A method and system for adaptive identification of splitting section for high-proportion new energy power grid

Abstract

The application provides a split section adaptive identification method and system for a high-proportion new energy power grid, and belongs to the technical field of power grid split protection; the method comprises the following steps: determining a primary section from the power grid according to a coherence constraint condition; screening a secondary section by means of instability comprehensive index sorting and in combination with a subsystem operation constraint condition; positioning a line protection device closest to the electrical distance of the primary section and the secondary section respectively according to a priority order, and determining the time of issuing a release blocking signal through real-time monitoring; starting a delay timer after the release blocking signal is issued, and executing a split action by controlling the corresponding line protection device. The application can ensure that the split is implemented quickly to isolate the fault on the basis of ensuring that the power outage area is as small as possible.

Description

Technical Field

[0001] This invention belongs to the field of power grid disconnection protection technology, and particularly relates to an adaptive identification method and system for disconnection sections in power grids with a high proportion of new energy sources. Background Technology

[0002] The statements in this section are merely background information related to the present invention and do not necessarily constitute prior art.

[0003] As a crucial component of the "three lines of defense" in power systems, grid disconnection can divide the power system into several stable, non-interfering subsystems after a fault occurs, thereby preventing fault propagation and large-scale blackouts. It is an effective means of preventing further escalation of accidents. In new power systems, the diversification of energy and load forms can reduce the defensive capabilities of the second line of defense and increase the burden on the third line of defense. For example, the volatility and intermittency of renewable energy output can exacerbate the risk of unplanned grid disconnection. Grid disconnection faces new challenges. In extreme cases, how to rationally select disconnection sections and quickly isolate faults in complex grid structures has become an urgent problem to be solved.

[0004] Traditional disconnection methods predetermine the disconnection location and operating conditions of the disconnection device through offline calculations, and determine the device's operating time based on local measurement information. However, this method relies on fixed setpoints and preset sections, making it difficult to adapt to changes in grid operation. Therefore, most existing technologies choose optimization-based methods to obtain the final disconnection section, but this method has the following technical drawbacks:

[0005] (1) After the new energy is connected, the grid becomes more complex and it is impossible to achieve a new balance by disconnecting a single section. The sections that are suitable for disconnection can form the optimal section set. If all sections that meet the conditions are disconnected at the same time, problems such as too many subsystems and weak connections may occur, which will disrupt the power balance and induce new frequency and voltage problems.

[0006] (2) Existing optimization-based methods result in a definite solution section. With the widespread access of new energy sources, the fluctuation and uncertainty of their output can easily lead to frequent changes in the oscillation center after a fault, which in turn leads to frequent changes in the optimal solution section. The fault isolation cannot be achieved in time at the frequently updated optimal section. Summary of the Invention

[0007] To overcome the shortcomings of the prior art, the present invention provides an adaptive identification method and system for disconnection sections in high-proportion renewable energy power grids, which can ensure rapid disconnection to isolate faults while minimizing the power outage area.

[0008] To achieve the above objectives, one or more embodiments of the present invention provide the following technical solutions:

[0009] The first aspect of the present invention provides an adaptive identification method for disconnection sections in a high-proportion renewable energy power grid.

[0010] An adaptive identification method for disconnection sections in high-proportion renewable energy power grids includes:

[0011] Based on the preset homogeneity constraints, determine the first-level cross-section from the power grid;

[0012] Based on the changes in electrical quantities before and after the fault, the comprehensive instability index of each potential section is calculated, and the sections are sorted from high to low according to the comprehensive instability index. Combined with the subsystem operation constraints, secondary sections that meet the conditions are selected from the sorted sections.

[0013] For the selected primary and secondary cross sections, locate the line protection devices that are closest to their respective electrical distances according to priority order;

[0014] The phase voltage and line current of the line where the line protection device is located are monitored. If a sudden change in both phase voltage and line current is detected, a signal to release the blocking is generated.

[0015] After the unlocking signal is issued, a delay timer is started. If the phase voltage and line current remain in an abnormal state within the delay time, the corresponding line protection device is controlled to perform a disconnection action.

[0016] Furthermore, the homogeneity constraints include the homogeneity constraints of the generators and the asynchronous isolation constraints between the generator groups.

[0017] Furthermore, the instability comprehensive index is calculated by weighting multiple electrical quantity change indicators, which include active power change, voltage amplitude change, voltage phase angle difference change rate, and frequency change rate difference.

[0018] Furthermore, the operating constraints of the subsystem include: the subsystem's power generation capacity is not less than the sum of load demand and network loss; the voltage of each node in the subsystem is within a preset allowable range; the subsystem's frequency is within a preset allowable range; and the output of each power generation device is within the operating limit.

[0019] Furthermore, the electrical distance is calculated and determined based on the per-unit value of the line impedance.

[0020] Furthermore, the criteria for determining whether the phase voltage and line current change simultaneously are: the instantaneous value of the phase voltage exceeds the preset normal operating range, and the instantaneous value of the line current exceeds the preset normal operating range.

[0021] Furthermore, the delay time is used to distinguish between transient disturbances and permanent faults.

[0022] A second aspect of the present invention provides an adaptive identification system for disconnection sections in a high-proportion renewable energy power grid.

[0023] An adaptive identification system for disconnection sections in high-proportion renewable energy power grids includes:

[0024] The primary section screening module is configured to determine primary sections from the power grid based on preset homogeneity constraints.

[0025] The secondary section screening module is configured to: calculate the instability comprehensive index of each potential section based on the changes in electrical quantities before and after the fault, sort the sections from high to low according to the instability comprehensive index, and select the secondary sections that meet the conditions from the sorted sections in combination with the subsystem operation constraints.

[0026] The priority order sorting module is configured to: for the selected primary section and secondary section, locate the line protection device that is closest to their respective electrical distance according to the priority order;

[0027] The release blocking control module is configured to: monitor the phase voltage and line current of the line where the line protection device is located; if a sudden change in both phase voltage and line current is detected, generate a release blocking signal.

[0028] The disconnection action execution module is configured to: start a delay timer after the release blocking signal is issued; if the phase voltage and line current remain in an abnormal state within the delay time, control the corresponding line protection device to perform the disconnection action.

[0029] A third aspect of the present invention provides a computer-readable storage medium having a program stored thereon, which, when executed by a processor, implements the steps in the adaptive identification method for disconnection sections of a high-proportion renewable energy power grid as described in the first aspect of the present invention.

[0030] The fourth aspect of the present invention provides an electronic device including a memory, a processor, and a program stored in the memory and executable on the processor, wherein the processor executes the program to implement the steps in the adaptive identification method for disconnection sections of a high-proportion renewable energy grid as described in the first aspect of the present invention.

[0031] The above one or more technical solutions have the following beneficial effects:

[0032] (1) Based on preset synchronization constraints, this invention determines primary cross-sections from the power grid; based on changes in electrical quantities before and after a fault, it calculates the comprehensive instability index of each potential cross-section, and sorts them from high to low according to the comprehensive instability index. Combined with subsystem operation constraints, it selects secondary cross-sections that meet the conditions from the sorted cross-sections. This invention, through this method of separation considering cross-section priority, can separate cross-sections from high to low priority, thereby maximizing the limitation of the expansion of the power outage range.

[0033] (2) This invention monitors the phase voltage and line current of the line where the line protection device is located. When a sudden change in both phase voltage and line current is detected, a signal to release the blocking is generated. Thus, based on existing line protection devices, this invention adds a blocking design. According to the priority of the cross-section from high to low, after a fault, the line protection device closest to the selected cross-section is selected to release the blocking. The protection device then operates to isolate the fault, achieving a balance between the optimal selection of the cross-section and the speed of fault isolation.

[0034] Advantages of additional aspects of the invention will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. Attached Figure Description

[0035] The accompanying drawings, which form part of this invention, are used to provide a further understanding of the invention. The illustrative embodiments of the invention and their descriptions are used to explain the invention and do not constitute an improper limitation of the invention.

[0036] Figure 1 This is a flowchart of the adaptive identification method for the disconnection section of a high-proportion renewable energy power grid in Embodiment 1 of the present invention. Detailed Implementation

[0037] It should be noted that the following detailed descriptions are exemplary and intended to provide further illustration of the invention. Unless otherwise specified, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains.

[0038] It should be noted that the terminology used herein is for the purpose of describing particular implementations only and is not intended to limit the exemplary implementations of the present invention.

[0039] Where there is no conflict, the embodiments and features in the embodiments of the present invention can be combined with each other.

[0040] The overall approach proposed in this invention is as follows: This invention provides an adaptive identification method for disconnection sections in high-proportion renewable energy power grids. This method can be divided into three key stages: section priority ranking, disconnection blocking control, and action execution. First, section priorities are defined based on the basic constraints to be met during disconnection and the section's susceptibility to instability. Then, based on the line protection device, disconnection blocking is set according to the detected line current and phase voltage. Finally, the line protection device is located based on the electrical distance, and the action is executed after a delay.

[0041] Example 1

[0042] This embodiment discloses an adaptive identification method for disconnection sections in high-proportion renewable energy power grids.

[0043] like Figure 1 As shown, the adaptive identification method for the disconnection section of a high-proportion renewable energy power grid includes:

[0044] Step S1: Determine the first-level cross-section from the power grid according to the preset homogeneity constraints;

[0045] Step S2: Based on the changes in electrical quantities before and after the fault, calculate the comprehensive instability index of each potential section, and sort them from high to low according to the comprehensive instability index. Combined with the subsystem operation constraints, select the secondary sections that meet the conditions from the sorted sections. For the selected primary and secondary sections, locate the line protection device that is closest to them in terms of priority.

[0046] Step S3: Monitor the phase voltage and line current of the line where the line protection device is located. If a sudden change in both phase voltage and line current is detected, generate a signal to release the blocking.

[0047] Step S4: After the unlocking signal is issued, start the delay timer. If the phase voltage and line current remain in an abnormal state within the delay time, control the corresponding line protection device to perform the disconnection action.

[0048] Based on the above process, this invention can ensure rapid disconnection to isolate the fault while minimizing the power outage area. To facilitate understanding of the technical solution of this invention, the specific implementation methods of this invention will be further explained and described below.

[0049] This invention classifies cross-sections according to the importance of constraints. If a system cannot operate normally or becomes highly unstable, or even collapses, due to a constraint, the cross-section determined by that constraint is considered more important. Based on this, the invention divides cross-sections into two levels and isolates them from high to low priority to prevent the scope of power outages from expanding.

[0050] In step S1, a first-level section is determined from the power grid according to the preset homogeneity constraint conditions.

[0051] The first step in disconnecting a generator set is to ensure synchronization constraints, meaning that the generators within each island must be synchronized. If the generators within an island are not synchronized, the generator set will immediately collapse due to loss of power angle synchronization after disconnection. Therefore, it is stipulated that under fault conditions, the sections selected based on synchronization constraints are the first-level sections, where synchronization constraints include the synchronization constraints of the generators and the asynchronous isolation constraints between the generator groups.

[0052] The coherence constraint of generators is used to ensure the synchronous operation of all generators within a single generator group and is the basis for grouping. The power angle is the essential characteristic of the synchronous operation state of generators; its changes directly reflect the tightness of rotor speed synchronization and electromagnetic connection, thus accurately defining the boundaries of coherent generator groups. Furthermore, the power angle responds most sensitively to grid disturbances, exhibiting synchronization characteristics within 1-3 seconds, earlier than indicators such as frequency and voltage. Therefore, coherence characteristics can be captured in advance, avoiding grouping lag errors.

[0053] Based on this, the present invention constructs constraints from the core electrical quantities of the power angle, specifically defining the first... A group of synchronized machines Any two generators in At all times after the disturbance occurs It must meet the following requirements:

[0054] ;

[0055] in, The preset error threshold is used; and They represent the first The generator and the first The power angle increment of the generator; This indicates the moment the fault occurred. This formula ensures that the power angle change trend of generators within the group is approximately consistent.

[0056] Inter-group power angle difference constraints can prevent confusion between different groups. These constraints need to clearly define the asynchronous characteristics between groups to ensure clear group boundaries and adapt to grid disconnection requirements. Specifically, for any two different groups... and Distinguishing them by a significant difference in work angle, thus, at all times after the disturbance occurs. It must meet the following requirements:

[0057] ;

[0058] in, This is the minimum power angle difference threshold between groups. This formula can ensure that different groups exhibit obvious asynchronous characteristics, and can be isolated by cross-sections during disconnection.

[0059] At the same time, if the system generator set is ,all Each coherent machine group must satisfy the condition of complete set coverage and non-overlapping, that is:

[0060] ;

[0061] To ensure that no clustering is omitted or repeated, the set of coherent clusters corresponding to any partitioning pattern is determined. Join the rest of the fleet satisfy:

[0062] ;

[0063] in, This represents the complete set of generators.

[0064] In step S2, based on the changes in electrical quantities before and after the fault, the comprehensive instability index of each potential section is calculated, and the sections are sorted from high to low according to the comprehensive instability index. Combined with the subsystem operation constraints, secondary sections that meet the conditions are selected from the sorted sections. For the selected primary and secondary sections, the line protection devices that are closest to their respective electrical distances are located according to priority.

[0065] While ensuring the normal operation of the system after grouping, it is also necessary to ensure the stability of the subsystem after disconnection. The cross-section should be selected first at the "weakest" or "most unstable" location. The initial selection of the cross-section can be based on whether the instability indicators such as the change in active power, voltage amplitude and phase angle, and frequency change rate before and after each fault exceed the set threshold. The weight of each indicator is calculated, and then the comprehensive instability index score of the cross-section is calculated.

[0066] 1) When a fault occurs, it can lead to changes in the transmission path or generator output, resulting in drastic changes in the cross-sectional power. Therefore, the change in active power is the most direct indicator reflecting the degree of power imbalance and instability. Specifically, an excessively large power difference indicates that the cross-section may have experienced a huge power surge, which is part of the instability path. The criterion can be expressed as:

[0067] ;

[0068] in, This indicates the active power flow at the cross section before the fault. This indicates the active power flow at the cross section after the fault. This indicates a threshold value set for changes in active power. This indicates the difference in active power at the cross section before and after the fault.

[0069] 2) Voltage instability often occurs alongside power angle instability, especially in receiving-end systems. A significant and sustained voltage drop after a fault is a key indicator of voltage stability problems; therefore, the criterion can be expressed as:

[0070] ;

[0071] in, and These represent the voltage amplitudes of the busbar on side A of section A before and after the fault, respectively. This represents the change in voltage amplitude before and after the fault on side A of section; similarly, and These represent the voltage amplitudes of the busbar on side B of section B before and after the fault, respectively. This indicates the change in voltage amplitude before and after the fault on side B of section B; It is a comprehensive indicator of the degree of voltage change across the entire cross-section, used to reflect the average degree of voltage deterioration across the entire cross-section. This indicates the threshold value set for voltage amplitude changes.

[0072] 3) The change in voltage phase angle difference is the most critical indicator for judging power angle stability. The essence of system instability is the separation of generator rotor angles, and the trend and speed of the phase angle difference change directly reflect the speed at which the two systems lose synchronization. Therefore, the criterion can be expressed as:

[0073] ;

[0074] in, , These represent the derivatives of the voltage phase angles on bus A and bus B with respect to time, respectively. Their physical meaning is the rate of change of the voltage phase angle on the corresponding bus side. The final phase angle difference rate of change is used to represent the instantaneous rate of change of the voltage phase angle difference on both sides of the cross section.

[0075] 4) The rate of frequency change is an important indicator for judging frequency stability and severe power imbalance. Specifically, regions with excessively high rate of frequency change indicate severe power imbalance and a lack of inertial support, representing potential breakpoints. Therefore, the criterion can be expressed as:

[0076] ;

[0077] in, and These represent the absolute values ​​of the rate of change of frequency on side A and side B, respectively. This represents the difference in the absolute value of the rate of change of frequency on both sides of the cross section. If this value is too large, it indicates that the frequencies on both sides of the cross section are accelerating their separation, which is a phenomenon that accompanies power angle instability, meaning that the two sides are no longer synchronized. This indicates the threshold value set for the rate of change of frequency.

[0078] In practical applications, to avoid reliance on a single indicator, a comprehensive criterion is used to improve reliability. Specifically, this invention employs a weighted comprehensive criterion, normalizing multiple indicators and then summing them in weights to obtain an Instability Severity Index (ISI). This index is calculated for all potential cross-sections and sorted in descending order of ISI, i.e.:

[0079] ;

[0080] in, , , , These represent the weighting coefficients of four instability indicators: the difference in active power at the cross section before and after the fault, the degree of voltage change at the cross section, the instantaneous rate of change of the voltage phase angle difference between the two sides of the cross section, and the difference in the absolute value of the frequency change rate between the two sides of the cross section, respectively, and satisfy the following conditions: The weight values ​​can be tuned through system simulation and practical experience (usually the weight of the phase difference). Highest).

[0081] Based on the instability comprehensive index score calculated above, the selection range of cross sections is gradually increased from high to low according to the instability score. If the selected set of cross sections, after being disconnected, meets the constraints of power balance, frequency and voltage balance, equipment operation limits, etc. of the subsystem, then it is set as a secondary cross section.

[0082] Furthermore, in the specific implementation process, the subsystem needs to comply with the following constraints:

[0083] 1) First, it is necessary to ensure that the subsystem can operate independently and stably after disconnection. That is, the total power generation capacity within the subsystem must be greater than or equal to the total load, and necessary reserve capacity must be reserved. Based on this, the first constraint condition can be expressed as:

[0084] ;

[0085] in, Representation Subsystem The sum of the maximum active power output capabilities of all the generators inside; Representation Subsystem The sum of the available active power output capacity of all internal new energy sources; Representation Subsystem The sum of the active power demands of all internal loads; Representation Subsystem Total active network loss.

[0086] 2) To ensure all equipment operates within its safe range, operational limits need to be defined, meaning the generator's active and reactive power outputs cannot exceed its rated range; and the power variation per unit time cannot exceed its ramp-up capability. Therefore, the generator's operational constraints can be expressed as:

[0087] ;

[0088] in, and They represent motors The lower and upper limits of active power, Indicates motor The active power; and They represent motors The lower and upper limits of reactive power. Indicates motor The reactive power.

[0089] 3) The constraints of distributed renewable energy (taking photovoltaics as an example) can be expressed as:

[0090] ;

[0091] in, Indicating distributed photovoltaic power in the power grid Constant effort This indicates the upper limit of photovoltaic power output.

[0092] 4) Frequency is an indicator of the active power balance of a subsystem. Each subsystem must maintain frequency stability under normal regulation conditions. Specifically, the steady-state frequency deviation constraint can be expressed as:

[0093] ;

[0094] in, Representation Subsystem The system frequency; and These represent the lower and upper limits of the system frequency, respectively, ensuring the normal operation of all generators and electrical equipment, especially frequency-based loads.

[0095] 5) Voltage is an indicator of the reactive power balance and network strength of a subsystem. Therefore, each node within the subsystem must satisfy the following condition:

[0096] ;

[0097] in, Represents a node The voltage amplitude; and These represent the lower and upper limits of the allowable voltage at that node, respectively.

[0098] In step S3, the phase voltage and line current of the line where the line protection device is located are monitored. If a sudden change in both phase voltage and line current is detected, a signal to release the blocking is generated.

[0099] To achieve rapid fault isolation, this invention adds a fault isolation blocking function to the existing line protection device, so as to quickly isolate the fault and ensure the stable operation of the power grid.

[0100] To accurately and quickly trigger the tripping and blocking mechanism, it is necessary to identify the commonalities in parameter changes across different fault types. For example, on the one hand, faults cause instantaneous voltage distortion (a sudden drop in voltage on the faulty phase during a short circuit, and a sudden rise in voltage on the non-faulty phases during a disconnection). Voltage mutations have the fastest response time, in the millisecond range, and can be directly acquired through voltage transformers without complex calculations, enabling immediate detection of system deviations from normal operating conditions. On the other hand, faults can cause drastic current changes (a sudden increase in current on the faulty line during a short circuit, and a sudden drop in current during a disconnection). Current transformers can capture current mutations in real time, and the magnitude of current changes is strongly correlated with the fault type and severity, allowing for rapid differentiation between minor disturbances and severe faults.

[0101] Meanwhile, considering that during a single-phase ground fault, the phase voltage of the faulty phase drops sharply while the phase voltage of the non-faulty phase may rise, this asymmetrical change in phase voltage can also serve as a key factor in identifying asymmetrical faults; however, line voltage cannot accurately distinguish between single-phase ground anomalies. Line current, collected by current transformers at both ends of the line, requires no additional calculations and can quickly acquire the current surge signal during a fault. Combined with changes in phase voltage, this allows for rapid identification of the fault type. Current power systems are predominantly three-phase three-wire systems, and the standard installation method for current transformers is to mount them on the outside of the phase lines, allowing direct acquisition of line current. Phase current requires the installation of current transformers inside each phase winding or at branch points, which not only limits space and complicates installation and maintenance but also significantly increases equipment costs and potential fault hazards. Therefore, this invention uses the sudden changes in phase voltage and line current as the conditions for releasing the blockade.

[0102] Because it is impossible to install the disconnection device at the selected section in a timely manner, the selection of a line protection device with a lockout cannot be arbitrary. This invention selects the line protection device with the smallest electrical distance from the optimal section, which can be defined as a "suboptimal section". That is, the optimality of the section is sacrificed, and the suboptimal section is selected for operation to ensure the speed of fault isolation.

[0103] Electrical distance is a crucial parameter in power grid disconnection studies, and current technologies mostly use line impedance as the electrical distance. When the electrical distance is small, the connection between the two nodes is relatively close; when the electrical distance is large, the connection between the two nodes is weak. Electrical distance can be expressed as:

[0104] ;

[0105] in, This represents the actual impedance of the line. This represents the actual resistance of the circuit. This represents the actual reactance of the line. The system reference impedance, The system reference voltage, This is the system's baseline capacity; This is the per-unit value for electrical distance.

[0106] In step S4, after the unlocking signal is issued, a delay timer is started. If the phase voltage and line current remain in an abnormal state during the delay time, the corresponding line protection device is controlled to perform a disconnection action.

[0107] Many disturbances in power systems are transient and can recover on their own without disconnecting components. If protection devices have no time delay, they may misjudge these transient disturbances as permanent faults and immediately trip the circuit breaker to disconnect lines or equipment. This can lead to unnecessary power outages, affecting not only user electricity consumption but also causing frequent grid connection or disconnection of distributed power sources, thereby compromising the stability of the power supply system. Therefore, this invention sets a time delay submodule based on the tripping interlocking device to distinguish between real faults and transient disturbances, while avoiding unnecessary power outages caused by tripping malfunctions.

[0108] In actual implementation, the logical flow of the action can be broken down into three core components: maintaining the lock, releasing the criterion, and delaying the action. Specifically:

[0109] During the interlocking phase, the protection function is initially in an interlocked state and does not respond to faults.

[0110] During the release criterion phase, the system status is monitored in real time. After selecting the primary and secondary sections, the line protection devices closest to the selected sections are located in the order of primary first and secondary second. If the line phase voltage and line current change abruptly, the signal to release the blocking is released directly.

[0111] After the lockout release signal is issued, a settable timer is started. If the phase voltage and line current are still at abnormal values ​​after the set time limit, the action is to disconnect the grid to maintain the stability of the power grid operation.

[0112] Through the above method, this invention, based on line protection devices and combined with a section priority-based disconnection method that considers the action sequence of sections, disconnects according to section priority, thus preventing problems such as an excessive number of subsystems, weak connections, and an expanded power outage area. Simultaneously, based on existing line protection devices, this invention adds a disconnection blocking design. After a fault, the line protection device closest to the optimal section is selected to release the disconnection blocking, isolating the fault. This solves the problem in existing technologies where frequent changes in grid oscillation sections due to the integration of new energy sources prevent timely and rapid disconnection based on online calculation results, achieving a balance between the optimality of section selection and the speed of fault isolation.

[0113] Example 2

[0114] This embodiment discloses an adaptive identification system for disconnection sections in a high-proportion renewable energy power grid.

[0115] An adaptive identification system for disconnection sections in high-proportion renewable energy power grids includes:

[0116] The primary section screening module is configured to determine primary sections from the power grid based on preset homogeneity constraints.

[0117] The secondary section screening module is configured to: calculate the instability comprehensive index of each potential section based on the changes in electrical quantities before and after the fault, sort the sections from high to low according to the instability comprehensive index, and select the secondary sections that meet the conditions from the sorted sections in combination with the subsystem operation constraints.

[0118] The priority order sorting module is configured to: for the selected primary section and secondary section, locate the line protection device that is closest to their respective electrical distance according to the priority order;

[0119] The release blocking control module is configured to: monitor the phase voltage and line current of the line where the line protection device is located; if a sudden change in both phase voltage and line current is detected, generate a release blocking signal.

[0120] The disconnection action execution module is configured to: start a delay timer after the release blocking signal is issued; if the phase voltage and line current remain in an abnormal state within the delay time, control the corresponding line protection device to perform the disconnection action.

[0121] Based on the above systematic design, in the specific implementation process, the cross-section selected according to the homogeneity constraint is used as the primary cross-section. The cross-section is initially selected by checking whether the instability indicators such as the change in active power, voltage amplitude and phase angle, and frequency change rate before and after each fault exceed the set threshold. The weight of each indicator is calculated, and the comprehensive instability index score of the cross-section is further calculated. The selection range of cross-sections is gradually increased from high to low according to the instability score. If the selected cross-section set meets the constraints such as power balance, frequency and voltage balance, and equipment operation limit of the subsystem after disconnection, it is set as a secondary cross-section.

[0122] After selecting the primary and secondary protection sections, the line protection device closest to the selected section is located in the order of primary to secondary. If the phase voltage and line current of the line change abruptly, a signal to release the blocking is released directly. After the signal to release the blocking is issued, a settable timer is started. If the phase voltage and line current are still at abnormal values ​​after the set time limit, the action is performed to disconnect the line to maintain the stability of the power grid. At the same time, a certain time interval is set to recalculate the protection section, so as to achieve online "approximate real-time" updating of the protection section.

[0123] Example 3

[0124] The purpose of this embodiment is to provide a computer-readable storage medium.

[0125] A computer-readable storage medium having a computer program stored thereon, which, when executed by a processor, implements the steps in the adaptive identification method for disconnection sections of a high-proportion renewable energy power grid as described in Embodiment 1 of this disclosure.

[0126] Example 4

[0127] The purpose of this embodiment is to provide an electronic device.

[0128] An electronic device includes a memory, a processor, and a program stored in the memory and executable on the processor. When the processor executes the program, it implements the steps in the adaptive identification method for disconnection sections of a high-proportion renewable energy power grid as described in Embodiment 1 of this disclosure.

[0129] The steps and methods involved in the apparatuses of Embodiments 2, 3, and 4 above correspond to those in Embodiment 1. For specific implementation details, please refer to the relevant description section of Embodiment 1. The term "computer-readable storage medium" should be understood as a single medium or multiple media including one or more instruction sets; it should also be understood as including any medium capable of storing, encoding, or carrying an instruction set for execution by a processor and enabling the processor to perform any of the methods in this invention.

[0130] Those skilled in the art will understand that the modules or steps of the present invention described above can be implemented using general-purpose computer devices. Optionally, they can be implemented using computer-executable program code, thereby allowing them to be stored in a storage device for execution by a computer device, or they can be fabricated as separate integrated circuit modules, or multiple modules or steps can be fabricated as a single integrated circuit module. The present invention is not limited to any particular combination of hardware and software.

[0131] While the specific embodiments of the present invention have been described above in conjunction with the accompanying drawings, this is not intended to limit the scope of protection of the present invention. Those skilled in the art should understand that various modifications or variations that can be made by those skilled in the art without creative effort based on the technical solutions of the present invention are still within the scope of protection of the present invention.

Claims

1. A method for adaptive identification of splitting section of high-proportion new energy power grid, characterized in that, include: Based on preset coherence constraints, a first-level section is determined from the power grid; wherein, the coherence constraints include coherence constraints of generators and asynchronous isolation constraints between generator groups; Based on the changes in electrical quantities before and after a fault, the comprehensive instability index of each potential cross section is calculated. The cross sections are then sorted from highest to lowest according to their comprehensive instability index. Combined with the subsystem's operational constraints, secondary cross sections that meet the subsystem's constraints are selected from the sorted cross sections. Specifically, the comprehensive instability index is calculated by weighting multiple electrical quantity change indicators, including changes in active power, voltage amplitude, voltage phase angle difference, and frequency change rate. Based on the calculated comprehensive instability index, the selection range of cross sections is gradually increased from highest to lowest based on their instability susceptibility score. If a selected set of cross sections, after being disconnected, meets the subsystem's constraints, it is designated as a secondary cross section. For the selected primary and secondary cross sections, locate the line protection devices that are closest to their respective electrical distances according to priority order; The phase voltage and line current of the line where the line protection device is located are monitored. If a sudden change in both phase voltage and line current is detected, a signal to release the blocking is generated. After the unlocking signal is issued, a delay timer is started. If the phase voltage and line current remain in an abnormal state within the delay time, the corresponding line protection device is controlled to perform a disconnection action.

2. The method of claim 1, wherein the method is characterized by, The operating constraints of the subsystem include: the subsystem's power generation capacity is not less than the sum of load demand and network loss; the voltage of each node in the subsystem is within a preset allowable range; the subsystem's frequency is within a preset allowable range; and the output of each power generation device is within the operating limit.

3. The method of claim 1, wherein the method is characterized by, The electrical distance is calculated based on the per-unit value of the line impedance.

4. The adaptive identification method for split-off sections in a high-proportion renewable energy power grid as described in claim 1, characterized in that, The criteria for determining when both phase voltage and line current change abruptly are: the instantaneous value of phase voltage exceeds the preset normal operating range, and the instantaneous value of line current exceeds the preset normal operating range.

5. The method of claim 1, wherein the method is characterized by, The delay time is used to distinguish between transient disturbances and permanent faults.

6. A split section adaptive identification system for a high proportion of new energy power grid, characterized in that, include: The primary section screening module is configured to: determine primary sections from the power grid according to preset coherence constraints; wherein, the coherence constraints include coherence constraints of generators and asynchronous isolation constraints between generator groups; The secondary section screening module is configured to: calculate the comprehensive instability index of each potential section based on the changes in electrical quantities before and after a fault, and sort the sections from high to low according to the comprehensive instability index. Then, combining this with the subsystem's operational constraints, it selects secondary sections from the sorted sections that meet the subsystem's constraints. Specifically, the comprehensive instability index is calculated by weighting multiple electrical quantity change indicators, including changes in active power, voltage amplitude, voltage phase angle difference, and frequency change rate. Based on the calculated comprehensive instability index, the selection range of sections is gradually increased from high to low according to their instability scores. If the selected section set, after being disconnected, meets the subsystem's constraints, it is designated as a secondary section. The priority order sorting module is configured to: for the selected primary section and secondary section, locate the line protection device that is closest to their respective electrical distance according to the priority order; The release blocking control module is configured to: monitor the phase voltage and line current of the line where the line protection device is located; if a sudden change in both phase voltage and line current is detected, generate a release blocking signal. The disconnection action execution module is configured to: start a delay timer after the release blocking signal is issued; if the phase voltage and line current remain in an abnormal state within the delay time, control the corresponding line protection device to perform the disconnection action.

7. A computer-readable storage medium having stored thereon a program, characterized in that, When the program is executed by the processor, it implements the steps in the adaptive identification method for disconnection sections of a high-proportion renewable energy power grid as described in any one of claims 1-5.

8. An electronic device comprising a memory, a processor, and a program stored in the memory and capable of running on the processor, characterized by When the processor executes the program, it implements the steps in the adaptive identification method for disconnection sections of a high-proportion renewable energy power grid as described in any one of claims 1-5.

Images