voltage ride-through. This represents the reactive high-voltage ride-through current factor, with a range set from 1.5 to 3.0. This indicates the high voltage value at the machine terminal.

[0043] It should be noted that the reactive power support command includes loading overall reactive power support according to voltage level under symmetrical faults, setting support commands for phase voltages separately under asymmetrical faults, and adjusting the phase support ratio through negative sequence voltage feedback.

[0044] It should also be noted that the control system of the new energy unit monitors the terminal voltage signal in real time and calls the corresponding reactive power support parameters according to the cross-through status indicator. When the voltage is detected to enter the low-voltage cross-through range, the control logic immediately loads the low-voltage reactive power support command and injects the obtained reactive power support current into the grid connection point to maintain voltage recovery. When the voltage gradually rises to exit the low-voltage cross-through range, the control logic automatically weakens the support strength and returns to normal operation.

[0045] When the voltage exceeds the high-voltage range, the control logic switches to high-voltage support mode to suppress the voltage rise trend by absorbing reactive current. When the voltage returns to normal, the system resets to the initial state. For asymmetrical faults, the reactive current ratio of each phase is adjusted in real time by the negative sequence voltage component to achieve phase-by-phase support and inter-phase compensation. The entire control process maintains logical continuity under the synchronous drive of the cross-state machine, ensuring the consistency between voltage state changes and support switching.

[0046] S3: Based on the reactive power support command, drive the through state machine to execute multi-level switching control (300), and coordinate the stable active power output and adaptive reactive power support of the unit in real time through the energy channel distribution logic (400).

[0047] Furthermore, the state machine includes multi-level switching control 300 based on reactive power support instructions and support output signals, single-level switching control for symmetrical faults, phase-by-phase multi-level switching control for asymmetrical faults, forming a continuous control link between high and low voltage states, and synchronously driving state maintenance and switching by combining the time series of bus voltage changes.

[0048] It should be noted that the energy channel allocation logic 400 includes, based on the multi-level switching control 300 of the cross-state machine, distinguishing the total power channel under symmetrical faults and the phase-to-phase power channel under asymmetrical faults, coordinating the energy allocation between the DC bus and the AC side, and setting the energy transmission path and control priority under voltage drop, overvoltage and imbalance conditions.

[0049] It should also be noted that the state machine receives the support output signal and reactive power support command from the dynamic reactive power support control logic 200. Based on the combination of different voltage levels and the imbalance flag, it determines the switching path. When the generator terminal voltage rises from the low-voltage range to the recovery range and the imbalance flag changes from 1 to 0, the state machine determines that the low-voltage ride-through exit condition is met and immediately performs a single-stage switch from low-voltage ride-through to normal operation. When the voltage continues to rise above the high-voltage range, the state machine triggers the high-voltage ride-through support logic and automatically enters the high-voltage ride-through state. When the voltage drops below 1.08 per-unit value, the state machine recognizes the high-voltage ride-through exit and returns to the steady-state control range. Through continuous switching, the state machine achieves multi-stage smooth transitions in different voltage ranges, avoiding sudden changes in control quantities during voltage fluctuations.

[0050] It should also be noted that, for asymmetrical faults, the through-state machine independently performs voltage sampling and flag identification for each phase in phase-separated mode. By tracking the negative sequence component and phase-to-phase voltage deviation in real time, the three-phase voltage state is divided into independent control branches, and corresponding reactive power support commands are loaded for each branch. At this time, the through-state machine uses the phase-separated support output as the driving signal to form a multi-level switching control 300 operation. When the voltage of a single phase or two phases recovers to the point of exiting the low-voltage range, the state machine performs a partial reset for that phase channel, while the other phases remain in the support state, thus realizing multi-level asynchronous switching control under asymmetrical faults.

[0051] Example 2, refer to Figures 1-9 As an embodiment of the present invention, a continuous high and low voltage fault ride-through response control method for new energy generating units is provided. In order to verify the beneficial effects of the present invention, scientific demonstration is carried out through economic benefit calculation and simulation experiments.

[0052] First, the test system was built based on the semi-physical controller: the impedance L1 was cut off, a controlled voltage source was added to bus 71, and the new energy unit was connected to the controlled voltage source through a 4-level transformer. At this time, the short-circuit ratio of the new energy unit was 2.22.

[0053] For reference Figure 1 As shown, continuous high and low voltage fault ride-through tests were conducted on the new energy power generation units. The test areas are marked with red circles A1 and A2 to test the high and low voltage continuous ride-through stability and response speed of the new energy power generation units.

[0054] The active power of the new energy unit was set to 0.9 pu, and the reactive power to 0.3 pu. After stable operation for 2 seconds, the voltage of bus 71 was adjusted to 1.0 pu. The voltage curves of bus 71 are shown in the reference figures. Figure 2 , Figure 3 As shown, the three-phase voltage and current of the new energy generator terminal bus and the S-side of the high-voltage side bus of the transformer substation are recorded at a sampling rate of 10kHz.

[0055] Operating Condition 1: When the bus voltage is as follows: Figure 2 The rapid high and low voltage continuous crossover curves shown have a voltage variation range between 0.2 and 1.3 pu, with each low and high voltage lasting 100 ms and the transition time from low to high voltage not exceeding 10 ms.

[0056] Operating Condition 2: When the bus voltage is as follows: Figure 3 The slow high and low voltage continuous crossover curve shown has a voltage variation range between 0.2 and 1.3 pu, with each low and high voltage lasting 100 ms, and the transition time from low to high voltage being 55 to 65 ms.

[0057] Test results: Operating Condition 1: As per reference Figure 4-6 As shown, during the rapid high and low voltage continuous ride-through test, the terminal voltage of the machine changed rapidly twice between low and high voltages between 0.2 and 1.3 pu. The direct-drive fan entered the continuous high and low voltage ride-through process and maintained stable operation during the fault process.

[0058] Operating Condition 2: As per reference Figure 7-9 As shown, during the slow high and low voltage continuous ride-through test, the terminal voltage of the machine undergoes two consecutive slow changes between low and high voltages between 0.2 and 1.3 pu. The direct-drive fan enters the continuous high and low voltage ride-through process and maintains stable operation during the fault process.

[0059] The results of the high and low voltage continuous ride-through test show that, with a short-circuit ratio of 2.22 at the generator terminals, the initial apparent power is 0.95 pu. At the moment of low-to-high voltage transition, the effective value of the positive sequence component of the voltage fundamental wave is less than 1.286 pu, and the instantaneous value of the three-phase line voltage reaches a maximum of 1.411 pu. The tested direct-drive wind turbine can maintain grid-connected operation during various high and low voltage continuous ride-through test conditions.

[0060] Example 3, an embodiment of the present invention, provides a continuous high and low voltage fault ride-through response control system for new energy generating units, including a fault status identification module, a dynamic reactive power support control module, and a ride-through coordination control module.

[0061] The fault status identification module is used to construct voltage status judgment conditions based on the positive sequence, negative sequence and zero sequence component analysis of the terminal voltage, identify voltage drop, overvoltage and unbalanced operation, and generate corresponding ride-through status identifiers.

[0062] The dynamic reactive power support control module is used to execute dynamic reactive power support control logic under different voltage levels based on the cross-state indicator, load support commands under high and low voltage and symmetrical and asymmetrical faults, and perform dynamic hierarchical control of reactive power support direction and amplitude.

[0063] The crossing coordination control module is used to receive the dynamic reactive power support output signal, drive the crossing state machine to perform multi-level switching control, coordinate the power flow direction of the DC bus and AC side based on the energy channel distribution logic, and uniformly control the continuous crossing of high and low voltage.

[0064] This embodiment also provides a computer device, including a memory and a processor. The memory stores a computer program, and when the processor executes the computer program, it implements a personnel positioning safety management visualization analysis system as proposed in the above embodiment.

[0065] This embodiment also provides a computer-readable storage medium storing a computer program thereon, which, when executed by a processor, implements a personnel positioning safety management visualization analysis system as proposed in the above embodiment.

[0066] If the aforementioned functions are implemented as software functional units and sold or used as independent products, they can be stored in a computer-readable storage medium. Based on this understanding, the technical solution of this invention, essentially, or the part that contributes to the prior art, or a portion of the technical solution, can be embodied in the form of a software product. This computer software product is stored in a storage medium and includes several instructions to cause a computer device (which may be a personal computer, server, or network device, etc.) to execute all or part of the steps of the methods described in the various embodiments of this invention. The aforementioned storage medium includes various media capable of storing program code, such as USB flash drives, portable hard drives, read-only memory (ROM), random access memory (RAM), magnetic disks, or optical disks.

[0067] The logic and / or steps represented in the flowchart or otherwise described herein, for example, can be considered as a sequenced list of executable instructions for implementing logical functions, and can be embodied in any computer-readable medium for use by, or in conjunction with, an instruction execution system, apparatus, or device (such as a computer-based system, a processor-including system, or other system that can fetch and execute instructions from, an instruction execution system, apparatus, or device). For the purposes of this specification, "computer-readable medium" can be any means that can contain, store, communicate, propagate, or transmit programs for use by, or in conjunction with, an instruction execution system, apparatus, or device.

[0068] More specific examples of computer-readable media (a non-exhaustive list) include: electrical connections (electronic devices) having one or more wires, portable computer disk drives (magnetic devices), random access memory (RAM), read-only memory (ROM), erasable and editable read-only memory (EPROM or flash memory), fiber optic devices, and portable optical disc read-only memory (CDROM). Furthermore, computer-readable media can even be paper or other suitable media on which the program can be printed, because the program can be obtained electronically, for example, by optically scanning the paper or other medium, followed by editing, interpreting, or otherwise processing as necessary, and then stored in computer memory.

[0069] It should be understood that various parts of the present invention can be implemented in hardware, software, firmware, or a combination thereof. In the above embodiments, multiple steps or methods can be implemented in software or firmware stored in memory and executed by a suitable instruction execution system. For example, if implemented in hardware, as in another embodiment, it can be implemented using any one or a combination of the following techniques known in the art: discrete logic circuits having logic gates for implementing logical functions on data signals, application-specific integrated circuits (ASICs) having suitable combinational logic gates, programmable gate arrays (PGAs), field-programmable gate arrays (FPGAs), etc.

[0070] It should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and not to limit it. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the spirit and scope of the technical solutions of the present invention, and all such modifications or substitutions should be covered within the scope of the claims of the present invention.

Claims

1. A method for continuous high-low voltage fault ride-through response control of a new energy unit, characterized in that, The method comprises the following steps: A fault state recognition mechanism (100) based on machine terminal voltage characteristics is constructed, optimal threshold intervals for entering and exiting low voltage ride through are set, the operation voltage state of the unit is continuously determined, and a ride through state identifier for each state is generated; A dynamic reactive power support control logic (200) is executed based on the optimal threshold intervals and the ride through state identifier, the optimal matching relationship between the reactive current coefficient and the active current coefficient is set, and the reactive power support instruction is automatically loaded according to the voltage level; Based on the reactive power support instruction, a multi-stage switching control (300) is executed by the ride through state machine, and the stable active output and adaptive reactive power support of the unit are real-time coordinated and controlled through the distribution logic (400) of the energy channel; The optimal threshold interval comprises the following steps: a voltage change trend sequence is constructed according to the real-time sampling result of the machine terminal voltage, the change rate and amplitude deviation of the voltage are obtained in the continuous sampling period, and the ride through determination threshold is determined by taking the change rate stable interval as the boundary; when the voltage change rate is in the stable interval lower than the preset change rate, the low voltage ride through exit threshold is set; when the voltage change rate is in the fast interval higher than the preset change rate, the low voltage ride through entry threshold is set; when the voltage rising trend exceeds the upper limit of the stable interval, the high voltage ride through entry threshold is set; when the voltage falls to the lower limit of the stable interval, the high voltage ride through exit threshold is set, and the optimal threshold interval of the high and low voltage ride through is determined by dynamically sampling the voltage change trend and boundary judgment.

2. The method of claim 1, wherein the method further comprises: The fault state recognition mechanism (100) comprises the following steps: The positive sequence component, negative sequence component and zero sequence component of the machine terminal voltage are decomposed and compared, the voltage state determination condition is constructed according to the amplitude change rate and phase difference, and the voltage drop, overvoltage and unbalanced operation condition are distinguished. The voltage state determination condition comprises the following steps: the symmetric fault and the asymmetric fault.

3. The method according to claim 1 or 2, characterized in that: The ride through state identifier comprises the following steps: The operation voltage state of the unit is numbered and identified, and is divided into the ride through level corresponding to the number identification, the symmetric fault identifier of the uniform drop of three-phase voltage and the asymmetric fault identifier of the unbalanced drop of single-phase and two-phase are distinguished, a new identifier is generated when the voltage state changes, and a switching signal is transmitted to the dynamic reactive power support control logic (200).

4. The method of claim 3, wherein the method further comprises: The dynamic reactive power support control logic (200) comprises the following steps: When the current is in the symmetric fault, if the positive sequence voltage at the machine terminal is lower than 0.88 per unit, it is determined to enter the low ride through state; when the voltage is restored to above 0.9 per unit, it is exited from the low voltage ride through, and the dynamic reactive power support control logic (200) is executed during the low voltage period, the reactive power support current is obtained through the low voltage reactive current coefficient and the voltage deviation at the machine terminal, and the active current is maintained to be output in proportion to the low voltage coefficient; When the positive sequence voltage is higher than 1.125 per unit, it is determined to enter the high ride through state; when the voltage drops below 1.08 per unit, it is exited from the high voltage ride through, and the reactive current control is executed according to the high voltage reactive current coefficient and the voltage deviation at the machine terminal during the high voltage period, and the active output is maintained to be unchanged. When the machine terminal positive sequence voltage is lower than 0.88 per unit and the unbalance flag is 1 in the current asymmetric fault, it is determined that low voltage ride through is entered; when the voltage is restored to above 0.9 per unit and the unbalance flag is 0, the low voltage ride through is exited; during the low voltage, the reactive power support current is obtained according to the low voltage reactive power current coefficient and the machine terminal voltage deviation, and the low voltage active power current is output in proportion; When the machine terminal positive sequence voltage is higher than 1.125 per unit and the unbalance flag is 1, high voltage ride through is entered; when the voltage is lower than 1.08 per unit and the unbalance flag is 0, the high voltage ride through is exited; during the high voltage, the reactive power current instruction is calculated according to the high voltage reactive power current coefficient and the machine terminal voltage deviation, and the active power output is kept unchanged.

5. The method of claim 1, 2, 4, wherein the method is characterized in that: The reactive power support instruction comprises, The overall reactive power support is loaded according to the voltage level under symmetric fault, and the support instruction is set for each phase voltage under asymmetric fault, and the support proportion between phases is adjusted through negative sequence voltage feedback.

6. The method of claim 5, wherein the method further comprises: The ride through state machine comprises, Multi-stage switching control (300) is performed according to the reactive power support instruction and the support output signal, single-stage switching control is performed on symmetric fault, multi-stage switching control is performed on asymmetric fault, a continuous control link is formed between high and low voltage states, and state keeping and synchronous driving of switching are performed in combination with the time sequence of bus voltage change.

7. The continuous high and low voltage fault ride-through response control method for new energy generating units as described in any one of claims 1, 2, 4, and 6, characterized in that: The distribution logic (400) of the energy channel comprises, The total power channel under symmetric fault and the inter-phase power channel under asymmetric fault are distinguished according to the multi-stage switching control (300) of the ride through state machine, the energy distribution of the DC bus and the AC side is coordinated, and the energy transmission path and the control priority under voltage drop, overvoltage and unbalance conditions are set.

8. A system for continuous high and low voltage fault ride through response control of a new energy unit, adopting the method for continuous high and low voltage fault ride through response control of a new energy unit according to any one of claims 1-7, characterized in that: The fault state identification module, the dynamic reactive power support control module and the ride through coordination control module are included. The fault state identification module is used for analyzing the positive sequence, negative sequence and zero sequence components based on the machine terminal voltage, constructing voltage state determination conditions, identifying voltage drop, overvoltage and unbalanced operation, and generating corresponding ride through state identification; The dynamic reactive power support control module is used for performing dynamic reactive power support control logic (200) under different voltage levels according to the ride through state identification, loading support instructions under high and low voltage and symmetric and asymmetric fault, and performing dynamic grading control on the direction and amplitude of reactive power support; The ride through coordination control module is used for receiving the dynamic reactive power support output signal, driving the ride through state machine to perform multi-stage switching control (300), coordinating the power flow direction of the DC bus and the AC side based on the distribution logic (400) of the energy channel, and uniformly controlling the continuous ride through of high and low voltage. 9.A computer device, comprising a memory and a processor, wherein the memory stores a computer program, and the computer device is configured to perform the method according to any one of claims 1-8 when the computer program is executed by the processor. The processor executes the computer program to implement the steps of the new energy unit continuous high and low voltage fault ride through response control method in any one of claims 1 to 7.

10. A computer-readable storage medium having stored thereon a computer program, characterized in that, The computer program is executed by the processor to implement the steps of the new energy unit continuous high and low voltage fault ride through response control method in any one of claims 1 to 7.

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